Scleral Lenses

Scleral lenses have revolutionized the management of corneal irregularities and ocular surface diseases. Unlike corneal gas permeable (GP) lenses that rest on the cornea, scleral lenses vault the cornea entirely and land on the sclera, creating a tear-filled reservoir. This unique design offers both optical rehabilitation and therapeutic benefits, particularly for patients with keratoconus, ocular surface disease, post-surgical ectasias, and severe dry eye conditions such as Stevens-Johnson syndrome.

Scleral lenses are categorized by diameter and design intent:

• Corneo-scleral (12.5–15 mm)
   
• Mini-scleral (15–18 mm)
   
• Full scleral (>18 mm)
   
• Impression-based scleral lenses (customized to ocular shape)
   

Design selection depends on pathology, anatomical considerations, and patient tolerance.

• Keratoconus
   
• Pellucid marginal degeneration
   
• Post-RK, post-LASIK ectasia
   
• Penetrating keratoplasty (PKP) with astigmatism
   

• Stevens-Johnson Syndrome (SJS)
   
• Ocular cicatricial pemphigoid
   
• Sjögren’s syndrome
   
• Neurotrophic keratopathy
   

• Patients with coma, trefoil, and spherical aberration post-surgery or due to ectasia
   

• Pediatric aphakia, post-trauma monocular aphakia
   
• Optical alignment in severe anisometropia
   

Scleral lenses must align properly with the conjunctival and scleral shape to minimize blanching and impingement. Landing zones are often toric due to scleral asymmetry.

The lens must provide adequate clearance over the entire cornea:

• Initial central clearance: 250–300 µm
   
• Post-settling clearance: ~150–200 µm
   

The fluid reservoir offers:

• Continuous hydration for ocular surface
   
• Masking of corneal irregularities
   
• Reduced mechanical trauma
   

These lenses (e.g., Chandra HOA Sclerals) are fabricated based on a physical impression of the ocular surface, allowing for sub-micron level customization.

• Perfect alignment with the scleral anatomy
   
• Enhanced comfort and reduced fogging
   
• Ideal for patients with irregular scleral anatomy (e.g., post-surgery, trauma)
   

• Scleral lens non-responders
   
• Complex ocular anatomy
   
• Severe ocular surface disease
   
• Advanced keratoconus with limbal involvement
   

Standard lenses may not address visual distortions caused by corneal and internal HOAs. Scleral lenses can be wavefront-optimized to correct these distortions, improving contrast sensitivity and night vision.

• Aberrometry used to map Zernike components
   
• Lenses designed to align both optically and rotationally
   
• Stabilization features (e.g., prism ballast) ensure consistency
   

Scleral lenses serve as liquid bandages by:

• Reducing epithelial trauma
   
• Supporting epithelial healing
   
• Protecting against desiccation
   

• SJS & OCP: Minimizing lid trauma and maintaining a moist environment
   
• GVHD: Managing keratoconjunctivitis sicca
   
• Exposure Keratopathy: Protecting the cornea from incomplete lid closure
   

• Corneal tomography (e.g., Pentacam)
   
• OCT-based measurement of clearance
   
• Ocular surface assessment
   

• Empirical or diagnostic fit
   
• Fluorescein pattern to assess vault and landing
   

• Back surface toricity
   
• Front surface toric optics or multifocal optics
   
• Notching or microvaulting over nodules or blebs
   

• Post-settling clearance assessment
   
• Evaluation for midday fogging
   
• Lens care and wear schedule education
   

• May result from excessive tear debris
   
• Solutions: Adjust landing zone, improve edge alignment, peroxide cleaning
   

• Modern materials with Dk > 100 reduce risk
   
• Minimize central vault and reduce lens thickness
   

• Ensure proper edge lift and avoid excessive suction
   

• Instruments like sMap3D and EyeSurface Profiler allow for 360° shape analysis and direct-to-lens CAD design
   

• Allows rapid prototyping and complex surface modulation
   

• Standard RGP failed due to decentration
   
• Impression lens resolved vision and comfort, correcting >5 µm RMS HOA
   

• Bilateral scleral lenses improved comfort, vision, and halted progressive conjunctivalization
   

• HOA-optimized lens provided 20/25 vision and eliminated ghosting
   

Scleral lenses represent the pinnacle of customized ocular prosthetics, providing unparalleled visual and therapeutic outcomes. The practitioner’s expertise in interpreting corneal and scleral anatomy, integrating wavefront optics, and managing surface disease is essential. As the field evolves with digital design and impression-based fitting, the role of the optometrist becomes ever more specialized, providing transformative care for patients with the most complex ocular needs.