Biomechanical and Tomographic Analysis of Unilateral Keratoconus

PURPOSE: To evaluate and compare tomographic, clinical, and biomechanical data of patients with unilateral keratoconus and healthy controls. METHODS: Observational, case-control study. Complete clinical eye examination was followed by topographic (ATLAS), tomographic (Pentacam), and biomechanical (Ocular Response Analyzer) evaluation. Cases were sex-and age-matched with healthy individuals for controls. RESULTS: Four patients had unilateral keratoconus, and eight healthy patients served as controls. Central corneal thickness was 508 +/- 16 mu m in the keratoconus group, 531 +/- 12.7 mu m in the fellow eye group, and 528.6 +/- 40.7 mu m in the control group (P > .125, all comparisons). Central keratometry was 43.70 +/- 2.70 diopters (D) in the keratoconus group, 42.84 +/- 1.43 D in the fellow eye group, and 43.81 +/- 1.94 D in the control group (P > .45, all comparisons). Corneal astigmatism was 3.30 +/- 2.24 D in the keratoconus group, 1.38 +/- 1.49 D in the fellow eye group, and 1.34 +/- 1.13 D in the control group (P =. 037 between the keratoconus and control groups; P =. 25 between the keratoconus and fellow eye groups). Corneal hysteresis was 8.13 +/- 2 mmHg in the keratoconus group, 8.96 +/- 0.86 mmHg in the fellow eye group, and 9.89 +/- 1.33 mmHg in the control group (P > .064, all comparisons). Corneal resistance factor was 7.96 +/- 2.43 mmHg in the keratoconus group, 8.92 +/- 1.39 mmHg in the fellow eye group, and 9.90 +/- 2.24 mmHg in the control group (P > .33, all comparisons). CONCLUSIONS: Corneal hysteresis and corneal resistance factor values were not statistically different among the groups; however, a trend for lower values was found for keratoconus and fellow eyes compared to controls. Data should be interpreted with caution because of the small sample. [J Refract Surg. 2010; 26(9): 677-681.] doi:10.3928/1081597X-20091105-04