Knowledge Base
2. Linking EyeSpace to your topographer

3. Incorrect Sagittal Toricity

11. Scleral TroubleshootingCharl Laas

It is important to equalise the downforce pressure of the SLZ onto the sclera in all meridians to have a healthy and comfortable scleral fit. The EyeSpace Scleral SAG@15 values of the flat and steep meridians must be individually adjusted until both an average PLTT of 150 microns and a 360-degree seal with the SLZ is achieved.

Too little sagittal toricity

In a fit with too little sagittal toricity, all the weight of the lens bears down on the flat meridian of the lens, which in the example below is located on the 0 - 180 degree axis.

Slit lamp examination will show meridional blanching, with wide blanching visible in the flat meridian and little to no blanching in the steep meridian. Over topography of the lens on eye will present with lens flexure in the steep meridian of the lens. The -NaFL test should also confirm tears flowing in under the steep meridian SLZ.

To correct the fit, only the SAG@15 value of the steep meridian must be increased until the steep meridian SLZ seals off on the scleral.

Too much sagittal toricity**

In a fit with the too much sagittal toricity, all the weight of the lens has shifted over to the steep meridian of the lens, which in the example below is located on the 90 - 270 degree axis.

Slit lamp examination will show an unexpected increase in the average PLTT as well as meridional blanching. Wide blanching will be visible in the steep meridian and little to no blanching in the flat meridian. Over topography of the lens on eye will show lens flexure in the flat meridian of the lens. The -NaFL test should confirm tears flowing in under the flat meridian SLZ, where the two engraving lines are located.

To correct the fit, only the SAG@15 value of the steep meridian must be decreased until the flat meridian SLZ seals off on the sclera.