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Brimonidine Helps Soldiers With Poor Night Vision Following Refractive Eye Surgery: Presented at ARVO

By Earl R. Nichols

FT. LAUDERDALE, F.L. -- May 8, 2006 -- A study done for the United States Army has found that soldiers who have had visual problems following refractive eye surgery and have treated their eyes with brimonidine ophthalmic solution 0.15% (Alphagan-P), experience significant improvements in night vision and contrast sensitivity.

Contrast sensitivity following refractive surgery (usually Laser Assisted in situ Keratomileusis) occurs when the area of the cornea that is ablated overlaps with the pupil, which dilates in low lighting conditions.

Brimonidine has previously been shown to prevent the pupil from dilating in some patients, according to researcher (Major) Richard D. Stutzman, MD, ophthalmologist, Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, DC.

The study, presented here on May 2^nd at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting, evaluated 6 soldiers who had undergone eye surgery and were experiencing significant complaints with their contrast sensitivity and night vision.

Possible reasons for the loss of sensitivity including dry eye, residual refractive error, ocular surface abnormalities, flap irregularities, interface opacities, and postoperative haze were ruled out.

The degree of contrast sensitivity and loss of night vision were all tested 1 hour before and 1 hour after patients instilled brimonidine in their eyes. They also used brimonidine every night for 1 month and had the tests repeated.

Significant improvements in low contrast visual acuity and in small letter contrast sensitivity were seen as little as 1 hour posttreatment. At the end of 1 month, all of the soldiers reported subjective improvements in night vision. Improvements were also seen in mesopic low contrast visual acuity at 1.25%, 2.5%, and 5%. (Mesopic lighting refers to normal room lighting and mesopic low contrast visual acuity refers to the degree of contrast between the letter and the background.)

A 100% contrast is pure black on chalk white, while a difference of 1.25% would almost be considered white-on-white.

"Because many soldiers are required to perform duties in reduced light or dark night settings, night vision disturbances have the potential to jeopardize operational task performance. Soldiers experiencing postoperative glare, haze, and starbursts could be significantly impaired in their ability to perform night time duties, thereby reducing the ability to function according to their military duties. In a worst case scenario, difficulty seeing at night after surgery may lead to increased risk of injury or even death. The ability to treat postoperative visual aberrations may have significant implications on military readiness," the authors wrote in their poster.


[Presentation title: Alphagan-P Improves Night Vision Difficulty and Contrast Testing After Refractive Surgery. Poster 3462 B995]

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