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PubMed1996

Remodelling of choroidal circulation in carotid cavernous sinus fistula.

BACKGROUND: Carotid cavernous sinus fistula may induce drastic changes in choroidal circulation secondary to elevated orbital venous pressure. CASES AND METHODS: Three patients affected by spontaneous carotid cavernous sinus fistula were studied for 3-15 months. The angioarchitecture and hemodynamics of the choroid were evaluated repeatedly by indocyanine green angiography using a montage panoramic technique. RESULTS: Choroidal vessels underwent drastic restructuring including patchy nonperfusion of the choriocapillaris, attenuation of vortex veins, preferential venous dilatations, and drainage into outflow channels near the optic disc or into anterior ciliary veins. CONCLUSIONS: Choroidal veins were very versatile in remodelling their structure and hemodynamics after sustained elevation of orbital venous pressure. The presence of numerous anastomoses between choroidal veins appeared to be a major underlying cause of this versatility. The observed remodelling of choroidal vessels seemed to be guided by the principle that the venous blood flowed toward sites of lesser pressure resistance.

Aged↗
PubMed1998

Morphometric characteristics of traumatic choroidal ruptures associated with neovascularization.

PURPOSE: To define the morphometric characteristics of indirect choroidal ruptures associated with choroidal neovascularization (CNV). METHODS: A total of 79 eyes that had sustained traumatic indirect choroidal ruptures was studied retrospectively. Color pictures of the fundus and fluorescein angiograms were available in all cases, and patients were followed for at least 1 year. Eyes that were free of CNV constituted Group I; eyes that developed CNV constituted Group II. Baseline characteristics of both groups, including age, sex, and visual acuity, were recorded. Distance of indirect choroidal ruptures from the center of the fovea and morphometric characteristics of the ruptures were calculated using image analysis software (Image 1.60; National Institutes of Health, Bethesda, MD). RESULTS: A total of 63 eyes (79.7%) free of CNV was included in Group I and 16 eyes (20.3%) that developed CNV were included in Group II. Morphometric analysis showed a greater distance between the indirect choroidal rupture and the center of the fovea in Group I than in Group II (median, 1480 microm versus 612 microm; P = 0.009). In addition, the length of the rupture was shorter in Group I than in Group II (median, 3054 microm versus 4504 microm; P = 0.03). CONCLUSIONS: Two significant factors associated with the presence of CNV in case of traumatic choroidal rupture were identified and quantified: the proximity of the rupture to the center of the fovea and the length of the rupture. Both should be considered as risk factors for the development of CNV and monitoring should take them into account.

Adolescent↗
PubMed2002

Photodynamic therapy for choroidal neovascularization: a review.

PURPOSE: To review the biophysical basis and current state of therapy for photodynamic closure of subfoveal choroidal neovascularization in the eye. METHODS: A review of the literature is included, which encompasses the chemical structure, biophysical mechanism of action, range of available agents, status of clinical trials, clinical indications, results of treatments, complications, and future directions. RESULTS: Photodynamic therapy has been shown to be effective in closing both experimental choroidal neovascularization in animal models as well as subfoveal choroidal neovascularization in humans. The therapy results in temporary closure of choroidal new vessels for a period of approximately 1 to 4 weeks. By 12 weeks, most patients have reperfusion or reproliferation of choroidal new vessels resulting in the need for retreatment to achieve continued closure and visual stabilization. Differences exist in the quantum yield, clinical efficiency, and light and sensitizer dose requirements between different classes of agents. Further clinical trials will be required to determine the optimal form of therapy, with verteporfin (Visudyne) as the only currently approved agent. Other agents, including tin etiopurpurin (Purlytin) and motexafin lutetium (Optrin), are currently undergoing phase III, and phase II trials, respectively. CONCLUSIONS: Photodynamic therapy is a promising treatment modality shown to be effective in achieving closure and stabilization of vision loss compared with placebo control in eyes with subfoveal choroidal neovascularization.

