Enzymatic vitreolysis with ocriplasmin for vitreomacular traction and macular holes.

BACKGROUND: Vitreomacular adhesion can lead to pathologic traction and macular hole. The standard treatment for severe, symptomatic vitreomacular adhesion is vitrectomy. Ocriplasmin is a recombinant protease with activity against fibronectin and laminin, components of the vitreoretinal interface. METHODS: We conducted two multicenter, randomized, double-blind, phase 3 clinical trials to compare a single intravitreal injection of ocriplasmin (125 µg) with a placebo injection in patients with symptomatic vitreomacular adhesion. The primary end point was resolution of vitreomacular adhesion at day 28. Secondary end points were total posterior vitreous detachment and nonsurgical closure of a macular hole at 28 days, avoidance of vitrectomy, and change in best-corrected visual acuity. RESULTS: Overall, 652 eyes were treated: 464 with ocriplasmin and 188 with placebo. Vitreomacular adhesion resolved in 26.5% of ocriplasmin-injected eyes and in 10.1% of placebo-injected eyes (P<0.001). Total posterior vitreous detachment was more prevalent among the eyes treated with ocriplasmin than among those injected with placebo (13.4% vs. 3.7%, P<0.001). Nonsurgical closure of macular holes was achieved in 40.6% of ocriplasmin-injected eyes, as compared with 10.6% of placebo-injected eyes (P<0.001). The best-corrected visual acuity was more likely to improve by a gain of at least three lines on the eye chart with ocriplasmin than with placebo. Ocular adverse events (e.g., vitreous floaters, photopsia, or injection-related eye pain--all self-reported--or conjunctival hemorrhage) occurred in 68.4% of ocriplasmin-injected eyes and in 53.5% of placebo-injected eyes (P<0.001), and the incidence of serious ocular adverse events was similar in the two groups (P=0.26). CONCLUSIONS: Intravitreal injection of the vitreolytic agent ocriplasmin resolved vitreomacular traction and closed macular holes in significantly more patients than did injection of placebo and was associated with a higher incidence of ocular adverse events, which were mainly transient. (Funded by ThromboGenics; ClinicalTrials.gov numbers, NCT00781859 and NCT00798317.).

Efficacy of intravitreal ocriplasmin for treatment of vitreomacular adhesion: subgroup analyses from two randomized trials.

PURPOSE: To evaluate the efficacy of a single intravitreal injection of ocriplasmin 125 µg across relevant subpopulations of patients with symptomatic vitreomacular adhesion (VMA)/vitreomacular traction (VMT), including when associated with macular hole. DESIGN: Two multicenter, randomized, placebo-controlled, double-masked, 6-month studies. PARTICIPANTS: A total of 652 randomized patients (464 receiving ocriplasmin; 188 receiving placebo). METHODS: A single intravitreal injection of ocriplasmin 125 µg or placebo in the study eye. MAIN OUTCOME MEASURES: Prespecified subgroup analyses were conducted to evaluate the effects on the proportion of patients with nonsurgical resolution of focal VMA at day 28, nonsurgical full-thickness macular hole (FTMH) closure at month 6, and categoric improvement in best-corrected visual acuity (BCVA) at month 6. RESULTS: Resolution of VMA at day 28 was achieved more often in younger patients (<65 years), eyes without epiretinal membrane, eyes with FTMH, phakic eyes, and eyes with a focal VMA ≤ 1500 µm. Eyes with FTMH width ≤ 250 µm were more likely to achieve nonsurgical FTMH closure. Categoric ≥ 2-line and ≥ 3-line improvement in BCVA occurred more often in younger patients (<65 years) and in patients with a lower baseline BCVA (<65 letters). Treatment differences in favor of ocriplasmin were generally observed across each subgroup of subpopulations studied. CONCLUSIONS: Subgroup analyses confirmed the positive effect of ocriplasmin across relevant subpopulations.

Cells at the vitreoretinal interface in small full-thickness macular holes.

