Standards for Modified Osteoodontokeratoprosthesis (OOKP) Surgery According to Strampelli and Falcinelli

Long-Term Outcomes of Keratoprosthesis With Biological Haptic: A Review of 25 Years of Single-Center Surgeries

PURPOSE

To study the outcome of eyes that underwent surgery for keratoprosthesis with a biological haptic, osteo-odonto-keratoprosthesis (OOKP) or tibia keratoprosthesis, by a single surgeon over a time span of more than 25 years.

METHODS

One hundred thirty eyes that had received a keratoprosthesis with a biological haptic between 1994 and 2022 by a single surgeon were included in this retrospective analysis. Main outcome parameters were postoperative best corrected visual acuity, postoperative refractive error, postoperative complications, anatomical and functional survival of the prosthesis as well as comparison of subgroups of the 2 different types (OOKP n = 78; tibia keratoprosthesis n = 52) of keratoprostheses, and subgroup analysis of different indications for surgery. Patients were examined every 6 months.

RESULTS

The longest follow-up was 25.8 years. Reasons for implantation were graft-vs-host disease (6.9%), vascularized corneas and dry eye (22.9%), physical or chemical burns (29.8%), Stevens-Johnson syndrome (9.9%), and ocular cicatricial pemphigoid (30.5%). The functional success rate with postoperative visual acuity of better than 0.7 log MAR was achieved by 56.9%. The OOKP subgroup showed a better mean visual outcome. 14 keratoprostheses (10.7%) had to be explanted over the whole time span. In the time leading to explantation, refraction showed a statistically significant myopic shift when compared with the non-explanted prosthesis. Anatomical survival rates were better for the OOKP in the first 12 years after implantation.

CONCLUSIONS

The study shows that keratoprosthesis with a biological haptic has favorable long-term outcomes. The retention rate stayed very high with excellent functional outcomes.

Future directions in managing aniridia-associated keratopathy

Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management. Here, we review the current understanding about the pathogenesis and management of AAK. We highlight the biological mechanisms involved in AAK development with the aim to develop future treatment options, including surgical, pharmacological, cell therapies, and gene therapies.

Use of Endoscopy in Keratoprostheses with Biological Haptics

INTRODUCTION

In severe ocular surface disease where penetrating keratoplasty cannot be successfully performed, implantation of a keratoprosthesis can achieve visual rehabilitation. Osteo-odonto-keratoprosthesis offers good tissue integration due to its biological haptics, resulting in a better survival rate and lower extrusion rate. Due to corneal opacity, which is often complete, assessing the potential visual acuity is challenging. Also, during implantation of a keratoprosthesis or during later intraocular revision surgery, there is a limited field of view of the peripheral retina or ciliary body region. This is due to the small size and central location of the prosthesis optics and the geometric conditions of the prosthetic haptics. These factors can complicate surgery.

METHODS

Endoscopic video assistance was used in 7 eyes of 6 different patients (6 male, 2 female, mean age 66 ± 9 years). In 3 eyes the indication was for preoperative estimation of potential visual acuity during a 23 G vitrectomy. In 2 eyes it was used during implantation surgery itself, and in 2 eyes it was used during revision surgery and vitrectomy. An endoscope with semirigid optics and an image guidance system with 3,000 pixels and 70°field of view from PolyDiagnost was used, with a 23 G trocar system.

RESULTS

Endoscopy was successfully applied in all eyes examined. In 1 of 3 eyes where endoscopy was performed to estimate the visual acuity potential, a keratoprosthesis was subsequently planned. In the other two eyes, the visual acuity potential was rated insufficient for future keratoprosthesis surgery. Detailed assessment of the retina and optic disc was limited to gross pathologies because of low image resolution. During implantation, it was possible to visualize correct positioning of the posterior haptic behind the host cornea. Retroprosthetic membranes could successfully be removed by endoscopy-assisted vitrectomy.

CONCLUSION

Endoscopy assistance offers advantages in visualization both for determining the indication for KPro surgery, during implantation, and in the management of complications after implantation of a keratoprosthesis. Low resolution of the imaging system places limits on assessment capabilities. Although technical improvements and miniaturization may enhance its future capabilities, endoscopy in its current form is already a valuable addition in the context of keratoprosthesis surgery.

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.

Timing of glaucoma treatment in patients with MICOF: A retrospective clinical study

Purpose

To summarize and discuss the treatment and timing of glaucoma in patients with MICOF keratoprosthesis implantation to guide follow-up clinical treatment.

