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Free-space accommodative response and minus lens-induced accommodative response in pre-school children

Chen AH, O'Leary DJ

Optometry, 2000 Jul;71(7):454-8.
PMID: 15326899

The purpose of this study was to investigate and compare the accommodative accuracy of pre-school children between free-space accommodative stimulus and minus lens-induced accommodative stimulus.

Matched MeSH terms: Vision Tests/methods
New paediatric contrast test: Hiding Heidi low-contrast 'face' test

Chen AH, Mohamed D

Clin Exp Ophthalmol, 2003 Oct;31(5):430-4.
PMID: 14516432

The Hiding Heidi low-contrast 'face' test is a new paediatric contrast test to evaluate the ability to detect objects with low contrast. The purpose of the present study was to compare the Hiding Heidi low-contrast 'face' test (HH) with the Pelli-Robson contrast sensitivity test (PR) and the functional acuity contrast test (FACT) in the low-contrast assessment.

Matched MeSH terms: Vision Tests/methods*
Assessment of Visual Acuity in Children Using Crowded Lea Symbol Charts

Sailoganathan A, Rou LX, Buja KA, Siderov J

Optom Vis Sci, 2018 08;95(8):643-647.
PMID: 30063661 DOI: 10.1097/OPX.0000000000001253

SIGNIFICANCE: Vision charts comprising single Lea symbols surrounded by either flanking bars or flanking Lea symbols are available for measurement of visual acuity in children. However, the results obtained with such charts may not be interchangeable owing to potential differences in the crowding effect.
PURPOSE: The purpose of this study was to compare habitual visual acuity in a sample of young children using two versions of the single Lea symbols charts with different crowding features.
METHODS: Monocular habitual visual acuity was measured in a sample of 77 young children aged between 4 and 6 years using crowded Lea symbols charts with either flanking bars separated from the central symbol by 0.5 optotype width or flanking Lea optotypes separated from the central symbol by 1.0 optotype width.
RESULTS: Mean visual acuity was higher (i.e., lower logarithm of the minimum angle of resolution) with the Lea symbols crowded using flanking optotypes, equivalent to about 1.5 optotype difference. Visual acuity measured with the two charts was significantly correlated; however, the 95% limits of agreement were larger than expected from repeatability studies using Lea symbols.
CONCLUSIONS: Lea symbols with flanking optotypes resulted in higher visual acuity than the Lea symbols with flanking bars, probably as a result of differences in the crowding effect. The two charts showed insufficient agreement, and we do not recommend their use interchangeably. We recommend using the Lea symbols with flanking bars because of the closer flanker-target separation.

Matched MeSH terms: Vision Tests/methods
Fulltext Comparison of visual acuity estimates using three different letter charts under two ambient room illuminations

Chen AH, Norazman FN, Buari NH

Indian J Ophthalmol, 2012 Mar-Apr;60(2):101-4.
PMID: 22446903 DOI: 10.4103/0301-4738.90489

BACKGROUND: Visual acuity is an essential estimate to assess ability of the visual system and is used as an indicator of ocular health status.
AIM: The aim of this study is to investigate the consistency of acuity estimates from three different clinical visual acuity charts under two levels of ambient room illumination.
MATERIALS AND METHODS: This study involved thirty Malay university students aged between 19 and 23 years old (7 males, 23 females), with their spherical refractive error ranging between plano and -7.75D, astigmatism ranging from plano to -1.75D, anisometropia less than 1.00D and with no history of ocular injury or pathology. Right eye visual acuity (recorded in logMAR unit) was measured with Snellen letter chart (Snellen), wall mounted letter chart (WM) and projected letter chart (PC) under two ambient room illuminations, room light on and room light off.
RESULTS: Visual acuity estimates showed no statistically significant difference when measured with the room light on and with the room light off (F1,372 = 0.26, P = 0.61). Post-hoc analysis with Tukey showed that visual acuity estimates were significantly different between the Snellen and PC (P = 0.009) and between Snellen and WM (P = 0.002).
CONCLUSIONS: Different levels of ambient room illumination had no significant effect on visual acuity estimates. However, the discrepancies in estimates of visual acuity noted in this study were purely due to the type of letter chart used.

Matched MeSH terms: Vision Tests/methods*
Fulltext A standardized logarithm of the minimum angle of resolution visual acuity chart in Hindi

Sailoganathan A, Osuobeni EP, Siderov J

Indian J Ophthalmol, 2018 05;66(5):634-640.
PMID: 29676304 DOI: 10.4103/ijo.IJO_1074_17

Purpose: The purpose of this study to develop and calibrate a new Hindi logarithm of the minimum angle of resolution (logMAR) visual acuity chart.
Methods: A new Hindi visual acuity chart was designed to logMAR specifications using Hindi optotypes experimentally selected to have similar relative legibility under equivalent spherical and cylindrical defocus. The chart calibration study was carried out in a large clinical setup in India. Participants who were literate in English and Hindi participated in the study. Visual acuity was measured with the new Hindi logMAR chart and a modified ETDRS (m-ETDRS) logMAR chart. The method of presentation was randomized between the charts. Repeat visual acuity was measured on a subsequent day with a second version of the Hindi logMAR chart.
Results: The Hindi logMAR chart correlated highly with the m-ETDRS logMAR chart (r2 = 0.92); however, the mean visual acuity difference (Hindi logMAR-m-ETDRS logMAR) was nearly one and half lines (0.13 logMAR, 95% confidence interval [CI] = ±0.15 logMAR). The Hindi logMAR chart also proved to be highly repeatable (r2 = 0.99; mean difference 0.005, 95% CI = ±0.04 logMAR).
Conclusion: This study reports the first standardized visual acuity chart developed in Hindi incorporating equal letter legibility and logMAR chart design features. The Hindi logMAR visual acuity chart provides a valid and repeatable tool for the measurement of visual acuity in native Hindi language speakers. Future use of the new Hindi chart should incorporate an increase in optotype size of 0.13 logMAR.

Matched MeSH terms: Vision Tests/methods*