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Jennifer J Bu, Ruti Sella, Rebecca R Lian, Jenny Q Hu, Helena E Gali, Evan Walker, Eitan Livny, Natalie A Afshari; Pupillary dilation and axial length in highly myopic patients. Invest. Ophthalmol. Vis. Sci. 2022;63(7):4313 – A0018.
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© ARVO (1962-2015); The Authors (2016-present)
To determine how high myopia impacts pharmacological pupillary dilation, and to evaluate the relationship between the rate and extent of pharmacological pupillary dilation and axial length (AL).
Patients were recruited from Shiley Eye Institute at the University of California San Diego, and grouped into high myopes, defined as one or both eyes having a spherical equivalent (SE) refraction greater than -6 diopters (D) or AL>26mm, and controls (SE less than -6 D and AL<26mm). Inclusion criteria were: phakic, aged 21 to 100, and planning to get pharmacological pupillary dilation as part of their eye exam. Exclusion criteria were: current use of eye drops other than artificial tears, prior intraocular or refractive surgery, iris or angle abnormalities, history of eye inflammation, previous adverse reaction to dilating drops, or diabetes. Dilation was achieved with 1 drop of tropicamide 1% and phenylephrine 2.5% in each eye. Pupil size was measured utilizing a Colvard pupillometer and the Cirrus HD-OCT (manual measurement on anterior segment scans) at full and dim light prior to dilation, then 15 and 30 minutes after dilation. AL and keratometry were measured using the Zeiss IOLMaster 700. Two-sample t-tests and generalized estimating equations (GEE) models were performed using R software.
Thirty-four patients (68 eyes) participated in the study. The average age was 49 years and 70.5% were females. Sixteen patients were high myopes (average SE -7.14 D, range -4.75 to -11) and 18 were controls (average -1.06 D, range +2 to -5.5). Fully dilated pupil size at 30 minutes was significantly correlated with both SE refraction (r=-0.59, p < 0.001) and AL (r=0.44, p < 0.001), indicating eyes with higher myopia, as measured by both AL and refractive error, dilated more. When grouped by AL, 16 eyes had AL>26 mm (range 26.03-28.58mm) and 48 eyes had AL<26 mm (range 22.77-25.99mm), with eyes>26mm dilating to a greater extent than eyes<26mm at both 15 (p = .05) and 30 minutes (p < .0005).
Highly myopic patients dilate to a larger pupillary size compared to other patients. The positive correlation between dilation and axial length may be explained by the difference in elasticity of the sclera and thickness of the iris in highly myopic eyes. Predicting dilation based on extent of myopia could facilitate intraocular surgery planning and reduce clinic wait times for myopic patients.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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