Ljubljana, SLOVENIA – Toric IOLs are “forgiving” devices, as small amounts of rotation are well tolerated and do not induce significant image alteration, according to a study conducted with the aid of a device simulating the optical characteristics of the human eye.
“The literature suggests that rotation over 30° induces loss of the whole cylindrical correction. In our study, we found that the toric effect is lost at 45°. For IOL rotations within 5°, image quality does not change significantly,” Daniele Tognetto, MD, said at the winter meeting of the European Society of Cataract and Refractive Surgeons.
An experimental optoelectronic test bench including an optoelectronic mechanical device was used. A cylindrical lens of –3.75 D was placed in front of the optic bench to simulate corneal astigmatism. A toric lens was placed at different axis positions, and image quality changes were analyzed using special software.
When the axis of the lens was rotated within 5° from the proper position, image definition decreased by 7%. At 15°, the loss was about 20%, and at 25°, it was 40%. With an axis rotation of 45°, image definition decreased by more than 50% and was comparable with the image obtained with no cylindrical correction, Tognetto said.
Disclosure: Tognetto has no relevant financial disclosures.