A child age 5 years presents with loss of vision and mild proptosis of left eye. On examination direct reflex is absent but consensual reflex is present in left eye. He is having:

Gliomas of the anterior visual pathway, more commonly arising in the optic nerve. About 70% of cases present before the age of 7 years, with visual loss, proptosis, strabismus, or nystagmus. The initial symptoms are dimness of vision with constricted fields, followed by bilateral field defects of homonymous, heteronymous, and sometimes bitemporal type and progressing to blindness and optic atrophy with or without papilledema. Visual field defects reveal an optic nerve or chiasmal syndrome. Ref: Riordan-Eva P., Hoyt W.F. (2011). Chapter 14. Neuro-Ophthalmology. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.