Influence of primary diagnosis and complications on visual outcome in patients receiving a Boston type 1 keratoprosthesis.

PURPOSE: To analyse how primary diagnosis and complications affect the evolution of post-operative visual acuity (VA). METHODS: We performed retrospective chart analysis on 59 eyes in 57 patients with various diagnoses, most of which were non-standard indications for Boston type 1 keratoprosthesis (Kpro) implantation. The follow-up period was at least 3 months. Patients were classified based on the evolution of post-operative VA: group A demonstrated stable VA improvement, group B lost VA improvement and group C no significant VA improvement. RESULTS: We assigned 46% of our cases to group A with stable VA improvement, 32% to group B with lost VA improvement, and 22% to group C with no VA improvement. The number of graft failures before Kpro implantation did not influence VA outcome. Except for the relatively good VA outcome in chemical burn and radiation injury patients, there seems to be no association between primary diagnosis and positive or negative VA outcome. Only 9% of patients with posterior segment complications and 20% with infections and associated pathologies were assigned to group A. CONCLUSION: Most cases (78%) showed improvement in VA after Boston type 1 Kpro (groups A and B). Posterior segment complications and infections mostly resulted in persistent loss of vision. These complications should be prevented and carefully treated.

Anatomical survival and visual prognosis of Boston type I keratoprosthesis in challenging cases.

PURPOSE: To describe the outcome of patients with Boston type 1 keratoprosthesis, with regard to anatomical and visual success. METHODS: Retrospective case series of patients who underwent Boston type I keratoprosthesis surgery at the Centro de Oftalmología Barraquer in Barcelona and at the University Eye Clinic in Salzburg between May 2006 and December 2011. Sixty-seven eyes were included. Anatomical success, visual acuity, and complication rate were evaluated and correlated with the initial diagnosis. RESULTS: The mean age of patients was 54 years; 62 % were male and 38 % were female. Eleven patients underwent Type I Boston Kpro implantation as a primary procedure, while the other 52 patients had previous graft failure. The most frequent diagnoses were autoimmune diseases (16 eyes), severe chemical or thermal burn (12 eyes), leukoma post-infectious keratitis (seven eyes) and bullous keratopathy (six eyes). The mean follow-up time was 26 months. Retention of the prosthesis was achieved in 95 % at 1 year and 78 % at 4.5 years. Two eyes suffered extrusion of the KPro, six underwent successful exchange of the prosthesis either due to infection, necrosis or extrusion, three KPro's had to be explantated, and two eyes ended up in enucleation due to panophthalmitis. The outcome of the autoimmune cases was similar to the group with "other diagnoses" and better than those with chemical/thermal burn. The most frequent complication was development of a retroprosthetic membrane in 21 eyes (34 %). Visual acuity (LogMAR) in the chemical/thermal burn group was 2.30 preoperatively, 0.69 at 1 year, 0.52 at 2 years and 0.39 at 3 years; in the autoimmune group visual acuity was 2.3 preoperatively, 0.65 at 1 year, 0.15 at 2 years, and 1.5 at 3 years. CONCLUSIONS: Boston type 1 keratoprosthesis is a viable option for patients with repeated graft failure, even for those with challenging diagnoses such as ocular burns and autoimmune syndromes.

Bilateral reading performance of 4 multifocal intraocular lens models and a monofocal intraocular lens under bright lighting conditions.

