A 17-year-old boy is brought to the clinic due to poor vision at night. The patient developed mild difficulty seeing at night about 4 months ago, and it has slowly worsened. Visual field examination shows visual loss in the midperiphery. External eye examination reveals normal tear formation. Funduscopic examination shows bilateral optic disc pallor, attenuation of retinal vessels, and areas of dark discoloration in the retina. Which of the following is the most likely mechanism of this patient's visual impairment?

Question

A 17-year-old boy is brought to the clinic due to poor vision at night.  The patient developed mild difficulty seeing at night about 4 months ago, and it has slowly worsened.  Visual field examination shows visual loss in the midperiphery.  External eye examination reveals normal tear formation.  Funduscopic examination shows bilateral optic disc pallor, attenuation of retinal vessels, and areas of dark discoloration in the retina.  Which of the following is the most likely mechanism of this patient's visual impairment?

Quizplus · Accepted Answer

Eductional Objective: Retinitis pigmentosa is a genetic condition resulting in progressive dystrophy of retinal pigmented epithelium and photoreceptors.  Patients typically present with progressive night blindness and loss of peripheral vision due to early loss of rods, which are highly metabolically active.  Funduscopic examination may show dark pigments deposited in a bone-spicule pattern in addition to retinal vessel attenuation and optic disc pallor.

A 17-Year-Old Boy Is Brought to the Clinic Due to Poor