A 22-year-old male presents to the ophthalmology clinic with progressive blurring of vision and frequent changes in spectacle prescription over the past 18 months. He reports rubbing his eyes vigorously due to chronic allergic conjunctivitis. On examination, visual acuity is 6/36 in both eyes. Slit-lamp examination reveals a conical protrusion of the cornea with stromal thinning at the apex. Keratometry shows irregular astigmatism with a difference of >1.5 D between the two meridians. What is the most appropriate next step in management?

Explanation

## Clinical Presentation & Diagnosis This patient presents with classic features of **keratoconus**: - Progressive myopia and astigmatism with frequent refractive changes - Conical corneal protrusion on slit-lamp examination - Stromal thinning at the apex - Irregular astigmatism (>1.5 D difference between meridians) - History of eye rubbing (major risk factor) ## Management Strategy for Keratoconus **Key Point:** Management depends on the stage of disease and visual potential. Early-to-moderate keratoconus with reasonable visual acuity is managed conservatively; advanced disease with significant visual loss may require surgical intervention. ### Stages & Management Approach | Stage | Characteristics | Management | |-------|-----------------|-------------| | Early | VA 6/6–6/18, minimal corneal scarring | Spectacles, RGP lenses | | Moderate | VA 6/18–6/60, irregular astigmatism | RGP contact lenses, cross-linking | | Advanced | VA <6/60, corneal scarring, hydrops | Cross-linking, PK if scarred | ## Why RGP Contact Lenses Are First-Line Here **High-Yield:** Rigid gas-permeable (RGP) contact lenses are the **gold standard for visual rehabilitation** in early-to-moderate keratoconus because they: 1. Vault over the irregular corneal surface, providing a regular refracting surface 2. Restore visual acuity to near-normal levels (often 6/9 or better) 3. Are non-invasive and reversible 4. Allow disease monitoring without surgical commitment **Clinical Pearl:** In this patient, VA is 6/36 with glasses but will likely improve significantly with RGP lenses due to correction of irregular astigmatism. ## Why Corneal Cross-Linking? Corneal cross-linking (CXL) with riboflavin and UV-A is indicated to **halt disease progression** and is increasingly used in moderate keratoconus, but it does not restore vision—it stabilizes the cornea. It is often combined with RGP lenses for optimal outcomes in progressive disease. ## Why Not PK at This Stage? Penetrating keratoplasty is reserved for **advanced keratoconus with: - Significant corneal scarring - Acute hydrops with persistent edema - Intolerance to contact lenses despite optimization - VA <6/60 unresponsive to other measures This patient is not yet at that threshold. ## Why Not PRK? PRK and LASIK are **contraindicated** in keratoconus because ablation of already-thin corneal tissue accelerates ectasia and disease progression.