Cortical visual impairment (CVI) is bilateral vision loss caused by damage to the posterior visual pathway. CVI is a leading cause of vision impairment in children. Yet, currently, the condition is poorly understood. The goal of this work is to better understand the vision of children CVI: how their vision changes over time and what relationship exists between different measures of acuity for these children.

The purpose of the first project was to evaluate the vision of children with CVI over time. A longitudinal, retrospective evaluation of visual function of 39 patients using the sweep VEP was conducted. Forty-nine percent showed significant improvement of visual acuity, and 47 percent showed significant improvement of contrast threshold over an average of 6.5 years. Further investigation is warranted to distinguish the reasons for the difference between the children who recovered compared to those who remained stable.

Both preferential looking and the sweep VEP are used clinically to assess children with CVI. It is known that VEP testing gives higher acuity values than behavioral tests in patients with vision impairment. The purpose of the second experiment was to evaluate if an initial VEP acuity was predictive of later behavioral acuity, even though the two measures can be quite different at an initial exam. The visual acuity of 33 children was assessed using both methods on two occasions. Even though on average the mean initial VEP measure was 3.5 times better than the initial behavioral measure, 79% of the children either behaviorally met or surpassed their VEP acuity after an average of 7 years.

The purpose of the last experiment was to evaluate the relationship between VEP vernier acuity, VEP grating acuity and preferential looking grating acuity in 29 patients with CVI. It has been shown that vernier acuity is a better predictor of optotype acuity in patients with amblyopia. Vernier acuity showed more loss than VEP grating acuity, and vernier acuity was more similar to the behavioral measure. The agreement of the vernier VEP measure with the behavioral measure suggests that it is a valuable measure of vision function for children with CVI.