Layers of the Retina

The retina at the back of the eye is essential for all vision. Each layer of cells in this tissue serves a specific purpose. As we prepare for Age-Related Macular Degeneration Awareness Month in February, a closer look at the layers of the retina and their function.

Layers of the Retina

Choroid – This is made up of a layer of blood vessels that supply oxygen and nutrients to the retina. Defect in the CHM gene can cause choroideremia, leaky blood vessels can expand in the retina causing wet age-related macular degeneration (AMD) and diabetic retinopathy.

Retinal pigment epithelium – This is a single layer of cells that provide essential nutrition and waste removal for the photoreceptor cells. Accumulation of waste can lead to AMD and Stargardt disease.

Photorecptors – This is where the rods and cones are located that convert light into electrical signals. Rods help you with night and peripheral vision. Cones are more concentrated in the macula (the central part of the retina) and proved central and color vision. Death of the rods can cause vision loss called retinitis pigmentosa, while AMD is the loss of central vision.

Horizontal cells – These cells are connect to the photoreceptors that surround the bipolar connected photoreceptor cells and help the help integrate and regulate the input from multiple photoreceptor cells, increasing your visual acuity.

Bipolar cells – The dependence of each layer of the retina on each other is exemplified here. These cells take the electrical information from the photoreceptor cells and pass it along to other retinal cells.

Ganglion cells – These cells extend to form an optic nerve that conveys information to the brain and take the electrical information from the bipolar cells and process it to determine shapes, contrast and color. Glaucoma vision loss results from high intraocular pressure that affects the optic nerve, interrupting the signals to the brain.

Mitochondria and Age-Related Macular Degeneration

Research on mitochondrial DNA shows promise for treating AMD

For the past few years, DEF Research Director Dr. M. Cristina Kenney has been researching the relationship of mitochondria and age-related macular degeneration (AMD). She found that damaged mitochondria from people with AMD send signals that can cause retinal cells to die at an increased rate, compared with people who had healthy mitochondria and no AMD. That research led to the exploration of stimulating mitochondria to support retinal cell health in an effort to retain or restore vision for people with AMD.

Mitochondria in Cells
Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy and carry out specialized functions. Cells also contain the body’s hereditary material (DNA) and so they can make copies of themselves.

Mitochondria are tiny structures inside cells whose function is to produce energy, like a battery in a flashlight, to keep cells alive. Each cell contains hundreds to thousands of mitochondria, which are located in the fluid that surrounds the nucleus. Although most DNA is packaged in chromosomes within the nucleus of a cell (nuclear DNA), mitochondria also have a small amount of their own DNA, known as mitochondrial DNA or mtDNA.

Because only egg cells contribute mitochondria to a developing embryo, only females can pass on the mitochondrial DNA to their children.

Mitochondrial Haplogroups
The mtDNA can be classified into categories called haplogroups, which represent different ancient, geographically separated groups of people. For example, African-Americans and people of ancient African lineage have inherited L haplogroup mitochondria from their mothers no matter where they currently live.

Similarly, most Ashkenazi Jewish populations (primarily those Jews whose families originated in Eastern or Central Europe) possess mitochondria of the K haplogroup. People with this haplogroup of mtDNA seem to be susceptible to a variety of age-related diseases, including age-related macular degeneration (AMD).

The incidence of AMD varies a lot among different ethnic/racial populations. For example, in the United States, the likelihood of losing vision from AMD is very low for a person with an African maternal background but it is much higher in people of European descent. Similarly, in an Israeli eye clinic, of the people who had AMD, 96% were Jewish while only 4% were of Arab descent. This suggests that European mtDNA in retinal cells of Caucasians may be the reason they are more susceptible to AMD.

Mitochondria and Age-Related Macular Degeneration — Figure 1

It has been recognized that AMD is a very complex disease with many factors involved (Figure 1). There are more than 30 genes associated with AMD, representing many different biological pathways. In addition, mitochondrial damage and specific mtDNA haplogroups have been associated with AMD. Finally, it is recognized that environmental factors, such as smoking and obesity, increase the risk to develop AMD.

