Moscow Eye Microsurgery Complex in Russia Keratoprosthesis in Beijing

Vision-Related Quality of Life After Fyodorov-Zuev Keratoprosthesis in China

PURPOSE

The purpose of this study was to assess vision-related quality of life (VR-QoL) and its determinants in patients with implanted Fyodorov-Zuev (MICOF) KPro.

METHODS

Eighty-eight patients with bilateral corneal blindness who underwent unilateral Fyodorov-Zuev (MICOF) KPro implantation were included in this cross-sectional study. VR-QoL was assessed using the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25). Univariate analyses and multivariate linear regression were used to identify VR-QoL determinants.

RESULTS

Eighty-eight patients, aged 50.00 ± 13.72 years, with a mean postoperative time of 5.13 ± 3.31 years, were included. The composite NEI-VFQ-25 score improved from 17.04 ± 5.60 to 46.00 ± 19.21 (P < 0.01) after Fyodorov-Zuev (MICOF) KPro implantation. The multivariate linear regression analysis results showed that the postoperative composite score was correlated with postoperative visual acuity (VA) of the operative eye (B = -21.66, P < 0.01). Improvement in NEI-VFQ scores was associated with better postoperative VA of the operative eye (B = -18.67, P < 0.01) and poorer preoperative VA of the fellow eye (B = 7.11, P < 0.05).

CONCLUSION

VR-QoL in patients with bilateral corneal blindness was significantly impaired but improved after Fyodorov-Zuev (MICOF) KPro implantation. Improvement in VR-QoL was inversely associated with postoperative VA of the operative eye but positively correlated with preoperative VA of the fellow eye. This study affirmed that Fyodorov-Zuev (MICOF) KPro was an effective alternative for patients with corneal blindness with respect to VR-QoL.

Keratoprosthesis in dry eye disease

Bilateral corneal blindness with severe dry eye disease (DED), total limbal stem cell deficiency with underlying corneal stromal scarring and vascularization, combined with adnexal complications secondary to chronic cicatrizing conjunctivitis is a highly complex situation to treat. In such eyes, procedures such as penetrating keratoplasty alone or combined with limbal stem cell transplantation are doomed to fail. In these eyes, keratoprosthesis (Kpro) or an artificial cornea is the most viable option, eliminating corneal blindness even in eyes with autoimmune disorders such as Stevens-Johnson syndrome, ocular mucous membrane pemphigoid, Sjogren's syndrome, and nonautoimmune disorders such as chemical/thermal ocular burns, all of which are complex pathologies. Performing a Kpro in these eyes also eliminates the need for systemic immunosuppression and may provide relatively early visual recovery. In such eyes, the donor cornea around the central cylinder of the Kpro needs to be covered with a second layer of protection to avoid desiccation and progressive stromal melt of the underlying cornea, which is a common complication in eyes with severe DED. In this review, we will focus on Kpro designs that have been developed to survive in eyes with the hostile environment of severe DED. Their outcomes in such eyes will be discussed.

A Review of the Diagnosis and Treatment of Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) can cause significant corneal vascularization and scarring and often results in serious visual morbidity. An early and accurate diagnosis can help prevent the same with a timely and appropriate intervention. This review aims to provide an understanding of the different diagnostic tools and presents an algorithmic approach to the management based on a comprehensive clinical examination. Although the diagnosis of LSCD usually relies on the clinical findings, they can be subjective and non-specific. In such cases, using an investigative modality offers an objective method of confirming the diagnosis. Several diagnostic tools have been described in literature, each having its own advantages and limitations. Impression cytology and in vivo confocal microscopy (IVCM) aid in the diagnosis of LSCD by detecting the presence of goblet cells. With immunohistochemistry, impression cytology can help in confirming the corneal or conjunctival source of epithelium. Both IVCM and anterior segment optical coherence tomography can help supplement the diagnosis of LSCD by characterizing the corneal and limbal epithelial changes. Once the diagnosis is established, one of various surgical techniques can be adopted for the treatment of LSCD. These surgeries aim to provide a new source of corneal epithelial stem cells and help in restoring the stability of the ocular surface. The choice of procedure depends on several factors including the involvement of the ocular adnexa, presence of systemic co-morbidities, status of the fellow eye and the comfort level of the surgeon. In LSCD with wet ocular surfaces, autologous and allogeneic limbal stem cell transplantation is preferred in unilateral and bilateral cases, respectively. Another approach in bilateral LSCD with wet ocular surfaces is the use of an autologous stem cell source of a different epithelial lineage, like oral or nasal mucosa. In eyes with bilateral LSCD with significant adnexal issues, a keratoprosthesis is the only viable option. This review provides an overview on the diagnosis and treatment of LSCD, which will help the clinician choose the best option amongst all the therapeutic modalities currently available and gives a clinical perspective on customizing the treatment for each individual case.

