Corneal shield improves vision after PRK, LASIK

New York-The immediate postoperative period after PRK and LASIK can be difficult for patients because of refractive variations, surface irregularities, and poor optical clarity. However, a novel eye shield (Nexis Vision Corneal Shield, Nexis Vision) appears to help patients who have undergone PRK and LASIK by providing rapid visual and functional recovery.

Marguerite B. McDonald, MD, demonstrated the changes in refractive error that occurs with epithelial migration after PRK. With bending of the bandage lens conforming to the migrating epithelial edge, a hyperopic shift occurs first that is closely followed by a myopic shift that occurs with epithelium building over the visual axis to 30% thicker than preoperatively.

“There is a wild swing in refraction during the first postoperative week,” said Dr. McDonald, clinical professor of ophthalmology, New York University Langone Medical Center, New York.

In a contralateral two-site study, 25 patients (14 men, 11 women) received the shield in one eye and a bandage contact lens (AcuVue Oasys, Johnson & Johnson Vision Care) in the fellow eye. The results with the two products were compared to determine the effects on visual recovery and healing rates after PRK.

“There was a huge difference in the postoperative uncorrected visual acuity (UCVA) between the two products in favor of the shield at all postoperative time points from 1 hour through days 1 to 7,” she said.

The vision with the shield was an average of 20/25 during first postoperative week with the exception of day 4 when it was 20/32. With the bandage contact lens, the visual acuity was about 20/40 at 1 hour and improved to about 20/32 at the end of the first postoperative week. The differences in vision were significant (p < 0.05) between the two products except at day 4, Dr. McDonald noted.

A significant (p < 0.05) difference also was seen on days 3 and 4 postoperatively in the speed of epithelial healed in favor of the eye shield.

“On day 3, 52% of the eyes with the Nexis shield were completely healed compared with 32% with the Oasys bandage lens; on day 4, the respective percentages were 92% and 72%,” she said.

For LASIK patients, the eye shield also increases the speed of the visual recovery. The results from four trials of the eye shield were very similar to those after PRK (i.e., the UCVA was significantly (p < 0.05) better in the eyes with an eye shield immediately postoperatively and at ½, 1, and 2 hours postoperatively). The eye shield also provided patients with rapid functional recovery compared with conventional LASIK.

“[This corneal shield] appears to help patients after PRK and LASIK with the speed of visual recovery and functional recovery,” Dr. McDonald concluded. She expressed hope that this product would become available in 2013.

This article was adapted from Dr. McDonald’s presentation during Refractive Surgery 2012 at the annual meeting of the American Academy of Ophthalmology.

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