Astigmatism is a common refractive error in which the cornea and the lens of the eye have an irregular curvature. For the cataract patient, eliminating corneal astigmatism results in better overall vision following cataract surgery and the implant of an intraocular lens (IOL).
The most commonly used procedure to correct preexisting mild to moderate astigmatism (less than -3.0 diopter) is Limbal Relaxing Incisions (LRIs). Surgeons make a pair of incisions at the corneal limbus and induce changes in the corneal astigmatism by varying the length, depth and location of the incisions.
The procedure is performed at the same time as cataract surgery and takes just a few minutes to complete. Benefits include an almost immediate recovery of vision and reduced healing time and risk associated with a secondary procedure.
Toric Lens Implants
Toric Lens Implants are intraocular lenses (IOLs) designed to correct moderate to high astigmatism. Similar to other IOLs, toric lens implants are made of a soft plastic material that can be folded and inserted into a small incision during cataract surgery.
Although classified as a monofocal lens, correcting vision at one distance only, toric IOLs differ from other IOLs in that they are designed with two powers one to correct astigmatism; the other to correct myopia or hyperopia. As with other monofocal IOLs, glasses or contacts are still required to achieve a full range of vision following surgery.
Toric lens implants may be used in combination with Limbal Relaxing Incisions (LRIs) and/or Laser Enhancement Surgery, depending on the degree and severity of the astigmatism. Toric IOLs are also indicated in patients with lenticular astigmatism, a less common form of astigmatism that occurs when there is an irregularity in the shape of the natural crystalline capsule.
Cataract Phaco with a Toric Lens
Cataract Femto with a Toric Lens
Cataract Femto with a Monofocal Lens
Laser Enhancement Surgery is the latest tool for treating high astigmatism greater than -3.0 diopter. The procedure is commonly used in combination with Limbal Relaxing Incisions (LRIs) and/or Toric Lens Implants to help patients achieve optimal vision following cataract surgery.
Laser enhancement surgery has some distinct advantages in the treatment of corneal astigmatism for the cataract patient:
- Laser enhancement surgery offers superior precision.
- Laser enhancement surgery can correct high astigmatism, which might not be fully corrected using only LRIs or toric lens implants.
- Laser enhancement surgery offers an alternative to toric lens implants for those patients who desire multifocal intraocular lenses.
The biggest disadvantage of laser enhancement surgery is that is must be completed post-operatively, generally six weeks after cataract surgery. There is also additional cost involved, however, for patients seeking the best possible vision following cataract surgery, the benefits often outweigh the costs.