Methods

The data of 39 eyes (39 patients) with the Moscow Eye Microsurgery Complex in Russia (MICOF) keratoprosthesis implantation in our hospital from 1 January 2002 to 31 December 2017 were collected, including patients with preexisting glaucoma and those who developed glaucoma de novo after MICOF. The sex, age, preoperative diagnosis, glaucoma surgery, keratoplasty, times of keratoplasty, best corrected visual acuity (BCVA) and final follow-up corrected visual acuity, visual field (VF) defect, and cup-to-disk ratio (CDR) were statistically analyzed.

Results

Among 16 eyes with preexisting glaucoma, eight eyes underwent glaucoma surgery before MICOF, 4 eyes underwent glaucoma surgery combined with MICOF, and four eyes were managed medically. Among 23 eyes with de novo glaucoma, seven eyes were treated with surgery and 16 eyes were treated with medication only. A total of 9 (56.3%) eyes had corneal transplants with preexisting glaucoma, which was a higher percentage than that in the patients with de novo glaucoma (n = 5, 21.7%, P = 0.043). In both the preexisting glaucoma group and the de novo glaucoma group, the most common causes were alkali burns (56.3% of preexisting glaucoma and 43.5% of de novo glaucoma). There was no significant difference between the operation and initial visual acuity, postoperative visual acuity, BCVA, CDR, or VF defect. In the de novo glaucoma group, the final follow-up visual acuity of the glaucoma surgery group (1.56 ± 1.07) was worse than that of the mediation group (0.44 ± 0.53) (P < 0.017). Among the complications, the incidence of cornea melting in the patients treated with medications only (n=10) was significantly higher than that in the patients treated with glaucoma surgery (n = 0, P = 0.007), but there was no significant difference in the other complications.

Conclusion

Among patients with MICOF, those patients who have undergone keratoplasty are more likely to develop glaucoma before surgery and glaucoma needs to be prevented. Surgical treatment can be selected according to the ocular surface condition in the patients with de novo glaucoma to reduce the occurrence of complications.

Osteo-odonto-keratoprosthesis according to Strampelli original technique: A retrospective study with up to 30 years of follow-up

PURPOSE

To describe clinical, anatomical, and visual outcomes obtained from a long-term follow-up of 59 patients who underwent osteo-odonto-keratoprosthesis (OOKP) using the original Strampelli technique.

DESIGN

retrospective clinical cohort study.

METHODS

82 eyes of 59 patients who underwent OOKP surgery between 1969 and 2011 were included. Patients' clinical characteristics before surgery as well as complications and further surgeries until the end of follow-up were recorded. BCVA was revised before surgery and at 1 month, 1 year and every 5 years until the 30th year of follow-up.

RESULTS

Mean follow-up post-OOKP was 27.4±11.2 years (2.4-52). The most frequent cause of blindness was chemical injuries (71%). OOKP integrity was maintained in 77 out of 82 eyes until the end of follow-up (94%). Excluding the cataract, acquired glaucoma was the most frequent complication with a prevalence at 10 years of 36%. Mean BCVA improved from 2.60±0.32 at presentation to 0.40±0.65 at 1 year and 1.21±1.19 logMAR at 30 years. Overall, 51% of the included eyes attained a BCVA better than 0.05 logMAR and a stabilization of BCVA was observed for the first 10 years of follow-up post-OOKP. Better BCVA outcomes were observed in the Stevens-Johnson Syndrome or Toxic Epidermal Necrolysis (SJS/TEN) group, while glaucoma showed not to significantly affect visual acuity.

CONCLUSIONS

The original OOKP still represents a valid surgical choice, durable over time, for restoring vision in end-stage corneal blindness patients not eligible for a corneal transplant.

Current Perspectives on Corneal Transplantation (Part 2)

Disease of the cornea is the third leading cause of blindness worldwide. Corneal graft surgery is one of the most successful forms of solid organ transplantations in humans, with ever increasing developments in surgical technique. To date, approximately 4504 corneal transplants are performed in the UK each year. While full thickness transplantation was the most commonly performed keratoplasty over the last few decades, selective lamellar transplantation of the diseased layers of the cornea has been universally adopted. This comprehensive review aims to provide an updated synthesis on different types of corneal transplantations, their treatment outcomes, and the associated complications of each procedure both in adult and pediatric populations. In addition, we also present an up-to-date summary of the emerging therapeutic approaches that have the potential to reduce the demand for donor-dependent keratoplasty.

Global Consensus on the Management of Limbal Stem Cell Deficiency

PURPOSE

In recent decades, the medical and surgical treatment of limbal stem cell deficiency (LSCD) has evolved significantly through the incorporation of innovative pharmacological strategies, surgical techniques, bioengineering, and cell therapy. With such a wide variety of options, there is a need to establish a global consensus on the preferred approaches for the medical and surgical treatment of LSCD.

