We read with interest the important article by Vera and associates reporting that temporally placed laser peripheral iridotomies are less likely to cause linear dysphotopsia compared to ones placed superiorly.
We agree with the authors that while patients can experience a variety of visual symptoms including haloes, shadows, and crescents following laser peripheral iridotomy, linear dysphotopsia seems to be the most specific symptom pertaining to laser peripheral iridotomies, and certainly the most problematic. We suspect that the magnitude of this problem may actually be underreported, as patients are not often asked specifically about visual symptoms that developed after laser peripheral iridotomy is performed. From our own experience, the number of patients reporting linear dysphotopsia has risen over the years.
We applaud the authors’ efforts in conducting a prospective, randomized, and masked study directly comparing temporal and superior laser peripheral iridotomy position and the prevalence of linear dysphotopsia.
Differing opinions regarding the role of lid position in causing visual symptoms following laser peripheral iridotomy have previously been expressed. While Congdon and associates, in their recent paper, reported that stray light and prevalence of visual symptoms did not differ between subjects regardless of lid coverage, Spaeth and associates have suggested that visual symptoms are more likely in patients with partially or fully exposed laser peripheral iridotomies.
Current clinical guidelines in our hospital state that laser peripheral iridotomies should be placed as close to the 12 o’clock meridian, as peripherally as possible in order to ensure that the iridotomies are entirely covered by the upper lids. Following this randomized controlled trial, we are now considering a change in clinical practice to have all laser peripheral iridotomies placed as temporally as possible.
While laser peripheral iridotomy is a routinely common procedure for ophthalmologists, we feel that little thought is currently given to the potentially debilitating effects that linear dysphotopsia might have on previously asymptomatic patients undergoing this prophylactic procedure. If linear dysphotopsia rates are as high as the 10.7% mentioned in Dr Vera’s study, patients need to be carefully counseled before undergoing prophylactic laser peripheral iridotomy.