Nonpenetrating deep sclerectomy: a 6-year retrospective study

Nonpenetrating trabeculectomy, also called nonpenetrating deep sclerectomy (NPDS), is a filtering surgery where the internal wall of Schlemm's canal is excised, allowing subconjunctival filtration without actually entering the anterior chamber. This, technique was developed to minimize the complications of trabeculectomy. The authors investigated its safety and efficacy in a retrospective noncomparative study.

A total of 258 eyes (179 patients, mean age 61.4 +/- 11.56 years) with uncontrolled open angle glaucoma with prior medical therapy were treated. NPDS with a biocompatible collagen device (157 eyes) sutured to deep scleral bed or with the use of a 5-fluorouracil sponge (90 eyes) were analyzed. The main outcome measure was postoperative intraocular pressure (IOP) with an average follow-up of 54.4 +/- 17.07 months (range 1-85). Efficacy was determined 1 month, 3 months, and every 6 months after the procedure for 6 years.

Mean preoperative IOP was 24.47 +/- 5.92 mmHg. Mean postoperative IOP was 14.44 +/- 5.31 mmHg (average lowering of the IOP was 38.94 +/- 23.81%) at 1 month, 15.16 +/- 4.57 mmHg (35.73 +/- 21.35%) at 3 months, 15.87 +/- 4.24 mmHg (32.45 +/- 20.52%) at 6 months, 16.32 +/- 4.53 mmHg (29.96 +/- 23.69%) at 12 months, 17.12 +/- 4.45 mmHg (26.51 +/- 23.93%) at 18 months, 16.77 +/- 4.44 mmHg (28.18 +/- 21.73%) at 24 months, 16.43 +/- 4.15 mmHg (28.89 +/- 23.69%) at 30 months, 16.34 +/- 4.12 mmHg (30.05 +/- 21.61%) at 36 months, 16.16 +/- 4.01 mmHg (30.06 +/- 22.55%) at 42 months, 15.71 +/- 3.74 mmHg (32.49 +/- 19.08%) at 48 months, 15.61 +/- 3.48 mmHg (31.26 +/- 21.01%) after 5 years, and 15.81 +/- 3.79 mmHg (33.73 +/- 20.9%) after 6 years. YAG goniopuncture was performed in 47.3% of cases with a mean follow-up of 12 +/- 13 months. These goniopunctures were effective in lowering IOP after a long-term follow-up (24 months). Additional 5-fluorouracil injections were used in 7% of cases. Visual field (Octopus or Humphrey mean defect and corrected loss variance or loss variance) was not modified (p < 0.01). Number of preoperative glaucoma medications was 2.01 +/- 0.58 and number of postoperative glaucoma medications was 0.85 +/- 0.92. Complications were peroperative microperforations in 27 eyes (10.5%), shallow anterior chamber in 2 eyes, hyphema in 2 eyes (0.8%), cataract in 5 eyes (2%), and dellen in 1 eye (0.4%). No cases of endophthalmitis or choroidal detachment were found. After surgery, 23 eyes (8.9%) required a new filtering surgical procedure, and diode laser cyclophotocoagulation was necessary in 2 eyes (0.8%). The probability success rate, defined as an IOP lower than 21 mmHg, was 66.46% (Kaplan Meier) at 60 months off all glaucoma medications and 80.32% with medical or new surgical treatment.

NPDS appears to be an effective and safe filtering procedure for lowering IOP and could be an alternative to trabeculectomy in open angle glaucoma with the advantage of having fewer complications.