PURPOSE: To report on total number, distribution, and type of cells at the vitreomacular interface in small full-thickness macular holes. METHODS: Internal limiting membrane specimens were removed from 20 consecutive patients with macular holes <250 µm at times when pharmacologic vitreolysis was not available. Specimens were flat mounted and investigated by phase contrast and interference microscopy and immunocytochemistry. Clinical data were documented including optical coherence tomography analysis using the caliper function. Thirteen antibodies were used for glial cells, hyalocytes, macrophages, retinal pigment epithelial cells, different types of collagen, alpha-smooth muscle actin, and proliferating cells. RESULTS: There was a positive correlation between macular hole size and cell density at the internal limiting membrane (Spearman's Rho: r = 0.519, P = 0.019). Mostly, single glial cells were found on the internal limiting membrane. In five patients, cell clusters were present. There was a strong immunoreactivity for glial cell markers. Immunoreactivity of hyalocyte markers, alpha-smooth muscle actin, and Ki-67 was found in cell clusters but otherwise sparse. CONCLUSION: Single cells of glial origin without signs of proliferation or contraction are present in eyes with small full-thickness macular holes. In some eyes, however, clusters of cells can be seen, capable of proliferation and exerting tangential traction. Our findings emphasize the need for better visualization of the vitreoretinal pathology by optical coherence tomography, especially to distinguish between single cells and cell clusters.

Association between anatomical resolution and functional outcomes in the mivi-trust studies using ocriplasmin to treat symptomatic vitreomacular adhesion/vitreomacular traction, including when associated with macular hole.

PURPOSE: To evaluate visual function in patients with symptomatic vitreomacular adhesion (VMA)/vitreomacular traction including when associated with macular hole after ocriplasmin treatment, and the association between resolution of the underlying condition and improvement in visual function. METHODS: Six hundred and fifty-two patients from 2 Phase 3 trials received a single intravitreal injection of ocriplasmin 125 µg (n = 464) or placebo (n = 188). Mean and categorical changes from baseline in best-corrected visual acuity and 25-item Visual Function Questionnaire scores were used to evaluate visual function. Subgroups with VMA resolution and full-thickness macular hole closure were compared. RESULTS: Overall, 42% of patients who achieved VMA resolution at Day 28 had a ≥2-line improvement in best-corrected visual acuity at Month 6, and 20% had a ≥3-line improvement. Likewise, 69% of patients with nonsurgical full-thickness macular hole closure at Day 28 had a ≥2-line improvement at Month 6, and 48% had a ≥3-line best-corrected visual acuity improvement. Mean improvements in 25-item Visual Function Questionnaire scores were associated with achieving VMA resolution and nonsurgical full-thickness macular hole closure. CONCLUSION: In patients with symptomatic VMA/vitreomacular traction, VMA resolution and nonsurgical full-thickness macular hole closure were each associated with improvements in visual function. Resolving the underlying anatomical condition in symptomatic VMA/vitreomacular traction will increase the probability of achieving a clinically meaningful improvement in visual function.

Hyalocytes in idiopathic epiretinal membranes: a correlative light and electron microscopic study.

PURPOSE: To describe characteristics of epiretinal cells at the vitreoretinal interface by correlative light and electron microscopy (CLEM). METHODS: Epiretinal membrane (ERM) specimens and internal limiting membrane (ILM) specimens were harvested by sequential peeling during vitrectomy from 27 eyes with idiopathic epiretinal gliosis, and processed for CLEM. Intraoperatively, the presence of posterior vitreous detachment (PVD) was documented. We used anti-vimentin, anti-α-smooth muscle actin (α-SMA), and anti-CD45 as primary antibodies. A fluorescein-tagged immunonanogold cluster was used as secondary antibody and visualized under the fluorescence and transmission electron microscope. RESULTS: We demonstrated CD45-positive cells specifically labelled at their plasma membranes with ultrastructural features known for hyalocytes, such as oval nucleus with marginal chromatin, vacuoles, dense granules, and thin cytoplasmic protrusions. CD45-positive cells were mostly located on a thick layer of native vitreous collagen. They were covered by newly formed collagen strands with multilayered proliferation of myofibroblasts. We also demonstrated immunoreactivity for vimentin and alpha-SMA. Cell fragments with positive labelling for α-SMA and vimentin were not only found on the vitreal side of the ILM, but also on the retinal side. CONCLUSIONS: By CLEM, the majority of CD45-positive cells in epiretinal cell proliferation were characterized as hyalocytes. In the context of anomalous PVD and vitreoschisis, ultrastructural features and topographic localization of hyalocytes suggest that these cells play a significant role in ERM formation. CLEM enables a more accurate characterization of epiretinal cell proliferation, and therefore, contributes to a better understanding of the pathogenesis of diseases at the vitreoretinal interface.

