Screening of Keratoconus Using Autokeratometer and Keratometer Keratoconus Index.

Takashi Kojima,Tomoya Nishida,Naoki Isogai,Tomoaki Nakamura,Kazuo Ichikawa

doi:10.3390/diagnostics11112120

Takashi Kojima, Tomoya Nishida + Show 3 more

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https://doi.org/10.3390/diagnostics11112120

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Abstract

The keratometer keratoconus index (KKI) is a diagnostic index for the risk of keratoconus calculated from autokeratometer test values. We partially modified the KKI equation and assessed it without limiting the target age and severity of keratoconus. This retrospective study included 179 eyes of 99 patients with keratoconus and 468 eyes from 235 normal controls. In the modified KKI, oblique astigmatism or against-the-rule astigmatism was defined as ≥1D astigmatism. KKI diagnostic power was analyzed in subgroups of <50 and ≥50-year-old patients, and at different keratoconus stages. Although the sensitivity of modified KKI was comparable with that of original KKI (92.7% vs. 95.5%), modified KKI specificity was significantly higher (79.7% vs. 68.6%) (p = 0.0001). Using the modified KKI, sensitivity reached 100% (4/4) and specificity, 63.5% (33/52), in ≥50-year-old patients, while overall sensitivity in keratoconus ≥stage 2 was 100% (30/30). In conclusion, the modified KKI proved to be effective in keratoconus screening at all stages. However, it should be noted that false-positive frequency is higher in ≥50-year-old patients.

Highlights

Etiology of keratoconus is unknown, eye rubbing has been reported to be a risk factor for keratoconus development [1–3]. It causes a decrease in spectacle-corrected visual acuity due to an increase in irregular corneal astigmatism
We reported a method to assess the risk of keratoconus with an autokeratometer, which is available in most institutions [27]
Steep K and flat K were significantly higher in the keratoconus group than in the control group

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Keratoconus is a corneal ectatic disease that often occurs between 10–20 years of age. Etiology of keratoconus is unknown, eye rubbing has been reported to be a risk factor for keratoconus development [1–3]. It causes a decrease in spectacle-corrected visual acuity due to an increase in irregular corneal astigmatism. It often requires rigid gas permeable (RGP) contact lenses for refractive correction, and in more severe cases, corneal transplantation

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