Background: The implantation of a phakic 6-mm-iris-claw intraocular lens requires a 6.1-6.2 mm incision. This induces a variable amount of corneal astigmatism depending on the location and the type of the incision used. The aim of the current study is to investigate the surgically induced astigmatism (SIA) of different incision types and locations. This should help to achieve nearly spherical postoperative refraction.
Patients and method: 28 eyes of 16 patients with a 1-year follow-up after an implantation of a 6-mm-non-foldable iris-claw phakic IOL were studied. 5 different incision techniques were used. These were a superior corneal incision alone (8 eyes) or in combination with a 60 degrees limbal relaxing incision (LRI) at the same axis (8 eyes), a superior sclerocorneal tunnel incision (6 eyes) and the two-incisional approach either with a sclerocorneal (4 eyes) or a pure corneal (2 eyes) main temporal incision. The SIA was calculated for each incision used.
Results: The superior corneal incision had a mean SIA of 1.2 D cyl. This SIA was enhanced by an opposite LRI by another 1 D cyl. The sclerocorneal tunnel induced 0.75 D cyl, while the two-incisional techniques delivered nearly astigmatismus neutral results.
Conclusion: A proper selection of an appropriate incision site and type allows to correct the preexisting astigmatism or to keep a spherical refraction after an implantation of a 6-mm-rigid phakic iris-claw IOL.