Microbiota Evaluation of Patients With a Boston Type I Keratoprosthesis Treated With Topical 0.5% Moxifloxacin and 5% Povidone–Iodine

Topical Antibiotic Therapy in the Ocular Environment: The Benefits of Using Moxifloxacin Eyedrops

Moxifloxacin is a fourth-generation fluoroquinolone antibiotic available for ophthalmic use. It inhibits two enzymes involved in bacterial DNA synthesis, covering Gram-positive and Gram-negative pathogens. This spectrum allows for the formulation of self-preserving bottle solutions, while its interesting pharmacological profile is distinguished by efficacy at low tissue concentrations and by an infrequent dose regimen due to its long duration on ocular tissues. This enhances patient compliance, promoting its use in children. The human eye hosts several microorganisms; this collection is called the ocular microbiota, which protects the ocular surface, assuring homeostasis. When choosing an antibiotic, it is appropriate to consider its influence on microbiota. A short dose regimen is preferred to minimize the impact of the drug. Moxifloxacin eyedrops represent an effective and safe tool to manage and prevent ocular infections. As healthcare providers face the complexity of the ocular microbiota and microbial resistance daily, the informed use of moxifloxacin is necessary to preserve its efficacy in the future. In this regard, it is well known that moxifloxacin has a lower capacity to induce resistance (an optimal WPC and MPC) compared to other quinolones, but much still needs to be explored regarding the impact that fluoroquinolones could have on the ocular microbiota.

Candida Colonization on the Surface of Contact Lenses in Long-Term Wearers and Boston Type 1 Keratoprosthesis Patients Presenting as White Mulberry-Shaped Deposits

PURPOSE

To report Candida colonies on the surface of the contact lens in long-term contact lens wearers and patients with Boston type 1 keratoprosthesis (KPro I).

METHODS

A retrospective study was performed based on analyzing cultures from bandage contact lenses with small whitish mulberry-shaped deposits on their surface.

RESULTS

Eight samples (from seven patients) were positive for Candida. Seven of the eight were positive for Candida parapsilosis.

CONCLUSIONS

The whitish deposits on contact lenses are often Candida colonies that colonize the surface but do not cause an active infection in the eye. C. parapsilosis is well-known for colonizing prosthetic devices. We underline the importance of including Candida species in the differential diagnosis of lens deposits, especially in susceptible patients such as keratoprosthesis carriers.

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.

Infectious Keratitis After Boston Type 1 Keratoprosthesis Implantation

PURPOSE

To identify the incidence, risk factors, and outcomes of infectious keratitis after Boston type 1 keratoprosthesis (kpro) implantation.

METHODS

Retrospective case series of kpro procedures at the Stein Eye Institute and the Centre Hospitalier de l'Université de Montréal between May 1, 2004, and December 31, 2018. Data were collected regarding ocular history, operative details, postoperative management, microbiologic profile, treatment, and outcomes. Log-rank test and Cox proportional hazard ratio (HR) were used to evaluate for an association between risk factors and outcomes.

RESULTS

A total of 349 kpro procedures were performed in 295 eyes of 268 patients. Fifty-seven cases of presumed infectious keratitis were identified after 53 procedures (15.2%) in 50 eyes (16.9%) of 49 patients (18.3%). The incidences of culture-positive bacterial and fungal keratitis were 0.014 and 0.004 per eye-year, respectively. Persistent corneal epithelial defect formation (P < 0.001) and cicatricial disease (HR: 1.98, 95% confidence interval, 1.02-3.83) were associated with a significantly higher incidence of infectious keratitis. For the 53 cases with a known outcome, medical therapy achieved resolution of infection in 34 cases (64.2%), whereas kpro explantation was required in 19 cases (35.8%). Infectious keratitis was associated with an increased risk for kpro explantation (HR: 3.09, 95% confidence interval, 1.92-4.79).

CONCLUSIONS

Infectious keratitis develops in approximately 17% of eyes after kpro implantation, with a higher rate of culture-positive bacterial than fungal keratitis. The observed rate of microbial keratitis suggests the need for additional topical antimicrobial prophylaxis in eyes at higher risk, such as those with preexisting cicatricial disease or postoperative persistent corneal epithelial defect formation.

