Static and Dynamic Measurements of Accommodation in Individuals with Down Syndrome

Anderson, Heather A; Manny, Ruth E.; Glasser, Adrian; Stuebing, Karla K.

doi:10.1167/iovs.10-5301

Cited by 31 publications

(40 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These data are in agreement with Ghasia et al, 23 who reported CP VA (n ¼ 50) to be ''approximately two lines (0.22 logMAR) worse than controls,'' and Anderson et al, 24 who reported mean VA of their DS group (n ¼ 35) to be þ0.35 logMAR worse than in controls. However, both these studies pooled VA data from a number of different acuity tests, including spatial sweep VEP, 23 preferential looking, 24 and letter and picture uncrowded and crowded opytotypes (with and without logMAR design). In the current study, VA was assessed using a single technique, which allows more rigorous comparison across participants and with reference data.…”

Section: Discussionsupporting

confidence: 90%

Low-Contrast Acuity Measurement: Does It Add Value in the Visual Assessment of Down Syndrome and Cerebral Palsy Populations?

Little

McCullough

McClelland

et al. 2013

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

PURPOSE. Children with Down syndrome (DS) and cerebral palsy (CP) often have reduced visual acuity (VA). This study assessed VA and low-contrast acuity (LCA) with Lea symbols in DS and CP populations to explore whether LCA measures provide useful additional information about visual performance. VA and LCA were also measured in a large group of typically developing young people.METHODS. High-contrast VA and LCA performance was measured monocularly using crowded Lea symbols with 45 young people with CP (mean age 11.8 -4 years), 44 with DS (mean age 10.5 -3 years), and 211 controls (mean age 11.4 -3 years). Refractive status was confirmed with cycloplegic retinoscopy.RESULTS. DS and CP groups had significantly lower acuities than controls at all contrasts (P < 0.001). Mean (-SD) high-contrast VA was as follows: DS ¼þ0.39 -0.2 logMAR; CP ¼þ0.18 -0.2 logMAR; controls ¼À0.04 -0.1 logMAR. Mean 2.5% LCA was as follows: DS ¼þ0.73 -0.2 logMAR; CP ¼þ0.50 -0.2 logMAR; controls ¼ þ0.37 -0.1 logMAR. For controls, the mean difference between VA and 2.5% LCA was 0.40 logMAR (95% limits of agreement, -0.22 logMAR). While there was a positive relation between VA and 2.5% LCA scores (linear regressions, P < 0.0001), considerable variation existed, with VA explaining only 36% of the variance in LCA performance for control data.CONCLUSIONS. VA and LCA performance was significantly poorer in DS and CP groups than in controls, and high-contrast VA did not reliably predict low-contrast performance. Therefore both high-and low-contrast acuity assessment are valuable to fully describe an individual's visual function, and this may be particularly relevant in DS and CP in cases in which patients are unable to articulate visual difficulties. Age-specific reference data from a large sample of typically developing young people across a broad age range are presented for clinicians using high-and low-contrast Lea symbols. (Invest Ophthalmol Vis Sci. 2013;54:251-257)

show abstract

Section: Discussionsupporting

confidence: 90%

Low-Contrast Acuity Measurement: Does It Add Value in the Visual Assessment of Down Syndrome and Cerebral Palsy Populations?

Little

McCullough

McClelland

et al. 2013

Invest. Ophthalmol. Vis. Sci.

View full text Add to dashboard Cite

show abstract

“…These features are particularly advantageous when working with uncooperative subjects [2–4] and in situations where high sampling rates are required [3,5–7]. Accordingly, a number of commercial devices have been developed using this technique for vision screening of infants and young children, and also for monitoring accommodative performance (e.g., MCS PowerRefractor [8]).…”

