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

Abstract

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.

Conflict of interest statement

Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that: (1) DRA, JRE, MS and NMR have instrument support from Reichert, Inc. for the submitted work; (2) NMR is a consultant to Allergan and Alcon; and (3) the authors have no non-financial interests that may be relevant to the submitted work.

Figures

Figure 1

Baseline and follow-up intraocular pressure (IOP). A scatter plot illustrates the relationship between baseline IOP and follow-up IOP for each patient initiated on PGA therapy; the line y=x is superimposed to illustrate the relationship between pre- and post-treatment IOP for each patient.

Figure 2

Intraocular pressure (IOP) reduction as a function of corneal hysteresis (CH). A scatter plot illustrates the relationship between baseline corneal hysteresis (CH) and the change in IOP following initiation of prostaglandin analogue (PGA) therapy; the best-fit line is shown (r=0.5).