Dry eye a constantly changing landscape

Washington, DC-Dry eye disease affects millions of people worldwide and with that has come a recent greater awareness among patients that it is indeed a problem. As the recognition of the magnitude of dry eye is changing, so too has knowledge of its pathogenesis, the technology facilitating diagnosis, and the drugs that are becoming available to treat it. General ophthalmologists will be increasingly challenged to learn more about the disease and the best ways to treat individual patients, according to Michael Lemp, MD.

"Patients have recognized over the years that they have had a problem but have not been able to articulate it well to physicians. In terms of the extent of the problem in society in general, we have become much more aware of dry eye in recent years. Practicing physicians can document dry eye as a frequent complaint among patients," said Dr. Lemp, clinical professor of ophthalmology, Georgetown University and George Washington University, Washington, DC. "In addition, the American Academy of Ophthalmology recently reported that 30% of patients complain of ocular irritation to ophthalmologists. This represents a substantial percentage of patients in office practices."

The unmet need

With increasing recognition of dry eye, Dr. Lemp also explained that there will be a significant impact on how ophthalmologists and optometrists practice, because until now only about 5% of those with symptoms have had dry eye diagnosed.

"It is going to be an increasing challenge for doctors to diagnose dry eye," he said. "Most standard tests used in the office are not positive except for patients with moderate to severe symptoms. Patients with mild to moderate disease do not test as abnormal, which results in the physicians making an educated guess as to the cause of the symptoms in the absence of findings."

Hand in hand with this is the attitude among ophthalmologists that dry eye is not a disease, according to Dr. Lemp, but rather a concomitant of aging and an inconvenience for patients. Consequently, general ophthalmologists have not addressed dry eye as a condition that can worsen because of the specific pathogenetic mechanisms that are operative and can result in tissue destruction.

"Many doctors have felt constrained because they believe there has been a lack of effective treatments and only artificial tears were available to ease symptoms," he said.

Patient complaints

The results of Schirmer testing and staining of the ocular surface often do not reflect the patient complaints of dry eye symptoms.

"There is increasing evidence that no matter what the initiating systemic causes or associations with the beginnings of dry eye, when tear film/ocular surface abnormalities begin and there is discomfort, several global features of dry eye occur, namely, tear film instability, which results in more rapid breakdown between blinks, and elevated tear film osmolarity. These factors probably occur before there is a consistent decrease in tear production and before breakdown of the ocular surface," Dr. Lemp explained.

Many patients do not have progress beyond that stage to consistently decreased tearing and breakdown of the ocular surface; nevertheless they have symptoms.

Of great interest to Dr. Lemp are the visual changes that occur in patients with dry eye. On testing of typical patients, the visual acuity is 20/20. With rapid breakdown of the tear film between blinks, the image on the retina becomes distorted; patients respond by blinking more often to re-form the tear film. With chronic increased blinking comes ocular fatigue, one of the most common symptoms of dry eye, he explained.