A 35-year-old man from Delhi presents with complaints of blurred vision at all distances and frequent headaches. He reports that his vision is clearer when he squints or tilts his head. On slit-lamp examination, the cornea appears clear with no scarring. Keratometry shows corneal curvature of 44.00 D in the horizontal meridian and 47.50 D in the vertical meridian. Retinoscopy confirms myopic astigmatism. The patient's uncorrected visual acuity is 6/18 in both eyes. Which of the following is the most appropriate initial management?

Explanation

## Clinical Analysis **Keratometry Findings:** - Horizontal meridian: 44.00 D (flatter) - Vertical meridian: 47.50 D (steeper) - Difference: 3.50 D of astigmatism The steeper vertical meridian (47.50 D) indicates that the vertical meridian is more myopic in **myopic astigmatism**. The cylindrical lens must be placed along the steeper meridian to correct the refractive error. ## Key Point: **In myopic astigmatism**, the cylindrical lens is placed along the steeper (more myopic) meridian. Here, the vertical meridian is steeper, so the cylinder axis is **90°** (vertical). ## High-Yield: **Correction of Astigmatism:** - Cylinder axis is always placed along the **steeper meridian** - In myopic astigmatism: steeper meridian is more myopic → cylinder corrects that meridian - In hyperopic astigmatism: steeper meridian is more hyperopic → cylinder corrects that meridian ## Clinical Pearl: The patient's symptom of **clearer vision on squinting** is classic for astigmatism — squinting creates a pinhole effect that reduces the blur from astigmatism by limiting the cone of light entering the eye. ## Management Algorithm: ```mermaid flowchart TD A[Astigmatism diagnosed on keratometry]:::outcome --> B{Magnitude of astigmatism?}:::decision B -->|< 0.5 D| C[No correction needed]:::action B -->|0.5–3.0 D| D[Spectacle correction]:::action B -->|> 3.0 D| E{Patient tolerance?}:::decision E -->|Good| D E -->|Poor| F[RGP contact lens or refractive surgery]:::action D --> G[Cylinder placed on steeper meridian]:::action ``` [cite:Parson's Diseases of the Eye 21e Ch 3]