The Search for Antifungal Prophylaxis After Artificial Corneal Surgery-An In Vitro Study

PURPOSE

To evaluate the antifungal properties of topical antibiotics (already being used successfully to prevent bacterial endophthalmitis) and some promising antiseptics for antifungal prophylaxis in the setting of artificial corneal implantation.

METHODS

Several commonly used antibiotics for antimicrobial prophylaxis after artificial corneal implantation, in addition to antiseptics [benzalkonium chloride (BAK), povidone-iodine (PI), and some ionic liquids (ILs)], were tested in vitro against Candida albicans, Fusarium solani, and Aspergillus fumigatus. The time-kill activity was determined. Toxicity was assayed in vitro on human corneal epithelial cultures using trypan blue. Adhesion and tissue invasion experiments were also carried out on porcine corneas and commonly used contact lenses, with or without gamma irradiation, and by analysis with fluorescence microscopy.

RESULTS

Polymyxin B (PMB)/trimethoprim/BAK (Polytrim), PMB alone, gatifloxacin with BAK (Zymaxid), and same-concentration BAK alone exhibited antifungal activity in vitro. Moxifloxacin (MOX) or gatifloxacin without BAK-as well as trimethoprim, vancomycin, and chloramphenicol-had no effect. 1% PI and ILs had the highest efficacy/toxicity ratios (>1), and Polytrim was species dependent. Subfungicidal concentrations of Polytrim reduced adhesion of C. albicans to Kontur contact lenses. Gamma-irradiated corneas showed enhanced resistance to fungal invasion.

CONCLUSIONS

Of antibiotic preparations already in use for bacterial prophylaxis after KPro surgery, Polytrim is a commonly used antibiotic with antifungal effects mediated by both PMB and BAK and may be sufficient for prophylaxis. PI as a 1% solution seems to be promising as a long-term antifungal agent. Choline-undecanoate IL is effective and virtually nontoxic and warrants further development.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Infectious Keratitis After Ocular Surface Stem Cell Transplantation

PURPOSE

To describe the rate, clinical/microbiological characteristics, and outcomes of infectious keratitis in eyes with limbal stem cell deficiency after ocular surface stem cell transplantation (OSST).

METHODS

In this retrospective chart review of 278 eyes that underwent OSST between January 2006 and December 2016, eyes treated for previous infectious keratitis (bacterial, fungal, or viral) were included. Demographics, risk factors, course, microbiological characteristics, and outcomes were assessed.

RESULTS

A total of 52 eyes (18.7%) of 48 patients (28 men and 20 women) developed 75 episodes (culture-proven or presumed) of infectious keratitis (range 1-4 episodes) with mean follow-up of 5.3 ± 3.6 years after OSST. The most common limbal stem cell deficiency etiologies included chemical/thermal (27 episodes), Stevens-Johnson syndrome (19 episodes), aniridia (8 episodes), and mucous membrane pemphigoid (8 episodes). There were 44 (58.7%) bacterial keratitis episodes, 24 (32%) fungal keratitis episodes, and 7 (9.3%) HSV keratitis episodes. Gram-positive bacteria (79%) and Candida species (73%) were the most common bacterial and fungal pathogens. Before infection, 33% had an epithelial defect, 69% had a bandage contact lens, 91% were on systemic immunosuppression, and 25% recently had undergone ocular surgery (<3 months). Although 75% resolved with antimicrobial treatment, 25% required a therapeutic keratoplasty (TPK; 2 cases needed multiple TPK).

CONCLUSIONS

Despite successful OSST surgery, infectious keratitis is relatively common, and aggressive medical/surgical therapy is warranted. Prophylactic topical antibiotics and a cicatrizing conjunctivitis diagnosis may account for the high proportion of fungal keratitis in this population.

Keratoprosthesis prophylaxis: is it time for a paradigm shift?

The Boston Type I Keratoprosthesis has been improving in both design and safety since its inception. Due to particular features inherent in the Boston Type I Keratoprosthesis eye and certain aspects of the ocular surface, special attention is required to maintain these implanted devices. There is currently a prominent role for keratoprosthesis prophylaxis; it is designed to prevent infectious complications like keratitis and endophthalmitis. This standard-of-care therapy has anecdotally been shown to improve outcomes; however, it has not been examined in the setting of controlled clinical trials. Moreover, concerns remain with the chronic utilization of topical antibiotics in that they may engender antibiotic resistance and select for opportunistic populations to establish a foothold on the ocular surface. We believe and introduce the idea that there is merit in exploring other compounds besides antibiotics for prophylaxis such as antiseptics like povidone-iodine. Specifically developed formulations of povidone-iodine may prove useful in both improving keratoprosthesis safety and simultaneously mitigating concerns regarding antibiotic resistance.