Artificial Cornea: Past, Current, and Future Directions

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Long-term outcomes of the MICOF keratoprosthesis surgery

PURPOSE

To evaluate long-term anatomical and functional outcomes of the MICOF keratoprosthesis to treat end-stage corneal blindness.

DESIGN

Retrospective review of consecutive clinical case series.

PARTICIPANTS

Between October 2000 and October 2015, at the Department of Ophthalmology of Chinese PLA General Hospital (PLAGH), a total of 132 eyes of 131 patients had undergone a MICOF keratoprosthesis implantation. Of those, 91 eyes of 90 patients were included in this study.

METHODS

Preoperative information, surgical procedures, and postoperative data were collected for each included eye.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (BCVA), keratoprosthesis retention, and significant postoperative complications were reported.

RESULTS

The most common indications for surgery were chemical or thermal burns (68.1%, 62 of 91 eyes) and explosive injury (12.1%, 11 of 91 eyes), followed by Stevens-Johnson Syndrome (10.0%, 9 of 91 eyes), Sjögren's syndrome (4.4%, 4 of 91 eyes), mucous membrane pemphigoid (3.3%, 3 of 91 eyes) and multi-penetrating keratoplasty failure (2.2%, 2 of 91 eyes). The mean follow-up duration was 8.38 ± 3.22 years (range: 5-17.25 years, median: 7.67 years). All patbients had a preoperative visual acuity of hand motions or worse. A MICOF keratoprosthesis significantly improved patients' visual function with bilateral end-stage corneal blindness. Postoperative visual acuity improved to 20/200 or better in 41 eyes (45.1%, of 91 eyes) and to 20/100 or better in 32 eyes (35.2% of 91 eyes) at the last follow-up visit. Preexisting glaucoma was present in 17 (18.7% of 91 eyes). The most common postoperative complications were overgrowth of the surface mucosa (31.9%, 29 of 91 eyes), glaucoma (25.3%, 23 of 91 eyes), retro-prosthetic membrane (15.4%, 14 of 91 eyes), keratoprosthesis device extrusion (15.4%, 14 of 91 eyes), superficial tissue thinning (14.3%, 13 of 91 eyes), endophthalmitis (13.2%, 12 of 91 eyes), titanium frame exposure (13.2%, 12 of 91 eyes), optical cylinder ante-displacement (13.2%, 12 of 91 eyes), cornea melting (7.7%, 7 of 91 eyes), retinal detachment (6.6%, 6 of 91 eyes) and aqueous humour leakage (2.2%, 2 of 91 eyes). 84.6% (77 of 91 eyes) of the eyes retained their initial keratoprosthesis at the latest follow-up.

CONCLUSIONS

A MICOF keratoprosthesis is a reliable approach to rescue vision in end-stage corneal blinded patients and has better retention than a Boston Kpro TypeⅡ.

3D bioprinting for artificial cornea: Challenges and perspectives

Corneal disease is one of the most important causes of blindness worldwide. Currently, the dominating treatment of corneal blindness is corneal transplantation. However, the main source of cornea for transplantation is based on donations which is far from enough to meet the requirement (less than 1:70 of cases). The severe shortage of donor cornea promotes the studies of effective corneal alternatives. However, many problems remain and can't be solved in current researches, such as original geometry reconstruction and ocular optical function restoring. 3D bioprinting can be a promising approach for corneal substitution. The advantages of this technology in corneal regeneration enable personalized corneal implant and single or multi-layer corneal equivalents with controllable structure and designed refractive ability. In this review, the progress, applications and limitations of most influential works among current keratoprosthesis and tissue-engineering cornea researches are discussed. Then the applications of 3D bioprinting in manufacturing multi-layered structures and surface are mentioned. Further, the potential, advantages in current research of 3D bioprinting single or multi-layer corneal equivalents and alternatives are discussed. Finally, an insight into the technical challenges and prospective facing the future research of 3D bioprinting corneal alternatives in vivo and in vitro is provided.

Corneal regeneration: A review of stromal replacements

Corneal blindness is traditionally treated by transplantation of a donor cornea, or in severe cases by implantation of an artificial cornea or keratoprosthesis. Due to severe donor shortages and the risks of complications that come with artificial corneas, tissue engineering in ophthalmology has become more focused on regenerative strategies using biocompatible materials either with or without cells. The stroma makes up the bulk of the corneal thickness and mainly consists of a tightly interwoven network of collagen type I, making it notoriously difficult to recreate in a laboratory setting. Despite the challenges that come with corneal stromal tissue engineering, there has recently been enormous progress in this field. A large number of research groups are working towards developing the ideal biomimetic, cytocompatible and transplantable stromal replacement. Here we provide an overview of the approaches directed towards tissue engineering the corneal stroma, from classical collagen gels, films and sponges to less traditional components such as silk, fish scales, gelatin and polymers. The perfect stromal replacement has yet to be identified and future research should be directed at combined approaches, in order to not only host native stromal cells but also restore functionality.

