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Published on: September 16, 2025
Effect of eyedrops and applanation tonometry on optical biometry
Zacharia Nayer1, Amar Bhat, Preet K Sohal
1From the George Washington University School of Medicine and Health Sciences, Washington, DC (Nayer, Sohal, Murdock); Department of Ophthalmology, The George Washington University, Washington, DC (Bhat, Murdock, Watson, Belyea).
Purpose:
To determine whether eyedrops (phenylephrine, tropicamide, and fluorescein-proparacaine) and Goldmann applanation tonometry (GAT) have an effect on optical biometry measurements for preoperative cataract surgery workup.
Setting:
George Washington University, Washington, DC.
Design:
Nonrandomized controlled trial.
Methods:
Participants older than 18 years with no contraindications to eyedrops or tonometry were recruited. Optical biometry measurements were obtained on a single eye using the Lenstar LS900. One drop each of phenylephrine, tropicamide, and fluorescein-proparacaine was applied to the same eye, and measurements were repeated. GAT was performed, and measurements were repeated. For controls, the contralateral eye was also measured at each interval.
Results:
There was no statistically significant difference in mean predicted postoperative refraction (PPOR) keratometry (K) 1, K2, or axis postdrops and post-GAT 62 eyes (n = 62). After drops were applied, mean central corneal thickness increased from 540 to 542 µm (P = .0002), mean anterior chamber depth (ACD) increased from 3.68 to 3.70 mm (P < .0001), and lens thickness (LT) decreased from 3.66 to 3.65 (P = .001). After GAT, ACD increased to 3.76 mm (P < .0001), and LT increased to 3.60 mm (P < .0001). There was no statistically significant difference in PPOR or other parameters for the control eyes (n = 5).
Conclusions:
GAT and phenylephrine, tropicamide, and fluorescein-proparacaine drops did not affect the primary outcome of PPOR. This suggests that cataract surgery candidates do not need to return for a separate preoperative visit for optical biometry.
