Changes in the optic disc excavation of children affected by cerebral visual impairment: A tomographic analysis

PURPOSE. To obtain quantitative data on the optic disc excavation in children affected by cerebral visual impairment (CVI) by using the Heidelberg Retinal Tomograph (HRT)-II (Heidelberg Engineering, Heidelberg, Germany). METHODS. A total of 24 subjects affected by CVI (mean age, 7.28 years) were examined: 16 in alert conditions and 8 under general anesthesia. The following parameters of the optic nerve head were examined: disc area, cup area, rim area, cup volume, rim volume, cup-to-disc area ratio, mean cup depth, maximum cup depth, cup shape measure, and mean retinal nerve fiber layer (RNFL) thickness. The tomographic results in children with CVI were compared with those of 88 normal, alert subjects of similar age. RESULTS. The optic disc of patients with CVI appeared smaller than normal. Its excavation, however, was more pronounced. Several tomographic parameters were altered in CVI-affected subjects. Statistical analysis showed a highly significant probability in cup-to-disc area ratio (P <0.01, both eyes), rim area (P <0.01, both eyes), cup shape measure (P <0.01, right eye; P <0.01, left eye), and mean RNFL thickness (P <0.01, right eye; P <0.01, left eye). A novel observation was temporal atrophy of the optic nerve head in CVI. CONCLUSIONS. The data provide a tridimensional, objective evaluation of the anatomic alterations of the optic nerve head in children with CVI. Furthermore, tomographic standards for optic disc shape in normal children are set for the first time.