Short-term outcome of Boston Type 1 keratoprosthesis for bilateral limbal stem cell deficiency

Biologicals and Biomaterials for Corneal Regeneration and Vision Restoration in Limbal Stem Cell Deficiency

The mammalian cornea is decorated with stem cells bestowed with the life-long task of renewing the epithelium, provided they remain healthy, functional, and in sufficient numbers. If not, a debilitating disease known as limbal stem cell deficiency (LSCD) can develop causing blindness. Decades after the first stem cell (SC) therapy is devised to treat this condition, patients continue to suffer unacceptable failures. During this time, improvements to therapeutics have included identifying better markers to isolate robust SC populations and nurturing them on crudely modified biological or biomaterial scaffolds including human amniotic membrane, fibrin, and contact lenses, prior to their delivery. Researchers are now gathering information about the biomolecular and biomechanical properties of the corneal SC niche to decipher what biological and/or synthetic materials can be incorporated into these carriers. Advances in biomedical engineering including electrospinning and 3D bioprinting with surface functionalization and micropatterning, and self-assembly models, have generated a wealth of biocompatible, biodegradable, integrating scaffolds to choose from, some of which are being tested for their SC delivery capacity in the hope of improving clinical outcomes for patients with LSCD.

Eye Involvement and Management in Inherited Epidermolysis Bullosa

Inherited epidermolysis bullosa (EB) is a group of genetic rare diseases associated with skin fragility, which leads to the formation of blisters, erosions, and scars on the skin and mucous membranes. Epidermolysis bullosa includes four main types and some several clinical subtypes including EB simplex, junctional EB, dystrophic EB, and Kindler's EB. Ocular involvement ranged from 51 to 68% in EB and can cause irreversible damages if not properly managed. Corneal erosions are the most common finding among series, including our cohort. We review here clinical and pathological features of ocular involvement in EB and the main keys for management, with a focus on recent innovative therapies.

Acute and Chronic Management of Ocular Disease in Stevens Johnson Syndrome/Toxic Epidermal Necrolysis in the USA

Stevens Johnson syndrome and toxic epidermal necrolysis are on a spectrum of a severe, immune-mediated, mucocutaneous disease. Ocular involvement occurs in the vast majority of cases and severe involvement can lead to corneal blindness. Treatment in the acute phase is imperative in mitigating the severity of chronic disease. Advances in acute treatment such as amniotic membrane transplantation have shown to significantly reduce the severity of chronic disease. However, AMT is not a panacea and severe chronic ocular disease can and does still occur even with aggressive acute treatment. Management of chronic disease is equally critical as timely intervention can prevent worsening of disease and preserve vision. This mini-review describes the acute and chronic findings in SJS/TEN and discusses medical and surgical management strategies.

Outcomes of the Boston type 1 and the Aurolab keratoprosthesis in eyes with limbal stem cell deficiency

PURPOSE

To analyse the outcomes of keratoprosthesis in eyes with limbal stem cell deficiency (LSCD) and to compare the outcomes in two different keratoprosthesis devices.

METHODS

This was a single-centre retrospective comparative case series which included 81 eyes of patients with severe bilateral corneal blindness secondary to LSCD. The patients underwent either Boston type 1 keratoprosthesis (Boston Kpro, n=44) or Aurolab keratoprosthesis (AuroKpro, n=37) implantation. The primary outcome measures of anatomical retention and functional recovery of 20/200 or better visual acuity at yearly time points until 5 years of follow-up were compared between the two groups.

RESULTS

The most common indication overall was chemical injury (64.2%). Anatomical retention rates were similar in the Boston Kpro (30/44, 68.2%) and AuroKpro (23/37, 62.2%) groups (p=0.89). Kaplan-Meier survival rates at 5 years of follow-up were greater for the Boston Kpro group with respect to both anatomical retention (58.51%±9% vs 43.8±12%; p=0.23) as well as functional recovery (42.61%±8% vs 35.03±10%; p=0.9); these differences were not statistically significant. Overall, the most common complication was new-onset glaucoma (59%; 48/81). The difference in incidence rate of this complication was not statistically significant among the two groups (p=0.09).

