Marc D. de Smet

The International Vitreomacular Traction Study Group Classification of Vitreomacular Adhesion, Traction, and Macular Hole

OBJECTIVE The International Vitreomacular Traction Study (IVTS) Group was convened to develop an optical coherence tomography (OCT)-based anatomic classification system for diseases of the vitreomacular interface (VMI). DESIGN The IVTS applied their clinical experience, after reviewing the relevant literature, to support the development of a strictly anatomic OCT-based classification system. PARTICIPANTS A panel of vitreoretinal disease experts was the foundation of the International Classification System. METHODS Before the meeting, panel participants were asked to review 11 articles and to complete 3 questionnaires. The articles were preselected based on searches for comprehensive reviews covering diseases of the VMI. Responses to questionnaires and the groups opinions on definitions specified in the literature were used to guide the discussion. MAIN OUTCOME MEASURES Optical coherence tomography-based anatomic definitions and classification of vitreomacular adhesion, vitreomacular traction (VMT), and macular hole. RESULTS Vitreomacular adhesion is defined as perifoveal vitreous separation with remaining vitreomacular attachment and unperturbed foveal morphologic features. It is an OCT finding that is almost always the result of normal vitreous aging, which may lead to pathologic conditions. Vitreomacular traction is characterized by anomalous posterior vitreous detachment accompanied by anatomic distortion of the fovea, which may include pseudocysts, macular schisis, cystoid macular edema, and subretinal fluid. Vitreomacular traction can be subclassified by the diameter of vitreous attachment to the macular surface as measured by OCT, with attachment of 1500 μm or less defined as focal and attachment of more than 1500 μm as broad. When associated with other macular disease, VMT is classified as concurrent. Full-thickness macular hole (FTMH) is defined as a foveal lesion with interruption of all retinal layers from the internal limiting membrane to the retinal pigment epithelium. Full-thickness macular hole is primary if caused by vitreous traction or secondary if directly the result of pathologic characteristics other than VMT. Full-thickness macular hole is subclassified by size of the hole as determined by OCT and the presence or absence of VMT. CONCLUSIONS This classification system will support systematic diagnosis and management by creating a clinically applicable system that is predictive of therapeutic outcomes and is useful for the execution and analysis of clinical studies.

A randomized, controlled trial of foscarnet in the treatment of cytomegalovirus retinitis in patients with AIDS

OBJECTIVE To evaluate foscarnet sodium in treating cytomegalovirus retinitis in patients with AIDS. PATIENTS Twenty-four previously untreated persons with AIDS and cytomegalovirus retinitis who were at low risk for loss of their visual acuity. INTERVENTION PATIENTS were randomly assigned to receive either no therapy (delayed treatment, control group) or immediate treatment with intravenous foscarnet at a dose of 60 mg/kg body weight three times a day for 3 weeks (induction regimen) followed by a maintenance regimen of 90 mg/kg once a day. MEASUREMENTS PATIENTS were examined weekly until they reached the primary clinical end point, defined as progression of their retinitis border by 750 microns or the development of a new retinal lesion due to cytomegalovirus. Progression was evaluated using retinal photographs by masked readers. Secondary evaluations included changes in visual acuity, cytomegalovirus shedding in the blood and urine, serum levels of human immunodeficiency virus type 1 (HIV-1) p24 antigen, and total CD4 T lymphocyte counts. RESULTS The mean time to progression of retinitis was 3.2 weeks in the control group (n = 11) compared with 13.3 weeks in the treatment group (n = 13) (P less than 0.001). Nine of 13 patients in the treatment group had positive blood cultures for cytomegalovirus at entry and all nine cleared their blood of cytomegalovirus by the end of the induction period (P = 0.004) compared with one of six patients in the control group. No reductions in p24 levels were seen in the control patients compared with a reduction of more than 50% in p24 levels for all four patients on treatment for whom follow-up levels were available. The main adverse effects of foscarnet treatment were seizures (2 of 13 patients), hypomagnesemia (9 of 13), hypocalcemia (11 of 13), and elevations in serum creatinine above 176.8 mumol/L (2.0 mg/dL) (3 of 13). The control patients received an average of 0.2 units of blood per week compared with an average of 0.6 units of blood per week for the patients on treatment. CONCLUSIONS The administration of foscarnet decreases the rate of progression of cytomegalovirus retinitis in persons with AIDS. Its judicious use is likely to prevent loss of vision in these patients. In this study, however, there was little change in visual acuity in patients in either the immediate or delayed treatment group because only patients with non-sight-threatening disease were selected.

