Commonest type of cataract is:
**Core Concept**
Cataracts are a leading cause of vision loss worldwide, and they can be classified into various types based on their location, shape, and other characteristics. The most common type of cataract is a nuclear cataract, which affects the central part of the lens.
**Why the Correct Answer is Right**
Nuclear cataracts are the most common type of cataract due to the gradual accumulation of yellow-brown pigment and hardening of the lens nucleus over time. This process is associated with aging and is more common in individuals with a family history of cataracts or those who have been exposed to UV radiation. The accumulation of pigment and hardening of the lens nucleus can lead to a decrease in the lens's ability to focus light, causing blurred vision and other symptoms.
**Why Each Wrong Option is Incorrect**
* **Option A:** Cortical cataracts are characterized by white, wedge-shaped opacities that start in the periphery of the lens and work their way towards the center. They are more common in individuals with diabetes or those who have had previous eye injuries.
* **Option B:** Posterior subcapsular cataracts (PSC) are a type of cataract that affects the back of the lens and can cause vision problems even at an early stage. However, they are less common than nuclear cataracts.
* **Option C:** Congenital cataracts are present at birth and can be caused by genetic factors or other conditions. They are relatively rare compared to nuclear cataracts.
**Clinical Pearl / High-Yield Fact**
It's essential to note that the type of cataract can affect the treatment options and surgical approaches. Nuclear cataracts often require more complex surgical procedures, such as phacoemulsification or extracapsular cataract extraction.
**Correct Answer:** C. Nuclear cataract.