LONG TERM OUTCOMES FOR INTRASTROMAL CORNEAL RING SEGMENTS IMPLANTATION FOR KERATOCONUS MANAGEMENT: FIVE AND EIGHT-YEAR RESULTS

Published 2023 - 27th ESCRS Winter Meeting

Reference: O17 | Type: Free Paper Submission | DOI: 10.82333/c01m-9v16

Authors: Ana Margarida Sampaio* ¹ , Álvaro Silva ¹ , Tiago Monteiro ¹ , Nuno Franqueira ¹ , Mariana Oliveira ¹ , José Mendes ¹ , Fernando Vaz ¹

¹Oftalmologia,Hospital de Braga,Braga,Portugal

Purpose

The main purpose of this study is to evaluate the efficacy, safety and stability of ICRS implantation at 8-year long term follow-up.

Setting

Keratoconus is an asymmetric and progressive corneal ectasia. Due to the high irregular astigmatism, myopia and higher order aberrations it carries a significant impact in visual acuity. Intrastromal corneal ring segments (ICRS) implantation is a safe and relatively simple procedure with good visual outcomes. However the impact in the natural progression of the disease and long term effects are not fully validated, with some contradictory published results.

Methods

A retrospective, cohort study was designed. Our sample included 124 eyes submitted to ICRS implantation surgery using manual technique in Hospital de Braga. Visual data (corrected distance visual acuity, CDVA, and uncorrected distance visual acuity, UDVA – logMAR), refractive parameters (sphere, cylinder and spherical equivalent) and topographic data (keratometry, asphericity, coma and pachymetry) were collected. A pre-operative assessment was completed. Postoperatively patients were evaluated at 6 and 12 months and at 5 and 8 years.

Results

A total of 80 patients completed the 8-year follow-up. Mean age was 29 ±12 years and 56%. Around 75% had stage 1 and 2 Amsler-Krumeich corneal ectasia. At 8-years of follow-up UDVA was 0.35±0.32 logMAR, significantly higher than the pre-operative value, 0.90±0.40 (p<0.01). Around 57% achieved UDVA of, at least, 20/40 compared with the 10% pre-operatively (p<0.01). The 8-year CDVA was 0.18±0.18 logMAR, and the preoperative value was 0.41 ±0.30 (p<0.01). More than 73% of patients achieved a CDVA of 20/30, significantly higher than the 35% preop (p<0.01). Safety index at the end of follow-up was 2.15 and the efficacy index was 1.31. Manifest refraction improved significantly after the intervention and remained stable thought follow-up. The topographic data showed a significant decrease in K1, K2 and Kmax. Asphericity and coma improved from 0.81±0.40 to 0.55±0.37 and 2.46±1.22 to 1.67±1.00 (p<0.01), respectively. ICRS explantation was performed in 9 eyes (11%) to improve visual and refractive parameters. In 2 eyes (2.5%) spontaneous ICRS extrusion was observed and 1 (1.3%) case of intraoperative tunnel perforation occurred.

Conclusion

ICRS implantation significantly improve visual, refractive and topographic parameters. This improvement remained stable throughout the 8-year follow-up. This study confirms that ICRS implantation technique is a safe, reversible and minimally invasive surgery with long-term stable outcomes.