METHODS

An international LSCD Working Group was established by the Cornea Society in 2012 and divided into subcommittees. Four face-to-face meetings, frequent email discussions, and teleconferences were conducted since then to reach agreement on a strategic plan and methods after a comprehensive literature search. A writing group drafted the current study.

RESULTS

A consensus in the medical and surgical management of LSCD was reached by the Working Group. Optimization of the ocular surface by eyelid and conjunctival reconstruction, antiinflammatory therapy, dry eye and meibomian gland dysfunction treatment, minimization of ocular surface toxicity from medications, topical medications that promote epithelialization, and use of a scleral lens is considered essential before surgical treatment of LSCD. Depending on the laterality, cause, and stage of LSCD, surgical strategies including conjunctival epitheliectomy, amniotic membrane transplantation, transplantation of limbal stem cells using different techniques and sources (allogeneic vs. autologous vs. ex vivo-cultivated), transplantation of oral mucosal epithelium, and keratoprosthesis can be performed as treatment. A stepwise flowchart for use in treatment decision-making was established.

CONCLUSIONS

This global consensus provides an up-to-date and comprehensive framework for the management of LSCD.

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.

Surgical Management of Limbal Stem Cell Deficiency

Treatment of limbal stem cell deficiency is challenging. Multiple options can be adopted according to the underlying cause and the patient and physician preferences. Stem cell transplant is a common treatment modality and several techniques have been described with outcomes varying by the laterality of the condition. Keratoprosthesis is a preferred option for bilateral conditions. Indications for type 1 and type 2 keratoprosthesis differ and the past 2 decades have seen a revolution in the field of keratoprosthesis with encouraging and improved outcomes. Management also includes preventive measures and measures to optimize/stabilize the ocular surface that would go a long way in reducing the deterioration of the ocular surface. The aim of this review is to provide an overview of the currently available techniques and to present a comprehensive algorithm to assist in decision making for unilateral and bilateral limbal stem cell deficiency.

Biomimetic bone-like composites as osteo-odonto-keratoprosthesis skirt substitutes

Osteo-odonto-keratoprostheses, incorporating dental laminate material as an anchoring skirt around a central poly(methyl methacrylate) (PMMA) optic, have been used to replace the cornea for many years. However, there are many intricacies associated with the use of autologous dental laminate material, surgical complexity and skirt erosion. Tissue engineering approaches to bone replacement may offer suitable alternatives in osteo-odonto-keratoprosthesis (OOKP) surgery. In this study, a hydrogel polymer composite was investigated as a synthetic substitute for the OOKP skirt. A novel high strength interpenetrating network (IPN) hydrogel composite with nano-crystalline hydroxyapatite (nHAp) coated poly (lactic-co-glycolic acid) PLGA microspheres was created to mimic the alveo-dental lamina by employing agarose and poly(ethylene glycol) diacrylate (PEGDA) polymers. The incorporation of nHAp coated PLGA microspheres into the hybrid IPN network provide a micro-environment similar to that of skeletal tissues and improve cellular response. Agarose was used as a first network to encapsulate keratocytes/3T3 fibroblasts and PEGDA (6000 Da) was used as a second network with varying concentrations (20 and 40 wt %) to produce a strong and biocompatible scaffold. An increased concentration of either agarose or PEG-DA and incorporation of nHAp coated PLGA microspheres led to an increase in the elastic modulus. The IPN hydrogel combinations supported the adhesion and proliferation of both fibroblast and ocular human keratocyte cell types during in in-vitro testing. The cells endured the encapsulation process into the IPN and remained viable at 1 week post-encapsulation in the presence of nHAp coated microspheres. The material did not induce significant production of inflammatory cytokine IL-6 in comparison to a positive control (p < 0.05) indicating non-inflammatory potential. The nHAp encapsulated composite IPN hydrogels are mechanically strong, cell supportive, non-inflammatory materials supporting their development as OOKP skirt substitutes using a new approach to dental laminate biomimicry in the OOKP skirt material.

Endophthalmitis in Eyes with Osteo-odonto Keratoprosthesis

Aim: To analyze the incidence, microbiological profile, risk factors, and outcomes in eyes with osteo-odonto keratoprosthesis (OOKP) developing endophthalmitis.Methods & material: Retrospective review of medical records of patients presenting between 2003 and 2013 with OOKP and endophthalmitis was undertaken after obtaining IRB approval. Patient demographics, clinical features, microbiological evaluation, treatment details, and outcomes were analyzed.Results: Of 92 eyes with OOKP, 8 (9%) had endophthalmitis. Indications for OOKP included Steven-Johnson syndrome (SJS; n = 6; 75%) and chemical injuries (n = 2; 25%). The mean duration from OOKP surgery to endophthalmitis was 49.4 ± 32.3 months. Seven of eight eyes had associated laminar resorption. Endophthalmitis resolved with conservative management in three eyes. Lamina removal was required in three eyes; one eye underwent evisceration. At presentation, mean BCVA was 2.76 ± 0.24 logMAR that improved to 2.48 ± 1.0 logMAR after intervention. Mean follow-up was 12.6 ± 13.2 months.Conclusion: Endophthalmitis portends a grave prognosis for eyes with OOKP. The most important risk factors are SJS (75%) and lamina resorption (88%).

