New Visual Disturbances by Site of Laser Peripheral Iridotomy
Ophthalmology, March 2018
In a multicenter study, Srinivasan et al. aimed to determine whether the site of laser peripheral iridotomy (LPI) has any bearing on the emergence of postoperative visual symptoms. They found that the incidence of new visual dysphotopsias is similar for the superior and nasal/temporal locations.
For this prospective randomized, single-masked trial, the authors included 559 South Indian adults who were primary angle-closure suspects (PACS) or had a diagnosis of primary angle closure (PAC) or primary angle-closure glaucoma (PACG) in both eyes. Participants were assigned randomly to receive bilateral superior LPI (n = 285) or bi-lateral nasal/temporal LPI (n = 274) and were matched for age, gender, and PACS/PAC/PACG distribution. The main outcome measure was occurrence of new-onset dysphotopsia symptoms. Visual disturbances were assessed pre-operatively and 2 weeks post-LPI, utilizing a survey based on the 7-symptom dysphotopsia questionnaire used by Spaeth et al. in 2005.
Laser energy settings were similar for both LPI groups, but superior LPI involved more shots and greater total energy. There were no significant between-group differences in postoperative anterior chamber reaction or LPI area. The proportion of patients with at least 1 symptom before LPI was similar (superior, 15.8%; nasal/temporal, 13.9%), as was the incidence of each symptom.
After LPI, 8.9% of the study population reported 1 or more new symptoms; the most common were linear dysphotopsias (2.7%), glare (4.3%), and blurring (4.3%). Patients who underwent superior LPI did not report more new-onset dysphotopsia symptoms than those who had nasal/temporal LPI (8.4% vs. 9.5%), and the incidence of any new individual symptom was comparable. None of the following influenced the odds of new dysphotopsia symptoms postoperatively: location of LPI, size of LPI area, or quantity of laser energy.
Although dysphotopsia symptoms emerged after LPI in a large portion of the study population, the overall frequency of dysphotopsias did not increase. LPI site selection should be based on individual factors, such as location of the optimal crypt in patients with a thick iris.
The original article can be found here.