Headaches and your eyes

How a Headache Can Affect Your Eyes and Vision

By Troy Bedinghaus, OD Medically reviewed by Diana Apetauerova, MD on September 08, 2020

Have you ever had a headache that affected your vision? Sometimes a headache can cause pain around your eyes, even though the headache is not associated with a vision problem. On the other hand, a headache may be a sign that your eyes are changing and that it’s time to schedule an eye exam. Although headaches are rarely a medical emergency, a severe one should not be ignored or minimized.

headaches and vision — Verywell / Luyi Wang

Headaches That Affect Vision

Vision problems can sometimes be the consequence of a headache. This is especially true with migraines and cluster headaches.

Migraine Headache

A migraine headache can cause intense pain in and around your eyes. A migraine aura resembling flashing lights, a prismatic rainbow of lights or a zig-zag pattern of shimmering lights often precedes the actual headache. The aura typically lasts around 20 minutes.

Some people who experience a migraine aura never develop the actual headache, making the diagnosis of the visual disturbances difficult.¹ Migraines can also cause tingling or numbness of the skin. People with severe migraines may experience nausea, vomiting, and light sensitivity. Medications, certain foods, smells, loud noises, and bright lights can all trigger a migraine headache.An Overview of Migraine With Aura

Cluster Headache

Cluster headaches are severe headaches that occur in clusters and typically cause pain around the eyes. The pain often radiates down the neck to include the shoulder. Other symptoms include:

Tearing
Nasal drainage
Red eyes
Eyelid droop
Changes in pupil size

Cluster headaches may occur daily for several months at a time followed by a long period with no headaches. It is not known what causes cluster headaches, but they are clearly one of the most severe headaches one can experience.

Vision Problems That Cause Headaches

On the flip side, vision problems can cause headaches when you either overwork the eyes or struggle to maintain focus. By correcting the vision problem, you can often resolve the headache.

Eye Strain

Simply overusing the focusing muscles of your eyes can cause eye strain and headaches. This is an increasing problem in our high tech world

Small-screen texting and web browsing can easily cause eye strain, in part because the words and images on a computer screen are made up of pixels and do not have well-defined edges. The eyes cannot easily focus on pixels, so they must work harder even if an image is in high-resolution.² When the eye muscles become fatigued, a headache can develop around or behind the eyes.

Farsightedness

Adults and children with uncorrected farsightedness (hypermetropia) will often experience a frontal headache (also known as a “brow ache”). If you are farsighted, you may find it difficult to focus on nearby objects, resulting in eye strain and headaches. As you subconsciously compensate for your farsightedness by focusing harder, the headaches can become worse and more frequent.

Presbyopia

Around the age of 40, people begin to find it difficult to focus on nearby objects. Near point activities, such as reading or threading a needle, are often difficult to perform because of blurring. This is an unavoidable condition known as presbyopia that affects everyone at some point. Headaches develop as you try to compensate for the lack of focusing power. Reading glasses can often relieve the underlying eye strain.

Occupations requiring close-up work, exposure to sunlight for longer periods of time, and farsightedness were the most common risk factors for presbyopia.³Presbyopia: Close-Up Vision Loss and What to Do About It

Giant Cell Arteritis

Also known as temporal arteritis, giant cell arteritis (GCA) is an inflammation of the lining of the arteries that run along the temple. GCA usually creates a headache that causes constant, throbbing pain in the temples. Vision symptoms occur as a result of a loss of blood supply to the optic nerve and retina. Other symptoms include:

Fever, fatigue and muscle aches
Scalp tenderness
Pain while chewing
Decreased vision

GCA is considered a medical emergency. If left untreated, the condition may cause vision loss in one or both eyes. A delayed diagnosis is the most common cause of GCA-associated vision loss.⁴2:18

What Is a Retinal Migraine?

Acute Angle-Closure Glaucoma

Acute angle-closure glaucoma (AACG) is a rare type of glaucoma that causes a sudden onset of symptoms, including headaches. Eye pressure rises quickly in AACG causing increased eye redness, eye pain, and cloudy vision. A mid-dilated pupil (in which pupil dilation is sluggish and incomplete) is one of the most important diagnostic features of AACG.⁵

Ocular Ischemic Syndrome

Ocular ischemic syndrome (OIS) is a condition that develops due to a chronic lack of blood flow to the eye. This condition often causes a headache, decreased vision, and a host of other signs, including cataracts, glaucoma, iris neovascularization (the development of new weak blood vessels in the iris), and retinal hemorrhage. White spots on the retina indicate a lack of blood flow and oxygen to the retinal tissue.2:18

What Is a Retinal Migraine?

Herpes Zoster

Also known as shingles, herpes zoster is known for causing headaches, vision changes and severe pain around the head and eye. Herpes zoster is a reactivation of the chickenpox virus and affects a single side of the body. A headache usually precedes an outbreak of painful skin blisters.

Herpes zoster around the eyes is serious and requires immediate medical attention (including antiviral medication) to prevent damage to the ocular nerves and eyes. Complications include corneal clouding, glaucoma, and optic nerve atrophy (deterioration).⁶

Pseudotumor Cerebri

Pseudotumor cerebri is a condition that occurs when the pressure within the skull increases for no apparent reason. For this reason, pseudotumor cerebri is also referred to as Idiopathic Intracranial hypertension (“idiopathic” meaning of unknown origin and “hypertension” meaning high blood pressure).

Pseudotumor cerebri often causes a headache and changes in vision. If left untreated, pseudotumor cerebri can lead to vision loss as the pressure places strain on the optic nerves. Fortunately, while 65% to 85% of people with pseudotumor cerebri will experience visual impairment, the condition is usually transient and will normalize when the hypertension is controlled.

February 15, 2021

Foods that lower blood sugar

When a person has diabetes, either their body does not produce enough insulin, or it cannot use the insulin correctly, so glucose accumulates in the blood. High levels of blood glucose can cause a range of symptoms, from exhaustion to heart disease.

One way to control blood sugar is to eat a healthful diet. Generally, foods and drinks that the body absorbs slowly are best because they do not cause spikes and dips in blood sugar.

The glycemic index (GI) measures the effects of specific foods on blood sugar levels. People looking to control their levels should pick foods with low or medium GI scores.

A person can also pair foods with low and high GI scores to ensure that a meal is balanced.

Below are some of the best foods for people looking to maintain healthy blood sugar levels.

1. Whole wheat or pumpernickel bread

Many kinds of bread are high in carbohydrates and quickly raise blood sugar levels. As a result many breads should be avoided.

However, pumpernickel bread and 100 percent stone-ground whole wheat bread have low GI scores, at 55 or less on the GI scale.

Pumpernickel and stone-ground whole wheat breads have lower GI scores than regular whole wheat bread because the ingredients go through less processing.

Processing removes the fibrous outer shells of grains and cereals. Fiber slows digestion and helps to stabilize blood sugar levels.

