Fitting Tools

Helpful reference information

Here are some conversion charts and fitting tools

Diopter-to-Radius Conversion Chart

Healthy Scleral Lens Habits

Scleral Lens Fit Scales

Vertex Conversion Chart

Troubleshooting Tips

While not common, corneal edema may occur in some patients.

A lens with too much vaults can cause this. Make sure to re-evaluate your SAG value. It should be the minimum SAG that vaults with very little or preferably no apical bearing (100-150 microns after settling).

Another cause may be that the periphery of the lens is impinging into the conjunctiva. If this occurs flattening the PC’s while maintaining the appropriate SAG is indicated. Lens awareness can occur if there is too much edge lift. Excessive edge lift is caused by either the PC’s being too flat or the lens SAG being too low. If excessive edge lift is observed you should first determine if the SAG is appropriate. Often when the SAG is increased, the edge will improve.

If the lens SAG is correct then a steeper periphery is indicated. The two most common causes for SPK are either from preservatives in the solution or excessive bearing on the apex.
Because these lenses have very little or no movement, tear exchange is very slow to occur. Therefore, it is very important that a benign saline be used when inserting. This will eliminate any possibility of chemical irritation. On rare occasions metabolic debris accumulation can be an issue. Usually the patient will complain of decrease acuity after eight to ten hours wear. If this occurs have the patient remove, clean and re-insert during mid-day. Excessive redness can be a sign that the lens is fitting too tightly. Patients may complain that their wearing time is limited to only a few hours a day. Recheck the SAG value to make sure it is at minimum apical vault and adjust as necessary. If the SAG is appropriate then re-design with a flatter periphery.

Fitting Pearls

*Your goal is to find the minimum SAG Value that vaults the cornea with no apical bearing (150 microns after settling /250 microns at insertion).

1. scan

2. send

3. design

4. dispense

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