The Combined Effect of Tropicamide and Phenylephrine on Corneal Astigmatism Axis

ABSTRACT

Purpose

To analyze astigmatism axis changes after tropicamide and phenylephrine combined instillation.

Method

One hundred and thirty-one eyes from 66 patients enrolled this cross-sectional study. An extensive ocular examination was carried out prior to tropicamide and phenylephrine instillation. Power and axis value from flat, steep, and mean keratometry were calculated using an Auto Kerato-Refractometer (AKR). Later, topography and tomography maps were evaluated with Pentacam HR® (Oculus, Wetzlar, Germany). Subsequently, a single drop of tropicamide 1% and phenylephrine hydrochloride 10% were instilled twice, with a five-minute gap between each instillation. After 30 minutes, the AKR and Pentacam HR® tests were repeated.

Results

Incyclotorsion was found in 59 eyes (45.1%) and mean absolute incyclotorsion change was 3.91 ± 3.62 degrees (0.10 to 14.20). Excyclotorsion was found in 72 eyes (54.9%) and mean excyclotorsion change was 4.99 ± 5.94 degrees (0.20 to 36.20). We observed that 74.6% and 68.1% of eyes experienced incyclotorsion and excyclotorsion within 0 to 5 degrees, respectively. Fewer patients experienced incyclotorsion and excyclotorsion changes within 5 to 10 degrees, precisely 11.8% and 19.4%, respectively. Eyes that experienced over 10 degrees of incyclotorsion and excyclotorsion were 13.6% and 12.5%, respectively.

Conclusion

Astigmatism axis could change after combined tropicamide and phenylephrine instillation. Reference axis marking in astigmatism correction surgery should be performed under the same circumstances as the astigmatism axis has been measured.

KEYWORDS:

• Tropicamide
• phenylephrine
• astigmatism
• axis

Acknowledgments

The authors acknowledge the support offered by the members of the Regional University Hospital of Malaga. Data collection and support help: Silvia Lozano from Ophthalmology Clinic Dr. Nebro, Málaga, Spain.

Consent to participate

All patients included in this work were adequately informed verbally and in writing of the benefits, characteristics, and risks of the surgeries. All patients signed an informed consent prior to the surgery and after the interview performed with the ophthalmologist.

Consent for publication

All authors consent publication of this article

Data availability statement

Data available on demand

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics approval

This study was conducted in accordance with the tenets of the Helsinki Declaration and obtained Institutional Review Board approval.