Although millions of dollars and thousands of man-hours have been invested in finding the causes and treatments for AMD, we still do not understand how to prevent the most common form of AMD. One major difficulty has been that when we study a diverse group of individuals, each with hundreds of different nuclear and mitochondrial genes, it is very difficult to identify the causes and pathways involved with developing AMD and determining effective treatments. One drug may not help everyone and different people develop different types and severities of AMD.

Kenney’s approach to this dilemma has been to SIMPLIFY THE TESTING SYSTEM (Figure 2). In her research with different ethnic/racial groups, Kenney has found that the Ashkenazi Jewish population (K haplogroup) is an excellent group in which to study age-related diseases. This group has very well characterized nuclear and mitochondrial genes, the population tends to relatively homogenous and to marry within their community. Finally, the Ashkenazi Jewish population has longevity, which increases the likelihood that they will develop aging diseases, such as AMD.

Kenney’s laboratory has created a “cybrid” test system, which are cell lines with identical nuclei and nuclear DNA, but different mitochondrial DNA so that the differences in the cell behavior can be attributed to the different mitochondrial DNA (see the following cybrid story on 11/17/15). Using the cybrid system, Kenney has compared cell behavior of mitochondria from subjects with the K (Ashkenazi Jewish) haplogroups and the mitochondria from people of the H haplogroup (Figure 3), the most common European haplogroup.

There are:

Major differences in production of cholesterol and lipid molecules
Altered levels of inflammation
Differences in their responses to toxic effects of amyloid-? (a toxic protein associated with AMD and Alzheimer’s disease)

These differences are important contributors to AMD and other age-related diseases.

Significance of the Findings
Maternally inherited mitochondrial DNA can influence how a person’s cells respond to stress and this can contribute to age-related diseases. This is a completely new way of thinking about common aging diseases and offers new approaches to treatment and prevention of those diseases.

Future Studies
Kenney’s laboratory will continue to use the K haplogroup cybrid model to study the mitochondrial DNA, with the goal of blocking the harmful events that cause early retinal cell death, such as that seen in AMD. An additional advantage of cybrids is that they are unique to the donor whose blood was used to make them. Therefore with these “personalized cybrids,” Kenney can test the responses of the personalized cybrids to drugs that are currently being used for AMD (Lucentis™, Avastin™ and Eylea™). They can also be used to identify novel, new drugs that can protect the cells from early cellular death, a major event in the dry form of AMD. This research shows great promise in developing personalized treatments for AMD and other age-related diseases.

11/12/15

Anthony B. Nesburn, MD FACS
President/Medical Director
Discovery Eye Foundation

The Importance of An Eye Exam

Why You Need An Eye Exam

The end of the year is fast approaching – when was the last time you had an eye exam? Was it a comprehensive eye exam?

To keep your eyes healthy and maintain your vision, the American Optometric Association (AOA) recommends a comprehensive eye exam every two years for adults ages 18 to 60, and annual exams for people age 61 and older. However, if you have a family history of eye disease (glaucoma, macular degeneration, etc.), diabetes or high blood pressure, or have had an eye injury or surgery, you should have a comprehensive exam every year, unless otherwise indicated by your doctor.
Also, adults who wear contact lenses should have annual eye exams.

An important part of the comprehensive eye exam is the dilated eye exam to look inside your eye. Drops are placed in each eye to widen the pupil and allow more light to enter the eye. This gives your doctor a clear view of important tissues at the back of the eye, including the retina, the macula, and the optic nerve. This allows for early diagnosis of sight-threatening eye diseases like age-related macular degeneration, diabetic retinopathy, glaucoma, etc.

To better understand the importance of the dilated eye exam, here is a video from the National Eye Institute (NE) that explains what to expect.

At the end of your comprehensive eye exam your doctor should raise any concerns he has with you. But it is up to you to be prepared to react and ask questions for peace of mind and to help save your vision.

Questions To Ask After Your Eye Exam

It is always important to know if anything about your eyes have changed since your last visit. If the doctor says no, then the only thing you need to know is when they want to see you again.

