To evaluate the efficacy, safety of rigid gas permeable contact lens (RGPCL) wearing for over 5 years in different degrees of keratoconus eyes.

A retrospective case study was performed.The clinical data of 217 eyes with different degree of keratoconus from 126 keratoconus patients who fitted with RGPCL in Beijing Tongren Hospital from 2000—2010 over 5 years were analyzed.The eyes were divided into mild keratoconus group (Ks≤45.0 D), moderate keratoconus group (45.0 D< Ks < 52.0 D) and severe keratoconus group (Ks≥52.0 D) according to the severity.Uncorrected visual acuity (UCVA, LogMAR), spectacle corrected visual acuity (SCVA) and RGP corrected visual acuity (RGPVA) was examined before RGPCL wearing and the end of following-up after RGPCL wearing.The refraction, corneal curvature, corneal astigmatism were measured with auto-refractomer/ keratometer and keratoconus screening analysis system of computer-assisted corneal topography.Comparisons of the changes of corrected visual acuity and corneal parameters were assessed.

The RGPVA was 0.09±0.17, 0.05±0.07 and 0.07±0.07 in the mild, moderate and severe keratoconus group, respectively, showing a significant difference among the three groups (F=0.522, P=0.594); The ΔKs was (2.25±5.42), (0.26±3.44) and (-4.52±3.44)D, and ΔKf was (2.06±4.98), (1.02±3.41) and (-2.03±5.05)D, and the change value of corneal astigmatism was (0.19±2.87), (-0.78±2.84) and (-2.44±3.77)D in the mild, moderate and severe keratoconus group(all at P<0.05), respectively, with the minimum amount of change in the severe keratoconus group.The variation of differential sector index (ΔDSI) was -0.33±1.64, 0.14±3.01 and -2.11±4.28; the variation of center/surround index (ΔCSI) was -0.41±1.07, 0.03±2.22 and -2.49±4.15; the variation of standard deviation of power (ΔSDP) was -0.43±0.64, -0.02±0.89 and -1.67±1.68; the variation of keratoconus prediction index (ΔKPI) was 0.00±0.07, 0.03±0.09 and -0.05±0.11 in the mild, moderate and severe keratoconus group, respectively, and the reduced amount in above parameters was much more in the severe keratoconus group than that in the mild and moderate keratoconus group (all at P<0.01). Mild conjunctivitis and corneal affection occurred in 12 eyes (5.5%) during the follow-up.

Long-term wearing RGPCL can improve the visual acuity and slow the tendency of corneal curvature increase in keratoconus eyes, and this procedure is safe and effective for the correction of different degree of keratoconus.

Keratoconus; Rigid gas permeable contact lens; Corneal curvature