Intrastromal Corneal Ring Segments For Keratoconus Patients: Up To 12.5 Years Follow Up

Intra stromal corneal ring segments (ISCRS) are considered a viable option for refractive error management in keratoconus . However, long term follow up is still limited. We report the results of a long term follow up extending to 12.5 years.

Hospital-based descriptive study conducted on keratoconus patients with ISCRS.

 Patients who performed their ISCRS between 2008 and 2013 were recruited. For each patient, we obtained baseline and latest follow up data on uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) , subjective refraction, slit-lamp examination and corneal tomography. We calculated the change in visual acuity, keratometry  in relation to the duration from ring implantation to latest follow up in months.

A total of 68 patients were included. The mean duration of follow up was 53.87 (±38.8) months, with a maximum duration of 153 months. We found a significant improvement in UCVA , BCVA , keratometry and refraction during the follow up period. On correlation analysis, a strong negative significant correlation was found between duration since surgery and each of UCVA (p= 0.008, r= -0.409) and axis of astigmatism (p= 0.008, r= -0.432). The pattern of UCVA improvement and duration since surgery showed an initial improvement peaking at 29 months, followed by a decrease in visual acuity thereafter. At the latest follow up for patients with more than 100 months of follow up (12 eyes), UCVA returned to baseline.

Our long follow up on ISCRS showed a regression in the initial improvement of visual acuity. Considering the relatively young age of populations undergoing such an intervention, patients should be informed that ISCRS impact on visual acuity may regress after few years of implantation.