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Treatment of contact lens-related dry eye is based on disease severity and frequently results in discontinuation of contact lens use.
"Contact lens wear is a significant risk factor for dry eye," said Dr. Donnenfeld, who is co-director, external disease, Manhattan Eye, Ear & Throat Hospital and founding partner, Ophthalmic Consultants of Long Island, Rockville Centre, NY. He added that although many steps can be taken to treat contact lens-related dry eye, anti-inflammatory therapy may be necessary to provide good symptomatic improvement.
Discussing the extent of dry eye associated with contact lenses, Dr. Donnenfeld cited a 2005 study by Nichols et al., evaluating dry eye symptoms by refractive modality. The authors found that 52.3% of contact lens wearers had dry eye, compared with 23.9% of patients with glasses and 7.1% of patients with no correction.
"Why is that a problem? What a contact lens does is block the exchange of oxygen and carbon dioxide, producing hypoxia and acidosis, which damages the corneal nerves," he continued. "The damage to the corneal nerves decreases the afferent information going to the brain stem. There's less information in the brain stem, [and] the brain stem is less stimulated to send impulses to the lacrimal glands to produce more tears. This creates a cycle of dry eye with further tissue damage and more dry eye symptoms."
Dr. Donnenfeld explored the diagnostic and treatment options for contact lens-related dry eye through a case study of a 48-year-old woman who initially presented to request punctal plug replacement. She had a several-year history of dry eye with symptoms such as dry, gritty eyes; her medical history was negative.
She wore bifocal contact lenses 18 or more hours a day and was unwilling to modify her wear time. Her therapy at the time of presentation included punctual plugs, 1 g/day of flaxseed oil, and unpreserved artificial tears six times an hour. Such extensive use of artificial tears is in itself a sign of moderate to severe dry eye, Dr. Donnenfeld said.
Several tests could be administered to diagnose this patient's condition. A general assessment of symptoms and history would be the starting point; following that, conjunctival staining with lissamine green or rose bengal is one of the most important tests, Dr. Donnenfeld said. Others that may be used include Schirmer testing, cotton thread, tear break-up time, tear film assessment, videokeratoscopy, and corneal staining with fluorescein.
For this patient, Dr. Donnenfeld said he used tear break-up time, tear film assessment, and fluorescein and lissamine green staining as diagnostic tests. His physical examination revealed bilateral grade 1 conjunctival injection, red lid margins, and slightly viscous meibomian gland secretions.
"There was not only decreased tear film but there was orbital and lid disease as well," Dr. Donnenfeld said. "That's a very important point in that, very commonly, dry eye is a combination of not only aqueous production but also meibomian gland secretion, and it's the two aspects of tear film that are damaged in significant cases."
Results of diagnostic tests confirmed the severity of the patient's dry eye. The tear break-up time was 1 second, and there was grade 1 inferior corneal staining and grade 2 conjunctival staining in both eyes.