Propiedades biomecánicas de la membrana limitante interna tras recibir tratamiento intravítreo con ocriplasmina.

Objetivo: Evaluar la rigidez de la membrana limitante interna (MLI) humana y evaluar los posibles cambios de las propiedades mecánicas tras administrar una inyección intravítrea de ocriplasmina para tratar la tracción vitreomacular. Métodos: Este estudio se compone de una serie de casos intervencionales y comparativos de 12 muestras de MLI extraídas mediante cirugía y obtenidas de forma consecutiva de 9 ojos de 9 pacientes después de someterse sin éxito a vitreólisis farmacológica con ocriplasmina. Durante el mismo periodo de tiempo, 16 muestras de otros 13 ojos sin tratamiento con ocriplasmina se obtuvieron mediante vitrectomía y sirvieron como controles. Todos los pacientes presentaron agujeros maculares o tracción vitreomacular y se sometieron a vitrectomía con disección de la MLI tanto con tinción con azul brillante (AB) como sin ella. Todas las muestras se analizaron con un microscopio de fuerza atómica con imágenes de las regiones de 25 × 25 µm. En todas las muestras, se analizaron tanto la parte de la retina como la del vítreo de la MLI. Resultados: La microscopia de fuerza atómica no reveló diferencias significativas en cuanto a elasticidad de las muestras de MLI extraídas de ojos con o sin tratamiento con ocriplasmina. Las áreas onduladas de la parte de la retina presentaron una mayor rigidez que la parte del vítreo de la MLI. La cartografía topográfica tanto de la parte del vítreo como de la retina de la MLI no mostró ninguna alteración aparente de la morfología en ojos tratados con ocriplasmina en comparación con los ojos no tratados. La tinción con azul brillante conllevó un aumento de la rigidez tisular. Conclusiones: Las inyecciones intravítreas de ocriplasmina no varían las propiedades biomecánicas de la MLI humana. No existen pruebas de un posible efecto enzimático que interfiera con la rigidez de esta membrana basal.

Ciliary body thickness changes after preoperative anti-inflammatory treatment in rhegmatogenous retinal detachment complicated by choroidal detachment.

BACKGROUND: The literature is scant on the state of the ciliary body, its role in the development of rhegmatogenous retinal detachment (RRD) complicated by choroidal detachment (CD), and on ciliary body changes following the treatment aimed at resolving concomitant inflammation and choroidal attachment. This study assesses the anatomical position and thickness of the ciliary body and investigates the ciliary body changes after anti-inflammatory pre-vitrectomy treatment in RRD complicated by CD. METHODS: Forty-nine patients (49 eyes) with RRD complicated by CD underwent standard ophthalmological examination (including visual acuity assessment, biomicroscopy, ophthalmoscopy, and ocular tonometry) and ultrasound biomicroscopy of the ciliary body, choroid, and retina both before and following anti-inflammatory pre-vitrectomy treatment. RESULTS: At baseline, all subject eyes had ciliary body edema and detachment extending into the choroid. Ultrasonographic ciliary features included ciliary body edema and disorganization of the supraciliary layer of the pars plana, which was evident by the presence of multiple small oblique fibers. In all subject eyes, the treatment resulted in reattachment of the choroid and the ciliary body as well as a reduction in ciliary body edema (total mean ciliary thickness reduced from 0.83 (0.09) to 0.65 (0.09) mm, with a difference of 0.18 (0.07) mm, P < 0.001). CONCLUSIONS: Preoperative anti-inflammatory treatment in RRD complicated by CD results in restoration of the anatomical position of the ciliary body and a statistically significant reduction in ciliary body edema.

Biomechanical Properties of the Internal Limiting Membrane after Intravitreal Ocriplasmin Treatment.

