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Posterior pole conditions range from the elusive to the obvious

Issue: August 2003

ByJennifer Byrne

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Diagnosing and treating uncommon ocular conditions and complications is one of the more challenging aspects of the optometric profession. Although such anomalies may not be encountered frequently, it is nevertheless important for the practitioner to be skilled in their diagnosis and treatment.

In this article, practitioners tell Primary Care Optometry News of their experiences with peripheral retinal acute zonal outer occult retinopathy (AZOOR) and scleral buckle migration.

AZOOR: an elusive diagnosis

AZOOR is a condition in which retinal dysfunction occurs in response to multifocal inflammation at the back of the eye.

According to Mark T. Dunbar, OD, FAAO, AZOOR is a relatively rare disease and is difficult to diagnose. “Unfortunately, because it is such a rare disease and not really well known, it is often misdiagnosed or overlooked completely,” he said.

Dr. Dunbar said J. Donald Gass, MD, of Vanderbilt University in Nashville, Tenn., made a definitive description of the disease in 1994 while he was at Bascom Palmer. “Originally, he had described 13 patients who were young women and had complained of rapid loss of peripheral vision,” he said. “One of the chief complaints they described was photopsia, or seeing ‘sparkling lights.’”

AZOOR can be particularly confounding, Dr. Dunbar said, because patients with this condition may present with normal visual acuity, normal fluorescein angiography and a normal fundus examination despite severe loss of visual field.

“From a clinical perspective, you may not see anything wrong,” he said. “That is what really makes the disease very difficult to diagnose. Most of these patients have vague non-specific symptoms that can really be almost anything.”

Dr. Dunbar said the diagnostic workup includes an electroretinogram (ERG) and automated perimetry (visual fields), coupled with an index of suspicion.

“Usually these people come to see you after having had a huge neurologic workup that proves to be normal,” he said. “They have seen neurologists, and some are even described as being malingerers, because you really can’t find anything.”

Dr. Dunbar said these patients usually have some degree of vitritis and, later on in the disease, some attenuation of the vessels.

“The characteristic changes are peripheral field defects that are pretty much unassociated with any changes in the fundus or fluorescein angiogram,” Dr. Dunbar said. “There are no particular fundus changes to distinguish it from anything else. That is what makes it difficult to diagnose.”

No known treatment

Dr. Dunbar added that there can be some degree of confusion between AZOOR and certain other unusual conditions, including multiple evanescent white dot syndrome (MEWDS) and another inflammatory condition called pseudo-presumed ocular histoplasmosis (pseudo-POHS) or multifocal choroiditis. It can also mimic retinitis pigmentosa and non-specific neurological disease, he said.

There is currently no known treatment for AZOOR, Dr. Dunbar said. “It is thought to be inflammatory, so I am sure steroids have been considered, but there haven’t been enough cases to know if it really works,” he said.

Practitioners should be very careful in recognizing this easily overlooked disease, Dr. Dunbar said. “It is a very difficult diagnosis to make due to the subtle nature of the disease and the fact that it can present with a near-normal eye exam,” he said. “Index of suspicion should be aroused for patients, especially women, who have this characteristic photopsia. And diagnoses should be made based on ERG and visual field loss.”

Scleral buckle migration in RD patients

Another unusual phenomenon is the migration and need for removal of scleral buckles used to treat retinal detachments.

“The last time I had to remove one was 3 or 4 years ago,” said Bert M. Glaser, MD, a retinal specialist who practices in Chevy Chase, Md. “It is very obscure.”

Dr. Glaser explained that, if a scleral buckle migrates, the conjunctiva breaks down and is also exposed. “The only thing to do is just remove it,” he said. “You can usually remove it during a very short outpatient procedure.”

David M. Krumholz, OD, FAAO, of the Department of Clinical Sciences at the State University of New York College of Optometry, said he recently saw a retinal detachment patient whose scleral buckle was causing complications. “She was having some chronic irritation in the eye, and the scleral buckle was eroding through the conjunctiva,” he said. “We figured we had another 3 months before it would erode through. We decided that it would have to be removed.”

When to remove?

Dr. Krumholz explained that a scleral buckle is a piece of silicone sponge sewn on the outside of the eye to correct a retinal detachment. The scleral buckle indents the sclera into the retina so that they are touching, and it heals in this way. The scleral buckle is usually then left in place to avoid the need for another surgery, Dr. Krumholz said.

“But because you’ve got this hunk of plastic sitting there and it is only covered by the thin conjunctiva, sometimes the conjunctiva can be pulled very thin over it,” he said. “The buckle can actually erode through the conjunctiva.”

He said it is fairly easy to recognize when a scleral buckle needs to be removed. “You can see it from the outside of the eye without a microscope. You just have to pull the lids up and have the patients look around,” he said. “You see this big red mound, which is basically the inflammation overlying the buckle. It is fairly noticeable.”

Dr. Krumholz described scleral buckle removal as a fairly simple procedure, adding that an operating room is used only due to the need for sterile conditions.

“A small incision is made into the conjunctiva, it is spread apart and opened a little bit, and the sutures that held the scleral buckle in place are just snipped. Then, you lift it out,” he said. “You pull the sutures out, and then you put sutures in the conjunctiva to hold it closed.”

Dr. Krumholz said deciding when to remove a scleral buckle is not difficult. Looking at the condition of the eye is usually sufficient.

“Once it is inflamed and starts irritating the eye, it is a portal for infection,” he said. “The benefits of removing it then outweigh the risks.”

For Your Information:

• Mark T. Dunbar, OD, FAAO, practices at the Bascom Palmer Eye Institute. He can be reached at 900 NW 17th Street, Miami, FL 33136; (800) 329-7000 ext. 4042; fax: (305) 326-6113; e-mail: mdunbar@med.miami.edu.
• Bert M. Glaser, MD, is a member of the Primary Care Optometry News Editorial Board who practices in Chevy Chase, Md. He can be reached at 5530 Wisconsin Ave., Chevy Chase, MD 20815-4401; (301) 986-8747; fax: (301) 986-8944.
• David M. Krumholz, OD, FAAO, teaches at SUNY College of Optometry. He can be reached at 33 West 42nd Street, Rm. 923, New York, NY 10036; (212) 780-4982; fax: (212) 780-4980; e-mail: dkrumholz@sunyopt.edu.