Changes in optic disc parameters after intraocular pressure reduction in adult glaucoma patients

To quantitatively evaluate the change in the optic disc topographic parameters associated with reduction in the intraocular pressure (IOP) after trabeculectomy in adult patients with glaucoma.

A series of 22 patients (mean age: 45.7+/-15.1 years) with several types of glaucoma were examined for various parameters of optic disc before and after trabeculectomy. Cup area, cup-to-disc area ratio, cup volume, rim volume, mean cup depth, and maximum cup depth were determined by means of laser scanning tomography (LST), and the parameters were correlated with the degree of postsurgical IOP decrease.

The IOP in adult glaucoma patients showed significant reductions after trabeculectomy. The values for all topographic parameters examined. except cup volume, showed statistically significant postsurgical changes as compared to the presurgical values. Of all postsurgical changes in parameters. the increase in the rim volume was the most noticeable; it was remarkably evident in those eyes with postsurgical IOP levels less than 15 mm Hg. It was also demonstrated that the anterior displacement of the glaucomatous cupping may occur after surgery.

It is obvious that optic disc parameters can change after IOP reduction after successful surgery in adult glaucoma patients as well as in infantile glaucoma patients. The site of changeable glaucomatous optic cupping is topographically variable among patients and it may be related to the presurgical shape of the optic cup.