PURPOSE: To assess the stiffness of the human internal limiting membrane (ILM) and evaluate potential changes of mechanical properties following intravitreal ocriplasmin injection for vitreomacular traction. METHODS: This is an interventional comparative case series of 12 surgically excised ILM specimens consecutively obtained from 9 eyes of 9 patients after unsuccessful pharmacologic vitreolysis with ocriplasmin. During the same time period, 16 specimens from 13 other eyes without ocriplasmin treatment were harvested during vitrectomy and served as controls. All patients presented with macular holes or vitreomacular traction and underwent vitrectomy with ILM peeling either with or without brilliant blue (BB) staining. All specimens were analyzed using atomic force microscopy with scan regions of 25 × 25 µm. In all specimens, both the retinal side and vitreal side of the ILM were analyzed. RESULTS: Atomic force microscopy revealed no significant differences in elasticity of ILM specimens removed from eyes with or without ocriplasmin treatment. Undulated areas of the retinal side presented stiffer than the vitreal side of the ILM. Topographical mapping of both the vitreal and retinal side of the ILM showed no apparent alteration of the morphology in ocriplasmin-treated eyes compared to untreated eyes. Staining with BB resulted in an increase of tissue stiffness. CONCLUSIONS: Intravitreal injection of ocriplasmin does not change biomechanical properties of the human ILM. There is no evidence of a potential enzymatic effect of ocriplasmin interfering with the stiffness of this basement membrane.

Intravitreal ranibizumab for the treatment of choroidal neovascularizations associated with pathologic myopia: a prospective study.

PURPOSE: It was the aim of this study to determine the efficacy of intravitreal ranibizumab as treatment of choroidal neovascularizations associated with pathologic myopia. MATERIALS AND METHODS: In an uncontrolled, prospective time series cohort study, 65 eyes of 64 consecutive patients with choroidal neovascularization associated with pathologic myopia were treated with intravitreal ranibizumab and observed over 12 months. The change in best-corrected visual acuity (BCVA) at 6 and 12 months served as primary end point. Safety, central retinal thickness, neovascularization activity on fluorescein angiography and the number of ranibizumab injections were secondary end points. RESULTS: BCVA improved significantly throughout the follow-up (p = 0.001). The mean BCVA was 0.2 at baseline (SD 0.13) and 0.4 at 12 months (SD 0.21). Improvement was strongest within the first 3 months (p = 0.0001). The mean central retinal thickness showed a reduction from 313 µm (SD 82) to 243.5 µm (SD 31; p = 0.0001). CONCLUSION: Intravitreal ranibizumab offers a safe and effective treatment for choroidal neovascularizations in pathologic myopia.

High-frequency electric welding: a novel method for improved immediate chorioretinal adhesion in vitreoretinal surgery.

PURPOSE: To evaluate high-frequency electric welding (HFEW) as a novel technique for retinopexy with improved immediate chorioretinal adhesion METHODS: In a prospective, randomized, experimental study, we examined 104 eyes of 52 rabbits randomly assigned to either standard 810 nm endolaser retinopexy, alternating current 14-16 V or 18-20 V HFEW retinopexy. A full-thickness fragment of eye wall tissue containing the retinopexy was isolated 1 h, 3 days, 1 week, or 1 month respectively after the intervention, and fixed to an analytical electronic scale. A nylon suture passed through the retina was elevated by a biomechanical force elongation tester. The reduction in weight at the time of retinopexy rupture was registered as a measure for retinopexy adhesion strength. RESULTS: One hour post-exposure, adhesive strengths were significantly higher in both HFEW groups than in controls (212 ± 26.6 mg and 122 ± 16 mg vs 104 ± 10 mg; p = 0.0001 and p = 0.024 respectively) while laser retinopexy did not significantly change adhesive strength (114 ± 14.0 mg, p = 0.149). Subsequent adhesive strengths were significantly increased for all retinopexy techniques: 3 days post-op 14-16 V HFEW 224 ± 30.0 mg (p = 0.001), 18-20 V HFEW 128 ± 15.6 (p = 0.001), laser 131 ± 12.7 mg (p = 0.0007); at 1 week 14-16 HFEW 235 ± 24.7 mg, 18-20 V HFEW 213 ± 22.4 mg, laser 188 ± 18.7 mg (all p ≤ 0.001); 1 month post-op 14-16 V HFEW 275 ± 32.0 mg, 18-20 V HFEW 283 ± 31.0 mg, laser 276 ± 21.7 mg, rspectively (all p ≤ 0.0001). CONCLUSION: HFEW represents a novel technique for retinopexy during vitreoretinal surgery. It allows firm chorioretinal adhesion immediately after exposure. In non-vitrectomized eyes, using 14-16 V is particularly effective.

