Lens Design Selection for High Astigmatism

When should I use a bitoric lens design?

“Anytime it would improve fit and/or vision. This may be as little as 1.5 to 2 diopters of corneal cylinder, depending on whether it is central or limbus-to-limbus astigmatism. Corneal topography maps can be especially beneficial in these cases. First, it can be determined if the astigmatism is at all irregular, which may contraindicate a bitoric design. Secondly, topography can show if the astigmatism is central or limbus-to-limbus. In the latter case, toric peripheral curves are also typically indicated.” (George Mera, Tru-Form Optics)

“We consider a bitoric lens design at 2.5 to 3.0 diopters of corneal astigmatism. We also commonly manufacture aspheric back surface designs, which can often result in a successful fitting relationship in the 2.0 to 3.0 diopter toricity patients before a toric design is used.” (Mike Johnson, Art Optical)

“Even with corneal cylinder as low as 1.75D, a bitoric lens might prove more beneficial to your astigmatic patients. It will likely center better and provide an even amount of tear distribution under the lens, leading to optimal comfort and corneal health. It’s good to look for that hourglass pattern in the axial map and determine the SAG toricity in the elevation map. Also, make sure to see if the corneal cylinder and axis are similar to the refractive cylinder and axis. This will give you insight into the outcome and performance of a prospective bitoric lens wearer.” (Robert Powell, Advanced Vision Technologies)

Back to Laboratory Consultant FAQ >