Management Strategies of Ocular Chemical Burns: Current Perspectives

Ocular chemical burns are absolute ophthalmic emergencies and require immediate management to minimize devastating sequelae. Management of alkali and acid burns is started at the scene of the accident by copious irrigation. Treatment is directed at improving epithelial integrity and stromal stability, reduction of undue inflammation, and prevention or timely management of complications. To ascertain the best possible outcome, numerous biological medications and surgical interventions have been merged into conventional therapeutic regimens. These include autologous and umbilical cord serum preparations, platelet-rich plasma, amniotic membrane transplantation, limbal stem-cell transplantation, and anti-angiogenic agents.

Oral mucosa grafting in periorbital reconstruction

To provide an extensive literature review on the clinical indications of oral mucosa grafts (OMG) and minor salivary gland grafts (MSGG) in periorbital reconstruction together with safe practice graft harvesting techniques to minimize donor-site morbidity. A literature review was performed by searching the databases of PUBMED, EMBASE, and COCHRANE library using the keywords: minor salivary glands; oral mucosal graft; orbit; and eye. The bibliographies of the pertinent articles were examined for additional papers. Indications for OMG include treatment of recurrent pterygia; socket contracture in anophthalmic patients; repair of eyelid deformities; ocular surface and fornix reconstruction following tumour resection, cicatricial ocular surface disorders, or chemical burns. More novel uses include repair of glaucoma aqueous drainage device erosions or leaking trabeculectomy blebs; scleral buckle exposure; and keratoprosthesis-related corneal melts as well as lining the dacryocystorhinostomy tract to prevent closure. Simultaneous MSGG transplantation may be used in the treatment of severe dry eyes or dry anophthalmic cavities. Harvesting from the inner cheek is preferred to lower lip as it causes less post-operative discomfort and neurosensory deficits. Suturing is recommended for smaller ovoid grafts as it allows less painful closure without tension, while larger rectangular defects are best left to heal by secondary intention. OMG and MSGG transplantation is a viable alternative to replace conjunctiva and restore the ocular surface. The donor site is readily accessible and widely available in most patients, grafting is fast and cheap, and the same site may undergo repeated harvesting with few donor site complications.

Keratoprosthesis: Current global scenario and a broad Indian perspective

Keratoprosthesis (Kpro) forms the last resort for bilateral end-stage corneal blindness. The Boston Type 1 and 2 Kpros, the modified osteo-odonto Kpro and the osteo-Kpro are the more frequently and commonly performed Kpros, and this review attempts to compile the current data available on these Kpros worldwide from large single-center studies and compare the indications and outcomes with Kpros in the Indian scenario. Although the indications have significantly expanded over the years and the complications have reduced with modifications in design and postoperative regimen, these are procedures that require an exclusive setup, and a commitment toward long-term follow-up and post-Kpro care. The last decade has seen a surge in the number of Kpro procedures performed worldwide as well as in India. There is a growing need in our country among ophthalmologists to be aware of the indications for Kpro to facilitate appropriate referral as well as of the procedure to enable basic evaluation during follow-ups in case the need arises, and among corneal specialists interested to pursue the field of Kpros in understanding the nuances of these surgeries and to make a judicious decision regarding patient and Kpro selection and more importantly deferral.

Osteo-odonto keratoprosthesis: Innovative dental and ophthalmic blending

Corneal diseases are among the major causes of global blindness, secondary to cataract. osteo-odonto keratoprosthesis (OOKP) is the ideal treatment for patients with end-stage inflammatory corneal diseases where a portion of tooth along with bone is used to support an optical cylinder to restore vision in such patients. OOKP surgery requires multidisciplinary approach involving dentists, ophthalmologists, and radiologists. Very less is known in dentistry about the role of the periodontium in the field of ophthalmology. This paper highlights OOKP indications, contraindications, surgical procedure, role of oral structures, advantages, and limitations.

Piezoelectric harvest of osteo-odonto-lamina in modified osteo-odonto keratoprosthesis: A maxillofacial perspective

Purpose:

We describe the piezo-osteotomy feasibility in rehabilitation and harvesting of osteo-odonto lamina in modified osteo-odonto keratoprosthesis (MOOKP) surgery. Surgery was evaluated regarding operative technique and success of the keratoprosthesis (KPros) in terms of perception to light (+ve) to finger counting (+ve).

