Nationwide genetic analysis of more than 600 families with inherited eye diseases in Argentina.

This study corresponds to the first large-scale genetic analysis of inherited eye diseases (IED) in Argentina and describes the comprehensive genetic profile of a large cohort of patients. Medical records of 22 ophthalmology and genetics services throughout 13 Argentinian provinces were analyzed retrospectively. Patients with a clinical diagnosis of an ophthalmic genetic disease and a history of genetic testing were included. Medical, ophthalmological and family history was collected. A total of 773 patients from 637 families were included, with 98% having inherited retinal disease. The most common phenotype was retinitis pigmentosa (RP, 62%). Causative variants were detected in 379 (59%) patients. USH2A, RPGR, and ABCA4 were the most common disease-associated genes. USH2A was the most frequent gene associated with RP, RDH12 early-onset severe retinal dystrophy, ABCA4 Stargardt disease, PROM1 cone-rod dystrophy, and BEST1 macular dystrophy. The most frequent variants were RPGR c.1345 C > T, p.(Arg449*) and USH2A c.15089 C > A, p.(Ser5030*). The study revealed 156/448 (35%) previously unreported pathogenic/likely pathogenic variants and 8 possible founder mutations. We present the genetic landscape of IED in Argentina and the largest cohort in South America. This data will serve as a reference for future genetic studies, aid diagnosis, inform counseling, and assist in addressing the largely unmet need for clinical trials to be conducted in the region.

Orbital compartment syndrome due to periorbital angioedema.

A 68-year-old female presented with an episode of unilateral orbital compartment syndrome due to periorbital angioedema. The patient made a consultation at the general Emergency Room with sudden left periorbital edema and serious diminished ipsilateral visual acuity, with examination detecting orbital compartment syndrome secondary to a probable allergic angioedema after ingestion of ibuprofen. She received treatment with intravenous and oral corticosteroids, achieving a rapid improvement in the condition and clinical follow-up was carried out, with evaluation of the peripapillary retinal nerve fiber layer thickness and computed perimetry. Periorbital angioedema due to ibuprofen can be a cause of orbital compartment syndrome whose diagnosis and treatment must be carried out urgently to prevent permanent visual impairment.

Quantification of Vascular Parameters in Whole Mount Retinas of Mice with Non-Proliferative and Proliferative Retinopathies.

Retinopathies are a heterogeneous group of diseases that affect the neurosensory tissue of the eye. They are characterized by neurodegeneration, gliosis and a progressive change in vascular function and structure. Although the onset of the retinopathies is characterized by subtle disturbances in visual perception, the modifications in the vascular plexus are the first signs detected by clinicians. The absence or presence of neovascularization determines whether the retinopathy is classified as either non-proliferative (NPDR) or proliferative (PDR). In this sense, several animal models tried to mimic specific vascular features of each stage to determine the underlying mechanisms involved in endothelium alterations, neuronal death and other events taking place in the retina. In this article, we will provide a complete description of the procedures required for the measurement of retinal vascular parameters in adults and early birth mice at postnatal day (P)17. We will detail the protocols to carry out retinal vascular staining with Isolectin GSA-IB4 in whole mounts for later microscopic visualization. Key steps for image processing with Image J Fiji software are also provided, therefore, the readers will be able to measure vessel density, diameter and tortuosity, vascular branching, as well as avascular and neovascular areas. These tools are highly helpful to evaluate and quantify vascular alterations in both non-proliferative and proliferative retinopathies.

Rubeosis iridis and macular hemorrhages from multiple Corkscrew retinal vessels in a patient with NF1.

PURPOSE: To report a case of a patient with NF1 presenting with ocular findings of AV malformation, multiple retinal hemorrhages, and neovascular glaucoma in the absence of retinal ischemia. METHODS: Review of the medical record was conducted in accordance with the local IRBt. RESULTS: A 60-year-old female patient with diagnosis of Neurofibromatosis type1 (NF1) and sudden decrease of vision in her left eye was found to have rubeosis iridis and high intraocular pressure (IOP). On fundus exam multiple corkscrew retinal vessels and retinal hemorrhages were present in her left eye. On Optical Coherence Tomography (OCT) the foveal hemorrhages appeared as outer layer hyperreflective retinal infiltrates whereas in the parafoveal area the hyperreflectivity was present between the RPE and neurosensory retina. Fluorescein Angiogram (FA) showed normal perfusion and no areas of leakage or ischemia. Treatment with anti-angiogenics in a timely manner correlated with a good visual outcome. CONCLUSIONS: We present a unique patient with NF1, rubeosis iridis, high IOP, and macular hemorrhages from multiple corkscrew retinal vessels in a well perfused retina, who underwent treatment with a single dose of intravitreal Bevacizumab and had an excellent response.