If the doctor says the have been some minor changes, you need to know what questions to ask, such as:

Is my condition stable, or can I lose more sight?
What new symptoms should I watch out for?
Is there anything I can do to improve or help my vision?
When is the next time you want to see me?

If the doctor sees a marked change in your vision or give you a diagnosis of eye disease, you would want to ask:

Are there treatments for my eye disease?
When should I start treatment and how long will it last?
What are the benefits of this treatment and how successful is it?
What are the risks and possible side effects associated with this treatment?
Are there any foods, medications, or activities I should avoid while I am undergoing this treatment?
If I need to take medication, what should I do if I miss a dose or have a reaction?
Are there any other treatments available?
Will I need more tests necessary later?
How often should I schedule follow-up visits? Should I be monitored on a regular basis?
Am I still safe to drive?

Your vision is a terrible thing to lose, but with proper diet, exercise and no smoking, along with regularly scheduled eye exams, you improve your chances of maintaining your sight.

11/5/15

Susan DeRemer, CFRE

Best’s Disease

In 1905, Friedrich Best presented a detailed pedigree of an inherited retinal condition referred to as vitelliform dystrophy, or Best’s disease. Best’s disease is an inherited dystrophy of the macula that primarily involves cells known as retinal pigment epithelium (RPE).

Best’s typically affects both eyes and presents itself either in childhood or early adulthood. Visual acuity is usually minimally affected early on in the course. As the condition progresses, the vision can slowly begin to deteriorate. The rate of progression or the overall amount of progression is difficult to predict. The rate of progression may be also be asymmetric, with one eye progressing at a different rate than the other. Some patients may notice the development of scotoma, or “blind spot”, in their central vision as the condition progresses. Other patients may not progress to later stages or experience vision loss. Loss of peripheral, or side vision, is not expected with Best’s.

The diagnosis of Best’s disease is primarily based on a careful clinical exam. Taking a careful family history is also important as Best’s is typically inherited in an autosomal dominant pattern. This means that an affected individual has a 50 percent chance of passing the gene to their offspring. It should be noted though that there is highly variable expression, which means there may be some affected individuals in whom the changes are so mild that they never notice any visual disturbance. The causative gene is located on chromosome 11 and has been labeled BEST1 (VMD2). This encodes for a protein known as bestrophin 1, which is located on the membrane of RPE cells. It is believed that this protein is involved in RPE metabolism through its control of chloride channels, although the details are still being elucidated. Thus far, there have been over 200 mutations of the BEST1 gene that have been described.

The classic exam finding in Best’s is a circular yellow lesion in the macula. This lesion resembles an “egg-yolk”, and is often referred to as such by ophthalmologists. As the condition progresses, the yellow material begins to break up and the pigmentation of the macula attains a more mottled appearance. This is often referred to as a “scrambled egg” appearance. After many years, there may be evidence of cell loss in the macula, which can negatively impact the visual acuity. In a relatively small proportion of cases, a complication can occur in which abnormal blood vessels grow underneath the macula and begin to leak fluid and/or blood into the macula. This is known as choroidal neovascularization (CNV), and can be vision threatening. Fortunately , CNV can be treated effectively with medications that are injected into the eye as part of a straightforward and low-risk office procedure. Typical signs of CNV would include distortion or blurring of the vision, and it is important to notify your doctor of any sudden changes in vision.

Diagnostic testing is sometimes used to confirm the diagnosis. The electro-oculogram (EOG) is universally abnormal in Best’s, and can be a valuable confirmatory test. Fluorescein angiography and optical coherence tomography can be valuable tests to better evaluate the macula and to also look for the development of CNV. Genetic testing for Best’s is now possible as well.

There is no established medical or surgical management for Best’s disease. In patients who develop CNV as a secondary complication, existing treatment options are effective. Future avenues of therapy hold significant promise, but are in their early stages of development. Stem cell based therapies, for example, have the potential to help restore healthy cells that may have been lost during the disease progression.