In a 2014 study, researchers reported that spelt and rye both caused low initial glycemic responses in rats. They also found that these ancient wheat types, as well as emmer and einkorn, suppressed genes that promote glucose metabolism

2. Most fruits

Except for pineapples and melons, most fruits have low GI scores of 55 or less.

This is because most fruits contain lots of water and fiber to balance out their naturally occurring sugar, which is called fructose.

However, as fruits ripen, their GI scores increase. Fruit juices also have very high GI scores because juicing removes the fibrous skins and seeds.

A large 2013 study found that people who consumed whole fruits, especially blueberries, grapes, and apples, had significantly lower risks of developing type 2 diabetes.

The researchers also reported that drinking fruit juice increased the risk of developing the condition.

3. Sweet potatoes and yams

Regular potatoes have a high GI score, but sweet potatoes and yams have low scores and are very nutritious.

Some research indicates that the flesh of the sweet potato contains more fiber than the skin, indicating that the whole vegetable could be beneficial for those with diabetes.

Reporting the findings of an animal study, the researchers also noted that sweet potato consumption may lower some markers of diabetes.

While there is still no conclusive evidence that sweet potatoes can help to stabilize or lower blood sugar levels in humans, they are undoubtedly a healthful, nutritious food with a low GI score.

People can substitute sweet potatoes or yams for potatoes in a variety of dishes, from fries to casseroles.

4. Oatmeal and oat bran

Oatmeal in a bowl — Oats contain B-glucans, which help maintain glycemic control.

Oats have a GI score of 55 or lower, making them less likely to cause spikes and dips in blood sugar levels.

Oats also contain B-glucans, which can do the following:

reduce glucose and insulin responses after meals
improve insulin sensitivity
help maintain glycemic control
reduce blood lipids (fats)

A 2015 review of 16 studies concluded that oats have a beneficial effect on glucose control and lipid profiles in people with type 2 diabetes. Determining the impact of oat consumption on type 1 diabetes requires more research.

Doctors still recommend that people with diabetes limit their consumption of oatmeal because 1 cup contains roughly 28 grams of carbohydrates.

5. Most nuts

Nuts are very rich in dietary fiber and have GI scores of 55 or less.

Nuts also contain high levels of plant proteins, unsaturated fatty acids, and other nutrients, including:

antioxidant vitamins
phytochemicals, such as flavonoids
minerals, including magnesium and potassium

A 2014 systemic review concluded that eating nuts could benefit people with diabetes.

As with other foods in this article, it is best to eat nuts that are as whole and unprocessed as possible. Nuts with coatings or flavorings have higher GI scores than plain nuts.

6. Legumes

Legumes, such as beans, peas, chickpeas, and lentils, have very low GI scores.

They are also a good source of nutrients that can help maintain healthy blood sugar levels. These nutrients include:

fiber
complex carbohydrates
protein

A 2012 study found that incorporating legumes into the diet improved glycemic control and lowered the risk of coronary heart disease in people with type 2 diabetes.

Avoid legume products that contain added sugars and simple starches, such as those in syrups, sauces, or marinades. These additions can significantly increase a product’s GI score.

7. Garlic

Garlic is a popular ingredient in traditional medicines for diabetes and a wide variety of other conditions.

The compounds in garlic may help reduce blood sugar by improving insulin sensitivity and secretion.

In a 2013 study, 60 people with type 2 diabetes and obesity took either metformin alone or a combination of metformin and garlic twice daily after meals for 12 weeks. People who took metformin and garlic saw a more significant reduction in their fasting and post-meal blood sugar levels.

People can eat garlic raw, add it to salads, or use it in cooked meals.

8. Cold-water fish

fish on a plate — Cod does not contain carbohydrates and may reduce the risk of developing type 2 diabetes.

Fish and other meats do not have GI scores because they do not contain carbohydrates.

However, cold-water fish may help manage or prevent diabetes better than other types of meat.

A 2014 study included data taken from 33,704 Norwegian women over a 5-year period. The researchers found that eating 75–100 grams of cod, saithe, haddock, or pollock daily reduced the risk of developing type 2 diabetes.

However, the researchers were uncertain whether the reduction in risk was a direct result of eating the fish or whether other healthful lifestyle factors, such as exercise, could have influenced the findings.

9. Yogurt

Eating plain yogurt daily may reduce the risk of type 2 diabetes.

Authors of a large 2014 meta-analysis concluded that yogurt may be the only dairy product that lowers the risk of developing the condition. They also noted that other dairy products do not seem to increase a person’s risk.

Researchers are still unsure why yogurt helps lower the risk of type 2 diabetes.

However, plain yogurt is generally a low-GI food. Most unsweetened yogurts have a GI score of 50 or less.

It is best to avoid sweetened or flavored yogurts, which often contain too much sugar for a person looking to lower their blood sugar levels. Greek-style yogurt can be a healthful alternative.

Other ways to lower blood sugar levels

Eating a healthful, well-balanced diet is key. Additional strategies to help lower or manage blood sugar levels include:

staying hydrated by drinking plenty of clear liquids
exercising regularly
eating small portions more frequently
not skipping meals
managing or reducing stress
maintaining a healthy body weight or losing weight, if necessary

People with diabetes may also need to take medications and measure their blood sugar regularly to reduce the risk of potentially dangerous symptoms and complications.

Speak with a doctor about how to incorporate a healthful diet into a diabetes care plan.

February 4, 2021

Eye Diseases in Africa

Blindness is a major public health problem in African because of the sheer number of people so afflicted. Economic survival is a struggle for the average, non-handicapped person in a developing country. The burden of blindness is therefore a major added frustration to the individual’s economic independence and social development.

Eye care delivery has not received much attention in many African countries. Although the need for eye care cannot be denied, it is competing for scarce resources with more compelling problems like high maternal and infant mortality and acute medical and surgical problems.c Ophthalmologists are few and tality and acute medical and surgical problems. Ophthamologists are few and the traditional hospital-based curative ophthalmic practice is expensive to run.

By and large, ophthalmologists, optometrists and hospitals are situated in big cities and towns while more than 80% of the population lives in rural areas and villages.The majority of the population is therefore underserved or not served at all. For every patient who attends the hospital, there are probably 4-5 needy patients who have not visited the doctor because they are too poor, too far from the hospital or just ignorant of what can be done. Besides, taboos and sociocultural attitudes often discourage patients from using existing modern facilities. Consequently, diseases are usually seen at an advanced stage. These factors, contributing to late presentation, together with inadequate facilities lead to a pool of curably blind as is seen in the cataract backlog in Africa.

The eye diseases seen in Africa are often no different from those encountered in Europe; most of them are treatable or preventable, but their neglect has a devastating effect on vision.

Cataracts are very commonly seen in Africa, accounting for approximately 50% of all cases of blindness. They may be congenital in origin; often due to intrauterine infection like rubella, or metabolic diseases in the child like galactosaemia. Cataracts may also complicate injuries to the eye; but more commonly they are seen in the elderly.

