Glaucoma after penetrating keratoplasty and keratoprosthesis

PURPOSE

To compare visual and glaucoma outcomes in patients with known glaucoma after a penetrating keratoplasty (PKP) or a Boston Keratoprosthesis Type 1 (KPro) as a second corneal replacement procedure.

DESIGN

Retrospective interventional case series.

PARTICIPANTS

Charts of 141 eyes that underwent either a PKP or KPro at the Centre hospitalier de l'Université de Montréal after one failed PKP from 2008 to 2020 were reviewed. Forty-six eyes with preoperative glaucoma were included.

METHODS

Data collected included demographics, indication for the initial surgery, best corrected visual acuity (BCVA), concurrent ocular disorders, number of glaucoma medications, need for glaucoma surgery, cup-to-disc ratios (CDRs), mean RNFL thickness, and visual field (VF) characteristics. Primary outcomes were glaucoma progression trends. Secondary outcomes were visual outcomes and need for additional procedures.

RESULTS

Mean follow-up was 4.7 years for the PKP and 7.3 for the KPro group (P<0.007). 30.6% of PKP compared to 70.5% of KPro patients were diagnosed with glaucoma preoperatively. Glaucoma worsened similarly in both groups; this is based on an analysis of the number of glaucoma medications, CDR, need for glaucoma surgery, and characteristic VF changes. Patients in the PKP group required significantly more regrafts than patients in the KPro group (31.8 vs. 8.3%; P=0.045).

CONCLUSIONS

A preoperative diagnosis of glaucoma does not preclude KPro implantation. In glaucomatous eyes, the disease progressed similarly in both groups. Since both procedures increase the risk of worsening glaucoma, close follow-up is recommended. KPro may decrease the need for further corneal transplantation surgery.

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.

Post-operative outcomes associated with Boston type 1 keratoprosthesis implantation in Northeast China

The aim of the present study was to investigate the post-operative outcomes associated with Boston type 1 keratoprosthesis (Kpro-1) implantation in the treatment of patients with corneal blindness in Northeast China. Clinical data of patients who had undergone Kpro-1 implantation between July 2010 and November 2014 were retrospectively collected. The visual performance, implant retention and post-surgical complications were recorded for each patient. A total of 20 patients (20 eyes) with corneal blindness were included in the study. Prior to surgery, the patients exhibited poor vision and decreased levels of light perception. At 3 days, 1 month, 6 months, 1 year and 2 years post-surgery, logarithm of the minimum angle of resolution values were significantly decreased compared with the pre-operative values. The initial Kpro-1 implants were retained in 16 eyes. Regarding the post-operative complications, six patients exhibited retroprosthetic membrane formation, two patients presented with endophthalmitis, two patients developed secondary glaucoma, two patients experienced optical cylinder detachment, two patients presented with corneal melting, three patients had retinal detachment, three patients developed corneal ulcers and one patient had secondary optic neuropathy. Overall, the results of the present study suggested that implantation with Kpro-1 may represent an alternative therapeutic strategy for patients following previously failed keratoplasty in Northeast China. Serious complications associated with Kpro-1 implantation are common, and thus, suitable patient selection, continuous follow-up and early treatment interventions are recommended.

Corneal graft dellen in a patient implanted with a Boston keratoprosthesis type 1

The purpose of this study was to report a case of corneal dellen in a patient implanted with a Boston type 1 keratoprosthesis (KPro), which rapidly appeared after the loss of the large-diameter soft contact lens. This study is an observational case report of a 56-year-old man who underwent KPro implantation in his right eye in November 2010. In March 2014 during a follow-up visit, two areas of corneal dellen were observed. The patient had lost his bandage contact lens. With the application of a new soft contact lens, the thinned areas recovered completely within 5 days. After keratoprosthesis implantation, it is necessary to maintain uninterrupted wear of a bandage contact lens as it allows for adequate ocular surface hydration and prevents consequent complications. This case report highlights the need to provide proper instructions to such patients, in order to minimize the risk.