Shunsuke Yasuda

Significant Correlation between Electroretinogram Parameters and Ocular Vascular Endothelial Growth Factor Concentration in Central Retinal Vein Occlusion Eyes

PURPOSE Central retinal vein occlusion (CRVO) leads to retinal ischemia, which then induces an upregulation of vascular endothelial growth factor (VEGF). The aim of this study was to determine whether a significant correlation exists between the ocular VEGF levels and the amplitudes and implicit times of different components of the electroretinogram (ERG) in eyes with a CRVO. METHODS The medical records of the 20 consecutive patients who had macular edema secondary to CRVO and were examined at the Nagoya University Hospital from November 2008 to February 2010 were reviewed. Because all the patients were scheduled to receive an intravitreal injection of bevacizumab (IVB), it was possible to collect samples of the aqueous humor before the IVB. The correlation between the different components of the ERGs and the VEGF concentration in the aqueous was determined. RESULTS The mean VEGF concentration of the aqueous humor was 416 pg/mL with a range of 100-1260 pg/mL. The b/a ratio of the single flash ERGs (P = 0.049; ρ = -0.45), implicit times of the cone a-wave (P = 0.028; ρ = 0.50), cone b-wave (P = 0.0059; ρ = 0.63), and 30 Hz flicker ERGs (P = 0.0058; ρ = 0.63) were significantly correlated with the VEGF concentration in the aqueous. CONCLUSIONS The significant correlations between the different components of the ERGs and the aqueous VEGF concentration indicate that full-field ERGs can be used to detect the CRVO patients at a high risk of developing neovascularization of the iris.

Rebound of macular edema after intravitreal bevacizumab therapy in eyes with macular edema secondary to branch retinal vein occlusion.

Purpose: To determine the incidence of rebound macular edema after intravitreal bevacizumab in eyes with macular edema secondary to branch retinal vein occlusion and to identify the pretreatment factors that were significantly associated with the rebound. Methods: The changes in the foveal thickness after the intravitreal bevacizumab (1.25 mg/0.05 mL) were studied in 65 eyes of 65 patients with macular edema secondary to branch retinal vein occlusion. A rebound of macular edema was defined as a ≥110% increase in the foveal thickness or a foveal thickness ratio of ≥110% (foveal thickness at the recurrence/foveal thickness at the baseline × 100). Multivariate logistic regression analyses and subgroup analyses were performed to determine which pretreatment factors were associated with the rebound. Results: Seven of 65 eyes (10.8%) showed a rebound (≥110% of baseline thickness). Subgroup analyses showed that a thinner pretreatment fovea and a shorter interval between symptom onset to the initiation of the intravitreal bevacizumab were significantly associated with a rebound of macular edema (P < 0.01). The interval from symptoms onset to the initiation of treatment was <8 weeks in all 7 eyes with a rebound macular edema. Conclusion: These results suggest that a rebound of macular edema in eyes with branch retinal vein occlusion was more likely to occur when the intravitreal bevacizumab therapy is initiated before the macular edema reaches the maximum level. Rebound of macular edema may be effectively avoided by waiting at least 8 weeks after the onset of symptoms to begin the intravitreal bevacizumab.

Focal cone ERGs of rhodopsin Pro347Leu transgenic rabbits.

A rhodopsin P347L transgenic (Tg) rabbit, a model of retinitis pigmentosa, has been generated in our laboratory. The purpose of this study was to determine the properties of focal areas of the retina in this rabbit model during the course of retinal degeneration. To accomplish this, we recorded focal ERGs from wild-type (WT) and Tg rabbits at ages 3, 6, and 12 months. A 15° stimulus spot was used to elicit the focal ERGs from the center of the visual streak and from four surrounding areas. We found that the amplitudes of the focal cone ERG b-waves and oscillatory potentials (OPs) of the Tg rabbits in the five areas decreased progressively with increasing age and became almost non-recordable at 12 months. There were no significant regional differences in the b-waves of Tg rabbits recorded from the 5 areas. The amplitudes of the OPs were better preserved than the b-waves and the OPs/b-wave ratio was higher than that in WT rabbits at every recording area. The summed OPs amplitudes, which most likely originate from the amacrine and/or ganglion cells, recorded from the area superior to the optic disc was significantly larger than that from other areas at 3- and 6-months-old. This indicated that the inner retinal neurons were not altered equally after photoreceptor degeneration in this rabbit model.

