Accommodation, pupil diameter and myopia

Abstract

Concurrent measurements of steady-state accommodation response/stimulus curves and of pupil diameter were made in groups (n = 20) of young, adult myopes [age (mean ± SD) 23.1 ± 4.5 years, mean-sphere error (MSE) )3.06 ± 2.35 D, range )0.60 to )8.54 D] and emmetropes (mean age 25.3 ± 5.7 years, mean MSE )0.07 ± 0.26 D, range )0.50 to +0.50 D). The aim of this study was to explore the possibilities that pupil diameters with relaxed accommodation were larger, and that accommodative miosis was weaker, in the myopic group. Such behaviour would lead to relatively greater degradation of the retinal images in the myopic group, even though aberrations at constant pupil diameter and dioptric accommodative lags in the two groups were the same: this might result in excessive axial growth and further myopia development. No evidence for any systematic refractive dependence of pupillary characteristics or accommodative responses was found. Interestingly, those subjects whose response/stimulus curves had a higher slope tended to display greater accommodative miosis, irrespective of their refractive error.

Assessment of Pupil Diameters of Emmetropes and Myopes under Photopic, Mesopic and Scotopic Conditions, Using the Infrared Pupillometer Integrated Within Schwind Sirius Multifunctional Diagnostic Device

“…34,35,43 Subbaram and Ballimore found no significant differences in the pupil diameters of age-matched myopes and emmetropes at different levels of accomodation. 43 He et al stated that myopes had difficulty in accomodative relaxation, which resulted in accomodation lag.…”

“…Some studies found no difference in pupil size between myopes and emmetropes, while others reported that myopes had larger pupils than emmetropes. 15,29,[33][34][35][36][37][38] Tscherning states that the deeper anterior chamber in the myope makes the pupil appear larger. 39 Shaun et al stated that myopes showed maximum values for anterior chamber depth (ACD) and PD than emmetropes and hyperopes in photopic and scotopic conditions.…”

Changes in anterior chamber eye during accommodation as assessed using a Dual Scheimpflug system

“…The differences between our results and those of Baikoff et al could be related to the different experimental conditions used. Baikoff et al used -10 D as the maximum accommodation, whereas the maximum accommodation stimulus in our study was -4 D. Chartman et al (29) studied changes in pupil size during accommodation using a Hartman-Shack wavefront sensor. The mean rate of change in PD during accommodation was -0.21 ± 0.15 mm·D -1 .…”

“…Table 1 is a compilation of the results of all studies that evaluated at least one of these three eye metrics during accommodation. Studies assessing the changes in central ACD , mean ACA (16) , and PD (3,7,26,28,29) during accommodation concluded that these metrics decreased after increasing the stimulus vergence. Figure 1 The changes in the peripheral ACD and ACA at different meridians during accommodation have not been studied.…”

“…Such studies will enable the development of new anterior chamber IOLs that better fits the anterior chamber eye. Several studies have evaluated the changes in pupil diameter during accommodation (3,7,26,28,29) . However, four of these studies (3,7,26,28) included myopic or hyperopic subjects and mea-sured the changes in pupil diameter with stimuli vergences beyond 5 D. Further, a Scheimpflug system has not been used to study the changes in pupil that occur during accommodation.…”