Study Of Earlier Diagnosis And Rigid Gas Permable Contact Lenses Correction In Keratoconus

Objective:Keratoconus was a kind of rarely occur corneal ectasia disease in patients who were juveniles. It was a difficult problem on the optical correction, treatment and control for keratoconus patients. We studied the index of corneal topography to instruct the earlier diagnosis and to guide the RGPCL choice and fitting. All kinds of RGPCL were observed on both correction effect and visual quality.Meathod:In part one, 212(340 eyes) keratoconus patients and 200(400eyes) age-matched normal controls were detectedusing TMS Ⅳ topographer. The index contains SimK1, SimK2,SAI, SRI, CEI, I-S, ΔK, DSI, OSI, CSI, KPI, KCI and KSI.F test, SNK-q test and mutifactor regression were analysed.In part two, 135(259 eyes) keratoconus patients were fitted with 4 kind RGPCL according to the refractive states, corneal surface modality and fitting state. Patients wereexamined periodically on fitting state, VA, K value, astigmatism, corneal topography within 2 years. Paired t test were analysed.In part three, 27(54 eyes) keratoconus patients were divided into three groups. Light 30eyes, moderate 13 eyes and severe 11 eyes were fitted with spherical and special designed Comfort kone lens. Corneal topography, subjective wavefront aberration and contrast sensitive were detected before and after RGPCL wearing within 30 days. Paired t test were analysed.Results:1. Corneal surface morphology in normal eyes was round, oval, symmetry tie and asymmetry tie. While upper corneal curve in sub-clincal patients similar to normal, there were nipple changed in the lower part, especially in lower temperal. 48.6% were asymmetry tie. Corneal steepen in local area as nipple, oval, global, unregular in clinical patients.2. 1 There were significant change between sub-clincal patients clinical patients and normal in corneal topography index except CEI (p<0.001) .2.2 The maximum steep points were not located on corneal center, sub-clincal patients 47% and clinical patients 47%. 104 eyes lower temperal, 35 eyes right down, 45 lower nasal. There were significant changes between allgroups on AK ( p <0. 001) .2.3 There were significant changes between sub-clincal patients, clinical patients and normal in corneal topography attached keratoconus screening index KPI,KCI and KSI (p <0.001) .3. Spherical, asphrical, ROSE-K and Piggyback lens were fitted for keratoconus patients. It showed the corrective VA was significant improved after RGPCL wearing in all groups, sepecial in moderate and severe patients. The corneal K value flattened with corneal astigmatism decrease. Corrective VA was stable with 2 years.4. There was no serious eyes reaction except 17 eyes with mild cornal staining.5. Wavefront aberration increased with disease processing in clinical patients (p<0.001) .6. Wavefront aberration decreased with RGPCL wearing (j?< 0.001) . The most decrease occured at 3 order RMS ( p< 0. 001 ) .7. With RGPCL wearing, Contrast sensitivity curve (light on and light off) were significantly higher than that with SP in whole range of frequency, especially in middle and high frequency (i><0.05, i?< 0.001) .Conclusion:1. Corneal topography index were valuable indifferentiate sub-clinical patients from normal control. The keratoconus screening software was more important. It was easy to make diagnosis union with other regular exams in sub-clinical patients diagnosis.2. For the light, moderate and severity keratoconus patients, wearing different design RGPCL could provide sufficient corrective effect. It was successful and safe for long period wearing.3. RGPCL showed some Orthokeratologic effect in keratoconus patients. The corneal curve flattened and astigmatism decreased. Piggyback lens could improve RGPCL stability and prevent corneal scar forming while acute corneal edema occured.4. The significant improvement on corneal topography, contrast sensitivity, Wavefront aberration results of keratoconus patients identified the corneal regularity and visual quality improvement.