The price for reduced light toxicity: Do endoilluminator spectral filters decrease color contrast during Brilliant Blue G-assisted chromovitrectomy?

BACKGROUND: Vitreoretinal surgeons have been slow to adopt the use of spectral filters for endoillumination to reduce retinal light toxicity. This study shows that spectral filters can be used without a loss in color contrast during brilliant blue G chromovitrectomy. METHODS: To evaluate the influence of intra operative spectral light filters on perceivable contrast during Brilliant Blue G chromovitrectomy, a prospective, observational clinical study was carried out on 59 consecutive Brilliant Blue G chromovitrectomy interventions in 59 patients admitted for macular holes, macular pucker or vitreomacular traction syndromes. Subsequent to peeling of the internal limiting membrane, six different illumination modes were enabled consecutively: mercury vapor, mercury vapor/xenon, and xenon followed by xenon combined with an amber, green or yellow spectral filter. Main outcome measure was the chromaticity spread between stained internal limiting membrane and unstained retina as a measure for the color contrast perceived by the human eye. RESULTS: Mean chromaticity scores were similar for all light sources: mercury vapor 7.97, mercury vapor/xenon 7.96 (p = 0.96), and xenon 7.41 (p = 0.55). Compared to xenon, the additional use of endoillumination spectral filters did not change contrast recognizability: Chromaticity scores were 9.38 for the amber filter (p = 0.13), 6.63 for the green and 7.02 for the yellow filter (p = 0.37 and 0.64, respectively). When comparing the different filters head-to-head, the amber filter was superior to the green filter (p = 0.03), while the yellow was intermediate and not significantly different from either the amber (p = 0.08) or the green filter (p = 0.51). CONCLUSIONS: Color contrast perceptibility during Brilliant Blue G assisted chromovitrectomy is similar with mercury vapor, mercury vapor/xenon or xenon light sources. Spectral filters do not decrease color contrast recognizability. Head-to-head comparison shows a significant advantage for the amber over the green filter with respect to contrast generation, the yellow filter is intermediate. As spectral filters are known to greatly reduce retinal light toxicity, we suggest donor eye studies to validate whether the amber filter should be generally recommended for Brilliant Blue G chromovitrectomy.

Material properties of the internal limiting membrane and their significance in chromovitrectomy.

Intraoperative visualization of the internal limiting membrane (ILM), the choice of a point of vantage for lifting an initial flap, the precision with which the ILM is grasped, adhesion between the forceps and the ILM, thickness, stiffness and elasticity of the ILM as well as monitoring of the completeness of ILM removal are all important factors for safety and efficacy of a chromovitrectomy intervention. The understanding of the underlying physical features of the ILM, such as contrast behavior and bioanatomical and biomechanical properties represent, thus, useful prerequisites for successful macular surgery. New analytical tools, such as atomic force microscopy and chromaticity analysis, allow new insights into ILM material characteristics, permitting a systematic approach to refinement of surgical technique. .

Increase in lens capsule stiffness caused by vital dyes.

