Tomonari Ojima

Measurement of Retinal Nerve Fiber Layer Thickness and Macular Volume for Glaucoma Detection Using Optical Coherence Tomography

PurposeTo evaluate retinal nerve fiber layer (RNFL) thickness and macular volume in normal eyes and in the eyes of patients with glaucoma, and to compare the usefulness of these measurements in diagnosing glaucomatous eyes.MethodsEighty-one eyes were divided into three groups: normal control (n = 31), early glaucoma [n = 31, mean deviation (MD) ≥ −6 dB], and advanced glaucoma (n = 19, MD < −6 dB). The RNFL thickness and macular volume were measured using Stratus OCT (optical coherence tomography). Then, the diagnostic power of these parameters was evaluated.ResultsIn eyes with early glaucoma, RNFL thickness was decreased significantly in eight of the 12 peripapillary sectors, and macular volume was decreased significantly in six of the nine macular sectors, compared with normal eyes. In the advanced glaucoma eyes, RNFL and macular volume were decreased throughout, except in RNFL thickness in the papillomacular region, and in retinal thickness in the foveal region. The area under the receiver-operating characteristic curve (AUROC) of the average RNFL (0.963) was larger than the macular volume (0.919).ConclusionsBoth peripapillary RNFL thickness and macular volume were decreased even in the early stage of glaucoma. Average RNFL thickness had greater diagnostic power than macular volume. Jpn J Ophthalmol 2007;51:197–203

Transcription Factor Ets-1 Mediates Ischemia- and Vascular Endothelial Growth Factor-Dependent Retinal Neovascularization

Transcription factor Ets-1 has been reported to regulate angiogenesis in vascular endothelial cells. Here, we investigated a mechanism that may regulate the expression of Ets-1 in vascular endothelial growth factor (VEGF)- and hypoxia-induced retinal neovascularization and that may have potential to inhibit ocular neovascular diseases. VEGF and hypoxia increased Ets-1 expression in cultured bovine retinal endothelial cells. The VEGF-induced mRNA increase of Ets-1 was suppressed by a tyrosine kinase inhibitor (genistein), by inhibitors of MEK (mitogen-activated protein and extracellular signal-regulated kinase kinase) (PD98059 and UO126), and by inhibitors of protein kinase C (GF109203X, staurosporine, and Gö6976). Dominant-negative Ets-1 inhibited VEGF-induced cell proliferation, tube formation, and the expression of neuropilin-1 and angiopoietin-2. In a mouse model of proliferative retinopathy, Ets-1 mRNA was up-regulated. Intravitreal injection of dominant-negative Ets-1 suppressed retinal angiogenesis in a mouse model of proliferative retinopathy. In conclusion, VEGF induces Ets-1 expression in bovine retinal endothelial cells and its expression is protein kinase C/ERK pathway-dependent. Ets-1 up-regulation is involved in the development of retinal neovascularization, and inhibition of Ets-1 may be beneficial in the treatment of ischemic ocular diseases.

Cyclic Stretch–Induced Reactive Oxygen Species Generation Enhances Apoptosis in Retinal Pericytes Through c-Jun NH2-Terminal Kinase Activation

Hypertension is known to exacerbate diabetic complications, such as retinopathy and nephropathy. Apoptosis of retinal vascular pericytes has been well established as the earliest conceivable change in diabetic retinopathy. In this study, we investigated the contribution of cyclic stretch, which mimics a hypertensive state to pericyte apoptosis. A 48-hour cyclic stretch induced DNA fragmentation in porcine retinal pericytes and increased the number of TUNEL+ cells at a pathophysiologically relevant extension level (10%/60 cycles per minute). Stretch also increased intracellular reactive oxygen species generation and increased c-Jun NH2-terminal kinase phosphorylation in a time- and magnitude-dependent manner, which were reduced by the nicotinamide-adenine dinucleotide phosphate oxidase inhibitor diphenylene iodonium or dominant-negative protein kinase C-&dgr;. Stretch activated protein kinase C-&dgr; and increased its association with p47phox. Stretch induced cleavage of caspase-9 and -3 and increased caspase-3 activity. Protein kinase C-&dgr; or c-Jun NH2-terminal kinase inhibition normalized stretch-induced caspase-3 activity and prevented stretch-induced apoptosis. These data indicate that cyclic stretch induces apoptosis in porcine retinal pericytes by activation of the reactive oxygen species–c-Jun NH2-terminal kinase–caspase cascades, suggesting a novel molecular mechanism to explain the exacerbation of early diabetic retinopathy by concomitant hypertension.

