Hidetaka Matsumoto

Tomographic features of branching vascular networks in polypoidal choroidal vasculopathy.

Purpose: To identify the tomographic features of the branching vascular networks in patients with polypoidal choroidal vasculopathy (PCV). Methods: We prospectively performed third-generation optical coherence tomography (OCT) and fluorescein angiography for 44 eyes of 42 patients (mean age ± SD, 67.1 ± 9.1 years) with PCV. All eyes had branching vascular networks and polypoidal lesions that were confirmed by indocyanine green angiography. Results: OCT showed double reflective layers that consisted of retinal pigment epithelium (RPE) and another highly reflective layer beneath the RPE (“double-layer sign”) in the area of the branching network vessels in 26 (59%) of 44 eyes. The remaining 18 eyes had no double-layer sign, but 17 (94%) of 18 eyes had a slightly elevated RPE. A serous retinal detachment was present in 23 (88%) of 26 eyes with a double-layer sign, while only 1 (6%) of 18 eyes without the sign had a serous retinal detachment. Conclusions: In PCV, the double-layer sign is seen frequently in the area of the network vessels, particularly in eyes with a serous retinal detachment. The sign may reflect fluid accumulation between RPE and Bruch membrane resulting from leakage from the network of abnormal vessels.

Outer Nuclear Layer Thickness at the Fovea Determines Visual Outcomes in Resolved Central Serous Chorioretinopathy

PURPOSE To determine a correlation between foveal morphologic changes and visual outcomes in patients with resolved central serous chorioretinopathy (CSC). DESIGN Observational case series. METHODS We measured the outer nuclear layer (ONL) thickness at the central fovea and evaluated the integrity of the photoreceptor inner and outer segment junction (IS/OS) using spectral-domain optical coherence tomography in 67 eyes (65 patients) with resolved CSC. The patients were divided into 2 groups: group A included 24 eyes (23 patients) with best-corrected visual acuity (BCVA) of less than 1.0, and group B included 43 eyes (42 patients) with BCVA of 1.0 or better. Group C was comprised of normal control eyes (10 volunteers). We also determined a correlation between the ONL thickness and BCVA. RESULTS The average ONL thicknesses at the central fovea in groups A, B, and C were 74.6 microm, 103.2 microm, and 124.9 microm, respectively. The average ONL thickness at the central fovea in group A was significantly (P < .001) thinner than that in group B, and that in group B was significantly (P = .0014) thinner than that in group C. The ONL thickness was correlated with the BCVA (r(s) = 0.59; P < .001). Discontinuity of the IS/OS line was observed in 22 eyes (91.7%) in group A, in 9 eyes (20.9%) in group B, and in no eyes in group C, with the difference between groups A and B reaching significance (P < .001). CONCLUSIONS The ONL thickness is positively correlated with the BCVA in resolved CSC. Discontinuity of the IS/OS line was prevalent in eyes with thinner ONL and lower BCVA.

Receptor interacting protein kinase mediates necrotic cone but not rod cell death in a mouse model of inherited degeneration

Retinitis pigmentosa comprises a group of inherited retinal photoreceptor degenerations that lead to progressive loss of vision. Although in most cases rods, but not cones, harbor the deleterious gene mutations, cones do die in this disease, usually after the main phase of rod cell loss. Rod photoreceptor death is characterized by apoptotic features. In contrast, the mechanisms and features of subsequent nonautonomous cone cell death remain largely unknown. In this study, we show that receptor-interacting protein (RIP) kinase mediates necrotic cone cell death in rd10 mice, a mouse model of retinitis pigmentosa caused by a mutation in a rod-specific gene. The expression of RIP3, a key regulator of programmed necrosis, was elevated in rd10 mouse retinas in the phase of cone but not rod degeneration. Although rd10 mice lacking Rip3 developed comparable rod degeneration to control rd10 mice, they displayed a significant preservation of cone cells. Ultrastructural analysis of rd10 mouse retinas revealed that a substantial fraction of dying cones exhibited necrotic morphology, which was rescued by Rip3 deficiency. Additionally, pharmacologic treatment with a RIP kinase inhibitor attenuated histological and functional deficits of cones in rd10 mice. Thus, necrotic mechanisms involving RIP kinase are crucial in cone cell death in inherited retinal degeneration, suggesting the RIP kinase pathway as a potential target to protect cone-mediated central and peripheral vision loss in patients with retinitis pigementosa.