PURPOSE: To assess potential changes in lens capsule mechanical properties after staining with brilliant blue, indocyanine green (ICG), and trypan blue. SETTING: Department of Ophthalmology and Applied Physics and Center for NanoScience, Ludwig-Maximilians-University, Munich, Germany. DESIGN: Experimental study. METHODS: Fifteen unstained lens capsules were dissected into 7 wedge-shaped parts. Three fragments were stained with brilliant blue 0.025%, ICG 0.05%, and trypan blue 0.06%, respectively, for 1 minute. Another 3 specimens were additionally illuminated using a standard light source. The seventh part served as an untreated control. All specimens were analyzed using atomic force microscopy (AFM) in contact mode with a scan rate of 0.6 Hz. Two scan regions of 10 µm × 10 µm were chosen, and stiffness was determined using AFM in a force spectroscopy mode. The force curves were performed with a data rate of 5000 Hz. RESULTS: Staining of the samples resulted in an increase in tissue stiffness (brilliant blue: P<.001; ICG: P<.01; trypan blue: P<.05). Additional illumination after staining further increased tissue stiffness, but not significantly. Mean increase in the relative elasticity values were 1.61 ± 0.15 (SD) for brilliant blue, 2.04 ± 0.21 for brilliant blue with illumination, 1.63 ± 0.22 for ICG, 2.01 ± 0.22 for ICG with illumination, 1.23 ± 0.11 for trypan blue, and 1.39 ± 0.11 for trypan blue with illumination. In relation to unstained tissue, the relative elasticity of the stained tissue increased 1.2-fold after illumination. CONCLUSION: Staining significantly increased the mechanical properties of the human lens capsule. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Quantification of contrast recognizability in sequential epiretinal membrane removal and internal limiting membrane peeling in trypan blue-assisted macular surgery.

PURPOSE: To evaluate the selectivity and strength of intraoperative trypan blue staining during removal of epiretinal membranes (ERMs) and the internal limiting membrane. METHODS: Based on intraoperative videos, 51 consecutive chromovitrectomies in 51 patients with macular holes, macular pucker, vitreomacular traction syndromes, or persistent macular edema were retrospectively studied. Fifteen subjects underwent trypan blue, 14 indocyanine green, and 22 brilliant blue G chromovitrectomy. The main outcome measure was the color contrast between stained internal limiting membrane or ERM and the underlying unstained tissue by means of objective, quantitative, semiautomated chromaticity difference measurements. RESULTS: Trypan blue stains both ERM and the internal limiting membrane (average chromaticity scores 8.51 and 7.09, respectively; P = 0.48). Internal limiting membrane chromaticity scores were similar for trypan blue (7.09) and brilliant blue G (6.81; P = 0.71) but clearly higher for indocyanine green (15.81; P = 2.45 × 10). CONCLUSION: Under the premises of our study, trypan blue stains both ERM and the internal limiting membrane. Trypan blue's staining capacity of the internal limiting membrane is similar to that of brilliant blue G but significantly inferior compared with indocyanine green. Trypan blue, thus, represents a useful vital dye for chromovitrectomy, particularly in the presence of ERM, where it allows a sequential approach.

Contrast recognizability during brilliant blue G - and heavier-than-water brilliant blue G-assisted chromovitrectomy: a quantitative analysis.

PURPOSE: To evaluate the potential of heavier-than-water brilliant blue G (BBG-D(2) 0) to stain the internal limiting membrane (ILM) during chromovitrectomy. METHODS: In a nonrandomized, prospective, clinical multicentre study, 71 consecutive chromovitrectomy interventions in 71 patients were analysed. During routine 23-gauge vitrectomy, conventional 0.25 mg/ml BBG was employed in 21 and 0.25 mg/ml BBG-D(2) 0 in 50 patients. All interventions were videotaped. Post-operatively, video frames were viewed and dye performance assessed subjectively and objectively. Main outcome measure was the chromaticity difference between the stained ILM and the unstained underlying retina, measured by means of an objective and quantitative analysis method to describe colour contrast strengths as they are perceived by the human eye. RESULTS: Removal of the ILM was possible in all interventions without additional vital dyes. BBG-D(2) 0 readily sank to the retinal surface, while conventional BBG tended to swirl up throughout the vitreous cavity. Conventional BBG was removed either with active suction or with a flute needle. Brilliant blue G-D(2) 0 needed to be whirled up from the retinal surface with a flute needle before aspiration. Objective chromaticity measurements yielded a mean chromaticity score of 7.98 for BBG-D(2) 0 and 6.51 for BBG (p = 0.09). CONCLUSIONS: Brilliant blue G-D(2) 0 readily sinks to the retinal surface after injection and can be conveniently removed with a flute needle or active suction during chromovitrectomy. Based on the premises of the chromaticity measurements in this study, BBG's ILM staining capacity was not significantly improved through the recent revision its preparation, although a tendency towards slightly improved contrasts between the ILM and the underlying retina was observed.

