PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 1584622

Dynamic retinoscopy and accommodation.

H Whitefoot·W N Charman
View original source ↗Export metadata ↓

Abstract

The added positive lens power required for low and high neutrals at a distance of 1/3 m is determined as a function of age for a sample of 221 clinically normal subjects, aged between 10 and 80 years. These dynamic retinoscopy results are compared with corresponding laser optometer measurements of the levels of accommodation under each condition. Dark focus (tonic accommodation) measurements are carried out on a further sample of 58 subjects. Although the mean results of dynamic retinoscopy agree with those found by earlier authors, on the basis of our sample it is concluded that the considerable scatter in neutral values found in normal subjects at any age limits the usefulness of the technique as an indication of abnormality in near responses. Much of this scatter in pre-presbyopic subjects appears to be related to individual variation in the level of tonic accommodation, although near phoria may also play some role.

Explore related subjects

Accommodation, OcularAdolescentAdultAge FactorsAgedAged, 80 and overChildDarknessHumansMiddle AgedOptometryPresbyopiaRefraction, OcularRefractive ErrorsJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

H Whitefoot, W N Charman. 1992. Dynamic retinoscopy and accommodation.. https://pubmed.ncbi.nlm.nih.gov/1584622/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

Conceptual model of human blur perception.

An empirically based, conceptual model of human blur perception is presented. It incorporates the concepts of blur detection and blur discrimination in depth, and across the central and peripheral retina, in two- and three-dimensional visual space. Key aspects of the model are its dynamic nature, predictability regarding the blur-based depth-ordering of objects, patterns of retinal defocus with far and near viewing, and interactions related to retinal defocus between the central and peripheral retina. Furthermore, a two-dimensional schematic representation of the blur-free region during near viewing is depicted in dioptric space. This model has implications with respect to accommodative control, depth perception, and refractive error development and progression.

Accommodation, Ocular↗
PubMed2007

The effect of human in vivo accommodation on crystalline lens stability.

AIM: To determine the effect of human in vivo accommodation on the stability of the crystalline lens. METHODS: Using a dual Purkinje image (DPI) eyetracker, the phase-time difference and amplitudes of Purkinje images I (P(I)) and IV (P(1V)) were measured in 37 normal emmetropic subjects (34 women and 3 men; mean age 19.8, range 18-22 years) when they changed focus from 70 to 15 cm and simultaneously rotated their heads horizontally from side to side or made horizontal saccades between two targets 6.8 degrees apart. RESULTS: When the subjects changed focus from 70 to 15 cm and rotated their heads or made eye saccades, the phase-time difference between P(I) and P(IV) decreased. During saccades, the amplitude of both P(I) and P(IV) overshoots significantly increased with focus at 15 cm; however, their ratio (P(IV) overshoot amplitude/P(I) overshoot amplitude) significantly declined. CONCLUSIONS: The lens is stable during accommodation. The implications of these findings on the mechanism of accommodation are discussed.

Accommodation, Ocular↗
PubMed2007

Synchrony dual-optic accommodating intraocular lens. Part 2: pilot clinical evaluation.

PURPOSE: To evaluate the clinical outcomes of an accommodating dual-optic intraocular lens (IOL). SETTING: Private practice and university centers. METHODS: A prospective noncomparative case series with retrospective control comprised 21 patients (26 eyes) scheduled for small-incision extracapsular cataract extraction by phacoemulsification with implantation of the Synchrony dual-optic accommodating IOL (Visiogen) (accommodating IOL group) and 10 patients who had small-incision extracapsular phacoemulsification with implantation of a monofocal, single-optic IOL at least 6 months previously (control group). Patients were examined 1, 3, 6, and 12 months after surgery. Defocus curves in the accommodating IOL group were compared with those in the control group. The main outcome measures were postoperative distance uncorrected and best corrected visual acuity; near uncorrected, distance corrected, and near corrected visual acuity; and accommodative range based on defocus curves. RESULTS: Twenty-four eyes were available at the 6-month follow-up visit. All eyes had best corrected distance visual acuity of 20/40 or better, and 19 eyes (79%) had an uncorrected distance visual acuity of 20/40 or better. Uncorrected near visual acuity was 20/40 or better in all eyes. With distance correction, 23 eyes (96%) had an acuity of 20/40 or better at near. Defocus curve analysis suggested a mean accommodative range of 3.22 diopters (D) +/- 0.88 (SD) (range 1.00 to 5.00 D) in the accommodating IOL group and 1.65 +/- 0.58 D in the control group (range 1.00 to 2.50 D) (P<.05). CONCLUSION: The Synchrony dual-optic IOL shows promise as an option to provide accommodative function in pseudophakic patients.

Accommodation, Ocular↗