# Evaluation of perioperative pachymetry of thin corneas during corneal crosslinking using hypo-osmolar riboflavin and hydroxypropyl methylcellulose

## TL;DR

This study examines changes in corneal thickness during crosslinking treatment for keratoconus and finds significant variations linked to pre-surgery measurements.

## Contribution

The study introduces a method to evaluate corneal thickness changes using hypo-osmolar riboflavin and identifies correlations with pre-surgical keratometry.

## Key findings

- A significant increase in corneal pachymetry was observed during the procedure.
- One year post-treatment, there was a significant reduction in both pachymetry and Kmax values.
- A 3.05 µm increase in pachymetry per diopter was noted after epithelium removal.

## Abstract

This study aimed to analyze variations in intraoperative corneal thickness during
corneal cross-linking in patients with keratoconus and to investigate its possible
correlation with presurgical maximal keratometry (Kmax) and pachymetry.

This was a prospective case series. We used a method similar to the Dresden protocol,
with the application of hydroxypropyl methylcellulose 0.1% hypo-osmolar riboflavin in
corneas between 330 and 400 µm after epithelium removal. Corneal thickness was
measured using portable calipers before and immediately after epithelium removal, and 30
and 60 min after the procedure.

The 30 patients in this study were followed up for one year. A statistically
significant difference was observed in pachymetry values during the intraoperative
period (p<0.0001) and an increase of 3.05 µm (95%C1: 0.56-5.54) for each
diopter was seen after epithelium removal (p0.019). We found an average Kmax difference
of —2.12 D between men and women (p0.013). One year after treatment, there was a
statistically significant reduction in pachymetry (p<0.0001) and Kmax (p0.0170)
values.

A significant increase in pachymetry measurements was seen during the procedure, and
most patients showed a regression in Kmax and pachymetry values one year after
surgery.