Evaluating target intraocular pressures in primary congenital glaucoma

Abstract

Purpose: The aim of this study was to evaluate long-term intraocular pressures that provide stabilization/reversal of glaucomatous neuropathy after surgery in primary congenital glaucoma (PCG). Methods: Prospective evaluation of consecutive PCG patients who underwent trabeculectomy-trabeculotomy and followed up for ≥2 years. Records of regularly performed examination under anesthesia were maintained to ascertain intraocular pressure, (IOP), fundus, refraction and corneal diameter. Outcomes – Primary: cup: disc ratio and intraocular pressure, Secondary: corneal changes and refractive error Results: A total of 174 eyes of 108 children with PCG had a preoperative IOP of 22.44 ± 9.5 mm Hg. Postoperative review IOP was 11.8 ± 4.5 mm Hg, cup-disc-ratio was 0.52 ± 0.23 and corneal diameter was 12.75 ± 0.9 mm. Primary outcomes: Linear regression analysis showed a significant positive correlation of review IOP with cup disc ratio, P = 0.004. 67.9%, of eyes at a review IOP range of 6-12 mm Hg showed reversal, 14.1%, were stable, at 6-15 mm Hg, while 3.84% showed an increase in cup: disc ratio 16-22 mm Hg. Patients operated before 6 months of age had a significantly smaller final cup-disc ratio, P = 0.0013. Patients with a final cup: disc ratio of >0.9 were significantly older at surgery, P < 0.001. Secondary outcomes: There was a positive correlation of final myopia with review IOP on linear regression analysis, P = 0.012. The final spherical error in eyes having cup disc ratio of ≤ 0.5 was –0.96 ± 4.5 diopters, as against -3.45 ± 7.7 diopters in eyes having cup-disc ratio of 0.6-0.8 and -3.8 ± 6.9 diopters in eyes with cup disc ratio of ≥0.9, P = 0.015. There was no significant change in corneal diameter. Conclusion: Patients operated after 6 months of age had a larger final cup: disc ratio, while postoperative review intraocular pressures over 2 years of at least ≤15 mm Hg in primary congenital glaucoma eyes, commonly lead to reversal/stability of the neuropathy, and a lower incidence and degree of myopia.