The relationship between corneal hysteresis and the magnitude of intraocular pressure reduction with topical prostaglandin therapy

AIMS To evaluate corneal hysteresis (CH) and intraocular pressure (IOP) before and after IOP lowering with prostaglandin analogue (PGA) therapy in medication-naïve eyes. METHODS In this retrospective study, we included records from 57 consecutive patients with open angle glaucoma who were initiated on PGA. Patients underwent ocular response analyser measurement with IOP assessment at baseline (untreated) and at follow-up (treated). RESULTS Median follow-up time between IOP measurements was 1.4 (range 0.4-13.5) months. IOP was reduced by 3.2 mm Hg (18.8%) from 17.0 to 13.8 mm Hg (p<0.001). CH increased by 0.5 mm Hg (5.2%) from 9.7 to 10.2 mm Hg (p=0.02). Baseline CH (but not baseline central corneal thickness) was a significant predictor of the magnitude of IOP reduction, with patients in the lowest quartile of CH (mean 7.0 mm Hg) experiencing a 29.0% reduction in IOP while those in the highest CH quartile (mean 11.9 mm Hg) experienced a 7.6% reduction in IOP (p=0.006). A multivariate analysis controlling for baseline IOP demonstrated that baseline CH independently predicted the magnitude of IOP reduction with PGA therapy in both per cent (ß=3.5, p=0.01) and absolute (ß=0.6, p=0.02) terms. CONCLUSION Although CH is influenced by IOP, baseline CH is independently associated with the magnitude of IOP reduction with PGA therapy.