Epiretinal cell proliferation in macular pucker and vitreomacular traction syndrome: analysis of flat-mounted internal limiting membrane specimens.

PURPOSE: To describe new details of epiretinal cell proliferation in flat-mounted internal limiting membrane specimens. METHODS: One hundred nineteen internal limiting membrane specimens were removed en bloc with epiretinal membranes from 79 eyes with macular pucker (MP) and 40 eyes with vitreomacular traction syndrome. Intraoperatively, posterior vitreous detachment was assessed as complete or incomplete. Whole specimens were flat-mounted on glass slides and processed for interference and phase-contrast microscopy, cell viability assay, and immunocytochemistry. RESULTS: Mean cell viability percentage was higher in MP than in vitreomacular traction syndrome. Two cell distribution patterns were found. Anti-CD163 labeling presented predominantly in MP with complete posterior vitreous detachment. CD45 expression was similar in all groups of diagnosis. Anti-glial fibrillary acidic protein (GFAP) labeling was found in MP irrespective of the extent of posterior vitreous detachment. Alpha-SMA (α-smooth muscle actin) labeling was mainly presented in MP with incomplete posterior vitreous detachment and in vitreomacular traction syndrome. Simultaneous antibody labeling included GFAP/CD45, GFAP/CD163, CD163/CD45, and CD163/α-SMA. CONCLUSION: Hyalocytes constitute a major cell type of epiretinal cell proliferation in eyes with MP and vitreomacular traction syndrome. Glial cells, notably retinal Muller cells, are involved as well. It appears that transdifferentiation of cells in vitreomacular traction might be more frequent than previously thought and that those cells possess a greater variability of immunocytochemical properties than expected.

Oct-based interpretation of the vitreomacular interface and indications for pharmacologic vitreolysis.

PURPOSE: To review the role of optical coherence tomography (OCT) in diagnosis and management of vitreomacular disease and the impact of OCT on potential uses of ocriplasmin, a new pharmacologic vitreolysis agent recently approved by the U.S. Food and Drug Administration for the treatment of symptomatic vitreomacular adhesion. METHODS: Analysis of current literature regarding OCT in diagnosis and management of vitreomacular interface disease. RESULTS: Posterior vitreous detachment is typically a nonpathologic age-related event. Anomalous posterior vitreous detachment emerges when the vitreous cortex fails to cleanly detach from the macula, optic nerve, or other adherent sites. Focal vitreomacular adhesion is a nonpathologic anatomical designation associated with perifoveal posterior vitreous detachment but normal retinal morphology on OCT. Vitreomacular traction is a pathologic consequence of persistent vitreous attachment with structural disturbance of the macular retina visible on OCT. Full-thickness macular holes are foveal defects continuous through all retinal layers to the retinal pigment epithelium. Vitreomacular traction and macular hole with focal vitreomacular adhesion are indications for pharmacologic vitreolysis. CONCLUSION: Noninvasive high-resolution OCT imaging has transformed the understanding of vitreomacular interface disease. Careful evaluation of the vitreomacular interface with OCT has increased in importance with the introduction of ocriplasmin for vitreomacular adhesion associated with symptomatic anatomical retinal changes.

Residual cellular proliferation on the internal limiting membrane in macular pucker surgery.

