Polychromatic angiography for the assessment of VEGF-induced BRB dysfunction in the rabbit retina.

PURPOSE: To determine the utility of polychromatic angiography (PCA) in the assessment of VEGF-induced blood retinal barrier (BRB) dysfunction in rabbits. METHODS: Twenty-six eyes of 24 Dutch Belted rabbits were injected intravitreally with 1.25 µg (group A, n = 5), 10 µg (group C, n = 7), or 4 µg (group B, n = 6; group D, n = 4; and group E, n = 4) of VEGF on day 0. Groups D and E were also injected intravitreally with 1.25 µg and 12.5 µg bevacizumab, respectively, on day 2. On days 0, 2, 4, 7, 11, and 14, PCA was performed using a contrast agent mixture composed of fluorescein sodium, indocyanine green, PCM102, and PCM107 and imaged with a modified fundus camera. PCA scores were based on detected leaking fluorophores. RESULTS: On day 7, there was a statistically significant difference between PCA scores of group A (0.6 ± 0.89) and both groups B (2.67 ± 1.37, P = 0.0154) and C (3.33 ± 0.52, P = 0.00085). There was also a statistically significant difference between groups B and E (PCA score 0.75 ± 0.96, P = 0.032) on day 7. On day 11, there was statistically significant difference between group C (1.80 ± 1.1) and both groups A (0, P = 0.021) and B (0.33 ± 0.52, P = 0.037). CONCLUSIONS: A differential response to both increasing VEGF dose and administration of bevacizumab could be discerned using the PCA. PCA allowed stratification of VEGF-induced BRB dysfunction and inhibitory effects of bevacizumab therapy in the rabbit retina.

Electroretinography and microperimetry as noninvasive diagnostic tools for cilioretinal artery occlusion.

PURPOSE: To report a case of cilioretinal artery occlusion with normal fluorescein angiography findings that was evaluated by electroretinography (ERG) and microperimetry. METHODS: A 64-year-old-man presented with an oval paracentral scotoma in the temporal field of the left eye that became more evident after cataract surgery. Fundus photography, fluorescein angiography, ERG, multifocal ERG, and microperimetry were performed. RESULTS: Multifocal ERG showed decreased signal amplitudes in areas corresponding to areas with a visual defect as detected by microperimetry. Pattern ERG also showed a defect in the P50 component. Findings of fundus photography, fluorescein angiography, and full-field ERG were within normal limits. CONCLUSION: This case demonstrates the possibility of using ERG and microperimetry as noninvasive tools in the diagnosis of cilioretinal artery occlusion.

Functional and structural measurements for the assessment of internal limiting membrane peeling in idiopathic macular pucker.

OBJECTIVE: To investigate the role of structural and functional measurements in the assessment of internal limiting membrane (ILM) peeling for the treatment of eyes with macular pucker. METHODS: Ten patients with macular pucker who underwent pars plana vitrectomy with ILM peeling were studied prospectively. Visual acuity measurement, standard automated achromatic perimetry, multifocal electroretinography (mfERG), and optical coherence tomography (OCT) were performed before and 3 months after surgery. Four surgical samples obtained from similar patients were analyzed with electron microscopy. RESULTS: Three months after surgery, mean visual acuity +/- SD was significantly improved from 0.4 +/- 0.11 logMAR to 0.19 +/- 0.13 logMAR (P < or = 0.002), and mean central retinal thickness +/- SD was significantly decreased 428 +/- 73 microm to 326 +/- 34 microm (P < or = 0.002). The mfERG response amplitudes were slightly decreased in eight patients, and five of these patients also had asymptomatic decreases in visual field sensitivity. The electron micrographs revealed segments of Müller cell footplates on the retinal side of the ILM in all four specimens. CONCLUSION: In this study, the use of mfERG, OCT, and standard automated achromatic perimetry showed changes in macular function and structure postoperatively. These measures of visual function and structure allow for better evaluation of the surgical outcome and understanding of the changes that may occur after ILM peeling.

Measurement of the actual dose of triamcinolone acetonide delivered by common techniques of intravitreal injection.

