STUDY OF CORNEAL HYSTERESIS AND CORNEAL RESISTANCE FACTOR IN PELLUCID MARGINAL CORNEAL DEGENERATION BY OCULAR RESPONSE ANALYZER

Purpose: The present research aimed to study the corneal hysteresis (CH) and corneal resistance factor (CRF) in Pellucid Marginal Corneal Degeneration (PMCD) by means of Ocular Response Analyzer (ORA) Methods: This retrospective observational study performed based on patients’ medical records from January 2013 to October 2015. A total of 102 eyes from 63 patients with age range of 20 to 50 years were included. Inclusion criteria for this study was diagnosis of PMCD based on clinical and paraclinical evaluations. Exclusion criteria for this study consisted of any other corneal disease, severe dry eye, glaucoma, using any ocular medication, pregnancy or nursing, systemic disease, history of previous eye surgery, older than 50 years and eyes suspect to another corneal ectasia. The data of CH, CRF and other outcomes of ORA were obtained and data analysis was performed using SPSS software for descriptive and analytical statistical methods. Results: According to the outcomes of ORA in our study, CH, CRF, Goldmann-correlated intraocular pressure (IOPG) and corneal-compensated intraocular pressure (IOPcc) were (mean ± SD) 9.18±1.47, 8.48±1.72, 12.38±3.42 and 14.58±3.08 respectively. There is no statistically significant difference between male and female for CH (P=0.12), IOPG (P=0.07) and IOPcc (P=0.37) except for CRF (P=0.01). Conclusion: These data provide normative values for PMCD measured using the ORA. Corneal biomechanical outcomes of ORA include CH and CRF in PMCD may be employed for diagnosis and treatment of PMCD.