10/29/15

Daniel D. Esmaili, MD
Retina Vitreous Associates Medical Group

Increased Awareness for Saving Vision

The following is a survey done by Essilor (a French company that produces ophthalmic lenses along with ophthalmic optical equipment) and a large marketing research firm in the UK, YouGov. While the focus in on people living in the UK, the results would probably be similar to the US population. Even with increased access to the Internet, many people are still not aware of the risks associated with eye disease and what they can do to help retain their vision. Increased awareness of informational resources are important for saving vision.

There are a number of websites with easy to understand information about taking care of your vision that I have listed under Resources to Help Save Vision at the bottom of this article. And while there are eye diseases that are hereditary, you can slow the onset and progression by making good lifestyle choices about smoking, diet and exercise. Your eye care specialist is also an excellent source of information about what you can to do reduce your risk of vision loss, at any age.

Increased Awareness for Saving Vision

A YouGov poll conducted with Essilor reveals that most Britons are unaware of damage to their eyes by surrounding objects, activities, and devices. This widespread lack of awareness means fewer people seeking methods of prevention and avoidance, and for those that are aware of risks, most are not informed of existing preventative measures.

The poll has shown* that many British people remain uninformed about the various ways in which eyes are damaged by common daily factors, despite evidence that eye health is affected by blue light, UV rays (reflected from common surfaces), diet, obesity, and smoking.
Of the 2,096 people polled, the percentage of respondents aware of the link between known factors affecting and eye health were:

Poor diet – 59%
Obesity – 35%
Smoking tobacco – 36%
UV light, not just direct from the sun but reflected off shiny surfaces – 54%
Blue light from low energy lightbulbs and electronic screens – 29%

More than one in ten people were completely unaware that any of these factors could affect your eyesight at all.

72% of respondents own or wear prescription glasses but only 28% knew that there were lenses available (for both prescription and non-prescription glasses) to protect against some of these factors; specifically, blue light from electronic devices and low energy light bulbs, and UV light from direct sunlight and reflective surfaces.

76% admitted they haven’t heard of E-SPF ratings – the grade given to lenses to show the level of protection they offer against UV.

Just 13% have lenses with protection from direct and reflected UV light, and only 2% have protection from blue light (from screens, devices, and low energy bulbs).

Poll results showed that younger people were most aware of the dangers of UV and blue light, yet least aware of how smoking tobacco and obesity can affect your eye health. Within economic sectors, middle to high income people are more aware of the effects of smoking & obesity on eyesight than those with low income –

39% of people with middle to high income compared to 33% of people with low income are aware of the impact of smoking tobacco.
38% of people with middle to high income compared to 31% of people with low income are aware of the impact of obesity.

Awareness of the impacts of smoking and obesity on eye health is significantly higher in Scotland (47% & 49% respectively) than anywhere else in the UK (35% & 33% in England and 40% & 38% in Wales).
Essilor’s Professional Relations Manager, Andy Hepworth, has commented: “The lack of awareness about these common risks to people’s eyes is concerning. Not only would many more glasses wearers be better protected, but also many people who do not wear glasses would likely take precautions too, if made aware of the dangers and the existence of non-prescription protective lenses.”

To see the full results of the poll, please visit the Essilor website.

For more information on the protection offered from blue light and UV through specialist lens coatings, for both prescriptions and non-prescription glasses, please see here for UV & Blue Light Protection options.

*All figures, unless otherwise stated, are from YouGov Plc. Total sample size was 2,096 adults. Fieldwork was undertaken between 21st and 24th August 2015. The survey was carried out online. The figures have been weighted and are representative of all GB adults (aged 18+).

Resources To Help Save Vision
All About Vision
Macular Degeneration Partnership
National Eye Institute (NEI)
Prevent Blindness

10/16/15

Susan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

Retinal Vascular Occlusions

Just like any other organ in the body, the retina needs a healthy blood supply to function properly. When a blood vessel in the retina becomes blocked, sudden loss of vision can occur. Such blockages, known as retinal vascular occlusions, often occur in older adults. Because there are effective treatments available, seeing a specialist promptly can prevent further problems or even restore vision.

