Posters

Evolutive keratoconus treated by customized topography-guided corneal cross-linking: clinical results

Poster Details

First Author: M. Cassagne FRANCE

Co Author(s):    K. Pierne   S. Galiacy   P. Fournie   F. Malecaze           

Abstract Details

Purpose:

The gold standard, conventional corneal collagen crosslinking (C-CXL) increases the rigidity of the entire treated cornea of patients with progressive keratoconus. Biomechanical studies suggest the mechanical loss of this disease is localized to the cone. This study aims to evaluate a method for selectively stiffening the diseased region of the cornea using topography guided customized crosslinking (TG-CXL).

Setting:

A single-center, comparative clinical study was performed that compared TG-CXL to C-CXL. 33 eyes were treated with TG-CXL and 32 with C-CXL. Patients were followed for 6 months postoperatively (M6). Key inclusion criteria were: patients ≥16 years old, with progressive keratoconus and pachymetry ≥400 µm.

Methods:

The Dresden Protocol was applied for C-CXL. For TG-CXL, the epithelium was removed over the region of the cornea to be treated with UVA (30mW/cm2 pulsed irradiance). Riboflavin was applied every two minutes for 10 minutes. The UVA total energy dose and pattern were programmed according to the patient topography. The treated region of the keratoconus cone was compared to the untreated cornea 180 degrees away (opposite area) by OCT and confocal microscopy. Keratometric change and corneal symmetry (index of inferior (I) to superior (S) cornea) were evaluated by corneal topography. Best-corrected visual acuity (BCVA) was also assessed.

Results:

BCVA improved in 50% of TG-CXL and in 43.7% of C-CXL eyes (p>0.05). A stromal demarcation line was observed in both treatment groups, with similar depth within the region of the cone (p=0.9244). A shallower demarcation line depth was observed within the opposite area in TG-CXL (p<0.001). Nerve and cell densities showed less damage and faster healing in the opposite area than within the cone area in TG-CXL group (p<0.01). Maximum keratometry and I index were flattened by 1.29D (p<0.01) and 1.017D (p<0.001) respectively in TG-CXL and steepened by 0.44D (p=0.2282) and 1.4D (p=0.1748) respectively in C-CXL at M6.

Conclusions:

Within the treatment zone positioned at the apex of the cone, TG-CXL has similar biological effects as C-CXL. This was demonstrated by similar stromal demarcation line depth within the treated area, as well as a similar decrease in nerve density and keratocytes. TG-CXL induces a gradient in treatment effect between the cone area and the untreated, opposite area. Compared to C-CXL, the TG-CXL procedure also induces a more significant inferior corneal flattening effect at 6 months.

Financial Disclosure:

NONE