PURPOSE: To provide pathology data on the completeness of epiretinal membrane (ERM) removal with and without internal limiting membrane (ILM) peeling. METHODS: Twenty-two patients with idiopathic ERM formation underwent vitrectomy with ERM removal and subsequent staining of the vitreomacular interface with brilliant blue. If the ILM was still present after ERM removal, it was peeled off. Both ERM and ILM specimens were harvested in different containers and prepared for flat-mount phase-contrast and interference microscopy, immunocytochemistry, and transmission electron microscopy. RESULTS: In 14 patients (64%), the ILM was still present at the macula after ERM removal. On average, 20% (range, 2-51%) of the total cell count was left behind at the ILM if the ERM was removed only. There were mainly glial cells on the ILM, and few hyalocytes. In nine eyes, the cells were forming cell clusters. In 8 patients (36%), both ERM and ILM were removed together. Electron microscopy showed cellular proliferation directly attached to the ILM in these eyes, whereas in the sequentially peeled group, there was collagen interposed between the ERM and the ILM. Surgical ERM removal resulted in splitting of the vitreous cortex in these eyes, leaving the ILM with residual cells behind. CONCLUSION: Simple ERM removal results in sufficient separation of fibrocellular tissue in one third of cases, only. In 2 of 3 patients with idiopathic ERM, the vitreous cortex splits when the ERM is removed, leaving an average of 20% of the total cell count behind on the ILM. As these cells are capable of proliferation and causing ERM recurrence, staining of the ILM with subsequent removal seems beneficial in macular pucker surgery.

Pores of the inner limiting membrane in flat-mounted surgical specimens.

PURPOSE: To demonstrate the incidence of pores in the inner limiting membrane (ILM) in flat-mounted ILM specimens and to show the immunocytochemical properties of cellular proliferation associated with them. METHODS: One hundred and twelve ILM specimens from patients with idiopathic macular holes were flat mounted and screened for pores. The ILM was assessed by phase-contrast and interference microscopy. Various antibodies were used against glial cells, hyalocytes, and retinal pigment epithelial cells. RESULTS: In total, only three pores were found. They were characterized by a full-thickness defect of the ILM with irregular borders and cellular proliferation on the ILM. Glial cells were seen in direct association with the ILM pore. Glial cell and hyalocyte markers were the main immunologic features observed. CONCLUSION: Inner limiting membrane pores are a rare finding. Glial cells are likely to cross the ILM through these pores on their way from the retina to the vitreoretinal border. Given the frequency of cellular proliferation and the rare finding of ILM pores, other pathways have to be considered in playing the leading role in epiretinal proliferation. They might include migration of cells through ILM thinning along retinal vessels and proliferation of vitreous cortex hyalocytes at the vitreoretinal border.

Ultrastructure and retinal imaging of epiretinal membrane: a clinicopathologic correlation of trypan blue staining in epiretinal membrane surgery.

PURPOSE: The purpose of this study was to correlate the ultrastructural morphology of epiretinal tissue with optical coherence tomography and to investigate the effects of trypan blue staining on epiretinal membrane (ERM) ultrastructure and clinical outcome. METHODS: A prospective, case-comparative study. Consecutive patients were recruited and underwent vitrectomy and ERM peeling with 0.15% trypan blue; these patients were compared with a control group peeled without stain. Optical coherence tomography was performed preoperatively and at 10 days and 3 months postoperatively. Data were collected prospectively to include Snellen visual acuity and surgical ERM characteristics. Epiretinal tissue was examined using transmission electron microscopy. RESULTS: Thirty-seven patients underwent ERM surgery, and 34 had complete data, of which 18 had peeling of unstained and 16 had peeling of stained ERM. Staining resulted in a significantly greater postoperative reduction in macular thickness compared with the unstained group. There was no significant difference in the visual outcome and no ultrastructural evidence of alteration of the cleavage plane in cases in which trypan blue was used. CONCLUSION: There was no clinical or ultrastructural evidence of toxicity in peeling with trypan blue.

Ultrastructure and retinal imaging of internal limiting membrane: a clinicopathologic correlation of trypan blue stain in macular hole surgery.

PURPOSE: The purpose of this study was to correlate the ultrastructural morphology of epiretinal and retinal tissue with optical coherence tomography assessment and to investigate the effects of trypan blue staining on internal limiting membrane (ILM) tissue. METHODS: This was a prospective case-comparative study. Consecutive patients were recruited and underwent ILM peel with 0.5 mL of 0.15% trypan blue, and these were compared with a nonrandomized control group (unstained ILM). Patients underwent optical coherence tomography scanning preoperatively and postoperatively at 1.5 and 3 months. Data were collected prospectively to include Snellen visual acuity, macular hole, and operative characteristics. Internal limiting membrane was examined by transmission electron microscopy. RESULTS: Sixty-four patients underwent macular hole surgery, and complete data were available on 49 patients (17 control subjects and 32 patients who had peeling of stained ILM). Trypan blue staining significantly improved ease and completeness of ILM removal. There was no significant difference in vision, optical coherence tomography characteristics, or macular hole closure rate at 3 months between stained and unstained groups. There was no ultrastructural evidence of alteration of the plane of ILM separation in cases in which trypan blue was used. CONCLUSION: Trypan blue stain from these data seems to improve the ease and completeness of the ILM peeling (assessed clinically) and does not show any signs of toxicity.