Senile cataracts are known to occur at an earlier age in the tropics, and recent work suggests that severe diarrheoal diseases early in life may be a contributory factor. It will be interesting to see in a few year’s time the effect of oral rehydration therapy on the prevalence of cataracts. The surgical treatment of cataracts is very rewarding, but advantage of this fact is often not taken, due mainly to inadequate facilities and ignorance. Mobile eye units being operated by various non-governmental organizations are now unable to afford the cost of corrective glasses, as is often the case, the improvement in vision is often adequate to enable him to look after himself and move around, thereby ceasing to be a burden on family and friends. Although more cataract operations are now being done, contact lenses and intraocular lens implantations, which have become routine in developed countries, are not usually available in Africa.

Infections of the external eye are very common, notably among which are trachoma, conjuctivitis of the newborn, epidemic haemorrhagic keratocon-junctivitis, corneal ulcers, measles, Keratoconjunctivitis and leprosy. The infection may spread to the inner eye and lead to loss of the eyre. Eye infections may be responsible for up to 25% of all cases of blindness in Africa.

February 2, 2021

Ocular Trauma

^{Eye Injuries}

Eye Trauma

Eye trauma refers to damage caused by a direct blow to the eye. The trauma may affect not only the eye, but the surrounding area, including adjacent tissue and bone structure.

There are many different forms of trauma, varying in severity from minor injury to medical emergencies. Even in cases where trauma seems minor, every eye injury should be given medical attention.

What Causes Eye Trauma?

When the eye is hit with blunt force, it suddenly compresses and retracts. This can cause blood to collect underneath the hit area, which leads to many of the common symptoms of eye trauma.

Symptoms of Eye Trauma

Symptoms of eye trauma may include:

Pain
Trouble seeing
Cuts to the eyelid
One eye not moving as well
One eye sticks out
Blood in the clear part of the eye
Unusual pupil size or shape
Something embedded in the eye
Something under the eyelid that cannot be easily removed

Treatments for Eye Trauma

Every eye injury should be given medical attention; do not touch, rub or try to remove any object in the eye. If the eye has been cut or there is an object in the eye, rest a protective shield – such as a paper cup – on the bone around your eye. Make sure there is no pressure on the eye itself. Seek immediate, professional medical attention.

In minor cases of trauma, such as a black eye from a sports injury, applying cold to the affected area can help bring swelling down, and allow the affected area to heal faster. However, even in cases where trauma seems minor, every eye injury should be given medical attention.

The best way to avoid eye trauma is to prevent it by using protective eyewear while doing things that may put them at risk. Activities include home repair, yard work, cleaning, cooking, and playing sports. In most cases of injury, people report not properly protecting their eyes – which shows that proper precautions may prevent an eye injury.

January 31, 2021

Light and your eyes

Explore the latest research regarding bright lights and retina damage, and how to properly protect your eyes.

Parents will often tell children not to stare at the sun. This is good advice, since permanent retinal damage occurs after staring for just a few minutes! This is called solar retinopathy. Lasers and very bright industrial lights can also damage the retina.

Since very bright lights can damage the retina in a short period of time, can long-term exposure to moderately bright light cause retinal damage? The answer is maybe, and why not protect yourself against this possibility?

Research Findings on Bright Lights and Eye Damage

In the Chesapeake Bay Waterman Study, which analyzed fisherman exposed to bright light reflected off the water every day, blue light exposure was found to increase the risk of age-related macular degeneration (AMD). This conclusion, while suggestive, as not definitive, since it is difficult to quantify light exposure in everyday life.

In experimental mice, bright light does cause permanent retinal damage. If the light has the intensity of sunlight, short exposure times can cause damage. If the light is not quite so bright, chronic exposure over days to weeks can cause permanent damage. This is thought to be due to what is called photo-oxidative damage; the light reacts with the retina to produce molecules that are very reactive and cause damage to surrounding molecules.

If light exposure is a risk factor for AMD, then it would be expected that people with lighter colored eyes, which let in more light, would have a higher risk. Indeed, African-Americans have a much lower risk of AMD than Caucasians. Some studies have suggested that people with blue eyes have the highest risk.

Some experimental mice and even a particular breed of dog have genetic mutations that make their retinas extremely sensitive to light; permanent retinal damage can be caused by light levels that would not harm animals with normal retinas. Analogously, people with AMD, Stargardt disease, or retinitis pigmentosa may be more susceptible to retinal light damage than people with normal retinas.

How Can I Protect My Eyes from Bright Lights?

The simplest way to protect against possible retinal light damage is to wear sunglasses and a hat. The sunglasses should have dark tint. If you hold the glasses up to a light, the light coming through the lenses should appear grey, brown, or yellowish brown—not blue, which is probably the most damaging light wavelength. If picking ready-made sunglasses in a store, choose the ones that transmit the least light (but only wear them if you can still see well enough). If ordering custom sunglasses, ask the optician for a very dark tint. Polarization will also decrease the amount of light coming through sunglasses and helps reduce glare. UV protection helps protect the lens inside the eye against cataracts. Since UV light is blocked by the lens inside the eye it is the visible light that can harm the retina.

Since it is thought that blue light can damage the retina, ophthalmologists can now offer blue-blocking lens implants when performing cataract surgery. While these may be helpful, the same effect can be achieved by wearing sunglasses.

Are Indoor Lights Damaging to the Eyes?

Could indoor lights be harmful? It is prudent to use the amount of light you need to read or perform activities of daily life, but there is no reason to exceed this amount with very bright lighting. When choosing light bulbs, those with the “warm” color spectrum, favoring reds and greens over the “cool” blues, are typically more comfortable for reading and may be safer. Energy-efficient LED bulbs come in warm or full spectrum varieties. As with most things in life, light is good, in moderation

–

Joshua Dunaief, MD, PhDScheie Eye Institute, University of Pennsylvania

January 20, 2021

Transposition of ophthalmic lenses

Transposition

by Andrew Othuke Akpeli

Introduction / definition

According to Efe (2012) transposition as the process of changing a lens prescription from one form to another equivalent form without changing the value i.e. it is also to rewrite the expression of its power without actually changing its value. It can also be define as the act of converting the prescription of an ophthalmic lens form a sphere with minus cylinder form to a sphere with plus cylinder form or vice vise. Example – 3D sphere – 2D cylinder axis 180 transpose to – 5D sphere + 2D cylinder axis 90 prescription consists of the sphere, cylinder and the axis. The sphere correct hyperopic and myopia, the cylinder corrects the amount of astigmatism and the axis shows where the stigmatism correction is located.

Types of transposition

Flat Transposition

Toric transposition

Flat transposition: This is the process of transposition whereby the cylinder power and spherical power is separated by 90. The flat transposition is use in the dispensing laboratory.

