How to Fit Empirically

UltraHealth® and Duette® lenses can now be fit empirically, without the need of a fit set. Or, an empirical consultation may be used to identify a starting trial lens from a fit set. The starting lens is then evaluated for fit and an over refraction provides information for lens power. Our Technical Consultants take your measurements over the phone and are able to place your order for you.

Provide Information for Lens Design

Provide a topography (PDF or raw data) with the following information to a SynergEyes Technical Consultant:

  1. Keratometry readings
  2. Eccentricity data, often listed as e, e2, CEI, Shape Factor, or Q value
  3. HVID
  4. For power: Previous RGP or scleral data with base curve and over-refraction.

Using the data listed above, a recommended lens will be ordered. Determining power empirically on an irregular cornea is inherently inaccurate. Provide previous rgp/scleral data with over refractions.

A first lens will be designed and ordered from the measurements. Or, a first lens from the diagnostic set will be recommended as a starting point for an in-office fitting.

In the ideal fit, clearance is 100 microns over the apex. After settling, the final lens should clear the apex of the cornea about 40-50 microns and the inner landing zone would have feather clearance.

The Dispense Visit

The same fitting principals apply as they would with a diagnostically ordered lens.

Perform a fluorescein evaluation of the lens on the eye before the tears wash out the fluorescein.

Observe the following at the dispense visit:

  • Assess the central vault: Verify vault by assessing the clearance at the apex of the cone by optic section or OCT. Desired vault is roughly half of the lens thickness, or 50 to 100 microns. If there is bearing, increase the vault. If there is excessive clearance, then decrease the vault.
  • Check centration. The lens should center overall and the skirt should lie flat without fluting or bubbles. The lenses may move very little on primary gaze blink, but should move freely with a push up test.
  • Assess the inner landing zone. The inner landing zone should show a slightly darker color of green. If you see a dark ring of heavy bearing sometimes accompanied by poor centration, then there is not enough clearance of the inner landing zone. Confirm that the lens is not overvaulted. If vault is correct, increase the skirt. If there is excessive clearance or excessive movement, confirm the lens is not overvaulted and then flatten skirt.
  • Verify the correct skirt curve. Once the correct vault is determined, if there are bubbles after insertion or the skirt is fluting, then steepen the skirt.
  • Verify the correct power by performing an over-refraction. If the power change is minimal have the patient wear the lenses for a week and check again at follow up before an exchange is made. The lens to cornea relationship may change slightly as the lenses settle over a few days’ time and it is common for the small over-refractions to disappear after that point. If acuity is not achieved as expected, check for residual lenticular astigmatism or lens flexure.

Troubleshooting Tips

Patient Tips:
  • Set proper patient expectations; reassure there will be initial lens “awareness” that will go away in a few days with gradual build-up of wear time.
  • Have patient review insertion, removal and lens care video PRIOR TO DISPENSE APPOINTMENT.
  • Dry fingers are key for removal, tissue can be used over pincher fingers for lens removal.
  • Train staff on I&R; assure patient that removal is “different” than what they are used to, but not “difficult”.
Fitting Tips:
  • Avoid making changes at lens dispense visit.
  • Remember to assess inner landing zone with each lens.
  • Discomfort at a 3-4 hour mark, a low-riding lens, and/or difficult removal may indicate over-vault.
  • If excessive movement with blink and/or bubble uptake after insertion, steepen skirt after confirming appropriate vault.
  • Impression ring may be visible after wear and is acceptable as long as there is no epithelial disruption. If there is epithelial disruption recheck the fit for over-vault or ILZ bearing.

Place Your Order

To place an empirically-fit order for Duette or UltraHealth lenses, please contact our Product Consultation Team at 1.877.733.2012, option 2, or email consultation@synergeyes.com