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PubMedDate not supplied

Correlation between higher blood flow velocity in the central retinal vein than in the central retinal artery and severity of nonproliferative diabetic retinopathy.

PURPOSE: To assess the correlation between a higher blood flow velocity in the central retinal vein (CRV) than in the central retinal artery (CRA) and the severity of nonproliferative diabetic retinopathy (non-PDR). METHODS: We evaluated both eyes of 20 non-PDR patients with higher peak systolic velocity (PSV) in the CRV than in the CRA unilaterally as determined by color Doppler imaging (CDI). The eyes with higher PSV in the CRV were placed in group D2-H, and the fellow eyes were placed in group D2-L. The stage of non-PDR was determined by the guidelines of the Early Treatment Diabetic Retinopathy Study. Normal subjects and non-PDR patients without higher PSV in the CRV were evaluated as CDI controls. RESULTS: Advanced non-PDR (P=0.001) and cystoid macular edema (P=0.02) were statistically more frequent in group D2-H. The velocities in the ophthalmic artery and the short posterior ciliary artery were not statistically different among all groups. The velocities in the CRA were similar in all non-PDR groups and significantly lower than in the normal subjects (P<0.05). The velocities in the CRV were significantly higher only in group D2-H (P<0.001). CONCLUSION: Higher PSV in the CRV than in the CRA was significantly correlated with the severity of non-PDR, especially in the presence of cystoid macular edema.

Aged↗
PubMed1996

Abnormalities of the retinal cone system in retinitis pigmentosa.

Patients with retinitis pigmentosa (RP) show delayed inner retinal responses as measured by the cone ERG response to a 30 Hz stimulus. To determine the extent to which this delay results from abnormalities of cone phototransduction, cone ERGs to single flashes were obtained from 21 patients with RP and a model of cone phototransduction was fitted to the leading edge of the a-waves of these ERGs. Nearly all patients showed an abnormally low sensitivity of cone phototransduction consistent with a reduction in the amplification of transduction. This abnormality can account for part of the delayed 30 Hz response. Analysis of post-receptoral potentials indicated that RP also slows the responses of the inner retina. A combination of these two factors, a sensitivity change at the receptor and a delay in the response of the inner retina, produces the delayed response of the cone flicker ERG in patients with RP.

Adaptation, Ocular↗
PubMed2005

Central retinal vein occlusion with further reduction of retinal blood flow one year after radial optic neurotomy.

PURPOSE: To report a case of central retinal vein occlusion (CRVO) that had vitrectomy with radial optic neurotomy (RON), but the retinal blood flow (RBF) was still reduced 1 year later. DESIGN: Interventional case report. METHODS: An 80-year-old woman had undergone vitrectomy and RON for a CRVO. She had a complete ophthalmic examination, including the RBF analysis using the dye dilution method before and after RON. RESULTS: Seven months after RON, her visual acuity improved from 20/50 to 20/25, and her foveal thickness was decreased from 733 to 213 microm. Indocyanine green angiography demonstrated chorioretinal anastomoses. At 1 year postoperatively, the RBF was reduced from 23.2 to 18 0.1 pixel(2)/s, and the foveal thickness was increased to 767 microm. Her visual acuity decreased to 20/100. The chorioretinal anastomoses were still patent. CONCLUSIONS: These results demonstrate that a further reduction of RBF can occur after RON, and blood flow in the chorioretinal anastomoses may be insufficient to prevent the event.

Aged↗
PubMed2000

Hyperhomocystinemia in patients with nonarteritic anterior ischemic optic neuropathy, central retinal artery occlusion, and central retinal vein occlusion.

