While having one corneal disease does not preclude the same patient from having another one, often patients who are obtaining scleral lenses fit solely for therapeutic treatment of ocular surface disease have “normal corneas”.

For patients with typical scleral lens fitting philosophies, practitioners often aim for an initial clearance of 200-300 microns over the central cornea. An estimated ~100 microns of post lens tear film can be expected to be absorbed by the cornea or leaked out as the scleral lens settles over several hours.^1-2

Over vaulting of the scleral lenses can potentially induce corneal compromise through hypoxia, which can result in neovascularization and edema.

Troubleshooting:

• Reduce suction
  • • Adjust edge/landing zone
    • Incorporate channels or fenestrations
• Reduce conjunctival prolapse
  • • Modify limbal clearance

• Scleral lens diameters are often selected based on the horizontal visible diameter of the patient’s eyes.
• Depending on the etiology and severity of the patient’s ocular surface disease, larger diameter scleral lenses may be indicated to offer additional protection for the patient’s cornea.¹ While scleral lenses are not quite defined in the same manner as it was traditionally categorized, it is still important to remember what constitutes a large diameter scleral lens at 18.0 mm+.
• Some examples of patients who may benefit from significantly larger diameter scleral lenses are patients who have graft versus host disease, neurotrophic keratitis, and more.³

• Surface wettability assesses the ability of a liquid to spread across a surface.
• For patients with OSD, the tear film is often insufficient to adequately wet the surface of the scleral lenses and allow for sufficient visibility.
• When fitting therapeutic scleral lenses, it is important to evaluate and devote close attention to the appropriate material when ordering these lenses.
  • • Oxygen permeability (Dk)
    • Wetting angle
• Tyler’s Quarterly and the GP Lens Institute (www.gpli.info) are recommended resources that provide a list of the different GP lens materials.
• Select lens materials with high Dk and low wetting angles for the most optimized therapeutic lens material.
• If the patient is still experiencing difficulty with surface wettability after accounting for the Dk and the wetting angle, Tangible Hydra-PEG (Tangible Sciences) can be added to encapsulate the lens to further improve wettability, provided that the patient is cognizant of the corresponding approved solutions that can be used.
  • • It is recommended to follow the manufacturer’s and eye care practitioner’s instructions regarding contact lens disinfecting solutions for each lens material and coating.