Scleral Lenses Over Toric IOLs for sharper vision,

by Dr. Charles McBride, McBride Optometrists, Beaverton, OR

Toric IOLs come in handy in cases when the patient has a high degrees of corneal astigmatism. With standard IOLs, the effects of any corneal astigmatism remain. With toric IOLs, the IOL cylinder is oriented in the opposite direction as the corneal cylinder and their effects cancel, resulting in improved unaided vision.

What about fitting a patient that has toric IOLs with scleral lenses? The process is the same as fitting any other scleral lens.

Step 1. Obtain a proper lens fit.

Step 2.  Perform a spherocylindrical over-refraction.

Step 3. Incorporate the over-refraction into the lens power taking lens orientation into account.

CASE AT A GLANCE

• Patient: Shelley, an avid tennis player, had LASIK bilaterally in 2000 and bilateral cataract surgeries with toric IOLs in 2015.

• Complaint: Wants sharper vision for tennis, without glasses.

• Manifest Refraction:

•   OD +0.25-0.75×093 (20/20)
•   OS +0.25-1.25×075 (20/20)

Corneal tangential curvature

The scleral shapes were measured using the Pentacam AXL Wave and the data was exported into Gaudi lens design app to design the lenses following the profile of  corneal and sclera point clouds. Lens power was estimated using spherical scleral trial lenses yielding a spherocylindrical over-refraction which was incorporated into the design.

Gaudi digitization of corneal and scleral shape

Gaudi Scleral Design Software

At the initial dispense, the fit was excellent, but the vision was off with an over-refractions of:

OD +2.00-1.50×087

OS +2.00-1.50×092

The new lens powers were determined using a cross-cyl calculator taking rotation into account, which was seven degrees and three degrees counter-clockwise in the right and left lenses respectively.

Final lens powers:                                              Over-refractions:

OD +2.25-2.75×080                                             OD Pl sph 20/15 (-2)

OS +2.25-2.75×088                                              OS Pl sph  20/15 (-2)

Topography over the scleral lenses shows the front toricity needed to account for the toric IOLs

Anterior segment OCT of the central vault of the right and left lenses

Looking at the patient’s very mild refractive error, scleral lenses might seem to be overkill, but given her desire for improved vision while playing tennis without eyeglasses, what are the options? The most popular choice would have been soft toric lenses, but a patient troubled by such minor refractive error may also be troubled by the rotational instability inherent in soft torics. A corneal GP lens would need to be a front toric, so the same rotational issues would apply, not to mention the small optic zone size, comfort and movement upon blinking. Hybrid lenses aren’t available with front toricity so those are out. A heroic LASIK enhancement might help, but I wouldn’t bet on it. Aside from the cost, scleral lenses were the best solution, with no movement upon blinking, perfect rotational stability for the toric optics, and a large optic zone reducing the aberrations induced by the small LASIK optic zone. For this patient, the cost wasn’t an issue and she is thrilled with the results.

Dr. McBride has received no remuneration from EYEXY, including for the writing of this blog.