Toric transposition: This is the process of transposition whereby the cylinder power and spherical power is not separated by 90. The toric transposition is use in the production laboratory.

Lens prescription

Lens prescription can be written in any of this form

Plano cylinder
Sphero cylinder
Cross cylinder

Plano cylinder: This has one surface plane and the other, either + or – cylinder eg (plano x 0.50DCx180)

Sphere cylinder: This has one surface spherical and the other cylindrical eg +0.75DS -1.00DC x 50

Cross cylinder: This has one surface a cylinder and other another cylinder eg +1.50DCx180/0.75DCx90

Rules of transposition

Transposition of sphero-cylindrical prescription from plus to minus cylinder (or vice versa)

Rules

Step 1: New spherical power: add the power of the sphere to the power of cylinder (algebraically) of a given prescription

Step 2: New cylindrical power: change the sign of the cylinder (plus or minus to the opposite sign) with same power.

Step 3: New axis: add or subtract 90 from the given axis (depending on which value is higher) i.e. if is below 90, add 90 to it but if is above 90 subtract 90. Let us now apply this rule to a specific sphero – cylindrical prescription.

Given + 1.00DS – 1.00DC x 90

From the on set, it is important to note that this prescription has been written in minus cylinder from. To convert it to plus cylinder form, we apply the rules as follows.

Rule 1: (new spherical power); (+1.00) + (1.00) = plano

Rule 2: (new cylindrical power) change the cylinder sign with same value = +1.00DC

Rule 3: (new axis) add or subtract 90 (depending on which value is greater) i.e if is below 90, add 90 to it but if it is above 90 subtract 90. 90 + 90 = 180. Therefore, the transposed plus cylindrical form of a given prescription is plano + 1.00DC x 180

Given -2.00DS + 1.50DC x 45

To transpose this prescription from plus to its minus cylindrical form we apply same rules as follows:

Rule 1: (new sphere power) – 2.00 + 1.50 = – 0.50DS

Rule 2: (new cylinder power) change the cylinder sight with the same power -1.50DC

Rules 3: (New axis) i.e if is below 90, add 90 to it but if is above 90 subtract 90 45 + 90 = 135

Thus, the transpose form of this prescription into its minus cylindrical form is equivalent to :- 0.50DS – 135

Transposition of sphero-cylinders into cross cylinders

A sphero-Cylindrical prescription can be broken down into two cross-cylinder that it was originally made of this form of. This form of transposition is also guided by its set of rules

Rules

Rule 1. (1^st Cross-Cylinder): Take the spherical power of a given sphero-cylinder prescription and write this as a cross cylinder with its axis 90 away from the axis of a given sphero-cylindrical prescription.

Rule 2. (2^nd cross-cylinder) add the spherical and cylindrical power of a given sphero-cylindrical prescription and write this as cross cylinder with its axis same as the axis of the sphero-cylindrical prescription.

Rules 3. (both cross-cylinder) combine the two cross cylinder obtain from rule 1 and rule 2 above as the equivalent cross cylinder for the sphero-cylindrical prescription.

The follow are some examples to illustrate the application of the rules

Given -4.00DS – 0.50DC x 90

Rule 1. (1^st cross-cylinder) -4.00DC x 180

Rule 2. (2^nd cross-cylinder) -4.50DC x 90

Rule 3. (3^rd cross-cylinder) +4.00DC x 180/-4.50DC x 90

Given: -1.50DS + 0.75DC x 45

Rule 1. (1^st cross-cylinder) -1.00DC x 135

Rule 2. (2^nd cross-cylinder) -0.75DC x 45

Rule 3. (3^rd cross-cylinder) +1.50DC x 135/-075DC x 45

Transposition of 2 cross-cylinder into sphero cylinder

Rule 1: (sphere power) take either power of the 2 cross-cylinders as spherical power of the new sphero-cylinders as spherical power of the new sphero-cylinderical prescription.

Rule 2: (cylindrical power) subtract the power of the cylindrical chosen as sphere from the power of the second cross-cylinder and make this the cylinder of the new sphero-cylinder

Rule 3: (axis) take the axis of the cross-cylinder that was not chosen as sphere power as axis of the new sphero-cylinderical prescription

The following are some examples to illustrate application of the rule

Given: +2.00DS x 180/+1.00DC x 90

Rule 1. (sphere power) + 2.00DS

Rule 2. (cylindrical power) +1.00 – (+2.00) = -1.00DC

Rule 3. (axis): 90

Therefore, the sphero-cylindrical prescription is: +2.00DC – 1.00DC x 90

Given: -1.00DC x 135/-3.00DCx45

Rule 1. (sphere power) -3.00DS

Rule 2. (cylindrical power) -1.00 – (-3.00)

-1.00 + 3.00 = +2.00

Rule 3. (axis): 135

Therefore. The sphero-cylindrical prescription is: -3.00DC + 2.00DC x 135

Toric transposition

A toric lens is practical same as a cylindrical lens. By these design the surfaces of toric lenses are more curved (or bent) than the surfaces of cylindrical lenses. But unlike the flat cylindrical lens prescription, the toxic prescription will indicate the various curves that have been incorporated during the process of production to arrive at a particular prescription. This explain why a toric lens prescription have the following three parts

The base curve (BC)
The cross curve (CC)
The sphere curve (SC)

To produce a particular prescription from a lens blanks these three components with their different powers will be generated in the factory. This process is called surfacing

Since most of the physical properties of toric lenses are similar to cylindrical lens and vice versa. This means that given a specific toric lens prescription, the sphero-cylindrical prescription of equivalent power can be deduced from it by applying the following rules.Related Topic procreteconstruction 3 people Job Vacancy in Australia

Rule 1 (sphere power) = base curve + sphere curve

Rule 2 (cylinder power) = cross curve – base curve

Rule 3 (axis) same as axis of cross curve

The following example is meant to illustrate the application of those rules:

Rule 1 (sphere power): +2.00 + (-3.00) = -1.00DS

Rule 2 (cylinder power) +4.00 – 2.00 = +2.00DC

Rules 3 (axis) = 180

Sphero-cylindrical prescription: -1.00DS + 2.00DC x 180

Importance of transposition

After an optometrist has done a refraction for a patient, the optometrist takes the prescription to the optician and the lens prescription is given to be + 1.00DS-2.00DC x 180 and the optician check the stocks of lens available and founds that (+1.00DS – 2.00DC x 180) prescription is not in stock, what the optician need to do is to transpose the prescription.

+1.00DS – 2.00DC x 180

– 1.00DS + 2.00DC x 90.

So instead of the optician finding it as a problem of getting + 1.00DS-2.00DC x 180 the optician simply go for -1.00DS + 2.00DC x90 it makes dispensing cylindrical lenses easy instead of keeping your patient waiting or ordering for more lenses when unknowing to you it is your stock.

