Rupert W. Strauss

Angiopoietin 2 expression in the retina: upregulation during physiologic and pathologic neovascularization

Vascular development in the embryo requires coordinated signaling through several endothelial cell‐specific receptors; however, it is not known whether this is also required later during retinal vascular development or as part of retinal neovascularization in adults. The Tie2 receptor has been implicated in stabilization and maturation of vessels through action of an agonist ligand, angiopoietin 1 (Ang1) and an antagonistic ligand, Ang2. In this study, we have demonstrated that ang2 mRNA levels are increased in the retina during development of the deep retinal capillaries by angiogenesis and during pathologic angiogenesis in a model of ischemic retinopathy. Mice with hemizygous disruption of the ang2 gene by insertion of a promoterless β‐galactosidase (βgal) gene behind the ang2 promoter, show constitutive βgal staining primarily in cells along the outer border of the inner nuclear layer identified as horizontal cells by colocalization of calbindin. During development of the deep capillary bed or retinal neovascularization, other cells in the inner nuclear layer and ganglion cell layer, in regions of neovascularization, stain for βgal. Thus, there is temporal and spatial correlation of Ang2 expression with developmental and pathologic angiogenesis in the retina, suggesting that it may play a role. J. Cell. Physiol. 184:275–284, 2000.

Long-term effect of intravitreal bevacizumab (avastin) in patients with chronic diffuse diabetic macular edema.

Purpose: To evaluate the long-term efficacy of bevacizumab for the treatment of chronic diffuse diabetic macular edema after various previous treatments. Methods: A total of 126 patients (mean age: 66 years) with chronic diffuse diabetic macular edema were consecutively incorporated in this prospective, noncomparative case series. Inclusion was performed independently from the size of edema, retinal thickness, visual acuity (VA), age, metabolic control, type of diabetes, or type of previous treatments. The patients underwent a complete eye examination including best-corrected VA with ETDRS charts, slit lamp examination, intraocular pressure measurement, stereoscopic biomicroscopy of the macula, retinal thickness measurement using optical coherence tomography (OCT), fluorescein angiography, and fundus photography. All patients were treated with repeated intravitreal injections of bevacizumab (1.25 mg). Patients were observed in intervals of 4–12 weeks for a period of up to 6–12 months. Results: All patients had received various previous treatments such as laser treatment (62% focal laser treatment, 38% panretinal laser treatment), vitrectomy (11%), or intravitreal injection of triamcinolone (41%). All patients completed 6 months and 59 patients (47%) completed 12 months of follow-up; within this period 48% had received at least three intravitreal injections of bevacizumab. Mean diameter of foveal avascular zone was 858 ± 341 &mgr;m. At baseline mean VA was 40.3 ETDRS letters (0.82 logMAR Snellen VA) and mean central retinal thickness on OCT was 463 &mgr;m. Throughout follow-up VA changes were not significant with a mean change of −1.6 ETDRS letters after 6 months, but significant with +5.1 ETDRS letters after 12 months. Mean central retinal thickness (OCT) decreased to 374 &mgr;m after 6 months (P < 0.001) and to 357 &mgr;m after 12 months (P < 0.001). Changes of retinal thickness and visual acuity did not correlate. No other factors investigated, such as age, central retinal thickness, or previous treatments, were predictive for a change of VA. Macular ischemia was not exacerbated as a result of the treatment. Conclusion: Even in cases with chronic diffuse ischemic diabetic macular edema, a long-term decrease of central retinal thickness can be observed following repeated intravitreal injections of bevacizumab. In these patients, mean decrease in retinal thickness is aligned with a gain in mean VA. Treatment with bevacizumab at an earlier stage of diabetic macular edema without ischemia may be associated with an even better functional outcome.

Intravitreal bevacizumab injections for treatment of central retinal vein occlusion: six-month results of a prospective trial.