Retinal arterial occlusions

Arteries are the vessels that bring fresh blood containing oxygen and nutrients to different parts of the body. The artery that supplies the retina is known as the central retinal artery. After it enters the eye, the central retinal artery splits up into branch retinal arteries that serve different areas of the retina.

Symptoms
The symptoms of a central retinal artery occlusion include a sudden, painless loss of vision in one eye. Because the circulation to the entire retina is disrupted, the vision loss is profound and encompasses the entire field of vision. In contrast, a branch retinal artery occlusion only leads to loss of vision in a part of the field of vision. This is because only part of the retinal circulation in compromised. Similar to a central retinal artery occlusion, a branch retinal artery occlusion is also typically sudden and painless.

Evaluation
Retinal arterial occlusions can usually be diagnosed simply by examining the retina. Often, the retina is whitened in the area of the occlusion due to the lack of blood flow. Most arterial occlusions occur in patients with diseases such as high blood pressure or diabetes. On occasion, fragments of cholesterol or blood clots can be cause of the occlusion. Therefore, the treating physician will usually order tests looking for the source of these deposits in the carotid arteries or the heart. Another important cause of central retinal artery occlusions is a condition known as temporal arteritis. Temporal arteritis is an inflammatory disorder that can also produce fever, pain, or weight loss. Blood tests are ordered if temporal arteritis is suspected.

Retinal vascular occlusions — Figure 1. Whitening of the retina due to a central retinal artery occlusion

Treatment
Unfortunately, there is no proven, reliable treatment for retinal arterial occlusions at this time. Various methods including hyperbaric oxygen, ocular massage, and anterior chamber paracentesis may or may not be effective if the occlusion is treated right away. However, if the occlusion is due to temporal arteritis, treatment with corticosteroids is effective at preventing loss of vision in the other eye. An unwanted, late complication of retinal arterial occlusions is neovascularization. Neovascularization refers to the growth of new, abnormal blood vessels in different parts of the eye that can result in bleeding, detachment of the retina, or glaucoma. Neovascularization is treated with laser or injections of anti-neovascular medications into the eye.

Retinal venous occlusions

After blood has passed into the eye through the retinal arteries, it leaves through the retinal veins. Blood travels first through the smaller, branch retinal veins and then enters the central retinal vein.

Symptoms
A central retinal vein occlusion usually causes sudden, painless vision loss in one eye. Unlike a central retinal artery occlusion, which causes profound vision loss, the visual deficit in a central retinal vein occlusion can range from mild to severe. More severe occlusions cause more severe deprivation of vital oxygen to retinal tissue. In addition, a central retinal occlusion can result in macular edema, swelling of the retina that also leads to blurred vision. A branch retinal vein occlusion usually leads to blurring of vision in only part of one eye. Like central retinal vein occlusions, branch retinal vein occlusions can vary in severity, but often result in macular edema as well.

Evaluation
Retinal venous occlusions are also diagnosed by examining the retina. The blocked vein will appear dilated and engorged. In addition, the area of the retina served by that vein will contain hemorrhages or become swollen. To assess the amount of oxygen deprivation to the retina, a specialist will often recommend a fluorescein angiogram. The angiogram involves the injection of a yellow dye known as fluorescein intravenously. Subsequent photos allow visualization of the abnormal blood flow within the retina. In addition, optical coherence tomography is often performed to determine the amount of swelling within the retina.

Figure 2. A retinal vein occlusion with hemorrhages seen as the red spots in the bottom half of the image.

Treatment
Treatment of retinal venous occlusions is largely aimed at decreasing swelling in the macula in hopes of improving vision. Currently, the most effective treatments involve injections of medication into the eye. FDA approved medications such as Lucentis and Eylea, that target abnormal levels of growth factors in the eye, can result in significant gains in vision in approximately two thirds of patients with branch retinal vein occlusions and half of patients with central vein occlusions. In addition, injectable steroid medications such as Ozurdex can also be effective, with approximately one third of patients having a significant visual gain. Laser can also be used to treat macular edema due to branch retinal vein occlusions. Keep in mind that these treatments likely need to be repeated on a routine basis or used in combination to achieve maximum benefits. If neovascularization occurs, it is treated as previously described in the section about retinal arterial occlusions.

