Abstract
Purpose :
Corneal collagen cross-linking (CXL) using riboflavin and ultraviolet-A light (UVA) is a minimally invasive treatment used to prevent progression of keratoconus. Recently, some have advocated rinsing the cornea with balanced salt solution (BSS) prior to UVA exposure to remove the superficial riboflavin film and prevent UVA shielding. This study assesses the impact of rinsing on CXL effectiveness by examining the enzymatic resistance of the tissue following treatment.
Methods :
40 porcine eyes (with corneal epithelium removed) were assigned to 4 groups. Group 1 remained untreated. Groups 2, 3 and 4 received a 10-min application of 0.1% riboflavin/HPMC eyedrops. Group 3 was immediately exposed to 9 mW/cm2 UVA for 10-mins and Group 4 received the same UVA exposure after a corneal surface rinse (0.25 ml BSS). Central corneal thickness (CCT) was recorded at each stage of treatment. Trephined 8.0 mm central corneal buttons (n = 5 per group) were subjected to 0.3% collagenase digestion at 37°C. The samples were monitored at 1-hr intervals for the first 30-hrs, and 2-10hr intervals thereafter, to determine the time required for complete digestion.
Results :
A 10-min application of riboflavin/HPMC solution to the de-epithelialised cornea led to an increase in CCT (54 µm ± 26; p<0.01) (Fig. 1). During UVA exposure, the CCT of the unrinsed CXL corneas (Group 3) returned to pre-treatment levels but the CCT of the BSS-rinsed CXL corneas (Group 4) continued to rise above the pre-treatment value (75 µm ± 15; p<0.01). All CXL-treated corneas displayed a 3-to-4-fold greater resistance to collagenase digestion than non-irradiated corneas. Complete digestion occurred at 12 ± 0.9 and 12 ± 0.8 hours in the untreated (Group 1) and riboflavin only treated (Group 2) corneas respectively and at 36-49 hours in the CXL treated corneas (Groups 3 and 4). There were no notable differences in enzymatic resistance between the two CXL groups.
Conclusions :
Both CXL protocols were equally effective at enhancing the resistance of the cornea to collagenase digestion, although BSS-rinse CXL may be advantageous for the treatment of thin corneas which require tissue swelling. Further studies are needed to assess the impact of different volumes of BSS rinse on CXL effectiveness.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.