A 58-year-old man comes to the emergency department due to vision disturbances. Over the past several weeks, the patient has had intermittent episodes in which he sees everything tinted with blue. His vision returned to normal within a few hours each time. When he woke up today, vision in the left eye was blurry. He has had no eye pain, conjunctival redness, or headache. The patient has tingling and numbness in the feet due to diabetic neuropathy, which is unchanged, and reports no other focal weakness or sensory loss. Medical history is notable for hypertension, type 2 diabetes mellitus, hyperlipidemia, and erectile dysfunction. Vital signs are within normal limits. Physical examination shows an afferent pupillary defect, decreased visual acuity, and optic disc edema in the left eye. Discontinuing which of the following medications may improve this patient's vision?

Question

A 58-year-old man comes to the emergency department due to vision disturbances.  Over the past several weeks, the patient has had intermittent episodes in which he sees everything tinted with blue.  His vision returned to normal within a few hours each time.  When he woke up today, vision in the left eye was blurry.  He has had no eye pain, conjunctival redness, or headache.  The patient has tingling and numbness in the feet due to diabetic neuropathy, which is unchanged, and reports no other focal weakness or sensory loss.  Medical history is notable for hypertension, type 2 diabetes mellitus, hyperlipidemia, and erectile dysfunction.  Vital signs are within normal limits.  Physical examination shows an afferent pupillary defect, decreased visual acuity, and optic disc edema in the left eye.  Discontinuing which of the following medications may improve this patient's vision?

Quizplus · Accepted Answer

11ec160b_3c24_ab1d_9249_3f3395ec9140_MD0001_00 Normal male erectile function involves interplay between psychological and physical stimulation and the vascular, neurologic, and hormonal systems. On a vascular level, penile erection is induced by increased blood flow to the corpora cavernosa and corpus spongiosum accompanied by decreased outflow. Endothelial factors required for erection include formation of nitric oxide, which induces formation of cyclic GMP (cGMP), which in turn mediates vascular smooth muscle relaxation. cGMP is inactivated by cGMP phosphodiesterase (PDE) (ie, PDE5), which cleaves cGMP and terminates penile erection. PDE5 inhibitors (eg, sildenafil, tadalafil) are widely used, first-line agents for treatment of erectile dysfunction (ED). PDE5 inhibitors increase activity of cGMP in the penile corpora, leading to greater and more prolonged tumescence in men with ED. However, PDE5 inhibitors can also inhibit PDE6 in the retina, which is involved in color vision. Patients experience this effect as a transient bluish discoloration to vision. Less common ocular effects of PDE5 inhibitors include nonarteritic anterior ischemic optic neuropathy, which presents with sudden monocular vision loss associated with an afferent pupillary defect, decreased visual acuity, and optic disc edema. (Choice A) The anticholinergic effects of tricyclic antidepressants (eg, amitriptyline) can cause dry eye, blurred vision, and triggering of angle-closure glaucoma (ie, ocular pain, headache, unilateral vision loss). Discoloration of vision is not typical. (Choice B) Important side effects of statins (eg, atorvastatin) include myopathy and hepatic toxicity. Statins may have a small effect on the risk of cataract but otherwise have few ocular manifestations. (Choice C) Sodium-glucose cotransporter 2 inhibitors (eg, canagliflozin) induce increased renal excretion of glucose and water. Most of the side effects (eg, hypotension, urinary tract infection) are related to glucosuria and fluid shifts; visual symptoms are not common. (Choice D) Metformin most commonly causes gastrointestinal side effects (eg, nausea, diarrhea). Lactic acidosis is a potentially serious but rare complication. Visual side effects are not a significant concern. (Choice E) Side effects of ACE inhibitors (eg, ramipril) are primarily related to renal function (eg, hyperkalemia, acute kidney injury) or blood pressure (eg, dizziness, hypotension). Patients may also develop a dry cough due to an increase in circulating bradykinin. Educational objective: Phosphodiesterase 5 inhibitors (eg, sildenafil, tadalafil) can cause a transient bluish discoloration to vision. Less common ocular effects include sudden monocular vision loss due to nonarteritic anterior ischemic optic neuropathy; findings include an afferent pupillary defect, decreased visual acuity, and optic disc edema. __________ References: Acute nonarteritic anterior ischemic optic neuropathy and exposure to phosphodiesterase type 5 inhibitors. (http://www.ncbi.nlm.nih.gov/pubmed/25358826)

A 58-Year-Old Man Comes to the Emergency Department Due to Vision