PURPOSE: To compare changes in reading performance parameters after implantation of 4 multifocal intraocular lens (IOL) models and a monofocal IOL. SETTING: Department of Ophthalmology, Paracelsus Medical University, Salzburg, Austria. DESIGN: Prospective randomized controlled clinical trial. METHODS: Patients with bilateral cataract without additional ocular pathology were scheduled for bilateral implantation of Acri.Smart 48S monofocal, Acrysof Restor SN6AD3 apodized multifocal, AT LISA 366D diffractive multifocal, Tecnis ZMA00 diffractive multifocal, or Rezoom refractive multifocal IOLs. Bilateral corrected and uncorrected reading acuity, reading distance, mean and maximum reading speeds, and smallest log-scaled print size of a Radner reading chart were evaluated under bright lighting conditions (500 lux) using the Salzburg Reading Desk. Pupil size was not measured throughout the trial. The minimum follow-up was 12 months. RESULTS: The diffractive multifocal groups had significantly better uncorrected reading acuity and uncorrected smallest print size than the monofocal and refractive multifocal groups 1, 6, and 12 months postoperatively. The diffractive IOL groups had comparable uncorrected reading distance of approximately 32 cm, which was larger in the monofocal group (38.9 ± 8.4 cm) and refractive multifocal group (37.1 ± 7.3 cm) at the last visit. Patients with diffractive IOLs could read print sizes of approximately 0.74 to 0.87 mm, which was much better than in the monofocal and refractive multifocal groups. The diffractive AT LISA IOL provided the best reading speed values (mean and maximum, corrected and uncorrected). CONCLUSION: Multifocal IOLs with a diffractive component provided good reading performance that was significantly better than that obtained with a refractive multifocal or monofocal IOL. FINANCIAL DISCLOSURE: Drs. Grabner and Dexl were patent owners of the Salzburg Reading Desk technology (now owned by SRD-Vision, LLC). No other author has a financial or proprietary interest in any material or method mentioned.

Correction of myopic astigmatism with a foldable iris-claw toric phakic intraocular lens: short-term follow-up.

PURPOSE: To evaluate the efficacy, predictability, stability, and complications after implantation of a foldable iris-fixated toric phakic intraocular lens (pIOL) to correct myopic astigmatism. SETTING: University Eye Clinic, Paracelsus Medical University, Salzburg, Austria. DESIGN: Retrospective nonrandomized observational case series. METHODS: The study assessed eyes having implantation of an Artiflex toric pIOL with spherical power ranging from -1.0 to -13.5 diopters (D) and additional cylinder from -1.0 to -5.0 D, both in 0.5 D increments. The main parameters were uncorrected (UDVA) and corrected (CDVA) distance visual acuities, manifest refraction stability, slitlamp biomicroscopy, tonometry, and central endothelial cell count (ECC). RESULTS: The study enrolled 42 eyes of 24 patients with a mean age of 35 years (range 18 to 52 years), a mean spherical equivalent of -7.52 D ± 2.22 (SD) (range -2.63 to -13.0 D), and a mean preoperative cylinder of -1.82 ± 0.96 D (range -1.0 to -5.0 D). Six months postoperatively, the UDVA (Snellen lines) was 1.0 or better in 38 eyes (90%). The CDVA improved by 1 line in 22 eyes (52%) and by 2 lines in 2 eyes (5%); no eye lost lines. All eyes were within ±0.50 of the target refraction (spherical equivalent); the mean refractive astigmatism was -0.18 ± 0.30 D. Refraction was stable from 1 day postoperatively. A slight ECC loss (-0.72%) occurred at 6 months. There were no serious complications. CONCLUSION: After a short-time follow-up, toric pIOL implantation was effective, predictable, stable, and safe for the correction of myopic astigmatism.

Long-term follow-up of a supradescemetic keratoprosthesis in rabbits: an immunofluorescence study.

OBJECTIVE: To evaluate the long-term clinical and immunohistological outcome of two different non-penetrating keratoprosthesis (KPro) implanted in non-injured rabbit corneas. MATERIALS AND METHODS: Three rabbits underwent implantation of a pHEMA-MMA(34) synthetic cornea in the supradescemetic space, and PMMA synthetic corneas in the supradescemetic space and within the central stroma. Animals were followed for at least 24 months before euthanasia. Periodic evaluation was performed with slit-lamp examination and photography. At the end of the follow-up, histological examination including hematoxylin eosin staining and immunocharacterization against collagen IV, alpha smooth muscle actin (α-SMA) and macrophages was performed. RESULTS: The pHEMA-MMA(34) implant was not extruded, and remained transparent until the end of follow-up. This material did not induce any cell infiltration, corneal scarring or tissue remodeling in the surrounding stroma as shown by immunofluorescence. In contrast, synthetic corneas made of PMMA-induced myofibroblast differentiation, stromal remodeling and macrophage infiltration. This reaction was even more significant in the rabbit with the PMMA implant within the corneal stroma. CONCLUSION: pHEMA-MMA(34) was clinically biocompatible, and did not induce any inflammatory reaction or scarring when implanted in the supradescemetic space. This material showed more promising biocompatibility results than for PMMA, whether implanted within the central cornea stroma or in the supradescemetic space.