Choroidal Neovascularization↗
PubMed1999

Transpupillary thermotherapy for choroidal melanoma.

The management of choroidal melanomas depends on many factors, most importantly, tumor size and location. Small choroidal melanoma in the posterior fundus is amenable to treatment options such as enucleation, radiotherapy, laser photocoagulation, and transpupillary thermotherapy or a combination of these methods. Transpupillary thermotherapy is a technique of tumor heating by infrared radiation delivered through the pupil into the tumor. This method causes dramatic tumor necrosis in choroidal melanomas up to 4 mm in thickness. With properly selected small choroidal melanomas, tumor control is approximately 94%. The heat induces cellular damage at the site of treatment with few remote side effects; therefore, complications are generally limited to the site of treatment and include retinal vascular obstruction (23%), retinal traction (20%), retinal neovascularization (6%), and retinal hole with detachment (< 1%). Tumors located temporal to the foveola demonstrate a statistically higher risk for retinal traction than those located in other quadrants. Tumors near the optic disk demonstrate a higher incidence of retinal neovascularization due to heat-induced obstruction of a major retinal vascular arcade. Overall, vision preservation is satisfactory after thermotherapy for choroidal melanoma, with more than 50% of patients maintaining the same or better vision after treatment, depending primarily on tumor location. In summary, small choroidal melanomas can be controlled with transpupillary thermotherapy, especially those near the optic disk and foveola in areas that are otherwise difficult to irradiate. Longer follow-up is necessary to assess for local recurrence and the impact of treatment on life prognosis.

Animals↗
PubMed2002

The effect of losartan potassium on choroidal hemodynamics in healthy subjects.

PURPOSE: To investigate the choroidal hemodynamic effects of losartan potassium, a specific angiotensin II subtype AT1 receptor antagonist. METHODS: In this prospective, randomized, observer-masked, open-label placebo-controlled (lactose), two-period crossover study, the choroidal hemodynamic effects of a single oral 50-mg dose of losartan potassium were evaluated in 12 healthy subjects using choroidal laser Doppler flowmetry. RESULTS: Perfusion pressure and the choroidal laser Doppler flowmetry parameters velocity, volume, and flux did not vary significantly compared with placebo (P = 0.33, 0.31, 0.74, and 0.61, respectively). Correcting choroidal laser Doppler flowmetry parameters for perfusion pressure in a covariance analysis did not change these results. CONCLUSION: A single oral 50-mg dose of the angiotensin II AT1 receptor antagonist losartan potassium given does not disturb the homeostasis of ocular perfusion pressure or choroidal blood flow in young healthy subjects.

Administration, Oral↗
PubMed2005

Choroidal melanoma with massive extrascleral extension in a young black man.

The reported incidence of choroidal melanoma is low among the general population and is especially low among blacks. Choroidal melanoma is seen most commonly in whites in the sixth to seventh decades. The tumor is complicated by orbital invasion in only a small percentage of cases. This report describes the case of a 38-year-old black man diagnosed with a choroidal melanoma of the right eye. The tumor exhibited extensive orbital invasion. Primary or metastatic disease elsewhere in the body was ruled out, and the patient underwent an eyelid-sparing orbital exenteration. Histopathologic examination of the orbital specimen confirmed the diagnosis of spindle cell-type choroidal melanoma. Orbital invasion by a primary choroidal melanoma in a black person under the age of 40 is highly unusual. To our knowledge, this represents the youngest reported case of choroidal melanoma with extrascleral extension in a black patient. Ophthalmologists should consider the possibility of this potentially deadly tumor, even in young, black patients.

Adult↗
PubMed2006

Prognostic implications of atypical histologic features in choroid plexus papilloma.

