Yasutomo Tsukahara

Visual Function Following Congenital Cataract Surgery

To evaluate the results of congenital cataract extraction and postoperative visual function, we retrospectively reviewed the records of 95 patients who underwent pars plana (plicata) lensectomy or aspiration surgery. Forty-nine percent of the patients with bilateral aphakia and 25% with bilateral pseudophakia had a Landolt visual acuity of 0.5 or above at the final visit. The figures were 31% and 66% for patients with unilateral aphakia and pseudophakia, respectively. Eight patients (16.3%) with bilateral and 2 patients (5.8%) with unilateral cataract for whom contact lenses were prescribed after surgery attained fine stereopsis. Five of 8 patients (62.5%) with unilateral cataract who had intraocular lens implantation ended up with gross or fine stereopsis. We stress that very early surgery and optical correction in the sensitive period of binocular visual development should be instituted, especially in the presence of dense opacities. A good postoperative visual outcome can be achieved in patients undergoing late surgery if the opacities are light or partial in nature. We also reemphasize the importance of aggressive and diligent visual rehabilitation and occlusion therapy against amblyopia.

Expression of ATP-binding cassette transporters at the inner blood-retinal barrier in a neonatal mouse model of oxygen-induced retinopathy.

ATP-binding cassette (ABC) transporters at the blood-brain barrier (BBB) are responsible for the majority of the transcellular movement of various substrates, including various drugs, and contribute to the maintenance of brain homeostasis. Clinically, the abnormal expression of efflux transporters at the BBB is known to be associated with brain diseases such as epilepsy. In the retina, vascular endothelial cells outline the inner blood-retinal barrier (BRB) like the BBB, and some ABC efflux transporters are expressed in the adult retina. However, little is known about ABC transporter expression during retinal development or under pathological conditions. Here, we examined ABC transporter expression in the mouse retina, and demonstrated that P-glycoprotein (P-gp)/ABCB1, Mrp4/ABCC4, and Bcrp/ABCG2 were almost uniformly expressed in these blood vessels, including the capillaries and large vessels. This expression persisted throughout the developmental period, and the hyaloid vessels that normally feed the developing eye were immunoreactive for P-gp and Mrp4. Furthermore, we investigated ABC transporter expression in pathological angiogenesis using an oxygen-induced retinopathy model where hypoxia-induced preretinal neovascularization occurred around the central avascular retina. P-gp was prominently immunoexpressed but Mrp4 and Bcrp were weakly immunoexpressed, in the preretinal neovascular tufts. These findings will be helpful for understanding the roles of ABC transporters during both physiological and pathological retinal angiogenesis, and might provide new insights for safe and effective drug administration to infants or patients with angiogenic ocular disease.

Laser flare intensity in diabetics: correlation with retinopathy and aqueous protein concentration.

The laser flare intensity in diabetics, measured with the scattering of a light beam, was evaluated and compared with actual aqueous protein concentration obtained during surgery. Measurement of the laser flare intensity in 120 diabetics and 108 normal subjects was performed with the laser flare cell meter (FC1000 Kowa, Tokyo). Aqueous protein concentration in 26 diabetics and six controls who underwent intraocular surgery was measured by the method of Bradford. No significant difference in the laser flare intensity was found between normal subjects and diabetics without retinopathy. A significant increase in the laser flare intensity was observed after six decades in diabetics with background retinopathy and all with proliferative retinopathy. The laser flare intensity correlated with the duration of diabetes mellitus. There was a significant linear relation between the laser flare intensity and actual aqueous protein concentration. The linear regression formula was X = Y1.39 x 1.02 (X = protein concentration, mg/dl; Y = flare intensity, photon counts/ms). The precise value of the laser flare intensity provides a new indicator to evaluate the diabetic change in the function of the ocular barrier.