Corneal stroma regeneration in felines after supradescemetic keratoprosthesis implantation.

PURPOSE: To show corneal regeneration in 3 cats that underwent lamellar keratectomy (90%) depth during supradescemetic keratoprosthetic implantation. METHODS: Three 2-year-old cats that underwent spontaneous keratoprosthesis extrusion between 15 and 150 days after implanting a supradescemetic prosthesis into their right eyes were studied. Corneal structures and stroma thickness were evaluated by slit-lamp photographs, pachymetry, and confocal microscopy. Regenerated corneal epithelial cells, stroma matrix, and keratocyte morphology were studied with histology and transmission electron microscopy. Epithelial and stromal cell immunocharacterization was performed. RESULTS: Corneas progressively regained normal thickness and improved clarity within 40 to 60 days. Slit-lamp photographs and pachymetry showed gains in stromal thickness until 600 microm or more. In vivo confocal microscopy showed the restoration of normal epithelium and stroma in all cats. Corneal nerves were seen in the regenerated stroma of 2 cats. Immunostaining showed absent alpha-smooth muscle actin (SMA) expression and a keratin K3-expressing epithelium. Electron microscopy showed regeneration of normal epithelium with a well-formed basement membrane, organized corneal lamellae, and the presence of normal keratocytes. CONCLUSION: Felines are capable of regenerating corneal structures including epithelium and reinnervated stroma matrix after deep lamellar keratectomy. The use of feline models in corneal keratoprosthesis is therefore questionable.

Ex vivo evaluation of Tono-Pen and pneumotonometry in cat eyes.

PURPOSE: To evaluate the validity and intraobserver reliability of intraocular pressure (IOP) measurements with both pneumotonometry and the Tono-Pen in a closed ex vivo system in cat eyes. METHODS: IOP was increased step by step in 5 enucleated cat eyes, while taking IOP measurements with the Tono-Pen and pneumotonometry. The outcomes were compared to readings of a digital manometer simultaneously measuring the actual pressure in the anterior chamber. RESULTS: Pneumotonometry overestimated IOP below 15 mm Hg and underestimated pressures above 20 mm Hg. Tono-Pen tonometry considerably underestimated IOP over the whole spectrum in all of the eyes tested. The pneumotonometer was identified as the more valid and reliable instrument for cat eyes. CONCLUSION: Both tonometers are clinically useful tools to assess IOP for glaucoma studies using a cat animal model. However, one has to consider underestimation of IOP in the upper ranges. A correction formula can be used to calculate the actual IOP.

Trabecular meshwork alteration and intraocular pressure change following pulsed near-infrared laser trabeculoplasty in cats.

BACKGROUND AND OBJECTIVE: To comparatively assess the safety and variation in intraocular pressure (IOP) of two pulsed near-infrared lasers (titanium:sapphire and alexandrite) for laser trabeculoplasty versus conventional blue-green argon laser trabeculoplasty in an animal model. MATERIALS AND METHODS: The left eyes of 15 healthy cats received a 180 degree laser trabeculoplasty treatment: 5 with a titanium:sapphire laser, 5 with an alexandrite laser, and 5 with an argon laser. Preoperatively and postoperatively, all animals underwent tonometry, gonioscopy, and slit-lamp examination. The cats were observed up to 12 weeks. Scanning electron microscopy and histologic examination were performed to evaluate potential alterations in the trabecular meshwork structure. RESULTS: IOP at 1 hour, 1 day, and 1 week following treatment was remarkably lower, irrespective of the laser source used. Following treatment with both near-infrared lasers, gonioscopy showed depigmentation underneath the area of the treated trabecular meshwork and histologic evaluation showed a decrease in pigment density. On scanning electron microscopy, damage to the trabecular meshwork structure could not be detected after treatment with near-infrared lasers. CONCLUSIONS: Near-infrared laser trabeculoplasty was found to be effective to temporarily lower IOP in cats. The lasers selectively altered pigment-containing cells, avoiding structural damage of the trabecular meshwork anatomy.

