Okay, let's tackle this question about keratoconus. First, I need to remember what keratoconus actually is. It's a corneal disorder where the cornea thins and bulges into a cone shape, leading to visual distortion. The question is asking which statement is true about it.

The correct answer is probably related to the pathophysiology or diagnostic features. Let's think about the options. Common facts about keratoconus include that it's associated with a history of eye rubbing, which can exacerbate the condition. Also, corneal topography is the gold standard for diagnosis. Another point is that it usually presents asymmetrically and can lead to irregular astigmatism.

Wait, the options aren't listed here, but I have to assume standard distractors. For example, options might mention treatment with cross-linking, association with allergies, or progression patterns. Let's say the correct answer is D: "Diagnosis is confirmed by corneal topography." That makes sense because topography is the key diagnostic tool.

Now, why are other options wrong? If an option says it's hereditary, that's partially true but not the main diagnostic method. Another option might suggest surgical correction as primary treatment, but cross-linking is more common early on. Another might misstate the age of onset, but keratoconus typically starts in adolescence.

The clinical pearl here is that corneal topography is essential for early detection and monitoring. Also, patients with keratoconus often have associated allergic conditions like vernal keratoconjunctivitis, so that's another point.

Putting it all together, the correct answer would be the one stating that corneal topography is the diagnostic method. The explanation should cover why topography is the gold standard, and why other options are incorrect based on other aspects like treatment or associated conditions.

**Core Concept**
Keratoconus is a non-inflammatory corneal ectasia characterized by progressive thinning and conical protrusion of the cornea, leading to irregular astigmatism and visual distortion. Diagnosis relies on corneal topography to detect characteristic patterns like inferior steepening and Fleischer rings.

**Why the Correct Answer is Right**
**Option D** is correct because **corneal topography** is the gold standard for diagnosing keratoconus. It identifies subtle corneal irregularities, asymmetric thinning, and conical morphology before significant visual symptoms develop. Early detection via topography allows timely interventions like corneal cross-linking to halt progression.

**Why Each Wrong Option is Incorrect**
**Option A:** "Caused by bacterial infection" is incorrect. Keratoconus is a structural degenerative disorder, not infectious.
**Option B:** "Treated primarily with cataract surgery" is incorrect. Cataract surgery is irrelevant; keratoconus is managed with rigid contact lenses, cross-linking, or, in advanced cases, corneal transplantation.
**Option C:** "Always bilateral and symmetrical" is incorrect. Keratoconus is typically asymmetric and unilateral in early stages.

**Clinical Pearl / High-Yield Fact**
Keratoconus commonly presents in adolescence and is associated with **allergic conditions** (e.g., vernal keratoconjunctivitis) and **eye rubbing**. Corneal cross-link

✓ Correct Answer: A. Progressive thickening of sclera