Corneal Biomechanical Properties of Keratoconic Eyes Following Penetrating Keratoplasty

Corneal biomechanics and cornea assessment in Fuchs heterochromic iridocyclitis patients

Aim: To evaluate cornea and corneal biomechanical properties of patients with Fuchs heterochromic iridocylitis. Materials and Methods: Fourteen FHI positive eyes (Group 1) and the contralateral healthy eyes (Group 2) were included. All patients underwent a detailed ophthalmic examination was performed. Also, Ocular Response Analyzer was used to detect corneal biomechanical properties, and specular microscopic evaluation for corneal endothelial cells count was performed. Results: The mean best corrected visual acuity and intraocular pressure were statistically similar. (p values were 0.077 and 0.557, respectively). Corneal biomechanical properties including corneal hysteresis, corneal resistance factor, IOPcc and IOPg were not statistically significant. (p values were 0.521, 0.817, 0.980 and 0.980, respectively). Mean central corneal thickness in Group 1 and 2 were 555.57±42.95 (467-626), 556.5±37.04 (480-623) micrometer, respectively. The difference was not statistically significant (p=0.959). Mean corneal endothelial cell density of Group 1 and Group 2 were 2313±420.22 (1271-2717) and 2404.42±326.75 (1566-2834) cells/mm2, respectively. The difference was not statistically significant (p=0.626). Conclusion: Conflicting with the literature, no differences were detected in corneal biomechanical properties, central corneal thickness and corneal endothelial cell density in Fuchs Heterochromic Iridocyclitis positive eyes. However, more studies with increasing number of patients are still needed.

Corneal biomechanics and intraocular pressure assessment after penetrating keratoplasty for non keratoconic patients, long term results

Background

To evaluate corneal biomechanical properties by the Ocular Response Analyzer (ORA) in non keratoconic patients underwent penetrating keratoplasty (PK).

Methods

Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann- correlated intraocular pressure (IOPg), cornea-compensated IOP (IOPcc) using the ORA, and central graft thickness (CGT) were measured in 30 eyes at least two years after penetrating keratoplasty for non keratoconic indications. IOP using the Goldmann applanation tonometer (GAT) was also obtained after compensation for graft thickness and astigmatism.

Results

The mean age of patients was 33.1 ± 10.13 years; indications for PK were herpetic corneal scar (53.3%), corneal stromal dystrophy (23.3%), traumatic corneal opacity (10%), chemical corneal opacity (6.7%), and Fuchs endothelial dystrophy (6.7%). Mean CH and CRF were 8.52 ± 1.81 mmHg, and 8.56 ± 1.59 mmHg, respectively. Mean CGT was 532.43 ± 30 μm. Mean IOP GAT, IOPg, and IOPcc were 11.88 ± 3.66, 14.64 ± 4.08, and 17.27 ± 4.60 mmHg, respectively (P < 0.001). No significant association was found between CGT and IOP readings obtained using either the ORA or GAT. There were significant negative association between CH with both IOP GAT and IOPcc, while CRF had significant positive association with IOPg.

Conclusion

After penetrating keratoplasty for non keratoconic patients, graft biomechanics does not return to average values even 2 years after the operation; moreover, intraocular pressure measurement with ORA gives higher values than thickness compensated GAT.