Biocompatibility of a nonpenetrating synthetic cornea in vascularized rabbit corneas.

PURPOSE: This study was designed to assess feasibility and biocompatibility of a lamellar, nonperforating supraDescemetic Synthetic Cornea (sDSC) implanted in rabbit eyes after a corneal injury. METHODS: Corneal vascularization and scarring was induced in the right eye of 15 rabbits by application of 1-heptanol and complete surgical removal of the limbus. An sDSC (7-mm diameter, 450-microm-thick optical zone, 100-microm-thick outer flange) was implanted after 45 +/- 5 days. The keratoprostheses were implanted with their central optic part positioned on a completely exposed Descemet's membrane (DM) while the outer flange was located in deep stroma. Three different materials were tested: hydrophobic PMMA (n = 5) and hydrophilic HEMA-MMA (n = 5) and HEMA-NVP (n = 5) with a water content of 34% and 75%, respectively. The corneal surface was covered with a conjunctiva-Tenon flap. Central flap trephination was performed after 63 +/- 7 days. DM vascularization and scarring was assessed and graded after flap opening and weekly thereafter. RESULTS: In all 15 consecutive cases implantation could be completed successfully without perforation of DM. Repair of the conjunctival flap had to be performed in five rabbits. Four months postoperatively, the flaps were opened. Four of five corneas (80%) with a PMMA implant and three of five (60%) with a HEMA-NVP75 implant had retained their original transparency. The others had developed significant neovascularization in the Descemet-sDSC optic interface. All corneas (100%) that received an sDSC made of HEMA-MMA34 displayed a completely clear DM without any vessels or scarring. DM was found firmly attached to the posterior surface of the optic. CONCLUSION: Implantation of a nonperforating synthetic cornea on top of an exposed DM is feasible. HEMA-MMA34 showed the most promising results. Because opening of the anterior chamber is not required, a lamellar supraDescemetic Synthetic Cornea would theoretically reduce some of the risks attributed to penetrating keratoprostheses.

Biological response to a supraDescemetic synthetic cornea in rabbits.

OBJECTIVE: To evaluate the biocompatibility of a novel nonpenetrating keratoprosthesis (supraDescemetic synthetic cornea) in a rabbit model. METHODS: Seven rabbits received a supraDescemetic synthetic cornea (7-mm diameter, 350-microm-thick optical zone, 100-microm-thick peripheral flange) in their healthy right eyes. A surgical technique was developed that allowed implantation of the device on top of the bare Descemet membrane. Three rabbits received a supraDescemetic synthetic cornea made of hydroxyethyl methacrylate-methyl methacrylate(26), 1 received a hydroxyethyl methacrylate-N-vinyl pyrrolidone(75) mesoplant, and 3 were implanted with devices made of polymethyl methacrylate. All rabbits were euthanized after 8 weeks; the eyes were enucleated and examined by conventional histological and immunohistochemical evaluations. RESULTS: All eyes became quiet within several days. The Descemet membrane remained transparent during the observation period. Indirect ophthalmoscopy performed through the prosthesis allowed accurate examination of the posterior pole. Histological evaluation of the implanted corneas displayed no signs of an acute or chronic inflammatory reaction to the supraDescemetic synthetic cornea in 5 eyes; a few inflammatory cells were detected in the corneas of 2 rabbits. The interface between the Descemet membrane and the mesoplant displayed ingrowth of very thin (<10-microm) tissues colonized by keratocytes in 3 of the 7 corneas. CONCLUSIONS: This study validates the biocompatibility of this new type of nonpenetrating keratoprosthesis. Because opening of the anterior chamber is not required with the supraDescemetic synthetic cornea, the risk for intraocular infection is minimal, and the implantation procedure is less traumatic compared with a penetrating device.

Anterior chamber angle biometry with ultrasound biomicroscopy after diode laser thermal keratoplasty.

