Use of Biomechanical Waveform Analysis to Establish IOP and Biomechanical Properties of Cornea in Adult Myopic Egyptian Patients
Narrative Responses:
Purpose
To determine intraocular pressure and corneal biomechanical properties in myopic subjects in Suez Canal area in Egypt.
Methods
Three hundred and fifty eyes (350) of Myopic patients (n = 179, age: 29.4 ± 8.9 years) with mean refractive errors of spherical equivalent (SE)+ SD was -5.00D+ 2.8D were recruited in this study. All subjects in this population-based study underwent standardized ocular examinations. Metrics of corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), Central corneal thickness (CCT), were measured with the Ocular Response Analyzer (ORA). The ORA also determined the values of intraocular pressure (IOPg) and corneal compensated IOP (IOPcc).
Results
The mean corneal hysteresis was 9.3+1.4. The mean CRF was 9.7+1.6. The mean CCT was 535.1+37.7 µm. The mean IOPg 16.3+3.13mmHg and IOPcc 17.8+2.9 mmHg. The relationship between CH, CRF and CCT; CRF and CH were significant (p < 0.0001). There is a negative correlation between CH and IOPcc, positive correlation between IOPcc and refractive errors. IOPcc measured by ORA is greater than IOPg by 11.2% (p<0.0001). The cut-off point of IOPcc is 19.2mmHg. CH and CRF decreased in aged subjects.
Conclusion
Corneal hysteresis (CH) and corneal resistance factor (CRF) measured by the ORA of myopic Egyptians have a positive but moderate correlation to CCT; the higher the CCT the higher the hysteresis (visco-elasticity) and CRF (elasticity). It may be helpful in the future for long term monitoring of glaucoma.