Conclusion

In conclusion, transposition is important because it helps and optician to get an equivalent (same) prescription for a given prescription. It is also important for an optician to be acquitted with the knowledge of transposition. An optician should not be ignorant of keeping a patient waiting or placing an order for a cylindrical lens prescription when there is an alternative form of that prescription in stock, all you need to do is to transpose.

References

Efe Odjimogho, O.D. FNCO (2012). In laboratory manual, senior lecturer optometry department faulty of life science, university of Benin.

Mr. Nsubuisi Igboekwe (2013). Ophthalmic workshop dispensing lab ii

San Francisco, American Academy of ophthalmology 2011-2012

Allied Health on the job training kit 2011

Dallas American Health Association Academy of ophthalmology 2011 (Revised as appropriate)Facebook Twitter Email WhatsApp Pinterest

December 10, 2020

What Is Type 2 Diabetes?

Type 2 Diabetes

What Is Type 2 Diabetes?

Type 2 diabetes is a lifelong disease that keeps your body from using insulin the way it should. People with type 2 diabetes are said to have insulin resistance.

People who are middle-aged or older are most likely to get this kind of diabetes. It used to be called adult-onset diabetes. But type 2 diabetes also affects kids and teens, mainly because of childhood obesity.

Type 2 is the most common type of diabetes. There are about 29 million people in the U.S. with type 2. Another 84 million have prediabetes, meaning their blood sugar (or blood glucose) is high but not high enough to be diabetes yet.

Signs and Symptoms of Type 2 Diabetes

The symptoms of type 2 diabetes can be so mild that you don’t notice them. About 8 million people who have it don’t know it. Symptoms include:

Being very thirsty
Peeing a lot
Blurry vision
Being cranky
Tingling or numbness in your hands or feet
Fatigue/feeling worn out
Wounds that don’t heal
Yeast infections that keep coming back
Feeling hungry
Weight loss without trying
Getting more infections

If you have dark rashes around your neck or armpits, see your doctor. These are called acanthosis nigricans, and they can be signs that your body is becoming resistant to insulin.CONTINUE READING BELOW

Causes of Type 2 Diabetes

Your pancreas makes a hormone called insulin. It helps your cells turn glucose, a type of sugar, from the food you eat into energy. People with type 2 diabetes make insulin, but their cells don’t use it as well as they should.

At first, your pancreas makes more insulin to try to get glucose into your cells. But eventually, it can’t keep up, and the glucose builds up in your blood instead.

Usually, a combination of things causes type 2 diabetes. They might include:

Genes. Scientists have found different bits of DNA that affect how your body makes insulin.
Extra weight. Being overweight or obese can cause insulin resistance, especially if you carry your extra pounds around your middle.
Metabolic syndrome. People with insulin resistance often have a group of conditions including high blood sugar, extra fat around the waist, high blood pressure, and high cholesterol and triglycerides.
Too much glucose from your liver. When your blood sugar is low, your liver makes and sends out glucose. After you eat, your blood sugar goes up, and your liver will usually slow down and store its glucose for later. But some people’s livers don’t. They keep cranking out sugar.
Bad communication between cells. Sometimes, cells send the wrong signals or don’t pick up messages correctly. When these problems affect how your cells make and use insulin or glucose, a chain reaction can lead to diabetes.
Broken beta cells. If the cells that make insulin send out the wrong amount of insulin at the wrong time, your blood sugar gets thrown off. High blood sugar can damage these cells, too.

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Type 2 Diabetes Risk Factors

Certain things make it more likely that you’ll get type 2 diabetes. The more of these that apply to you, the higher your chances of getting it are. Some things are related to who you are:

Age. 45 or older
Family. A parent, sister, or brother with diabetes
Ethnicity. African American, Alaska Native, Native American, Asian American, Hispanic or Latino, or Pacific Islander American

Risk factors related to your health and medical history include:

Prediabetes
Heart and blood vessel disease
High blood pressure, even if it’s treated and under control
Low HDL (“good”) cholesterol
High triglycerides
Being overweight or obese
Having a baby who weighed more than 9 pounds
Gestational diabetes while you were pregnant
Polycystic ovary syndrome (PCOS)
Depression

Other things that raise your risk of diabetes have to do with your daily habits and lifestyle. These are the ones you can do something about:

Getting little or no exercise
Smoking
Stress
Sleeping too little or too much

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Type 2 Diabetes Diagnosis and Tests

Your doctor can test your blood for signs of type 2 diabetes. Usually, they’ll test you on 2 days to confirm the diagnosis. But if your blood glucose is very high or you have many symptoms, one test may be all you need.

A1c. It’s like an average of your blood glucose over the past 2 or 3 months.
Fasting plasma glucose. This is also known as a fasting blood sugar test. It measures your blood sugar on an empty stomach. You won’t be able to eat or drink anything except water for 8 hours before the test.
Oral glucose tolerance test (OGTT). This checks your blood glucose before and 2 hours after you drink something sweet to see how your body handles the sugar.

Type 2 Diabetes Treatment

Managing type 2 diabetes includes a mix of lifestyle changes and medication.

Lifestyle changes

You may be able to reach your target blood sugar levels with diet and exercise alone.

Weight loss. Dropping extra pounds can help. While losing 5% of your body weight is good, losing at least 7% and keeping it off seems to be ideal. That means someone who weighs 180 pounds can change their blood sugar levels by losing around 13 pounds. Weight loss can seem overwhelming, but portion control and eating healthy foods are a good place to start.
Healthy eating. There’s no specific diet for type 2 diabetes. A registered dietitian can teach you about carbs and help you make a meal plan you can stick with. Focus on:

Eating fewer calories
Cutting back on refined carbs, especially sweets
Adding veggies and fruits to your diet
Getting more fiber

Exercise. Try to get 30 to 60 minutes of physical activity every day. You can walk, bike, swim, or do anything else that gets your heart rate up. Pair that with strength training, like yoga or weightlifting. If you take a medication that lowers your blood sugar, you might need a snack before a workout.
Watch your blood sugar levels. Depending on your treatment, especially if you’re on insulin, your doctor will tell you if you need to test your blood sugar levels and how often to do it.

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Medication

If lifestyle changes don’t get you to your target blood sugar levels, you may need medication. Some of the most common for type 2 diabetes include:

Metformin (Fortamet, Glucophage, Glumetza, Riomet). This is usually the first medication used to treat type 2 diabetes. It lowers the amount of glucose your liver makes and helps your body respond better to the insulin it does make.
Sulfonylureas. This group of drugs helps your body make more insulin. They include glimepiride (Amaryl), glipizide (Glucotrol, Metaglip), and glyburide (DiaBeta, Micronase).
Meglitinides. They help your body make more insulin, and they work faster than sulfonylureas. You might take nateglinide (Starlix) or repaglinide (Prandin).
Thiazolidinediones. Like metformin, they make you more sensitive to insulin. You could get pioglitazone (Actos) or rosiglitazone (Avandia). But they also raise your risk of heart problems, so they aren’t usually a first choice for treatment.
DPP-4 inhibitors. These medications — linagliptin (Tradjenta), saxagliptin (Onglyza), and sitagliptin (Januvia) — help lower your blood sugar levels, but they can also cause joint pain and could inflame your pancreas.
GLP-1 receptor agonists. You take these medications with a needle to slow digestion and lower blood sugar levels. Some of the most common ones are exenatide (Byetta, Bydureon), liraglutide (Victoza), and semaglutide (Ozempic).
SGLT2 inhibitors. These help your kidneys filter out more glucose. You might get canagliflozin (Invokana), dapagliflozin (Farxiga), or empagliflozin (Jardiance).
Insulin. You might take long-lasting shots at night, such as insulin detemir (Levemir) or insulin glargine (Lantus).