Section: Introductionmentioning

confidence: 99%

Empirical variability in the calibration of slope-based eccentric photorefraction

et al. 2013

View full text Add to dashboard Cite

Refraction estimates from eccentric infrared (IR) photorefraction depend critically on the calibration of luminance slopes in the pupil. While the intersubject variability of this calibration has been estimated, there is no systematic evaluation of its intrasubject variability. This study determined the within subject inter- and intra-session repeatability of this calibration factor and the optimum range of lenses needed to derive this value. Relative calibrations for the MCS PowerRefractor and a customized photorefractor were estimated twice within one session or across two sessions by placing trial lenses before one eye covered with an IR transmitting filter. The data were subsequently resampled with various lens combinations to determine the impact of lens power range on the calibration estimates. Mean (±1.96 SD) calibration slopes were 0.99 ± 0.39 for North Americans with the MCS PowerRefractor (relative to its built-in value) and 0.65 ± 0.25 Ls/D and 0.40 ± 0.09 Ls/D for Indians and North Americans with the custom photorefractor, respectively. The ±95% limits of agreement of intrasubject variability ranged from ±0.39 to ±0.56 for the MCS PowerRefractor and ±0.03 Ls/D to ±0.04 Ls/D for the custom photorefractor. The mean differences within and across sessions were not significantly different from zero (p > 0.38 for all). The combined intersubject and intrasubject variability of calibration is therefore about ±40% of the mean value, implying that significant errors in individual refraction/accommodation estimates may arise if a group-average calibration is used. Protocols containing both plus and minus lenses had calibration slopes closest to the gold-standard protocol, suggesting that they may provide the best estimate of the calibration factor compared to those containing either plus or minus lenses.

show abstract

“…A sensory mechanism has also been suggested as explanation of the underaccommodation demonstrated in DS711, in that individuals with DS may have an increased depth of focus or increased tolerance of retinal blur, allowing underaccommodation to occur without the perception of an out-of-focus image. The authors previously demonstrated a significant relationship between BCVA and the accommodative response in children with DS; as BCVA worsened so did the accuracy of the accommodative response12.…”

Section: Discussionmentioning

confidence: 99%

“…An accommodative deficit is a common clinical finding in both adults and children with Down syndrome (DS)4567891011, often requiring clinical intervention such as the provision of bifocal spectacle correction to minimise near visual impairment. The aetiology of hypoaccommodation in DS is not yet clear, with a variety of suggestions including: a sensory deficit711, a mechanical limitation78911 or an atypical relationship between the accommodative and vergence systems689.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Determining the relative contribution of retinal disparity and blur cues to ocular accommodation in Down syndrome

Doyle

Saunders

Little

2017

Sci Rep

View full text Add to dashboard Cite

Individuals with Down syndrome (DS) often exhibit hypoaccommodation alongside accurate vergence. This study investigates the sensitivity of the two systems to retinal disparity and blur cues, establishing the relationship between the two in terms of accommodative-convergence to accommodation (AC/A) and convergence-accommodation to convergence (CA/C) ratios. An objective photorefraction system measured accommodation and vergence under binocular conditions and when retinal disparity and blur cues were removed. Participants were aged 6–16 years (DS n = 41, controls n = 76). Measures were obtained from 65.9% of participants with DS and 100% of controls. Accommodative and vergence responses were reduced with the removal of one or both cues in controls (p < 0.007). For participants with DS, removal of blur was less detrimental to accommodative responses than removal of disparity; accommodative responses being significantly better when all cues were available or when blur was removed in comparison to when proximity was the only available cue. AC/A ratios were larger and CA/C ratios smaller in participants with DS (p < 0.00001). This study demonstrates that retinal disparity is the main driver to both systems in DS and illustrates the diminished influence of retinal blur. High AC/A and low CA/C ratios in combination with disparity-driven responses suggest prioritisation of vergence over accurate accommodation.

show abstract

Static and Dynamic Measurements of Accommodation in Individuals with Down Syndrome

Cited by 31 publications

References 31 publications

Low-Contrast Acuity Measurement: Does It Add Value in the Visual Assessment of Down Syndrome and Cerebral Palsy Populations?

Low-Contrast Acuity Measurement: Does It Add Value in the Visual Assessment of Down Syndrome and Cerebral Palsy Populations?

Empirical variability in the calibration of slope-based eccentric photorefraction

Determining the relative contribution of retinal disparity and blur cues to ocular accommodation in Down syndrome

Contact Info

Product

Resources

About