Nanoscale topographic and biomechanical studies of the human internal limiting membrane.

PURPOSE: The purpose of this article was to create a nanometer scale topographic and biomechanical profile of the human internal limiting membrane (ILM) under native conditions. METHODS: ILMs from the posterior pole of postmortem human eyes were prepared as flat mounts and investigated by atomic force microscopy (AFM) under physiological conditions. Structural analysis was complemented by transmission electron microscopy. RESULTS: Average thickness of the fully hydrated, native ILMs was 3488 ± 460 nm. Thickness variations from 100 nm to 4326 nm characterized the fovea, which displayed a craterlike morphology. Outside the fovea, thickness distribution was uniform. Although mean ILM thicknesses were similar, standard deviation was higher on the retinal than on the vitreal side, indicating greater roughness. Average ILM stiffness was more than fivefold higher on the retinal than on the vitreal side (227 vs. 44 kPa). CONCLUSIONS: A detailed topographical and nanomechanical profile of native human ILM was generated using AFM. Thickness values were significantly higher than in previous studies because of the preservation of native conditions. Both thickness and stiffness showed marked variations around the fovea but were relatively uniform outside the foveal area. Interestingly, the foveal ILM displayed a craterlike morphological appearance with four distinct layers separated by comparatively steep thickness increments. ILM stiffness was considerably higher on the retinal than on the vitreal side. AFM opens new possibilities for investigating native basement membranes under physiological and pathological conditions. Transmission electron microscopy revealed higher extracellular matrix protein density on the retinal than on the vitreal side.

Changes in intraocular lens surface roughness during cataract surgery assessed by atomic force microscopy.

PURPOSE: To analyze the changes in optic surface roughness before and after injection of various intraocular lens (IOL) models using atomic force microscopy (AFM). SETTINGS: Departments of Ophthalmology, Medical University of Graz, General Hospital Linz and University Hospital Basel; Upper Austria University, School of Applied Health and Social Sciences, Linz, Austria. DESIGN: Experimental study. METHODS: The morphology and surface roughness of 3 hydrophobic acrylic IOLs from different manufacturers were analyzed by AFM in liquid using the tapping mode. First, AFM was performed on IOLs taken from the original package without further manipulation. In a second step, under sterile conditions, an experienced cataract surgeon loaded the IOLs into the appropriate injection system and pushed them through a system resembling an IOL implantation in cataract surgery; this was followed by AFM evaluation. Finally, 3 samples of a preloaded hydrophilic acrylic IOL taken from the original cartridge were compared with 3 samples that were pushed through the implantation system. RESULTS: Comparison of the arithmetic mean, standard deviation, root mean square, and surface skewness of the IOLs before and after injection showed a significant increase in surface roughness (P<.05). CONCLUSIONS: Standard application procedures of IOLs may alter the IOL surface. Increases in the surface roughness of IOLs may influence postoperative posterior capsule opacification. Further studies are necessary to evaluate the interfacial properties of IOLs.

Quantification of Contrast Recognizability during Brilliant Blue G- and Indocyanine Green-Assisted Chromovitrectomy.

