The Effect Of Topical Phenylephrine On Optical Biometry And Corneal Topography

Examine the effect of phenylephrine on biometry measurements. Mild- moderate ptosis may affect corneal curvature values. Phenylephrine, an alpha-adrenergic agonist, enlarges the lid aperture by stimulation of the Müller muscle. As temporary upper lid retractor, phenylephrine may enhance accuracy of corneal measurements and IOL power calculations.

The study was conducted at Kaplan Medical center, Ophthalmology outpatient clinic. 

Fifty patients planned for cataract surgery were enrolled. They underwent complete eye examination, best corrected visual acuity and refraction. Optical biometry measurements were performed, and the external eye was photographed using the IOL Master 700 (Zeiss, Germany). Corneal topography was performed using Pentacam (Oculus, Germany). This entire pre-operative evaluation was repeated 10 minutes after topical application of phenylephrine 10%.

Applying phenylephrine led to a statistically significant increase in axial length, with an average increase of 0.003mm (P < 0.05). However, no significant changes were observed in other biometric measurements (K1, K2, ACD, LT, WTW) assessed by the IOL Master 700 or corneal topography parameters (K1, K2, K-Max) measured by the Pentacam.

Our findings demonstrate that topical phenylephrine does not significantly alter biometry measurements or corneal topography, in the general population undergoing pre-operative assessments.

While the change in the AL was statistically significant, the magnitude of this change was small and unlikely to have any clinical impact on intraocular lens (IOL) power selection.

This suggests that, for patients with mild-moderate ptosis and challenges acquiring these measurements due to eyelid position, using phenylephrine as a temporary upper lid retractor may be a valid option. Further research is necessary to evaluate Phenylephrine's effect in specific ptosis severity subgroups.