PURPOSE: To evaluate the effect of diode laser thermal keratoplasty (DTK) on the geometry of the anterior chamber angle with ultrasound biomicroscopy (UBM). SETTING: Department of Ophthalmology and Optometry, Paracelsus Private Medical University, Salzburg, Austria. METHODS: In 9 eyes, a Rodenstock DTK (ProLaser Medical Systems) was used to correct hyperopia (n = 6) or hyperopic astigmatism (n = 3). Hyperopia was treated with a single- or double-ring pattern and hyperopic astigmatism, with additional spots in each of the flat half meridians. Ultrasound biomicroscopy measurements of the chamber angle were obtained preoperatively and 3 months postoperatively using a Humphrey UBM 840 system with a 50 MHz transducer. Quantitative measurements were performed at 3-, 6-, 9-, and 12-o'clock positions using a standardized method. RESULTS: No statistically significant differences between the preoperative and postoperative chamber angle measurements were detected. CONCLUSIONS: The results of the UMB measurements were surprising given the flattening of the corneal periphery found by computerized topography, a finding that suggests narrowing of the chamber angle. Shortening of the corneal tissue may result in centripetal traction that affects the trabecular meshwork and results in a relative opening of the chamber angle structures.

Correction of astigmatism with short arc-length intrastromal corneal ring segments: preliminary results.

OBJECTIVE: To evaluate the refractive effect of 130 degrees short arc length intrastromal corneal ring segments (ICRS) designed to correct myopia concurrent with astigmatism. DESIGN: Prospective, nonrandomized, comparative (self-controlled) trial. PARTICIPANTS: Ten eyes of 6 patients from one surgical center with manifest refraction spherical equivalent between -1.00 and -6.00 diopters (D), manifest cylinder correction between 1.00 and 6.00 D, and best spectacle-corrected visual acuity of 20/20 or better. INTERVENTION: The patients were assigned to receive 1 of 6 ICRS thicknesses, ranging from 0.25 to 0.50 mm by 0.05 mm increments, with an arc length of 130 degrees. MAIN OUTCOME MEASURES: Vector analysis of astigmatic correction. Efficacy was assessed by uncorrected visual acuity and by deviation of postoperative spherical and cylindrical refractive error from predicted correction. Safety was assessed by maintenance or loss of preoperative best spectacle-corrected visual acuity. Measurements were made before surgery and after surgery at days 1 and 7 and months 1, 2, 3, and 6. RESULTS: At 6 months, uncorrected visual acuity was 20/20 or better in 80% of eyes (8/10) and 20/40 or better in all eyes. Eight of 10 eyes (80%) were within +/-0.25 D of plano spherical equivalent manifest refraction. There was no loss of best spectacle-corrected visual acuity, and 6 of 10 eyes (60%) gained a line. Reduction of keratometric cylinder by ICRS thickness was statistically significant (P = 0.039). CONCLUSIONS: Preliminary results of visual and refractive performance after correction of compound myopic astigmatism using short arc length ICRS are promising.

Evaluation of bone reduction in osteo-odontokeratoprosthesis (OOKP) by three-dimensional computed tomography.

PURPOSE: To study the stability and preservation of the osteodental lamina in osteo-odontokeratoprosthesis (OOKP) according to Strampelli with spiral computed tomography (CT). METHODS: Computed tomography of the orbit was performed in nine patients after successful OOKP surgery. Indications for surgery included ocular pemphigoid (three patients), Lyell's syndrome (two patients), graft versus host disease (one patient), and severe chemical burns (three patients). In four eyes, the osteodental lamina was covered with a buccal mucosa graft; in five eyes, a "transpalpebral" approach with the placement of the optical cylinder through the patient's own lid skin was used. The mean time from surgery to examination was 4 years. The age of the patients ranged from 32 to 75 years (mean, 52). Spiral CT in the transaxial plane was performed, followed by three-dimensional (3D) surface reconstruction of the OOKP. The dimensions of the osteodental lamina were measured and compared with measurements taken at the time of surgery. RESULTS: A minor reduction of the lamina, mainly in the anterior and inferior part, could be found in all the patients without loss of stability and integrity of the lamina cylinder complex in seven patients. One patient showed complete resorption of the inferior half of the osteodental lamina, and another patient demonstrated "moth-eaten" dissolution of dentine and bone tissue. No correlation between the degree of reduction in the dimensions and patient age, diagnosis, or length of follow-up could be found. CONCLUSION: Osteo-odontokeratoprosthesis shows good results in patients with corneal blindness not amenable to keratoplasty. Nevertheless, the surgeon must be aware of eventual signs of dissolution of the osteodental lamina, making close follow-up mandatory. Because ultrasound biomicroscopy cannot be used in these cases, spiral CT with 3D reconstruction seems to be a good diagnostic alternative.

