Ectopia lentis is seen in all of the following except: March 2007
**Core Concept**
Ectopia lentis refers to the displacement or malposition of the lens in the eye, which can be due to various congenital or acquired conditions affecting the lens or the surrounding ocular structures. This condition can lead to vision impairment and is often associated with other systemic diseases.
**Why the Correct Answer is Right**
Ectopia lentis is commonly seen in Marfan syndrome, a genetic disorder affecting the connective tissue, which can cause lens subluxation due to the weakening of the zonular fibers that suspend the lens. It is also associated with Weil's disease (leptospirosis), a bacterial infection that can cause uveitis and lens inflammation, leading to lens displacement. Additionally, trauma to the eye can also cause ectopia lentis. However, it is not typically associated with **Option A:** Homocystinuria, a genetic disorder characterized by elevated levels of homocysteine in the blood, which can lead to lens dislocation, but it is not a common cause of ectopia lentis compared to the other options listed.
**Why Each Wrong Option is Incorrect**
* **Option A:** Homocystinuria is not a common cause of ectopia lentis compared to the other options listed, although it can lead to lens dislocation.
* **Option C:** Trauma to the eye is a known cause of ectopia lentis, and it is often associated with other ocular injuries.
* **Option D:** Weil's disease (leptospirosis) is a bacterial infection that can cause lens inflammation and displacement, making it a valid association with ectopia lentis.
**Clinical Pearl / High-Yield Fact**
Remember the "MARFAN" acronym to associate ectopia lentis with Marfan syndrome: M - Microcornea, A - Axial myopia, R - Retinal detachment, F - Floater, A - Anterior chamber shallowing, and N - Nuclear cataract.
**Correct Answer: D. Weil's disease (leptospirosis) is not a correct answer for ectopia lentis, though the question asks for an exception. The correct answer is actually: C. Trauma**