**Core Concept**
Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae that can affect various organs, including the eyes. The ophthalmic manifestations of diphtheria are a result of the toxin produced by the bacteria, which can lead to tissue damage and cellular necrosis.

**Why the Correct Answer is Right**
The toxin produced by Corynebacterium diphtheriae, known as diphtheria toxin, causes the most common ophthalmic affection of diphtheria. The toxin works by inhibiting protein synthesis in host cells, leading to cell death and tissue damage. This can result in conjunctivitis, keratitis, and even corneal ulcers. The toxin's effect on the eyes is a result of its ability to bind to and inactivate elongation factor-2 (EF-2), a critical protein involved in protein synthesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the most common ophthalmic affection of diphtheria.
**Option B:** This option is incorrect because it is not a recognized ophthalmic manifestation of diphtheria.
**Option D:** This option is incorrect because it is not the most common ophthalmic affection of diphtheria.

**Clinical Pearl / High-Yield Fact**
Diphtheria toxin can also cause myocarditis and neuropathy in addition to its ophthalmic manifestations. It is essential to diagnose and treat diphtheria promptly to prevent long-term complications.

**Correct Answer:** B. Toxic epidermal necrolysis (TEN) is not the correct answer. The correct answer is actually **B. Toxic Epitheliopathy** but in the context of diphtheria, the most common ophthalmic affection is actually **B. Toxic Epitheliopathy** or more commonly known as **B. Toxocellular Epitheliopathy**