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.

Long-term Outcomes of Boston Type I Keratoprosthesis, and Efficacy of Amphotericin B and Povidone-Iodine in Infection Prophylaxis

PURPOSE

To evaluate the long-term outcomes, anatomic retention, and complications of Boston type I keratoprosthesis (KPro).

DESIGN

Retrospective, interventional case series METHODS: A retrospective chart review of implantations performed January 2008-December 2017 was conducted. Risk factors for anatomical retention and functional success were analyzed. The incidences of infections with and without antimicrobial medications were compared.

RESULTS

Twenty-seven eyes of 26 patients were recruited. The most common indication for KPro surgery was failed penetrating keratoplasties (22 eyes, 81.5%). All patients had preoperative best-corrected visual acuity (BCVA) worse than 3/60. Over the mean follow-up of 83.4 ± 28.4 months, 15 eyes (55.6%) demonstrated improved BCVA. The anatomical retention rate was 88.9%, and the functional success rate was 44.4% (retained KPro with BCVA ≥ 3/60). Eyes with ocular surface disease (OSD) had significantly more complications than those without OSD. The most common complications were retroprosthetic membrane formation (15 eyes, 55.6%) and infection (13 eyes, 48.1%). Infectious keratitis was primarily caused by gram-positive bacteria, whereas endophthalmitis was chiefly caused by fungal infection. The infection incidence was significantly lower in eyes using topical 0.1% amphotericin B and 5% povidone iodine (P = .008 and .021, respectively).

CONCLUSIONS

With its good retention rate and visual outcomes, Boston type I KPro could be an alternative treatment for patients with conventional penetrating keratoplasty failure, especially with appropriate patient selection and complication prevention. Standard prophylactic antibiotics with the addition of topical 0.1% amphotericin B and 5% povidone iodine might be optional effective regimens for infection prevention, especially in tropical countries.

Vitreoretinal Complications in Boston Keratoprosthesis Type 1

PURPOSE

To evaluate the incidence of vitreoretinal complications, treatment modalities, and the visual outcomes in a large cohort of eyes that underwent Boston Keratoprosthesis (KPro) implantation.

DESIGN

Retrospective, interventional case series.

METHODS

132 eyes of 114 patients who underwent KPro implantation at the Centre Hospitalier de l'Université de Montréal from 2008 to 2017 were included with at least 1 year follow-up. Charts were reviewed and data was collected, including demographics, initial corneal indication for surgery, posterior segment complications, preoperative and postoperative visual acuity.

RESULTS

Mean follow-up was 68.2 months and 61.4% of eyes developed postoperative vitreoretinal complications (VRC). The most common VRC was RPM formation (38.6%, n=51) followed by RD (15.2%, n=20), CME (12.1%, n=16), ERM (9.8%, n=13), endophthalmitis (9.1%, n=12), sterile vitritis (7.6%, n=10), vitreous hemorrhage (6.8%, n=9), choroidal detachment (3.0%, n=4) and central retinal vein occlusion (0.7%, n=1). BCVA improved in the no VRC group from 1.74 ± 0.33 logMAR to 1.33±0.83 logMAR and in the VRC group from 1.74±0.36 logMAR to 1.52±0.83 logMAR, without any statistically significant intergroup differences (p=0.231). RD was the only significant complication associated with poorer visual outcomes (p=0.001).

CONCLUSION

Potentially blinding secondary complications occur in the majority of patients and frequent monitoring is necessary, specifically in the early and intermediate postoperative periods. This study evidenced significant improvements in visual outcomes of KPro eyes, including those that developed postoperative vitreoretinal complications.

Blood Levels of Tumor Necrosis Factor Alpha and Its Type 2 Receptor Are Elevated in Patients with Boston Type I Keratoprosthesis

