discovering dry eye
Morning Dry Eye and Extended Wear Contact Lenses
BY CAROLYN BEGLEY, OD, MS, SOPHOCLES
SOPHOCLEOUS, ERIKA DUGGAN
Many extended wear patients complain of dry, scratchy eyes and poor vision upon awakening. Usually these symptoms disappear within 15 to 30 minutes, but some some patients report tinued discomfort over the course of the day. These early-morning symptoms may be irritating enough to cause patients to reject overnight wear of contact lenses.
continued discomfort during the day. These early-morning symptoms may be irritating enough to cause patients to reject overnight wear of contact lenses.
We investigated these symptoms in a recent study conducted at the Indiana University School Optometry. Subjects were fit with Vistakon Acuvue lenses and instructed to wear the lenses over-night. In the morning, subjects were transported to the clinic with one eye taped shut. Measurements of tear quality, vision and symptoms were made over the next two hours.
Figure 1. Photos of tear film after eye opening, 15 minutes and one hour
Tear quality over the lenses was measured by retroilluminating the tear film. To use this technique, the slit lamp beam is rotated close to the "on axis" position until you obtain a red reflex. Focus the optics of the slit lamp on the tear film. Any disturbance or variation in the normal thickness of the tear film appears as a shadowed, topographic-like image within the pupil. Figure 1a shows the tear film of one subject just after eye opening. The uneven surface in the retroilluminated image is due to tear film disruption on the lens surface. Figure 1b was taken about 15 minutes later, when the lens was sticking to the upper lid with blinking and was pulled superiorly. The dark arc across the pupil is the edge of the decentered lens. Figure 1c shows the same patient approximately one hour later. By then, the tear film was evenly spread over the surface of the lens, the lens was no longer sticky, and it was centered and fitting well.
We also measured vision and symptoms. The same patient pictured in Figure 1 had 20/30 vision just after eye opening, but vision had improved to 20/15 a half an hour later. Her initial poor vision was caused by the uneven tear film in Figure 1a. Her vision also fluctuated as the lens decentered. The eye's aberrations were measured using the COAS (Complete Ophthalmic Analysis System) wavefront sensor, which confirmed initially high ocular aberrations after eye opening. These decreased markedly within the first half hour Initial symptoms included eye discomfort, dryness, soreness, foreign body sensation, disturbed vision and itching, but most disappeared within the first hour of wear.
The extended wear patient in Figure 1 was typical of those who complained of dry, irritated eyes upon eye opening. Other patients, who reported few symptoms, had relatively "clean" lenses and good vision upon eye opening after overnight wear. It is evident from the Figure 1 images that the morning dry eye complaints of some extended wear patients are due to an uneven, "sticky" tear film on the lens surface. This appears to be related to overnight lens wear because when the experiment was repeated without lenses, the tear film was uniform upon eye opening.
Dr. Begley is an associate professor at the Indiana University School of Optometry and is also a member of the Graduate Faculty. Mr. Sophocleous and Ms. Duggan are second-year optometry students at IU.