Visual Problems Common in Children with Dyslexia

MedicalResearch.com Interview with:

Aparna Raghuram, OD, PhD Optometrist, Department of Ophthalmology Instructor, Harvard Medical School

Dr. Raghuram

Aparna Raghuram, OD, PhD
Optometrist, Department of Ophthalmology
Instructor, Harvard Medical School

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Developmental dyslexia is a specific learning disability of neurobiological origin whose core cognitive deficit is widely believed to involve language (phonological) processing. Although reading is also a visual task, the potential role of vision has been controversial, and experts have historically dismissed claims that visual processing might contribute meaningfully to the deficits seen in developmental dyslexia.

Nevertheless, behavioral optometrists have for decades offered vision therapy on the premise that correcting peripheral visual deficits will facilitate reading. Yet there is a surprising dearth of controlled studies documenting that such deficits are more common in children with developmental dyslexia, much less whether treating them could improve reading.

In the present study, we simply assessed the prevalence and nature of visual deficits in 29 school aged children with developmental dyslexia compared to 33 typically developing readers. We found that deficits in accommodation 6 times more frequent in the children with developmental dyslexia and deficits in ocular motor tracking were 4 times more frequent.

In all, more than three-quarters of the children with developmental dyslexia had a deficit in one or more domain of visual function domain compared to only one third of the typically reading group.

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Sildenafil May Cause Visual Problems in Genetically Predisposed

Dr. Michael Kalloniatis School of Optometry and Vision Science, UNSW Australia, Sydney, New South Wales, Australia; Centre for Eye Health, Sydney, New South Wales, Australia;MedicalResearch.com Interview with:
Dr. Michael Kalloniatis
School of Optometry and Vision Science, UNSW Australia, Sydney, New South Wales, Australia; Centre for Eye Health, Sydney, New South Wales, Australia;

Medical Research: What are the main findings of the study? What was most surprising about the results?

Dr. Kalloniatis: Normal mice given a single sildenafil treatment had a transient loss of visual function which recovered in two days. Carrier mice (mice which carry a single copy of a mutation that commonly causes recessive Retintis Pigmentosa) showed a supernormal visual response (a response much larger than the norm) to sildenafil which took two weeks to recover to normal. Carrier mice also showed an increase in an early marker for apoptosis (a protein which suggest cells may be preparing to die) suggesting sildenafil may cause retinal degeneration in these mice.

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