The prognostic significance of atypical histologic features in choroid plexus tumors remains uncertain. Therefore, a series of 164 choroid plexus tumors was evaluated for the presence of atypical histologic features, including mitotic activity, increased cellularity, nuclear pleomorphism, blurring of papillary growth pattern, and necrosis. The impact of histopathologic and clinical features on the probability of recurrence and survival was investigated. Twenty-four tumors displaying frank signs of malignancy were diagnosed as choroid plexus carcinoma according to World Health Organization criteria. Of 124 choroid plexus papillomas that had not received adjuvant treatment, 46 tumors (37%) displayed at least one atypical feature, including increased cellularity (n = 25 [20%]), mitotic activity (> or =2 mitoses per 10 high-power fields; n = 19 [15%]), nuclear pleomorphism (n = 16 [13%]), solid growth (n = 15 [12%]), and necrosis (n = 5 [4%]). Only one tumor-related death, but 10 recurrences, were observed on a mean observation time of 58 months. On univariate analysis, incomplete surgical resection (p = 0.03) and mitotic activity (p < 0.001) were the only clinicopathologic factors associated with recurrence. Using a multivariate model, an independent effect of mitotic activity on the probability of recurrence could be confirmed (p = 0.001). Because mitotic activity is the sole atypical histologic feature independently associated with recurrence, we propose to define atypical choroid plexus papilloma by mitotic activity (> or =2 mitoses per 10 high-power fields) corresponding to World Health Organization grade II, thus adjoining other intermediate tumor entities associated with increased mitotic activity such as atypical meningioma. Close follow up of patients harboring atypical choroid plexus papillomas may be warranted.

Adult↗
PubMed1990

Subepithelial basement membrane deposition and intermediate filament expression in choroid plexus neoplasms and ependymomas.

The pattern of basement membrane deposition was investigated in benign and malignant choroid plexus tumours using an immunocytochemical method to detect laminin, an intrinsic basement membrane component. The results were compared with intracranial ependymomas and myxopapillary ependymomas of the filum terminale. Expression of the intermediate filaments cytokeratin and glial fibrillar acidic protein (GFAP) and the epithelial marker carcino-embroyonic antigen (CEA) was also assessed. Laminin was detected in a subepithelial location in all the choroid plexus tumours but in none of the ependymomas, although basement membrane fragmentation was seen in the choroid plexus carcinomas. In contrast, GFAP was present in all the types of tumour examined. Cytokeratin (as detected by CAM 5.2) was present in all the choroid plexus lesions and also in the ependymomas arising in the spinal canal. CEA was not detected. We conclude that immunostaining for laminin assists distinction between choroid plexus tumors and papillary ependymomas and between benign and malignant choroid plexus tumours.

Basement Membrane↗
PubMed1998

Nocardia choroidal abscess in a patient with systemic lupus erythematosus.

PURPOSE: Nocardia asteroides, a respiratory saprophyte in humans, may cause localized infection of the lungs in debilitated or immunosuppressed individuals. Haematogenous spread to the eye via the choroidal circulation may result in choroidal abscess formation. METHOD: We report the development of a choroidal abscess in the left eye of a woman treated with steroids and cyclophosphamide for systemic lupus erythematosus. Haematogenous spread of N. asteroides from a localized infection of the lung (empyema) is thought to have been the cause of the choroidal abscess. RESULTS: Surgical drainage of the empyema combined with intravenously administered antibiotics resulted in resolution of the choroidal abscess and improvement of vision. CONCLUSIONS: A choroidal abscess, caused by haematogenous spread of N. asteroides, may respond to appropriate systemic antibiotic treatment alone and not require ocular treatment.

Abscess↗
PubMed1982

Active transport of nicotine by the isolated choroid plexus in vitro.