Recent developments in optical coherence tomography for imaging the retina

Optical coherence tomography (OCT) was introduced in ophthalmology a decade ago. Within a few years in vivo imaging of the healthy retina and optic nerve head and of retinal diseases was a fact. In particular the ease with which these images can be acquired considerably changed the diagnostic strategy used by ophthalmologists. The OCT technique currently available in clinical practice is referred to as time-domain OCT, because the depth information of the retina is acquired as a sequence of samples, over time. This can be done either in longitudinal cross-sections perpendicular to, or in the coronal plane parallel to the retinal surface. Only recently, major advances have been made as to image resolution with the introduction of ultrahigh resolution OCT and in imaging speed, signal-to-noise ratio and sensitivity with the introduction of spectral-domain OCT. Functional OCT is the next frontier in OCT imaging. For example, polarization-sensitive OCT uses the birefringent characteristics of the retinal nerve fibre layer to better assess its thickness. Blood flow information from retinal vessels as well as the oxygenation state of retinal tissue can be extracted from the OCT signal. Very promising are the developments in contrast-enhanced molecular optical imaging, for example with the use of scattering tuneable nanoparticles targeted at specific tissue or cell structures. This review will provide an overview of these most recent developments in the field of OCT imaging focussing on applications for the retina.

Cellular Immune Responses of Patients with Uveitis to Retinal Antigens and Their Fragments

Of two patient populations totaling 82 patients, one in the United States and the other in Japan, we studied the cellular immune responses against S-antigen and interphotoreceptor retinoid binding protein as well as to fragments of each antigen. Behçets disease, birdshot retinochoroidopathy, pars planitis, ocular sarcoid, sympathetic ophthalmia, and the Vogt-Koyanagi-Harada syndrome were diagnosed in these patients. The response profile of both antigens paralleled each other. This profile was more commonly seen in patients suffering from diseases affecting the retina. Responders reacting to both antigens or to several fragments of an antigen were present. This pattern of response was seen in 26 of the patients tested. Patients with uveitis appeared able to recognize several autoantigens. This might be a consequence of the breakdown of the blood-retinal barrier and may help perpetuate the inflammatory process. Several patients were capable of responding to more than one epitope of the same antigen, which indicates that there are major differences between the experimental model and human autoimmune diseases in the response to autoantigens. Both of these findings may to help develop new immunotherapeutic strategies in the treatment of uveitis.

Understanding uveitis: the impact of research on visual outcomes.

The term uveitis encompasses a very diverse group of inflammatory ocular diseases that cause a significant burden of legal and economic blindness. Indeed, the socioeconomic impact of uveitis is at least as significant as that of diabetic retinopathy and, in the majority of cases, those affected are young individuals of working age. Significant progress has been made in our understanding of the mechanisms underlying the inflammatory process through the use of animal models, but correlation with human disease has proved elusive and many scientific approaches which appear highly effective in animal models prove to be less effective in patients. Nevertheless, effective, targeted treatments are needed in uveitis as current treatment is based on corticosteroids and immunosuppressive drugs whose usefulness is limited by their many side-effects. The aims of this review are to summarize the state of clinical research in uveitis, to identify gaps in our knowledge, and to propose new opportunities and methodologies for future developments in all aspects of uveitis research, including epidemiology, economic impact analysis, diagnosis, therapeutics, and clinical study design. Optimal patient management and efficient drug development depend on validated structured tools, such as those that have helped to drive a rapid acceleration in the means and methods available to assess and treat patients with rheumatoid arthritis and cancer. Uveitis care should witness a similar boom as the issues discussed are resolved.

The angio-fibrotic switch of VEGF and CTGF in proliferative diabetic retinopathy.

Background In proliferative diabetic retinopathy (PDR), vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF) cause blindness by neovascularization and subsequent fibrosis, but their relative contribution to both processes is unknown. We hypothesize that the balance between levels of pro-angiogenic VEGF and pro-fibrotic CTGF regulates angiogenesis, the angio-fibrotic switch, and the resulting fibrosis and scarring. Methods/Principal Findings VEGF and CTGF were measured by ELISA in 68 vitreous samples of patients with proliferative DR (PDR, N = 32), macular hole (N = 13) or macular pucker (N = 23) and were related to clinical data, including degree of intra-ocular neovascularization and fibrosis. In addition, clinical cases of PDR (n = 4) were studied before and after pan-retinal photocoagulation and intra-vitreal injections with bevacizumab, an antibody against VEGF. Neovascularization and fibrosis in various degrees occurred almost exclusively in PDR patients. In PDR patients, vitreous CTGF levels were significantly associated with degree of fibrosis and with VEGF levels, but not with neovascularization, whereas VEGF levels were associated only with neovascularization. The ratio of CTGF and VEGF was the strongest predictor of degree of fibrosis. As predicted by these findings, patients with PDR demonstrated a temporary increase in intra-ocular fibrosis after anti-VEGF treatment or laser treatment. Conclusions/Significance CTGF is primarily a pro-fibrotic factor in the eye, and a shift in the balance between CTGF and VEGF is associated with the switch from angiogenesis to fibrosis in proliferative retinopathy.

