Visual, Refractive And Topographic Results After Implantation Of Intrastromal Corneal Ring Segments In Patients With Nipple Phenotype Of Keratoconus

Keratoconus is a common, idiopathic corneal disorder with a substantial impact on

the vision-related quality of life. This study aims to evaluate the visual, refractive and

topographic outcomes of intrastromal corneal ring segments (ICRS) implantation in patients

with nipple phenotype of keratoconus.

This retrospective cohort study included 29 eyes from 29 patients with nipple

phenotype of keratoconus submitted to implantation of ICRS using a manual technique at

the Hospital de Braga - between July 2011 and December 2016 - with a minimum

postoperative follow-up time of 6 months. Uncorrected distance visual

acuity (UDVA), corrected distance visual acuity (CDVA), subjective refraction, corneal

topography and corneal pachymetry were evaluated preoperatively and at 6 months

postoperatively.

At 6-months postoperatively, CDVA and UDVA were 0.26±0.15 and 0.50±0.20 logMAR, respectively, with a mean gain of 0.74±0.21 (p<0.001) and 0.66±0.20 logMAR (p<0.001). Safety and efficacy indices was 2.17±2.21 and 1.20±1.44, respectively. Regarding CDVA, 72.4% eyes gained 1 or more Snellen lines and 24.1% lost 1 or more lines. All refractive parameters revealed a significant postoperative improvement (p<0.001). Q-value (p<0.001), coma (p=0.003), anterior K1 (p<0.001), anterior K2 (p<0.001), anterior maximum K (p=0.002) and posterior K2 (p=0.006) improved significantly after surgery. No significant pachymetric changes were observed (p=0.16). No cases of ring segment perforation or extrusion, or vision threatening complications were reported.

ICRS implantation is an effective surgical procedure to improve visual,

refractive and topographic parameters even in patients with nipple keratoconus. We found

an excellent safety profile, with no intraoperative and postoperative complications in the first

6-months of follow-up.