Makindo Medical Notes

👁️ In astigmatism, the cornea or lens is curved more in one direction than another, leading to blurred or distorted vision. Regular eye checks 🩺 are essential for diagnosis and management.

📖 About Astigmatism

Astigmatism is a common refractive error caused by an irregular corneal or lens curvature. Instead of being perfectly spherical, the cornea is uneven, preventing light from focusing on the retina. This results in blurred or distorted vision 👓. It may occur with myopia (short-sightedness 👀) or hyperopia (long-sightedness 🔭).

🔄 Irregular corneal curvature → distorted vision.
🧬 Can be congenital or acquired.

⚙️ Aetiology

👶 Congenital: Present at birth due to inherited corneal shape irregularities.
🤕 Acquired: Trauma/injury altering corneal curvature.
⚠️ Other causes: Keratoconus (progressive cone-shaped cornea) → irregular astigmatism.

👩‍⚕️ Clinical Presentation

👓 Blurry vision: All distances affected.
🔍 Distortion: Objects appear wavy, bent.
😣 Eye strain: Especially with reading/screens.
🤯 Headaches: From focusing effort.
🌙 Night vision difficulty: Glare & halos around lights.
👥 Double vision: In severe cases.

🧾 Differential Diagnosis

⚠️ Keratoconus: Progressive thinning/cone shape.
🩹 Corneal scarring: Post-infection or trauma.
🌫️ Cataracts: Lens opacities mimicking blur.
💧 Dry eye: Fluctuating vision + discomfort.
🔦 Posterior capsule opacification: After cataract surgery.

🔍 Investigations

📊 Visual acuity test: Snellen chart.
🎯 Refraction test: Phoropter/autorefractor for prescription.
🪞 Keratoscopy: Line reflections for corneal curvature.
🌐 Corneal topography: Computer map of corneal surface.
📏 Pachymetry: Corneal thickness.
🔬 Slit-lamp exam: Detects structural abnormalities.

🛠️ Management

👓 Corrective lenses:
- ✅ Spectacles (cylindrical lenses).
- 👁️ Toric contact lenses.
- 💎 Rigid Gas Permeable (RGP) lenses.
🔪 Refractive surgery:
- LASIK/PRK – reshape cornea.
- Lens replacement with IOL.
- Intrastromal corneal rings.
🧬 Corneal collagen cross-linking (CXL): Stabilises keratoconus-related astigmatism.
🌐 Topography-guided laser: Customised reshaping.
🌙 Orthokeratology: Overnight rigid lenses flatten cornea temporarily.
📅 Monitoring: Essential for progressive/irregular cases.

💡 Clinical Pearl: Astigmatism → think of “blurred AND distorted” vision, unlike pure myopia/hyperopia which is just blurred.

📚 Case Example

👩 A 19-year-old student complains of blurred vision when reading 📖 and frequent headaches 🤯. Exam: Visual acuity 6/12, improving to 6/6 with cylindrical correction. 📊 Corneal topography confirms regular astigmatism. ✅ Management: Prescription glasses with cylindrical lenses.

🌟 Prognosis

✅ Excellent with lenses/surgery.
🔁 Regular checks important, esp. for progression.
⚠️ Irregular astigmatism (e.g., keratoconus) may require advanced options.

📖 References

American Optometric Association – Astigmatism
Mayo Clinic – Astigmatism
Kanski, J. & Bowling, B. Clinical Ophthalmology, 2011.
National Eye Institute – NEI Astigmatism

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Astigmatism