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Even if you change your lifestyle and take your medicine as directed, your blood sugar may still get worse over time. That doesn’t mean you’ve done something wrong. Diabetes is progressive, and many people eventually need more than one drug.

When you take more than one drug to control your type 2 diabetes, that’s called combination therapy.

You and your doctor should work together to find the best mix for you. Usually, you’ll keep taking metformin and add something else.

What that is may depend on your situation. Some drugs control blood sugar spikes (your doctor may call this hyperglycemia) that come right after meals, for instance. Others are more effective at stopping drops in blood sugar (hypoglycemia) between meals. Some may help with weight loss or cholesterol, as well as your diabetes.

You and your doctor should talk about any possible side effects. Cost may be an issue as well.

If you take medication for something else, that will need to be factored into any decision.CONTINUE READING BELOW

You’ll need to see your doctor more often when you start taking a new combination of drugs.

You might find that adding a second drug doesn’t bring your blood sugar under control. Or the combination of two drugs might work only for a short time. If that happens, your doctor might consider a third noninsulin drug, or you may start insulin therapy.

Type 2 Diabetes Prevention

Adopting a healthy lifestyle can help you lower your risk of diabetes.

Lose weight. Dropping just 7% to 10% of your weight can cut your risk of type 2 diabetes in half.
Get active. Thirty minutes of brisk walking a day will cut your risk by almost a third.
Eat right. Avoid highly processed carbs, sugary drinks, and trans and saturated fats. Limit red and processed meats.
Quit smoking. Work with your doctor to keep from gaining weight after you quit, so you don’t create one problem by solving another.

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Type 2 Diabetes Complications

Over time, high blood sugar can damage and cause problems with your:

Heart and blood vessels. You’re up to five times more likely to get heart disease or have a stroke. You’re also at high risk of blocked blood vessels (atherosclerosis) and chest pain (angina).
Kidneys. If your kidneys are damaged or you have kidney failure, you could need dialysis or a kidney replacement.
Eyes. High blood sugar can damage the tiny blood vessels in the backs of your eyes (retinopathy). If this isn’t treated, it can cause blindness.
Nerves. This can lead to trouble with digestion, the feeling in your feet, and your sexual response.
Skin. Your blood doesn’t circulate as well, so wounds heal slower and can become infected.
Pregnancy. Women with diabetes are more likely to have a miscarriage, a stillbirth, or a baby with a birth defect.
Sleep. You might develop sleep apnea, a condition in which your breathing stops and starts while you sleep.
Hearing. You’re more likely to have hearing problems, but it’s not clear why.
Brain. High blood sugar can damage your brain and might put you at higher risk of Alzheimer’s disease.
Depression. People with the disease are twice as likely to get depressed as people who don’t have it.

The best way to avoid these complications is to manage your type 2 diabetes well.

Take your diabetes medications or insulin on time.
Check your blood sugar.
Eat right, and don’t skip meals.
See your doctor regularly to check for early signs of trouble.

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Build Your Health Care Team

There are many medical professionals who can help you live well with diabetes, including:

Endocrinologists
Nurses
Registered dietitians
Pharmacists
Diabetes educators
Foot doctors
Eye doctors
Dentists

10 Questions to Ask Your Doctor About Diabetes

If you were recently diagnosed with type 2 diabetes, ask your doctor these questions at your next visit.

Does having diabetes mean that I am at higher risk for other medical problems?
Should I start seeing other doctors regularly, such as an eye doctor?
How often should I test my blood sugar, and what should I do if it is too high or too low?
Are there any new medications that I could use to help manage my diabetes?
Does diabetes mean I have to stop eating the foods I like best?
How can exercise make a difference in my diabetes?
If I’m overweight, how many pounds do I have to lose to make a difference in my health?
Are my children at increased risk for the disease?
What is the importance of diet in diabetes?
Do I need to take my medications even on days that I feel fine?

November 14, 2020

Don’t let glaucoma steal your vision

Overview

Open-angle glaucomaOpen pop-up dialog box

Glaucoma is a group of eye conditions that damage the optic nerve, the health of which is vital for good vision. This damage is often caused by an abnormally high pressure in your eye.

Glaucoma is one of the leading causes of blindness for people over the age of 60. It can occur at any age but is more common in older adults.

Many forms of glaucoma have no warning signs. The effect is so gradual that you may not notice a change in vision until the condition is at an advanced stage.

Because vision loss due to glaucoma can’t be recovered, it’s important to have regular eye exams that include measurements of your eye pressure so a diagnosis can be made in its early stages and treated appropriately. If glaucoma is recognized early, vision loss can be slowed or prevented. If you have the condition, you’ll generally need treatment for the rest of your life.

Symptoms

The signs and symptoms of glaucoma vary depending on the type and stage of your condition. For example:

Open-angle glaucoma

Patchy blind spots in your side (peripheral) or central vision, frequently in both eyes
Tunnel vision in the advanced stages

Acute angle-closure glaucoma

Severe headache
Eye pain
Nausea and vomiting
Blurred vision
Halos around lights
Eye redness

If left untreated, glaucoma will eventually cause blindness. Even with treatment, about 15 percent of people with glaucoma become blind in at least one eye within 20 years.

REQUEST AN EYE EXAMINATION AT EYEUPDATE CLINIC

When to see a doctor

Promptly go to an emergency room or an eye doctor’s (ophthalmologist’s) office if you experience some of the symptoms of acute angle-closure glaucoma, such as severe headache, eye pain and blurred vision.

Causes

Glaucoma is the result of damage to the optic nerve. As this nerve gradually deteriorates, blind spots develop in your visual field. For reasons that doctors don’t fully understand, this nerve damage is usually related to increased pressure in the eye.

Elevated eye pressure is due to a buildup of a fluid (aqueous humor) that flows throughout the inside of your eye. This internal fluid normally drains out through a tissue called the trabecular meshwork at the angle where the iris and cornea meet. When fluid is overproduced or the drainage system doesn’t work properly, the fluid can’t flow out at its normal rate and eye pressure increases.

Glaucoma tends to run in families. In some people, scientists have identified genes related to high eye pressure and optic nerve damage.