Programmed necrosis, not apoptosis, is a key mediator of cell loss and DAMP-mediated inflammation in dsRNA-induced retinal degeneration

There is no known treatment for the dry form of an age-related macular degeneration (AMD). Cell death and inflammation are important biological processes thought to have central role in AMD. Here we show that receptor-interacting protein (RIP) kinase mediates necrosis and enhances inflammation in a mouse model of retinal degeneration induced by dsRNA, a component of drusen in AMD. In contrast to photoreceptor-induced apoptosis, subretinal injection of the dsRNA analog poly(I : C) caused necrosis of the retinal pigment epithelium (RPE), as well as macrophage infiltration into the outer retinas. In Rip3−/− mice, both necrosis and inflammation were prevented, providing substantial protection against poly(I : C)-induced retinal degeneration. Moreover, after poly(I : C) injection, Rip3−/− mice displayed decreased levels of pro-inflammatory cytokines (such as TNF-α and IL-6) in the retina, and attenuated intravitreal release of high-mobility group box-1 (HMGB1), a major damage-associated molecular pattern (DAMP). In vitro, poly(I : C)-induced necrosis were inhibited in Rip3-deficient RPE cells, which in turn suppressed HMGB1 release and dampened TNF-α and IL-6 induction evoked by necrotic supernatants. On the other hand, Rip3 deficiency did not modulate directly TNF-α and IL-6 production after poly(I : C) stimulation in RPE cells or macrophages. Therefore, programmed necrosis is crucial in dsRNA-induced retinal degeneration and may promote inflammation by regulating the release of intracellular DAMPs, suggesting novel therapeutic targets for diseases such as AMD.

Combined photodynamic therapy with verteporfin and intravitreal bevacizumab for polypoidal choroidal vasculopathy.

PURPOSE To evaluate the efficacy of photodynamic therapy with verteporfin with intravitreal bevacizumab for polypoidal choroidal vasculopathy. DESIGN Retrospective case study. METHODS This study included 29 treatment-naïve patients with polypoidal choroidal vasculopathy followed up for 12 months after the first combined therapy. Patients received 1.25 mg intravitreal bevacizumab 1 week before photodynamic therapy with verteporfin. The main outcomes measures were visual acuity and the number of required retreatments. RESULTS The mean best-corrected visual acuity (BCVA) level was 0.25 at baseline and 0.31, 0.39, 0.44, 0.44, and 0.45 at 1, 3, 6, 9, and 12 months after treatment, respectively. A significant (P< .01) improvement in the mean BCVA was observed at 3, 6, 9, and 12 months after combined therapy. At 12 months, the mean improvement in BCVA from baseline was 2.69 lines; the BCVA improved in 15 eyes (51.7%) by 3 lines or more, was stable in 13 eyes (44.8%), and decreased in 1 eye (3%) because of a massive subretinal hemorrhage 7 months after the first treatment. Eighteen eyes (62%) required 1 combined treatment during follow-up. Polypoidal lesions recurred in 6 eyes (21%). An abnormal branching vascular network persisted in all eyes. The mean number of treatments with combined therapy averaged 1.59. No complications, including endophthalmitis, uveitis, or ocular hypertension, developed. CONCLUSIONS Combined treatment consisting of photodynamic therapy with verteporfin and intravitreal bevacizumab for polypoidal choroidal vasculopathy seemed to be effective for improving visual acuity and reducing retreatment rates and complications. Further study is needed to determine the long-term clinical results.

Fundus Autofluorescence of Elongated Photoreceptor Outer Segments in Central Serous Chorioretinopathy

PURPOSE To determine the origin of fundus autofluorescence (AF) patterns in central serous chorioretinopathy (CSC). DESIGN Retrospective, observational case series. METHODS We retrospectively studied 30 consecutive eyes of 30 patients with primary CSC using AF and spectral-domain optical coherence tomography (SD-OCT). We measured the AF using the Heidelberg Retina Angiograph with a 488-nm excitation light and a 500-nm cutoff barrier filter and compared the AF patterns with ophthalmoscopy and SD-OCT. RESULTS We observed a patchy increased AF in the macular area in 22 eyes (73%), in which the length of the photoreceptor outer segment at the central fovea tended to be longer than the other eyes (P=.06). The punctate increased AF corresponded to the ophthalmoscopic precipitates in 17 eyes with precipitates. AF significantly (P=.017) decreased in eyes with a prominent serous retinal detachment (SRD). Eight eyes (27%) had increased AF in the inferior SRD. CONCLUSIONS The patchy increased AF appears to originate from elongated photoreceptor outer segments in the detached retina. The autofluorescent fluorophores from the photoreceptor outer segments may be concentrated in precipitates or have settled into the inferior SRD.