Pathologic Changes of Cone Photoreceptors in Eyes With Occult Macular Dystrophy

PURPOSE Occult macular dystrophy (OMD) is an inherited retinal disease characterized by a progressive decrease of vision and appearance of normal fundus. To determine the pathologic features of OMD, we investigated the alternation of the photoreceptors using quantitative image analysis. METHODS We studied 22 eyes of 11 OMD patients. Three of them had a mutation (R45W) in RP1L1. The relative intensities of the ellipsoid zone in the spectral-domain optical coherence tomography (SD-OCT) images and the density of the cone photoreceptors in the adaptive optics (AO) fundus images of the OMD patients were compared to those of normal controls. RESULTS The relative intensities of the ellipsoid zone in the SD-OCT images of patients with OMD were significantly lower (P < 0.001) by an average of 16% compared to that of the normal controls. Normal cone mosaics were not observed in the AO images of the macula in the eyes with OMD. The mean ± SD of cone density of the 9 OMD patients was 1970 ± 884 cells/mm2 at 2°, 1124 ± 483 cells/mm2 at 3°, and 1288 ± 715 cells/mm2 at 4° nasal to the fovea. The cone densities at 2°, 3°, and 4° nasal to the fovea of OMD were significantly lower than those of the normal controls (P < 0.001). CONCLUSIONS A sparse array of cone photoreceptors with significantly reduced density of the macula is one of the morphologic features of OMD.

Restoration of Cone Interdigitation Zone Associated With Improvement of Focal Macular ERG After Fovea-Off Rhegmatogenous Retinal Reattachment

PURPOSE To determine whether a correlation exists between the parameters of the focal macular ERGs (FMERGs) and the microstructural changes of the photoreceptors after successful surgery for fovea-off rhegmatogenous retinal detachment (RRD). METHODS Twenty eyes of 20 patients who had undergone successful surgery to reattach the retina in eyes with fovea-off RRD were studied. Focal macular ERGs and spectral-domain OCT (SD-OCT) were recorded at 1 and 6 months after the surgery. Changes of the components of the FMERGs, as well as changes of the SD-OCT parameters including the length of the external limiting membrane (ELM), ellipsoid zone (EZ), cone interdigitation zone (CIZ), and size of the outer photoreceptor area (between ELM and RPE), were determined. RESULTS During the postoperative period, the mean amplitudes of the a-waves increased by 1.4 times and the b-waves by 1.7 times. Spectral-domain OCT showed that the mean length of the EZ and CIZ and the size of the outer photoreceptor area had increased significantly at 6 months. The degree of the increase in the CIZ and outer photoreceptor area was significantly correlated with the increase in the amplitudes of the b-waves of the FMERGs (r = 0.56, P = 0.042, r = 0.57, P = 0.040, respectively; Spearman rank correlation test). However, the length of the EZ was not significantly correlated with the increase of the b-waves. CONCLUSIONS A restoration of the EZ alone might not be enough to improve the FMERGs, and a restoration of the EZ accompanied by that of the CIZ was essential for the recovery of the FMERGs after fovea-off RRD.

Degeneration of Retinal ON Bipolar Cells Induced by Serum Including Autoantibody against TRPM1 in Mouse Model of Paraneoplastic Retinopathy

The paraneoplastic retinopathies (PRs) are a group of eye diseases characterized by a sudden and progressive dysfunction of the retina caused by an antibody against a protein in a neoplasm. Evidence has been obtained that the transient receptor potential melastatin 1 (TRPM1) protein was one of the antigens for the autoantibody against the ON bipolar cells in PR patients. However, it has not been determined how the autoantibody causes the dysfunction of the ON bipolar cells. We hypothesized that the antibody against TRPM1 in the serum of patients with PR causes a degeneration of retinal ON bipolar cells. To test this hypothesis, we injected the serum from the PR patient, previously shown to contain anti-TRPM1 antibodies by westerblot, intravitreally into mice and examined the effects on the retina. We found that the electroretinograms (ERGs) of the mice were altered acutely after the injection, and the shape of the ERGs resembled that of the patient with PR. Immunohistochemical analysis of the eyes injected with the serum showed immunoreactivity against bipolar cells only in wild-type animals and not in TRPM1 knockout mice,consistent with the serum containing anti-TRPM1 antibodies. Histology also showed that some of the bipolar cells were apoptotic by 5 hours after the injection in wild type mice, but no bipolar cell death was found in TRPM1 knockout mice, . At 3 months, the inner nuclear layer was thinner and the amplitudes of the ERGs were still reduced. These results indicate that the serum of a patient with PR contained an antibody against TRPM1 caused an acute death of retinal ON bipolar cells of mice.

Longitudinal study of visual field changes determined by Humphrey Field Analyzer 10-2 in patients with Retinitis Pigmentosa

The aim of this study is to determine the progress of the visual field defects obtained by the Humphrey Field Analyzer 10-2 program (HFA 10-2) in patients with retinitis pigmentosa (RP). The medical records of 45 eyes of 45 RP patients who had at least 3 visual field tests were reviewed. Linear mixed models were used to follow the changes of the mean deviation and the average sensitivity of 4, 12, and 20 points in three concentric squares, designated as S4, S12, and S20. The median follow-up time was 3.86 years [range: 1.93 to 9.86, IQR (Interquartile range): 3.01 to 4.93]. The median number of the visual field tests was 3 (range: 3 to 15, IQR: 3 to 4). The mean change of the MD was −0.46 dB/year (−5.80%/year). When the patients were grouped by the average initial MD, the less advanced group had slower progressions than the more advanced group in S4, S12, and S20. These results should be useful in understanding the pathological changes of RP in the central visual field.