Types of glaucoma include:

Open-angle glaucoma

Open-angle glaucoma is the most common form of the disease. The drainage angle formed by the cornea and iris remains open, but the trabecular meshwork is partially blocked. This causes pressure in the eye to gradually increase. This pressure damages the optic nerve. It happens so slowly that you may lose vision before you’re even aware of a problem.

Angle-closure glaucoma

Angle-closure glaucoma, also called closed-angle glaucoma, occurs when the iris bulges forward to narrow or block the drainage angle formed by the cornea and iris. As a result, fluid can’t circulate through the eye and pressure increases. Some people have narrow drainage angles, putting them at increased risk of angle-closure glaucoma.

Angle-closure glaucoma may occur suddenly (acute angle-closure glaucoma) or gradually (chronic angle-closure glaucoma). Acute angle-closure glaucoma is a medical emergency.

Normal-tension glaucoma

In normal-tension glaucoma, your optic nerve becomes damaged even though your eye pressure is within the normal range. No one knows the exact reason for this. You may have a sensitive optic nerve, or you may have less blood being supplied to your optic nerve. This limited blood flow could be caused by atherosclerosis — the buildup of fatty deposits (plaque) in the arteries — or other conditions that impair circulation.

Glaucoma in children

It’s possible for infants and children to have glaucoma. It may be present from birth or develop in the first few years of life. The optic nerve damage may be caused by drainage blockages or an underlying medical condition.

Pigmentary glaucoma

In pigmentary glaucoma, pigment granules from your iris build up in the drainage channels, slowing or blocking fluid exiting your eye. Activities such as jogging sometimes stir up the pigment granules, depositing them on the trabecular meshwork and causing intermittent pressure elevations.

REQUEST AN EYE EXAMINATION AT EYEUPDATE CLINIC

Risk factors

Because chronic forms of glaucoma can destroy vision before any signs or symptoms are apparent, be aware of these risk factors:

Having high internal eye pressure (intraocular pressure)
Being over age 60
Being black, Asian or Hispanic
Having a family history of glaucoma
Having certain medical conditions, such as diabetes, heart disease, high blood pressure and sickle cell anemia
Having corneas that are thin in the center
Being extremely nearsighted or farsighted
Having had an eye injury or certain types of eye surgery
Taking corticosteroid medications, especially eyedrops, for a long time

Prevention

These self-care steps can help you detect glaucoma in its early stages, which is important in preventing vision loss or slowing its progress.

Get regular dilated eye examinations. Regular comprehensive eye exams can help detect glaucoma in its early stages, before significant damage occurs. As a general rule, the American Academy of Ophthalmology recommends having a comprehensive eye exam every five to 10 years if you’re under 40 years old; every two to four years if you’re 40 to 54 years old; every one to three years if you’re 55 to 64 years old; and every one to two years if you’re older than 65. If you’re at risk of glaucoma, you’ll need more frequent screening. Ask your doctor to recommend the right screening schedule for you.
Know your family’s eye health history. Glaucoma tends to run in families. If you’re at increased risk, you may need more frequent screening.
Exercise safely. Regular, moderate exercise may help prevent glaucoma by reducing eye pressure. Talk with your doctor about an appropriate exercise program.
Take prescribed eyedrops regularly. Glaucoma eyedrops can significantly reduce the risk that high eye pressure will progress to glaucoma. To be effective, eyedrops prescribed by your doctor need to be used regularly even if you have no symptoms.
Wear eye protection. Serious eye injuries can lead to glaucoma. Wear eye protection when using power tools or playing high-speed racket sports in enclosed courts.

October 1, 2020

Health benefits of bitter kola

Did you know that Coca-Cola got its name from a common African tree?

Some of the first recipes for Coca-Cola were made using the extract of the bitter kola plant. Though the company hasn’t used actual kola to flavor their sodas in years, the name remains a reminder of the unusual plant that inspired the iconic drink.

Bitter kola, also known as bitter cola or Garcinia Kola, is a plant found in Central and Western Africa that has long been valued for its medicinal properties. Although traditional African medicine uses all parts of the Bitter Kola plant, the seeds are mostly commonly eaten.

Bitter kola seeds have a sharp, bitter flavor that eases into a slight sweetness as you chew, and they’re typically eaten raw.

Health Benefits

Although bitter kola has been eaten in Africa for years, scientists are just beginning to study the health benefits of this flowering plant.

According to these early studies, bitter kola may be able to help with health problems including:CONTINUE READING BELOW

Infections

Bitter kola has been used over the years to fight infections from the common cold to hepatitis. A 2018 study showed that bitter kola can help combat coughs, bacterial infections, and viral infections. Eating bitter kola when an infection starts may help fight the infection and make you feel better more quickly.

Inflammation

Bitter kola seeds have commonly been chewed on in Africa to fight against inflammatory conditions like arthritis. One 2008 study showed that patients with osteoarthritis in their knees showed significantly reduced inflammation when eating bitter kola compared to a placebo. The high levels of potassium in bitter kola may be a contributing factor in reducing inflammation.

Diabetes

Early studies suggest that a chemical called kolaviron, which is found in bitter kola, may protect against hypoglycemia in people with type 2 diabetes. Although this first study was done on rats and has not yet been reproduced on humans, these early findings are promising.

Nutrients per Serving

The FDA considers bitter kola generally safe to eat, but classifies it similarly to essential oils. That means there’s not much information available about serving sizes or nutritional data. However, a 2013 study found that bitter kola was high in the following nutrients:

Carbohydrates
Fat
Protein

The study same study also found that bitter kola had high levels of:

Vitamin C
Calcium
Potassium
Iron
Caffeine

How to Prepare Bitter Kola

Bitter kola can be eaten on its own, uncooked, like many other nuts. Keep in mind, however, that it’s called “bitter” for a reason. Bitter kola can be an acquired taste.

You can sometimes find drinks made or flavored with bitter kola at African markets and online stores. If you don’t like the taste but want to introduce bitter kola to your diet, these drinks may be a good option.

September 17, 2020

Road safety and your eyesight

Uncorrected vision continues to endanger the lives of drivers, passengers, and pedestrians around the world. Compounded by external factors such as nighttime driving, inclement weather, and adverse road conditions, uncorrected vision contributes to more than 1.25 million road accident deaths each year.[1] Until recently, the intersection of vision and road safety has not received adequate attention. Consequently, there is a lack of awareness around the need to address the impact of vision problems on driver and road safety. While governments and policymakers can play a significant role in raising greater awareness of this public health threat, eye care professionals are also part of the solution as they are a competent authority in promoting effective assessment of vision and correcting drivers’ visual functions.CONTENT KEY TAKEAWAYS REFERENCES

The problematic relationship between uncorrected vision and road safety is a deadly, global phenomenon, and is growing more dangerous. The World Health Organization (WHO) has reported that road traffic crashes are a leading cause of road deaths globally and the main cause of deaths among those aged 15 to 29 years-old.[2] What is perhaps most disturbing is how traffic accidents disproportionately affect low- or middle-income countries, which are home to more than 80 percent of the world’s population. Though these countries account for only 54 percent of the world’s vehicles, they see 90 percent of all road traffic deaths. These road accidents also come with an adverse economic impact, estimated at US$500 billion a year –another burden on low- or middle-income countries. [2]

“These road accidents also come with and adverse economic impact, estimated at US$ 500 Billion a year – another burden on low- or middle-income countries.”