Strain Difference in Photoreceptor Cell Death After Retinal Detachment in Mice

PURPOSE To evaluate the potential for mouse genetic background to effect photoreceptor cell death in response to experimental retinal detachment (RD). METHODS Retinal detachment was induced in three inbred mouse strains (C57BL/6, BALB/c, and B6129SF2) by subretinal injection of sodium hyaluronate. A time course of photoreceptor cell death was assessed by TUNEL assay. Total photoreceptor cell death was analyzed through comparing the outer nuclear layer (ONL)/inner nuclear layer (INL) ratio 7 days post RD. Western blot analysis or quantitative real-time PCR (qPCR) were performed to assess cell death signaling, expression of endogenous neurotrophin, and levels of apoptosis inhibitors 24 hours after RD. Inflammatory cytokine secretion and inflammatory cell infiltration were quantified by ELISA and immunostaining, respectively. RESULTS The peak of photoreceptor cell death after RD was at 24 hours in all strains. Photoreceptor cell death as well as monocyte chemoattractant protein 1 and interleukin 6 secretion at 24 hours after RD was the highest in BALB/c, followed in order of magnitude by C57BL/6 and B6129SF2. Conversely, nerve growth factor expression and ONL/INL ratio were the lowest in BALB/c. Apoptosis signaling was higher in C57BL/6, whereas necroptosis signaling was higher in C57BL/6 and BALB/c. Autophagic signaling was higher in BALB/c. X-linked inhibitor of apoptosis (XIAP) and survivin protein levels were lower in C57BL/6 and BALB/c, respectively. Macrophage/microglia infiltration was higher in C57BL/6 and BALB/c at 24 hours after RD. CONCLUSIONS Photoreceptor cell death after RD was significantly different among the three strains, suggesting the presence of genetic factors that affect photoreceptor cell death after RD.

Tomographic features of intraretinal neovascularization in retinal angiomatous proliferation.

Purpose: The purpose of this study was to define the origin of intraretinal neovascularization in retinal angiomatous proliferation with spectral domain-optical coherence tomography. Methods: We retrospectively studied nine consecutive eyes of seven patients (two eyes of two men, seven eyes of five women) with untreated retinal angiomatous proliferation using fluorescein and indocyanine green angiography and spectral domain-optical coherence tomography. One eye had stage I disease, two eyes had stage II disease with no pigment epithelial detachment, and six eyes had stage II disease with pigment epithelial detachment. We evaluated the location of the intraretinal neovascularization, disruption of the retinal pigment epithelium, retinal edema, and serous retinal detachments. Results: Intraretinal neovascularization appeared as a highly reflective mass from the outer plexiform layer to the deeper layer in seven eyes. The underlying retinal pigment epithelium was disrupted beneath the intraretinal neovascularization in all eyes. All eyes had retinal edema around the intraretinal neovascularization. Serous retinal detachments were seen in only two eyes with stage II disease with pigment epithelial detachment. Intraretinal neovascularization originated outside the foveal avascular zone in all eyes. Conclusion: Intraretinal neovascularization seems to originate from the deep retinal capillaries at the outer plexiform layer and grow toward the retinal pigment epithelium.

Macrophage- and RIP3-dependent inflammasome activation exacerbates retinal detachment-induced photoreceptor cell death

Detachment of photoreceptors from the retinal pigment epithelium is seen in various retinal disorders, resulting in photoreceptor death and subsequent vision loss. Cell death results in the release of endogenous molecules that activate molecular platforms containing caspase-1, termed inflammasomes. Inflammasome activation in retinal diseases has been reported in some cases to be protective and in others to be detrimental, causing neuronal cell death. Moreover, the cellular source of inflammasomes in retinal disorders is not clear. Here, we demonstrate that patients with photoreceptor injury by retinal detachment (RD) have increased levels of cleaved IL-1β, an end product of inflammasome activation. In an animal model of RD, photoreceptor cell death led to activation of endogenous inflammasomes, and this activation was diminished by Rip3 deletion. The major source of Il1b expression was found to be infiltrating macrophages in the subretinal space, rather than dying photoreceptors. Inflammasome inhibition attenuated photoreceptor death after RD. Our data implicate the infiltrating macrophages as a source of damaging inflammasomes after photoreceptor detachment in a RIP3-dependent manner and suggest a novel therapeutic target for treatment of retinal diseases.

Retinal Detachment Model in Rodents by Subretinal Injection of Sodium Hyaluronate

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD).