Stromal surface topography-guided ablation as a repair tool for irregular stromal surface

Session Details

Session Title: Presented Poster Session 11: Refractive Surgery New Techniques / Instrumentation / Devices 1

Session Date/Time: Sunday 14/09/2014 | 15:00-17:00

Paper Time: 16:30

Venue: Pod 2 (Poster Village)

First Author: : D.Reinstein UK

Co Author(s): :    M. Gobbe   T. Archer   G. Youssefi   H. Sutton     

Abstract Details

Purpose:

To present the concept of using stromal surface topography-guided ablation for therapeutic repair after a complicated primary corneal refractive procedure.

Setting:

London Vision Clinic, London, UK

Methods:

The principal and first ever case of stromal surface guided therapeutic retreatment for short nasal flap after primary LASIK performed in September 2000 are presented. The Artemis very high-frequency digital ultrasound arc-scanner was used to obtain layered corneal pachymetry including the epithelial thickness profile. Corneal front surface elevation was measured with Orbscan II. The height of the stromal surface was then calculated by subtracting the epithelial thickness data from the corneal front surface elevation data. The ablation profile applied to the eye was calculated based on the shape of the stromal surface rather than the corneal surface to account for epithelial masking of the stromal irregularity. The treatment was performed by linking the ultrasound epithelial pachymetric data with the Technolas 217z Bausch and Lomb Topolink software. Post-operative data was available at day 30 and 13 years after surgery.

Results:

One month after treatment, the epithelial thickness map demonstrated that the difference in thickness between the thinnest and thickest points located 2.5mm nasally, where the primary ablation had been performed on the underside of the flap, was reduced by 26 µm. The axial difference map demonstrated an increase in corneal curvature of approximately 4D where the cornea was flattest nasally, therefore reducing the corneal asymmetry. The anterior elevation difference map also showed a reduced depression nasally. The patient reported noticeable improvement of her night vision. This case also demonstrated a large difference in the shape of the ablation profiles between a corneal topography-guided and a stromal topography-guided, indicating that topography-guided profile would have resulted in correcting less irregularity.

Conclusions:

This case example provides the first report of stromal surface topography-guided treatment. It demonstrated a significant reduction in the irregularity of the stromal surface and an improvement in the topography as well as the visual quality. Stromal surface topography-guided could potentially to become the tool of the future for therapeutic repairs as it offers advantages over the current alternative of trans-epithelial PTK and corneal surface topography-guided ablation.

Financial Interest:

One or more of the authors... has significant investment interest in a company producing, developing or supplying product or procedure presented