CONCLUSION

Keratoprosthesis is an effective treatment option for patients with corneal blindness secondary to LSCD. In a setting where LSCD is a common cause of corneal blindness, the AuroKpro, when available can be considered an alternative to the Boston Kpro to achieve anatomical and functional success in patients who otherwise would not have access to this device.

The Aurolab Keratoprosthesis (KPro) versus the Boston Type I Kpro: 5-year Clinical Outcomes in 134 Cases of Bilateral Corneal Blindness

PURPOSE

To compare the clinical outcomes of Boston Type I keratoprosthesis (Boston Kpro) with its low-cost version, the Aurolab Kpro (auroKPro).

DESIGN

Retrospective comparative case series.

METHODS

This study included 134 eyes of 130 patients with severe bilateral corneal blindness but with wet ocular surfaces. The patients underwent either Boston Kpro (n = 78) or auroKPro (n = 56) implantation based on the device availability and patient's affordability. The primary outcome measurements were anatomical retention (defined as absence of device extrusion, exchange, or explantation) and functional recovery of 20/200 or better visual acuity at yearly time points until 5-years of follow-up.

RESULTS

Limbal stem cell deficiency was the most common indication (60.5%) for surgery, followed by multiple failed grafts (35%). Both groups were comparable at baseline with respect to indications for surgery and associated ocular co-morbidities (P > 0.05). The overall anatomical retention rates were similar in the Boston Kpro (55 of 78, 70.5%) and auroKPro (35 of 56, 62.5%) groups (P = 0.11). Kaplan-Meier survival rates at 5 years of follow-up were greater for the Boston Kpro with respect to both anatomical retention (63 ± 6% vs. 43.4 ± 10%, respectively; P = 0.057) and functional recovery (42.4 ± 6% vs. 32.2 ± 7%, respectively; P = 0.345), but these differences were not statistically significant. Complications such as intraoperative device breakage (7%) and postoperative extrusions (12.5%) were significantly more common with the auroKPro (P = 0.023).

CONCLUSIONS

Both the auroKPro and the Boston Kpro are effective treatment options for patients with severe bilateral corneal blindness. The auroKPro can be considered an alternative to the Boston Kpro when affordability or availability of the Boston Kpro is a limiting factor.

Diagnostic criteria for limbal stem cell deficiency before surgical intervention-A systematic literature review and analysis

An accurate diagnosis of limbal stem cell deficiency (LSCD) is the premise of an appropriate treatment; however, there is no consensus about the diagnostic criteria for LSCD. We performed a systematic literature search of the peer-reviewed articles on PubMed, Medline, and Ovid to investigate how LSCD was diagnosed before surgical intervention. The methods used to diagnose LSCD included clinical presentation, impression cytology, and in vivo confocal microscopy. Among 131 eligible studies (4054 eyes), 26 studies (459 eyes, 11.3%) did not mention the diagnostic criteria. In the remaining 105 studies, the diagnosis of LSCD was made on the basis of clinical examination alone in 2398 eyes (62.9%), and additional diagnostic tests were used in 1047 (25.8%) eyes. Impression cytology was used in 981 eyes (24.2%), in vivo confocal microscopy was used in 29 eyes (0.7%), and both impression cytology and in vivo confocal microscopy were used in 37 eyes (0.9%). Our findings suggest that only a small portion of patients underwent a diagnostic test to confirm the diagnosis of LSCD. Treating physicians should be aware of the limitations of clinical examination in diagnosing LSCD and perform a diagnostic test whenever possible before surgical intervention.

LVP keratoprosthesis: anatomical and functional outcomes in bilateral end-stage corneal blindness

PURPOSE

To describe the anatomical and functional outcomes of the novel LVP keratoprosthesis (Kpro), developed as an alternative to the modified osteo-odonto keratoprosthesis (MOOKP), in eyes with end-stage corneal blindness where conventional corneal surgeries are contraindicated.

METHODS

This prospective case series included 58 eyes of 56 patients (12 children and 44 adults) with severe bilateral keratopathy and completely dry, dermalised ocular surfaces who underwent unilateral LVP Kpro implantation from 2012 to 2016. In this two-stage procedure, an ocular surface labial mucous membrane grafting was performed, followed for 3 months by the implantation of the device under the engrafted mucosal flap. The primary outcome measures were anatomical retention rate and improvement in best corrected visual acuity (BCVA). The secondary outcome measure was rate of occurrence of complications.

