Factors Influencing Pseudo-Accommodation—The Difference between Subjectively Reported Range of Clear Focus and Objectively Measured Accommodation Range

Abstract

The key determinants of the range of clear focus in pre-presbyopes and their relative contributions to the difference between subjective range of focus and objective accommodation assessments have not been previously quantified. Fifty participants (aged 33.0 ± 6.4 years) underwent simultaneous monocular subjective (visual acuity measured with an electronic test-chart) and objective (dynamic accommodation measured with an Aston open-field aberrometer) defocus curve testing for lenses between +2.00 to −10.00 DS in +0.50 DS steps in a randomized order. Pupil diameter and ocular aberrations (converted to visual metrics normalized for pupil size) at each level of blur were measured. The difference between objective range over which the power of the crystalline lens changes and the subjective range of clear focus was quantified and the results modelled using pupil size, refractive error, tolerance to blur, and ocular aberrations. The subjective range of clear focus was principally accounted for by age (46.4%) and pupil size (19.3%). The objectively assessed accommodative range was also principally accounted for by age (27.6%) and pupil size (15.4%). Over one-quarter (26.0%) of the difference between objective accommodation and subjective range of clear focus was accounted for by age (14.0%) and spherical aberration at maximum accommodation (12.0%). There was no significant change in the objective accommodative response (F = 1.426, p = 0.229) or pupil size (F = 0.799, p = 0.554) of participants for levels of defocus above their amplitude of accommodation. Pre-presbyopes benefit from an increased subjective range of clear vision beyond their objective accommodation due in part to neural factors, resulting in a measured depth-of-focus of, on average, 1.0 D.

IMI Accommodation and Binocular Vision in Myopia Development and Progression

“…The need for accommodation will dependent on the range of clear focus which is influenced by monofocal and chromatic aberrations, pupil size, 135 and neural factors. 136 For a constant pupil diameter, differences in ocular aberrations between myopes and emmetropes are observed and are variable in both accommodative and nonaccommodative states. 137 , 138 Attempts to slow myopia progression using interventions targeted at improving accommodative lag, such as progressive lens wear groups (PALs) have been largely unsuccessful, even when including children with high lags of accommodation and near esophoria.…”

Visual function assessment of posterior-chamber phakic implantable collamer lenses with a central port

“…To evaluate subjective visual quality at different distances, the visual acuity of the single and double eyes of patients was examined at 5 m and 40 cm, respectively. The traditional method for whole-course visual acuity examination is mainly the defocus curve, which needs to be completed under a comprehensive optometer, and has the disadvantages of poor repeatability and low reproducibility, as well as being time consuming (13,14). The visual acuity levels of 5m in monocular eye, 40 cm in monocular eye, 5m in binocular eyes, and 40 cm in binocular eyes measured by Binoptometer 4P were all improved after surgery, and the differences were statistically significant.…”

Akkommodation

“…Dazu gehören z. B. die größere Schärfentiefe bei einer engen Pupille, bei höheren Aberrationen der Hornhaut, bei Pseudophaken die Verschiebung der Kunstlinse bei Nahblick nach vorne und auch neuronale Prozesse, die bei Bildunschärfe einsetzen (Überblick in [5]). Die Testfigur wird so weit angenähert, bis der feine Strich zwischen den beiden Blöcken unscharf gesehen wird.…”