Tube ligation in Ahmed glaucoma valve surgery may effectively reduce the rate of postoperative complications in patients who undergo this procedure, without compromising surgical success rate or visual outcomes, according to research published in the Journal of Glaucoma.
Researchers conducted a retrospective, matched case control study of patients who underwent Ahmed glaucoma valve surgery with tube ligation between June 2015 and December 2017. Each case was matched with controls who underwent the same surgery study population included 147 eyes (49 cases in the ligated group and 98 cases in the nonligated group). No statistical between-group differences in age, sex, preoperative intraocular pressure (IOP), baseline visual acuity, previous glaucoma surgeries, and previous ocular surgeries were noted. In the ligation group, 30.6% of cases involved polypropylene ligature; the remaining cases underwent tube ligation with polyglactin. Mean time-to-surgery-to-suture lysis in the polypropylene group was approximately 30 days.
At the last postoperative visit, investigators found a statistically significant decline in mean IOP in both groups (32.9±9.5 to 16.7±6.3 mm Hg and 34.3±8.3 to 17.3±8.0 mm Hg; P <.01 for both). Beginning at postoperative visit 2 onwards, mean IOP was similar between groups.
Mean number of glaucoma medications was higher in the ligated group compared with the nonligated group across all postoperative visits, with a statistically significant different from visit 1 to visit 5 (1.39±1.53 vs 0.11±0.60 and 2.06±1.23 vs 1.59±1.40; P <.01 and P =.04, respectively). Difference in mean number of medications was not statistically significant from visit 6 on.
A Kaplan-Meier survival analysis of surgical success found that at 12 months, the overall surgical success rate was 83.2% and 81.2% in the ligated and nonligated groups, with a rate of complete success of 14.3% and 29.6%, respectively. Surgical revision was required in more patients in the nonligation group (15.3%); this group also experienced higher rates of overall postoperative complications.
Study limitations include the retrospective design, the collection of data from multiple surgeons with varying ligation techniques, and a lack of data on long-term effects of ligation on the efficacy of Ahmed glaucoma valve surgery overall.
“Future randomized clinical trials with a longer period of follow-up are required to further consolidate the findings of the current study and explore the long-term effects of ligation on the efficacy of [Ahmed glaucoma valve] surgery,” the researchers concluded.
Al Owaifeer AM, Alobaida I, Alrefaie S, Malik R, Aljadaan I. The effect of tube ligature on the safety and efficacy of Ahmed glaucoma valve surgery. J Glaucoma. 2020;29(12):1173-1178. doi:10.1097/IJG.0000000000001661.