Changes in Retinal Microcirculation After Intravitreal Ranibizumab Injection in Eyes With Macular Edema Secondary to Branch Retinal Vein Occlusion

Purpose To evaluate the effects of an intravitreal ranibizumab (IVR) injection on the retinal microcirculation of eyes with macular edema secondary to a branch retinal vein occlusion (BRVO). Methods Twenty-six eyes of 26 patients with macular edema due to a BRVO that had received a single IVR injection (0.5 mg/0.05 mL) were studied. The retinal microcirculation was assessed by laser speckle flowgraphy (LSFG) using the mean blur rate (MBR) and relative flow volume (RFV). The size of the retinal arteries and veins surrounding the optic nerve head were measured separately. All of the examinations were made before, and at 1 week, and 1 and 2 months after the IVR. Results The visual acuity improved significantly, and the mean central macular thickness decreased significantly during the follow-up period (both P < 0.001). The mean MBRall and MBRtissue decreased significantly at 1 week and 1 month after the IVR (both P < 0.001). The total RFV of the arteries and veins decreased significantly at 1 week and 1 month after the IVR injection in the occluded and nonoccluded quadrants (all P < 0.001). The width of the arteries and veins in the LSFG images decreased significantly at 1 week and 1 month after the IVR injection (P < 0.001). Conclusions An IVR injection leads to a transient vasoconstriction of the retinal arteries and veins and a reduction of the retinal blood flow and velocity in both the occluded and nonoccluded quadrants. The changes in retinal microcirculation might be related to the improvement of the macular edema and vision.

Increased Ocular Levels of MicroRNA-148a in Cases of Retinal Detachment Promote Epithelial–Mesenchymal Transition

PURPOSE The purpose of this study was to determine microRNA expression in vitreous and subretinal fluid (SRF) samples from patients with retinal detachment (RD). The pathological importance of the identified microRNA transcript levels was analyzed in vitro. METHODS Vitreous fluid was collected from 10 patients with macular hole (MH), vitreomacular traction syndrome (VMTS), or foveoschisis and from 11 patients with RD. Subretinal fluid was collected from 7 patients with RD. Of these, blood serum was collected in 4 patients. MicroRNA microarray profiling was performed to identify microRNA transcripts that were present in vitreous fluid, and more redundantly detected in SRF, of patients with RD, but not detected in control eyes. Western blotting and scratch assays were performed in ARPE-19 cells and primary human RPE cell lines transfected with microRNA to elucidate the effect of identified microRNA transcripts on epithelial-mesenchymal transition (EMT). RESULTS MicroRNA microarray profiling revealed that hsa-miR-148a-3p was the most redundantly detected transcript in SRF and vitreous fluid from patients with RD, but not those with the other diseases. Expression levels of hsa-miR-148a-3p were higher in SRF samples than in blood serum samples in 3 out of 4 patients. Following hsa-miR-148a-3p mimic transfection, ARPE-19 and human RPE cells demonstrated increased expression of α-smooth muscle actin by Western blotting and increased migration ability during scratch assays. CONCLUSIONS The results of the present study indicate that hsa-miR-148a-3p was specifically detected in RD and promotes EMT in RPE.

Significant Correlation between Retinal Venous Tortuosity and Aqueous Vascular Endothelial Growth Factor Concentration in Eyes with Central Retinal Vein Occlusion

Purpose To determine whether the degree of venous tortuosity is significantly correlated with the aqueous vascular endothelial growth factor (VEGF) concentration in eyes with a central retinal vein occlusion (CRVO). Methods We reviewed the medical records of 32 eyes of 32 patients who had macular edema due to a CRVO. All of the patients were examined at the Nagoya University Hospital and were scheduled to receive an intravitreal injection of bevacizumab (IVB) or ranibizumab (IVR) within 12 weeks of the onset of the CRVO to treat the macular edema. Aqueous humor was collected just before the IVB or IVR, and the VEGF concentration was determined by enzyme-linked immunosorbent assay (ELISA). The venous tortuosity index was calculated by dividing the length of the retinal veins by the chord length of the same segment. The correlation between the mean tortuosity index of the inferotemporal and supratemporal branches of the retinal vein and the aqueous VEGF concentration was determined. Results The mean aqueous VEGF concentration was 384 ± 312 pg/ml with a range of 90 to 1077 pg/ml. The degree of venous tortuosity was significantly correlated with the VEGF concentration in the aqueous. (r = 0.49, P = 0.004), with the foveal thickness (r = 0.40, P = 0.02), and with the best-corrected visual acuity (r = 0.38, P = 0.03). Conclusions The significant correlation between the aqueous VEGF concentration and the venous tortuosity indicates that the degree of retinal venous tortuosity can be used to identify eyes that are at a high risk of developing neovascularization.