PURPOSE: To measure the actual dose of triamcinolone acetonide (TA) delivered during intravitreal injection performed by several common techniques. DESIGN: Experimental study. METHODS: A 0.1-ml, 40-mg vial of TA (Kenalog-40; Bristol-Myers-Squibb, Peapack, New Jersey, USA) was prepared according to one of four protocols and the mass determined after drying overnight on waxed paper. In group 1, a 0.1-ml aliquot of TA was dispensed with a 30-gauge needle after shaking the vial 10 or 30 times. Group 2 used a 27-gauge needle. In group 3, the supernatant was removed from the crystals. Group 4 passed the suspension through a 0.2-microm micropore filter and rinsed the crystals with saline. RESULTS: There was no statistically significant difference between 30- or 27-gauge needles (P = 0.83, t test) or between shaking the vial 10 or 30 times before withdrawing the drug (P = 0.99). A statistically significant difference (t test, P = 0.001) was found between TA delivered from the initial 60% of each syringe (mean +/- SD, 2.7 +/- 1.0 mg) to that drawn from the last 40% of each syringe (7.8 +/- 3.6 mg). Group 3 had a mean weight of 32.1 +/- 7.0 mg and group 4, 10.6 +/- 2.1 mg. CONCLUSIONS: Efforts to achieve a 4.0-mg dose of TA, regardless of method used, are variable and inconsistent. Injecting through a small-gauge needle appears to concentrate the remaining suspension. Techniques to concentrate TA or remove aqueous preservatives by filtering effectively increase the concentration, but these results are variable.

Upregulation of RAGE and its ligands in proliferative retinal disease.

We sought to study the presence of the receptor for advanced glycation endproducts (RAGE) and its ligands, advanced glycation endproducts (AGEs), S100/calgranulins and amphoterin (high mobility group box 1 protein; HMGB1), in the vitreous cavity and epiretinal membranes (ERMs) of eyes of patients with proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). Undiluted vitreous specimens were collected from 30 eyes of 30 patients undergoing pars plana vitrectomy for repair of retinal detachment (RD) secondary to PDR (n = 15) or PVR (n = 15). The vitreous samples obtained from 10 eyes undergoing macular hole repair were used as controls. Epiretinal membranes were obtained from eight eyes with PDR and from 10 eyes with PVR. The levels of AGEs in the vitreous were measured using ELISA. The vitreous levels of soluble RAGE (sRAGE), S100/calgranulins and amphoterin were measured using Western blot analyses. The localization of RAGE and its ligands in ERMs was determined with immunohistochemistry. The vitreous levels of sRAGE were significantly increased in both PDR and PVR (p < or = 0.05) compared to control vitreous. In both PDR and PVR, the vitreous levels of AGEs (p < or = 0.01), S100/calgranulins (p < or = 0.05), and amphoterin (p < or = 0.01) were also elevated compared to control eyes. Expression of RAGE was detected in six of eight ERMs from eyes with PDR and eight of 10 ERMs from eyes with PVR. Many cells expressing RAGE also expressed vimentin, suggesting a glial cell origin. Ligands for RAGE were also detected in ERMs, with AGEs detected in five eyes with PDR and eight eyes with PVR. Similarly, S100 and amphoterin ERM expression was observed in six eyes with PDR; these ligands were also expressed in ERMs from eyes with PVR (8 and 7 cases, respectively). We conclude that RAGE and its ligands are increased in the vitreous cavity of eyes with PDR and PVR and are present in ERMs of eyes with these proliferative retinal disorders. These findings suggest a role for the proinflammatory RAGE axis in the pathogenesis of proliferative retinal diseases.

The RAGE axis in early diabetic retinopathy.

PURPOSE: The receptor for advanced glycation end products (AGEs) has been implicated in the pathogenesis of diabetic complications. This study was conducted to characterize the role of the RAGE axis in a murine model of nonproliferative diabetic retinopathy (NPDR). METHODS: The retinas of hyperglycemic, hyperlipidemic (HGHL, apolipoprotein E(-/-) db/db) mice were examined for the development of early retinal vascular lesions of NPDR and compared to littermates at 6 months of age. Neural function was assessed with electroretinography. Immunohistochemistry, real-time RT-PCR, autofluorescence, and ELISA studies were used to localize and quantify the AGE/RAGE axis. Soluble RAGE, a competitor of cellular RAGE for its ligands, was administered to assess the impact of RAGE blockade. RESULTS: Early inner retinal neuronal dysfunction, manifested by prolonged latencies of the oscillatory potentials and b-wave, was detected in hyperglycemic mice. HGHL mice exhibited accelerated development of acellular capillaries and pericyte ghosts compared with littermate control animals. AGEs were localized primarily to the vitreous cavity and internal limiting membrane (ILM) of the retina, where they were intimately associated with the footplates of RAGE-expressing Müller cells. AGE accumulation measured by ELISA was increased within the retinal extracellular matrix of hyperglycemic mice. AGE fluorescence and upregulation of RAGE transcripts was highest in the retinas of HGHL mice, and attenuation of the RAGE axis with soluble RAGE ameliorated neuronal dysfunction and reduced the development of capillary lesions in these mice. CONCLUSIONS: In early diabetic retinopathy, the RAGE axis, comprising the cellular receptor and its AGE ligands, is amplified within the retina and is accentuated along the vitreoretinal interface. Antagonism of the RAGE axis in NPDR reduces neurovascular perturbations, providing an important therapeutic target for intervention.