IMPACT OF POST-OPERATIVE ADJUSTMENT OF CORNEAL ALLOGENEIC INTRASTROMAL RING SEGMENT (CAIRS) KERATOPLASTY ON VISUAL OUTCOME: A CASE REPORT

This case describes postoperative adjustments to Corneal Allogeneic Intrastromal Ring Segment (CAIRS) keratoplasty, in a patient with suboptimal visual improvement following initial CAIRS implantation. CAIRS keratoplasty is a surgical technique used to improve corneal regularity and visual function in ectasias. Allogeneic corneal ring segments are implanted into laser-dissected intrastromal channels. Despite widely reported benefits in improving uncorrected (UDVA) and corrected distance visual acuity (CDVA), suboptimal outcomes may sometimes occur. We report such a patient who successfully underwent postoperative adjustment, with further improvement in visual acuity. This report highlights the potential for postoperative modification of CAIRS implants to optimise visual outcomes in selected patients.

Dr. Agarwal’s Eye Hospital and Eye Research Centre, Chennai, India.

A 14-year-old female with keratoconus was referred from an external hospital. She had previously undergone CAIRS keratoplasty to reduce corneal irregularity. Pre-operative UDVA was 3/60, and CDVA was 6/12 partial with -2.50DS/-5.00DC @ 80°. Post-CAIRS, vision was 6/36 (6/18 with -4.00DC @ 50°). Expected improvement in visual acuity was not achieved due to several factors, including segment dimensions, size of optical zone used in surgical planning and deviation in CAIRS positioning. Slit-lamp examination, Pentacam, and anterior-segment optical coherence tomography were undertaken and the following adjustments to CAIRS parameters were planned: increased arc length, larger ring segment and smaller optical zone diameter.

The horizontal axis was marked while sitting. The CAIRS was adjusted under the surgical microscope according to the updated surgical plan. The channel was opened with a curved Y-rod, and the old CAIRS was explanted. A double-bladed Jacob CAIRS trephine (Madhu Instruments, New Delhi; CE marked) of appropriate size was used to cut a new manually customised CAIRS ring. The arc was widened using a manual tunneliser. Intraoperative corneal marks were applied, and the customised CAIRS was implanted. Maloney hand-held keratometer confirmed improvement in Placido ring reflection. Final UDVA was 6/12 and CDVA was 6/9 partial with +1.50-1.00DC @ 140°. Topographic parameters also improved.

The aim of CAIRS keratoplasty is to regularise ectatic cornea using allogeneic corneal tissue fashioned into customised ring segments. The extent of corneal flattening is determined by both volume and intrastromal placement of tissue implanted. Various factors result in suboptimal outcomes, such as pre-operative planning discrepancies, intraoperative deviations or improper positioning. A key advantage of CAIRS keratoplasty over current irreversible interventions is the ability to perform post-intervention adjustments. If required, additional segments can be implanted or explanted. In this case, adjustments to arc length and segment dimensions were successfully performed.