Abstract
Purpose :
Corneal crosslinking (CXL) is known as a procedure that halts the progression of keratoconus using riboflavin and ultraviolet-A (UVA) light. To avoid endothelial cell density (ECD) loss due to UVA, we should swell the corneal stroma with a hypotonic solution to obtain a 400µm thickness during UVA irradiation. However, reaching 400µm is difficult in some cases. We retrospectively investigated the effect of CXL on the ECD comparing the corneal stromal thickness before and during the CXL procedure.
Methods :
Sixty-three eyes of 49 patients with progressing keratoconus (38 males and 11 females, 21.7 ± 6.3 years-old) were investigated. CXL was performed using the epithelial off method. Following 0.1% riboflavin instillation for 20 minutes, the thinnest corneal thickness was measured by pachymetry around the apex of the corneal cone. When the thickness was less than 400µm, a hypotonic solution was instilled until the corneal stroma swelled to 400 µm or more. UVA was irradiated at 3.0 mW/mm2 for 30 minutes or 18.0 mW/mm2 for 5 minutes. The eyes were divided into 2 groups; eyes with no ECD decrease, and eyes with a decrease of 10% or more at 1 month after CXL compared to their preoperative value. Patients’ age, sex, pattern of ultraviolet-A irradiation, preoperative keratometric readings, thinnest corneal thickness (TCT), and ECD were analyzed.
Results :
The average ECD count for all of the eyes was 2,664.9 ± 368.7 cells/mm2 preoperatively and decreased to 2,632.0 ± 497.0 cells/mm2（p=0.0147）at 1 month after CXL, however, this returned to the preoperative value at 3 months and thereafter. Twenty-nine eyes （46.3%）revealed an ECD decrease at 1 month after CXL. Between the eyes with and without ECD decrease, the preoperative TCT was not significantly different (406.5 ± 46.0 μm vs 406.2 ± 69.4 μm), however, the TCT just before the ultraviolet-A irradiation was 419.4 ± 49.0 μm in eyes with an ECD decrease and 434.1 ± 51.6 μm in eyes without an ECD decrease (P=0.0427). Other factors were not significantly different between the groups.
Conclusions :
More than 40% of eyes showed transient ECD decrease after CXL. Obtaining enough corneal thickness by swelling the corneal stroma just prior to the UVA irradiation seemed to be necessary in order to avoid ECD loss after CXL using riboflavin and ultraviolet-A.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.