Corneal tomography and endothelial cell density after Paul glaucoma implant surgery

To evaluate changes in corneal tomography, pachymetry and endothelial cell density (ECD) following Paul Glaucoma Implant (PGI) surgery.

Seventy-three patients were prospectively examined. Repeated measures anova was used to analyse corneal tomography, corneal thickness and ECD at baseline, 6 and 12 months.

PGI surgery was not associated with clinically meaningful changes in corneal tomography parameters. Simulated astigmatism and posterior astigmatism remained stable over 12 months. Simulated average keratometry showed a small but statistically significant flattening (≈0.3 diopters), whereas posterior average keratometry remained unchanged. Although some changes reached statistical significance, their magnitude was minimal and unlikely to be clinically relevant. Central corneal thickness remained stable, but pachymetry in the tube quadrant increased in the operated eyes, while adjusted pairwise comparisons were non-significant. Central ECD did not change significantly after surgery (p = 0.67). In contrast, paracentral (-2.9%) and peripheral (-4.7%) ECD values declined significantly over 12 months (p = 0.03 and p = 0.001, respectively) and study eyes consistently showed lower values than contralateral control eyes. However, PGI surgery did not accelerate the rate of cell loss, as the time × eye interaction was not significant.

PGI surgery did not induce progressive changes in corneal astigmatism or pachymetry during the first postoperative year. Central ECD remained stable, while paracentral and peripheral regions showed a moderate decline. PGI did not increase the rate of endothelial cell loss and the observed reduction was lower than previously reported for other glaucoma drainage implants.