Management of post-keratoplasty ametropia

Even after a successful corneal transplant, patients experience severe refractive errors, impeding their rehabilitation and satisfaction. Refractive errors can be caused by recipient pathology and corneal thickness, as well as intraoperative factors such as donor-host discrepancy, recipient's eccentric trephination, vitreous length, wound apposition, technique of suturing, and suture material. Also, wound healing and the interim between keratoplasty and suture removal contribute to astigmatism. Lamellar keratoplasty outperforms penetrating keratoplasty in terms of endothelial cell loss and endothelial graft rejection, yet the risk of developing refractive errors is comparable. Nonsurgical interventions such as spectacles and lenses fail to provide desirable vision in cases with high astigmatism and corneal irregularity. When these limitations are encountered, surgical interventions including incisional keratotomy, wedge resection, laser refractive surgeries, intracorneal segments, and intraocular lens implantation are employed. However, occasionally, none of these approaches deliver the desired effects, leading to the need for a repeat keratoplasty.

Refractive surgery after deep anterior lamellar keratoplasty: a review of the literature

PURPOSE

The main objective of this work is to present an updated review of the different surgical procedures for the correction of residual refractive errors following deep anterior lamellar keratoplasty (DALK) surgery.

METHODS

A review of the literature was conducted using PubMed, Web of Science, and Scopus databases. The search was conducted in January 2022 and was limited to articles published in peer-reviewed journals. The information extracted from each publication included sample size, mean follow-up time, pre- and post-operative uncorrected (UDVA) and corrected distance visual acuity (CDVA), pre- and post-operative refraction and spherical equivalent (SE), safety and efficacy indexes and complications.

RESULTS

Residual ametropias, mainly high astigmatism and myopia, and the resulting anisometropia are likely to occur following DALK. They become a limiting factor and may lead to unsatisfactory visual restoration, therefore affecting patients' quality of vision and life. Alternative surgical interventions may be required to treat this residual ametropia, such as corneal refractive surgery or intraocular lens implantation. A total of 47 relevant articles were studied in detail. Different refractive surgery techniques have been shown to be effective and safe for the correction of ametropia following the DALK procedure and to improve the patient's quality of vision, although more research is needed to confirm long-term results.

CONCLUSION

The final refractive technique will depend on different factors, such as the amount of ametropia, the condition of the cornea or the patient's individual needs, economics, and occupational demands.

Phakic Intraocular Lens Implantation After Deep Anterior Lamellar Keratoplasty: Retrospective Case Series Analysis With Long-Term Follow-Up

Purpose

To report outcomes of phakic intraocular lens (IOL) implantation after deep anterior lamellar keratoplasty (DALK) to correct high ametropia.

Setting

Centro Hospitalar Universitário do Porto, Portugal.

Methods

Retrospective case series with 11 eyes submitted to phakic IOL implantation after DALK. Main outcomes measured were uncorrected and corrected distance visual acuity (UDVA and CDVA), refractive error components, tomographic parameters and endothelial cell density (ECD). The minimum follow-up was 3 years for all cases.

Results

Mean ECD loss was 8.7±6.7% at 1 year, 13.1±8.6% at 3 years (n=11; p=0.016, p=0.007, respectively) and 14.0±20.4% at 5 years (n=5, p=0.212). Mean logMAR UDVA increased from 1.27±0.90logMAR preoperatively to 0.16±0.15logMAR postoperatively (p≤0.001) and no statistically significant differences were registered during follow-up. All patients gained at least 5 lines of UDVA. 54.5% of the eyes gained 1 line in CDVA postoperative and only one eye lost one CDVA line through follow-up. Efficacy and safety indexes at 1 and 3 years were 1.01–0.97 and 1.24–1.21, respectively. Mean spherical equivalent was reduced from −7.84±4.63 D preoperatively to −1.05±1.07 D postoperatively (p=0.001). Mean percentage of reduction in refractive cylinder and spherical error was 83.8±15.8% and 73.1±31.5%, respectively, p≤0.001 for both. In one eye there was a significantly gradual ECD loss over 5 years follow-up and the patient will be submitted to IOL explant.

Conclusion

Phakic IOLs were effective for correction high ametropia after DALK, showing high efficacy and safety indexes with stability over time. However, it was registered a continuing endothelial cell loss postoperatively, which assumed to be higher than those reported in eyes without DALK.

Artisan iris-fixated toric phakic intraocular lens for the correction of high astigmatism after deep anterior lamellar keratoplasty

We report the refractive correction of high astigmatism in one eye of a 23-year-old woman following deep anterior lamellar keratoplasty (DALK) using an Artisan iris-fixated, toric, phakic intraocular lens (IOL). One year after implantation, uncorrected and corrected distance visual acuities were both 20/25, refraction was -1.00 D cylinder, and the endothelial cell count was 1827 cells/mm(2). Iris-fixated phakic IOLs are not recommended for every postkeratoplasty patient with high refractive error; however, this procedure can offer good outcomes in carefully selected cases of previous DALK.

Correction of postkeratoplasty ametropia in keratoconus patients using a toric implantable Collamer lens

PURPOSE

To evaluate the efficacy and safety of a toric implantable Collamer lens (Visian TICL®) for correction of high postkeratoplasty ametropia in patients with keratoconus. 


METHODS

Seven eyes of 7 keratoconus patients postkeratoplasty (5 M, 2 F; mean age 34.1±5.9 years, range 28-44) unable to wear glasses or contact lenses were included in the study. A foldable phakic posterior chamber Collamer toric lens was injected through a standard 3.0-mm clear corneal temporal incision. Uncorrected distance visual acuity (UCDVA, logMAR), best-corrected distance visual acuity (BCDVA, logMAR), spherical refraction, cylindrical refraction, and refractive spherical equivalent (RSE) were measured preoperatively and postoperatively. Postoperative adverse events were recorded. 


RESULTS

. The mean follow-up was 12.8±8.8 months (range 4-30). A significant (p<0.01) improvement was observed postoperatively in mean UCDVA (1.18±0.4 vs 0.2±0.1), spherical refraction (-5.89±3.43 vs 0.53±0.75), cylindrical refraction (-4.39±0.75 vs -1.74±0.84), and RSE (-8.09±3.77 vs -0.33±0.54). The BCDVA changes were not significant (0.09±0.11 vs 0.05±0.08). All patients gained ≥5 lines of UCDVA (average 7.6±1.9 lines). The number of patients with UCDVA ≥6/12 (0.3 logMAR) increased after surgery (0% vs 87.5%; p<0.01), while the number of patients with BCDVA ≥6/12 was unchanged (100% vs 100%; NS), with 0% (0/7) of patients losing ≥2 BCDVA lines. No complications were observed postoperatively. 


CONCLUSIONS

Toric implantable Collamer lens was safe and effective in correcting postkeratoplasty myopia and astigmatism in keratoconus patients.