A 17-year-old girl is brought to the clinic due to vision changes. Over the past 2 months, the patient has had difficulty seeing at night while driving. Last week, she was almost involved in a motor vehicle collision because she did not see a car approaching at an intersection. The patient is a strict vegan and eats a variety of plant products. She takes no daily medications. Temperature is 37.1 C (98.8 F). Visual acuity is 20/20 bilaterally. Bilateral lashes, conjunctivae, and cornea appear unremarkable. Pupils are equal and reactive, and extraocular muscles are intact. The patient has a visual field defect in the midperiphery in both eyes. Red reflex is equal bilaterally. Funduscopic examination reveals optic disc pallor and attenuation of retinal vessels with focal areas of discoloration bilaterally. Which of the following is the most likely cause for this patient's presentation?

Question

A 17-year-old girl is brought to the clinic due to vision changes.  Over the past 2 months, the patient has had difficulty seeing at night while driving.  Last week, she was almost involved in a motor vehicle collision because she did not see a car approaching at an intersection.  The patient is a strict vegan and eats a variety of plant products.  She takes no daily medications.  Temperature is 37.1 C (98.8 F).  Visual acuity is 20/20 bilaterally.  Bilateral lashes, conjunctivae, and cornea appear unremarkable.  Pupils are equal and reactive, and extraocular muscles are intact.  The patient has a visual field defect in the midperiphery in both eyes.  Red reflex is equal bilaterally.  Funduscopic examination reveals optic disc pallor and attenuation of retinal vessels with focal areas of discoloration bilaterally.  Which of the following is the most likely cause for this patient's presentation?

Quizplus · Accepted Answer

11ec25c8_d5df_97bf_bc81_f38f4e700b47_MD0003_00 This patient has characteristic findings of retinitis pigmentosa (RP), a genetic condition that causes progressive retinal degeneration. Although sporadic cases can occur, most patients have a family history of disease. Onset of RP varies, but most patients become symptomatic by early adulthood. Photoreceptor degeneration in RP begins with rods, which are located on the outer retina and are responsible for vision in dim lighting. Therefore, initial presentation typically includes night blindness and visual field defects, particularly in the midperiphery (ie, highest density of rods). Increasing clumsiness is common with progressive peripheral vision loss, and patients may notice flashing lights (photopsias) adjacent to blind spots (scotomas). In advanced disease, degeneration of cones (ie, photoreceptors on the central retina responsible for vision in bright light) leads to decreased visual acuity. Characteristic findings of RP on funduscopy include retinal vessel attenuation (ie, narrower vessels due to decreased retinal metabolic demand) and a waxy, pale optic disc (due to nerve gliosis and atrophy). In addition, degeneration of retinal pigment epithelium causes pigment deposition in a bone-spicule pattern (late finding). funduscopy Treatment generally involves measures to slow disease progression (eg, omega-3 fatty acids), but most patients are legally blind by age 40. (Choice A) Cataracts can present with difficulty driving at night due to visual impairment from headlight glare. However, decreased visual acuity, loss of red reflex, and lens opacification would be expected on examination. (Choice B) Open-angle glaucoma causes painless loss of peripheral vision but typically presents in late adulthood. In contrast to this case, funduscopic examination shows optic nerve cupping. optic nerve cupping (Choice C) Retinal detachment typically presents with acute vision loss, floaters, and flashes of light. Funduscopic examination shows a retinal tear and/or elevation, not seen in this case. (Choice E) Vitamin A deficiency causes xerophthalmia, characterized by excessive dryness of the cornea and conjunctivae and night blindness. This patient's cornea and conjunctivae appear normal. In addition, this patient eats a variety of vegetables, many of which contain vitamin A. Educational objective: Retinitis pigmentosa is a genetic condition resulting in progressive degeneration of the retina. Patients have progressive night blindness and peripheral vision loss. Funduscopic examination may show retinal pigment deposition in addition to retinal vessel attenuation and optic disc pallor. References: Retinitis pigmentosa. (http://www.ncbi.nlm.nih.gov/pubmed/30137803)

A 17-Year-Old Girl Is Brought to the Clinic Due to Vision