The single-piece iris-enclavated Artisan® IOL is made of hard polymethyl methacrylate (PMMA). It can be implanted through a 5.5 mm wound, which subsequently requires suturing. Suturing the wound makes controlling the astigmatism more challenging and also often delays the final outcome of the surgery. Using this anterior chamber IOL also necessitates peripheral iridotomy or iridectomy. Iris-claw IOLs can be used in phakic and pseudophakic eyes.

Tehrani and Dick presented a report of a keratoconus patient who had 7.6 diopters of corneal astigmatism after keratoplasty and CDVA of 20/32 [51]. Using a toric iris-claw Artisan® lens, the UDVA improved to 20/20 after 6 months. In a larger material of 36 eyes of 35 patients, the refractive cylinder of 7.1 ± 2.0 D decreased to 2.0 ± 1.9 D at 3 years [50]. At the last follow-up, 28 % of the eyes had a refractive cylinder less than 1 D, 58 % of the eyes had a refractive cylinder less than 2 D, and 92 % of the eyes had a refractive cylinder less than 4 D. In 50 % of eyes the achieved cylinder correction was within 1 D and in 72 % of eyes within 2 D of the intended correction. The UDVA improved significantly, while the CDVA remained the same. Three eyes (8.3 %) lost CDVA more than 2 lines, three eyes lost CDVA 1 to 2 lines, in 22 (61.1 %) the CDVA remained the same or improved 1–2 lines, and in three eyes (8.3 %) CDVA improved more than 2 lines. Endothelial cell loss at 6 months postoperatively was 13.8 ± 18.7 % compared to preoperative values, and a progressive endothelial cell loss was observed at least up to 3 years. At 3 years the endothelial cell loss was 30.4 ± 32.0 % compared to preoperative values.

The Implantable Collamer® Lens (ICL™) is made of hydrophilic porcine collagen and hydroxyethyl methacrylate copolymer including ultraviolet-absorbing chromophore in the polymer chains. This lens can be implanted into the eye through a 3.0 mm corneal incision, and its implantation is indicated in phakic eyes. The latest model of the ICL™ has a central hole allowing aqueous flow from posterior chamber through the hole into the anterior chamber, which eliminates the need of peripheral iridotomy or iridectomy. Peripheral iridotomy or iridectomy was required when using previous model of ICL™.

The efficacy and safety of toric ICL™ for correction of post-keratoplasty astigmatism have been addressed in three publications. Results of altogether 14 eyes of 14 patients in two different publications have been presented [2, 18], and in one publication, a single patient was reported [1]. In these studies, the refractive cylinder decreased by 60–90 % at 12–24 months. From all 15 eyes, in five (33 %) the CDVA improved, in nine (60 %) remained the same, and in one (7 %) decreased one line. The refractive astigmatisms were reported to be stable during the follow-up periods, and no lens rotations or lens-related adverse effects were reported. The endothelial cell loss was reported not to differ from the expected endothelial cell loss after corneal transplantation [1, 2].

Two different models of toric supplementary add-on IOLs are available on the market (Table 12.1). The Torica (HumanOptics/Dr. Schmidt) is a three-piece IOL, in which the optic is made of silicone elastomer and the haptics of polymethyl methacrylate. It can be implanted through a 3.5 mm incision. Its toricity is available up to 30.0 D.

Thomas et al. described a case series of 20 patients implanted with add-on Torica IOL. The series included 15 eyes of 14 patients who had post-keratoplasty astigmatism [53]. Refractive cylinder decreased significantly in this subgroup of keratoplasty eyes from 9.7 ± 3.8 D to 2.4 ± 1.7 D at 2–6 months postoperatively. The UDVA improved significantly, while the CDVA remained the same. Postoperative surgical IOL rotation was performed in five eyes (24 %). In two eyes, graft failures occurred leading to re-graft. In addition, two case reports of Torica add-on IOL use have been reported with successful outcome both in reducing the refractive astigmatism and improving the UDVA [28, 46].

Sulcoflex is a single-piece hydrophilic acrylic IOL that can be implanted through a 2.75 mm incision. The haptics are 10° posteriorly angulated compared to the optic to avoid pigment dispersion and iris capture of this sulcus-fixated lens. Use of Sulcoflex in correction of post-keratoplasty astigmatism in two eyes of two patients has been reported recently [46]. In both eyes, a reduction of refractive cylinder and an improvement of UDVA were achieved, while the CDVA remained constant. Excessive endothelial cell loss was not observed.

Delaying the possible cataract operation at the time of keratoplasty until sutures have been removed and refraction stabilizes offers an option to use tIOLs in the capsular bag after cataract removal to correct possible ametropias. Several reports of using tIOLs consisting of a single or a few patients are available.

