Posters

210º intracorneal ring segments (ICRS) in keratoconus: refractive, aberrometric and geometric results – a comparison between 5 and 6 mm optical zones

Poster Details

First Author: N.Alejandre Alba SPAIN

Co Author(s):    P. Perez-Merino   G. Velarde   I. Jimenez-Alfaro   S. Marcos           

Abstract Details

Purpose:

To describe the effects induce in the cornea by implanting one 210º ICRS in keratocnous patients using optic design tools allowing a customized analysis. To compare geometry (changes by axis incluiding asphericity), corneal aberrations, visual quality metrics (Visual Strehl Ratio) and clinical variables betwen 5 and 6 mm optical zone ICRS

Setting:

Universitary hospital

Methods:

A prospective observational study was conducted in 38 patients. A complete ophthalmic evaluation incluiding refraction was performed before and three months after surgery. Also Sheimpflug images were obtained using Pentacam at the same visits. Raw elevation points were extracted from Pentacam and a reconstruction of the central 4 mm of the optic zone of the segments was performed using mathlab, then virtual ray tracing with Zemax was performed. Theis allowed the study of all the meridians with diferent bodies of reference, sphericity, corneal aberrations and Visual Strehl Ratio as well as vector analysis of astigmatism. BCVA was also recorded.

Results:

5 mm (24 patients): there was an important flattening in all the meridians (p <0.001). Asphericity remained stable. RMS decreased (41.75%, p <0.001). Coma decreased (39.22 % , p 0.002). Astigmatism decreased (25 %, p 0.014). Visual Strehl Ratio improved (p 0.004). BCVA improved (p <0.001). Refractive SIA was 3.025 ± 2.177 D. 6 mm (14 patients): they produced less flattening (p 0.021) and less reduction of corneal aberrations and Visual Strehl Ratio (p 0.009) without statistically significant improvement in BCVA.

Conclusions:

5 mm 210º ICRS are very effective in flattening the cornea and reducing corneal aberrations in patients with keratoconus and low astigmatism. 6 mm 210º ICRS are much less effective and should be reserve to less severe cases where small effects are desired but avoided if a significant change is intended.

Financial Disclosure:

None