RESULTS

Mean postoperative follow-up was 2.5±1.1 years. Kaplan-Meier survival analysis showed an anatomical retention rate of 90.8%±3.9% at 1 year, 80%±5.7% at 2 years and 76.6%±6.5% at 3-5 years. The survival rates were comparable in children and adults (91% vs 72% at 5 years, p=0.258). About 61.5% of eyes maintained 20/400 or better vision and median BCVA improved from perception of light to 20/70 at 1 year postoperatively (p<0.0001). Complications like retroprosthetic membrane formation, glaucoma, vitritis, endophthalmitis and panophthalmitis occurred in 43%, 26%, 22%, 12% and 3% of the eyes, respectively.

CONCLUSION

The LVP Kpro is an effective procedure for the treatment of end-stage corneal blindness in completely dry eyes. The LVP Kpro can be particularly useful in situations where the MOOKP is contraindicated or difficult to perform.

Boston keratoprosthesis type 1 for limbal stem cell deficiency after severe chemical corneal injury: A systematic review

PURPOSE

To systematically review the published literature on outcomes of Boston keratoprosthesis type 1 for the treatment of limbal stem cell deficiency secondary to severe chemical corneal injury.

METHODS

Literature searches were conducted in MEDLINE (Ovid), Embase, Web of Science, and the Cochrane Central Register. The main outcome measures assessed were the proportion of eyes with best-corrected visual acuity (BCVA) ≥ 20/200 and the proportion retaining their original keratoprosthesis, both at the last recorded visit.

RESULTS

We identified 9 reports in which outcomes of Boston keratoprosthesis type I implantation after severe chemical injury could be determined, encompassing a total of 106 eyes of 100 patients. There were no randomized controlled studies. The median pre-operative BCVA was hand motion. Vision improved to ≥20/200 in 99/106 (93.4%) eyes after implantation. With a mean follow-up of 24.99 ± 14 months, 68/106 (64.1%) eyes retained BCVA ≥ 20/200 at the last examination. Therefore, 68/99 (68.7%) of those who improved to > 20/200 maintained at least this acuity. The originally implanted device was retained in 88/99 (88.9%) recipients for whom retention was reported. The mean time to failure was 22.36 ± 17.2 months. Glaucomatous optic neuropathy was the most common cause for BCVA <20/200 in eyes that retained the keratoprosthesis (18/27, 66.7%)..

CONCLUSIONS

Implantation of a Boston keratoprosthesis type I in eyes with corneal blindness after severe chemical ocular injury leads to functional vision in the majority of recipients. Evidence was limited by variability in outcome reporting and an absence of controlled studies..

Existence of Normal Limbal Epithelium in Eyes With Clinical Signs of Total Limbal Stem Cell Deficiency

PURPOSE

To report the presence of normal limbal epithelium detected by in vivo confocal laser scanning microscopy (IVCM) in 3 cases of clinically diagnosed total limbal stem cell deficiency (LSCD).

METHODS

This is a retrospective case report consisting of 3 patients who were diagnosed with total LSCD based on clinical examination and/or impression cytology. Clinical data including ocular history, presentation, slit-lamp examination, IVCM, and impression cytology were reviewed.

RESULTS

The etiology was chemical burn in 3 cases. One patient had 2 failed penetrating keratoplasties. Another had allogeneic keratolimbal transplantation, but the graft failed 1 year after surgery. The third patient had failed amniotic membrane transplantation. These 3 patients presented with signs of total LSCD including the absence of normal Vogt palisades, complete superficial vascularization of the peripheral cornea, nonhealing epithelial defects, and corneal scarring. Impression cytology was performed in 2 cases to confirm the presence of goblet cells. However, each patient still had distinct areas of corneal and/or limbal epithelial cells detected by IVCM.

CONCLUSIONS

Residual normal limbal epithelial cells could be present in eyes with clinical features of total LSCD. IVCM seems to be a more accurate method to evaluate the degree of LSCD.

