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PubMed1991

Choroidal vasculitis in acute posterior multifocal placoid pigment epitheliopathy.

A 24-year-old Caucasian female presented with acute posterior multifocal placoid pigment epitheliopathy (APMPPE) and associated infiltration round some of the larger choroidal blood vessels. This infiltration dissipated as the patient's clinical condition improved and did not induce any permanent alteration of the overlying retinal pigment epithelium. We suggest that the infiltration round the choroidal vessels was due to a choroidal vasculitis. The finding of choroidal inflammation in this case lends support to the hypothesis that choroidal vasculitis is an underlying pathological process in APMPPE.

Adult↗
PubMed2001

Intraocular pressure measurement at the choroid surface: a feasibility study with implications for implantable microsystems.

AIMS: To demonstrate that a sensor, which is inserted through the sclera and placed in intimate contact with the choroid, can reliably detect changes in the intraocular pressure (IOP). METHODS: A manometer was used to control the IOP of three cadaver eyes in steps of 7 mm Hg. A piezoresistive pressure sensor was used to measure the pressure at the choroid through a 2.5 mm diameter hole that was surgically removed from the sclera. Data were collected for two configurations; with the sensor: (i) rigidly attached to a miniature positioning stage, and (ii) sutured to the sclera. RESULTS: Both configurations accurately tracked the manometer pressure from 10 mm Hg to 47 mm Hg. For the fixed sensor cases, the average difference between the pressure measured at the choroid and in the anterior chamber was 0.8 mm Hg for the three eyes. For the sutured sensor case, the average difference was 2.1 mm Hg-although a significant portion of this was attributed to an initial offset. The standard deviations at each pressure level for all of the choroid measurements were under 1.0 mm Hg. CONCLUSIONS: Small changes in IOP can be accurately measured by a sensor in contact with the surface of the choroid, for both a fixed sensor configuration and for a sensor sutured to the sclera. These results are the first step in the realisation of a surgically implantable microsensor to monitor IOP for patients suffering from low tension and other difficult to manage forms of glaucoma.

Choroid↗
PubMed1980

On the anatomic relation of choroid plexus to brain: a comparative study.

The size of choroid plexuses and cerebral ventricles relative to brain varies widely among vertebrates. The functional significance of this variability has attracted little attention since Herrick's original proposal that large choroid plexuses might enhance oxygen delivery to the brain and therefore be of adaptive value in the transition of vertebrates from water to air breathing. We compared choroid plexus and brain weight or ventricular and brain volume in 40 species from nine vertebrate groups. Both choroid plexus weight and ventricular volume were unrelated to brain size. Plexus weight ranged from 0 to 5.2% of brain weight and ventricular volume from 0.9 to 132% of brain volume. Amid this diversity the dipnoans, chondrosteans, holosteans, amphibians, and crossopterygian examined in this study are exceptional in uniformly having large plexuses. The adaptive significance of large choroid plexuses may lie in the presence of specific homeostatic mechanisms and their role in the response to the increases in PCO2 that accompany the transition to air breathing.

Animals↗
PubMed1990

Acetazolamide and insulin alter choroid plexus epithelial cell [Na+], pH, and volume.

Agents that inhibit or stimulate Na+ transport were tested for their effects on the ionic composition and volume of the in vivo choroid plexus (CP) epithelium. Ketamine-anesthetized adult Sprague-Dawley rats treated 1 h with acetazolamide or insulin were analyzed for choroid cell [Na+]i, [HCO3-]i, and pHi (dimethadione method); for transmembrane Na+ and H+ gradients; and for the kinetics of penetration of 22Na from plasma to plexus epithelium to CSF. Acetazolamide (25 mg/kg) reduced [Na+]i by 5-10 mmol/l and substantially elevated [HCO3-]i and pHi; the concurrent 22Na uptake by the in vivo choroid plexus and CSF, as quantified by the transfer coefficient, Kin (ml.g-1.h-1), was curtailed by 55-60%. Such effects on Na+ transport and distribution are likely secondary to the alkalinization of pHi induced by carbonic anhydrase inhibition. Conversely, insulin (3 U/kg ip) stimulated Na+ transport, i.e., manifested as enhanced uptake of 22Na from plasma to choroid cell and increased [Na+]i. For various treatments altering the basolateral membrane H+ gradient, the regression analysis of the 22Na Kin vs. log [H+]i/[H+]ISF (where ISF is interstitial fluid) was significant at P less than 0.01. This is consistent with effects mediated by Na(+)-H+ exchange. K+ and Cl- redistribution phenomena were coincident with altered Na+ transport, as choroidal cells retained K+, Cl-, and H2O after acetazolamide but lost K+, Cl-, and H2O with insulin treatment. A model is presented relating alterations in CP Na+ transport, KCl content, and cell volume. Overall, the findings encourage the postulate for effects of these drugs on Na+ transport basolaterally, either indirectly by attenuating [H+]i/[H+]ISF (acetazolamide) or directly by accelerating Na+ transport (insulin).

