February 2009

 

OPHTHALMOLOGY NEWS

 

Dry eye in diabetics


by Vanessa Caceres EyeWorld Contributing Editor

   

Diagnosis and treatment pearls to help these patients

Tear duct plugs Tear duct plugs or cauterization can be considered in patients with inadequate tear flow as measured by the Schirmer test, to help keep the ocular surface more moist

Meibomian gland dysfunction

Meibomian gland dysfunction leads to an evaporative type of dry-eye syndrome; patients complain of pain, discomfort, and burning; symptoms are usually out of proportion with the signs Source: Esen K. Akpek, M.D.

Are your diabetic patients regularly screened for dry eye? If they’re not, they should be, say a number of ophthalmologists who treat diabetic dry-eye patients.

“Most internists send diabetic patients to a retinal specialist once or twice a year to look at the back of the eye, but you never hear about a check by a corneal specialist,” said Robert Latkany, M.D., founder and director, Dry Eye Clinic, New York Eye and Ear Infirmary, New York. Although the retinal exam that screens for diabetic retinopathy is crucial, regular corneal exams are also important for diabetics, Dr. Latkany said.

Here’s why: Roughly half of diabetic patients have dry eye, as reported by a number of studies. However, these same patients often do not feel their symptoms. “Some of the worst dry-eye patients don’t complain,” Dr. Latkany said. “They have a compromised epithelium, which can lead to infections. They have to be watched closely.”

Esen K. Akpek, M.D., director, Ocular Surface Diseases and Dry Eye Clinic, Wilmer Eye Institute, Johns Hopkins University, Baltimore, likens it to the common problems diabetics have with sores or blisters that they do not feel on other parts of their body. This lack of sensation also occurs in the eye in the form of neurotrophic keratitis.

It’s not entirely clear why diabetic patients are more prone to dry eye. “Although the mechanism generating diabetic ocular surface abnormalities is unclear, the effects of aldose reductase, multiple peripheral nervous lesions, decreased corneal sensitivity, and the reduction of stimulatory signals from the ocular surface to the lacrimal gland may be involved,” said Ling Yu, M.D., department of ophthalmology, West China Hospital, Sichuan University, Chengdu, China. Dr. Yu co-authored a study published online in June 2008 in Ophthalmologica that found worse tear function in patients with proliferative diabetic retinopathy compared with those who had nonproliferative diabetic retinopathy.

Another study, published online in June 2008 in BMC Ophthalmology, found a 54.3% prevalence of dry eye in 199 type 2 diabetic patients.

“Diabetic retinopathy and dry eye appear to have a common association. Further studies need to be undertaken to establish an etiologic relationship. However, examination for dry eyes should be an integral part of the assessment of diabetic dry-eye disease,” wrote the study investigators, led by Masoud Reza Manaviat, M.D., Yazd Diabetes Research Center, Yazd, Iran.

Here are some recommendations on how to diagnose and treat dry eye in diabetic patients.

Diagnosis details

For the most part, diabetic patients can undergo normal dry-eye diagnostic tests, such as tear break-up time, Schirmer testing, and rose Bengal staining. However, two other tests that may not be as common are also helpful in these patients.

“Some studies demonstrated that there are marked alterations in the diabetic tear protein patterns,” Dr. Yu said. “This was also found in our investigation. The changes in the tear protein patterns of the diabetic patients may be used as a new non-invasive diagnostic tool.”

Another underused test is an esthesiometer, Dr. Latkany said. This test measures corneal sensitivity but is probably not found in many ophthalmologists’ exam rooms, he said. To reproduce a similar effect, Dr. Latkany will have patients look straight ahead while he twirls two or three strings from a cotton-tip applicator (Q-tip) against the cornea. “A patient should feel it right away,” he said. If he doesn’t, you know that his sensitivity is diminished. A similar test can be used in suspect herpes patients because they will also have decreased sensitivity, Dr. Latkany said.

It’s important to conduct the sensitivity test before fluorescein dye is used in the eye, which would decrease sensation.

Clinically, it’s easy to recognize diabetic patients with dry eye because they have erosions that are not specific to any one part of the eye, Dr. Latkany said. These patients may also have a non-healing corneal ulcer or vision that gets no better than 20/30 or 20/50, Dr. Akpek said. These problems often develop after surgery or some sort of trauma, and at that point the patient is referred to a corneal specialist.

“Anything that tips the balance can put these patients in a terrible condition,” Dr. Akpek said. Other-wise, “they’re pretty asymptomatic.”

This is why it’s key to clinically explore the eye and not just rely on patient complaints, which may be minimal or non-existent in these patients. In the recently published study from Dr. Manaviat, of the 108 patients with dry eye, 36.2% felt a gritty sensation and 19.1% had soreness, but none of them complained of pain and tearing.

The longer a patient has diabetes, the more likely it is that he or she will have dry eye or have a severe form of it, physicians said. For example, the study from Dr. Manaviat found that dry-eye patients had diabetes for a mean of 11.48 years compared with 9 years in patients who did not have dry eye. Although dry eye was more common in older, female patients in their study, this association was not significant.

Treatment pearls

Treatment of dry eye in diabetics should not be all that different compared with typical dry-eye patients, but you may want to err on the aggressive side, Dr. Latkany said.

“This isn’t going to get significantly better with age, so I don’t hesitate to be more aggressive,” he said. “They can’t sense that there’s trouble.”

Dr. Akpek often begins treatments with steroids, Restasis (cyclosporine ophthalmic emulsion, Allergan, Irvine, Calif.), or both. The anti-inflammatories often do not bring back tear function to normal but at least provide some relief, she believes.

She also tends to use punctal plugs more often in these patients as a long-term solution. “A significant proportion of the tear function doesn’t come back,” she said.

Prevention could also help a smaller proportion of these patients experience a severe form of dry eye, Dr. Akpek said. “With all patients undergoing eye surgery, they should address ocular surface problems prior to surgery,” she said. Internists should also step up their role in encouraging regular corneal exams. “I don’t think the physicians are referring them to ophthalmologists for dry eye,” Dr. Akpek said.

Editors’ note: Drs. Latkany, Akpek, and Yu have no financial interests related to their comments.

Contact information

Akpek: 410-955-4594, esakpek@jhmi.edu
Latkany: 212-832-2020, relief@dryeyedoctor.com
Yu: yuling_xiehanping@hotmail.com

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