Characteristics of visual functioning in individuals with propionic acidemia

Propionic acidemia is a rare autosomal recessive metabolic disorder caused by a deficiency of the enzyme propionyl-CoA carboxylase, leading to the accumulation of toxic levels of propionic acid in the blood. This accumulation can result in life-threatening metabolic crises and a wide range of systemic and neurological complications. In individuals with propionic acidemia, recurrent metabolic decompensations, altered neurological status, developmental delays, and psychomotor retardation are commonly observed, with significant variability in their clinical presentation. Visual impairment in propionic acidemia may arise due to the impact of these associated systemic and neurological disturbances on the optic nerve, visual pathways, and cortical visual processing areas, potentially leading to cerebral visual impairment. This case study presents the visual functioning of a seven-year-old girl with a confirmed diagnosis of propionic acidemia. It highlights her specific visual profile and describes individually designed adaptations that support visual access and processing. Observations over time in different settings revealed patterns such as delayed visual responses, fluctuations in visual performance depending on the time of day, color preferences, difficulties in object recognition within visually cluttered scenes, and stronger responses to moving versus static visual stimuli. Based on these findings, a targeted visual stimulation and (re)habilitation program was created, along with an individualised adaptation plan to enhance visual learning and interaction with the environment.