discovering dry eye
Review of Dry Eye Research
BY BARBARA CAFFERY, OD, MS, FAAO
Researchers are busily trying to solve the mysteries of the tear film and dry eye disease. Papers and posters on various aspects of the ocular surface were presented at the 2001 American Academy of Optometry meeting in Philadelphia.
Erickson presented research on the psychology of dry eye disease showing that patients who are extroverted score more positively on the McMonnies dry eye questionnaire and those who have a better sense of well-being score lower on the questionnaire. She suggests that psychological factors should be weighed in the scoring of these questionnaires.
Suber et al at the Southern College of Optometry monitored tear film break-up time and Schirmer tests before and after video game playing. After 60 minutes of continuous play, break-up time was reduced by up to 15 seconds. This may help to explain computer-related dry eye disease. Begley et al studied the blink and tear film thickness during tasks such as movie viewing that produce a normal blink rate, but a high number of incomplete blinks. This research suggests some dry eye is task-specific.
Korb et al presented a paper on how symptoms of contact lens discomfort correlate with the staining pattern of the upper lid's marginal conjunctiva. The staining pattern of this specific area, labeled "the lid wiper," shows a good correlation with the presence and severity of symptoms. The blink and the lid interaction with the lens becomes important in relieving symptoms.
Figure 1. Inserted silicone punctal
Charneski-Sikes and Bucci studied the use of silicone plugs (Figure 1) for treatment of dry eye symptoms by measuring tear lactoferrin post-LASIK, which they found to be reduced at day one. Silicone plugs inserted in the lower puncta of the eye improved lactoferrin concentration to a normal level for one month. They propose a feedback system in which the anesthesized cornea no longer stimulates the lacrimal gland, but the punctal plug promotes feedback. This contradicts research by Lowther et al who have noted epiphora in healthy patients fitted with silicone plugs who then stop having overflow tearing after two weeks, suggesting a negative feedback loop with the lacrimal gland. However, one study used post-surgical eyes, and the other used healthy eyes.
How to measure the tear film was also discussed. Researchers at the Texas Eye Research and Technology Center suggest that tear osmolarity and the new dry eye test that uses specific levels of flourescein to measure break up time correlate best with the diagnosing moderate dry eye disease. Simonin and Guillon proposed a new technique for measuring tear proteins using one µl of tear volume. This new electrophoresis method would offer a more practical way to establish tear protein profiles in dry eye disease.
Miller et al at the University of Houston reported that the presence of bulbar conjuctival folds did not correlate well with dry eye diagnosis. However, tear osmolarity, corneal staining and bulbar conjunctival injection did.
Tran et al reported differences in tear film characteristics in rigid vs soft lens wearers. The phenol red thread test showed reduced tear meniscus volume in soft lens wearers and higher tear osmolarity in rigid lens wearers. Lydon and Tighe showed that lipid deposition differed on the same lens type in different individuals.
Kornfield et al found a 50 percent satisfied to completely satisfied rating for their dry eye patients using moisture chamber spectacles.
Dr. Caffery has practiced optometry in Toronto, Canada, in a group setting dedicated to contact lens and tear film research since 1977.