Transactions 29th European Strabismological Association Meeting – de Faber (ed) © 2005 European Strabismological Association, ISBN 04 1537 211 9

Influence of near correction on visual perception and perceptional organization skills in Down Syndrome children

G. Satırtav, E.C. Sener & A.S. Sanaç

Hacettepe University School of Medicine, Department of Ophthalmology, Ankara, Turkey

E. Erdog˘an Bakar

Hacettepe University School of Medicine, Department of Neurology, Ankara, Turkey

ABSTRACT: To determine the effect of near spectacle correction on visual perception and perceptional organization skills in children with Down Syndrome, full ophthalmologic examination including dynamic retinoscopy were performed on 11 children with Down Syndrome and the children were grouped according to their accommodation capacity. To determine the visual perception and perceptional organisation skills, Bender Gestalt Motor Perception Test was carried out on two occasions two weeks apart with distant refractive correction on first visit and with 3.0 add on the second visit. When the scores of the first and second performances in the BGMPT are compared within each group; in the children with defective accommodation, the total BGMPT score means in the second performances are found to be significantly lower than the first test score means and in children without defective accommodation, the difference between the mean scores of the first and second performances were found to be statistically insignificant.

1INTRODUCTION

Poor accommodation has been reported to be a common feature of Down Syndrome. It has been first reported by Linstedt who has used a comparison of distance and near visual acuities to evaluate accommodation and has shown that children with visual impairment and children with Down Syndrome frequently have reduced accommodation. Since then this has been supported by several authors. Woodhouse has reported that accommodation in these children is not dependent on the refractive error present and the spectacles to correct the distant refractive error do not improve the accommodative response. Furthermore age, angular subtense of the target used for the fixation and cognitive factors could not fully account for the poor accommodation in these children.

To the best of our knowledge, there has not been any study done concerning the effect of near refractive correction, to compensate for the defective accommodation, on the child’s visual perception. The aim of the present investigation is to determine the effect of near spectacle correction on visual perception and perceptional organizational skills in children with Down Syndrome.

2SUBJECTS AND METHODS

2.1Participants

Thirteen individuals with a primary diagnosis of Down Syndrome were the subjects in this study. Two children were recruited but excluded from the final sample for failure to complete the testing. There were four females and seven males and the ages ranged from 80 months to 158 months with a mean age of 130,36 months at the time of testing. Permission to their ophthalmologic examination and application of the tests was obtained from each subject’s parent or guardian.

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2.2Procedures

All children with Down Syndrome underwent full ophthalmologic examination. Visual acuity was measured using the Lea and the Snellen chart according to the child’s cooperation. Strabismus was identified with the cover test. Dynamic retinoscopy and cycloplegic refraction were performed on each child. Dynamic retinoscopy is done sitting about 50 cm in front of the child observing the retinoscopic streak light movement while the child is looking straight ahead at distance with both eyes open. A small picture that attracts interest is then introduced 20–30 cm in front of the child. The child is then encouraged to fixate the near target constantly. If normal accommodation is present, the examiner observes a very distinct shift from “with” movements to “against” movements. If, when presenting the target, this shift did not take place in spite of a cooperative child, the accommodation response was classified as accommodation weakness. In most cases the accommodative state of the right eye was assessed. However, in one child with strabismus and a fixating left eye accommodation was assessed from the left eye. Children were grouped according to their accommodative responses as “children with accommodative weakness” and “children without accommodative weakness”.

To determine the visual perception and perceptional organization skills, Bender Gestalt Motor Perception Test (BGMPT) was carried out on each child by one of the authors (EEB). The test was done on two occasions two weeks apart, with best corrected vision for distance on first visit and with 3.0 additions on the second visit. The BGMPT is a psychological assessment used to evaluate visual motor functioning, visual perceptual skills in children and adults ages 3 and older.

The original BGMPT was developed in 1938 by psychiatrist Lauretta Bender. The standard BGMPT consists of 9 figures of geometric designs (numbered A and 1–8) each on its own 3 5 inches card. An examiner presents each figure to the test subject one at a time and asks the subject to copy it on to a single piece of blank paper. The only instruction given to the subject is that he or she should make the best reproduction of the figure possible. The test is not timed; results are scored based on accuracy and organization. Common features considered in evaluating the drawings are attachment, rotation, distortion, symmetry and perseveration. Each mistake done while drawing each figure is scored as “1” and the maximum score that can be obtained is “30”.(Koppitz, 1964). The majority of more than 20 different reliability studies reported by Koppitz reveals correlation coefficients in the .80 range and suggests that normal elementary school children show relatively stable patterns of BGMPT scores from one administration to the next.