Purpose: To evaluate the effect of intravitreal bevacizumab (Avastin; Genentech, Inc., South San Francisco, CA) injections on visual acuity and foveal retinal thickness in patients with central retinal vein occlusion (CRVO). Methods: In this prospective, noncomparative, consecutive, interventional case series, 46 patients received repeated intravitreal injections (1.25 mg) of bevacizumab. Main outcome measures were visual acuity (Snellen and ETDRS charts) and optical coherence tomography measurements in a 6-month follow-up period. Results: Mean visual acuity improved from 20/250 at baseline to 20/80 at the 6-month follow-up (P < 0.001). ETDRS chart findings revealed a mean letter gain ±SD from baseline to 6 months of 13.9 ± 14.4 letters. Mean central retinal thickness ±SD decreased from 535 ± 148 &mgr;m at baseline to 323 ± 116 &mgr;m at the 6-month follow-up. Ischemic CRVO was associated with significantly lower visual acuity than nonischemic CRVO (P < 0.001). However, visual acuity gain was similar in both groups. Independent of duration of symptoms, CRVO was associated with a similar gain in visual acuity. Conclusion: Intravitreal injection of bevacizumab appears to be a new treatment option for patients with macular edema secondary to CRVO.

Emerging therapies for inherited retinal degeneration

This Review discusses current and emerging therapies for treating inherited retinal degeneration. Inherited retinal degenerative diseases, a genetically and phenotypically heterogeneous group of disorders, affect the function of photoreceptor cells and are among the leading causes of blindness. Recent advances in molecular genetics and cell biology are elucidating the pathophysiological mechanisms underlying these disorders and are helping to identify new therapeutic approaches, such as gene therapy, stem cell therapy, and optogenetics. Several of these approaches have entered the clinical phase of development. Artificial replacement of dying photoreceptor cells using retinal prostheses has received regulatory approval. Precise retinal imaging and testing of visual function are facilitating more efficient clinical trial design. In individual patients, disease stage will determine whether the therapeutic strategy should comprise photoreceptor cell rescue to delay or arrest vision loss or retinal replacement for vision restoration.

The Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) Studies: Design and Baseline Characteristics: ProgStar Report No. 1

PURPOSE To describe the design and baseline characteristics of patients enrolled into 2 natural history studies of Stargardt disease (STGD1). DESIGN Multicenter retrospective and prospective cohort studies. PARTICIPANTS Three hundred sixty-five unique patients aged 6 years and older at baseline harboring disease-causing variants in the ABCA4 gene and with specified ocular lesions were enrolled from 9 centers in the United States and Europe. METHODS In the retrospective study, patients contributed medical record data from at least 2 and up to 4 visits for at least 1 examination modality: fundus autofluorescence (FAF), spectral-domain (SD) optical coherence tomography (SD OCT), and/or microperimetry (MP). The total observational period was at least 2 years and up to 5 years between single visits. Demographic and visual acuity (VA) data also were obtained. In the prospective study, eligible patients were examined at baseline using a standard protocol, with 6-month follow-up visits planned for a 2-year period for serial Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected VA, SD OCT, FAF, and MP. MAIN OUTCOME MEASURES Design and rationale of a multicenter study to determine the progression of STGD1 in 2 large retrospective and prospective international cohorts. Detailed baseline characteristics of both cohorts are presented, including demographics, and structural and functional retinal metrics. RESULTS Into the retrospective study, 251 patients (458 eyes) were enrolled; mean follow-up ± standard deviation was 3.9±1.6 years. At baseline, 36% had no or mild VA loss, and 47% of the study eyes had areas of definitely decreased autofluorescence (DDAF) with an average lesion area of 2.5±2.9 mm(2) (range, 0.02-16.03 mm(2)). Two hundred fifty-nine patients (489 eyes) were enrolled in the prospective study. At baseline, 20% had no or mild VA loss, and 64% had areas of DDAF with an average lesion area of 4.0±4.4 mm(2) (range, 0.03-24.24 mm(2)). The mean retinal sensitivity with MP was 10.8±5.0 dB. CONCLUSIONS The ProgStar cohorts have baseline characteristics that encompass a wide range of disease severity and are expected to provide valuable data on progression based on serial quantitative measurements derived from multiple methods, which will be critical to the design of planned clinical trials.