OBJECTIVE: This study aimed to determine the prevalence of hyperhomocystinemia among patients with nonarteritic anterior ischemic optic neuropathy (NAION), central retinal artery occlusion (CRAO), or central retinal vein occlusion (CRVO). DESIGN: Retrospective, case-control study. PARTICIPANTS: The study cohort consisted of 74 consecutive patients with NAION, CRAO, or CRVO who were examined at the Retina or Neuro-ophthalmological Unit of the Tel-Aviv Sourasky Medical Center from 1998 through 1999. The control group consisted of 81 consecutive patients of similar gender and age with no history of these pathologic conditions. MAIN OUTCOME MEASURES: Plasma homocystine levels of all study participants were obtained. RESULTS: Eighteen of 40 patients (45%) with NAION and eight of 13 patients (61.5%) with CRAO had hyperhomocystinemia compared with three of 21 (14.3%) in the CRVO group (P < 0.001) and eight (9.8%) in the control group (P < 0.0001). Hypertension and ischemic heart disease were significantly more prevalent in the NAION patients with elevated plasma homocystine. CONCLUSIONS: Our findings suggest that hyperhomocystinemia is a risk factor for NAION and CRAO.

Aged↗
PubMed1980

Central retinal artery occlusion and retinal tolerance time.

Transient central retinal artery occlusion (CRAO) was produced in 63 eyes of rhesus monkeys by lateral orbitotomy and temporary clamping of the central retinal artery (CRA) for between 15 and 270 minutes. Thirty-three eyes were examined at regular intervals for 12 to 22 weeks. Color fundus photography, fluorescein fundus angiography, electroretinography (ERG) and visual evoked response (VER) were performed before and during clamping of the CRA as well as periodically after unclamping. All the eyes were examined by light and/or electron microscopy. This study revealed that the retina suffered irreparable damage after ischemia of 105 minutes, but recovered well after ischemia of 97 minutes. As a general rule, the monkey retina can tolerate up to 100 minutes of ischemia but not more.

Animals↗
PubMed1990

[Lectin histochemical studies of retinal pigment epithelium in retinal detachment].

The retinal pigment epithelium (RPE) exhibits a broad spectrum of morphological changes under pathological conditions. Since RPE cells cannot be immunocytochemically characterized with certainty, lectin histochemical investigations were performed to study the lectin binding pattern of different morphological RPE variants in human globes. Normal RPE with attached retinas was compared to reactive changes in RPE following retinal detachment. Lectin binding sites were visualized by a modified PAP technique performed on paraffin-embedded tissue sections. Eight lectins of different sugar affinity (Con A, WGA, PNA, RCA 1, SBA, UEA 1, DBA, LPA) were tested for binding sites on the RPE. Both normal and reactively changed RPE possess receptors for Con A, WGA, PNA, and RCA 1. Modifications in the lectin binding pattern occurred simultaneously with the morphological changes within the RPE cells. RPE cells which form a monolayer on Bruch's membrane mainly have lectin binding sites in their apical portions. Proliferating and migrating RPE cells, especially RPE macrophages, which have withdrawn from the basal cell layer were found to contain lectin binding sites dispersed over the entire cytoplasm. RPE macrophages exhibited additional binding sites for the lectin SBA. These results indicate that RPE cell variants can be designated by means of their specific combination of lectin binding sites for Con A WGA, PNA, and RCA 1 not found on other cell types in the retina.

Humans↗
PubMed1999

Coincidence of cytomegalovirus retinitis and central retinal vein occlusion in a patient with hemophilia B and AIDS.

A 37-year-old man with hemophilia B, acquired immunodeficiency syndrome, and a unilateral cytomegalovirus retinitis developed a central retinal vein occlusion. This vascular complication occurred despite effective antiviral drug treatment with improvement of the fundus and despite decreased blood coagulability due to hemophilia B. Additional analyses of thrombophilic parameters did not reveal hints of systemic thrombophilia, suggesting that toxic and inflammatory effects of cytomegalovirus itself were responsible for the ophthalmologic aggravation.

AIDS-Related Opportunistic Infections↗
PubMed2001

Gene replacement therapy in the retinal degeneration slow (rds) mouse: the effect on retinal degeneration following partial transduction of the retina.

