Comparison of Intrastromal Corneal Ring Segment Arc 340° Implanted in Eyes With Central Keratoconus Through Tunnel and Pocket
To analyze and compare visual acuity and keratometric parameters of two group of patients with central keratoconus submitted to intrastromal corneal ring segment (ICRS) arc 340 ° implantation.
This prospective study intended to enroll 40 eyes with central keratoconus with the following inclusion criteria: steep meridian until 60 D and thinnest point pachymetry > 400mm. Patients were randomly distributed in two groups: Group A: rings implanted in a stromal tunnel; Group B: rings implanted in a stromal pocket. The visual acuity were measured with ETDRS chart and converted to LogMAR. Keratometric parameters were obtained from a scheimplfug images based tomography (Pentacam HR - Oculus). Patients were evaluated preoperatively, and after 7 days and 1, 3, 6 and 12 months of surgery.
Up to date, 12 eyes of 12 patients were enrolled for the study. The mean follow-up period was 4.1 (3 to 12 months). Mean preoperative K max was 58.99 D (range 47.60 to 67.40); mean corneal preoperative astigmatism was -4.65 D (range -2.40 to -10.70); mean preoperative refractional astigmatism -4.88 D (range -3.50 to -8.00); preoperative mean uncorrected visual acuity (UCVA) was 1.06 and best corrected visual acuity (BCVA), 0.44 (LogMAR) at 3 months post operatory. When comparing differences between the groups, no statistical difference was observed in changes of UCVA, BCVA, K max and pachymetry.
The 340 arc intrastromal corneal ring proved to flat corneal curvature, minimize corneal astigmatism and enhance UCVA and BCVA in eyes with central keratoconus. Also, this study showed no postop clinical difference concerning the implantation technique.