There are hopeful signs, yet much work remains. Globally, the number of traffic deaths plateaued between 2007 and 2015 despite a four percent increase in the world’s population – and an increase in motorization even four times higher than that – suggesting that intervention efforts can and do save lives. [2] However, disparity remains. Among the 68 countries that saw a rise in the number of road traffic deaths between 2010 and 2013, 84 percent were low- or middle-income.[2]

Recognizing the severity and disparity of both the human toll and economic burden that traffic accidents place on national economies and individual households alike, the United Nations, in its Sustainability Goals, included an ambitious goal of halving traffic-related deaths and injuries by the year 2020.

This new imperative to address road safety brings with it a greater urgency to understand the underlying causes of traffic accidents. Much attention has been given to the effects of drunk driving and, more recently, the use of wireless devices while driving. But in addition to the important issues of inebriated and inattentive driving, vision impairment also warrants attention.

The assumption of good vision, necessary to safely operate a vehicle, has long caused uncorrected vision to be overlooked as a factor in road safety. Drs. Cynthia Owsley and Gerald McGwin note in their analysis, “Vision and Driving,” that “the visual demands of driving are intricate.” [3] By cataloging the many and varied visual tasks involved in driving, including the simultaneous use of central and peripheral vision to monitor primary and secondary tasks, they reinforce how visually intensive driving under normal conditions is. These findings have led researchers to conclude that many visual tests for drivers are inadequate, often failing to simulate the distractions and wide ranging contrast and luminance levels experienced in real-world road conditions.[3] This is compounded by the fact that many drivers avoid seeking evaluation and treatment for vision issues; in Europe, 19 percent of drivers reported delaying visits to an optician until they notice problems with their vision.[5]

Driving and vision infographics Vision Impact Institute - Points De Vue

The contributions of Owsley, McGwin, Chakrabarty and others to the growing dialogue around driving and vision are indicative of the increased attention and analysis that this issue requires. However, though the link between vision and road safety should be a global concern, the disparity between high-income and low- or medium-income countries illustrates that it remains very much a local issue, which demands a greater understanding of local factors.

Road Safety Around the World

As the correlation between vision and road safety has come to the forefront, more data is becoming available from both high-income and low- or medium-income countries.

In India, for example, the dual forces of population growth and economic development have resulted in a higher number of vehicles on the road and, consequently, a greater number of traffic accidents. One study of vision and drivers in India calculated the road crash involvement rate of drivers with unacceptable vision test results at 81 percent, which was 30 percent higher than that of drivers with good vision.[6] While many factors, including poor vehicle and road conditions and traffic violations, have been found to affect driver safety, researchers have pointed to vision problems, worsened by night driving, as significant causes of driver safety challenges.

As the correlation between vision and road safety has come to the forefront, more data is becoming available from both high-income and low- or medium-income countries.

In India, for example, the dual forces of population growth and economic development have resulted in a higher number of vehicles on the road and, consequently, a greater number of traffic accidents. One study of vision and drivers in India calculated the road crash involvement rate of drivers with unacceptable vision test results at 81 percent, which was 30 percent higher than that of drivers with good vision.6 While many factors, including poor vehicle and road conditions and traffic violations, have been found to affect driver safety, researchers have pointed to vision problems, worsened by night driving, as significant causes of driver safety challenges.

Despite the disproportionate impact of uncorrected vision on road safety in low- or medium-income countries, high-income countries are not immune to this threat. A 2003 European analysis of health-related risk factors in traffic accidents found that the risk of car crash increased by nine percent when there was a visual impairment.[7] Research also reveals how even a relatively small percentage of drivers with uncorrected vision can cause a significant economic impact. In the U.K., for example, only seven percent of the population suffers from uncorrected vision, yet the economic impact of road accidents in relation to vision amounted to US$55 million in 2012.[9,13]

Vision Solution Efforts

Though uncorrected vision remains a danger to road safety, recent research is helping to make the case for policies and resources that can put the brakes on this global public health threat. With more stakeholders undertaking efforts to understand the intersection of vision and road safety, researchers, governments, organizations and eye care professionals around the world are beginning to identify promising solutions. In Italy, researchers evidenced that the use of an appropriate ophthalmic compensation with corrective lenses is able to improve drivers’ visual abilities.[10] In India, for instance, as the result of early efforts to prevent traffic accidents, drivers are now required to undergo vision screenings and be granted access to driving aids such as anti-glare glasses.[4]

Based on their research, Drs. Owsley and McGwin recommend additional screening measures to augment current visual acuity tests, which would examine drivers’ contrast sensitivity, visual field, processing speed, and divided attention. But most importantly, they call for more research methodology on vision and driving to expand upon the current database of knowledge.[3]

However, more research, more testing and even more rigorous testing will not reduce the threat of uncorrected vision on road safety if drivers do not seek evaluation and treatment from eye care professionals. The WHO released a report, “Universal Eye Health: A Global Action Problem 2014-2019,” which focuses on finding solutions to visual impairments. According to the report, if vision care – such as refractive services and surgeries – were provided, more than two-thirds of people affected by uncorrected vision could improve their eyesight.[11]

For this reason, organizations like Essilor and the Fédération Internationale de I’Automobile (FIA) have pledged to address the correlation between poor vision and driver and road safety. Essilor’s role in the partnership is to advocate for road safety and reinforce FIA’s messages about the vital role of adequate vision along with corresponding efforts to lobby against road accidents and deaths. The collaboration between these two organizations rests on the “New Golden Rule, ‘Check your vision,’” which aims to raise awareness on vision as a public health challenge by updating FIA’s ten “Golden Rules” on road safety. This partnership received the distinct endorsement of the World Council of Optometry and the Vision Impact Institute at the 2nd World Congress of Optometry in Sept. 2017.[12]

Conclusion

It is imperative that we address vision problems and their impact on the safety of drivers, passengers, and pedestrians. Vision standards for driving must be a priority, and the development and implementation of these standards should not fall solely on local, state and national governments, but also on eye care professionals around the world. As we work towards our goal of expanding access to proper vision care around the world, our success will hinge on the collaboration between stakeholders to identify solutions that will improve driver vision, equip medical professionals with the information and resources they need and, ultimately, ensure road safety for drivers everywhere.

“It is imperative that we address vision problems and their impact on the safety of drivers, passengers, and pedestrians.”