WBR0149
| Author | [[PageAuthor::Rim Halaby, M.D. [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry |
| Sub Category | SubCategory::General Principles |
| Prompt | [[Prompt::A 35-year-old female presents to her ophthalmologist for a decrease in vision. Over the past month she has experienced increasing difficulty distinguishing objects, especially when driving home from work at night. She denies any family history of ocular disease, reporting only hypertension in her father and dyslipidemia in her mother. Physical exam is unremarkable except for dry skin and fine hair. What is the most likely diagnosis?]] |
| Answer A | AnswerA::Diabetic retinopathy |
| Answer A Explanation | [[AnswerAExp::Diabetic retinopathy is the most severe retinal complication of diabetes. Up to 80% of all diabetics who have had diabetes for more than 18 years develop diabetic retinopathy. It is the leading cause of non-traumatic blindness in adults. People with untreated diabetes are 25 times more likely to develop blindness than the general population. However, this patient is young and neither her medical history nor her symptoms suggest the presence of diabetes.]] |
| Answer B | AnswerB::Glaucoma |
| Answer B Explanation | [[AnswerBExp::Glaucoma is a group of diseases of the optic nerve involving loss of retinal ganglion cells in a characteristic pattern. Although raised intraocular pressure is a significant risk factor for developing glaucoma, there is no established threshold intraocular pressure that causes glaucoma. One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressure for years and never develop damage. Untreated glaucoma leads to permanent damage of the optic nerve and resultant visual field loss, which can progress to blindness. This patient has no history of conditions such as ocular trauma or uveitis that would increase clinical suspicion for glaucoma.]] |
| Answer C | AnswerC::Cataract |
| Answer C Explanation | [[AnswerCExp::A cataract is an opacity that develops in the crystalline lens of the eye or in its envelope. Cataract can be caused by advanced age and diabetes among other causes. However, this patient is young and the history does not suggest the presence of cataract.]] |
| Answer D | AnswerD::Nutritional deficiency |
| Answer D Explanation | [[AnswerDExp::Night blindness is one of the first signs of vitamin A deficiency. Vitamin A deficiency is common in developing countries but rarely seen in developed countries.]] |
| Answer E | AnswerE::Genetic disease |
| Answer E Explanation | [[AnswerEExp::Genetic causes of blindness include: Leber's congenital amaurosis, Leber's hereditary optic neuropathy, retinoblastoma and albinism. This patient has no family history of blindness or albinism. Furthermore, she is older than the typical age of onset of all of the above conditions.]] |
| Right Answer | RightAnswer::D |
| Explanation | [[Explanation::Vitamin A deficiency is common in developing countries but rarely seen in developed countries. Night blindness is one of the first signs of vitamin A deficiency. Vitamin A deficiency is also associated with increased risk of infection, particularly measles, and with skin changes. Educational Objective: Vitamin A deficiency is associated with night blindness, skin changes and increased risk of measles. |
| Approved | Approved::No |
| Keyword | WBRKeyword::Eye, WBRKeyword::Opthalmology, WBRKeyword::Blindness, WBRKeyword::Vitamin, WBRKeyword::Nutrition, WBRKeyword::Vision loss |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |