Abstract
Purpose :
The aim here was to explore the relationship between changes in crystalline lens thickness and choroidal thickness before and after cycloplegia with Cyclopentolate 1% while engaging in a near visual task.
Methods :
Twenty-seven healthy adults (14 females), aged 19–22yrs, with normal visual acuity (logMAR≤0.00) and stereo acuity (≤120”) participated in the study. Six participants were myopic (≤-0.50D), 13 emmetropic and eight hyperopic (≥0.50D) as measured with cycloplegic autorefraction (Huvitz HRK-8000A). Acquisition of SD-OCT EDI images with the Heidelberg Spectralis OCT2 and measures of ocular biometry with Zeiss IOLmaster 700 were carried out before and 20 minutes after the instillation of Cyclopentolate 1% (one drop if bluish and two drops if brownish irises) in both eyes. Nineteen engaged in a near visual task using +1.50 D addition and eight engaged in an oral conversation (control) while waiting for the drops to work. Image acquisition and measurements were performed between 1 and 5 pm when diurnal variations in ocular structures are expected to be minimal. Average choroidal thickness (outer boundary of the RPE-Bruchs membrane complex to the inner border of the sclera) of the central 1 mm of the right eye was estimated using semi-automated segmentation software.
Results :
Mean differences (95% CI) in choroidal thickness after cycloplegia were -6.2 (-11.28–-1.16) in the near visual group and -1.2 (-12.97–15.38) µm in the control group. The thinning was significant for the participants in the near visual group, but not in the control group (Wilcoxon signed rank test, p=0.04 and p=0.6). The difference in choroidal thinning between the groups was not significant (Mann-Whitney, p=0.12). The difference in lens thickness after cycloplegia was significant for all participants (paired sample t-test, p<0.001), independent of refractive error (split-plot ANOVA, p=0.3). There was no correlation between the differences in lens thickness and choroidal thickness after cycloplegia (r=0.164, p=0.4).
Conclusions :
The results show that cycloplegia after Cyclopentolate 1% may limit the thinning of choroidal thickness associated with near work, possibly as a consequence of suspended accommodation as indicated by crystalline lens thinning.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.