Amit Todani

Retention Of The Boston Keratoprosthesis Type 1: Multicenter Study Results

OBJECTIVE To report the retention rate of the Boston keratoprosthesis type 1 and to identify risk factors for keratoprosthesis loss. DESIGN Cohort study. PARTICIPANTS A total of 300 eyes of 300 patients who underwent implantation of the Boston keratoprosthesis type I device between January 2003 and July 2008 by 19 surgeons at 18 medical centers. METHODS Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site. MAIN OUTCOME MEASURES Keratoprosthesis retention. RESULTS A total cumulative number of 422 life-years of device implantation are included in this analysis. The average duration of follow-up was 17.1 ± 14.8 months, with a range of 1 week to >6.1 years. Ninety-three percent of the 300 Boston keratoprosthesis implants were retained at their last follow-up, corresponding to a retention time of 396 patient-years or 1.42 years/keratoprosthesis. The probability of retention after 1 year and 2 years was 94% and 89%, respectively. During the study period, 21 (7%) eyes failed to retain the device; the reasons for keratoprosthesis loss include sterile keratolysis (9), fungal infections (8), dense retroprosthetic membranes (3), and bacterial endophthalmitis (1). Multivariate analysis demonstrated 3 independent risk factors for keratoprosthesis loss: autoimmune cause (hazard ratio [HR], 11.94; 95% confidence interval [CI], 3.31-43.11), ocular surface exposure requiring a concomitant tarsorrhaphy (HR, 3.43; 95% CI, 1.05-11.22), and number of prior failed penetrating keratoplasties (HR, 1.64; 95% CI, 1.18-2.28). CONCLUSIONS The Boston keratoprosthesis type 1 seems to be a viable option for eyes that are not candidates for penetrating keratoplasty (PK). Ocular surface disease due to an autoimmune cause demonstrated the lowest retention rate. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Risk factors for the development of retroprosthetic membranes with Boston Keratoprosthesis type 1: multicenter study results

OBJECTIVE The purpose of this study was to identify possible risk factors for retroprosthetic membrane (RPM) development in a large, multicenter cohort of patients receiving a Boston type 1 keratoprosthesis. DESIGN Cohort study. PARTICIPANTS The final analysis included 265 eyes of 265 patients who underwent implantation of a Boston keratoprosthesis type I device between January 2003 and July 2008 by 1 of 19 surgeons at 18 medical centers. METHODS Forms reporting preoperative, intraoperative, and postoperative parameters were prospectively collected and subsequently analyzed at a central data collection site. MAIN OUTCOME MEASURES The primary outcome was the presence or absence of an RPM during the follow-up period. RESULTS The average age of patients was 63.3±19.1 years, 48.5% of the patients were female, and 52.5% of procedures were performed on the right eye. The mean follow-up time was 17.8±14.9 months. The majority (85.4%; n = 222) had undergone an average of 2.2±1.2 (range, 1-8) penetrating keratoplasties before keratoprosthesis implantation, and 38 eyes (14.6%) received a primary keratoprosthesis. The overall RPM formation rate was 31.7% (n = 84). The most significant risk factor for RPM development was infectious keratitis (as a surgical indication for keratoprosthesis surgery itself), resulting in a rate of RPM formation of 70.6%. As an independent risk factor, the hazard ratio (HR) of RPM development in these eyes was 3.20 (95% confidence interval, 1.66-6.17). Aniridia was also an independent risk factor for RPM development (HR, 3.13; 95% confidence interval, 1.10-8.89). CONCLUSIONS Formation of RPM is a common complication of keratoprosthesis surgery, occurring in approximately one-third of cases. Eyes at the highest risk of RPM development are those receiving corneal replacement for infectious keratitis and aniridia.

Intraocular Pressure Measurement by Radio Wave Telemetry

PURPOSE To determine the biocompatibility of a new wireless intraocular pressure (IOP) transducer (WIT) in rabbit eyes and to correlate its measurements with other pressure-measuring devices. METHODS The WIT is a ring-shaped intraocular device that allows wireless IOP measurements through radiofrequency. It was implanted into six eyes of New Zealand White rabbits after extracapsular lens extraction. A sham rabbit eye with no transducer implanted was used as a control. The animals were observed and examined by microscopy at various intervals up to 25 months after surgery. IOP was measured at various intervals by pneumotonometry, tonometry, WIT, and manometry. The data from the various devices were compared and analyzed for reproducibility. Two eyes were enucleated at 5.5 and 20 months after implantation and analyzed by histology. RESULTS The WIT appears to be well tolerated in the rabbit eye, with no evidence of significant inflammation or scar formation by microscopic in vivo examination. Histology did not reveal intraocular inflammation or membrane formation. Repeated IOP measurements with pneumotonometry, tonometry, and the WIT resulted in SDs of 2.70 mm Hg, 3.35 mm Hg, and 0.81 mm Hg, respectively. The concordance between the WIT and direct manometry measurements was high. A downward drift in IOP measured by the WIT was noted in three rabbits, necessitating recalibration. CONCLUSIONS The WIT is well tolerated by the rabbit eye. Its measurements are reproducible and in close concordance with manometry. A downward IOP drift warrants further investigation.