Is There Excess Oxidative Stress and Damage in Eyes of Patients with Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a group of diseases in which a mutation in one of the large variety of genes causes death of rod photoreceptors. After rods die, cone photoreceptors gradually die resulting in constriction of visual fields and eventual blindness in many patients. Studies in animal models of RP have demonstrated that oxidative damage is a major contributor to cone cell death. In this study, we extended those findings to patients with RP, because compared to control patients, those with RP showed significant reduction in the reduced to oxidized glutathione (GSH/GSSG) ratio in aqueous humor and a significant increase in aqueous protein carbonyl content. In contrast, there was no significant decrease in the serum GSH/GSSG ratio or increase in carbonyl content of serum proteins. These data indicate that patients with RP have ocular oxidative stress and damage in the absence of manifestations of systemic oxidative stress and/or damage indicating that demonstrations of oxidative damage-induced cone cell death in animal models of RP may translate to human RP. These observations lead to the hypothesis that potent antioxidants will promote cone survival and function in patients with RP and that the aqueous GSH/GSSG ratio and carbonyl content on proteins may provide useful biomarkers. Antioxid. Redox Signal. 23, 643-648.

Vitreoretinal surgery using bromphenol blue as a vital stain: evaluation of staining characteristics in humans

Objective: To evaluate the staining characteristics of bromphenol blue used during vitreoretinal surgery in humans. Patients and methods: 13 patients with epiretinal membranes were included. Before and after surgery a complete clinical examination including best corrected visual acuity, funduscopy, fluorescein angiography, OCT (Stratus), Goldmann perimetry and multifocal ERG as well as photography of the macular area was performed. Bromphenol blue was used in concentrations of 0.2% in most patients. Removed epiretinal tissue was evaluated using electron microscopy. Results: Using dye concentrations of 0.2% a good demarcation of epiretinal membranes was seen in 11/13 patients. Staining of vitreous remnants at the vitreous base was seen in all patients. No dye-related adverse events were seen during follow-up in the functional tests (VA, ERG, perimetry) performed. Histological evaluation of epiretinal membranes showed unremarkable aspects of epiretinal cellular layers and unremarkable retinal surface of the internal limiting membrane (ILM). Conclusion: Bromphenol blue appears to be a very helpful and safe tool in posterior segment surgery. The staining characteristics need to be further evaluated in prospective study settings and larger numbers of patients.

COMPARISON OF MANUAL AND SEMIAUTOMATED FUNDUS AUTOFLUORESCENCE ANALYSIS OF MACULAR ATROPHY IN STARGARDT DISEASE PHENOTYPE.

Purpose: To evaluate manual and semiautomated grading techniques for assessing decreased fundus autofluorescence (DAF) in patients with Stargardt disease phenotype. Methods: Certified reading center graders performed manual and semiautomated (region finder—based) grading of confocal scanning laser ophthalmoscopy (cSLO) fundus autofluorescence (FAF) images for 41 eyes of 22 patients. Lesion types were defined based on the black level and sharpness of the border: definite decreased autofluorescence (DDAF), well, and poorly demarcated questionably decreased autofluorescence (WDQDAF, PDQDAF). Agreement in grading between the two methods and inter- and intra-grader agreement was assessed by kappa coefficients (&kgr;) and intraclass correlation coefficients (ICC). Results: The mean ± standard deviation (SD) area was 3.07 ± 3.02 mm2 for DDAF (n = 31), 1.53 ± 1.52 mm2 for WDQDAF (n = 9), and 6.94 ± 10.06 mm2 for PDQDAF (n = 17). The mean ± SD absolute difference in area between manual and semiautomated grading was 0.26 ± 0.28 mm2 for DDAF, 0.20 ± 0.26 mm2 for WDQDAF, and 4.05 ± 8.32 mm2 for PDQDAF. The ICC (95% confidence interval) for method comparison was 0.992 (0.984–0.996) for DDAF, 0.976 (0.922–0.993) for WDQDAF, and 0.648 (0.306–0.842) for PDQDAF. Inter- and intra-grader agreement in manual and semiautomated quantitative grading was better for DDAF (0.981–0.996) and WDQDAF (0.995–0.999) than for PDQDAF (0.715–0.993). Conclusion: Manual and semiautomated grading methods showed similar levels of reproducibility for assessing areas of decreased autofluorescence in patients with Stargardt disease phenotype. Excellent agreement and reproducibility were observed for well demarcated lesions.

