Incidence of keratoconus in subjects with vernal keratoconjunctivitis:: A videokeratographic study

To detect the incidence of keratoconus by videokeratography in patients with vernal keratoconjunctivitis (VKC) and to evaluate the clinical characteristics of VKC associated with keratoconus. A prospective, cross-sectional (prevalence) study. Eighty-two consecutive subjects with the diagnosis of VKC. Both eyes of VKC subjects were investigated by videokeratography in comparison with slit-lamp biomicroscopy and keratometry. To detect keratoconus, corneal topography maps were examined with modified Robinowitz-McDonnell test. In this test, maps with central corneal power greater than 47.2 diopters and/or the inferosuperior asymmetry value greater than 1.4 were considered to have a keratoconus pattern. The findings of VKC were also recorded. The distribution of clinical forms of VKC were as follows: 46.34% mixed, 43.90% palpebral, and 9.76% limbal types. Twenty-six (31.7%) of 82 subjects had complications with kerotopathy such as pseudogerontoxon, punctate keratitis, and shield ulcer. Forty-four eyes (26.8%) were detected as keratoconus by quantitative evaluation of videokeratography maps, 14 eyes (8.5%) by biomicroscopy, and 30 eyes (18.3%) by keratometry. The increased incidence of keratoconus was associated with male gender, long-standing disease, mixed and palpebral forms, and advanced corneal lesions. The higher incidence of keratoconus in our study compared with the previous reports may result from early detection of mild keratoconus by interpretation of color-coded videokeratographic maps with a sensitive quantitative method.