In vivo keratometric changes in rabbit eye induced by topical 17β-estradiol

Abstract

Purpose : <div style="direction: ltr;">In vitro, 17β-estradiol (E2) has been shown to modulate the bio-mechanical properties of the cornea, causing a reduced stiffness of the tissue. In light of these reports we hypothesized that topical E2 might affect the refractive properties of the cornea inducing a myopic shift in-vivo.</div>

Methods : <div style="direction: ltr;">A dozen of New Zealand white rabbits aged 16 weeks were used.. The rabbits were randomly divided equally to either the treatment group receiving 1.5% (w/v) E2 eye drops or control group receiving vehicle only. Both groups were given drops (50 µL) to the right eye twice daily 12 hrs apart for 35 days. Keratometry and refraction were evaluated at baseline and on a weekly basis using Righton Retinomax K-plus 3. Pachymetry and intraocular pressure (IOP) were evaluated as well.</div>

Results : <div style="direction: ltr;">No significant differences were observed between the two groups at baseline. As expected from previous studies (Riau et al. 2012), both groups displayed corneal flattening and hyperopic shift in keratometry, however the change-rate was slower in the treatment group (Figure 1). Repeated measure analysis adjusted for baseline weight and pachymetry revealed a significant difference in keratometry between groups (P = 0.034) with mean higher keratometry values in the treatment group by up to 0.6 diopters. The difference between the two groups diminished and became statistically insignificant after stopping treatment. No significant changes were observed in terms of IOP and pachymetry throughout the study period. None of the rabbits showed signs of inflammation or any other side-effect in either group. </div>

Conclusions : <div style="direction: ltr;"><div style="direction: ltr;">1.5 % (w/v) E2 eye drops applied BID induced a myopic shift by affecting keratometry in the rabbit eye. Further investigation to the physiology of this change is needed.</div></div>

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.