Acetazolamide↗
PubMed1991

Kinetics of circulating vasopressin uptake by choroid plexus.

Uptake of circulating arginine vasopressin (AVP) by choroid plexus was studied by means of the in situ brain perfusion technique in anesthetized guinea pig and by means of single-circulation paired-tracer dilution technique in isolated perfused sheep choroid plexus. Kinetic analysis revealed saturable AVP uptake with Michaelis constant (Km) values of 32 +/- 4 and 31 +/- 5 nM and maximal saturable influx rate (Vmax) of 0.45 +/- 0.06 and 12.1 +/- 0.67 pmol.min-1.g-1 in guinea pig and sheep choroid plexus, respectively. The peptide fragments AVP-(1-8) and [pGlu4,Cyt6]AVP-(4-9), the amino acids L-phenylalanine, L-tyrosine, and 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid, and the aminopeptidase inhibitors Bestatin and bacitracin did not influence hormone kinetics. However, the V1 antagonist [(1-beta-mercapto-beta,beta-cyclo-pentamethylenepropionic acid)-O-methyl-Tyr2]AVP significantly inhibited AVP uptake with inhibitor constant (Ki) values of 0.19 +/- 0.03 (guinea pig) and 0.07 +/- 0.01 microM (sheep). The V2 agonist 1-desamino-8-D-AVP and pressinoic acid produced weak inhibitions only in guinea pig choroid plexus, and Ki/Km ratios indicated 220 and 310 times lower affinities than for AVP, respectively. It is suggested that the membrane mechanism responsible for AVP uptake in choroid plexus has a binding site with properties similar to those of V1 receptor.

Animals↗
PubMed1998

Choroidal coloboma in two members of a family.

A family with choroidal coloboma is reported. A 43-year-old Japanese woman with choroidal coloboma including the optic disk and extending to the inferior half of the fundus in both eyes had horizontal nystagmus, microcornea and mild cortical cataract in both eyes. Her 40-year-old younger sister had choroidal colobomas in both eyes and also a horizontal nystagmus, microcornea in both eyes and a mature cataract in the left eye. They had no systemic abnormalities. Their parents and 2 younger sisters showed neither ocular nor systemic abnormalities. Choroidal coloboma with iris coloboma has been reported frequently, but familial choroidal coloboma without involvement of the iris and with no systemic abnormalities is rare.

Adult↗
PubMed2002

Choroid plexectomy reduces neurosurgical intervention in patients with hydranencephaly.

INTRODUCTION: The removal of the choroid plexus from the lateral ventricles was attempted by Dandy in the early 20th century but later discarded as complications arose and other methods of cerebrospinal fluid (CSF) diversion were introduced. We compare our experience with a variation of this operation to CSF diversion in patients with hydranencephaly or near hydranencephaly. METHODS: The hospital and office charts of patients with a diagnosis of hydranencephaly were reviewed from the two institutions spanning the career of the senior author. Thirteen patients were identified, of whom 9 underwent CSF diversionary procedures (group A) and 4 underwent choroid plexectomy (group B). RESULTS: The mean number of reoperations (2 in group A, 0 in group B), neurosurgical readmissions (1.5 in group A, 0 in group B) and days of hospitalization related to neurosurgical readmissions (43.5 in group A, 0 in group B) were all less in patients who underwent choroid plexectomy. The total incidence of complications related to surgery was also lower in this group (7 in group A, 0 in group B). CONCLUSION: In our experience, choroid plexectomy in patients with hydranencephaly reduces the incidence of reoperation and readmission, the number of days of hospitalization related to the surgical procedure and the total number of complications in comparison to patients undergoing CSF diversion. Further neurosurgical intervention is minimized as is the financial burden from multiple emergency department visits and radiological procedures for shunt evaluation. Choroid plexectomy is a viable alternative to CSF diversion in patients with hydranencephaly and a rapidly enlarging head. It avoids the chronic issues and complications surrounding CSF diversion in this difficult group of patients.

