Time to achieve best postoperative visual acuity following Boston keratoprosthesis surgery

Boston type I keratoprosthesis versus penetrating keratoplasty following a single failed corneal graft

BACKGROUND/OBJECTIVES

To compare long-term outcomes of the Boston type 1 keratoprosthesis (KPro) with penetrating keratoplasty (PKP) in patients with a failed first PKP.

SUBJECTS/METHODS

In this retrospective comparative case series, 48 eyes of 48 patients who underwent a second corneal replacement procedure after a first failed PKP at the Centre Hospitalier de l'Université de Montréal from 2008 to 2020 were included. Minimum follow-up duration was 5 years, and patients with keratoconus were excluded since such subjects are not candidates for KPro. Main outcome measures included best-corrected visual acuity (BCVA), postoperative complications, graft survival and subsequent interventions.

RESULTS

Mean follow-up was 6.4 years for PKP and 9.6 years for KPro (p < 0.001). Preoperative BCVA was better in PKP patients (means 1.67 vs 2.13, p = 0.041). Visual outcomes were similar between groups. KPro patients developed 0.263 complication per patient-year (ppy) compared to 0.245 ppy or PKP. The most common complications for PKP were corneal complications (0.088 ppy) and glaucoma worsening (0.041 ppy). In KPro, glaucoma worsening (0.046 ppy), vitreoretinal complications (0.042 ppy) and retroprosthetic membrane (0.042 ppy) were the most frequent. Graft failure (69.6 vs 20.0%, p < 0.001) and reoperation rates (56.5 vs 12.0%, p = 0.001) were significantly higher for PKP. Failure mainly resulted from decompensation or rejection in PKP, while all five failures in KPro were caused by melt and/or extrusion.

CONCLUSIONS

Both interventions showed similar visual outcomes. Complication profiles were different, with more posterior segment complications in the KPro group, and more corneal complications in the PKP group, often necessitating regraft.

The treatment of end-stage corneal disease: penetrating keratoplasty compared with Boston type 1 keratoprosthesis

Penetrating keratoplasty (PKP) yields excellent results for restoring vision in end-stage corneal diseases. However, its success is limited to high-risk diseases such as aniridia, chemical burns, autoimmune corneal diseases, and herpetic eye disease. Boston type 1 keratoprosthesis (BKPro) offers another option to these patients. Since 1992, improvements in perioperative management and device construction have significantly increased the use of BKPro worldwide and challenged the therapeutic role of PKP in these patients. This review aims to evaluate BKPro's place in the treatment algorithm of these high-risk patients to assist surgeons' decision-making. PKP and BKPro are compared in three outcome categories: visual acuity, graft retention and failure, and complications profile. Special attention is given to comparing secondary BKPro versus repeated PKP as well as primary BKPro versus primary PKP. We conclude that secondary BKPro bears a better prognosis than repeated PKP in most high-risk patients. Similarly, primary BKPro likely confers improved outcomes over primary PKP in most high-risk recipients. However, current evidence is based on retrospective designs, and controlled prospective randomized trials are required to validate these conclusions.

Wide-field vitreoretinal surgery in eyes with Boston type 1 keratoprosthesis

PURPOSE

Vitreoretinal surgery in eyes with Boston type 1 keratoprosthesis (KPro) is challenging due to narrow optic of the KPro. This study analyzed the results of pars plana vitrectomy (PPV) using a wide-field imaging accessory, Resight®700 Fundus Viewing System (Carl Zeiss Meditec, Inc., Germany), for better intraoperative peripheral retinal imaging.

METHODS

In this retrospective case series, KPro patients who underwent simultaneous or sequential PPV at Dokuz Eylul University Hospital between June 2010 and January 2020 were evaluated in terms of anatomic and visual prognoses, as well as KPro- and PPV-associated complications.

RESULTS

Among 9 KPro eyes that necessitated vitreoretinal surgery, 3 (33.3%) underwent simultaneous KPro and PPV due to proliferative vitreoretinopaties; 6 (66.7%) underwent PPV for retinal detachment or suprachoroidal hemorrhage that appeared after KPro surgery. Retina could be attached in 7 eyes (77.8%), and vision improved in 3 eyes (33.3%). In 1 eye, injected silicone oil moved to subconjunctival area through glaucoma drainage device.

CONCLUSION

In eyes with a Boston KPro, wide-angle viewing systems helped handling peripheral retinal problems successfully during PPV, with no observed inadequacy of imaging. Despite anatomical success in most cases, visual prognosis depends on vitality of the macula and the optic disc.