Materials and Methods:

This retrospective cohort study included 12 patients undergone MOOKP surgery procedures. Harvesting of osteo-odonto-lamina was performed using piezosurgical osteotomy during 2007–2012.

Results:

The mean follow up was 34 months (range 24–48 months). Of the 12 patients six patients had vision ≥6/12, four patients had vision <6/12, but >6/60 and one patients had vision ≤6/60. KPros was retained and functional in all the eyes after a minimum follow up of 24 months. There was mucosal overgrowth over the optical cylinder occurred in two cases over 4 years follow up which was corrected with trimming. Postoperative complication at donor site was seen in three cases, two cases with exposure of root of adjacent teeth and oro antral fistula in one.

Conclusions:

This study suggests that piezoelectric harvest of osteo-odonto-lamina is a valuable surgical option in patients undergoing MOOKP surgery, resulting in high success rate with less complication.

[Health-related quality of life after implantation of a keratoprosthesis with biological haptic]

BACKGROUND

Many studies report comparatively good long-term results among patients with keratoprostheses with biological haptic. However, overall costs are correspondingly high. A clear cost-benefit relationship is therefore desirable.

OBJECTIVE

This study investigates health-related quality of life after implantation of a keratoprosthesis with biological haptic.

MATERIALS AND METHODS

We present a retrospective analysis of medical data of 25 patients treated between 1996 and 2006 at the Department of Ophthalmology, University Hospital Homburg/Saar and the Klinikum Offenburg. Health-related quality of life was assessed by means of a questionnaire based on validated instruments, with particular emphasis on physical symptoms, mental health, functional limitations, and social interactions.

RESULTS

At a patient age of 49.8 ± 15.7 years (minimum-maximum: 19-78 years; 6 female, 19 male), the mean duration of corneal blindness was 13.8 ± 13.1 years (minimum-maximum: 1-47 years). Changes in visual acuity and subjective satisfaction were statistically significant (p <0.001). Quality of life (on a scale of 1 to 6: median 2) at the time "before the onset of eye disease" and ≥15 months after surgery were identical. Patients with a postoperative visual acuity ≤0.1 (n =11) also showed a statistically significant (p =0.016) benefit in this context.

CONCLUSION

The expenditures and costs of keratoprosthetics can be justified by an improvement in the health-related quality of life of the persons concerned. Even a postoperative visual acuity of ≤0.1 correlates with a statistically significant improvement in the subjective quality of life of these patients.

RESULTS OF RETINAL DETACHMENT SURGERY IN EYES WITH OSTEO-KERATOPROSTHESIS

PURPOSE

To evaluate the anatomical and functional results of pars plana vitrectomy in eyes with osteo-keratoprosthesis, who have suffered retinal detachment.

METHODS

An observational, retrospective study of 18 eyes which underwent pars plana vitrectomy for retinal detachment after an implantation of an osteo-keratoprosthesis, with a minimum of 1-year follow-up. A descriptive study and a Kaplan-Meier survival analysis for anatomical and functional success were performed. Anatomical success was defined as an attached retina at the end of vitreoretinal surgery with no redetachment during the follow-up. Functional success was defined as a postoperative visual acuity of more than or equal to 20/400.

RESULTS

The overall rate of anatomical success was 56%, and the anatomical survival rates were 67% and 53% at 6 months and 12 months, respectively, maintaining this last value at 24 months after pars plana vitrectomy. The overall rate of functional success was 17%, and the functional survival rates were 83%, 39%, and 14% at 6 months, 12 months, and 24 months after pars plana vitrectomy, respectively. The most frequent complication after retinal surgery was retroprosthetic membrane (33%).

CONCLUSION

Despite the reserved prognosis and the severe complications, vitrectomy represents a valid method for treating retinal detachment in patients with osteo-keratoprosthesis, with good anatomical results but poor visual acuity.

Glaucoma after corneal replacement

Glaucoma is a well-known complication after corneal transplantation surgery. Traditional corneal transplantation surgery, specifically penetrating keratoplasty, has been slowly replaced by the advent of new corneal transplantation procedures: primarily lamellar keratoplasties. There has also been an emergence of keratoprosthesis implants for eyes that are high risk of failure with penetrating keratoplasty. Consequently, there are different rates of glaucoma, pathogenesis, and potential treatment in the form of medical, laser, or surgical therapy.

Chondro-Keratoprosthesis: An Alternative to OOKP?

Purpose

To evaluate the use of cartilage as a potential graft material toward osteo-odontal tissue replacement in keratoprosthesis surgery.

