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An 82-year-old woman reports vision changes in her right eye that have developed gradually over the past several months. She needs significantly brighter light when sewing, reading, and doing other close work. She has also experienced “gaps” in visual images— blank spaces and blind spots in the center of things she looks at; at times she has difficulty in recognizing faces. Her left eye seems unaffected. She fears that she has had a stroke, although she has no speech difficulty, extremity weakness, abnormal sensory sensations (such as numbness or tingling), or any other neurological symptoms.
HISTORY
Her health is good for her age. She has not required hospitalization since a cholecystectomy 12 years earlier. She has mild essential hypertension that is well controlled with a low-dose angiotensin-converting enzyme inhibitor. She also takes a multivitamin supplement daily.
Several random blood glucose levels greater than 120 mg/dL have been documented; however, her hemoglobin A1c level has always been normal, and no treatment other than reduced intake of sweets has been needed. She has no history of congestive heart failure, chronic obstructive pulmonary disease, or cancer, and a review of systems reveals no evidence of these entities.
PHYSICAL EXAMINATION
Heart rate is 80 beats per minute and regular; blood pressure is 115/76 mm Hg. Head, ears, eyes, nose, and throat are normal; no neck bruits are noted. Chest is clear. A soft grade 1/6 ejection murmur is audible along the left sternal border. There is no organomegaly and no abdominal masses. A careful neurological examination reveals cranial nerves II through XII to be grossly intact. The patient has good and equal strength in all 4 extremities. Sensation and cerebellar function are intact, and all reflexes are normal.
LABORATORY AND IMAGING RESULTS
A routine hemogram is normal. Results of a chemistry profile are also normal, with a random blood glucose level of 115 mg/dL. A complete examination by an ophthalmologist has been scheduled for later in the day; a CT scan of the brain has also been scheduled.
Which of the following statements about the cause of this patient’s vision changes is false? |
