**Core Concept**
Disciform herpetic keratitis is a type of corneal inflammation caused by herpes simplex virus (HSV) infection. It involves the deep layers of the cornea, leading to a characteristic disc-shaped lesion.

**Why the Correct Answer is Right**
Disciform herpetic keratitis occurs when HSV infects the corneal endothelium, causing inflammation and necrosis of the corneal stroma. This leads to the formation of a disc-shaped lesion, often accompanied by corneal edema and vision loss. The immune response to the virus triggers the release of pro-inflammatory cytokines, which further exacerbate the inflammatory response.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it doesn't specify the involvement of HSV in the pathogenesis of disciform herpetic keratitis.
**Option B:** This option is incorrect because it doesn't accurately describe the characteristic disc-shaped lesion associated with disciform herpetic keratitis.
**Option C:** This option is incorrect because it doesn't mention the involvement of the corneal endothelium in the pathogenesis of disciform herpetic keratitis.

**Clinical Pearl / High-Yield Fact**
It's essential to recognize the characteristic disc-shaped lesion and corneal edema associated with disciform herpetic keratitis, as prompt diagnosis and treatment can help prevent vision loss.

**Correct Answer: D. Involvement of the corneal endothelium by herpes simplex virus (HSV) infection.**