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D. Gatinel, D. Luce; Corneal Hysteresis and Waveform Analysis in the Normal Fellow Eye of Patients With Newly Diagnosed Keratoconus. Invest. Ophthalmol. Vis. Sci. 2009;50(13):1750.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the corneal hysteresis (CH) and corneal resistance factor (CRF) between normal eyes and the fellow eyes with normal anterior topography of patients with unilateral keratoconus (KC)
All eyes underwent Ocular Response Analyzer (ORA) measurements. Group I included 26 eyes of 26 patients that were classified "Normal" using specular corneal topography and the Nidek Corneal Navigator Classifier, as the contralateral eye was classified "KC". Group II included age and pachymetry-matched 259 normal eyes from 259 patients. The CH, CRF were analyzed and compared between the two Groups. Waveform numerical scores (WS) derived from 24 parameters of the ORA corneal deformation signals were assigned by a neural network.
Compared to eyes in Group II, eyes in Group I had reduced CH (9.11 ± 1.48 vs 10.41 ± 1.23 mmHg, p<0.01) and CRF (8.76 ± 1.79 vs 10.15 ± 1.41 mmHg, p<0.01). Group I and II were significantly separated using WS and and neural network analysis, p<0.01)
These findings suggests that corneal rigidity is impaired before topography detection in the earliest subclinical stage of KC. Waveform numerical scores and neural network analysis of ORA signals could provide an index for the detection of the earliest forms of keratoconus.
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