The retinal degeneration slow (rds or Prph2(Rd2/Rd2)) mouse, a model of recessive retinitis pigmentosa, lacks a functional gene encoding peripherin 2. This membrane glycoprotein is required for the formation of photoreceptor outer segment discs. The striking feature of the rds mouse is the complete failure to develop outer segments. We have previously examined the short-term effect of gene replacement therapy using an adeno-associated (AAV) vector and demonstrated induction of outer segments and improvement of photoreceptor function. Here we have extended our analysis and have demonstrated that the potential for ultrastructural improvement is dependent upon the age at which animals are treated, but the effect of a single injection on photoreceptor ultrastructure may be long-term. However, there was no significant effect on photoreceptor cell loss, irrespective of the date of administration, despite the improvements in morphology and function. Our investigation excluded procedure-related damage, vector toxicity and immune responses as major factors which might counteract the benefits of photoreceptor restoration, but suggested that transgene over-expression is of significance. These findings suggest that successful gene therapy in patients with photoreceptor defects may ultimately depend upon intervention in early stages of disease and upon accurate control of transgene expression.

Animals↗
PubMed2004

Application of magnetically isolated rat retinal vascular endothelial cells for the determination of transporter gene expression levels at the inner blood-retinal barrier.

The purpose of the present study was to quantify transporter gene levels at the inner blood-retinal barrier (inner BRB) using a combination of magnetic isolation method for rat retinal vascular endothelial cells (RVEC) and real-time quantitative PCR analysis. The transcript levels of CD31, Tie-2, claudin-5, occludin, Jam-1, mdr1a, oatp2, and oatp14 in the RVEC fraction were more than 100-fold greater than those in the non-RVEC fraction, suggesting that these genes are predominantly expressed at the inner BRB. The transcript levels of GLUT1 and MCT1 in the RVEC fraction were the most abundant in the respective transporter family, suggesting that GLUT1 and MCT1 play a predominant role in d-glucose and monocarboxylate transport, respectively, at the inner BRB. In conclusion, application of magnetically isolated RVEC is able to determine transporter gene levels at the inner BRB thereby increasing our understanding of inner BRB functions at a molecular level.

Animals↗
PubMedDate not supplied

Retinal ischaemia and relative afferent pupil defects in central retinal vein occlusion.

A consecutive series of 40 patients were assessed for relative afferent pupil defects and retinal ischaemia by fluorescein angiography. A strong correlation was found between density of afferent defect and area of retinal non-perfusion. There was an increasing incidence of rubeosis iridis with more severe grades of afferent defects or ischaemia.

Afferent Pathways↗
PubMed2003

Role of MCP-1 and MIP-1alpha in retinal neovascularization during postischemic inflammation in a mouse model of retinal neovascularization.

Macrophages are important participants in neovascularization. This study was designed to examine the role of the monocyte/macrophage chemotactic proteins, monocyte chemotactic protein-1 (MCP-1), and macrophage inflammatory protein-1alpha (MIP-1alpha) in a mouse model of oxygen-induced ischemic retinopathy and to determine whether the morphology and distribution of macrophages/microglia are concomitantly altered. The MCP-1, MIP-1alpha mRNA levels increased at 3 h after ischemia. MCP-1, MIP-1alpha, and vascular endothelial growth factor protein levels were also increased markedly and were maximal on days 1, 0.5, and 1, respectively, after ischemia. In situ hybridization showed that MCP-1 and MIP-1alpha were localized in the hypoxic inner retina. Immunostaining demonstrated that the macrophages/microglia in the retina had morphological changes with enlarged processes, and some were closely associated with neovascular tufts at postnatal day 17. Coadministration of the neutralizing antibodies against MCP-1 and MIP-1alpha inhibited retinal neovascularization by 30%. Our data suggest that MCP-1 and MIP-1alpha are involved in the induction of retinal neovascularization and play a role in the inflammation induced by the ischemic retinopathy, possibly by modulating or attracting macrophages/microglia.

Animals↗
PubMed2006

Stable rhodopsin/arrestin complex leads to retinal degeneration in a transgenic mouse model of autosomal dominant retinitis pigmentosa.

