Why do children with down syndrome have subnormal vision?

Explore characteristics of Down syndrome to find causes of subnormal vision. Explore vision studies to find patterns of decreased vision.

Some obvious potential causes are nystagmus and high refractive error; however, nystagmus and high refractive errors are not a guarantee of poor vision. Accommodative insufficiency is often present, compromising near vision. Vision studies are difficult to compare mainly because of differences in determining and correcting refractive errors. Sweep visually evoked potentials (sVEP) require little effort from the patient and have shown near normal vision in infancy, with improvement leveling off at age 12 to 24 months without further improvement.

People with Down syndrome have a wide variation in visual acuity, but generally 20 / 40 or worse. Both the eye and brain tend to be different in these patients compared to age matched normal subjects. Also, accommodative insufficiency (determined by dynamic retinoscopy) is often present in children Down syndrome, making bifocals a necessary consideration.