Optimizing LASIK in the Over-40 Set

CHICAGO, April 19 -- When performing laser in situ keratomileusis (LASIK) surgery on patients 40 and older, less is more, according to a study here.

Slightly under-correcting the cornea in older patients appears to compensate for age-related differences in healing, said Dimitri T. Azar, M.D., of the University of Illinois here.

With this technique, 100% of patients in their 60s ended up with 20/30 vision or better, and 50% of these patients ended up with 20/20 vision or better, Dr. Azar and colleagues said online in the journal Ophthalmology.

As the safety and efficacy of laser in situ keratomileusis surgery have been established over time, more middle-age and older patients, who are generally not risk takers, feel comfortable giving it a try, Dr. Azar said. So the demand is increasing among the over-40 crowd.

However, previous studies have reported suboptimal results with advancing age, including poorer final visual acuity and higher rates of re-treatment, the study authors said.

The current study tested a laser in situ keratomileusis procedure that undercorrected the cornea by about 2% for every 10 years of age in order to compensate for the diminished healing response of those 40 and older. The retrospective study included 424 patients who underwent the procedure from 1999 to 2005. Of these, 215 (51%) were age 40 to 49, 175 (41%) were age 50 to 59, and 34 (8%), were age 60 to 69.

At about one year of follow-up, the proportion of myopic patients with 20/20 vision or better was 52% for those 40 to 49, 46% for those 50 to 59, and 50% for those 60 to 69. The proportion of these patients with 20/30 vision or better was 86% for those 40 to 49, 85% for those 50 to 59, and 100% for those 60 to 69. There were no significant statistical differences among the age groups.

The trend was similar among hyperopic patients. The proportion at one year who had 20/20 vision or better 24% for those 40 to 49, 40% for those 50 to 59, and 35% for those 60 to 69. The proportion with 20/30 vision or better was 84% for those 40 to 49, 80% for those 50 to 59, and 82% for those 60 to 69. Again, there were no significant statistical differences among the groups.

More patients in the oldest group tended to need retreatment. For example, about 20% of hyperopic patients 60 to 69 underwent retreatment, compared with 8.5% of those 40 to 49. The figures were similar for myopic patients. However, the differences were not statistically significant, the study authors said.

Although the study did not directly compare these results to those achieved in younger patients, they are similar, Dr Azar said. "You're not going to get the same sharp vision that you would have gotten in your 20s or 30s, but it comes close," Dr. Azar said.

The procedure appeared safe in the over-40 crowd. Overall, only nine eyes (1.3%) lost more than two lines of best spectacle-corrected visual acuity, and no eyes lost more than two lines, the study authors said.

Younger patients usually have a more aggressive healing response than older patients after laser in situ keratomileusis surgery. This healing response tends to try to change the eye back to its original shape, slightly undoing the effect of the procedure, Dr. Azar said. Older eyes likely don't need as much correction at the outset because their healing response is weaker, he speculated.

The study did not directly investigate the mechanism whereby under-correction produced these results in older patients, he added.

Other eye surgeons might want to keep the 2% undercorrection per decade technique in mind when performing LASIK, although the exact amount of undercorrection will depend on each individual surgeon's equipment and technique, Dr. Azar said.

The authors pointed out that "data from our series are limited by the retrospective nature of the study and the relatively heterogeneous sample." They also wrote that "the varying lengths of follow-up, the inclusion of patients operated on with different lasers and microkeratomes, and the difficulty in having clear inclusion and exclusion criteria add to the limitations of this study."

"LASIK for myopia and hyperopia has reasonable safety, efficacy, and predictability profiles in the presbyopic age group," the study authors concluded.

Laser in situ keratomileusis is not approved for patients under the age of 18. However, as long as one's eyes are in good health there is no upper age limit for the surgery, Dr. Azar said.