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P.J. Chastang, R. Tabet, M. Duong, O. Prisant, D. Gatinel, T. Hoang-Xuan; Orbscan II in Asymptomatic Family Members of Patients With Keratoconus . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1307.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: to evaluate corneal pattern using Orbscan II device and relationship with EyeSys 2000 data in asymptomatic family members of keratoconic patients. Methods: 27 asymptomatic relatives (54 eyes) of 12 patients with symptomatic keratoconus were evaluated. Two exams were performed in each cases. Main evaluated parameters were simulated keratometry (SimK), central keratometry (Kc),I-S index, Asphericity (Q) using EyeSys 2000, maximal anterior and posterior elevation compared to the best-fit sphere (Eant and Epost), central pachymetry (Pc), thinnest pachymetry (Pth) and irregularity (Irreg5) using Orbscan II. Results: For each parameter, no statistical difference was noted between the two successive exams. Mean values for SimK, Kc, I-S, Q, Eant, Epost, Pc, Pth, Irreg5, were 43.03 +/- 1.43 D, 43.08 +/- 1.42 D, 0.62 +/- 0.46 D, -0.10 +/- 0.14, 0.020 +/- 0.026 mm, 0.028 +/- 0.024 mm, and 1.63 +/- 0.63 D respectively. 21 (39%) eyes presented a I-S value greater than 1.4 D and/or a difference of central K greater than 1D (topographics signs of infraclinic keratoconus). 20 (37%) eyes had a Pth less than 500µm. Only 3 (15%) of these 20 eyes had topographic signs of infra-clinic keratoconus, particularly statistically significant I-S value. Comparison between eyes with Pth less than 500 µm and eyes with Pth geater than 500 µm showed a statistically significant difference only for SimK, Kc, and Pc (p=0.007, p=0.007, and p=0.0001). Conclusions: Orbscan corneal analysis showed frequent thin pachymetry (<500µm) without other topographic abnormalities in this population.
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