Abstract
Purpose: :
Trabeculectomy is currently the mainstay in medically refractory glaucoma treatment. Nonpenetrating deep sclerectomy (NPDS) is a related glaucoma filtering procedure that aims to control IOP by enhancing drainage of aqueous humor without disrupting the trabecular endothelial layer. Because this may reduce the risk of early post-op hypotony and hyphema, certain higher-risk patients might be considered for NPDS to minimize post-surgical complications.
Methods: :
A quality assurance analysis was performed of 87 consecutive eyes that underwent Mermoud-style ruby-knife/diamond blade NPDS procedures with confirmation of an intact internal trabeculum prior to three 1-min Weck-cel applications of 0.4 mg/ml Mitomycin-C, one to the scleral lake and two between the external scleral flap and tenons capsule. Perisulcal limbus-based conjunctival incisions were used, closed in two-layers with 8-0 polyglycan suture on a tapered BV needle. The 5x6 mm rectangular scleral flaps beneath were closed with 3 interrupted 10-0 nylon sutures posteriorly. No collagen or other implants were placed. Paired t-test assessments of pre-op SITA full-threshold 30-2 Humphrey Mean Deviation (MD) versus 1-yr post-op MD, and of pre-op IOP, total glaucoma medications (topical and oral), and acuity versus corresponding 3-,6-,9-,12-, & 18-mo post-op values were performed. Linear regression change analysis to assess association between variables was also performed.
Results: :
Mean Humphrey visual field MD improved from -12.20 ± (sem)0.95 dB pre-op to -10.85 ±0.95 at one year (p= 0.002). Over 90% of participants had undergone perimetric testing multiple times prior to their surgery, and exclusion of subjects without prior perimetric experience did not significantly alter these values. Sustained therapeutic-level IOP reduction was seen at all 5 post-op intervals, with no tachyphylactic regression (from pre-op 22.2 ±0.9 mmHg to 12.4 ±0.4 at 1 yr, and 11.7 ±0.5 at 18-mo (p<0.0001). Mean visual acuity remained stable throughout the study period. Incidence of hypotony (IOP<4 mmHg) was low (6/410; 1.5%), and there were no hyphemata observed. Mean glaucoma medications dropped from 3.0 ±0.12 to 0.3 ±0.07 at 18 months (P<0.0001). While most eyes demonstrated visual field improvement and IOP reduction, no correlation was found between the extent of these changes.
Conclusions: :
NPDS is an underutilized and potentially valuable glaucoma surgical option, with these data showing substantial (>40%) sustained IOP reduction to safe therapeutic levels through 18 months, with significant improvement in visual field performance not attributable to learning effect, minimal postoperative morbidity, and a 90% reduction in reliance on medical therapy.
Keywords: clinical (human) or epidemiologic studies: outcomes/complications • visual fields • intraocular pressure