A 25 year old lady presents with a unilateral cataract. There is no history of trauma, pain, redness of eyes or steroid usage. What is the likely cause?
**Core Concept**
The development of a unilateral cataract in a young adult without any history of trauma, pain, redness, or steroid usage suggests a possible congenital or genetic etiology. Cataracts can be classified into several types, including congenital, developmental, and secondary cataracts, which are often associated with systemic or metabolic disorders.
**Why the Correct Answer is Right**
The most common cause of a unilateral cataract in a young adult is a congenital or developmental cataract. Congenital cataracts are present at birth, while developmental cataracts appear during the first few years of life. These types of cataracts can be caused by genetic mutations, intrauterine infections, or other prenatal factors. In the case of a unilateral cataract, the underlying cause is often related to an intrauterine or perinatal insult that affects the lens development.
**Why Each Wrong Option is Incorrect**
**Option A:** This option might suggest a posterior subcapsular cataract, which is often associated with steroid use or certain medications. However, the patient has no history of steroid usage or similar factors.
**Option B:** This option could imply a traumatic cataract, which is often associated with pain, redness, or other signs of ocular trauma. However, the patient has no history of trauma.
**Option C:** This option might suggest a diabetic cataract, which is often associated with chronic diabetes mellitus. However, there is no information in the question stem suggesting the patient has diabetes.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that congenital and developmental cataracts can be associated with systemic or metabolic disorders, such as Down syndrome, galactosemia, or other genetic conditions.
**Correct Answer:** C.