Boston Type I Keratoprosthesis: Antibacterial Resistance and Microbiota Evaluation of Soft Contact Lenses

PURPOSE

To evaluate microbiota colonizing soft contact lenses (CL) in eyes with Boston type I keratoprosthesis (BKPro), and determine the prevalence of resistance to fourth-generation fluoroquinolone (FQ).

DESIGN

Prospective, observational study.

SUBJECTS

Patients with BKPro using CL as routine who were in postoperative follow-up in the Department of Ophthalmology of the Federal University of Sao Paulo, and volunteered to participate in the study. All patients were under a prophylactic scheme of topical 0.5% moxifloxacin 3 times a day and topical 5% povidone-iodine (PI) at the time of CL exchange.

METHODS

Patients on scheduled replacement scheme of CL had their lenses removed and sent for microbiological analysis. Standard culture methods were used for microorganism identification and susceptibility to different antibiotics was tested. Main outcome measure was prevalence of resistance to fourth-generation FQ.

RESULTS

Among the 19 eyes, 12 eyes (63%) had at least 1 positive bacterial culture. The most prevalent isolates were Staphylococcus epidermidis and other coagulase-negative staphylococci. Actinomyces viscosus was isolated in 1 CL. Fungal cultures were all negative. Of the 12 eyes with culture bacterial growth, resistance to fourth-generation FQ (0.5% moxifloxacin) was identified in 6 different eyes (50%). None presented infectious complications.

CONCLUSIONS

FQ-resistant bacteria were isolated in some patients. Although our prophylactic antibiotic regimen has been efficient in preventing bacterial infection, this analysis demonstrated that prophylaxis with PI and low FQ dose might increase resistance to antibiotics. Investigations in this field may help to outline future changes of prophylactic guidelines and therapeutic strategies.

Fungal keratitis and endophthalmitis after implantation of type 1 keratoprosthesis

A 70-year-old patient who underwent uneventful primary implantation of Auro K Pro (a Type I Boston Keratoprosthesis-based device), developed infiltrates in the deep stroma of the carrier corneal graft and exudates on the optic stem of the keratoprosthesis assembly, 6 weeks postoperatively, which subsequently progressed to endophthalmitis. Vitreous tap was positive for a panfungal polymerase chain reaction, although corneal scrapings for both Gram stain and KOH wet mount yielded negative results. Aggressive management with systemic, topical, intravitreal, and intrastromal antifungal agents resulted in an initial resolution, but residual inflammatory vitreous membranes persisted. The patient was then lost to follow-up and presented 3 months later with a total, inoperable retinal detachment. Fungal infections after keratoprosthesis implantation remain a significant concern and may be associated with poor outcomes in the developing countries due to interplay of environmental and socioeconomic factors. Management protocols may need to be modified in accordance with the prevailing conditions in these regions.

The use of povidone-iodine in ophthalmology

PURPOSE OF REVIEW

Povidone-iodine (PVI) is a disinfectant and antiseptic agent used for preoperative preparation of the skin and mucous membranes, as well as for the treatment of contaminated wounds. Currently regimens for prophylaxis against postsurgical endophthalmitis are being modified, including a total withdrawal of antibiotics in intravitreal injections. The aim of this study was to evaluate the use of PVI in ophthalmology.

RECENT FINDINGS

As a result of its broad spectrum of microbicidal activity, PVI is routinely used in ophthalmic surgery. However, various protocols are applied worldwide and within different procedures. Additional indications include prophylaxis against ophthalmia neonatorum, acute conjunctivitis, adenoviral conjunctivitis, bacterial keratitis or corneal ulcer, endophthalmitis, giant fornix syndrome, and antimicrobial prophylaxis in patients with Boston type I keratoprosthesis.

SUMMARY

Despite the introduction of new antiseptics in surgery, PVI is still the preeminent antiseptic measure in ophthalmology. Its use is economically reasonable. There have been no reports of resistance to PVI or anaphylaxis with topical ophthalmic use. Furthermore, it does not induce resistance or cross-grztance to antibiotics. With these advantages the range of indications for topical use of antibiotics might decrease, with PVI as the sole perioperative antiseptic measure. Additional studies are required to assess the optimal timing, concentration and exposure time within different ophthalmic procedures.

