Visual and corneal morphology changes after a double arc intracorneal ring segment (ICRS) implant for keratoconus treatment

Session Details

Session Title: Photoablation, Cross-Linking and Intracorneal Ring Segment

Session Date/Time: Monday 07/09/2015 | 08:00-10:30

Paper Time: 08:54

Venue: Room 16

First Author: : H.Melo BRAZIL

Co Author(s): :    C. Oliveira   E. Nakano   P. Caddah   M. Machado   J. Filho   C. Costa     

Abstract Details

Purpose:

To verify changes in visual acuity, corneal astigmatism and corneal K max after the implantation of a double arc ICRS.

Setting:

This multicenter, prospective, randomized study is being conducted at the Federal University of São Paulo (UNIFESP) and at the Hospital Oftalmológico de Brasília (HOB).

Methods:

Forty eyes of selected patients were divided into groups A (K max up to 60D) and B (K max from 61 to 75D). Eyes were also divided into two sub-groups according to the degree of corneal astigmatism. Corneas with topographic astigmatism up to 5D received a 330 degrees segment (incision at 12 o'clock position); and those with higher amounts of astigmatism received two 160 degrees segments (incision on the superior side of the steepest corneal meridian). The femtolaser created a tunnel at 75% depth at 5mm diameter. Keratometric assessment was performed with OPDScan III.

Results:

To date, 28 eyes completed three months of follow-up. Best corrected visual acuity (BCVA) changed from 0.46 to 0.30 and 0.27 (logMAR) preop, 30 days and 3 months, respectively. Uncorrected visual acuity (UCVA) varied from 0.86 to 0.63, 0.62 and 0.67; K max changed from 59.55D (group A 55.83D; group B 63.84D) to 57.94D (A 53.87: B 63.02D); 57.58D (A 53.95: B 62.20D); and 58.88D (A 54.99; B 64.32D); Mean corneal astigmatism varied from 5.5D (in eyes with a 160/160 implant the astigmatism was 6.9D, whereas those with 330 implant the astigmatism was 3.5D) to 2,7D (3.0: 2.3D); 2.5D (2.9: 1.9D) and 2.5D (2.58: 2.5D) from preop to 7 days, 30 days and 3 months postoperatively.

Conclusions:

The expected effects of the double arc ICRS are central flattening, corneal asphericity modulation and centration, and corneal astigmatism management as its design provides a 45D curvature profile to the ICRS. The results to date have been showing a significant decrease in astigmatism degree, especially in corneas with higher toricity. K max, however, has not decreased as expected. Despite of the increase of UCVA, BCVA showed a better enhancement postoperatively due to the residual spheric component of the refraction. Further analysis was proposed with the intention to get answers not yet found in the current study.

Financial Interest:

NONE