Microplasmin intravitreal administration in patients with vitreomacular traction scheduled for vitrectomy: the MIVI I trial.

PURPOSE: To evaluate the safety and preliminary efficacy of 4 doses and several exposure times of intravitreal microplasmin given before pars plana vitrectomy for vitreomacular traction maculopathy. DESIGN: A multicenter, prospective, uncontrolled, dose-escalation, phase I/II clinical trial. PARTICIPANTS: Sixty patients enrolled into 6 successive cohorts. INTERVENTION: A single intravitreal injection of microplasmin at 1 of 4 doses (25, 50, 75, or 125 microg in 100 microl) administered either 1 to 2 hours, 24 hours, or 7 days before planned pars plana vitrectomy. MAIN OUTCOME MEASURES: For safety, a complete ophthalmologic examination, fundus photography, fluorescein angiography, Humphrey visual fields, and electrophysiology; for efficacy, posterior vitreous detachment (PVD) induction as assessed by B-scan ultrasound and ease of PVD induction at the time of vitrectomy. RESULTS: The use of microplasmin led to a progressively higher incidence of PVD induction on ultrasonography with increasing time exposure. A PVD before surgery was observed with 25 microg microplasmin in 0, 2, and 5 patients with increasing exposures (2 hours, 24 hours, 7 days). With increasing dose, a PVD before surgery was observed by ultrasound as follows: 25 microg, 0; 50 microg, 1; 75 microg, 2; 125 microg, 3. However, at surgery, with a 125-microg dose, these patients had a discontinuous layer of vitreous present on the retinal surface resulting from the induction of an anomalous PVD in the form of vitreoschisis. One retinal detachment developed shortly after administration of microplasmin. Two developed after surgery. There were no other safety concerns. CONCLUSIONS: Results from this initial clinical trial evaluating intravitreal microplasmin show the drug to be well tolerated and capable of inducing a pharmacologic PVD in some patients. These results warrant evaluation of microplasmin in larger, controlled trials.

Objective of pharmacologic vitreolysis.

The goal of pharmacologic vitreolysis is to cleave the vitreoretinal junction, thereby inducing posterior vitreous detachment (PVD), and to liquefy the vitreous gel. There are several reasons to pursue a pharmacologic approach: (1) Mechanical vitrectomy is incomplete. Both at the posterior pole and in the retinal periphery, remnants of the cortical vitreous are left behind at the internal limiting membrane of the retina, causing vitreoretinal traction and (re)proliferation of cells, and leading to surgical failure. (2) Pharmacologic vitreolysis offers complete PVD without mechanical manipulation at the vitreoretinal interface, such as ILM peeling, thereby minimizing the risk of iatrogenic damage to the macula. (3) An intravitreal injection resulting in complete PVD is a less traumatic approach than vitrectomy, and it might be beneficial as prophylactic treatment regime in retinal diseases characterized by fibrocellular and fibrovascular proliferation at the vitreoretinal interface, such as diabetic macular edema and proliferative retinopathy, in order to prevent advanced stages of disease. (4) Cleaving the cortical hyaloid completely from the retina changes the molecular flux across the vitreoretinal interface and improves oxygen supply to the retina, a major mechanism of action which might significantly interfere with biochemical pathways of retinal hypoxia, leading to an overexpression of vasoactive substances such as vascular endothelial growth factor.

Microplasmin-assisted vitrectomy.

Microplasmin (Thrombogenics Ltd., Leuven, Belgium) is a recombinant molecule consisting of the catalytic domain of human plasmin. It is highly characterized, and supplied in a stabilized form, simplifying storage and administration. Microplasmin shares the same catalytic properties like human plasmin, but it is much more stable compared to plasmin. It has been shown previously that both plasmin and microplasmin are capable of inducing PVD. This chapter focuses on one of the most promising current concepts of pharmacologic vitreolysis, i.e. microplasmin-assisted vitrectomy. We report on the preclinical work of plasmin and microplasmin which lead to the clinical investigation of microplasmin in different clinical trials, the so-called MIVI trials.

