Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence

Abstract

The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.

Correlation study of changes in visual acuity, pupil diameter, Kappa angle, and Alpha angle after phacoemulsification surgery combined with multifocal IOL implantation

“…Because the contact between the iris and the tip of the phacoemulsi cation handle is inevitable, the release of in ammatory mediators can not be ruled out, which is the main reason for the localized change of the pupil after operation. Similarly, Ba-AliS [21] also proposed that the effect of cataract surgery on dark adaptation pupil size and maximum pupil contraction could be observed within 3 weeks after operation, and basically recovered 3 months after operation, which was consistent with the self-limitation of pupil contraction proposed by our study. However, KanellopoulosAnastasiosJohn et al [22] showed statistically signi cant changes in pupil size and shape after cataract surgery, and the average reduction of pupil size was between-11% and-13%, and pupil eccentricity decreased greatly (− 39%).In this study, there is no difference in pupil size between one month after operation and before operation, which requires us to take a longer observation time to determine the long-term changes of pupils.…”

Pupil dependence assessment with multifocal intraocular lenses through visual acuity and contrast sensitivity defocus curves

“…Differences can be explained by variations in pupil dynamics between methods for measuring visual performance. When measuring distance-corrected visual acuities, pupil diameter has been reported to be reduced by −0.23 mm/D, 18 and then a mean reduction of −0.58 mm can be expected between infinite and 40 cm (2.5 D). However, it has not been demonstrated that this reduction also appears with defocus lenses aimed at varying the vergence of light simulating the condition of approximation of an optotype.…”

“…10,23 Second, pupil varies with vergence distance, a mean reduction around 0.5 mm can appear at near versus far distance under photopic conditions. 18,22 This can lead to differences between direct measurements of distance-corrected visual acuities and those obtained with defocus curves. Therefore, visual acuity derived from defocus curves should not be considered as interchangeable with direct measurement of distance-corrected visual acuity at different distances in clinical studies.…”