Specialty Contact Lenses

Specialty Contact Lenses - Vaulting Champions

• Indications: 📌 SKOPE: Severe Dry Eye Disease (DED), Keratoconus/Corneal ectasia, Ocular surface protection (e.g., Stevens-Johnson Syndrome), Post-surgical (e.g., corneal graft), Extreme refractive errors.
• Types: Mini-scleral (15-18mm), large/full scleral (>18mm).
• Fitting Principles:
  • Apical (central corneal) vault: typically 200-400 µm.
  • Limbal clearance: 50-100 µm.
  • Scleral landing zone: even alignment, no impingement.
• Material Properties: High $Dk$ for optimal oxygen permeability.
• Advantages: Stable, clear vision; enhanced comfort; therapeutic tear reservoir.
• Potential Complications: Midday fogging, conjunctival prolapse/hyperemia, suction on removal, handling difficulties.

⭐ Scleral lenses are particularly beneficial for severe keratoconus and ocular surface diseases due to the creation of a pre-corneal fluid reservoir.

Specialty Contact Lenses - Myopia Night Guards

• Mechanism (Ortho-K): Overnight RGP lenses reshape cornea: central epithelial thinning, mid-peripheral thickening.
• Indications: Myopia control (children); temporary myopia (≤ -6.00D), astigmatism (≤ -1.75D).
• Lens Design: Reverse geometry, multiple zones.
• Fitting: Bull's-eye fluorescein pattern, good centration. Post-wear topography: central flattening.
• Materials: High Dk (e.g., Tisilfocon A, Roflufocon D/E) for overnight wear.
• Benefits: Spectacle-free daytime.
• Risks: ⚠️ Microbial keratitis, corneal staining, decentration.
• 📌 Mnemonic: Ortho-K C.A.R.E.S.: Children, Active lifestyle, Refractive stability, Eye health, Slows myopia.

⭐ Ortho-K: central flattening & mid-peripheral steepening creates peripheral myopic defocus, slowing axial elongation in children.

Specialty Contact Lenses - Healing & Hiding

• Therapeutic (Bandage) Lenses: Aid corneal healing.
  • Goals: Pain relief, promote re-epithelialization, mechanical protection.
  • Materials: High $Dk/t$ silicone hydrogel (extended wear approved).
• Prosthetic Lenses: Address functional/cosmetic defects.
  • Goals: Improve cosmesis, ↓ photophobia, occlude pupil.
  • Types: Translucent tinted, opaque printed/painted.

Indications Comparison:

Specialty Contact Lenses - Irregularity Tamers

• Specialty RGPs: For irregular corneas.
  • Indications: Keratoconus, Pellucid Marginal Degeneration (PMD), post-keratoplasty, post-refractive ectasia.
  • Designs: Rose K2, KCG, Dyna Intra-Limbal; PMD designs: ↑ inferior edge lift.
  • Fitting: Apical clearance/light feather touch, good peripheral alignment.
• Hybrid Lenses: RGP optics, soft lens comfort.
  • Structure: Central RGP, peripheral soft skirt.
  • Indications: RGP optics with soft comfort, irregular corneas, RGP intolerance.
  • Pros: RGP vision, soft comfort, stability.
  • Cons: ↑ Cost, complex care, skirt tightening, debris trapping.

⭐ Rose K lenses for keratoconus feature complex geometry (multiple posterior peripheral curves, aspheric optic zones) for better conformity to irregular corneas.

High‑Yield Points - ⚡ Biggest Takeaways

• Scleral lenses: For keratoconus, severe dry eye, irregular astigmatism; vault cornea, create tear reservoir.
• Orthokeratology (Ortho-K): For myopia control; overnight corneal reshaping for temporary myopia reduction.
• Hybrid lenses: RGP center (optics) + soft skirt (comfort); for keratoconus, post-surgery.
• Prosthetic lenses: Improve cosmesis in aniridia, albinism, corneal opacities.
• Bandage contact lenses (BCL): Promote corneal healing, pain relief, barrier function.
• Rose K lenses: Popular RGP design specifically for keratoconus management.