Purpose To study the relationship between macular ganglion cell complex (GCC) thickness and visual field defects (VFD) caused by central nervous system (CNS) lesions in children and evaluate the possibility of predicting VFD according to GCC maps. Methods The GCC maps of a group of children with VFD due to CNS lesions with respect of the vertical meridian in at least one eye (study group), as well as of children with other neuro-ophthalmological problems and healthy children were presented to two masked evaluators, who were asked to predict the patients' VFD on the basis of GCC damage: the evaluators classified VFD as normal, hemianopia (homonymous or heteronymous) or diffuse. Results Seventeen patients were included in the study group, with a median age of 12 years. Fifteen had brain tumours and two epilepsy. The mean MD of the affected hemifields was -26.00 dB (SD 7.89 dB) versus -5.51 dB (SD 3.52 dB) for the nonaffected hemifields,p < 0.001. The mean GCC thickness was of 56.04 mu m (SD 11.95 mu m) in the affected hemiretinas versus 74.31 mu m (SD 10.64 mu m) for the non-affected,p < 0.001. Kappa coefficients between VFD and those estimated by the evaluators were 0.705 and 0.658 (p < 0.001) for evaluators 1 and 2. Conclusions GCC thickness can reflect damage to the visual pathway and GCC maps may be useful to identify chiasmal and retrochiasmal lesions, since GCC atrophy in most of these cases respects the vertical meridian. GCC maps might be used as a surrogate marker for visual damage in patients unable to perform perimetry.