Customised Corneal Intrastromal Ring Segments In Keratoconus With A Low Energy Femtosecond Laser

To evaluate the efficacy of corneal allogenic intrastromal ring segments in keratoconus by cutting the ring segments with a low energy femtosecond laser and customizing the treatment. 

Tygervalley Eye and laser Clinic , Cape Town , South Africa

A low energy femtosecond laser was used to cut the tunnels and segments, by the author. The segments were placed over the steep area of the ectasia. The sagital topographic map of the MS39 anterior segment tomograph was used. The Brisbane CAIRS planning software was used. AWWAD Nomogram was used as a guideline. The segments were placed at either 250 microns or 300 microns.  

Uncorrected and best corrected visual acquity was recorded. Pre-opperative and post-opperative MS39 scans were taken. 

The presentation is a series of case studies showing the efficacy after 3-6 months prior to any further intervention. The presentation includes videos of the preparation of the allogenic ring segments, and the surgical technique of implantation. 

The visual results showed increased uncorrected and best corrected visual acquity in 100% of cases. 

At a later stage 2 cases segments were removed due to complications.

1 of these cases had trauma and developed a corneal ulcer 3 months after the original sugery. This was unrelated to the CAIRS procedure. 
In another case who had extrusion of a intracorneal ring segment and previous corneal ulcer the CAIRS segment which was implanted, was too superficial and was removed 8 weeks after the surgery. 

In 100% of the cases, there was an improvement in uncorrected visual acquity and best corrected acquity. In all these cases it was not possible to get functional vision either with glasses or contact lenses prior to surgery. All patients were very happy and their quality of life much improved. 

The two patients that had segments removed between 8 and 12 weeks, intially had improved vision.