ABSTRACT

Pur­po­se:

To determine and compare the corneal biomechanical properties in keratoconus patients using rigid gas permeable contact lenses and keratoconus patients who do not use contact lenses.

Ma­te­ri­al and Met­hod:

The study consisted of 70 healthy controls (Group A), 27 ketatoconus subjects who do not use contact lens (Group B) and 36 rigid gas permeable contact lens using keratoconic patients (Group C). Corneal viscoelastic parameters were measured with an Ocular response analyzer (ORA). Central corneal thickness was measured with an ultrasonic pachymeter. The differences in ORA parameters between the groups were compared.

Re­sults:

The mean corneal hysteresis (CH) in Groups A, B, and C were 10.3±1.5 mm Hg, 7.8±1.4 mm Hg, and 7.4±1.2 mm Hg, respectively. The differences in mean CH between Group A and the other two groups were statistically significant (p<0.01 for both comparisons), but no statistically significant difference was found between groups B and C in terms of mean CH (p=0.61). The mean corneal resistance factor (CRF) was 10.7±1.9 in Group A compared with 6.6±1.6 in Group B and 6.1±1.5 in Group C. The differences in mean CRF between Group A and the other two groups were statistically significant (p<0.01 for both comparisons). There was no significant difference in CRF between the keratoconus eyes with or without rigid gas permeable contact lens usage (p=0.57).

Dis­cus­si­on:

Our results suggest that ORA-generated parameters may be different in subjects with keratoconus. Corneal biomechanical parameters did not demonstrate a clear trend of change with rigid gas permeable contact lens usage. (Turk J Ophthalmol 2012; 42: 197-201)