Boston Type 1 Keratoprosthesis for Gelatinous Drop-Like Corneal Dystrophy

PURPOSE

To report the outcomes of Boston type 1 keratoprosthesis in the management of advanced gelatinous drop-like corneal dystrophy (GDLD).

METHODS

A retrospective, noncomparative, interventional case series was conducted at Ramathibodi Hospital, Bangkok, Thailand. Four eyes of three siblings with molecularly and histologically confirmed GDLD from a Thai family underwent an uneventful Boston type 1 keratoprosthesis implantation for visual rehabilitation. Clinical data were obtained from a review of the medical records. Visual acuity, device retention, and postoperative complications were the main outcome measures. The follow-up ranged from 8 to 96 months.

RESULTS

One eye received keratoprosthesis surgery as a primary penetrating procedure. The other three eyes had the surgery as a secondary procedure after graft failure. Best-corrected visual acuity was favorably improved from counting fingers to 20/25 in two eyes, from hand movement to 20/20 in one eye, and from hand movement to counting fingers at 2 feet in one eye caused by severe amblyopia. The improved vision was maintained for 8 months to 6.2 years after surgery. Postoperative complications included disease recurrence in the donor graft (N = 3), manageable retroprosthetic membrane (N = 3), intraocular pressure elevation responded to antiglaucoma drugs (N = 2), and Pseudomonas keratitis with severe corneal melting requiring device removal (N = 1). All of our patients failed to have a comfortably well-fitting contact lens after surgery.

CONCLUSIONS

Boston type 1 keratoprosthesis could be considered as a reasonable option in the management of advanced GDLD. However, patients remain at risk for sight-threatening postoperative complications as long as the keratoprosthesis is retained. The use of Boston keratoprosthesis implantation needed to be individualized on a case-by-case basis.

Streptococcus agalactiae Endophthalmitis in Boston Keratoprosthesis in a Patient with Steven-Johnson Syndrome

A 25-year-old Syrian male with a previous episode of Stevens-Johnson syndrome with bilateral corneal cicatrization previously underwent surgery for Type 1 Boston Keratoprosthesis (K-Pro). Sixteen months after the K-Pro surgery, the patient presented with decreased vision to hand motion and microbial keratitis of the graft around the K-Pro with purulent discharge. Corneal scrapings were nonrevealing. B-scan in 3 days showed increased debris in the vitreous cavity and thickened retinochoroidal layer. Intravitreal tap and injections of vancomycin and ceftazidime were performed. The vitreous culture revealed β-hemolytic Streptococcus agalactiae; fungal cultures were negative. Repeat B-scan 3 days later demonstrated decreased vitreous opacity, and the patient felt more comfortable and was without pain. His visual acuity improved to 20/70, ocular findings have been stable for 9 months, and the patient continues to be monitored.

Microbial Keratitis and Endophthalmitis After the Boston Type 1 Keratoprosthesis

PURPOSE

To determine the incidence, ocular surface disease associations, microbiological profile, and clinical course of postoperative infections after implantation of the Boston type 1 keratoprosthesis (KPro-1).

METHODS

A retrospective chart review was conducted of all cases of the KPro-1 performed at a tertiary eye care center between January 1, 2008, and December 31, 2014.

RESULTS

Seventy-five KPro-1 procedures were included in the analysis. Postoperative infections occurred in 13 eyes (17.3%) with an incidence of 0.064 cases per eye-year. The Kaplan-Meier probability of an infection-free graft was 0.96, 0.90, 0.88, 0.87, and 0.86 at years 1 through 5, respectively. The rate of infections was greater in eyes with ocular surface disease (26.3% vs. 8.1%, P = 0.06), especially in those with a history of chemical or thermal injury or herpes zoster keratopathy (P = 0.001). There were 8 cases (10.7%) of microbial keratitis due to either fungi (5 cases) or bacteria (3 cases). There were 7 cases (9.3%) of endophthalmitis due to bacteria (5 cases) or intraocular extension of fungal keratitis (2 cases). The incidence of microbial keratitis and endophthalmitis was 0.034 and 0.03 cases per eye-year, respectively. Therapeutic management of the infected eyes required graft and device removal in 7 eyes (53.8%). After completion of microbiologic treatment, 7 eyes (53.8%) had lost more than 2 lines of the best-corrected preinfection visual acuity, including 5 eyes with endophthalmitis that had hand motion vision or worse.

