7-year-old girl with isolated bilateral optic nerve hypoplasia (ONH). She has esotropia and nystagmus. Visual acuity is 20/200 in the right eye and 20/60 in the left eye. Bilateral small optic discs appear in color photographs. The ratio of the horizontal disc diameter (DD) to the distance between the macula and the temporal edge of the disc (DM)(DD/DM ratios) is less than 0.35. In addition to being small, the optic disc of the right eye is also pale.
Credit: M. Giray Ersoz, MD, FEBO
Biruni University School of Medicine, Department of Ophthalmology, Istanbul, Turkey
Instagram accounts: @retina.review and @retina.dr.girayersoz
Color Fundus Photography- OD
Color Fundus Photography- OS
Macular OCT scans and optic nerve head analysis show thin RNFL in both eyes.
ONH is characterized by decreased number of optic nerve axons. It can present unilaterally or bilaterally. It may present as an isolated anomaly or be associated with midline cerebral structural defects, such as septum pellucidum absence, agenesis of corpus callosum, cerebral hemisphere abnormalities, or pituitary gland abnormalities. The majority of patients with ONH have concurrent structural central nervous system abnormalities (90%) and neurodevelopmental disabilities.
Signs
The optic disc is often pale or gray and appears to be, at most, half the size of a normal optic disc. Optic discs usually have a double ring sign – a yellow-to-white ring around the disc. A ring of hypopigmentation or hyperpigmentation often surrounds the disc defining the area of the putative scleral canal. Tortuous retinal arterioles, venules, or both may accompany ONH, but retinal vessels can also present with normal caliber. DD/DM ratios less than 0.35 are generally indicative of ONH.
Symptoms
Visual acuity can range from normal to light perception. Most patients suffer from a visual acuity of 20/200 or worse. The visual field usually has localized defects combined with visual field constrictions, commonly in nasal or inferior fields. ONH can occur unilaterally, bilaterally symmetric, or bilaterally asymmetric. In unilateral and asymmetric bilateral ONH, relative afferent pupillary defects can be seen. Congenital sensory nystagmus often presents in bilateral ONH cases at 1-3 month of age, followed by strabismus development by 1 year of age, commonly esotropia.