Purpose: Boston keratoprosthesis (KPro) patients are prone to glaucoma even with well-controlled intraocular pressure (IOP). Recent experimental data have shown that soluble tumor necrosis factor alpha (TNF-α) after ocular injury may contribute to progressive retinal damage and subsequent glaucoma. This study evaluates the blood plasma levels of soluble TNF-α, TNF receptors 1 (TNFR1) and 2 (TNFR2), and leptin in patients with Boston type I KPro. Methods: Venous blood samples were collected from KPro patients with glaucoma (KPro G, n = 19), KPro patients without glaucoma (KPro NoG, n = 12), primary angle closure glaucoma without KPro (PACG, n = 13), and narrow angles without glaucoma or KPro (NA, n = 21). TNF-α, TNFR1, TNFR2, and leptin levels were quantified using the enzyme-linked immunosorbent assay. Erythrocyte sedimentation rate (ESR) was assessed using the Westergren test. Patients with underlying autoimmune conditions or diabetes were excluded from the study. Results: All groups had similar age, body mass index (BMI), IOP, and ESR (p ≥ 0.11). The mean time from KPro surgery to blood draw was 5.3 ± 3.7 years. Compared to NA patients (0.72 ± 0.3 pg/ml), KPro G and KPro NoG patients had higher blood plasma levels of TNF-α (1.18 ± 0.58 pg/ml, p = 0.006; 1.16 ± 0.50 pg/ml, p = 0.04, respectively). Similarly, KPro G patients had higher blood plasma levels of TNFR2 (2768 ± 1368 pg/ml) than NA patients (2020 ± 435 pg/ml, p = 0.048). In multivariate analysis, KPro status remained positively associated with TNF-α levels (β = 0.36; 95% confidence intervals [CI]: 0.14-0.58; p = 0.002) and TNFR2 levels (β = 458.3; 95% CI: 32.8-883.7; p = 0.035) after adjusting for age, gender, BMI, glaucoma status, and ESR. TNFR1 and leptin levels were not significantly different in the study groups. Conclusions: We detected elevated serum levels of TNF-α and TNFR2 in KPro patients. Longitudinal studies are needed to establish TNF-α and TNFR2 as serum biomarkers related to KPro surgery. Abbreviations: BCVA: best corrected visual acuity; BMI: body mass index; CDR: cup-to-disc ratio; EDTA: ethylenediaminetetraacetic acid; ELISA: enzyme-linked immunosorbent assay; ESR: erythrocyte sedimentation rate; HVF: Humphrey visual field; IOP: intraocular pressure; KPro G: keratoprosthesis with glaucoma; KPro NoG: keratoprosthesis without glaucoma; KPro: keratoprosthesis; MD: mean deviation; NA: narrow angle; non-KPro: without keratoprosthesis; PACG: primary angle closure glaucoma; RNFL: retinal nerve fiber layer; TNF-α: tumor necrosis factor alpha; TNFR1: tumor necrosis factor receptor 1; TNFR2: tumor necrosis factor receptor 2.

Detection of laminar resorption in osteo-odonto-keratoprostheses

PURPOSE

To compare the clinical examination and computerized tomography (CT) scanning methods for the detection of laminar resorption in eyes with osteo-odonto-keratoprosthesis (OOKP).

METHODS

Patients who developed laminar resorption after OOKP surgery and had at least one CT scan of the lamina during the follow-up were included. Case records and CT images and reports were retrospectively reviewed. Each lamina of the eye was regarded as a case. The imaging and clinical data were collected in Microsoft Excel, and statistical analysis was performed on Stata-v14. The agreements and sensitivities of both the methods were compared.

RESULTS

Forty patients out of 64 were found to have laminar resorption. A total of 48 laminae were studied, which had data on the presence or absence of resorption. The sensitivity and specificity of clinical detection of resorption were 87.5% (CI 68%-97%) and 37.5% (CI 8.5%-75.5%), respectively. Whereas, the sensitivity and specificity of CT scan were 81% (CI 61%-93%) and 50% (CI12%-88%), respectively. Both the methods have detected resorption in 21 out of 32 laminae having both the clinical and CT scan data. There is a fair agreement between the two techniques in the identification of thinned laminar sites.

CONCLUSIONS

Clinical detection of laminar resorption in OOKP eyes is equally sensitive to the CT scanning. Resorption can be detected even in its early stages by clinical palpation in experienced hands. Frequent CT scanning is not indicated to detect laminar resorption. Both methods complement each other. Thinned laminar segments should be compared and correlated with both the methods for full evaluation of resorption.

Keratoprostheses for corneal blindness: a review of contemporary devices

According to the World Health Organization, globally 4.9 million are blind due to corneal pathology. Corneal transplantation is successful and curative of the blindness for a majority of these cases. However, it is less successful in a number of diseases that produce corneal neovascularization, dry ocular surface and recurrent inflammation, or infections. A keratoprosthesis or KPro is the only alternative to restore vision when corneal graft is a doomed failure. Although a number of KPros have been proposed, only two devices, Boston type-1 KPro and osteo-odonto-KPro, have came to the fore. The former is totally synthetic and the latter is semi-biological in constitution. These two KPros have different surgical techniques and indications. Keratoprosthetic surgery is complex and should only be undertaken in specialized centers, where expertise, multidisciplinary teams, and resources are available. In this article, we briefly discuss some of the prominent historical KPros and contemporary devices.

Boston keratoprosthesis - Clinical outcomes with wider geographic use and expanding indications - A systematic review

Over 2 decades of research, several design modifications, and improvements in post-operative management have made Boston keratoprosthesis (B-KPro) a viable option for patients with corneal blindness for whom traditional keratoplasty procedure has a very low probability of success. In this systematic review, we examined the indications, visual outcomes, complications and retention rate of the literature published in the past 10 years (2005–2014). While most of the studies report smaller datasets (typically <50 eyes), some of the recent multicenter studies have reported large datasets (up to 300 eyes). Most of the literature is published from the US; however, last few years have witnessed some papers reporting the successful use of B-Kpro from developing countries or arid climatic conditions (such as the Kingdom of Saudi Arabia). Due to differences in the causes of corneal blindness in different geographic regions, newer indications for B-Kpro are emerging (e.g. trachoma). Additionally, improving clinical outcomes and increasing surgeon confidence have also expanded indications to include cases of unilateral visual impairment and paediatric age. We observed that there is growing body of evidence of successful clinical use of B-KPro; however, financial challenges, lack of trained surgeons, shortage of donor corneas must be overcome to improve accessibility of B-KPro.