STATEMENT OF SIGNIFICANCE

In the field of tissue engineering and regenerative medicine in ophthalmology the focus has shifted towards a common goal: to restore the corneal stroma and thereby provide a new treatment option for patients who are currently blind due to corneal opacification. Currently the waiting lists for corneal transplantation include more than 10 million patients, due to severe donor shortages. Alternatives to the transplantation of a donor cornea include the use of artificial cornea, but these are by no means biomimetic and therefore do not provide good outcomes. In recent years a lot of work has gone into the development of tissue engineered scaffolds and other biomaterials suitable to replace the native stromal tissue. Looking at all the different approaches separately is a daunting task and up until now there was no review article in which every approach is discussed. This review does include all approaches, from classical tissue engineering with collagen to the use of various alternative biomaterials and even fish scales. Therefore, this review can serve as a reference work for those starting in the field and but also to stimulate collaborative efforts in the future.

Russian Keratoprosthesis in Stevens-Johnson Syndrome

PURPOSE

To evaluate the efficacy and safety of Moscow Eye Microsurgery Complex in Russia (MICOF) keratoprosthesis (KPro) implantation in patients with Stevens-Johnson syndrome (SJS).

METHODS

This was a retrospective case series. Fourteen eyes of 13 patients with SJS underwent KPro implantation at the Chinese People's Liberation Army General Hospital between April 1, 2000, and December 24, 2014. The visual outcome, KPro retention rate, and incidence of postoperative complications and their management were recorded and investigated.

RESULTS

The mean age and follow-up duration were 61.5 ± 17.3 years (range: 27-87 yrs) and 62 ± 39.1 months (range: 13-144 mo). Thirteen eyes (92.9%) achieved a best-corrected visual acuity of 20/200 or better, and 8 eyes (57.1%) achieved a best-corrected visual acuity of 20/40 or better after surgery. However, 71.4% (10/14) experienced visual decline because of different postoperative complications. Common complications included corneal melting, glaucoma, vitritis, superficial tissue overgrowth, and retroprosthetic membrane, and the incidence of these complications was 71.4%, 28.6%, 35.7%, 14.3%, and 28.6%, respectively. After repair and autoauricular cartilage reinforcement, all cases had stable anatomical retention at the last visit.

CONCLUSIONS

The MICOF KPro improved vision of patients with SJS, but lifelong surveillance is necessitated because of a high rate of postoperative complications. Corneal melting was the main reason for KPro failure. Infectious endophthalmitis and glaucoma were the main risk factors for visual loss.

Keratoprosthesis: A Review of Recent Advances in the Field

Since its discovery in the years of the French Revolution, the field of keratoprostheses has evolved significantly. However, the path towards its present state has not always been an easy one. Initially discarded for its devastating complications, the introduction of new materials and the discovery of antibiotics in the last century gave new life to the field. Since then, the use of keratoprostheses for severe ocular surface disorders and corneal opacities has increased significantly, to the point that it has become a standard procedure for corneal specialists worldwide. Although the rate of complications has significantly been reduced, these can impede the long-term success, since some of them can be visually devastating. In an attempt to overcome these complications, researchers in the field have been recently working on improving the design of the currently available devices, by introducing the use of new materials that are more biocompatible with the eye. Here we present an update on the most recent research in the field.

Idiopathic vitritis in the setting of Boston keratoprosthesis

PURPOSE

The aim of this study was to revisit the clinical paradigm attributed to Boston keratoprosthesis recipients presenting with idiopathic vitreous inflammation.

METHODS

A retrospective chart review was performed of keratoprosthesis recipients at Massachusetts Eye and Ear Infirmary, from January 2000 to August 2013, for demographic data, indication(s) for surgery, timing and presentation of vitreous inflammation, and best-corrected visual acuity at baseline, on presentation, and after resolution of vitritis.