Neuroprotective effect of melatonin loaded in ethylcellulose nanoparticles applied topically in a retinal degeneration model in rabbits.

We are reporting for the first time the synthesis and application of an innovative nanometric system for the controlled topic release of melatonin in the retina. The ethylcellulose nanocapsules were characterized by diverse physicochemical techniques (scanning electron microscopy, zeta potential, hydrodynamic diameters) and an in vitro release study was done. A complete ex vivo and in vivo trans-corneal permeation and an irritation study were carried out with the new formulations in albino rabbits, to which a retinal degenerative model was induced. The results obtained demonstrate that the in vitro release of melatonin (1 mg/mL and 2 mg/mL) transported by nanocapsules is slower when compared to a solution of melatonin. Greater penetration of melatonin through the cornea was demonstrated by ex vivo and in vivo tests. This can be attributable to an enhanced neuroprotective effect of melatonin on retinal ganglion cells when it is included in ethylcellulose nanocapsules compared to a solution of melatonin. These outstanding findings add promising new perspectives to current knowledge about administrations using nano-technological tools in the treatment of neurodegenerative diseases at the ocular level.

A journey into the retina: Müller glia commanding survival and death.

Müller glial cells (MGCs) are known to participate actively in retinal development and to contribute to homoeostasis through many intracellular mechanisms. As there are no homologous cells in other neuronal tissues, it is certain that retinal health depends on MGCs. These macroglial cells are located at the centre of the columnar subunit and have a great ability to interact with neurons, astrocytes, microglia and endothelial cells in order to modulate different events. Several investigations have focused their attention on the role of MGCs in diabetic retinopathy, a progressive pathology where several insults coexist. As expected, data suggest that MGCs display different responses according to the severity of the stimulus, and therefore trigger distinct events throughout the course of the disease. Here, we describe physiological functions of MGCs and their participation in inflammation, gliosis, synthesis and secretion of trophic and antioxidant factors in the diabetic retina. We invite the reader to consider the protective/deleterious role of MGCs in the early and late stages of the disease. In the light of the results, we open up the discussion around and ask the question: Is it possible that the modulation of a single cell type could improve or even re-establish retinal function after an injury?

IGF-1R Regulates the Extracellular Level of Active MMP-2, Pathological Neovascularization, and Functionality in Retinas of OIR Mouse Model.

In ischemic proliferative diseases such as retinopathies, persistent hypoxia leads to the release of numerous neovascular factors that participate in the formation of abnormal vessels and eventually cause blindness. The upregulation and activation of metalloproteinases (MMP-2 and MMP-9) represent a final common pathway in this process. Although many regulators of the neovascular process have been identified, the complete role of the insulin-like growth factor 1 (IGF-1) and its receptor (IGF-1R) appears to be significantly more complex. In this study, we used an oxygen-induced retinopathy (OIR) mouse model as well as an in vitro model of hypoxia to study the role of MMP-2 derived from Müller glial cells (MGCs) and its relation with the IGF-1/IGF-1R system. We demonstrated that MMP-2 protein expression increased in P17 OIR mice, which coincided with the active phase of the neovascular process. Also, glutamine synthetase (GS)-positive cells were also positive for MMP-2, whereas IGF-1R was expressed by GFAP-positive cells, indicating that both proteins were expressed in MGCs. In addition, in the OIR model a single intravitreal injection of the IGF-1R blocking antibody (αIR3) administered at P12 effectively prevented pathologic neovascularization, accelerated physiological revascularization, and improved retinal functionality at P17. Finally, in MGC supernatants, the blocking antibody abolished the IGF-1 effect on active MMP-2 under normoxic and hypoxic conditions without affecting the extracellular levels of pro-MMP-2. These results demonstrate, for the first time, that the IGF-1/IGF-1R system regulates active MMP-2 levels in MGCs, thus contributing to MEC remodeling during the retinal neovascular process.

New Treatment Modalities for Neovascular Age-Related Macular Degeneration.

