gms | German Medical Science

Purpose: After Descemet Membrane Endothelial Keratoplasty, the air-gas compound in the anterior chamber can lead to a postoperative increase in intraocular pressure up to pupillary block. Laser iridotomy or surgical iridectomy is performed to prevent these painful and sight-threatening elevations. Our study aims to compare the safety profiles of the two procedures.

Methods: We included a total of n = 196 eyes of N = 178 patients who underwent surgery. Of these, 124 eyes received intraoperatively an iridectomy (63,3%, group A) and 72 an iridotomy one day before the surgery (36,7%, group B). Demographic characteristics were similar between both groups. The primary endpoint was the risk of elevated intraocular pressure. Secondary endpoints were the clinical outcome (measured by endothelial cell count, visual acuity, central corneal thickness) and the identification of other risk factors for pressure elevation.

Results: The preoperative intraocular pressure didn’t differ significantly between the groups (p = .643). However, group B showed a significant increased risk of reaching postoperative pressure values above 50 mmHg (p = .021). On average, group B showed higher pressure immediately after surgery compared to group A (p = .004; ω² = .04), as well as greater immediate pressure changes from preoperative to postoperative levels (p = .011, ω² = .03). This difference resolved after 6 weeks. In pseudophakic eyes, a greater anterior chamber depth was associated with smaller immediate pressure difference (p = .026; ω² = .06) and pressure after 6 months (p = .013, ω² = .43). Factors like previous uveitis, Pseudoexfoliation syndrome or glaucoma had no influence on the immediate pressure difference. Interestingly, 6 months after surgery, the visual acuity improvement was greater in group B compared to group A (p = .032, ω² = .11). At all follow-up controls prior six months, visual acuity didn’t significantly differ between the groups.

Conclusions: This study showed that preoperative laser iridotomy is an alternative to surgical iridectomy, but sufficient postoperative pressure control and appropriate preoperative counselling are crucial as laser iridotomy is associated with a higher risk of peak pressure values > 50 mmHg and immediate pressure differences.