Corneal nerve changes by anti-glaucoma medications examined by in vivo confocal microscopy

Aim: To evaluate the effects of antiglaucoma eye drops on corneal nerves by in vivo confocal microscopy (IVCM).

Methods: This study comprised 79 patients diagnosed with glaucoma and 16 healthy control individuals. Among the glaucoma patients, 54 were treated with medication, while 25 remained untreated. Central corneal images were evaluated by IVCM, and then ACCMetrics was used to calculate the following parameters: corneal nerve fiber density (CNFD), branch density (CNBD), fiber length (CNFL), total branch density (CTBD), fiber area (CNFA), fiber width (CNFW), and fractal dimension (CNFrD). The correlation between IVCM parameters and drugs was evaluated using non-parametric measurements of Spearman's rank correlation coefficient.

Results: The CNFD was reduced in glaucoma groups compared to healthy subjects (P<0.01). Patients using anti-glaucoma medications exhibited poorer confocal parameters compared to untreated patients. As the number of medications and usage count increased, CNFD, CNBD, CNFL, CTBD, CNFA, and CNFrD experienced a decline, while CNFW increased (all P<0.01). For the brinzolamide-therapy group, there was a significant decrease in CNFD and CNFL compared to the other monotherapy groups (P<0.001). In the absence of medication, CNFD in males was lower than that in females (P<0.05). Among patients under medication therapy, CNFD remained consistent between males and females.

Conclusion: Antiglaucoma eye drops affect the microstructure of corneal nerves. IVCM and ACCMetrics are useful tools that could be used to evaluate the corneal nerve changes.