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 disease
Friedrich Best

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.

Best's disease
Best’s disease
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

Dr. Esmaili posterior vitreous detachmentDaniel D. Esmaili, MD
Retina Vitreous Associates Medical Group

Posterior Vitreous Detachment

10/30/14

Have you ever noticed floaters in your vision? Perhaps they looked like a bunch of small dots or maybe a cobweb swaying back and forth in your visual field. Were the floaters associated with flashing lights that made you think there was a lightning storm coming your way? These are typical symptoms of a posterior vitreous detachment (PVD), and if you have had these symptoms you are far from alone.
Floaters Posterior vitreous detachment
PVD is a natural process that occurs in the majority of people usually over the age of 50. The vitreous is a jelly-like substance that occupies the back portion of the eye. The vitreous is comprised primarily of water, which accounts for 99% of its volume, and the remaining 1% includes proteinaceous substances such as collagen fibers as well as hyaluronic and ascorbic acids. The collagen fibers act as a scaffold to allow the vitreous to maintain a formed shape as well as provide a means for the vitreous to attach to the retina, which is the light-sensitive tissue that lines the inner back wall of the eye and is critical for vision. As we age, changes in these fibers cause the vitreous to lose its shape and eventually pull away from the retina. When the vitreous separates from the retina, this is called a PVD.

As we age, the collagen components of the vitreous can clump together and are free to float in the eye. When the vitreous separates from the retina during the development of a PVD, the floaters may become more noticeable or numerous. It is common for patients to describe floaters of different shapes and sizes, and patients may notice just one or in some cases many. In many people, a PVD develops slowly and there may be no symptoms or just a few annoying floaters. In others, a PVD may occur abruptly and cause more dramatic symptoms that can be very anxiety provoking.

Since the normal process of PVD development involves the vitreous tugging on the retina until it can fully separate, this tugging can result in flashing lights that can commonly appear in the peripheral, or side, vision. These flashing lights are sometimes described as lightning streaks, and patients may notice them more readily in settings with low ambient light. The flashes of light typically resolve once the vitreous has fully separated from the retina and the tugging has ceased.

The good news is that PVD is usually harmless in the vast majority of cases, and the annoying floaters will become less bothersome over time. In approximately 5-10% of cases, the vitreous can tug too hard on the retina as it tries to separate and it may pull a hole or tear in the retina. Tears in the retina can predispose to retinal detachment, which is a serious condition that can lead to permanent vision loss.
It is important to recognize that the typical symptoms of a regular PVD are often similar to a PVD with an associated tear. For this reason, it is recommended that all patients with the new onset of floaters or flashes have a dilated eye exam. If a retinal tear or detachment is discovered, early treatment can help prevent loss of vision.

Treatment for PVD usually involves simple observation. With time, the flashes will go away, and the floaters will become less noticeable. More recently, few providers have claimed that floaters can be treated with a laser in order to make them less noticeable. I would caution that this is not mainstream therapy at the current time, and I do not advise my patients to pursue this option. Another treatment possibility is vitrectomy surgery, where the vitreous gel is removed as part of a surgical procedure. Due to safety advances in vitrectomy surgery, this is now a potential option for the rare patient who has floaters that are so numerous and bothersome that they are negatively impacting their activities of daily living. For the vast majority of patients this is not necessary.

When I see a patient with a PVD, I often recommend one follow-up visit in 4-6 weeks to make sure there are no retinal holes or tears that have developed in the interim. If the other eye has not had a PVD yet, I will counsel them that a PVD will most likely develop in that eye within the next few years, and when it does they need to be examined. I will also discuss the retinal detachment warning signs. Patients with retinal detachment will not only have symptoms similar to PVD, including flashes and floaters, but in addition they may also notice what looks like a black shade or curtain that starts in the peripheral vision and extends towards the central vision. My patients are taught that this symptom requires an immediate examination.

In conclusion, PVD is a natural process that the majority of people will experience in their lives. The symptoms can range from having no symptoms at all to many floaters with associated lightning flashes. In the majority of patients, there is no damage to the eye or threat to the vision. A dilated exam is recommended to look for possible holes or tears in the retina, and if these are uncovered, prompt treatment can prevent vision loss.

Dr. Esmaili posterior vitreous detachmentDaniel D. Esmaili, MD
Retina Vitreous Associates Medical Group