Reversal of optic disc cupping after glaucoma surgery analyzed with a scanning laser tomograph

Objective: To detect and quantitate changes in optic nerve morphology after glaucoma surgery using the Heidelberg Retina Tomograph (HRT, Heidelberg In struments, Heidelberg, Germany). Design: Nonconsecutive observational case series. Participants and Intervention: The authors prospectively enrolled 21 adult patients undergoing incisional glaucoma surgery for progressive glaucoma da mage. Quantitative analysis of the optic nerve head by scanning laser tomog raphy and automated perimetry were performed before and after glaucoma surg ery. Main Outcome Measures: Changes in optic nerve parameters were subjected to linear regression analysis with respect to percent of postoperative reducti on of intraocular pressure (IOP), as well as with respect to age, refractio n, preoperative cup,disc ratio, and change in visual field parameters. Results: Seventeen patients had pre- and postoperative images suitable for analysis, Mean IOP at the time of image acquisition before surgery was 30.5 +/- 12 mmHg, and after surgery 11.8 +/- 5.2 mmHg (mean follow-up, 26 +/- 7 weeks). Eleven of 13 (85%) patients having IOP reduction of greater than 4 0% showed improvement in optic disc parameters. All four patients with less than 25% reduction in IOP showed worsening of most parameters. Changes in optic disc parameters were highly correlated with percent IOP reduction and with age. The parameters in which change most strongly correlated with per cent change of IOP were cup area, rim area, cup:disc ratio, and mean (up de pth teach, P < 0.005), The age of the patient correlated highly with change in maximum cup depth (P < 0.005), Refraction and clinically determined cup :disc ratio correlated poorly with changes in measured optic disc parameter s. Clinical improvement in visual fields was correlated with the degree of improvement of cup:disc ratio (P = 0.025), Conclusion: Most patients showing a 40% lowering of IOP after glaucoma surg ery show improved optic nerve morphology as measured by the HRT. The amount of improvement correlated highly with the percent reduction of IOP.