**Core Concept**
Rider's cataract is a type of posterior subcapsular cataract (PSC) that is associated with the use of corticosteroids, particularly topical or systemic corticosteroid therapy. It is characterized by the formation of cataractous changes in the posterior subcapsular region of the lens, which can lead to vision impairment.

**Why the Correct Answer is Right**
The development of Rider's cataract is thought to be related to the inhibitory effects of corticosteroids on the synthesis of proteins in the lens, leading to a disruption in the normal metabolic processes of the lens epithelial cells. This disruption can cause the formation of cataractous changes in the posterior subcapsular region of the lens. The use of corticosteroids, particularly in high doses or for prolonged periods, increases the risk of developing Rider's cataract.

**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because Rider's cataract is not typically associated with diabetes mellitus. While diabetes can cause cataracts, it is usually associated with other types of cataracts, such as snowflake cataracts or cortical cataracts.
* **Option B:** Incorrect because Rider's cataract is not typically associated with age-related changes. While age-related changes can cause cataracts, Rider's cataract is specifically associated with corticosteroid use.
* **Option C:** Incorrect because Rider's cataract is not typically associated with trauma to the eye. While trauma can cause cataracts, it is usually associated with other types of cataracts, such as posterior polar cataracts or traumatic cataracts.

**Clinical Pearl / High-Yield Fact**
It is essential for clinicians to be aware of the potential for corticosteroid-induced cataracts, particularly in patients receiving long-term corticosteroid therapy. Regular eye examinations and monitoring for cataract development are crucial in preventing vision impairment.

**Correct Answer: D. Corticosteroid use.**