In vitro, the transport of [14C]nicotine into the isolated choroid plexus, the anatomical locus of the blood--CSF barrier, was studied. The isolated rabbit choroid plexus accumulated [14C]nicotine by two processes: an active saturable transport process and a nonsaturable process. The [14C]nicotine accumulation process by choroid plexus was not due to binding or intracellular metabolism of the [14C]nicotine. The [14C]nicotine accumulation process in isolated choroid plexus was inhibited by weak bases, including tolazoline and lidocaine, but not by the weak acid probenecid. The accumulation process was decreased 60% by iodoacetate and dinitrophenol and by low temperatures. These results are consistent with previous autoradiographic evidence showing the choroid plexus concentrated [14C]nicotine in vivo, and suggest that the choroid plexus may transfer nicotine between blood and CSF in vivo.

Animals↗
PubMed1984

Accumulation of pantothenic acid by the isolated choroid plexus and brain slices in vitro.

In vitro, the transport of [14C]pantothenic acid into and from the isolated rabbit choroid plexus, an anatomical locus of the blood-CSF barrier, and brain slices was studied. The choroid plexus accumulated [14C]pantothenic acid from the medium against a concentration gradient, although at low concentrations (less than 1 microM) there was substantial intracellular phosphorylation and binding of the [14C]pantothenic acid. The saturable accumulation process in choroid plexus was inhibited by probenecid and caproic acid but not by nicotinic acid or by weak bases. The accumulation process was markedly inhibited by N-ethylmaleimide, poly-L-lysine (which blocks sodium transport), and low temperatures. [14C]Pantothenic acid was readily released from choroid plexus by a temperature-dependent process. Brain slices also accumulated and, at low concentrations, phosphorylated [14C]pantothenic acid from the medium by a temperature-, probenecid-, and N-ethylmaleimide-sensitive saturable process. However, unlike choroid plexus, brain slices did not concentrate free pantothenic acid and [14C]pantothenic acid accumulation was not sensitive to poly-L-lysine. [14C]Pantothenic acid was readily released from brain slices by a temperature-sensitive process. These results are consistent with the view that [14C]pantothenic acid enters the isolated choroid plexus and brain slices by active transport and facilitated diffusion, respectively.

Animals↗
PubMed1984

Specificity and sodium dependence of the active nucleoside transport system in choroid plexus.

The transport of [3H]deoxyuridine by the active nucleoside transport system into the isolated rabbit choroid plexus was measured in vitro under various conditions. Choroid plexuses were incubated in artificial CSF containing 1 microM [3H]deoxyuridine and 1 microM nitrobenzylthioinosine for 5 min under 95% O2-5% CO2 at 37 degrees C and the accumulation of [3H]deoxyuridine measured. Nitrobenzylthioinosine was added to the artificial CSF at a concentration (1 microM) that did not inhibit the active nucleoside transport system but did inhibit the separate, saturable nucleoside efflux system. The active transport of deoxyuridine into the choroid plexus depended on Na+ in the medium, as ouabain, substitution of Li+ and choline for Na+, and poly-L-lysine all inhibited deoxyuridine transport. Thiocyanate in place of chloride and penetrating sulfhydryl reagents also inhibited the active transport of deoxyuridine into choroid plexus. The active transport of deoxyuridine into choroid plexus, which is inhibited by naturally occurring ribo- and deoxyribonucleosides (IC50 = 7-21 microM), was not inhibited (IC50 much greater than 150 microM) by nucleosides with certain alterations on the 2', 3', or 5' positions in D-ribose or 2-deoxy-D-ribose (e.g., adenine arabinoside, 3'-deoxyadenosine, xylosyladenosine); or the pyrimidine or purine rings (e.g., 6-azauridine, xanthosine, 7-methylinosine, or 8-bromoadenosine). Other analogues were effective (IC50 = 8-26 microM; e.g., 5-substituted pyrimidine nucleosides, 7-deazaadenosine, 6-mercaptoguanosine) or less effective (IC50 = 46-145 microM; e.g., 5-azacytidine, 3-deazauridine) inhibitors of deoxyuridine transport into the isolated choroid plexus.

