Measure of keratoconus progression in patients with vernal keratoconjunctivitis using scanning slit topography

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To document topographic changes using Orbscan in patients with keratoconus and vernal keratoconjunctivitis over 1 year. Retrospective analysis of clinical and Orbscan data of 22 eyes of 11 patients with keratoconus and VKC with follow up over 1 year period was done. The parameters studied included patients demographics, clinical features, visual acuity, refraction and Orbscan IIz. The changes in various Orbscan parameters were studied over the 1-year period. Mean age was 14±4.1 years. 20 eyes had clinical keratoconus, while 2 had forme fruste keratoconus. 8 eyes of 22 showed evident progression (>1 diopter change in mean simulated (sim) K over 12 months). There was no significant difference in the visual acuity or clinical features over follow up. In patients with progression, statistically significant change (p<0.05) was found in posterior float curvature, sim K astigmatism and maximum astigmatism. Rest of the parameters did not show significant change. Among the patients without evident progression, none of the parameters showed significant change. On comparing the patients with clinical signs of keratoconus with those with only topographic signs of keratoconus, there was no difference between the two groups with respect to the rate of progression of keratoconus. Patients with both mixed type and pure palpebral type of VKC had comparable Orbscan parameters at baseline and 1 year follow up and similar progression rate of keratoconus. Serial topographic analysis provides numerical information about various corneal parameters in patients with vernal keratoconjunctivitis and keratoconus.