CONCLUSIONS

Postoperative infections are a serious issue that compromises device retention and visual outcomes after keratoprosthesis implantation.

Fungal Infections After Boston Type 1 Keratoprosthesis Implantation: Literature Review and In Vitro Antifungal Activity of Hypochlorous Acid

PURPOSE

To review the current literature describing cases of fungal keratitis and endophthalmitis after Boston keratoprosthesis (KPro) implantation and to characterize the antifungal activity of 0.01% hypochlorous acid against medically relevant fungi.

METHODS

A literature review of fungal keratitis or endophthalmitis in KPro patients from January 2001 to April 2015, and an in vitro time kill assay characterizing the fungicidal activity of 0.01% hypochlorous acid against fungi causing ocular infections.

RESULTS

Fifteen publications, predominantly retrospective case series, were identified. Infection rates after KPro implantation ranged from 0.009 to 0.02 fungal infections per patient-year of follow-up. The largest single-surgeon series reported an incidence of 2.4% for fungal endophthalmitis during a 10-year period. Causative organisms included both yeasts and molds. Outcomes were favorable if infections were caught early and treated appropriately; less favorable outcomes were reported in developing countries where fungal species are endemic and resources are limited. 0.01% hypochlorous acid is rapidly fungicidal, reducing the number of viable yeast cells or mold conidia by at least 99.99% within 60 seconds. The antifungal activity extended to all molds (Acremonium kiliense, Aspergillus flavus, Aspergillus fumigatus, Fusarium solani, and Mucor indicus) and yeast species (Candida albicans and Candida parapsilosis) tested.

CONCLUSIONS

Fungal infections remain a lifelong concern in patients after KPro implantation. There is a growing need for a standard antifungal prophylaxis regimen, especially in the developing world. The rapid broad-spectrum in vitro fungicidal activity of 0.01% hypochlorous acid against all fungi tested makes it an attractive candidate as an antifungal prophylaxis in KPro patients.

Prophylactic Vancomycin Drops Reduce the Severity of Early Bacterial Keratitis in Keratoprosthesis

BACKGROUND

Artificial cornea transplantation, keratoprosthesis, improves vision for patients at high risk of failure with human cadaveric cornea. However, post-operative infection can cause visual loss and implant extrusion in 3.2-17% of eyes. Long-term vancomycin drops are recommended following keratoprosthesis to prevent bacterial keratitis. Evidence, though, in support of this practice is poor. We investigated whether prophylactic vancomycin drops prevented bacterial keratitis in an animal keratoprosthesis model.

METHODOLOGY

Twenty-three rabbits were assigned either to a prophylactic group (n = 13) that received vancomycin 1.4% drops 5 times/day from keratoprosthesis implantation to sacrifice, or a non-prophylactic group (n = 10) that received no drops. All rabbits had Staphylococcus aureus inoculation into the cornea at 7-12 days post-implantation and were sacrificed at predetermined time-points. Prophylactic and non-prophylactic groups were compared with slit-lamp photography (SLP), anterior segment optical coherence tomography (AS-OCT), and histology, immunohistochemistry and bacterial quantification of excised corneas. Corneal vancomycin pharmacokinetics were studied in 8 additional rabbits.

RESULTS

On day 1 post-inoculation, the median SLP score and mean±SEM AS-OCT corneal thickness (CT) were greater in the non-prophylactic than the prophylactic group (11 vs. 1, p = 0.049 and 486.9±61.2 vs. 327.4±37.1 μm, p = 0.029 respectively). On days 2 and 4, SLP scores and CT were not significantly different. Immunohistochemistry showed a greater CD11b+ve/non-CD11b+ve cell ratio in the non-prophylactic group (1.45 vs. 0.71) on day 2. Bacterial counts were not significantly different between the two groups. Corneal vancomycin concentration (2.835±0.383 μg/ml) exceeded minimum inhibitory concentration (MIC) for Staphylococcus aureus only after 16 days of vancomycin drops. Two of 3 rabbits still developed infection despite bacterial inoculation after 16 days of prophylactic drops.

CONCLUSIONS

Prophylactic vancomycin drops provided short-term benefit, but did not prevent infection. Achieving MIC in the cornea was not sufficient to prevent Staphylococcus aureus keratitis. Patients should continue to be counselled regarding the risk of infection following keratoprosthesis.

