Toric Intraocular Lenses in Patients Post Glaucoma Filtration Surgery
The reported incidence of cataract growth following a glaucoma procedure is approximately 75% in the first year after surgery. Cataract surgery is therefore a commonly-performed procedure in the postoperative period of a glaucoma surgery. Cataracts are oftentimes removed by the glaucoma specialist, as extra precautions must be taken at the time of surgery and in the postoperative period to ensure that the previous glaucoma surgery does not fail. Because of reduced contrast sensitivity, patients with glaucoma advanced enough to require surgical intervention are usually not candidates for a multifocal intraocular lens. However, these patients can be ideal candidates for a monofocal toric intraocular lens. Similar to the use of toric IOLs in post PK patients you have read about earlier in this newsletter, toric IOLs can also provide excellent outcomes in the glaucoma patient population.
Though placed posterior to the limbus, trabeculectomy and tube shunt surgeries can induce astigmatism. This astigmatism may fluctuate for the first several months following surgery, but is usually stable by postoperative month six. This astigmatism can be especially unpalatable for patients with excellent central visual acuity but a limited central field of vision. A toric intraocular lens can reduce or even negate the 1-3 diopters of astigmatism a filtration/glaucoma drainage implant surgery can induce. This can allow for the thrilling result of spectacle independence in the distance following cataract surgery.
The toric intraocular lens forms a solid seal with the bag into which it is placed fairly quickly. It is unlikely to move despite fluctuations in the anterior chamber depth that patients post glaucoma surgery can have in the early postoperative period. Therefore, there is no added concern about the lens rotating following surgery. Toric intraocular lenses can also be used for combined procedures in which phacoemulsification is performed at the same time as the trabeculectomy/tube shunt surgery.
Dr. Khator uses toric intraocular lenses routinely in her cataract surgery practice. She is fluent in the placement of these lenses in patients who have previously had or are undergoing simultaneous glaucoma surgery. She believes that patients with glaucoma should have access to as many benefits of technology as possible.