Corneal innervation, corneal mechanical sensitivity, and tear fluid secretion after transscleral contact 670-nm diode laser cyclophotocoagulation

Abstract

Purpose: To examine the effect of 670-nm diode laser cyclophotocoagulation on corneal morphology, density of corneal subbasal nerves, corneal mechanical sensitivity, and the rate of tear fluid secretion in human eyes.

Patients and methods: Transscleral contact cyclophotocoagulation was performed in 10 eyes of 10 consecutive patients on 180 degrees of the pars plicata of the ciliary body, using a 670-nm diode laser (power = 430 mW, application time = 10 seconds). In vivo confocal microscopy, with special attention to corneal morphology and the density of the subbasal nerves in the central and inferior perilimbal cornea, was performed preoperatively, and at 3 days and 1 month postoperatively. Corneal mechanical sensitivity was tested preoperatively, and at 3 days and 1 month postoperatively, using a Cochet-Bonnet esthesiometer. The rate of tear fluid secretion was measured preoperatively and 1 month postoperatively, using the Schirmer basic secretion tear test with topical anesthesia.

Results: After cyclophotocoagulation, in vivo confocal microscopy did not reveal any changes in any of the corneal layers or in the corneal subbasal nerves. After treatment, as compared with baseline (paired samples test, > 0.05), there was no statistically significant change in the mechanical sensitivity values in any part of the cornea or in the Schirmer basic secretion tear test result.

Conclusion: The results of this preliminary study suggest that cyclophotocoagulation with the 670-nm diode laser does not impair corneal innervation.