Optic nerve hypoplasia - Clinical profile and co-relation with vision and neuro-radiological features

To study the features and co-relation of optic nerve hypoplasia (ONH) with severity of visual impairment and associated neuro-radiologic features.

Of 297 ONH medical records screened, 57 patients with photographic documentation of the optic nerves and magnetic resonance imaging (MRI) of the brain and orbits were included in the study. Patient demographics, vision, ocular examination findings, and optic disc photographs for disc diameter: macula distance (DD: DM), size of the disc, and double ring size along with MRI were analyzed by a single observer. The disc to macula ratio was used to grade ONH as <3 as partial/mild ONH, 3.12-4 as complete ONH, and >4.12 severe ONH.

The mean age at presentation was 11.38 (±8.87) years. The best corrected visual acuity in the better eye ranged from 20/20 (n = 2; 3.5%) to severe to profound vision loss (<20/200 - no light perception) (n = 25; 43.85%). Optic disc findings suggestive of mild ONH in n= 31eyes (39.2%); and severe in n =17eyes (21.5%). Bilateral ONH was noted in 22 patients (38.6%), and unilateral was noted in 35 patients (59.65%). Neuroimaging findings were reported normal (n = 10, 17.54%), absent septum pellucidum and corpus callosal thinning (n = 19, 33.33%), and chiasmal atrophy (n = 9, 15.8%). Correlation analysis confirmed that as the DD: DM distance increases, poorer vision and abnormal neuro-imaging findings were noted.

Severity of ONH as indicated by DD: DM ratio is a surrogate indicator of neuro-radiological abnormalities and poor vision. Neuro-imaging and a multidisciplinary approach are warranted.