GP lens eye Rounds

KERATOCONUS: Profilometry-Designed Haptics and Shape Case

Sheila Morrison OD, MSc, FAAO, FSLS

History

• Chief Complaint: 54-year-old female referred for specialty contact lens prosthetic fit to alleviate photophobia secondary to fixed irregular pupil in the left eye.
• Ocular history:
  • Glaucoma, LPI’s OU
  • Keratoconus OU
  • OD: stable keratoconus for 10+ years
  • OS: PKP(15 y/o) , pupil dyscoria, iris defects, PCIOL with capsular bag fibrosis
• Systemic Health: seasonal allergies
• Medications: Xalatan, Prednisolone
• Fhx: glaucoma, keratoconus – mother and brother

Examination

• Entering visual acuities and manifest refraction:

• Slit lamp examination

• Corneal & corneoscleral topography: placido rings (Figure 1a), profilometry (Figure 1b)

Figure 1: (a. left: Placido ring topography; b. right: profilometry)

Keratometry: 37.36/50.21D
HVID 11.90mm

• • Pachymetry OS: Minimum corneal thickness 620um
  • Macula: WNL

Decision-Making Process

For best fit, comfort, ability to apply stable optics (including possible painted prosthetic iris OS) a scleral lens was selected. Profilometry is an advantage when fitting scleral lenses to determine toric, quadrant, or asymmetrical haptics. The patient was impressed with technology and most excited about data-driven designs. A painted lens would be considered after the best fit and vision achieved with a scleral lens is determined.

Fitting and Evaluation

• • Profilometry-driven design initiated using best quality scan and software to design a custom haptic scleral lens. (Figure 2) A diagnostic lens was used to determine power to apply to the lens (i.e., using an 8.87mm BC lens, power to neutralize was +2.25D).

Figure 2: Profilometry data used in software with practitioners in control of lens design and changes.

• Lens 1 dispensed in-office (Figure 3): application clearance of 352um, adequate limbal clearance, (-) impingement/blanching. VA 20/50 OS. At the 4-hour follow-up visit, settled central clearance was 255um. BCVA with over-refraction of -0.50 -1.75 x 065 was 20/30. Lens removal was slightly difficult due to lens suction. Pachymetry after four hours of wear was WNL with ~15um central thickening. The patient had several small microcysts on the host tissue and no limbal staining. Plan: dispense lenses with handling and solutions training. Order the next lens with 200Dk material, decrease sag 50um, add fenestrations for decreased lens suction, and apply toric front surface power (per over-refraction). RTC to dispense new lens with technician and follow-up in four hours to ECP.

Figure 3: Lens 1 on-eye fitting relationship

• Lens 2 provided 30/30 VA, (-)impingement/blanching, full corneal/limbal clearance, settled clearance at closest point ~200um. Still several microcysts in peripheral host tissue. Acceptable to continue lens wear.
• Requested endothelial cell count from OMD – 923mm/cm2; proceed with lens wear. Education provided to d/c lens wear immediately and RTC if any redness, irritation, halos in vision (could be a sign of edema), blurred vision. Patient was very happy with vision and no longer overly photophobic. Plan: RTC three months for EOD (8 hour) scleral lens f/u.
• Will NOT move forward with painting iris on scleral (would decrease oxygen; patient happy).
• At the three-month follow-up, fit/comfort/vision stable OS. Lens okay to finalize. Recommended to return in six months for the next follow-up visit.

Clinical Pearls

• Photophobia and visual disturbances may be reduced or eliminated with a GP contact lens alone (i.e., neutralize power and irregularity first).
• Quality of data and measurements (i.e., profilometry for example) will determine the quality of lenses produce (i.e., junk in = junk out).
• Empirical design does not replace a diagnostic lens for power determination (i.e., irregular cornea) and comfort trials (i.e., dry eye, neuropathic pain).

Beneficial Resources

1. Fadel, D. The influence of limbal and scleral shape on scleral lens design. Contact Lens and Anterior Eye 2018;41(4):321-328.
2. DeNaeyer G, Sanders D, van der Worp E, Jedlicka J, Michaud L. Qualitative Assessment of Scleral Shape Patterns Using a New Wide Field Ocular Surface Elevation Topographer. J Contact Lens Res Sci. 2017;1:12-22.
3. Consejo A, Llorens-Quintana C, Bartuzel MM, Iskander DR RJ. Rotation asymmetry of the human sclera. Acta Ophthalmol. 2019;97(2).