Choroid Plexus↗
PubMedDate not supplied

Evaluation of the circulation in the retina, peripapillary choroid and optic disk in normal-tension glaucoma.

Computerized image analysis, including fluorescein angiography, was used to evaluate the retinal, choroidal and optic disk blood flow in 16 patients with normal-tension glaucoma (NTG) and to correlate this measurement with visual fields, retinal vessel width, optic disk pallor and blood pressure (BP). The angle of the ascending slope of the fluorescein dye curve was measured as an index of blood flow from the densitometric and time curves of the fluorescein angiograms in the optic disk, peripapillary choroid, retinal artery and vein for each quadrant. While the ascending slope as well as the retinal vessel width were most reduced in the inferior and nasal regions, the mean threshold was lowest in the superior and nasal quadrants. There were positive significant correlations between artery width and threshold value, between angles of slopes and pallor. In addition, systolic BP had a negative correlation with pallor, and diastolic BP had a positive one with slope in the choroid. These results indicated the probable association of a decrease in retinal, choroidal and optic disk blood flow in the inferior and nasal quadrants as well as vessel width in the inferior nasal quadrant with visual field loss in the superior quadrant, and also demonstrated an increasing blood flow for enlargement of pallor. A decrease in BP was found to be related to reduced blood flow in choroid and optic disk impairment.

Blood Circulation↗
PubMedDate not supplied

Retinal and choroidal vasculature in rats with spontaneous diabetes type 2 treated with the angiotensin-converting enzyme inhibitor cilazapril: corrosion cast and electron-microscopic study.

The long-term effects of the angiotensin-converting enzyme (ACE) inhibitor cilazapril on retinal and choroidal circulation in rats with spontaneous diabetes type 2 were assessed by corrosion casts, scanning electron microscopy (SEM) and transmission electron microscopy. One group of 20 male Otsuka Long-Evans Tokushima Fatty (OLETF) rats was treated with 10 mg/kg/day of cilazapril from 4 to 64 weeks of age, and 20 other OLETF rats received no treatment. A third group, 20 male Long-Evans Tokushima Otsuka (LETO) rats, served as age-matched controls. At regular intervals, the rats were weighed, and their blood glucose was measured. Before the experiment, their systolic blood pressure and total cholesterol level were determined. At 64 weeks of age, the OLETF rats weighed significantly less than the cilazapril-treated OLETF and the LETO rats (p < 0.0001). At the same age, 100% of the untreated OLETF rats had bilateral cataracts, while the lens was clear and no fundus abnormality was detected in the cilazapril-treated OLETF rats and the LETO rats. Cilazapril lowered systolic blood pressure to a nearly normal level, significantly prevented the increase in blood sugar and inhibited the increase in serum cholesterol in the OLETF rats throughout the treatment. In the 64-week-old OLETF rats without treatment, corrosion cast and SEM revealed diabetic retinal and choroidal vascular changes: tortuosity of the vessels, variations in caliber, narrowing of arteries, arterio-arteriolar anastomoses and hairpin loop formation in precapillary arterioles, sparse collecting venules in the choroid and marked capillary changes such as caliber irregularity, narrowing, tortuosity, loop formation and decreased capillaries, outpouching and microaneurysms. In the cilazapril-treated OLETF rats, these changes were markedly decreased to the level seen in the LETO rats, in which the retinal and choroidal blood vessels had a definite and fairly constant pattern and the capillaries were more regularly and densely arranged and had a remarkably uniform caliber. Our results show that the long-term administration of cilazapril before or from the initial onset significantly prevented the increase in blood sugar and inhibited the increases in serum cholesterol in OLETF rats throughout the treatment, lowered systolic arterial pressure to a nearly normal level and prevented diabetic ocular complications. The effects of cilazapril on the diabetic retinal and choroidal vasculature are described for the first time. SEM of corrosion casts is a valuable and easy technique for showing precisely and three-dimensionally the effects of some drugs on the vasculature.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2006

Measurement of choroidal melanoma basal diameter by wide-angle digital fundus camera: a comparison with ultrasound measurement.

