Abstract
Purpose::
To evaluate changes in Corneal Hysteresis (CH) and Corneal Resistance Factor (CRF) in eyes with herpetic stromal scarring using the Reichert Ocular Response Analyzer (ORA). The ORA is a new technology which measures biomechanical properties of the cornea by means of a dynamic bi-directional applanation process. CH is stated to be a new independent measure of corneal tissue property. CRF, which is calculated from the CH, is stated to be a measure of the "resistance" of the cornea dependent on its structural integrity.
Methods::
Retrospective review identified 11 patients (5 men, 6 women) with monocular herpetic stromal scarring who had CH and CRF measurements taken in both the involved and normal eye using the ORA . The involved eyes were further subdivided by central versus peripheral scarring and the presence or absence of corneal neovascularization. Statistical analysis was performed on the collected data.
Results::
CH was significantly reduced in the eyes with herpetic stromal scarring (Average CH = 8.7, Standard Deviation = 2.0) compared with the normal eyes (Avg CH = 11.0, SD = 2.2). CRF was also significantly reduced in the involved eyes (Avg CRF 8.5, SD = 2.0) compared with the normal eyes (Avg CRF = 10.85, SD = 2.17). Eyes with central scarring demonstrated a significantly greater reduction in CH (Avg 21.6% reduction) and CRF (Avg 23.2% reduction) than eyes with peripheral scarring (Avg CH reduction = 11.6%, Avg CRF reduction 11.1%). Eyes with scaring and neovascularization did not show a significant difference in CH and CRF measurements than with scarring without neovascularization.
Conclusions::
Eyes with herpetic stromal scarring demonstrate a significant reduction in both CH and CRF. Central scaring leads to a larger reduction in CH and CRF than peripheral scarring. Neovascularization did not affect CH or CRF measurements in eyes with scarring.
Keywords: cornea: clinical science • cornea: stroma and keratocytes