Role of vitronectin receptor-type integrins and osteopontin in ischemia-induced retinal neovascularization.

PURPOSE It has been reported that vitronectin receptor-type integrins mediate vascular cell proliferation and migration. In this study, we investigated the expression of vitronectin receptor-type integrins and osteopontin in ischemia-induced retinal neovascularization, and examined the role of osteopontin in angiogenesis as a ligand of vitronectin receptor-type integrins. METHODS Retinal neovascularization was produced by exposing C57BL/6J mice to 75% oxygen from postnatal day (P) 7 to P12. Expression of vitronectin receptor-type integrins and osteopontin was assessed by Northern blot analysis, in situ hybridization, and immunofluorescence. The role of osteopontin in retinal angiogenesis was evaluated by tube formation assay using cultured bovine retinal microcapillary endothelial cells. RESULTS In the murine model, integrin alpha(v) mRNA was increased from P14 with a 2.6-fold peak response observed on P19, when retinal neovascularization was remarkable. Indirect immunofluorescence for vitronectin receptor-type integrins revealed prominent expression of integrin alpha(v)beta3/beta5 in the neovascular endothelial cells. Osteopontin mRNA was increased from P14, with a 2.0-fold peak response observed on P19. In situ hybridization demonstrated localization of osteopontin mRNA in neovascular tufts. Vascular endothelial growth factor-induced tube formation (8.3 +/- 0.6 mm/field) was inhibited significantly by treatment with anti-osteopontin antibody (4.8 +/- 0.7 mm/field, P <.001). CONCLUSIONS These data suggest that increased expression of both vitronectin receptor-type integrins and osteopontin in ischemic retina contribute to vascular endothelial cell proliferation and to retinal vascular formation by promoting interaction between endothelial cells and extracellular matrix, which leads to retinal neovascularization.

Fixation behavior in advanced stage glaucoma assessed by the MicroPerimeter MP-1.

PurposeTo investigate fixation behavior in eyes with advanced glaucoma using the MicroPerimeter MP-1.MethodsWe retrospectively reviewed 39 glaucoma patients who had scotomas adjacent to fixation points. Using the MP-1, we examined the stability and location of fixation with the fixation test and the microperimetry test. We examined retinal sensitivity using the central 10–2 SITA standard programs of a Humphrey Field Analyzer and the macula 10° program of the MP-1 and analyzed the correlation between fixation behavior and retinal sensitivity.ResultsOf the 39 eyes, 37 showed “stable” fixation in the fixation test, while 30 eyes showed stable fixation in the microperimetry test. In the fixation test, 32 of 39 eyes demonstrated “predominantly central” fixation, whereas in the microperimetry test only 26 eyes exhibited the same fixation. Fixation stability correlated positively with sensitivity in the central 10° diameter area (r = 0.414, P = 0.009). Among the six eyes showing “predominantly eccentric” fixation, the preferred retinal locus of five was in the superior or superotemporal direction from the fovea.ConclusionsThe MP-1 illustrated the fixation patterns in glaucomatous eyes and the fixation patterns correlated well with retinal sensitivity.

Retinal nerve fibre layer assessment in myopic glaucomatous eyes : comparison of GDx variable corneal compensation with GDx enhanced corneal compensation

Aim: To compare the results of scanning laser polarimetry (GDx) with variable corneal compensation (VCC) and enhanced corneal compensation (ECC) when applied to myopic glaucomatous eyes. Methods: Forty glaucoma eyes with moderate myopia (between −3 and −6 D) and 35 glaucoma eyes with high myopia (−8 D or greater) were enrolled in this study. GDx VCC, GDx ECC and standard automated perimetry (SAP) were performed. The prevalence of an atypical retardation pattern (ARP), the typical scan score (TSS) and retinal nerve fibre layer (RNFL) thickness were compared between VCC and ECC in both groups of myopic subjects. A correlation analysis between RNFL thickness and visual sensitivity was also conducted. Results: In both myopic groups, the mean TSS is significantly lower (p<0.0001), and the prevalence of ARP was significantly higher (p<0.0001) by VCC scans than by ECC scans. Temporal, superior, nasal, inferior, temporal (TSNIT) average and temporal average thickness showed significantly higher values (p<0.001) by VCC than by ECC. A statistically significant association was observed between TSNIT average and mean deviation of SAP by ECC scan. Conclusions: ECC scans showed a better retardation pattern and structure–function relationship than did VCC, and ECC appeared to be more suitable for RNFL assessment in glaucomatous eyes that are moderately to highly myopic.