Long term efficacy of rigid gas permeable contact lens wearing in keratoconus

Objective To observe the 3 years or more effects on optical correction,refraction,and orthokeratology with rigid gas permeable contact lens(RGPCL) wearing in patients with keratoconus.Design Retrospective case series.Participant 73 keratoconus patients(136 eyes) fitted with RGPCL.Methods Patients wearing RGPCL for 3 years or more in Peking University Optometry Ophthalmology Center were observed.Correct visual acuity was determined before and at 1,2 and 3 years of lens wearing,and the refractive power,corneal curvature,corneal astigmatism and corneal morphological changes were measured with auto-refractomer/keratometer and keratoconus screening analysis system of computer-assisted corneal topography at the same time.The changes of base curve and RGPCL power were also compared.All patients were divided into mild keratoconus group(Group A),moderate and severe keratoconus group (Group B).Main Outcome Measures Visual acuity,refractive power,base curve of RGPCL,corneal topography parameters.Results The patients wore RGPCL for 49.3±15.3 months(36-76 months).At the initial visit,uncorrected visual acuity(UVA) was 3.76±0.45, corrected visual acuity with spectacles(SPVA) was 4.57±0.53,and with RGPCL(RGPVA) was 4.89±0.14.RGPVA was improved significantly (F=171.994,P=0.000).RGPVA at last visit(4.95±0.11) was better than that at initial visit(t=-6.733,P=0.000),which was more significant in group B than that in group A.The rate for RGPVA more than 0.8 at the initial,1 year,2 years and 3 years of lens wearing was 85.13%,86.76%,85.60%and 84.62%respectively.At the initial visit and last visit,the myopia diopters and the corneal astigmatism were 7.13±4.01D vs.6.23±3.42D(P=0.014) and 6.23±3.24D vs.4.42±2.34D(P=0.000) respectively.The RGPCL base curve and lens power were 7.38±0.50 mm vs.7.54±0.42 mm(P=0.000),and -6.22±3.59 D vs.-5.33±3.09 D(P=0.000) respectively. The changes of power and base curve of lens in group B were more significant than that in group A.The decrease of 9 corneal topography parameters between initial visit and last visit was significant statistically(all P0.05) except SAI,IAI and AA.Conclusions The patients with keratoconus can obtain much better and stable visual acuity and remarkable orthokeratology effect for a long-term RGPCL wearing in scientific way.Myopia and astigmatism power can be decreased significantly.The results show the keratoconus control is effi-cient.