Age-related macular degeneration (AMD) is considered one of the main causes of severe vision loss in older adults. The neovascular form (nAMD) is an advanced stage, which is responsible for the most severe vision loss. Vascular endothelial growth factor (VEGF) is at present the main factor that leads to the development of a neovascular membrane and the increased leakage from the membrane to the retina. At present, anti-VEGF therapy is the only treatment that achieves vision gains in many patients and halts progression in most of them. VEGF blockade can be achieved with several molecules and various treatment regimens, which have been studied with excellent results. Unfortunately, real-world data has shown to be far less efficacious than clinical trials. This gap between clinical trials and real-world results is an unmet medical need that supports the necessity of new treatment modalities for nAMD. Of the various treatments being studied, anti-VEGFs of higher efficacy and longer durability are those more advanced in their development. Brolucizumab and abicipar pegol are 2 new anti-VEGF drugs that had positive results in phase 2 studies and are being tested in phase 3 trials at present. Other promising therapies are antiangiopoietin 2 molecules, which are in phase 2 development. At earlier stages of development but with promising results are squalamine, anti-VEGF-C and -D, and gene therapy. The future will give retina specialists a broad armamentarium with which patients may achieve high visual gains for the long term with a low treatment burden.

Galectin-1 expression imprints a neurovascular phenotype in proliferative retinopathies and delineates responses to anti-VEGF.

Neovascular retinopathies are leading causes of irreversible blindness. Although vascular endothelial growth factor (VEGF) inhibitors have been established as the mainstay of current treatment, clinical management of these diseases is still limited. As retinal impairment involves abnormal neovascularization and neuronal degeneration, we evaluated here the involvement of galectin-1 in vascular and non-vascular alterations associated with retinopathies, using the oxygen-induced retinopathy (OIR) model. Postnatal day 17 OIR mouse retinas showed the highest neovascular profile and exhibited neuro-glial injury as well as retinal functional loss, which persisted until P26 OIR. Concomitant to VEGF up-regulation, galectin-1 was highly expressed in P17 OIR retinas and it was mainly localized in neovascular tufts. In addition, OIR induced remodelling of cell surface glycophenotype leading to exposure of galectin-1-specific glycan epitopes. Whereas VEGF returned to baseline levels at P26, increased galectin-1 expression persisted until this time period. Remarkably, although anti-VEGF treatment in P17 OIR improved retinal vascularization, neither galectin-1 expression nor non-vascular and functional alterations were attenuated. However, this functional defect was partially prevented in galectin-1-deficient (Lgals1-/-) OIR mice, suggesting the importance of targeting both VEGF and galectin-1 as non-redundant independent pathways. Supporting the clinical relevance of these findings, we found increased levels of galectin-1 in aqueous humor from patients with proliferative diabetic retinopathy and neovascular glaucoma. Thus, using an OIR model and human samples, we identified a role for galectin-1 accompanying vascular and non-vascular retinal alterations in neovascular retinopathies.

IGF-1 Regulates the Extracellular Level of Active MMP-2 and Promotes Müller Glial Cell Motility.

PURPOSE: In ischemic proliferative retinopathies, Müller glial cells (MGCs) acquire migratory abilities. However, the mechanisms that regulate this migration remain poorly understood. In addition, proliferative disorders associated with enhanced activities of matrix metalloproteinases (MMPs) also involve insulin-like growth factor (IGF)-1 participation. Therefore, the main interest of this work was to investigate the IGF-1 effect on the extracellular proteolytic activity in MGCs. METHODS: Cell culture supernatants and cell lysates of the human MGC line MIO-M1 stimulated with IGF-1 were analyzed for MMP-2 by zymographic and Western blot analysis. The MGCs' motility was evaluated by scratch wound assay. The MMP-2, ß1-integrin, and focal adhesions were detected by confocal microscopy. The localization of active MMPs and actin cytoskeleton were evaluated by in situ zymography. RESULTS: The IGF-1 induced the activation of canonical signaling pathways through the IGF-1R phosphorylation. Culture supernatants showed a relative decrease in the active form of MMP-2, correlating with an increased accumulation of MMP-2 protein in the MGCs' lysate. The IGF-1 effect on MMP-2 was abolished by an IGF-1R blocking antibody, αIR3, as well as by the PI3-kinase inhibitor, LY294002. The IGF-1 increased the migratory capacity of MGCs, which was blocked by the GM6001 MMP inhibitor, LY294002 and αIR3. Finally, IGF-1 induced the intracellular distribution of MMP-2 toward cellular protrusions and the partial colocalization with ß1-integrin and phospo-focal adhesion kinase signals. Gelatinase activity was concentrated along F-actin filaments. CONCLUSIONS: Taken together, these data indicate that IGF-1, through its receptor activation, regulates MGCs' motility by a mechanism that involves the MMP-2 and PI3K signaling pathway.