Diagnostic criteria for limbal stem cell deficiency-a systematic literature review

The diagnosis of limbal stem cell deficiency (LSCD) is often based on clinical manifestations with or without the use of tests to demonstrate the presence of goblet cells or of specific epithelial markers on the corneolimbal surface. This systematic review looks at the various diagnostic methods used in the diagnosis of LSCD in published interventional studies. The design is a systematic literature review. We did a systematic search on MEDLINE and PUBMED for articles published in English between January 1, 2003, and December 31, 2013. We collected data on diagnostic methods used to diagnose LSCD (clinical findings, impression cytology, immunohistochemistry for various epithelial markers, or in vivo confocal microscopy). Forty-six studies (mostly retrospective/interventional case series) met the inclusion criteria. All of the studies used clinical features as evidence of LSCD: discomfort, impaired vision, irregular epithelium, unstable tear film, persistent epithelial defects, scarring, fibrovascular pannus, neovascularization, keratinization, calcification, and opacification of the cornea. Eighteen studies (39.1%) used an additional test for the diagnosis; 17 studies (37.0%) used impression cytology for goblet cells, 4 studies (8.7%) used immunohistochemistry for epithelial markers, and 2 studies (4.3%) use in vivo confocal microscopy. The diagnosis of LSCD was made in most cases on clinical grounds alone. In some studies, diagnostic tests were used, but these varied considerably from study to study. Comparison of effectiveness of various interventions requires standardized diagnostic methods. Consensus on the diagnostic criteria for LSCD is essential and needs to be reached by the interested care providers.

Acute and Chronic Ophthalmic Involvement in Stevens-Johnson Syndrome/Toxic Epidermal Necrolysis - A Comprehensive Review and Guide to Therapy. II. Ophthalmic Disease

Our purpose is to comprehensively review the state of the art with regard to Stevens- Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), with particular attention to improving the management of associated ocular surface complications. SJS and TEN are two ends of a spectrum of immune-mediated disease, characterized in the acute phase by a febrile illness followed by skin and mucous membrane necrosis and detachment. Part I of this review focused on the systemic aspects of SJS/TEN and was published in the January 2016 issue of this journal. The purpose of Part II is to summarize the ocular manifestations and their management through all phases of SJS/TEN, from acute to chronic. We hope this effort will assist ophthalmologists in their management of SJS/TEN, so that patients with this complex and debilitating disease receive the best possible care and experience the most optimal outcomes in their vision and quality of life.

Mucosal complications of modified osteo-odonto keratoprosthesis in chronic Stevens-Johnson syndrome

PURPOSE

To describe clinical outcomes of complications afflicting the autologous oral mucous membrane graft after modified osteo-odonto keratoprosthesis surgery in chronic Stevens-Johnson syndrome (SJS).

DESIGN

Prospective case series.

METHODS

This study included 30 eyes of 30 patients with SJS-induced dry keratinized ocular surfaces; the patients underwent various stages of this procedure between August 2009 and February 2012. Mucosal complications were classified as either necrosis or overgrowth. Mucosal necrosis was managed according to a predesigned algorithm based on timing (pre- and postimplantation) and location (central or peripheral) of necrosis. Cases with mucosal overgrowth underwent mucosal debulking and trimming.

RESULTS

Mucosal necrosis developed in 15 (50%) eyes and overgrowth in 4 (13.3%) eyes. Preimplantation necrosis (n = 7) was initially managed conservatively, but 2 eyes required free labial-mucous membrane grafting for persistent corneal exposure. Free labial-mucous membrane grafting was performed in all cases of postimplantation necrosis (n = 10), but 8 eyes required additional tarsal pedicle flaps (n = 6, for peripheral necrosis) or through-the-lid revisions (n = 2, for central necrosis). Debulking and trimming effectively managed all cases of mucosal overgrowth, but 3 eyes required repeat procedures. At 24.1 ± 6.5 months postimplantation, the keratoprosthesis was retained in all eyes, and the probability of maintaining 20/60 or better vision was similar in eyes with or without mucosal necrosis (86 ± 8.8% vs 80 ± 10.3%).

CONCLUSIONS

Mucosal complications, especially necrosis, occurred commonly following modified osteo-odonto keratoprosthesis surgery in dry keratinized post-SJS eyes. The algorithm-based management approach described in this study was successful in treating these complications, retaining the prosthesis and preserving useful vision.