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.

Intravitreal injection of microplasmin for treatment of vitreomacular adhesion: results of a prospective, randomized, sham-controlled phase II trial (the MIVI-IIT trial).

Purpose: Vitreomacular adhesion causing vitreomacular traction is a common indication for vitrectomy. It may be avoided by using enzymatic vitreolysis. The MIVI-IIT (traction) study evaluated the ability of a single or repeated injection of microplasmin to release vitreomacular traction. Methods: This randomized, double-masked, Phase II trial with control sham injection enrolled 60 patients. Patients in each of the 4 cohorts were randomized (4:1) to active treatment or sham injection. In the first 3 cohorts, increasing doses of microplasmin (75, 125, and 175 μg) were administered. In the fourth cohort, an initial injection of 125 μg microplasmin or sham was administered followed 1 month later by an injection of 125 μg microplasmin if no release of adhesion occurred. A third dose was injected 4 weeks later if there was still no release of adhesion. Results: Within 28 days of sham, 75, 125, and 175 μg microplasmin administration, nonsurgical resolution of vitreomacular adhesion was observed in 8, 25, 44, and 27% of the patients, respectively. When the 125 μg dose was repeated up to 3 times, adhesion release was observed in 58% of patients 28 days after the final injection. Conclusion: These results provide support for the potential of microplasmin as a nonsurgical treatment for vitreomacular adhesion.

Regulation of Ocular Inflammation — What Experimental and Human Studies have Taught Us

Study of models of ocular autoimmunity and of autoimmune uveitis in humans has lead to a shift in the perceived nature of immune privilege from one based on anatomical isolation of the eye to a more dynamic, active process of immune tolerance. Using a variety of available models, the basis for this dynamic process of immune regulation is reviewed. The protective role of humoral immunity, the co-stimulatory function of B cells in EAU as well as the influence of cytokines within the inflammatory cascade are outlined. Modulation of the immune response and in particular the possible role of macrophages is explored. Within the current paradyme, a major effector cell is the CD4+ lymphocyte. Its maturation into a Th1 or Th2 phenotype process appears dependent on a number of exogenous factors, which while genetically determined can be manipulated prior to disease onset. Activation of CD4+ cells is dependent on presentation of immunoreactive peptide fragments. These fragments are well characterized in the Lewis rat for S-Ag and interphotoreceptor retinoid binding protein (IRBP). Mapping of the immunoreactivity to S-Ag has been recently completed in uveitis patients. An overlap with certain determinants identified in experimental models has been observed, in at least 2 disease entities. However, the response profile is not fixed in time and is subject to determinant spread. Future studies will be aimed at identifying with more detail immunologic triggers of inflammation in patients, and at better defining the interplay between effector and regulatory pathways both in the eye and in the systemic circulation.

Iatrogenic retinal breaks in 25-gauge macular surgery.

PURPOSE To describe the incidence and characteristics of iatrogenic retinal breaks in 25-gauge macular surgery. DESIGN Retrospective, noncomparative, interventional case series. METHODS We included 177 consecutive operations in 171 patients who underwent 25-gauge vitrectomy for idiopathic macular pucker or idiopathic macular hole. Main outcome measures were the incidence of breaks related to the sclerotomies, the incidence of breaks occurring elsewhere, the incidence of lesions suspicious for traction, the location of identified breaks, and intraoperative induction of posterior vitreous detachment (PVD). RESULTS Retinal breaks occurred in 15.8% of operations. In 6.2%, breaks were related to the sclerotomies, and in 10.7%, breaks were found elsewhere. In 8.5% of eyes, only lesions suspicious for traction were detected. Breaks or suspicious lesions were treated with external cryocoagulation in a total of 24.3% of cases. A statistically significant relation between PVD induction and presence of breaks elsewhere was identified. No correlation with lens status, initial diagnosis, or preoperative refraction was found. Retinal detachment occurred in 1.7% of cases. CONCLUSIONS We report an incidence of retinal breaks that is higher than previously found for 20- or 25-gauge surgery. Despite the high incidence of breaks, the incidence of postoperative retinal detachment was low. A specific characteristic was the relatively high incidence of breaks elsewhere and their relation to PVD induction. Our findings underscore the importance of scrupulous full 360-degree internal search at the end of each procedure to identify and treat all breaks and suspicious lesions optimally.