Animals↗
PubMed1995

Differential diagnosis of choroidal melanomas and nevi using scanning laser ophthalmoscopical indocyanine green angiography.

Fluorescein angiography is one of several standard ancillary diagnostic techniques in the evaluation of suspected malignant choroidal melanoma. Indocyanine green choroidal angiography has improved visibility of the choroidal circulation in comparison with fluorescein angiography. Studies concerning the use of indocyanine green angiography in the differentiation between nevi and melanomas have been few and the results inconclusive. A case of a choroidal melanoma (verified by histopathological examination) and a nevus in the same eye is documented by fluorescein and indocyanine green choroidal angiography performed by scanning laser ophthalmoscopy. This modality may be considered in the evaluation of a suspected malignant choroidal melanoma.

Aged↗
PubMed2006

Alcohol linked to enhanced angiogenesis in rat model of choroidal neovascularization.

One of the pathologic complications of exudative (i.e. wet-type) age-related macular degeneration (AMD) is choroidal neovascularization (CNV). The aim of this study was to investigate whether chronic and heavy alcohol consumption influenced the development of CNV in a rat model. The oxidative metabolism of alcohol is minimal or absent in the eye, so that ethanol is metabolized via a nonoxidative pathway to form fatty acid ethyl esters (FAEE). Fatty acid ethyl ester synthase (FAEES) was purified from the choroid of Brown Norway (BN) rats. The purified protein was 60 kDa in size and the antibody raised against this protein showed a single band on western blot. BN rats on a regular diet were fed alcohol for 10 weeks. Control rats were fed water with a regular diet and pair-fed control rats were fed regular diet, water and glucose. We found that FAEES activity was increased 4.0-fold in the choroid of alcohol-treated rats compared with controls. The amount of ethyl esters produced in the choroid of 10 week alcohol-fed rats was 7.4-fold more than rats fed alcohol for 1 week. The increased accumulation of ethyl esters was associated with a 3.0-fold increased expression of cyclin E and cyclin E/CDK2; however, the level of the cyclin kinase inhibitor, p27Kip, did not change. The increased accumulation of ethyl esters was also associated with 3.0-fold decreased expression of APN in the choroid. We also found that the size of CNV increased by 28% in alcohol-fed rats. Thus, our study showed that chronic, heavy alcohol intake was associated with both an increased accumulation of ethyl esters in the choroid and an exacerbation of the CNV induced by laser treatment. These results may provide insight into the link between heavy alcohol consumption and exudative AMD.

Acyltransferases↗
PubMed1979

Retinal and choroidal contribution to retinal metabolism in vivo. A study in pigs.

The glucose metabolism of the retina was studied in vivo, by determining glucose, oxygen and lactate a-v differences for choroidal and retinal blood in pigs at different levels of intraocular pressure. At normal intraocular pressure the choroidal a-v differences were 0.07 and 0.11 mmol/l for glucose and oxygen respectively. The corresponding figures for the retina were 0.44 and 2.15. At increased levels of intraocular pressure the choroidal and retinal glucose and choroidal oxygen a-v differences increased, thus at least partly compensating for reduced blood flow. A major part of the oxygen and glucose consumed by the retina was delivered by the choroid. The total amount of oxygen extracted from choroidal and retinal blood could only account for complete oxidation of 37% of the extracted glucose. The results obtained in determinations of lactate a-v differences indicate that part of the remaining glucose is used for anaerobic glycolysis.

Animals↗
PubMed1992

Duplex and color Doppler ultrasound in the differential diagnosis of choroidal tumors.

