Josef Stoiber

One year results of European multicenter study of intrastromal corneal ring segments Part 2: Complications, visual symptoms, and patient satisfaction

Purpose: To assess intraoperative and postoperative complications, visual symptoms, and patient satisfaction after implantation of intrastromal corneal ring segments (ICRS®, KeraVision, Inc.) for the correction of myopia and to demonstrate the reversibility and adjustability of refractive corrections with this method. Setting: Twelve European investigational sites. Methods: Patients with myopia of –1.0 to –6.0 diopters (D) were assigned to receive 1 of 5 ICRS thicknesses (0.25, 0.30, 0.35, 0.40, or 0.45 mm). Complications and visual symptoms were noted, and patient satisfaction was assessed at each postoperative visit (1 and 7 days and 1, 2, 3, 6, and 12 months). Refractive data were assessed after removal or exchange of the ICRS. Results: Of 163 eyes of 110 patients enrolled, 159 eyes of 107 patients were implanted with an ICRS (52 patients had bilateral implantation). Intraoperative complications occurred in 2% of eyes (4/163 eyes in 3 patients) that were withdrawn from the study: 3 eyes had anterior surface perforations and 1 had a posterior microperforation into the anterior chamber. Most patients had no visual symptoms at 12 months; symptoms usually occurred rarely or sometimes and were mild in severity. At 12 months, good or excellent patient satisfaction was reported for 94% of eyes. Twelve ICRSs (8%) were removed, mainly because of undercorrection and induced astigmatism, and 2 were exchanged. All eyes were within ±1.00 D of the preoperative manifest refraction spherical equivalent. Conclusions: The ICRS was safe for correction of low to moderate myopia. Severe postoperative visual symptoms were rare, and patient satisfaction was high. The refractive correction was largely reversible.

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 &agr;6 and &bgr;4, 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 Bowmans 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.

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.

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.

One year results of European multicenter study of intrastromal corneal ring segments: Part 1: refractive outcomes

Purpose: To assess the efficacy, predictability, stability, and safety of correcting myopia with intrastromal corneal ring segments (ICRS®, KeraVision, Inc.). Setting: Twelve European investigational sites. Methods: Patients with myopia of –1.0 to –6.0 diopters (D) and best spectacle‐corrected visual acuity (BSCVA) of 20/20 or better (except in 3 eyes) were assigned to receive 1 of 5 ICRS thicknesses (0.25, 0.30, 0.35, 0.40, or 0.45 mm). Efficacy was assessed by postoperative uncorrected visual acuity (UCVA), predictability of refractive outcome (deviation from predicted cycloplegic refraction spherical equivalent), and stability of refractive effect (manifest refraction spherical equivalent [MRSE]). Safety was assessed by maintenance or loss of preoperative BSCVA and induced manifest refraction cylinder. Measurements were made preoperatively and 1 and 7 days and 1, 2, 3, 6, and 12 months postoperatively. Results: One hundred fifty‐nine ICRSs were implanted in the eyes of 107 patients (52 patients had bilateral implantation). Preoperatively, UCVA was worse than 20/40 in 98% of eyes (155/159); 12 months postoperatively, it was 20/20 or better in 63% of eyes (83/132) and 20/40 or better in 96% (127/132). Predicted refractive corrections for each ICRS thickness generally correlated with achieved corrections. At 12 months postoperatively, 90% of eyes (124/138) were within ±1.00 D of plano (MRSE). Two or more lines of BSCVA were lost in 6% of eyes (8/135); all 8 eyes had BSCVAs of 20/25 or better. Conclusion: The ICRS safely, effectively, and predictably reduced or eliminated low to moderate myopia. Refractive correction was stable through the 12 month follow‐up.

Recurrent keratoconus in a patient with Leber congenital amaurosis.

Purpose. Clinical history of a 17-year-old patient with Leber congenital amaurosis (LCA) with histologically proven recurrent keratoconus (KC) two years after corneal transplantation in one eye and a recurrence-like appearance with a more global contour on the other eye four years after corneal grafting is reported. The possible mechanisms for this recurrence are discussed in light of the fact that this is, to the best of our knowledge, the first penetrating keratoplasty reported in LCA. Methods. Computerized videokeratography (CVKG) and specular microscopy were performed preoperatively. The patient underwent regrafting, and the excised corneal button was examined by light microscopy and transmission electron microscopy. Results. Analysis of CVKG showed a keratoconus-like pattern on the right eye, with the left eye demonstrating the aspects usually seen in keratoglobus. Histologic examination revealed the features usually observed in progressed keratoconus. Conclusion. Recurrence of keratoconus in a graft has not yet been described after such a short time until now. A “true” recurrence of the disease is postulated; it could be caused by an “aggressive” genetic factor that also leads to the frequent KC in patients with LCA. This mechanism also could explain the high incidence and rapid progress of KC in this disease.

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.

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), Lyells 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 patients 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.

Evaluation of donor tissue with a new videokeratoscope: the Keratron Scout.

Purpose. To evaluate the percentage of corneas with an epithelial surface quality sufficient for a reliable screening of donor eyes with keratoconus and after photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) treatment for refractive errors. The usefulness of the computer-assisted, video-keratography system Keratron Scout in making this determination was evaluated. Methods. Forty eyes from 20 donors were screened within 30 minutes after enucleation and within 24 hours postmortem. At first a meticulous slit-lamp evaluation of the corneal surface and stroma was performed; thereafter eight pictures per eye were taken with the Keratron Scout, and an ultrasound pachymetry reading of the corneal center was taken. “True curvature,” algorithm-based color maps were used for analysis. Epithelium was not removed, because all corneas were suitable for transplantation. Balanced salt solution was used to keep the corneas moist. The low intraocular pressure regularly found in postmortem eyes was raised to within normal ranges by intravitreal injection. Corneas were classified according to the integrity of their epithelial surface, which influences the regularity of the topography maps. Results. The quality of the images acquired varied, depending mostly on the quality of the epithelium. Regular topography patterns were found in 15 eyes (37.5%); in 14 eyes (35%), minimal epithelial roughness or sloughing in just one quadrant of the cornea was detected. Moderate to severe epithelial irregularities or defects were found in nine eyes (22.5%). Screening for abnormal shape was possible in 90% of the tested eyes, where no changes caused by prior refractive surgery or keratoconus were apparent. Conclusion. The postmortem quality of the epithelial surface allows screening for keratoconus or refractive procedures in the majority of donor eyes. Video-keratography with the Keratron Scout seems to offer a sensitive and quick method for this purpose, thereby adding an additional safety feature to eye banking in view of the rapid development of corneal refractive surgery.

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.