Orthokeratology

Orthokeratology - Shaping Sight Overnight

• Definition: Non-surgical, reversible corneal reshaping using custom rigid gas permeable (RGP) contact lenses worn overnight.
• Goal: Temporary correction of myopia (typically up to -6.00 D) and astigmatism (up to -1.75 D).
• Mechanism:
  • Reverse-geometry lenses apply gentle hydraulic pressure.
  • Central cornea flattens; mid-peripheral cornea steepens.

  ⭐ Mechanism involves central corneal epithelial thinning and mid-peripheral stromal/epithelial thickening due to hydraulic forces under the lens.

• Indications:
  • Myopia control in children (slows progression).
  • Adults desiring spectacle/daytime contact lens freedom.
• Key Points:
  • Effect lasts 1-2 days; requires nightly wear.
  • ⚠️ Risk: Microbial keratitis (requires strict hygiene).

Orthokeratology - Ideal Eyes & No-Goes

⭐ Typically effective for myopia up to -6.00 D and with-the-rule astigmatism up to -1.75 D.

Orthokeratology - The Reshaping Masters

• Goal: Temporary corneal reshaping (myopia, astigmatism) using specially designed rigid gas permeable (RGP) lenses.
• Mechanism: Overnight wear of reverse geometry lenses flattens central cornea, steepens mid-periphery.
  • Corrects myopia typically up to -6.00 D, astigmatism up to -1.75 D.
• Lens Design: Reverse geometry with specific zones.
  • Zones: Central (treatment/optic zone), Reverse curve, Alignment curve(s), Peripheral curve.
• Fitting Assessment:
  • Corneal topography: Essential for baseline and monitoring changes.
  • Fluorescein pattern:

    ⭐ A "bull's-eye" fluorescein pattern (central touch/bearing, mid-peripheral clearance, peripheral alignment) is crucial for successful fitting.

• Key Benefits: Spectacle-free daytime vision, potential for myopia control in children.
• Primary Risks: Microbial keratitis (requires strict hygiene), corneal staining, epithelial defects. Effect is reversible upon discontinuation.

Orthokeratology - Perks, Pitfalls & Pointers

• Perks (Outcomes & Benefits):

  • Temporary myopia reduction (e.g., up to -6.00 D) & astigmatism (e.g., up to -1.75 D).
  • Spectacle/contact lens-free daytime vision.
  • Potential for myopia progression control in children.
  • Reversible upon discontinuation.

• Pitfalls (Risks):

  • ⭐ Increased risk of microbial keratitis, especially with Pseudomonas aeruginosa, is a significant concern requiring strict hygiene and compliance.

  • Corneal epitheliopathy (staining, erosions).
  • Lens decentration or adherence.
  • Visual disturbances: glare, haloes, monocular diplopia (often transient).
  • Higher cost & demanding compliance.

• Pointers (Ongoing Management):

  • Emphasize strict lens hygiene (hand washing, no tap water) & care regimens (e.g., peroxide-based systems).
  • Regular follow-up is crucial for monitoring corneal health and refractive effect: 1 day, 1 week, 1 month, 3 months, then 6-monthly.
  • Promptly manage complications: lens adjustments for decentration; lubricants or temporary discontinuation for mild staining.

High‑Yield Points - ⚡ Biggest Takeaways

• Ortho-K involves overnight wear of reverse-geometry RGP lenses.
• It achieves temporary myopia correction by central corneal flattening.
• A key application is myopia control in children, slowing progression.
• Corneal changes are completely reversible after stopping lens use.
• Microbial keratitis is the most serious complication; strict hygiene is vital.
• Corneal topography is essential for fitting and follow-up.
• Best for low-to-moderate myopia (up to -6D) and some astigmatism.