Methods

We describe a modification of the osteo-odonto-keratoprosthesis surgery that involves the use of autologous auricular conchal cartilage graft (ACCG). In stage 1a, a full-thickness cheek mucosa graft was performed over the ocular surface. In stage 1b, ACCG was harvested via a retroauricular approach. An optical polymethyl-methacrylate cylinder was embedded into a double-layered fragment of cartilage and secured by cyanoacrylate glue. The graft is then placed in a infraorbital pocket. Stage 2, performed after 3 months, involved retrieval of the complex and implantation after reflection of the mucosal flap, corneal trephination, iris and lens removal and anterior vitrectomy.

Results

We report two cases of chondro-keratoprosthesis (CKPRO) who underwent surgery with up to 15 months of follow-up. Preoperatively, vision was limited to light perception (LP) in both cases. On patient 1, CKPRO was performed in the right eye and the postoperative visual acuity stay limited to LP related to preoperative retinal lesions. On patient 2, CKPRO was performed in the left eye and the vision was improved to 20/100 J6. No postoperative complications such as extrusion, epithelial downgrowth, retrocorneal membrane or endophtalmia were observed.

Conclusions

ACCG could be an interesting alternative to replace osteo-odontal graft in keratoprosthesis surgery. However, further comprehensive studies with larger sample size and longer follow-up are required. However longer follow-up and a higher number of patient are required to report postoperative complications incidence, survival and functional outcomes.

The Ocular Surface and How It Can Influence the Outcomes of Keratoprosthesis

Severe ocular diseases may result in partial or complete limbal cell deficiency. Besides conservative options, treatment options include conjunctival replacement procedures and limbal autografting. Limbal allografts are an option in patients with bilateral limbal cell deficiency. In many of these cases, a keratoprosthesis (KPro) is the last option to restore functional vision in patients with severe corneal blindness with no other options.

Current and Upcoming Therapies for Ocular Surface Chemical Injuries

Chemical injuries frequently result in vision loss, disfigurement, and challenging ocular surface complications. Acute interventions are directed at decreasing the extent of the injury, suppressing inflammation, and promoting ocular surface re-epithelialization. Chronically, management involves controlling inflammation along with rehabilitation and reconstruction of the ocular surface. Future therapies aimed at inhibiting neovascularization and promoting ocular surface regeneration should provide more effective treatment options for the management of ocular chemical injuries.

Periodontium bestows vision!!

The role of periodontium in supporting the tooth structures is well-known. However, less is known about its contribution to the field of ophthalmology. Corneal diseases are among major causes of blindness affecting millions of people worldwide, for which synthetic keratoprosthesis was considered the last resort to restore vision. Yet, these synthetic keratoprosthesis suffered from serious limitations, especially the foreign body reactions invoked by them resulting in extrusion of the whole prosthesis from the eye. To overcome these shortcomings, an autologous osteo-odonto keratoprosthesis utilizing intraoral entities was introduced that could positively restore vision even in cases of severely damaged eyes. The successful functioning of this prosthesis, however, predominantly depended on the presence of a healthy periodontium for grafting. Therefore, the following short communication aims to acknowledge this lesser-known role of the periodontium and other oral structures in bestowing vision to the blind patients.

Long-term Visual Outcomes and Complications of Boston Keratoprosthesis Type II Implantation

PURPOSE

To report the long-term visual outcomes and complications after Boston keratoprosthesis type II implantation in the largest single-center case series with the longest average follow-up.

DESIGN

Retrospective review of consecutive clinical case series.

PARTICIPANTS

Between January 1992 and April 2015 at the Massachusetts Eye and Ear Infirmary, 48 eyes of 44 patients had keratoprosthesis type II implanted by 2 surgeons (C.H.D. and J.C.).

METHODS

For each eye, data were collected and analyzed on the preoperative characteristics, intraoperative procedures, and postoperative course.

MAIN OUTCOME MEASURES

Visual acuity outcomes, postoperative complications, and device retention.

RESULTS

The most common indications for surgery were Stevens-Johnson syndrome in 41.7% (20 of 48 eyes) and mucous membrane pemphigoid in 41.7% (20 of 48 eyes). Mean follow-up duration was 70.2 months (standard deviation, 61.8 months; median, 52 months; range, 6 months to 19.8 years). Almost all patients (95.8%, 46 of 48 eyes) had a preoperative visual acuity of 20/200 or worse. Postoperative visual acuity improved to 20/200 or better in 37.5% (18 of 48 eyes) and to 20/100 or better in 33.3% (16 of 48 eyes) at the last follow-up visit. The most common postoperative complication was retroprosthetic membrane formation in over half (60.4%, 29 of 48 eyes). The most pressing postoperative complication was glaucoma onset or progression in about a third. Preexisting glaucoma was present in 72.9% (35 of 48 eyes). Glaucoma progressed in 27.1% (13 of 48 eyes) and was newly diagnosed in 8.3% (4 of 48 eyes) after surgery. Other postoperative complications were tarsorrhaphy revision in 52.1% (25 of 48 eyes), retinal detachment in 18.8% (9 of 48 eyes), infectious endophthalmitis in 6.3% (3 of 48 eyes), and choroidal detachment or hemorrhage in 8.3% (4 of 48 eyes). Half of eyes retained their initial keratoprosthesis at the last follow-up (50.0%, 24 of 48 eyes).