Over 100 rhodopsin mutation alleles have been associated with autosomal dominant retinitis pigmentosa (ADRP). These mutations appear to cause photoreceptor cell death through diverse molecular mechanisms. We show that K296E, a rhodopsin mutation associated with ADRP, forms a stable complex with arrestin that is toxic to mouse rod photoreceptors. This cell death pathway appears to be conserved from flies to mammals. A genetics approach to eliminate arrestin unmasked the constitutive activity of K296E and caused photoreceptor cell death through a transducin-dependent mechanism that is similar to light damage. Expressing K296E in the arrestin/transducin double knock-out background prevented transducin signaling and led to substantially improved retinal morphology but did not fully prevent cell death caused by K296E. The adverse effect of K296E in the arrestin/transducin knock-out background can be mimicked by constant exposure to low light. Furthermore, we found that arrestin binding causes K296E to mislocalize to the wrong cellular compartment. Accumulation of stable rhodopsin/arrestin complex in the inner segment may be an important mechanism for triggering the cell death pathway in the mammalian photoreceptor cell.

Animals↗
PubMedDate not supplied

Combined hamartoma of the retina and retinal pigment epithelium with full thickness retinal hole and without retinoschisis.

Combined hamartoma of the retina and retinal pigment epithelium has been described as a rare, benign tumor formed by an overgrowth of several constituents of the retina such as the retinal pigment epithelial cells, vascular elements, and glial components.1 Despite its varied clinical appearance it is important to recognize this tumor as it is known to simulate intraocular malignancies like retinoblastoma and choroidal melanoma.

Adult↗
PubMed1975

Acute onset of central retinal vein occlusion and retinal detachment.

The simultaneous occurrence of a central retinal vein occlusion and retinal detachment has not been previously reported. Although both are well recognized entities with characteristic appearances, their simultaneous acute onset led to a misdiagnosis in our case report. The need for a complete eye examination in the face of obvious pathology is stressed.

Humans↗
PubMed2002

[Application of confocal scanning laser Doppler retinal flowmetry in the measurement of fundus blood flow parameters after retinal detachment surgery].

OBJECTIVE: To discuss the influence of retinal detachment (RD) surgery on the blood flow of retina and optic nerve head. METHODS: Heidelberg Retina Flowmeter (HRF) was used to measure the blood flow of retina and optic nerve head in 62 eyes of 62 patients with postoperative rhegmatogenous RD surgery, including 34 eyes having undertaken vitreoretinal (VR) surgery and 28 eyes, scleral buckling (SB) surgery. Operative methods included scleral encircling procedure, cryotherapy, lensectomy, vitrectomy, perfluorodeclin liquid application, endolaser and C(2)F(6) gas or silicone oil tamponade. RESULTS: The blood flow volume (VOL), blood flow velocity (FLW) and the erythrocyte flow velocity (VEL) of fundus in the postoperative RD eyes were reduced in the comparison with those of the fellow control eyes. The VEL of temporal and nasal papillary disk rim had significant differences (P < 0.05). The VOL, FLW and VEL of the papillary vessel, VOL and FLW of temporal and nasal papillary disk rim, VOL of temporal and nasal juxtapapillary retina in the operative eyes were lower than those of the fellow eyes (P < 0.01). In the comparison between the eyes having undertaken VR surgery and the eyes undertaken SB surgery, the VOL, FLW and VEL of VR surgery were reduced more than those of SB surgery. The VEL of temporal and nasal papillary disk rim and nasal juxtapapillary retina and FLW of temporal juxtapapillary retina had significant differences (P < 0.05). VOL, FLW and VEL of silicone oil tamponade eyes were reduced more than those in the operative eyes without silicone oil tamponade. VOL of nasal papillary disk rim and juxtapapillary retina had significant differences (P < 0.05). VOL and VEL of temporal papillary disk rim, VOL of temporal juxtapapillary retina had very significant differences (P < 0.01). CONCLUSIONS: VR surgery and SB surgery of RD influence papillary and retinal VOL, FLW, VEL. The influence of VR surgery on the fundus blood flow is more significant than that of SB surgery. The silicone oil tamponade also influences the VOL and VEL of the fundus.

Adolescent↗