Early Responses to Intravitreal Ranibizumab in Typical Neovascular Age-Related Macular Degeneration and Polypoidal Choroidal Vasculopathy

Purpose. To evaluate the early response to intravitreal ranibizumab (IVR) in two different phenotypes of age-related macular degenerations (AMD): typical neovascular AMD (tAMD) and polypoidal choroidal vasculopathy (PCV). Methods. Sixty eyes from 60 patients (tAMD 28, PCV 32 eyes) were recruited. Three consecutive IVR treatments (0.5 mg) were performed every month. Change in the best-corrected visual acuity (BCVA) and central retinal thickness (CRT) was then compared between the tAMD and PCV groups. Results. The mean BCVA logMAR was significantly improved at month 1 and month 3 after the initial IVR in the tAMD group, but there was no change in the PCV group. Both phenotypes showed significant improvements in the CRT during the 3 months after the initial IVR. There were no significant differences in the improvements of the CRT in the tAMD versus the PCV group. In the stepwise analysis, a worse pretreatment BCVA and tAMD lesions were significantly beneficial for a greater improvement of BCVA at 3 months after the initial IVR. Conclusions. The phenotype of tAMD showed a significantly better early response to IVR than PCV in terms of BCVA improvement.

A Common Complement C3 Variant Is Associated with Protection against Wet Age-Related Macular Degeneration in a Japanese Population

Background Genetic variants in the complement component 3 gene (C3) have been shown to be associated with age-related macular degeneration (AMD) in Caucasian populations of European descent. In particular, a nonsynonymous coding variant, rs2230199 (R102G), is presumed to be the most likely causal variant in the C3 locus based on strong statistical evidence for disease association and mechanistic functional evidence. However, the risk allele is absent or rare (<1%) in Japanese and Chinese populations, and the association of R102G with AMD has not been reported in Asian populations. Genetic heterogeneity of disease-associated variants among different ethnicities is common in complex diseases. Here, we sought to examine whether other common variants in C3 are associated with wet AMD, a common advanced-stage manifestation of AMD, in a Japanese population. Methodology/Principal Findings We genotyped 13 tag single nucleotide polymorphisms (SNPs) that capture the majority of common variations in the C3 locus and tested for associations between these SNPs and wet AMD in a Japanese population comprising 420 case subjects and 197 controls. A noncoding variant in C3 (rs2241394) exhibited statistically significant evidence of association (allelic P = 8.32×10−4; odds ratio = 0.48 [95% CI = 0.31–0.74] for the rs2241394 C allele). Multilocus logistic regression analysis confirmed that the effect of rs2241394 was independent of the previously described loci at ARMS2 and CFH, and that the model including variants in ARMS2 and CFH plus C3 rs2241394 provided a better fit than the model without rs2241394. We found no evidence of epistasis between variants in C3 and CFH, despite the fact that they are involved in the same biological pathway. Conclusions Our study provides evidence that C3 is a common AMD-associated locus that transcends racial boundaries and provides an impetus for more detailed genetic characterization of the C3 locus in Asian populations.

Evaluation of clinical and genetic indicators for the early response to intravitreal ranibizumab in exudative age-related macular degeneration

AIM This study was conducted to evaluate the possible clinical and genetic indicators for an early response to intravitreal ranibizumab (IVR) in exudative age-related macular degeneration (AMD). PATIENTS & METHODS The records of 120 eyes from 120 Japanese patients with treatment-naive exudative AMD were retrospectively reviewed. Three consecutive IVR treatments were performed every month. Achievement of anatomical resolution was evaluated by ophthalmoscopy and optical coherence tomography. Multivariable logistic regression analysis was conducted by analyzing SNPs in the ARMS2 locus (A69S) and in the CFH gene (I62V and Y402H), in addition to clinical factors. RESULTS The mean central retinal thickness of overall patients was significantly decreased (-120.1 ± 122.8 µm, p = 2.7 × 10(-19)) at 3 months after the initial treatment. In the logistic regression analysis, the poor anatomical resolution of the lesion at 3 months was associated with the combination of CFH I62V + CFH Y402H variants (p = 0.0021), and the polypoidal choroidal vasculopathy lesions (p = 0.044). CONCLUSION The CFH variants and the polypoidal choroidal vasculopathy lesion may influence the early anatomical resolution with IVR in exudative AMD.