In conclusion, occlusions of either retinal arteries or veins can cause significant visual impairment. Prompt evaluation and ongoing treatment with a retinal specialist can often improve and maintain vision.

9/24/15

David Liao, MD, PhD
Retina-Vitreous Medical Group

Which Eye Care Specialist Do You Need?

It’s time to get your eyes checked – do you go to an ophthalmologist, optometrist or optician? Your optometrist sees the beginnings of age-related macular degeneration, but is sending you to see and ophthalmologist, why?

One of the most confusing things about taking care of your eyes can be differentiating between an ophthalmologist, optometrist and optician. Each eye care specialist has a very important part to play in the health of your eyes and here is a quick synopsis of what each does so you can choose the best one for your vision issues and treatment.

Ophthalmologist
These specialists are fully trained medical doctors that have completed the eight years of training beyond a bachelor’s degree. Their training has included a full spectrum of eye care, from prescribing glasses and contact lenses and giving eye injections, to carrying out intricate eye surgeries. Many doctors may also be involved eye research to better understand vision, improve eye disease treatments or potentially find a cure. They are easily identified by the MD following their name.

Optometrist
These medical professionals have completed a four-year program at an accredited school of optometry. They have been trained to prescribe and fit glasses and contact lenses, as well as diagnose and treat various eye diseases. They provide treatments through topical therapeutic agents and oral drugs, and are licensed to perform certain types of laser surgery, such as Lasik. They are easily identified by the OD following their name.

Optician
These eye care professionals are not licensed to perform eye exams, medical tests or treat patients. Their purpose is to take the prescription from the ophthalmologist or optometrist and work with you to determine which glasses or contact lenses work best for you. If you suffer from an eye disease like keratoconus, these specialists can make the difference between a relatively normal life, or one that is dictated short periods of vision because of contact lens pain. These eye care professionals may hold and associate optician degree or have apprenticed fore required number of hours.

While each one of these eye specialists has their own area of expertise, they can form a team whose only concerns are your eye health and the ability to see as clearly as possible.

8/11/15

Susan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

Eye Issues For Every Age Recap

Vision is something we take for granted, but when we start to have trouble seeing it is easy to panic. This blog has covered a variety of eye issues for every age, from children through older adults. Here are a few articles from leading doctors and specialists that you may have missed and might be of interest.

Bill Takeshita, OD, FAAO – Visual Aids and Techniques When Traveling

Michelle Moore, CHHC – The Best Nutrition for Older Adults

Arthur B. Epstein, OD, FAAO – Understanding and Treating Corneal Scratches and Abrasions

The National Eye Health Education Program (NEHEP) – Low Vision Awareness
Maintaining Healthy Vision

Sandra Young, OD – GMO and the Nutritional Content of Food

S. Barry Eiden, OD, FAAO – Selecting Your Best Vision Correction Options

Suber S. Huang, MD, MBA – It’s All About ME – What to Know About Macular Edema

Jun Lin, MD, PhD and James Tsai, MD, MBA – The Optic Nerve And Its Visual Link To The Brain

Ronald N. Gaster, MD FACS – Do You Have a Pterygium?

Anthony B. Nesburn, MD, FACS – Three Generations of Saving Vision

Chantal Boisvert, OD, MD – Vision and Special Needs Children

Judith Delgado – Driving and Age-Related Macular Degeneration

David L. Kading OD, FAAO and Charissa Young – Itchy Eyes? It Must Be Allergy Season

Lauren Hauptman – Traveling With Low Or No Vision / Must Love Dogs, Traveling with Guide Dogs / Coping With Retinitis Pigmentosa

Kate Steit – Living Well With Low Vision Online Courses

Bezalel Schendowich, OD – What Are Scleral Contact Lenses?

In addition here are few other topics you might find of interest, including some infographics and delicious recipes.

