Vision Physiology — Retina and Pathway

Which feature best distinguishes rod photoreceptors from cone photoreceptors in the human retina?

A 28-year-old woman with a family history of progressive night blindness and peripheral vision loss presents with nyctalopia and constricted visual fields. Fundoscopy shows bone-spicule pigmentation and waxy optic disc pallor. Which investigation would best confirm the diagnosis of retinitis pigmentosa?

A 42-year-old woman from Delhi presents with progressive night blindness over 3 months, followed by progressive loss of peripheral vision while central vision remains intact. On examination, visual acuity is 6/6 but confrontation testing reveals a concentric visual field defect. Fundoscopy shows bone spicule-like pigmentation in the peripheral retina with optic disc pallor. Which photoreceptor type is primarily affected in this condition?

A 58-year-old man with hypertension presents with sudden loss of the superior half of the visual field in his right eye. Which is the most common site of lesion in the optic pathway?

A 52-year-old man presents with progressive loss of central vision and metamorphopsia. Fundoscopy reveals drusen and retinal pigment epithelium changes in the macula. Which investigation is most appropriate to confirm the diagnosis and assess disease severity?