Current Concepts in the Management of Unique Post-keratoplasty Infections

As corneal transplantation has evolved, the spectrum of post-surgical infection has changed and often presents a diagnostic and therapeutic challenge. Lamellar techniques hold the potential of improved outcomes and decreased post-operative complications, however, they create a lamellar interface, which is a potential space for sequestration of infectious organisms. In addition, while keratoprosthesis offers vision to patients who are poor candidates for traditional keratoplasty, infectious complications can be severe and sight threatening. Although antimicrobials remain the mainstay of treatment, definitive management often requires surgical intervention.

Medium-term outcomes of boston type 1 keratoprosthesis implantation in Bangkok, Thailand

PURPOSE

The aim of this study was to investigate the medium-term outcomes after Boston type 1 keratoprosthesis surgery in patients with poor prognosis for standard keratoplasty.

METHODS

A prospective study of a case series was conducted at a university-based referral center from 2006 to 2013. Forty-two eyes of 40 patients with a minimum follow-up of 4 years were recruited. The main outcome measures included best spectacle-corrected visual acuity (BSCVA), keratoprosthesis retention, and complications.

RESULTS

The mean follow-up was 64.9 ± 15.2 months (range, 48-88 months). At 1 week, 90.5% had an improvement in BSCVA by ≥2 lines compared with that in preoperative BSCVA. The best-ever vision was reached by the end of 6 months. Nevertheless, 39.5% (15/38) could not maintain the improved vision. The major etiology of visual deterioration after initial gains was glaucoma (60%). The initial keratoprosthesis retention rate was 80.9%, corresponding to a failure rate of 4 per 100 eye-years or 0.04/eye-year. Autoimmune diagnosis was the independent risk factor for keratoprosthesis failure (hazard ratio, 5.68; 95% confidence interval, 1.41-22.85; P = 0.014). The common postoperative complications were glaucoma, retroprosthetic membrane, corneal melting, infectious keratitis, and endophthalmitis.

CONCLUSIONS

Boston type 1 keratoprosthesis is an alternative for patients who are not candidates for corneal transplants. However, there was a trend toward visual loss over time most commonly because of progressive glaucoma. Therefore, appropriate patient selection, lifelong follow-up, and early aggressive treatment of complications are recommended.

Boston type 1 keratoprosthesis for chemical and thermal injury

PURPOSE

To evaluate the outcome of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed interventions for chemical and thermal injury.

METHODS

A retrospective review was performed of every eye with chemical or thermal injury that was treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications.

RESULTS

Nine eyes met the inclusion criteria, including 7 eyes with alkali burns, 1 eye with an acid burn, and 1 eye with a thermal burn. After a mean follow-up of 40.7 months (range, 29-60 months), the median best-corrected visual acuity was 20/60 (range, 20/15 to no light perception). One eye was ≥20/20, 3 eyes were ≥20/40, and 6 eyes were ≥20/70. The initial Kpro-1 prosthesis was retained in 7 (77.7%) eyes and successfully replaced in the other 2 eyes. One or more serious complications occurred in 6 (66.7%) eyes. These included 2 cases of sterile corneal ulceration with prosthesis extrusion, 2 cases of microbial keratitis (1 bacterial and 1 fungal), 2 cases of bacterial endophthalmitis, and 2 cases of retinal detachments. These complications contributed to visual outcomes of hand motions in 2 eyes and no light perception in 1 eye.

CONCLUSIONS

The Boston Kpro-1 is associated with highly satisfactory visual outcomes and prosthesis retention in most cases of severe chemical or thermal injury. Serious complications are common and may compromise the final outcome.

Boston keratoprosthesis type 1 for herpes simplex and herpes zoster keratopathy

PURPOSE

The aim of this study was to evaluate and compare the outcomes of Boston keratoprosthesis type 1 (Kpro-1) in eyes with herpes simplex virus (HSV) and herpes zoster virus (HZV) keratopathy.

METHODS

A retrospective review was performed of the medical records of every patient treated with a Boston Kpro-1 at the University of Iowa Hospitals and Clinics between January 1, 2008 and July 1, 2012. Eyes with visual loss due to HSV or HZV keratopathy were included in the statistical analysis. The main outcome measures were graft retention, postoperative complications, and visual outcome.