Histopathology of human corneas after amniotic membrane and limbal stem cell transplantation for severe chemical burn.

PURPOSE: To describe the histopathologic changes in the cornea following amniotic membrane transplantation (AMT) combined with limbal transplantation. METHODS: Four eyes with complete limbal stem cell deficiency after severe chemical burn underwent AMT with either a living-related conjunctival limbal allograft (lr-CLAL) (three eyes) or a conjunctival limbal autograft (CLAU) (one eye) for ocular surface reconstruction. Penetrating keratoplasty was performed several months after the initial procedure for further visual rehabilitation. Mean follow up time was 20 months. Light and transmission electron microscopy (TEM) and indirect immunofluorescence microscopy of the excised corneal buttons were performed. RESULTS: All specimens displayed a multilayered epithelium without conjunctival goblet cells over the entire corneal surface. Basal epithelial cells demonstrated a firm connection to the remnants of the transplanted amniotic membrane (AM), which at some places appeared to be in a state of "modification" or "remodeling" in the collagen layers. The basement membrane zone displayed a positive staining when using antibodies against collagen IV and VII, integrin alpha6 and beta4, laminin 5, and bullous pemphigoid antigen 2. Remnants of the AM in the specimen showed staining of collagen IV, which was found also in cross-sections of cryopreserved AM. The recipients Bowman's membranes that were only partially present after the initial trauma were significantly disturbed. CONCLUSION: Within the time frame studied, the transplanted AM apparently survives and integrates into the host tissue being modified or remodeled by recipient cells. AMT in combination with a CLAU or lr-CLAL is a useful technique in promoting a rapid and stable reepithelialization of a corneal surface following severe chemical or thermal damage.

Histopathologic findings in explanted osteo-odontokeratoprosthesis.

PURPOSE: To report the histologic findings in three explanted osteo-odontokeratoprosthesis (OOKP) laminae. METHODS: The osteodental lamina of patient 1 with linear IgA bullous dermatosis had to be explanted 15 months after OOKP surgery because of permanent leakage after the resorption of the inferior half of the bone/dentin complex. Patient 2 underwent surgery because of corneal blindness caused by ocular pemphigoid. The remnants of the osteodental lamina were removed after a spontaneous loss of the optic cylinder 30 months after surgery. Patient 3 showed decentration of the optic cylinder 14 years after OOKP surgery was performed because of severe bilateral chemical burn. After intraoperative detachment of the optical cylinder from the broken lamina, the keratoprosthesis had to be completely removed. All specimens were fixed, decalcified using electrolysis, sectioned, and stained with hematoxylin and eosin. RESULTS: All three laminae showed some degree of transformation and resorption of dentin and bone tissue. An inflammatory reaction could be observed in the laminae of patient 1 and 2. Downgrowth of keratinizing squamous epithelium and a reduction of bone tissue and dentin was found in patient 1. Most of the osteodental lamina of patient 2 had been replaced by connective tissue. No signs of acute or chronic inflammation could be found in patient 3. The optical cylinder was surrounded by a thin layer of connective tissue that was enclosed by a layer of woven bone. Dentine was found in just one half of the specimen, adjacent to a partly preserved alveolar-dental ligament. CONCLUSION: No conclusive explanation for the dissolution of the osteodental lamina in some of the patients can be offered at this time, although a few different mechanisms such as epithelial downgrowth and/or localized inflammation seem to play a pivotal role. Conversely, the preservation of the alveolar-dental ligament seems to be essential for the maintenance of the integrity of the OOKP.