Corneal Biomechanics In Post-Keratoplasty Eyes

Mahesh Kumar

PURPOSE: To evaluate corneal biomechanical properties in eyes that have undergone penetrating keratoplasty (PK) using the ocular response analyzer (ORA).

METHODS: Prospective case-control observational study of normal eyes and postkeratoplasty eyes of Asian–Indian patients. Data recorded included corneal hysteresis(CH), corneal resistance factor(CRF), Goldmann-correlated intraocular pressure(IOPg), and cornea-compensated intraocular pressure(IOPcc), using the Ocular response analyzer, corneal topography using videokeratography (VKG) and central corneal thickness (CCT) using ultrasonic pachymetry.

RESULTS: 100 normal eyes of 64 patients and 54 postkeratoplasty eyes with a mean postoperative period of 19.33 ± 6.42 months were included in the study. Mean postkeratoplasty astigmatism was 8.73±5.61. The CH was 8.340 ± 1.85 mmHg in post-pk eyes and 9.864±1.29 mmHg in the normal eyes (p=0.0001). The CRF was 8.846 ± 2.39 and 9.385±1.39 mmHg in post-pk and normal eyes respectively (p=0.0793). The IOPcc's were 18.625 ± 7.97 and 14.954±3.50 mmHg in post pk and control eyes respectively. IOPg's were 15.996 ± 8.09 and 13.731±3.22 mmHg (p=0.0148) in post pk and control eyes respectively. CH and CRF did not correlate with postkeratoplasty astigmatism (p = 0.311 & 0.181 respectively) while a significant correlation was observed with IOPg (p = 0.005) & IOPcc (p <0.001). The mean IOPcc (18.47 ± 8.84 mmHg) was significantly higher in the PK group than in the control group (14.44 ± 2.85 mmHg) (p < 0.0001).

CONCLUSIONS: Biomechanical profiles were observed to be significantly decreased in post keratoplasty eyes, which showed significant correlation with raised IOP. Corneal astigmatism does not correlate with these profiles.