JKOS Journal of the Korean Ophthalmological Society J Korean Ophthalmol Soc 0378-6471 2092-9374 The Korean Society for Quality Management 10.3341/jkos.2015.56.7.1006 jkos-56-1006 Original Article Long-Term Effect and Safety of Contact Lenses for Keratoconus LeeJong Heon M.D. 1 ParkYoung Min MD 1 ParkYoung Kee MD PhD 2 LeeJong Su MD PhD 1 LeeJi Eun MD PhD 1 3 Department of Ophthalmology, Pusan National University School of Medicine, Busan, Korea YK Eye Clinic, Seoul, Korea Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea Address reprint requests to Ji Eun Ji MD, PhD Department of Ophthalmology, Pusan National University Yangsan Hospital, #20 Geumo-ro, Mulgeum-eup, Yangsan 626-770, Korea Tel: 82-55-360-2590, Fax: 82-55-360-2161 E-mail: Jiel75@hanmail.net 08 2015 27 8 2015 56 7 1006 1011 19 12 2014 30 01 2015 04 06 2015 Copyright © 2015 Korean Ophthalmological Society 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Purpose:

To evaluate the long-term clinical effect and safety of YK-KC lens® (LucidKorea Ltd., Seoul, Korea) for keratoconus. Methods: In this study we investigated 152 keratoconic eyes fitted with YK-KC lens® and followed up for at least 5 years. We as-sessed retrospectively self-reported patient comfort, best corrected visual acuity, corneal topographic indices before and after contact lens fitting and complications during contact lens wearing.

 Results:

The study included 57 male and 40 female patients with a mean age of 28.6 ± 8.5 years. The mean follow-up was 8.0 ± 2.9 years. Regarding lens comfort, 126 eyes (82.9%) showed self-reported comfort for YK-KC lenses®. The mean best cor-rected visual acuity (log MAR) improved from 0.49 ± 0.42 before lens fitting to 0.19 ± 0.27 after lens wearing, which was statisti-cally significant ( p < 0.001). Based on the keratometric values, after contact lens fitting both Simulated keratometry (Sim K) max and Sim K min tended to be steeper, but these differences were not statistically significant ( p = 0.66 and 0.11, respectively). There were no statistically significant differences between the values before and after fitting with respect to the astigmatic pow-ers ( p = 0.22). Complications observed included punctate or coalesced epithelial corneal staining in 24 eyes (16%), however, persistent full-thickness epithelial defect was not observed.

 Conclusions:

The YK-KC lens® in patients with keratoconus can provide excellent visual improvement and comfort without any significant influence on the progression of keratoconus or corneal complications during a long-term follow-up period.

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Distribution of self-reported assessment of contact lens comfort.

Change in best-corrected visual activity (BCVA) be-tween spectacles and YK-KC lenses®. Points lying above the solid 45° line correspond to eyes with improved vision with YK-KC lenses®.

Distribution of visual acuity when wearing YK-KC lens®, plotted against the base curve radius of the lens. Better visual acuity was achieved when contact lenses with flatter base curve radii were fitted.

Correlations between topographic indices and contact lens base curve radius (BCR). 'r' means Pearson's correlation co-efficient between Sim K min and BCR (A), between average of Sim K and BCR (B), between Sim K max and BCR (C), and a rela-tionship is considered to be statistically significant if p < 0.05. Sim K = simulated keratometry; min = minimum.

The shape and location of the cones

Shape of cones Location of cones Number of eyes (%)
Nipple Center 51 (33.6)
Inferior paracenter 76 (50.0)
Superior paracenter 5 (3.3)
Oval Inferonasal 4 (2.6)
Inferiotemporal 2 (1.3)
Superior 1 (0.7)
Globus Center 13 (8.6)
Inferior 0 (0)