Visual abilities of students with severe developmental delay in special needs education – a vision screening project in Northern Jutland, Denmark

Abstract

ABSTRACT.Purpose: To investigate the visual abilities of students with severe developmental delay (DD) age 6-8 starting in special needs education. Methods: Between 1 January 2000 and 31 December 2008, we screened all students with severe DD starting in special needs schools in Northern Jutland, Denmark for vision. All students with visual acuities £6 ⁄ 12 were refractioned and examined by an ophthalmologist. Results: Of 502 students, 56 (11%) had visual impairment (VI) [visual acuity (VA) £ 6 ⁄ 18], of which 21 had been previously undiagnosed. Legal blindness was found in 15 students (3%), of whom three had previously been undiagnosed. Students tested with preferential looking systems (N = 78) had significantly lower visual acuities [VA (decimal) = 0.55] than students tested with ortho types [VA (decimal) = 0.91] and had problems participating in the colour and form tests, possibly due to cerebral VI. The number of students with decreased vision identified by screening decreased significantly during the study period (r = 0.724, p = 0.028). The number of students needed to be screened to find one student with VI was 24 and to identify legal blindness 181 needed to be screened. Conclusion: Visual impairment is a common condition in students with severe DD. Despite increased awareness of VI in the school and health care system, we continued to find a considerable number of students with hitherto undiagnosed decreased vision.

The measurement of visual acuity in children: an evidence‐based update

“…Resolution acuity tasks can provide a rapid and objective assessment in these populations. For example, success rates with both TAC and Cardiff acuity cards are very high with many studies reporting co‐operation for over 90 per cent of patients …”

“…83 This may be due to the fact that, like grating acuity, Cardiff acuity cards are poor at detecting uncorrected refractive errors. 84 Resolution acuity tasks, such as the CAT are not only used with infants and toddlers but are often useful in other populations, such as children with developmental delay, 85 patients with neurological conditions 86 and deaf-blind populations. 87 Visual impairment can be prevalent in these populations and appropriate management may be delayed due to difficulties in obtaining accurate measurements of visual acuity using recognition-based tests that place demands on cognitive function and communication.…”

“…For example, success rates with both TAC and Cardiff acuity cards are very high with many studies reporting co-operation for over 90 per cent of patients. 85,87 Grating acuity measures can also be valuable in older patients with cognitive dysfunction; [88][89][90] however, this is not always the case. Chriqui and colleagues 91 recently reported results from three different groups of older participants: a group of young adults (mean age 25 years), a group of older adults without neurological disease (mean age 70 years) and a group of older adults with cognitive impairment.…”

Retrospective Analysis of Ophthalmic Ailments in Children Attending the Child Development Unit in a Tertiary Care Hospital in South India

“…(1,2) Eye problems sometimes may be mistaken for learning disabilities. Children with very severe attention difficulties may not be able to maintain fixation during vision testing and are at risk of being misdiagnosed as 'blind.…”

Identifying visual difficulty in children with special educational needs: where should we look?

“…For certain groups, such as children with Down's syndrome, the increased risk of adverse visual outcomes and benefits of active ophthalmological surveillance are well documented. References to an increased risk of visual difficulties in more heterogeneous groups of children, such as those with ‘developmental delay’ or neurological impairment, are however more likely to be found in the ophthalmological literature 3 4…”