Evaluation Of Short Term Outcomes In Eyes With Progressive Keratoconus Undergoing Accelerated , High Fluence, Uva Pulsed ,Oxygen Supplemented Transepithelial Collagen Cross Linking (Acc Hf Uva Pulsed O2 Tecxl)
Published 2024 - 42nd Congress of the ESCRS
Reference: PP01.18 | Type: Free paper | DOI: 10.82333/fbzc-gx37
Authors: Chintan Malhotra* 1 , Divya Challa 1 , Amit Gupta 1 , Arun Jain 1 , Parul Chawla 1
1Ophthalmology,PGIMER,Chandigarh,India
Purpose
Despite formulations having been customized to facilitate penetration of hydrophilic riboflavin across the lipophilic epithelial barrier, outcomes of TECXL are perceived to be affected by the lower UVA penetration and lesser O2 availability across the metabolically active epithelium. Modifications over the years to increase efficacy include higher UVA fluence and increasing availability of oxygen (O2) by pulsing UVA and providing external O2 supplementation. The purpose of this study was to evaluate the 3 month outcomes of eyes with progressive keratoconus undergoing Acc HF UVA Pulsed O2 TECXL
Setting
Prospective , interventional, study conducted at the Cornea Services of a tertiary care institute in India
Methods
Inclusion criteria : Patients with progressive keratoconus (i) age >14 years (ii) thinnest pachymetry of ≥ 375µm on Pentacam iii) Kmax of ≤ 68D iv) Keratoconus grade 1-3 by Belin ABCD classification. Exclusion criteria: i) Advanced cones with subepithelial scarring 15 eyes of 15 patients with progressive keratoconus underwent accelerated high fluence TECXL using 9mW/cm2 of UVA irradiance for 13.3 min (total fluence 7.2J/cm2 ) , 1:1 pulsing of UVA and external O2 supplementation at 1-2 litres/minute. Peschke TE riboflavin formulation containing 0.25 % riboflavin, 1.2% HPMC and 0.01% benzalkonium chloride was used for every 2 minutes for 20 minutes during the saturation phase and continued every 2 minutes during UV exposure.
Results
Mean Kmax at baseline ( 57.1±5.03 D ) and 3 months (56.6 ± 5.2D) was comparable (p=0.06). No eye progressed, 11 stabilized and 4 regressed (decrease in K max by > 1 D).Mean demarcation line depth on ASOCT was 293.6 ± 50.5 µ which was 65.1% of baseline MCT. Total Corneal densitometry decreased at 3 months compared to baseline (p=0.013) . Endothelial cell density (baseline 2545.64±386.04 cells/mm2; 3 months 2390.46±523.90 cells/mm2; p=0.022), hexagonality (baseline 55.00±7.20%; 3 months 50.76±9.06 %; p=0.027) and coefficient of variation (baseline 33.42±4.92; 3 months 36.38±5.86; p=0.018) showed a statistically significant deterioration at 3 months though clinically no evidence of endothelial damage was noted in any patient.
Conclusions
Acc HF UVA Pulsed O2 TECXL demonstrated a demarcation line depth comparable to the 300 micron DL depth reported for ‘epithelium off CXL’ using the ‘gold standard’ Dresden protocol and deeper than that reported for TECXL across published literature. The statistically significant deterioration in the endothelial parameters ( though not reflected clinically) require careful evaluation over time as the external oxygen supplementation may be responsible for deeper CXL effects. Striking a balance between the benefits of a deeper CXL effect versus health of the sensitive structures like the corneal endothelium in oxygen supplemented cross linking procedures thus need to be explored in greater depth in future studies.