Lens opacity based modelling of the age-related straylight increase.

This work studies ethnic and geographical differences in the age-related straylight increase by means of a stochastic model and unpublished lens opacity data of 559 residents of Villa Maria (Argentina), as well as data of 912 Indonesian subjects published previously by Husain et al. For both cohorts the prevalence of each type and grade of lens opacity was determined as a function of age, from which a stochastic model was derived capable of simulating the lens opacity prevalence for both populations. These simulated lens opacity data were then converted to estimated straylight by means of an equation derived from previously recorded data of 107 eyes with varying degrees of cataract. Based on these opacity templates 2500 random sets of subject age and lens opacity data were generated by the stochastic model for each dataset, from which estimated straylight could be calculated. For the Argentinian data the estimated straylight was found to closely resemble the published models for age-related straylight increase. For younger eyes the straylight variation of the model was the same as what was previously published (in both cases ±0.200logunits), which doubled in size for older eyes. For the Indonesian data, however, this age-related straylight increase was found to be fundamentally different from the published age model. This suggests that current normative curves for age-related straylight increase may not always be appropriate for non-European populations, and that the inter-individual straylight variations in young, healthy eyes may possibly be due to variations in lens opacities.

Rate of vision loss in neovascular age-related macular degeneration explored.

PURPOSE: To explore decline in visual acuity in patients with neovascular age-related macular degeneration (n-AMD) awaiting intravitreal bevacizumab or ranibizumab treatment following initial diagnosis and after disease reactivation. METHODS: Retrospective analysis of 74 treatment-naïve patients (84 eyes) in two centers in Córdoba, Argentina. The time between treatment indication and intravitreal injection, and the changes in BCVA produced during this delay were studied in both periods. A linear regression model to search the impact of time on progression visual impairment was conducted. RESULTS: In both periods, a significant reduction in vision occurred awaiting intravitreal injection. The longer the delay, the greater the vision loss (R2 = 0.55 p < 0.01) and the less improvement following treatment (Pearson coefficient -0.26). The result of the model shows that the change in vision as a function of initial delay were best described by a polynomic model with a mean loss of 5 letters in the first 3 weeks, a slowdown in the rate of change of VA, and a dependence of visual acuity at the moment of diagnosis . The loss of visual acuity after reactivation shows the same behavior as at the onset of the disease but independent of visual acuity prior to reactivation. CONCLUSION: Visual loss awaiting injection intravitreal anti-VEGF is clinically significant and with an asymptotic pattern, with early rapid loss of vision in both the onset of the disease and the reactivation. Initiation of anti-VEGF treatment must be undertaken urgently, as should retreatment of disease activation to reduce visual loss.

Long-term hypotony because of accidental break of a 23 g microcannula after transconjunctival sutureless vitrectomy.

PURPOSE: To report a case of long-lasting hypotony because of accidental break, with scleral tunnel entrapment, of a 23-gauge microcannula during transconjunctival sutureless vitrectomy. METHODS: Interventional case report. An 80-year-old Spanish woman who underwent 23-gauge transconjunctival sutureless vitrectomy presented at the postoperative ocular examination with irreversible, refractory low intraocular pressure of unknown cause. Two weeks after surgery, a piece of the microcannula was found at the inferotemporal sclerotomy site during a scheduled medical appointment. Surgical intervention was indicated to explore and remove the foreign body. RESULTS: The day after foreign body extraction, the patient's pressure rose to normal levels. However, her visual acuity did not improve until 3 weeks later. CONCLUSION: Transient postoperative hypotony is unsurprising after 23-gauge vitrectomy because of leakage of small-diameter open sclerotomies. However, when long-term low intraocular pressure fails to return to normal levels because of an unidentified condition, breaking of the microcannula piece with scleral tunnel entrapment may be contemplated.

Stenotrophomonas maltophilia endophthalmitis caused by surgical equipment contamination: an emerging nosocomial infection.