CONCLUSIONS

The Boston keratoprosthesis type II is a viable option to salvage vision in patients with poor prognosis for other corneal procedures. Retroprosthetic membranes, keratoprosthesis retention, and glaucoma are major challenges in the postoperative period; however, the keratoprosthesis can still provide improved vision in a select group of patients.

Osteokeratoprosthesis Using Tibial Bone: Surgical Technique and Outcomes

PURPOSE

To analyze the anatomical and functional results of keratoprosthesis using tibial bone autograft.

METHODS

We reviewed 113 charts of patients who underwent tibial bone osteokeratoprothesis implantation at the Centro de Oftalmologia Barraquer. Kaplan-Meier survival curves with 95% confidence interval were calculated for functional success, defined as best corrected visual acuity (BCVA) ≥0.05 on the decimal scale, and for anatomical success, defined as retention of the keratoprosthesis lamina. Multivariate analysis was used to test the impact of clinical factors on anatomical and functional survival rates.

RESULTS

Based on Kaplan-Meier analyses, tibial bone keratoprosthesis 5-year and 10-year anatomical survival rates were 69.5% and 53.5%, respectively. Functional survival rate at 5 years was 33% and at 10 years was 19.2%. Considering primary diagnosis, chemical burn had better anatomical and functional survival rates than autoimmune or infectious diseases. Patient age did not have a significant effect on keratoprosthesis survival rates. About 48.7% of the patients who underwent surgery had complications: keratoprosthesis extrusion, glaucoma, retinal detachment and buccal mucosa necrosis were the most frequent ones.

CONCLUSION

Half of the patients with tibial bone KPro had retained the keratoprosthesis after 10 years post-surgery and one-fifth of them had visual acuity of 0.05 or better at the same period. Considering that these patients have no other way to recover their vision either because they have no canine tooth or their buccal or dental conditions are not adequate for OOKP, this modified surgery is their only hope.

Treatment Modalities and Clinical Outcomes in Ocular Sequelae of Stevens-Johnson Syndrome Over 25 Years--A Paradigm Shift

PURPOSE

To highlight and compare the outcomes of management for the ocular sequelae of Stevens-Johnson syndrome (SJS) over 25 years in a tertiary eye care institute.

METHODS

A retrospective chart review of 798 eyes of 399 patients with SJS evaluated between January 1990 and December 2004 (group I) and of 847 eyes of 517 patients between January 2005 and December 2014 (group II) was done. The primary and secondary outcome measures were a change in the best-corrected visual acuity (BCVA) and an improvement in the symptoms and the ocular surface status, respectively. The groups were subdivided into procedures for ocular surface stabilization (A) and visual rehabilitation (B) and those managed conservatively (C).

RESULTS

In the subgroup A of group II, an improvement/stabilization of BCVA after punctal cautery (231 eyes), mucous membrane grafting for lid margin keratinization (393 eyes), and fornix reconstruction (28 eyes) was noted in 93.6% of eyes. In subgroup B, all 10 eyes that underwent limbal allograft in group I failed when compared with an improvement of BCVA to better than 20/200 in 65.5% of the 61 eyes that underwent keratoprostheses. It was noted that the limbal status worsened in 66.9% of eyes treated conservatively in group I.

CONCLUSIONS

Stabilization procedures show a beneficial role while conservative management can lead to deterioration in chronic ocular sequelae of SJS. Keratoprosthesis, specifically the modified osteo-odonto-keratoprosthesis, forms the mainstay for visual rehabilitation in the end-stage disease. This study highlights the improved outcomes with a paradigm shift in the management modalities.

