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Claude J. Giasson, Fanny Ancian, Daniel Brazeau; Comparative Esthesiometry Between Keratoconic And Normal Subjects. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1089.
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To quantify the loss of corneal sensitivity observed in keratoconus; to examine if the most advanced keratoconic eye has the largest loss in sensitivity.
This study was done on 15 normal subjects and 15 subjects with keratoconus. The length of filament to elicit sensation was used to determine the threshold sensitivity with the Cochet Bonnet esthesiometer for both eyes in both groups of subjects. The cornea of subjects was also examined by slit lamp microscopy and Orbscan topography. The side with the most advanced keratoconus was the one with the largest apical curvature on the topograph. Differences in corneal sensitivity between the right and left eyes were tested for significance with paired t-tests in normal subjects, and then between the most advanced and least advanced eyes of subjects with keratoconus. Differences in sensitivity between keratoconic and control subjects were tested for significance with an independent t test. The association between the threshold sensitivity and apical curvature was analyzed in the most advanced eyes of keratoconic subjects with a Pearson linear correlation.
There was no difference in sensitivity between the right and left eyes (5.3 +/- 0.9 and 5.5 +/- 0.9 mm) of control subjects. The threshold sensitivity was lower (3.7 +/- 1.5) in the most advanced eye compared to the least advanced one (4.2 +/- 1.1), but the difference was not statistically significant (p=0.11). The difference in sensitivity between keratoconic subjects (3.7 +/- 1.5) and normal controls (5.3 +/- 0.9) was statistically significant with an independent t test (p = 0.002). The correlation between sensitivity and apical curvature in the most advanced eye was not significant (p=0.13). Nine subjects had a lowered sensitivity in the most advanced cornea, 4 subjects had the lowest sensitivity in the least advanced cornea.
There is a loss in corneal sensitivity in subjects with keratoconus compared to healthy controls. In subjects with keratoconus, we could not demonstrate an association between the loss in sensitivity and the apical curvature of the most advanced eye. However, insufficient power due to the small sample size may be responsible for this absence of a significant association.
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