A 58-year-old man comes to the office with reports of visual disturbances over the past several weeks. He describes multiple episodes of bluish tinting of his vision and a sensation of "lights becoming too bright," which last a few hours and improve spontaneously. He has had no headache, eye pain, loss of vision, tunnel vision, focal weakness, or numbness. The patient has a history of type 2 diabetes mellitus, hypertension, stage 3 chronic kidney disease, and erectile dysfunction. His medications include lisinopril, amlodipine, furosemide, insulin detemir, and as-needed sildenafil. He does not use tobacco, alcohol, or recreational drugs.
Blood pressure is 120/70 mm Hg and pulse is 76/min. The patient's pupils are equal and reactive, and visual acuity and field of vision are normal. Funduscopy shows few microaneurysms and dot-blot hemorrhages but is otherwise unremarkable. Neurological examination demonstrates decreased pain sensation over both feet and bilateral absence of ankle reflexes but is otherwise unremarkable.
Which of the following is the most likely cause of this patient's current visual symptoms?

Question

A 58-year-old man comes to the office with reports of visual disturbances over the past several weeks.  He describes multiple episodes of bluish tinting of his vision and a sensation of "lights becoming too bright," which last a few hours and improve spontaneously.  He has had no headache, eye pain, loss of vision, tunnel vision, focal weakness, or numbness.  The patient has a history of type 2 diabetes mellitus, hypertension, stage 3 chronic kidney disease, and erectile dysfunction.  His medications include lisinopril, amlodipine, furosemide, insulin detemir, and as-needed sildenafil.  He does not use tobacco, alcohol, or recreational drugs.
Blood pressure is 120/70 mm Hg and pulse is 76/min.  The patient's pupils are equal and reactive, and visual acuity and field of vision are normal.  Funduscopy shows few microaneurysms and dot-blot hemorrhages but is otherwise unremarkable.  Neurological examination demonstrates decreased pain sensation over both feet and bilateral absence of ankle reflexes but is otherwise unremarkable.
Which of the following is the most likely cause of this patient's current visual symptoms?

Quizplus · Accepted Answer

11ec193a_9896_7ed2_853d_3b8b461ee037_MD0002_00 Phosphodiesterase-5 (PDE-5) inhibitors prevent the breakdown of cyclic guanosine monophosphate in the corpus cavernosum, resulting in prolonged vasodilation and penile erection. However, PDE-5 inhibitors also interact with phosphodiesterase-6, which is required for normal functioning of rods and cones in the retina. Dose-dependent, temporary visual side effects such as bluish tinting, blurry vision, and photophobia occur in up to 3% of patients taking sildenafil, but occur much less frequently with other PDE-5 inhibitors. (Choice A) Early changes of diabetic retinopathy (microaneurysm and dot-blot hemorrhage) are common with prolonged history of uncontrolled diabetes mellitus and are associated with blurry vision, floaters, or painless loss of vision. However, diabetic retinopathy does not cause transient bluish tinting or photophobia. (Choice B) Age-related macular degeneration (AMD) results in painless loss of vision, which usually presents initially as tunnel vision. Yellow or white drusen (dry AMD) or retinal hemorrhages and gray discoloration (wet AMD) are typically seen on funduscopy. (Choice D) Unlike angle-closure glaucoma, open-angle glaucoma is generally asymptomatic and cupping is seen in the fundus. (Choice E) Transient ischemic attacks can cause temporary vision loss or disturbance (amaurosis fugax) but are not associated with changes in color vision or photophobia. Educational objective: Phosphodiesterase-5 (PDE-5) inhibitors prevent the breakdown of cyclic guanosine monophosphate in the corpus cavernosum. However, PDE-5 inhibitors also interact with phosphodiesterase-6 in the retina and can result in dose-dependent, temporary visual side effects such as bluish tinting, blurry vision, and photophobia. __________ References: Ocular safety of Viagra, (sildenafil citrate). (http://www.ncbi.nlm.nih.gov/pubmed/10703120)

A 58-Year-Old Man Comes to the Office with Reports of Visual