Vital dyes for macular surgery: a comparative electron microscopy study of the internal limiting membrane.

PURPOSE: To analyze and compare the ultrastructure of the retinal cleavage plane of the internal limiting membrane (ILM) removed during dye-assisted macular surgery. METHODS: Ninety-six surgical specimens of the ILM obtained during trypan blue (TB)-, brilliant blue G (BBG)-, bromphenol blue (BPB)-, Chicago blue (CB)-, and indocyanine green-assisted pars plana vitrectomy for idiopathic macular hole and macular pucker were evaluated using transmission electron microscopy. Specimens removed without dye assistance served as controls. RESULTS: Specimens removed after TB-, BBG-, BPB-, and CB-staining presented with significantly less cellular fragments (in size and quantity) at the retinal side of the ILM than specimens after indocyanine green staining. Large cellular fragments and Müller cell endfeet, which were typically present after indocyanine green staining, were not found after TB, BBG, BPB, and CB staining. Comparing all groups, TB was found with less retinal debris than BBG, BPB, and CB. Specimens removed without intravitreal dye administration showed the least retinal fragments that were solitarily distributed at the ILM. CONCLUSION: Trypan blue, BBG, BPB, and CB cause significantly less morphologic changes at the retinal cleavage plane than indocyanine green. Further studies are required to elucidate if presence and amount of retinal cell fragments at ILM specimens correlate with functional deficits.

Pathology of the macular hole rim in flat-mounted internal limiting membrane specimens.

PURPOSE: The purpose of this study was to image the pathology of vitreoretinal adhesion and cellular proliferation at the macular hole rim for a better understanding of macular hole formation. METHODS: Internal limiting membrane (ILM) peeling, ILM flat-mount preparation, phase contrast and interference microscopy, transmission electron microscopy, and immunocytochemistry of the macular hole rim were performed in 10 eyes with idiopathic macular holes. RESULTS: Phase contrast and interference microscopy showed cellular proliferation on the vitreal side of the ILM in all specimens. There were single cells in three eyes, cell clusters in six eyes, and continuous proliferation in one eye. Surrounding the macular hole, only a few cells were present. Cellular proliferation started at a distance of 80 mum to 940 mum from the macular hole edge. Transmission electron microscopy showed vitreous adhesion at the macular hole rim. In ultrastructural terms, there was a continuous insertion of vitreous collagen fibers into the ILM. Immunocytochemistry was positive for collagen type II, laminin, and fibronectin in the area of vitreous attachment. Cells were stained with markers for glial cells, retinal pigment epithelial cells, and hyalocytes. CONCLUSION: There is ultrastructural evidence that macular hole formation is caused by an insertion of the cortical vitreous into the foveal ILM. Vitreous collagen fibers may exert vitreofoveal traction, resulting in a foveal tear. Cellular proliferation is not continuously distributed surrounding the macular hole but separated from the macular hole edge and seems to originate from cell clusters forming centers of proliferation distant from the macular hole rim.

Functional outcome of indocyanine green-assisted macular surgery: 7-year follow-up.