There is paucity of data on the value of neovascular blood flow measurements in the differential diagnosis of human choroidal tumors, mainly due to difficulties in quantitating tumor vascularity in vivo. Color Doppler imaging and Duplex ultrasound, the combination of B-mode ultrasound and pulse Doppler analysis, were used to quantify tumor blood flow in 103 untreated tumors of the choroid. Pulsatile blood flow was detected at the tumor base of 62 choroidal melanomas (tumor height (TH) 3.1-11.7 mm) with a mean peak systolic frequency (MPSF) of 0.98 kHz (range 0.3-2.7 kHz). Compared to melanomas pulsatile neovascular flow in choroidal metastases (TH 2.1-6.5 mm, n = 12) was significantly higher (MPSF 1.87 kHz, range 0.8-3.5 kHz). No Doppler signals were elicited from age-related macular degeneration (n = 9), choroidal nevus (TH 1.5-2.1 mm, n = 18) and choroidal osteoma (n = 2). The results indicate that the quantitative measurement of tumor blood flow by duplex and color Doppler ultrasound may serve as a new diagnostic tool in the evaluation of intraocular tumors.

Adult↗
PubMed1974

Active transport of sodium and potassium by the choroid plexus of the rat.

1. Choroid plexus from the lateral ventricle in the adult rat was found to contain approximately 54 m-equiv Na(+) and 89 m-equiv K(+) per kg wet tissue.2. The total water (79%), the extracellular space (21%) and the red blood cell volume (8-9%) in choroid plexus were quantified separately by analysing the distribution of [(14)C]antipyrine, [(14)C]inulin and (51)Cr-tagged erythrocytes, respectively, between this tissue and plasma water.3. The tissue electrolyte data together with the compartmental (space) data were used to calculate an average concentration of Na(+) (39 m-equiv/kg cell H(2)O) and of K(+) (144) in the choroid cell.4. Under various experimental conditions known to stimulate or inhibit the Na(+)-K(+) transport system in other tissues, there were significant changes (10-40 m-equiv/kg cell H(2)O) in the concentrations of both these cations in the plexus epithelial cells.5. Choroid cell K(+) was not independent of the concentration of K(+) in plasma since substantial fluctuations in cell K(+) occurred in rats rendered either hypo- or hyperkalaemic; also, the choroid cell apparently cannot maintain a constant gradient between itself and c.s.f. in the face of kalaemic disturbances.6. Evidence is offered to support the hypothesis that the choroid plexus of the lateral ventricle has a Na(+)-K(+) pump, the operation of which contributes to the maintenance of K(+) homoeostasis in the C.N.S.

Animals↗
PubMed2002

Inward-rectifying anion channels are expressed in the epithelial cells of choroid plexus isolated from ClC-2 'knock-out' mice.

Choroid plexus epithelial cells express inward-rectifying anion channels which have a high HCO(3)(-) permeability. These channels are thought to have an important role in the secretion of cerebrospinal fluid. The possible relationship between these channels and the ClC-2 Cl(-) channel was investigated in the present study. RT-PCR, using specific ClC-2 primers, amplified a 238 bp fragment of mRNA from rat choroid plexus, which was 99 % identical to the 5' sequence of rat ClC-2. A 2005 bp clone was isolated from a rat choroid plexus cDNA library using a probe for ClC-2. The clone showed greater than 99 % identity with the sequence of rat ClC-2. Inward-rectifying anion channels were observed in whole-cell recordings of choroid plexus epithelial cells isolated from ClC-2 knock-out mice. The mean inward conductance was 19.6 plus minus 3.6 nS (n = 8) in controls (3 heterozygote animals), and 22.5 plus minus 3.1 nS (n = 10) in three knock-out animals. The relative permeability of the conductances to I(-) and Cl(-) (P(I) : P(Cl)) was determined. I(-) was more permeant than Cl(-) in both heterozygotes (P(I):P(Cl) = 4.0 +/- 0.9, n = 3) and knock-out animals (P(I) : P(Cl) = 4.1 +/- 1.4, n = 3). These results indicate that rat choroid plexus expresses the ClC-2 variant that was originally reported in other tissues. ClC-2 does not contribute significantly to inward-rectifying anion conductance in mouse choroid plexus, which must therefore express a novel inward-rectifying anion channel.

Algorithms↗