Pupils Respond to More Than Light

Watery, Red, Itchy Eyes

10 Tips for Healthy Eyes (infographic)

The Need For Medical Research Funding

Protective Eyewear for Home, Garden & Sports

7 Spring Fruits and Vegetables (with some great recipes)

6 Ways Women Can Stop Vision Loss

6 Signs of Eye Disease (infographic)

Do I Need Vision Insurance?

How to Help a Blind or Visually Impaired Person with Mobility

Your Comprehensive Eye Exam (infographic)

Famous People with Vision Loss – Part I

Famous People with Vision Loss – Part II

Development of Eyeglasses Timeline (infographic)

What eye topics do you want to learn about? Please let us know in the comments section below.

7/21/15

Susan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

Your Comprehensive Eye Exam

Being able to see clearly is important to all of us. But it is also something we have a tendency to take for granted until we notice changes in our vision. The point of the yearly comprehensive exam is to monitor your eyes before any problems arise, and address any concerns that could affect your vision later. Here is what to expect at your next comprehensive eye exam.

An eye exam involves an external examination of your eyes followed by a series of tests designed to evaluate your vision and check for eye diseases. Each test evaluates a different aspect of your vision and includes specific tests for visual acuity, pupil function, muscle function, visual fields, eye pressure and viewing the back of the eye through a dilated pupil.

External Exam
The external examination consists of inspecting the eyelids, surrounding tissues and the eyeball including the sclera (white part of the eye), iris and cornea.

Visual Acuity & Fields
Visual acuity is your eye’s ability to detect fine details and see an in-focus image at a certain distance. A Snellen chart and a phoropter are used. The standard definition of normal visual acuity is 20/20. The term 20/20 comes from even sized objects that can be seen by a “person of normal vision” at the specified distance. For example, if a person can see at a distance of 20 feet an object that normally can be seen at 20 feet, then they have 20/20 vision. If they can see at 20 feet what a normal person can see at 40 feet, then they have 20/40 vision. For the visual acuity test each eye is tested separately to gauge your side or peripheral vision.

Pupil Function
An examination of the pupil begins with inspecting your pupils for equal size, regular shape, reaction to light, and direct and consensual reaction (meaning the pupil of one eye constricts when the other eye is exposed to light).

Eye Muscle Function
Eye movement is assessed two ways. First by having you move your eye quickly to a target at the far right, left, top and bottom. Then by slow tracking which uses the ‘follow my finger’ test, which tests all the muscles that move your eye.

Eye Pressure Measurement
Intraocular pressure, or IOP, is measured using a tonometer to determine the fluid pressure inside your eye. This test provides information regarding your potential for glaucoma.

Viewing the Back of the Eye
Increasing the size of your pupil with eye drops (known as dilating your eyes) allows the doctor to have a larger view of the back of your eye, including the retina, as demonstrated by this diagram. This is very important for diagnosis and tracking of macular degeneration and diabetic retinopathy.

Eye Structure
A special, high-powered microscope, called a slit-lamp, is used to view the structures of your eye clearly and in detail, enabling early diagnosis of a variety of eye conditions such as cataracts, presbyopia and corneal injury.

Taking care of your eyes, especially as you become older, is very important. Changes in vision may be gradual, or fast, but in both cases, early diagnosis is key to successful treatment and retaining your vision. It is suggested that individuals 40 and over have a comprehensive eye exam every one to two years. Exceptions would be if you have diabetes, in which case you should see your eye doctor yearly; or there is a family history of eye diseases such as glaucoma, macular degeneration, or corneal diseases, which may require more frequent visits to your eye doctor. If you have any degree of sudden vision loss, eye pain, or significant irritation, contact your eye doctor immediately.

4/23/15

Susan DeRemer, CFRE
Vice President of Development
Discovery Eye Foundation

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Retina

Top 10 Articles of 2015

Best’s Disease

Retinal Vascular Occlusions

Retinal arterial occlusions

Retinal venous occlusions

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Layers of the Retina

Research on mitochondrial DNA shows promise for treating AMD

Why You Need An Eye Exam

Questions To Ask After Your Eye Exam

Increased Awareness for Saving Vision

Retinal arterial occlusions

Retinal venous occlusions

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