PURPOSE: To evaluate the potential of brilliant blue G (BBG) and indocyanine green (ICG) for intraoperative staining of the internal limiting membrane (ILM) with respect to perceivable contrast. METHODS: In a retrospective clinical case series the authors analyzed 26 consecutive chromovitrectomy interventions in 26 patients with macular holes, epiretinal fibrosis, vitreoretinal traction syndromes, or persistent macular edema. Fourteen subjects underwent ICG and 12 subjects, BBG chromovitrectomy. The main outcome measure was the difference in chromaticity between the stained ILM and the unstained underlying retina, measured by means of a novel objective and quantitative video-based analysis method to describe color contrast strengths as they are perceived by the human eye. RESULTS: Objective chromaticity measurements of the intraoperative videos of all 26 interventions showed a significantly inferior contrast for BBG compared with that of ICG (BBG = 6.1, ICG = 14.9; P = 3.885 × 10⁻¹5). CONCLUSIONS: As an adjunct to chromovitrectomy to stain the ILM, BBG yields a significantly less well discernible contrast to the human eye than that of ICG under the premises of this study.

Sequential epiretinal membrane removal with internal limiting membrane peeling in brilliant blue G-assisted macular surgery.

PURPOSE: To assess the selectivity of brilliant blue G (BBG) staining by analysing the morphological components of unstained and stained tissue obtained during epiretinal membrane (ERM) removal with internal limiting membrane (ILM) peeling in BBG-assisted macular surgery. METHODS: Twenty-six surgical specimens were removed from 13 eyes with epiretinal gliosis during vitrectomy using BBG for ERM and ILM peeling. We included eyes with idiopathic macular pucker, idiopathic macular hole and vitreomacular traction syndrome. The dye was injected into the fluid-filled globe. Unstained and stained epiretinal tissue was harvested consecutively and placed into separate containers. All specimens were processed for conventional transmission electron microscopy. RESULTS: The first surgical specimen of all eyes showed no intraoperative staining with BBG and corresponded to masses of cells and collagen. The second surgical specimen demonstrated good staining characteristics and corresponded to the ILM in all patients included. In seven eyes, the ILM specimens were seen with minor cell proliferations such as single cells or a monolayer of cells. Myofibroblasts, fibroblasts and astrocytes were present. In five cases, native vitreous collagen fibrils were found at the ILM. In six of the eyes, ILM specimens were blank. CONCLUSION: Our clinicopathological correlation underlines the selective staining properties of BBG. The residual ILM is selectively stained by BBG even when a small amount of cells and collagen adheres to its vitreal side. To reduce the retinal exposure to the dye, the surgeon might choose to remove the ERM without using the dye, followed by a BBG injection to identify residual ILM.

Anatomical and functional outcome in brilliant blue G assisted chromovitrectomy.

PURPOSE: To evaluate the potential of brilliant blue G (BBG) for intraoperative staining of the inner limiting membrane (ILM) with respect to staining properties and surgical outcome. METHODS: In a retrospective, non-comparative clinical case series, we analysed 17 consecutive chromovitrectomy interventions for surgery of macular holes, ERMs, vitreoretinal traction syndromes and cystoid macular oedema. Following complete posterior vitreous detachment, BBG was injected into the vitreous cavity at a concentration of 0.25 mg/ml, followed by immediate washout. Main outcome measures were staining properties, visual acuity, central visual field testing and optical coherence tomography (OCT) measurements over a mean follow-up period of 3 months. RESULTS: ILM staining was somewhat less intensive for BBG than for average indocyanine green (ICG) chromovitrectomy. However, the ILM was removed successfully without additional ICG in 15/17 patients. Postoperative visual acuity was improved in 16/17 patients and remained unchanged in one patient. Central retinal OCT thickness showed a postoperative reduction, with values ranging from +7 to -295 microm (median -89 microm). Neither visual field defects nor any other adverse events were recorded. CONCLUSION: BBG permits sufficient staining for safe ILM removal. In this short-term study, good anatomical and functional results were achieved and no adverse events were observed.