PURPOSE: We report three cases of Stenotrophomonas maltophilia endophthalmitis after uneventful extracapsular cataract extraction with intraocular lens implantation-related to surgical equipment contamination. CASE REPORT: All patients developed acute, culture-positive endophthalmitis in a period ranging from 2 to 13 days. Cultures from vitreous tap, as well as those obtained from the hand-piece of the irrigation-aspiration system, revealed S. maltophilia as the causing infectious agent. All patients received intravitreal antibiotic treatment as initial therapy, nevertheless, visual disturbance continued to be present, hence pars plana vitrectomy was required. CONCLUSION: Contamination of surgical-reusable equipment should be considered in addition to the well-known risk factors associated with development of endophthalmitis by S. maltophilia.

Accessibility as a conditioning factor in treatment for exudative age-related macular degeneration.

PURPOSE: Ranibizumab and bevacizumab coexist as the main therapeutic strategies for the treatment of neovascular age-related macular degeneration (NV-AMD). In Argentina, the access pathways to the drugs are different. Patients with different pathways and gatekeepers to access may experience different outcomes. The purpose of this work was to estimate the impact on therapeutic effects and visual outcome of the different accessibilities to NV-AMD treatment. 
 METHODS: A retrospective analysis of the charts of 78 patients with previously untreated exudative AMD, who were treated with ranibizumab or bevacizumab between January 2009 and December 2011, was conducted. The main outcomes measured included time delay and change in mean best-corrected visual acuity (BCVA) between diagnosis and treatment and mean BCVA change at 1-year follow-ups.
 RESULTS: The delay between diagnosis and treatment and decrease in visual acuity over this time was significantly higher for patients treated with ranibizumab. At 1 year after the initiation of treatment, BCVA had a mean increase from baseline of 0.11 letters in the bevacizumab group with a mean of 4.71 injections, compared with a decrease of 8.87 letters with a mean of 2.98 injections in the ranibizumab group.
 CONCLUSIONS: Access to treatment can be a key factor for success of therapy. Waiting times and availability of doses are crucial in the treatment of NV-AMD. Solving the problems related to delayed initiation of therapy and the difficulties in the maintenance phase are more important than define whether bevacizumab or ranibizumab is used.

Self-medication in ophthalmology: a questionnaire-based study in an Argentinean population.

PURPOSE: The aim of this study was to identify practices of self-medication in the treatment of ocular conditions and to identify a profile of patients who self-medicate. METHODS: We conducted a cross-sectional descriptive survey of patients, over the age of 17 years seen in our ophthalmology practice in Cordoba, Argentina. Self-medication was defined as the use of ophthalmic medicines which had not been prescribed by a health care specialist in the previous year. RESULTS: The sample included 379 subjects, 162 males (43%) and 217 females (57%); mean age 46.8 years. Prior to looking for medical attention in our institution, 97 patients (25.6%) reported self-medicating. The most frequently employed products included non-steroidal anti-inflammatory drops in combination with a vasoconstrictive agent (32%) followed by a combination of antibiotics and steroids (9%), however, 14% of patients did not remember the name or type of medication applied. A total of 31% of patients used drugs recommended by a pharmacist; 25% used drugs of their own choosing and 24% followed suggestions from a friend or family member. Only 12% of patients knew the drug's components and only 3% were aware of any possible side effects. There was no difference in behavior patterns related to educational level or age, however, there was a significant difference related to gender, with males misusing ophthalmic drops more frequently than women (P = 0.004). CONCLUSIONS: Patients commonly attempt to treat conditions that require ophthalmologic care by self-medicating with over-the-counter eye drops. Educational efforts to inform patients of the consequences of self-medication are necessary.

Delayed corneal epithelial healing after intravitreal bevacizumab: a clinical and experimental study.