PURPOSE: To compare the measurement of the basal diameter of choroidal melanoma, an important parameter for planning treatment and as a prognostic factor, by standardized ophthalmic ultrasound versus that obtained using a wide-angle fundus camera. METHODS: The longest and shortest basal diameters of 104 consecutive choroidal melanomas of patients seen at the ocular oncology service of the Hadassah University Hospital were measured by B-scan ultrasound and compared with those measured by a wide-angle fundus camera (Panoret-1000). Each diameter was measured thrice by two ophthalmic photographers, and intra-observer and interobserver reproducibility were calculated as well. RESULTS: The measurements of both the long and short diameters of the choroidal melanomas were significantly larger when measured by Panoret-1000 as compared with the B-scan ultrasound. There was no significant difference among the three measurements of each of the photographers. The interobserver reproducibility between the two photographers was high. CONCLUSIONS: Our findings can be attributed to the larger extent of the pigmentation of the melanoma compared to its recognized elevation. Since pigmentation of choroidal melanoma is easier to recognize than its elevation, we assume that measurement by a wide-angle fundus camera is more accurate in pigmented tumors, and should be adopted for measuring the basal diameter of choroidal melanomas in planning treatment and follow-up.

Choroid Neoplasms↗
PubMed1992

Characterization of prolactin receptors in human choroid plexus.

The specific binding of 125I-human prolactin (hPRL) was studied in different areas of the human brain. Particularly high binding affinity of the hormone was found in the choroid plexus and this tissue was therefore selected for further studies. The hippocampus, the hypothalamus and the pituitary were among other regions containing prolactin-binding sites. In the choroid plexus the amount of PRL receptors was significantly higher in females than in males and was also found in both sexes to decrease with age. The binding affinity of 125I-hPRL to choroid plexus was 3.0 x 10(9) M-1 and the binding capacity was 10.3 pmol per mg protein. Following solubilization with Triton X-100 the PRL receptor fraction retained its hormone-binding properties and upon molecular sieve chromatography it behaved as a protein with a molecular mass of approximately 250,000. Cross-linking of 125I-hPRL to receptors from choroid plexus and subsequent sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis indicated a major hormone-binding unit of M(r) 44,000. This value is about 7,000 smaller than that reported earlier by us for the growth hormone receptors from the same tissue, following cross-linking to 125I-human growth hormone (hGH). By affinity column chromatography a complete separation of the hPRL and hGH binding units was achieved. It was thus shown that in choroid plexus the binding sites for GH and PRL occur as discrete entities.

Aging↗
PubMed1988

Effects of epinephrine on retinal and choroidal blood flow through different routes of drug administration.

Epinephrine (1, 3 and 10 micrograms/kg) was found to increase retinal and choroidal blood flow (22, 49 and 67%) when it was administered intravenously. The increase in retinal and choroidal blood flow coincided well with the increase in systemic blood pressure (44, 65 and 96%, respectively). When epinephrine (2%) was instilled to the eyes topically the retinal and choroidal blood flow decreased (15%) while systemic blood pressure remained unchanged. It is suggested that the decrease in retinal and choroidal blood flow by topical epinephrine could be the cause of epinephrine maculopathy reported previously. L-Timolol (0.25%, topically) did not affect retinal and choroidal blood flow significantly.

Administration, Topical↗
PubMed1996

Sympathetic innervation of the rat choroid: an autoradiographic tracing and immunohistochemical study.

The sympathetic innervation of the choroid was investigated by means of the anterograde tracer 3H-leucine, injected into the rostral part of the superior cervical ganglion. The tracer was autoradiographically visualized at the light- and electron-microscopic levels. Labelled unmyelinated fibres were found in the choroid and labelled terminals were observed in close proximity to the smooth muscle cells of arterioles. The labelled terminals contain granular vesicles of different size and clear vesicles; the mitochondria were of the electron-dense type and no cell-to-cell synaptic contacts were observed. In addition, tyrosine hydroxylase immunocytochemistry was performed. Immunostained terminals found in the choroid show ultrastructural features similar to those found in the tracing experiments: granular vesicles of different size, clear vesicles and electron-dense mitochondria. On the basis of previous studies and the present observations, it is concluded that the choroid has a dual innervation, a parasympathetic innervation from the pterygopalatine ganglion and a sympathetic innervation from the superior cervical ganglion. The dual innervation is most likely involved in maintaining the homeostasis of vasodilatation and vasoconstriction in the choroid.

Animals↗
PubMed1985

Indocyanine green angiography of choroidal neovascular membranes.