PURPOSE: To evaluate the long-term functional results after surgery for macular pucker and macular holes with indocyanine green (ICG) staining of the internal limiting membrane. METHODS: Long-term functional and anatomical outcomes of 16 eyes of 16 patients were evaluated for 7.3 years after ICG-assisted macular surgery. Examinations performed included best-corrected visual acuity, Goldmann perimetry, Arden color contrast test, optical coherence tomography, and fundus photography. Ten eyes had undergone surgery for macular holes, and 6 eyes had been treated for macular pucker. Indocyanine green with a concentration of 0.05% and an osmolarity of 275 mOsm had been used to stain the internal limiting membrane. RESULTS: Mean follow-up time was 7.3 years. Eighty-eight percent (14) of the eyes had undergone cataract surgery either in a combined intervention primarily (n = 3) or in the years after the ICG-assisted macular surgery (n = 11). One patient was still phakic with a pronounced cataract at last follow-up. Over all patients, best-corrected visual acuity did not increase significantly from 20/200 (median) before macular surgery to the present 20/70 (median). Large visual field defects (VFDs) were found in 10 of 16 patients after internal limiting membrane staining using ICG. In 8 of these 10 eyes, the VFDs had been diagnosed immediately after vitrectomy and remained unchanged throughout the period of review. In 2 eyes, a VFD was noted at the last follow-up visit despite an unremarkable Goldmann perimetry performed at follow-up visits after 3 months and 6 months. Pathologic color testing was found in 15 of 16 patients when comparing the operated and the fellow eye. A nonglaucomatous optic nerve atrophy was found in 11 of 16 eyes. The optical coherence tomography revealed macular hole closure in all 10 patients. CONCLUSION: Indocyanine green-assisted macular surgery might lead to optic nerve atrophy in the long-term and persistent VFDs. In addition, new VFDs may occur in the postoperative course. An affection of color vision also underlines the potential impact of ICG on visual function. A long-term observation of patients after ICG-assisted vitrectomy seems mandatory to reliably detect functional adverse events.

Experimental evaluation of microplasmin - an alternative to vital dyes.

Complete separation of the vitreous from the retina is a major goal of vitrectomy. Mechanical vitrectomy, however, is not able to meet this need because remnants of the vitreous cortex are left behind at the retinal surface, resulting in incomplete posterior vitreous detachment (PVD). As incomplete PVD and an attached vitreous cortex are associated with the progression of common retinal diseases including diabetic retinopathy and maculopathy, central retinal vein occlusion, and proliferative vitreoretinopathy, induction of complete PVD is a major issue both in vitreoretinal surgery and in medical retina. This chapter focuses on one of the most promising current concepts of pharmacologic vitreolysis, i.e. microplasmin-assisted vitrectomy. Microplasmin (Thrombogenics Ltd., Dublin, Ireland) is a recombinant molecule consisting of the catalytic domain of human plasmin. It shares the same catalytic properties like human plasmin, but it is much more stable compared to plasmin. It has been shown previously that both plasmin and microplasmin are capable of inducing PVD. Herein, we report on the preclinical work regarding plasmin and microplasmin which led to the clinical investigation of microplasmin.

Toxicity of indocyanine green in vitreoretinal surgery.

Indocyanine green (ICG) selectively stains the internal limiting membrane (ILM) of the retina, and helps to visualize and remove the membrane from the retina. Toxicity and damage to the retina has been reported in in vitro and in vivo studies, and following macular surgery. Toxic effects can occur to retinal glial cells, to the nerve fiber layer, to retinal ganglion cells, and to the optic nerve. In case of subretinal application, the retinal pigment epithelium can be affected. The mechanisms of toxicity are unclear. Whether the dye itself or some preparations only are causing harm to the retina is subject of an ongoing debate. ICG changes the light absorption properties of the ILM and enhances the stiffness of the membrane, probably by crosslinking of collagen fibers. Beside better visualization, this effect is responsible for the ease of membrane removal compared to unaided ILM peeling. Whether a phototoxic effect, which has been demonstrated in vitro and in vivo, plays a clinically significant role in macular surgery has neither been proven nor ruled out yet. ICG at concentrations higher than 1.25% or application of the dye in air are very likely causing retinal damage. In addition, lower concentrations also carry the risk of iatrogenic damage, depending on the final concentration of potentially toxic substances at the vitreomacular interface and on other mechanisms. Due to its instability and the unpredictable effects of ICG at the macula, it cannot be recommended for clinical use before its safety has been proven. This chapter reviews the literature related to ICG toxicity, and summarizes dye-related untoward effects in postmortem eyes and ex vivo models, in in vitro and in vivo animal models, and in macular surgery.

An experimental approach towards novel dyes for intraocular surgery.

Chromovitrectomy represents a recent development in the field of vitreoretinal surgery. Several dyes are available for intraocular application with different staining characteristics. Before the intraoperative use in humans, new dyes need to be evaluated thoroughly in experimental in vivo and ex vivo studies in order to detect potential adverse effects related to dye toxicity. This article describes a reasonable approach for the assessment of novel dyes prior to the use in humans.