Wade and coworkers reported a larger case series using toric acrylic AcrySof® IOL [57]. Results of 21 eyes of 16 patients with a mean follow-up of 14.7 months were reported. The preoperative topographic astigmatism of 4.6 ± 2.1 D was reduced to refractive astigmatism of 1.6 ± 1.3 after cataract removal and use of in-the-bag tIOL. The UDVA and CDVA improved significantly. The refractive astigmatism and the visual acuities remained constant over the follow-up period and up to 3 years for some patients. Possible rotational stability was not recorded in the study.

Using a silicon optic tIOL (MicroSil 6116 TU, HumanOptics), the astigmatism has been reported to decrease after in-the-bag implantation in two different reports from the preoperative topographic astigmatism of 9.2 ± 4.1 D to postoperative refractive astigmatism of 1.6 ± 1.5 D and from 10.2 D to 2.75 D, respectively [20, 55]. The follow-up times were 3.5 months and 1 month and the numbers of eyes were 11 and seven, respectively. In all cases both the UDVA and CDVA improved. The accuracy of the axis of the IOLs during the follow-up period were 4 ± 3° (range 0–8°) and 5° (range 0–9°), respectively. Customized tIOLs are also available by the same manufacturer, and reports of successful use of tIOLs with cylinders up to 15.0 D and 30.0 D have been reported [30, 52].

Using a tIOL made of hydrophilic acrylic optic (Rayner, UK), the post-keratoplasty refractive astigmatism has been shown to decrease in 1 month from 6.2 ± 2.7 D to 2.9 ± 2.2 D (eight eyes). The rotation of the IOL during the 1 month was 8.1 ± 9.4°, and two patients required operative realigning of the IOL [48]. In another report of three cases using the same customized tIOL, the refractive astigmatism decreased from 8.3 ± 2.1 D to 0.7 ± 0.6 D with a mean rotation of 3.3 ± 1.2° during the 12-month follow-up period [44].

Treatment planning for post-keratoplasty astigmatism is made on an individual basis, and therefore it is impossible to give definitive recommendations. The patient age, corneal graft prognosis, amount and regularity of astigmatism, endothelial cell count, lens status, and other ocular pathologies should be taken into account when planning the astigmatic and refractive error treatment. Furthermore, the status of the patients’ other eye should be taken into consideration, and if it is healthy the purpose and goal of treatment should be reflected with the expectations of the patient. In almost all cases the visual performance after corneal grafting is certainly impaired compared to a virgin eye. Anterior segment optical coherence tomography (OCT) is a useful tool for analyzing the transplant contour and profile, eccentricity, and possible bulging, which all may affect the surgical decision. Comparing different surgical methods, it is obvious that none of the methods fully correct the astigmatism (Table 12.2). The realistic goal of treatment of the post-keratoplasty astigmatism is such an amount that can be finally corrected by spectacles or contact lenses, and not a plano refraction.

If the corneal graft is clear and the endothelial cell count is low, we usually approach corneal astigmatism by corneal interventions. In the case of very high corneal astigmatism, AKs followed by wedge resection seem to be the treatment of choice. If this is unsuccessful, re-grafting can be justified. If the treatment provides a reasonable effect, this may be followed by re-AKs and later possibly by intraocular approach with tIOL.

In moderate levels of astigmatism, we have currently a multitude of different techniques. These include both corneal and intraocular approaches. Excimer laser surgery, intracorneal ring segments, manual or FS laser-assisted AKs, and FS-assisted intrastromal AKs seem all to produce relatively good results. The choice of treatment is based on corneal regularity, amount of astigmatism and other refractive errors, the surgeons’ experience, and available instrumentation. It remains unclear if wave-front- or topography-guided excimer refractive surgery provides better results than conventional surgery, but this may be the best means to treat the irregular component of astigmatism.

If the endothelial cell count is high and the post-keratoplasty astigmatism is below 5 D, we would recommend trial with FS laser-assisted intrastromal AKs. If the effect is inadequate, one may consider manual AKs or either toric ICL™ or anterior chamber lenses provided that the lens is clear and the anterior chamber is deep enough. Yet, possible damage to the endothelial cells limits the usefulness of this approach. If the nucleus is less transparent, tIOL in the capsular bag may be the treatment of choice.

If the endothelial cell count is high and the graft shows moderate (less than 5 D) astigmatism, one has again a larger choice of treatment modalities that basically include all of the above. Our own approach in these cases is to first provide optimal reduction in corneal astigmatism followed by lens-based approach.