RESULTS

Twenty-three (23 eyes) of 346 patients developed idiopathic vitreous inflammation after keratoprosthesis implantation. Six of 23 patients presented with signs and symptoms similar to infectious endophthalmitis but were culture negative. The proportion of patients who fit the previous paradigm of sudden painless loss of vision without external signs of infection ("sterile vitritis") at their first presentation with vitritis was only 4 of 23. Vision decline was variable (median, 9 lines on Snellen chart; range, 0-24), as was time to recovery of best vision (median, 8.9 weeks; range, 0.9-36.7). Nine eyes had repeat bouts (43 episodes in 23 patients). Ten of 43 episodes did not recover to baseline vision. Seventeen of 23 eyes with idiopathic vitritis after keratoprosthesis later developed other complications.

CONCLUSIONS

The current paradigm for idiopathic vitritis after keratoprosthesis implantation includes sudden painless loss of vision with full recovery of vision on treatment with periocular corticosteroids. However, idiopathic vitritis after keratoprosthesis can also mimic infectious endophthalmitis with pain and external signs of inflammation. Visual loss can be gradual. Vision may not recover to baseline despite treatment. Vitritis may be a part of a common pathway of chronic inflammation after keratoprosthesis.

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.

Effectiveness of transscleral cyclophotocoagulation as adjuvant therapy for refractory glaucoma in keratoprosthesis patients

PURPOSE

To evaluate the efficacy and safety of diode laser transscleral cyclophotocoagulation (DLTSC) as an adjuvant therapy to treat refractory glaucoma diagnosed before or after Moscow Eye Microsurgery Complex (MICOF) keratoprosthesis surgery.

METHODS

Fifteen patients underwent unilateral DLTSC to treat refractory glaucoma diagnosed before or after undergoing MICOF keratoprosthesis surgery. The cause for keratoprosthesis was alkali burn in 8 patients (53.33%); thermal burn, sulfuric acid burn, and Steven-Johnson syndrome in 2 patients (13.33%) each; and ocular cicatricial pemphigoid in 1 patient (6.67%). Best-corrected visual acuity (BCVA), intraocular pressure (IOP), any medications, and adverse events were recorded before DLTSC and on postoperative day 7; months 1, 3, and 6; and every 6 months afterwards.

RESULTS

The patients were followed up for an average of 13.15 ± 9.35 months. The IOP was significantly less at postoperative months 6, 12, 24, and 36. There were no changes in BCVA after DLTSC. No significant changes in medication to treat ocular hypertension were prescribed.

CONCLUSIONS

Diode laser transscleral cyclophotocoagulation is an effective treatment option for refractory glaucoma and can be used as a therapy adjuvant to keratoprosthesis. Long-term effects require further clinical observation.

An improved biofunction of Titanium for keratoprosthesis by hydroxyapatite-coating

Titanium framework keratoprosthesis has been commonly used in the severe corneal blindness, but the tissue melting occurred frequently around titanium. Since hydroxyapatite has been approved to possess a good tissue integration characteristic, nanostructured hydroxyapatite was coated on the surface of titanium through the aerosol deposition method. In this study, nanostructured hydroxyapatite coating was characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, and auger electronic spectrometer. Biological evaluations were performed with rabbit cornea fibroblast in vitro and an animal model in vivo. The outcomes showed the coating had a grain-like surface topography and a good atomic mixed area with substrate. The rabbit cornea fibroblasts appeared a good adhesion on the surface of nanostructured hydroxyapatite in vitro. In the animal model, nanostructured hydroxyapatite-titanium implants were stably retained in the rabbit cornea, and by contrast, the corneal stroma became thinner anterior to the implants in the control. Therefore, our findings proved that nanostructured hydroxyapatite-titanium could not only provide an improved bond for substrate but also enhance the tissue integration with implants in host. As a promising material, nanostructured hydroxyapatite-titanium–based keratoprosthesis prepared by the aerosol deposition method could be utilized for the corneal blindness treatment.

Implantation of Iakymenko keratoprosthesis in patients with severe ocular injury

AIM

To present the results of implantation of Iakymenko keratoprosthesis in five patients with vascularized corneal leukoma caused by severe ocular injury.

METHODS

Iakymenko keratoprosthesis was implanted into 5 eyes of 5 patients: 4 patients were suffered from chemical burns and 1 patient from explosive injury. The preoperative visual acuity ranged from light perception to hand motion. The implantation surgery was composed of two-stage procedures. The follow-up period was from 9 months to 11 years. The outcome measures were visual acuity, retention, and complications of the keratoprosthesis.

RESULTS

Vision improvements were achieved in most patients. All keratoprosthesis were retained within the follow-up period. Corneal melting occurred in one patient and fibrous closure in another patient, both of which were successfully treated. Retinal detachment occurred in one patient after surgery.

CONCLUSION

Iakymenko keratoprosthesis seems to be a promising alternative for the patients with severe corneal injury, but further investigation is needed to evaluate the role of Iakymenko keratoprosthesis.