Assessment of estimated retinal atrophy progression in Stargardt macular dystrophy using spectral- domain optical coherence tomography

Aims To estimate disease progression based on analysis of macular volume measured by spectral-domain optical coherence tomography (SD-OCT) in patients affected by Stargardt macular dystrophy (STGD1) and to evaluate the influence of software errors on these measurements. Methods 58 eyes of 29 STGD1 patients were included. Numbers and types of algorithm errors were recorded and manually corrected. In a subgroup of 36 eyes of 18 patients with at least two examinations over time, total macular volume (TMV) and volumes of all nine Early Treatment of Diabetic Retinopathy Study (ETDRS) subfields were obtained. Random effects models were used to estimate the rate of change per year for the population, and empirical Bayes slopes were used to estimate yearly decline in TMV for individual eyes. Results 6958 single B-scans from 190 macular cube scans were analysed. 2360 (33.9%) showed algorithm errors. Mean observation period for follow-up data was 15 months (range 3–40). The median (IQR) change in TMV using the empirical Bayes estimates for the individual eyes was −0.103 (−0.145, −0.059) mm3 per year. The mean (±SD) TMV was 6.321±1.000 mm3 at baseline, and rate of decline was −0.118 mm3 per year (p=0.003). Yearly mean volume change was −0.004 mm3 in the central subfield (mean baseline=0.128 mm3), −0.032 mm3 in the inner (mean baseline=1.484 mm3) and −0.079 mm3 in the outer ETDRS subfields (mean baseline=5.206 mm3). Conclusions SD-OCT measurements allow monitoring the decline in retinal volume in STGD1; however, they require significant manual correction of software errors.

Comparison of Short-Wavelength Reduced-Illuminance and Conventional Autofluorescence Imaging in Stargardt Macular Dystrophy

Purpose To compare grading results between short-wavelength reduced-illuminance and conventional autofluorescence imaging in Stargardt macular dystrophy. Design Reliability study. Methods setting: Moorfields Eye Hospital, London (United Kingdom). patients: Eighteen patients (18 eyes) with Stargardt macular dystrophy. observation procedures: A series of 3 fundus autofluorescence images using 3 different acquisition parameters on a custom-patched device were obtained: (1) 25% laser power and total sensitivity 87; (2) 25% laser power and freely adjusted sensitivity; and (3) 100% laser power and freely adjusted total sensitivity (conventional). The total area of 2 hypoautofluorescent lesion types (definitely decreased autofluorescence and poorly demarcated questionably decreased autofluorescence) was measured. main outcome measures: Agreement in grading between the 3 imaging methods was assessed by kappa coefficients (κ) and intraclass correlation coefficients. Results The mean ± standard deviation area for images acquired with 25% laser power and freely adjusted total sensitivity was 2.04 ± 1.87 mm2 for definitely decreased autofluorescence (n = 15) and 1.86 ± 2.14 mm2 for poorly demarcated questionably decreased autofluorescence (n = 12). The intraclass correlation coefficient (95% confidence interval) was 0.964 (0.929, 0.999) for definitely decreased autofluorescence and 0.268 (0.000, 0.730) for poorly demarcated questionably decreased autofluorescence. Conclusions Short-wavelength reduced-illuminance and conventional fundus autofluorescence imaging showed good concordance in assessing areas of definitely decreased autofluorescence. However, there was significantly higher variability between imaging modalities for assessing areas of poorly demarcated questionably decreased autofluorescence.