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Background/aims-To evaluate prevalence, aetiology, prognosis, and associated neurological and ophthalmological problems in children with cortical visual impairment (CVI). Methods-The records of 7200 outpatients seen in the paediatric ophthalmology practice over the past 15 years were reviewed in order to compile data concerning CVI. In addition, the authors devised and applied a system for grading visual recovery in order to assess prognosis. Results-CVI occurred in 2.4% of all patients examined. The four most common causes of CVI were perinatal hypoxia (22%), cerebral vascular accident (14%), meningitis (12%), and acquired hypoxia (10%). Most children with CVI had associated neurological abnormalities. The most common were seizures (53%), cerebral palsy (26%) hemiparesis (12%), and hypotonia (5%). Associated ophthalmological problems were esotropia (19%), exotropia (18%), optic nerve atrophy (16%), ocular motor apraxia (15%), nystagmus (11%), and retinal disease (3%). On average, CVI patients improved by two levels as measured by the authors' scale. Conclusion-The majority of children with CVI showed at least some recovery. In this group of children, CVI is often accompanied by additional ophthalmological problems and is nearly always associated with other, serious neurological abnormalities. (Br J Ophthalmol 1999;83:670-675) Cortical visual impairment (CVI) has emerged as the leading cause of low vision in children in developed countries.1-3 Over the past 10 years, researchers have endeavoured to elucidate incidence, prevalence, aetiology, prognosis, and associated neurological and ophthalmological problems in CVI. [4][5][6][7] These studies have been performed in various regions of the world, but there is a paucity of data on the epidemiology of CVI in the United States.We therefore undertook the review of a large paediatric ophthalmology referral practice to determine the occurrence of CVI within this population. We determined the frequencies of various aetiologies of CVI and recorded neurological and ophthalmological problems association with CVI, particularly since other studies of CVI often excluded children with ophthalmological abnormalities. 8-12Our final aim was to assess visual improvement among our cohort of CVI patients. To that end, we devised a method for grading the functional visual perception of our CVI patients. In those patients who returned for follow up visits, we calculated the amount of improvement between visits. Materials and methodsWe reviewed the records of approximately 7200 patients who were seen from 1979 to 1994 in a large paediatric ophthalmology referral practice (WVG, CSH). At the time of the patient's appointment, the diagnosis of "CVI" was based upon (1) vision loss in the absence of signs of anterior visual pathway disease, or (2) vision loss greatly exceeding that which would be expected, given the findings of an ocular examination. Children with nystagmus underwent an electroretinogram (ERG), and we carefully excluded all children where poor visual function cou...

The essential role of the primary visual cortex in visual processing has been extensively studied over the last century or more.

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To assess the frequency of mutations in the CRX, GUCY2D, and RPE65 genes in patients with Leber congenital amaurosis (LCA). Patients: One hundred seventy-six probands with a clinical diagnosis of LCA were from 9 countries, with the largest subgroup being 39 probands from India. Methods: Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of 3 genes (CRX, GUCY2D, and RPE65) known to be associated with LCA. Results: Of the 176 probands, 28 (15.9%) harbored possible disease-causing mutations. The relative contribution of each gene to the total number of mutations was as follows: CRX, 2.8%; GUCY2D, 6.3%; and RPE65, 6.8%. No patients who harbored mutations in these genes had associated systemic abnormalities. Molecular diagnosis allowed definitive genetic counseling in a family affected with Best disease and LCA. Conclusions: Molecular diagnosis may be of benefit to patients affected with LCA. The relative paucity of mutations found in this study suggests that more LCAassociated genes remain to be discovered. Clinical Relevance: Molecular diagnosis can confirm and clarify the diagnosis of LCA. As genotype data accumulate, clinical phenotypes associated with specific mutations will be established. This will facilitate the counseling of patients on their visual prognosis and the likelihood of associated systemic anomalies.

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