PURPOSE: To report corneal epithelial defects (CEDs) and delayed epithelial healing after intravitreal bevacizumab (IVB) injection and to describe delayed corneal epithelial healing with topical administration of bevacizumab in an experimental rabbit model. METHODS: A retrospective chart review was performed on 850 eyes of 850 patients with neovascular eye disease and diabetic macular edema who had received 1.25 to 2.5 mg IVB. In the experimental arm of the study, photorefractive keratectomy was used to create a 3 mm CED in the right eyes of 18 New Zealand rabbits which were then randomized to three equal groups. All rabbits received topical antibiotics, additionally those in group A received topical bevacizumab and animals in group B were treated with topical corticosteroids. The rate of epithelial healing was assessed at different time points using slitlamp photography. RESULTS: In the clinical study, seven eyes of seven subjects developed CEDs the day after IVB injection. All of these eyes had preexisting corneal edema. The healing period ranged from 3 to 38 days (average 11 days) despite appropriate medical management. In the experimental study, topical bevacizumab and corticosteroids both significantly hindered corneal epithelial healing at 12 and 24 hours. CONCLUSION: Bevacizumab was demonstrated to cause CEDs in clinical settings. Moreover, corneal epithelial healing was delayed by topical application of bevacizumab, in the experimental model. These short-term results suggest that corneal edema may be considered as a risk factor for epithelial defects after IVB.

Perfluorocarbon liquid vitreous delamination and wide-angle viewing system in the management of complicated diabetic retinal detachment.

PURPOSE: The authors used perfluorocarbon liquid (PFCL) and a wide-angle viewing system (WAVS) to evaluate their efficacy on tractional and combined tractional/rhegmatogenous retinal detachment (RD) secondary to proliferative diabetic retinopathy (PDR). METHODS: In a prospective, noncomparative, interventional study, 76 consecutive cases of severe PDR with tractional and combined tractional/rhegmatogenous RD were submitted to vitrectomy en bloc excision technique using a WAVS and delamination with PFCL between July 1999 and December 2003. None of the patients had had previous retinal photocoagulation treatment. Preoperative characteristics, intraoperative findings, and procedures as well as postoperative results were recorded. Main outcome measures included visual acuity (VA) and rates of retinal reattachment and complications. RESULTS: After 1 to 4 years of follow-up (mean 34.3 months), the number of patients changed from 3 (3.95%) to 11 patients (14.47%) in the > or =20/40 VA range, from 12 (15.79%) to 7 (9.21%) in the 20/50 to 20/200 group, and from 61 (80.26%) to 58 (76.31%) in the < or =20/400 group, preoperatively and postoperatively, respectively. The mean final VA improved from 1.2 log-MAR before surgery to 0.89 after vitrectomy (p=0.001). This modified technique resulted in less bleeding during surgery, a better identification of intraocular structures, faster retinal reattachment, subretinal fluid reabsorption, and easier dissection of fibrovascular membranes, among other benefits. CONCLUSIONS: PFCL and WAVS appear to reduce intraoperative complication rates in the management of complicated cases of tractional and combined tractional/rhegmatogenous RD secondary to PDR. Retinal reattachment and functional vision rates improved after this technique.

Effect of retinal laser photocoagulation on the activity of metalloproteinases and the alpha(2)-macroglobulin proteolytic state in the vitreous of eyes with proliferative diabetic retinopathy.

Panretinal photocoagulation (PRP) reduces the incidence of severe visual loss in proliferative diabetic retinopathy (PDR). The aim of the study was to determine the effect of PRP on the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9, and also on the alpha(2)-Macroglobulin (alpha(2)M) proteolytic state in the vitreous of eyes with PDR. Vitreous samples were obtained from patients undergoing vitrectomy for the treatment of retinal diseases: 17 with PDR and eight with idiopathic macular hole (MH). Qualitative evaluation of the MMP-2 and MMP-9 activation status was performed by gelatin zymography and quantitative assay was carried out for vitreous total protein content and alpha(2)M. The proteolytic state of alpha(2)M was evaluated by Western blotting. Although all vitreous samples contained proMMP-2, increased proMMP-9 and active MMP-9 were detected in PDR samples without PRP. In addition, after PRP the proMMP-9 activity was significantly decreased, whereas the proMMP-2 activity was not affected. Enhanced total protein and alpha(2)M concentrations were observed in all vitreous samples from PDR patients with and without previous PRP compared with samples from patients with MH. However, a differential proteolytic state of alpha(2)M, expressed as 180/85-90kDa ratio, was detected among PDR patients with and without PRP treatment. Whereas a low 180/85-90kDa ratio of alpha(2)M in vitreous of PDR patients without PRP was observed, a high proportion of 180kDa subunit was principally detected in PDR with PRP. These results demonstrate that PDR occurs with an enhanced activity of MMP-9 and activation of alpha(2)M by proteinases, which is reversed after PRP. In addition, we suggest that alpha(2)M plays a key role in the control and regulation of the ocular neovascularization involved in the pathogenesis of ischemic retinal diseases such as PDR.