A 76-year-old woman comes to the physician because of a 6-month history of progressive difficulty reading and recognizing faces. She reports that while her peripheral vision seems fine, the center of her vision is "blurry and distorted." She notes that straight lines, such as the edges of a doorway, appear "wavy." She has a 40-pack-year smoking history but quit 10 years ago. On physical examination, visual acuity is 20/100 in both eyes. Amsler grid testing shows distortion of the central grid lines. Funduscopic examination reveals numerous small, yellow-white deposits in the subretinal space and areas of retinal pigment epithelial atrophy.
Which of the following is the most likely diagnosis?
The correct answer is:
A) Age-related macular degeneration
This patient is presenting with the classic features of age-related macular degeneration (AMD), specifically the dry (atrophic) type. AMD is the leading cause of permanent blindness in the elderly in developed countries. It presents with gradual loss of central vision, which is needed for reading and recognizing faces, and distortion of straight lines. The presence of drusen (yellow-white deposits) and pigmentary changes on fundoscopy confirms the diagnosis. Smoking is the most significant modifiable risk factor.
Answer choice B: Cataracts, is incorrect. Cataracts cause a gradual, painless blurring of vision and increased glare, especially at night. However, cataracts typically cause a generalized decrease in vision rather than specific central distortion or distortion of straight lines.
Answer choice C: Diabetic retinopathy, is incorrect. While diabetic retinopathy can lead to macular edema and central vision loss, the fundoscopic findings typically include microaneurysms, dot-and-blot hemorrhages, and hard exudates. This patient has no history of diabetes and shows classic drusen.
Answer choice D: Open-angle glaucoma, is incorrect. Glaucoma is characterized by a gradual loss of peripheral vision (tunnel vision) due to optic nerve damage. Central vision is usually preserved until the very late stages of the disease, which is the opposite of this patient's presentation.
Answer choice E: Retinal detachment, is incorrect. Retinal detachment is usually an acute event presenting with flashes, floaters, and a "curtain" of vision loss, rather than a slow, 6-month progression of central blurring.
Key Learning Point
Age-related macular degeneration (AMD) is a leading cause of central vision loss in the elderly. Metamorphopsia (distorted straight lines) is a hallmark symptom, often assessed with an Amsler grid. Drusen are the classic funduscopic finding in dry AMD, whereas wet AMD involves neovascularization and subretinal fluid/hemorrhage.