MRP4 knockdown enhances migration, suppresses apoptosis, and produces aggregated morphology in human retinal vascular endothelial cells

The multidrug resistance protein (MRP) MRP4/ABCC4 is an ATP-binding cassette transporter that actively effluxes endogenous and xenobiotic substrates out of cells. In the rodent retina, Mrp4 mRNA and protein are exclusively expressed in vascular endothelial cells, but the angiogenic properties of Mrp4 are poorly understood so far. This study aims to explore the angiogenic properties of MRP4 in human retinal microvascular endothelial cells (HRECs) utilizing the RNA interference (RNAi) technique. MRP4 expression was decreased at the mRNA and protein levels after stimulation with exogenous vascular endothelial growth factor in a dose-dependent manner. RNAi-mediated MRP4 knockdown in HRECs do not affect cell proliferation but enhances cell migration. Moreover, cell apoptosis induced by serum starvation was less prominent in MRP4 siRNA-treated HRECs as compared to control siRNA-treated HRECs. In a Matrigel-based tube-formation assay, although MRP4 knockdown did not lead to a significant change in the total tube length, MRP4 siRNA-treated HRECs assembled and aggregated into a massive tube-like structure, which was not observed in control siRNA-treated HRECs. These results suggest that MRP4 is uniquely involved in retinal angiogenesis.

The upregulation of angiogenic gene expression in cultured retinal pigment epithelial cells grown on type I collagen.

Purpose: Increases in matrix proteins, such as type I collagen and fibronectin, are observed with aging in the retinal pigment epithelium (RPE) basement membrane. However, little is known about altered gene expression profiles of RPE associated with increases in matrix proteins. We investigated changes in gene expression profiles of a human RPE cell line (ARPE-19) cultured on type I collagen. Methods: Visually confluent ARPE-19 cells were grown on either Matrigel (M group) or type I collagen (C group) without serum over 3 days. Total RNA was extracted and reverse transcribed. Gene expression profiles in both groups were compared using microarray analyses. Several angiogenic genes including integrin alpha V, integrin alpha 2, integrin beta 1, integrin beta 3, VEGF-A, VEGF-B, and VEGF-C were subjected to quantitative analyses using real-time PCR. Results: Out of 192 genes examined, angiogenesis-related genes (17.7%) and extracellular matrix–related genes (30.2%) were expressed highly (with more than 1.5-fold difference) in the C group when compared with the M group. In real-time PCR analyses, all VEGF and integrin family genes examined were expressed more in the C group than in the M group. Conclusions: Type I collagen likely causes an upregulation in a number of angiogenic gene expression patterns as seen in RPE in vitro experiments.

Different transitions of multifocal electroretinogram recordings between patients with age-related macular degeneration and polypoidal choroidal vasculopathy after photodynamic therapy.

Aim: To compare and evaluate the transitions in retinal function after photodynamic therapy (PDT) between age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) using multifocal electroretinograms (mfERGs). Methods: 10 eyes with choroidal neovascularisation (CNV) secondary to AMD and 11 eyes with CNV secondary to PCV were included in the study. mfERGs were recorded before PDT, and 1 week and 3 months after PDT. mfERG recordings were acquired by a Veris system (V.3.1.3) using a 103 hexagon stimulus. The first-order kernel was used to calculate amplitudes and latencies. Mean amplitudes and latencies from two central rings rated 0–4° of visual angle were analysed and compared with each disease. Results: In AMD, the mean first negative peak (N1) amplitudes tended to decrease, and the mean first positive peak (N1P1) amplitudes reduced to significant levels (p = 0.047) 1 week after PDT. 3 months after PDT, there were no significant differences in the mean N1 and N1P1 amplitudes compared with pre-PDT values. In PCV, there were no significant changes in the mean N1 and N1P1 amplitudes 1 week after treatment. However, 3 months after PDT, mean amplitudes showed significant increases in N1 (p = 0.008) and N1P1 (p = 0.006) amplitudes compared with pre-PDT values. Conclusions: mfERG recording transitions are different between patients with AMD and those with PCV. In patients with AMD, these results may show transient impairments in retinal function 1 week after PDT, but in those with PCV, the efficacy of PDT is superior to the impairment after PDT.

Disruption of the Blood-Aqueous Barrier following Retinal Laser Photocoagulation and Cryopexy in Pigmented Rabbits

Disruption of the blood-aqueous barrier (BAB) induced by retinal photocoagulation and cryopexy in pigmented rabbits was evaluated by laser flare photometry. A significant increase in flare values after retinal photocoagulation was measured from the 1st postoperative day, with values returning to baseline levels by day 7. Cryopexy induced consistently high flare values for 14 days. Intravitreal injection of interleukin (IL) 1, IL-6 and prostaglandin (PG) E2 induced a significant increase in flare values. Following these treatments, introduction of a PG synthetase inhibitor can partially ameliorate BAB disruption. IL-1, IL-6 and PGE2 may be involved in BAB disruption following retinal photocoagulation and cryopexy.