Gender and hormone status affect LASIK outcomes

Hormone replacement therapy, birth control pills, even age – all influence excimer laser surgery outcomes. Still, females had good visual results.

DALLAS – Gender and hormone status influence laser refractive surgery outcomes regardless of the laser used, according to several studies discussed by Marguerite B. McDonald, MD, here at the annual meeting of the American Academy of Ophthalmology.

“The studies differ only with respect to the impact of hormone replacement therapy, birth control pills and pregnancy,” Dr. McDonald said. “Nevertheless, the females in all the studies still had excellent outcomes after PRK (photorefractive keratectomy) and LASIK.”

It has long been suspected that gender, as well as hormone replacement therapy and birth control pills, may impact clinical outcomes in excimer laser surgery, according to Dr. McDonald, a clinical professor of ophthalmology at Tulane University. “But there are very few papers in the peer-reviewed literature published on this subject, probably because most studies are sponsored by the (laser manufacturers), and the companies have very real marketing concerns. They wouldn’t want to find a difference and then have their laser labeled as the one that causes undercorrection or overcorrection in men or women,” she said.

Review of studies

The Melbourne Excimer Laser Group’s PRK study is one of the best to examine the issue of hormone status and excimer laser surgery, Dr. McDonald said. The study of 287 patients included 27 surgeons all using the same laser. When controlling for age and preoperative manifest refraction spherical equivalent, the mean number of correct logMAR letters that were read 1 year postop was significantly lower for postmenopausal women on hormone replacement therapy compared to the control group, Dr. McDonald reported.

“The authors thought that there was an interaction in menopause and hormone replacement therapy that could decrease effectiveness of PRK and photoastigmatic keratectomy (PARK),” she said. Best corrected visual acuity (BCVA) and clarity were not significantly different.

Dr. McDonald described another study of PARK in which a different laser was used and up to 6 D of myopia was treated. A review of uncorrected acuity 6 months postoperatively, including hormone users, indicated that “there were far greater numbers of men with really excellent uncorrected acuities, and this was significant at a P value of 0.003,” Dr. McDonald said.

Even if hormone users were excluded, the male/female difference was still statistically significant based on what percentage of each group was at least 20/20 uncorrected, she said. There were no significant differences in regard to 20/20 uncorrected outcome, whether or not the women were on hormone replacement therapy, birth control pills or no pills at all. There were no significant male/female differences with regard to 20/40 uncorrected best corrected vision loss, ±0.5 D of intended outcome, ±1 D of intended outcome, BCVA of 20/20 or BCVA of 20/25.

Dr. McDonald also discussed a study of myopic LASIK up to 10 D.

“Looking at uncorrected acuity 6 months postoperatively, we saw that males with a median age of 43 were more likely to have an uncorrected acuity of 20/20 than females over age 43, with a 75% versus 28% distribution,” Dr. McDonald said. “So older men did better than older women.” There was no significant association in this study with respect to the presence or absence of hormone replacement therapy in older females.

In the same study, it was determined that females who wore hard contact lenses preoperatively were more likely to be within ±0.5 D of target than male contact lens wearers. “This was very statistically significant at 92% versus 50%,” Dr. McDonald said. Females on birth control pills were less likely to be within ±0.5 D than females not using birth control pills, with a 65% versus 77% distribution.

The only variable

In this same study, analysis of patients with undercorrection of more than 1 D indicated that the only significant variable, out of 17 variables treated, was gender. Although 11 of the 12 subjects with an undercorrection in their manifest refraction of greater than 1 D were female, 93% of the females were not undercorrected in manifest refraction spherical equivalent, versus 99% for the men, and 94% of the females were not undercorrected in the manifest spherical component versus 99% for males.

Outcomes of a study looking at hyperopic LASIK differed somewhat. Uncorrected acuity at 6 months postoperatively indicated that males with 20/20 visual acuity were 5.5 years younger on average than the median age of 53, while the females were 3 years younger on average, representing a statistically significant difference. The use of hormone replacement therapy reduced the chance of achieving 20/20 in females. There was a 26% chance of 20/20 for females on hormone replacement therapy versus 45% without hormone replacement therapy. Longer procedure time, in this study, was associated with decreased accuracy for females but not males. This may have been influenced, the authors thought, by the amount of attempted correction and interruptions for limbal bleeding, Dr. McDonald reported.

For Your Information:

• Marguerite B. McDonald, MD, can be reached at 2626 Napoleon Ave., New Orleans, LA 70115-6307; (504) 896-1250; fax: (504) 896-1251. Dr. McDonald has no direct financial interest in the products mentioned in this article, nor is she a paid consultant for any companies mentioned.

Reference:

• The Melbourne Excimer Laser Group. The relation of hormone and menopausal status to outcomes following excimer laser PRK in women. The Australia and New Zealand Journal of Ophthalmology. 1996.