RESULTS

Nine eyes met the inclusion criteria, including 5 eyes in the HSV group and 4 eyes in the HZV group. The graft retention rate was 100% in the HSV group after a mean follow-up of 48.4 months, compared with 25% in the HZV group after 50.5 months (P = 0.048). There were 3 cases of microbial keratitis, including 2 eyes that also developed endophthalmitis, in the HZV group, compared with no cases in the HSV group (P = 0.048). There was significantly better best-corrected visual acuity at the most recent examination in the HSV group than in the HZV group (P = 0.019). All 5 HSV eyes had improved best-corrected visual acuity compared with preoperative acuity, whereas only 1 HZV eye experienced a similar result (P = 0.048).

CONCLUSIONS

Kpro-1 is associated with an excellent prognosis for graft retention, acceptably low prevalence of sight-threatening complications, and highly satisfactory visual improvement in eyes with HSV keratopathy, but not in eyes with HZV keratopathy.

Infectious endophthalmitis in Boston keratoprosthesis: incidence and prevention

PURPOSE

To determine the cumulative worldwide incidence of infectious endophthalmitis and associated vision loss after Boston keratoprosthesis (B-KPro) Type I/II implantation and to propose both safe and inexpensive prophylactic antibiotic regimens.

METHODS

Two retrospective methods were used to determine the incidence, visual outcomes and aetiologies of infectious endophthalmitis associated with the B-KPro divided per decade: (i) systematic review of the literature from 1990 through January 2013 and (ii) a surveillance survey sent to all surgeons who implanted B-KPros through 2010 with 1-year minimum follow-up. In addition, a single-Boston surgeon 20-year experience was examined.

RESULTS

From 1990 through 2010, there were 4729 B-KPros implanted worldwide by 209 U.S. surgeons and 159 international surgeons. The endophthalmitis cumulative mean incidence declined from 12% during its first decade of use to about 3% during its second decade in the Unites States and about 5% internationally during the second decade. There remains a large incidence range both in the United States (1-12.5%) and internationally (up to 17%). Poor compliance with daily topical antibiotics is an important risk factor. While Gram-positive organisms remained dominant, fungal infections emerged during the second decade.

CONCLUSIONS

Daily prophylactic topical antibiotics have dramatically reduced the endophthalmitis incidence. Although Gram-positive organisms are the most common aetiology, antimicrobials must be inclusive of Gram-negative organisms. Selection of prophylactic regimens should be tailored to local antibiotic susceptibility patterns, be cost-effective, and should not promote the emergence of antimicrobial resistance. An example of a broad-spectrum, low-cost prophylactic option for non-autoimmune patients includes trimethoprim/polymyxinB once daily.

Experience with Boston keratoprosthesis type 1 in the developing world

OBJECTIVE

To report the experience of the Federal University of São Paulo, Brazil, in performing Boston keratoprosthesis type 1 implantation in the developing world.

METHODS

We analyzed 30 eyes of 30 patients who underwent Boston type 1 keratoprosthesis surgery between 2008 and 2012 in a prospective interventional study. Preoperative, perioperative, and postoperative parameters were analyzed, including visual acuity (VA), keratoprosthesis stability, and postoperative complications.

RESULTS

Preoperative diagnoses were failed grafts in 16 eyes (53.33%), chemical injury in 10 eyes (33.33%) and Stevens-Johnson syndrome in 4 eyes (13.33%). Also, 16 eyes (53.33%) had preoperative glaucoma. Preoperative best corrected VA ranged from 20/400 to light perception. With an average follow-up of 32 months (range 1-55 months), postoperative vision improved to >20/200 in 24 eyes (80%). Postoperative VA was statistically improved compared with the preoperative measurement during all postoperative follow-ups (up to 36 months). During the follow-up period (32 months), retention of the initial keratoprosthesis was 93.3%. The incidence of retroprosthetic membrane was 26.66%. Progression of glaucoma occurred in 7 of 16 eyes (43%). Three patients experienced development of glaucoma after keratoprosthesis implantation. One eye experienced development of infectious keratitis, and 2 eyes had retinal detachment.

CONCLUSIONS

Performing Boston type 1 keratoprosthesis in a developing country is a viable option after multiple keratoplasty failures and conditions with a poor prognosis for keratoplasty. Our experience appears similar to major reports in the field from investigators in developed countries. Adjustments to postoperative management must be considered according to the particular location.