Stevens-Johnson syndrome: The role of an ophthalmologist

Stevens-Johnson syndrome (SJS) is an acute blistering disease of the skin and mucous membranes. Acute SJS leads to the acute inflammation of the ocular surface and chronic conjunctivitis. If not properly treated, it causes chronic cicatricial conjunctivitis and cicatricial lid margin abnormalities. Persistent inflammation and ulceration of the ocular surface with cicatricial complications of the lids leads to chronic ocular sequelae, ocular surface damage, and corneal scarring. The destruction of the glands that secrete the tear film leads to a severe form of dry eye that makes the management of chronic SJS difficult. The option that is routinely used for corneal visual rehabilitation, keratoplasty, is best avoided in such cases. We describe the management strategies that are most effective during the acute and chronic stages of SJS. Although treatments for acute SJS involve immunosuppressive and immunomodulatory therapies, amniotic membrane transplantation is also useful. The options for visual rehabilitation in patients with chronic SJS are undergoing radical change. We describe the existing literature regarding the management of SJS and highlight recent advances in the management of this disorder.

[Current treatment options with artificial corneas: Boston Kpro, Osteo-odontokeratoprosthesis, Miro Cornea® and KeraKlear®]

BACKGROUND

Although corneal transplant surgery in avascular normal risk eyes is becoming even more minimally invasive and successful, treatment options for difficult to treat patients with high risk eyes are still limited. In these cases HLA typed allogeneic transplants and artificial corneas (keratoprostheses) can be used.

METHODS

This article combines a review of the literature in PubMed and own clinical experiences on the use of artificial corneas in high risk eyes. Osteo-odontokeratoprosthesis (OOKP), Boston Kpro, Miro Cornea® and KeraKlear® corneas were used as clinical keratoprostheses.

RESULTS

Worldwide, the most experience exists for the use of Boston Kpro and OOKP in high risk eyes. Miro Cornea® and KeraKlear® are new procedures where only preliminary results are available and further evaluation is necessary. The longest experience and best anatomical long-term results have been achieved with OOKPs. Comparable cohorts are available for the Boston Kpro. The function of all keratoprostheses is threatened by secondary glaucoma. Implantation of the KeraKlear® prosthesis remains difficult. The Miro Cornea® shows an initially stable integration behavior.

CONCLUSION

Keratoprostheses, such as the Boston Kpro and OOKP are valid treatment options for eyes which are not open to therapy with allogeneic corneal transplantation. Modern implants such as KeraKlear® prosthesis and Miro Cornea® need further prospective clinical evaluation.

Corneal transplantation and glaucoma

Glaucoma is the leading cause of irreversible vision loss post-keratoplasty and an important cause of graft failure. With newer techniques, such as lamellar, endothelial, and laser-assisted keratoplasty as well as keratoprosthesis gaining popularity, clinicians will need to consider the incidence, risks, evaluation, and management of glaucoma for each type of keratoplasty when determining which type of transplant may be most appropriate. A comprehensive literature search of glaucoma in the setting of corneal transplantation was performed and serves as the basis for this review. Preexisting glaucoma and aphakia are notable risk factors. Patients that are candidates for deep anterior lamellar keratoplasty may benefit from reduced rates of post-keratoplasty glaucoma. Although glaucoma also complicates eyes with Descemet stripping endothelial keratoplasty, the severity is less and the intraocular pressure is more easily controlled when compared to penetrating keratoplasty. Endothelial keratoplasty creates unique perioperative issues mostly related to management of anterior chamber air bubbles.

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.

Glaucoma in modified osteo-odonto-keratoprosthesis eyes: role of additional stage 1A and Ahmed glaucoma drainage device-technique and timing

PURPOSE

To report the technique, timing, and outcomes of the Ahmed glaucoma drainage device in eyes with the modified osteo-odonto-keratoprosthesis (MOOKP) and the role of an additional stage 1A to the Rome-Vienna protocol.

DESIGN

Retrospective interventional case series.

METHODS

Case records of 22 eyes of 20 patients with high intraocular pressure at various stages of the MOOKP procedure performed in 85 eyes of 82 patients were studied. Stage 1A, which includes total iridodialysis, intracapsular cataract extraction, and anterior vitrectomy, was done in all eyes as the primary stage.

RESULTS

Seventeen Ahmed glaucoma drainage devices were implanted in 15 eyes of 14 patients (chemical injury in 9 [10 eyes] and Stevens-Johnson syndrome in 5 patients). Implantation was performed during and after stage 1A in 2 and 7 eyes, respectively, after stage 1B+1C in 1 eye, and after stage 2 in 6 eyes. Eleven of 15 eyes (73.3%) remained stable with adequate control of intraocular pressure over a mean follow-up period of 33.68 months (1-90 months). Complications related to the drainage device were hypotony in 1 eye and vitreous block of the tube in 1 eye.

CONCLUSION

It is ideal to place the Ahmed glaucoma drainage device prior to the mucosal graft when the anatomy of the ocular surface is least altered with best outcomes. The technique of placement of the drainage device during the various stages of the MOOKP procedure has been described. The intraocular pressure stabilized in three quarters of the eyes with pre-existing glaucoma.