2.3Statistics

The data was analyzed statistically in the Statistical Package for Social Sciences (SPSS, 11.5). The score differences obtained from the BGMPT in the first and second visits for the two groups of children were compared using Mann Whitney Test. P 0.05 was chosen as the level of significance.

3RESULTS

The visual acuities of the children ranged from 0.4 to 1.0 (mean 0.52) (Table 1)

Only one of the subjects (%9.1) had strabismus (right esotropia) and others did not have any eye movement disorder (Table 1).

Seven of the children (%63.6) had low grade hypermetropia (spherical equivalent right eye 2.0), one (%9.1) had high grade hypermetropia (spherical equivalent of the right eye 4.0 D), one (%9.1) had myopia and two (%18.2) were emmetropes (Table 1).

When the total score and subscores of the first and second performances in the BGMPT are compared within each group;

– In the children with defective accommodation, the total BGMPT score means in the second performances (X 11,67) are found to be significantly lower than the first test score means (X 9,00) (P 0,034).

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Table 1. Individual cross-sectional data on 11 children on the first examination.

* Group 1: children without defective accommodation. Group 2: children with defective accommodation.

–In the children without defective accommodation, the difference between the mean scores of the first (X 13,00) and second performances (X 13,40) were found to be statistically insignificant (P 0,715).

–In the children with defective accommodation, the total BGMPT attachment subscore means in the second performances (X 2,00) are found to be significantly lower than the first test subscore means (X 3,67) (P 0,039).

–In the children without defective accommodation, the difference between the mean attachment subscores of the first (X 4,40) and second performances (X 4,60) were found to be statistically insignificant (P 0,564).

When the total and subtotal Bender score differences of the two performances are compared between each group;

–The mean difference of the total Bender scores in the group with defective accommodation (X 7,75) is found to be higher than the mean difference of the total Bender scores in the group without defective accommodation (X 3,90) and the difference was found to be statistically significant (P 0,05).

–The mean difference of the attachment subscore in the group with defective accommodation (X 1,67) is found to be higher than the mean difference of the attachment subscores in the group without defective accommodation (X 0,20) and the difference was found to be statistically significant (P 0,01).

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4CONCLUSION

The majority of children with Down Syndrome are probably visually impaired at near distances. Uncorrected refractive errors and poor accommodation might be a factor in the educational achievements of children with Down Syndrome. The learning ability of these children might be hampered by the inability to see near objects clearly or comfortably especially in a learning environment and it is imperative that clinicians and educators are made aware of this.

In this study we have shown that near correction may have an impact on their near work. Therefore, the ophthalmologic examination of these children should include dynamic retinoscopy to see their accommodation abilities and near correction for the children with accommodation deficit can be considered in the visual rehabilitation.

REFERENCES

Cregg, et al. (2001) Accommodation and refractive error in children with Down Syndrome: cross-sectional and longitudinal studies. Invest Ophthalmol Vis Sci 2001;42:55–63.

Linstedt (1983) Failing Accommodation in cases of Down Syndrome; Ophthalmic Paediatr Genet. 1983;3:191.

Mitchell-Burns (2000) Performance of children with and without learning disabilities on Canter’s Background Interference Procedure and Koppitz’s scoring system for the Bender test. Percept Mot Skills. 2000 Jun;90(3 Pt 1):875–82.

Pires da Cunha et al. (1996) Ocular Findings in Downs Syndrome. Am J Ophthalmol. 122:236–244. Woodhouse et al. (1993) Reduced Accommodation in children with Down Syndrome; Invest Ophthalmol Vis

Sci 34:2382–2387.

Woodhouse, et al. (1996) Visual acuity and accommodation in infants and young children with Down Syndrome. J Int Dis Res.;40:49–55.

Woodhouse, et al. (2000) The effect of age, size of target and cognitive factors on accommodative responses of children with Down Syndrome. Invest Ophthalmol Vis Sci;41:2479–2485.

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