Cost-Effectiveness of the Boston Keratoprosthesis

PURPOSE To conduct a cost-utility analysis and determine the cost-effectiveness of the Boston Keratoprosthesis (Boston Kpro). DESIGN Retrospective cohort study. METHODS setting: The Massachusetts Eye and Ear Infirmary corneal service. patients: Inclusion required a minimum 2-year follow-up. Patients with autoimmune diseases and chemical burns were excluded. Eighty-two patients were included with various indications for surgery. intervention: The keratoprosthesis is a collar button-shaped polymethylmethacrylate (PMMA) device consisting of 2 curved plates sandwiched around a corneal donor (allo)graft. The device is assembled intraoperatively and sutured to a patients eye after removing the diseased cornea. MAIN OUTCOME MEASURES Average cost-effectiveness of the keratoprosthesis was determined by cost-utility analysis, using expected-value calculations and time-tradeoff utilities. The comparative effectiveness, or gain in quality-adjusted life years (QALYs), was also sought. Cost-effectiveness was compared to recently published data on penetrating keratoplasty (PK). RESULTS A total discounted incremental QALY gain for the Boston Kpro of 0.763 correlated with a conferred QALY gain of 20.3% for the average patient. The average cost-effectiveness of the keratoprosthesis was

Biocompatibility and biofilm inhibition of N,N-hexyl,methyl-polyethylenimine bonded to Boston Keratoprosthesis materials

16 140 per QALY. CONCLUSIONS Comparable to corneal transplantation, with a cost-effectiveness between

Pterygium: current concepts in pathogenesis and treatment.

12 000 and

Laser in situ keratomileusis buttonhole: Classification and management algorithm

16 000 per QALY, the keratoprosthesis can be considered highly cost-effective.

Prevention of visually debilitating deposits on soft contact lenses in keratoprosthesis patients.

The biocompatibility and antibacterial properties of N,N-hexyl,methyl-polyethylenimine (HMPEI) covalently attached to the Boston Keratoprosthesis (B-KPro) materials was evaluated. By means of confocal and electron microscopies, we observed that HMPEI-derivatized materials exert an inhibitory effect on biofilm formation by Staphylococcus aureus clinical isolates, as compared to the parent poly(methyl methacrylate) (PMMA) and titanium. There was no additional corneal epithelial cell cytotoxicity of HMPEI-coated PMMA compared to that of control PMMA in tissue cultures in vitro. Likewise, no toxicity or adverse reactivity was detected with HMPEI-derivatized PMMA or titanium compared to those of the control materials after intrastromal or anterior chamber implantation in rabbits in vivo.

Anterior chamber gas bubble emergence pattern during femtosecond LASIK-flap creation

A pterygium is a commonly occurring ocular surface disorder, named for its resemblance to an insect wing. The multitude of treatment options currently advocated and practiced in different parts of the world is characterized by the absence of a universal approach. However, some of the traditional methods of treatment, such as bare sclera technique have fallen out of favor because of high recurrence rates (19.4% to 75%). Other adjunctive therapies, such as b-irradiation and postoperative topical mitomycin-C, have also become less popular because of cost, operational issues or occurrence of serious complications such as scleral necrosis and intraocular infections. In recent years, new modalities of treatment have included conjunctival autografts (CAs), amniotic membrane transplantation (AMT) and fibrin glue instead of sutures. The purpose of this article is to present a summary of the currently advocated treatment options from a review of the recent literature.

Late-onset epithelial ingrowth after laser in situ keratomileusis

PURPOSE: To report the classification, management, and visual outcomes after laser in situ keratomileusis (LASIK) flap buttonhole caused by a microkeratome cut. SETTING: Private practice, Boston, Massachusetts, USA. METHODS: This retrospective observational case series comprised 15 patients with an intraoperative LASIK flap buttonhole or near buttonhole. In all cases, the flap was left in place or repositioned without excimer laser treatment. Buttonholes were classified by stage, and a treatment algorithm based on the stage was devised to determine the timing and type of intervention. The uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA), and complications associated with the laser vision correction surgery were reported. RESULTS: Postoperative follow‐up ranged from 1 week to 23 months. All 9 patients who were retreated had a postoperative UCVA of 20/25 or better. No retreated patient lost BSCVA. Before retreatment, the median UCVA was 20/80 (range 20/40−1 to counting fingers), the median BSCVA was 20/20−2 (range 20/15−1 to 20/70), and the spherical equivalent (SE) refractive errors ranged from −1.00 to −6.62 diopters (D). After retreatment, the median UCVA was 20/20−2 (range 20/15−1 to 20/25−1), the median BSCVA was 20/20 (range 20/15 to 20/20−3), and the SE refractive errors ranged from +0.50 to −0.75 D. Complications after laser correction treatment included overcorrection in 3 patients and corneal haze in 2 patients. CONCLUSIONS: Classification of buttonholes was helpful in guiding treatment. Good UCVA and BSCVA were achieved by following a simple treatment algorithm based on surface ablation.