Optical coherence tomography angiography (OCTA) is a new non-invasive imaging technique that does not require the use of contrast agents and that allows the visualization of the retinal microvasculature in a layer-by-layer manner without bright light. This merit allows us to obtain the fundus image in children. Retinal vessels are typically absent from the center of the fovea, an area known as the foveal avascular zone (FAZ). The purpose of the present case study was to evaluate the FAZ in a nanophthalmic pediatric patient with OCTA. A 6-year-old girl was referred to the Hiroshima University Hospital because of her poor vision. She had a best-corrected visual acuity of 20/125 in the right eye and of 20/100 in the left eye. The refractive errors after the administration of atropine sulfate eye drops were +13.00D in the right eye and +14.00D in the left eye. The axial lengths were 17.03 mm in the right eye and 16.90 mm in the left eye. At 9 years of age, the patient was diagnosed with nanophthalmos and OCTA was used to investigate the superficial and deep retinal layers. We demonstrated that the FAZ could not be observed in either eye, whereas the FAZ was readily observed in both eyes of a control subject of similar age. OCTA is a useful technique to reveal the absence of the FAZ in cases of nanophthalmos. Because OCTA is a non-invasive and rapid procedure that is ideal for use with children.