To Evaluate And Compare The Ultrastructural Changes On Confocal Microscopy Of High Fluence, Accelerated Transepithelial Collagen Cross Linking (Tecxl) Performed Using Pulsed Uv-A Light And Oxygen Supplementation.

To Evaluate and Compare the Ultrastructural  changes on Confocal microscopy( Heidelberg Retinal Tomograph HRT III )and on Anterior segment ocular coherence tomography (ASOCT) of High fluence, Accelerated Transepithelial Collagen Cross Linking (TECXL) performed using Pulsed UV-A light with that performed using a combination of Pulsed UV-A and Oxygen Supplementation.

Cornea clinic services of tertiary eye care hospital

The study was a prospective, interventional, randomized controlled study. All the 44 patients with progressive keratoconus were randomized into 3 groups and underwent TECXL.Group A used 3mW/cm2 of continuous UVA exposure for 30min (total fluence 5.4J/cm2) ,both group B and group C used  9mW/cm2 of UVA irradiance for a duration of 13.3 min (total fluence 7.2J/cm2 ) with 1:1 pulsing of UVA ,whereas external oxygen supplementation was given by customized goggles in group C .In vivo confocal microscopy  was done to determine effect of cxl on anterior, middle and posterior stromal keratocyte density and on sub basal corneal nerve fibre density (CNFD). Demarcation line depth (DL)was assessed using both ASOCT and confocal microscopy

 A decrease in anterior and middle keratocyte density was noted in all three groups from baseline to 1 month  (233.14±67.37to168.00±38.08, 206.25±54.80 to 147.36±41.9 , 205.76±43.96 to179.30±52.29)(0.001,002 and 0.023respectively), while significant decrease at the end of 3 months  noted in Group A only.The posterior keratocyte density remained unchanged from baseline to 3 months post CXL ( all p’s >0.05).In all the  groups the CNFD decreased at 1 month(p=0.001),from 1 month to 3 months it showed an increasing trend in all the three groups. The DL depth on ASOCT was 269.62±53.495,270.08±88.281 and 293.64±50.456 (p=0.558) and on confocal microscopy was ( 240.42 ± 51.72, 245.07 ± 46.48 and 239.33 ± 46.80µ) for group A,B and C respectively.

Ultrastructurally the oxygen supplementation group demonstrated quicker recovery of anterior and middle keratocyte density at 3 months. Mean DL depth ,often considered as a surrogate mother of an effective CXL procedure was comparable across groups ( at 60-65% of the baseline pachymetry)as well as to results reported for epithelium -off CXL in literature..