Knowledge Base
2. Linking EyeSpace to your topographer

1. EyeSpace Scleral Diagnostic Fitting Set

10. EyeSpace ScleralCharl Laas

EyeSpace Scleral Diagnostic Fiining set parameters

The EyeSpace Scleral diagnostic fitting consists out of 26 lenses divided into 'Eye conditions' to ease lens selection in the absence of known corneal sagittal height values.

Diagnostic Fitting Set Parameters

Lenses 1-17 are for keratoconus, and are separated into mild (lenses 1-6), moderate (lenses 7-12) and severe (lenses 13-17). Moving from lens 1 to 17 the lenses increase in sagittal depth and steepen in BOZR to mimic the nature of the steepening cornea in worsening keratoconus.

The keratoconus lenses are organised in groups of 3 with the same minimum SAG@15mm value and increasing by 200 microns in each following group. Within the groups, the first lens is rotationally symmetric, and the second and third lenses are toric with 150 and 250 microns of toricity respectively.

Due to the toric shape of the paralimbal sclera, the majority of scleral lenses require a toric periphery to best fit the eye. It is recommended to select the second lens in the group of 3 that has 150 microns of toricity.

Lenses 18-22 are for Corneal Grafts and have flatter BOZR to fit the shape of a corneal graft eye better, increase in sagittal depth and are all toric with 150 microns of toricity.

Lenses 23-24 are for post refractive surgery. These lenses have the flattest BOZR in the set to fit the flat post-surgical shape of these eyes. Both lenses are rotationally symmetrical and relatively shallow in sagittal depth.

Lenses 25-26 are large diameter lenses for severe ocular surface disease conditions such as Sjogren's syndrome, and Steven Johnsons syndrome.

Trial Fitting Instructions

Step 1 - Eye Condition

  • First identify which condition best describes your patient.

Step 2 - SAG@15mm

  • To select the appropriate diagnostic lens, you must determine the sagittal depth of the eye at the 15.00 mm chord (SAG@15mm). You can use either your slit lamp or corneal topographer to determine the starting sagittal value.

    • Slit Lamp: You can use the Smith technique to measure the anterior chamber depth. The SAG@15mm(Lens) = AC Depth + 200 microns.
    • Corneal Topographer: You will need to find the value for the horizontal sagittal height at the 10.00 mm chord from your topographer software. SAG@15mm(Lens) = SAG@10mm(cornea) + 2200 microns.

Note: If the calculated SAG@15mm value falls between two lens values, select the higher sagittal height diagnostic lens.

Step 3 - Lens Insertion

  • Inspect and clean the lens thoroughly.
  • Fill the lens with a preservative free saline solution.
  • Insert the lens directly over the cornea with the patient in a face down position to prevent air bubbles forming under the lens. If an air bubble is present under the lens, remove and reinsert.

Step 4 - Assess the Lens Fit and Optics

  • Assess the central and limbal post lens tear thickness (PLTT) using biomicroscopy or OCT.
  • Assess the SLZ using biomicroscopy or OCT in all four quadrants.
  • Note and record the meridional position of lens markings for toric lenses.
  • Retinoscopy of the lens on eye. Make note of central and peripheral retinoscopy reflex.
  • Perform a sphero-cylindrical refraction over the lens on eye.
  • Perform a topography over the lens on eye to assess lens flexure and surface quality.