The choroidal circulation was studied in 27 eyes with choroidal neovascular diseases by means of fluorescein and indocyanine green (ICG) angiography. In 10 of the cases the disciform response was seen to be associated with either watershed zones of the choroidal circulation or with areas of choroidal circulatory disturbance. This is consistent with the theory that hypoxic regions of the choroid are the underlying cause of macular disciform response.

Adult↗
PubMed2004

Effects of positive and negative lens treatment on retinal and choroidal glucagon and glucagon receptor mRNA levels in the chicken.

PURPOSE: It has been found in the chicken that the amount of retinal glucagon mRNA increases during treatment with positive lenses. Pharmacological studies support the idea that glucagon may act as a stop signal for visually induced eye growth. To gain more insight into the functional role of glucagon, the changes of glucagon and glucagon receptor mRNA concentrations in retina and choroid over time were studied. Furthermore, the abundance of glucagon and the glucagon receptor was studied in different fundal layers (retina, retinal pigment epithelium[RPE], choroid) and the blood. METHODS: Semiquantitative real-time RT-PCR was used to measure glucagon and glucagon receptor mRNA levels in retina and choroid after positive and negative lens treatment for 2, 6, or 24 hours, by unilateral -7- or +7-D lenses. Contralateral eyes served as the control, and completely untreated animals provided further reference data. Intravitreal colchicine injections (which are known to reduce the number of glucagon cells sharply) were used to verify that the related decline in glucagon mRNA could be measured by real-time RT-PCR. RESULTS: In the retina, treatment with -7-D lenses induced an initial upregulation of glucagon mRNA in both eyes, followed by a significant downregulation. The treatment with +7-D lenses showed a significant but transient downregulation in the control eye superimposed on a trend toward upregulation in the treated eye. However, the changes in glucagon mRNA expression were not confined to the lens-treated eyes but were also found, although sometimes to a lesser extent, in the non-lens-covered fellow eyes. There was evidence of a transient increase in glucagon receptor mRNA levels in lens-treated eyes after either -7- or +7-D lens wear. In the choroid, no effect of imposed defocus was detected. The injection of colchicine led to the destruction of approximately 75% of the glucagon amacrine cells but the mRNA level of retinal glucagon decreased by only approximately 50%. Glucagon receptor expression was found to be higher in the RPE than the retina and choroid whereas, in the blood, glucagon and glucagon receptor mRNA expression was below detection level. CONCLUSIONS: The observed bidirectional regulation of glucagon mRNA in correlation with the sign of imposed defocus supports the idea that glucagon may act as a stop-and-go signal for eye growth. This is in line with a previous proposal based on studies of changes of the glucagon peptide content.

Animals↗
PubMed2004

Intravenously administered histamine increases choroidal but not retinal blood flow.

PURPOSE: To determine the effect of intravenously administered histamine on both retinal and choroidal blood flow in humans. METHODS: A randomized, double-masked, two-way crossover study was performed in 14 healthy volunteers. Placebo or histamine was administered intravenously in stepwise increasing doses (0.08 microg/kg/min, 0.16 microg/kg/min, and 0.32 microg/kg/min). Retinal vessel diameters were measured with a retinal vessel analyzer, and retinal venous blood speed was assessed by bi-directional laser Doppler velocimetry. Using these parameters retinal blood flow was calculated. Subfoveal and pulsatile choroidal blood flow were measured with laser Doppler flowmetry and laser interferometry, respectively. RESULTS: After infusion of histamine pulsatile choroidal blood flow increased by 5 +/- 3%, 9 +/- 8%, and 14 +/- 7% (P = 0.001, ANOVA) and subfoveolar choroidal blood flow by 8 +/- 11%, 13 +/- 11%, and 13 +/- 12% (P = 0.003, ANOVA). Retinal arterial and venous vessel diameter significantly increased by 3 +/- 4%, 2 +/- 4%, and 3 +/- 5% (P = 0.047, ANOVA) and 1 +/- 2%, 3 +/- 2%, and 3 +/- 2% (P = 0.015, ANOVA), respectively. Red blood cell velocity in major retinal veins tended to decrease by -9 +/- 12%, -9 +/- 20%, and -13 +/- 12%, but this effect did not reach levels of significance. Calculated retinal blood flow was not changed by administration of histamine (-7 +/- 14%, -4 +/- 20%, and -8 +/- 12%, P = 0.28, ANOVA). CONCLUSIONS: Intravenous histamine in the selected doses increased choroidal blood flow. Retinal vessels showed a small diameter increase, whereas red blood cell speed decreased, resulting in an unchanged total retinal blood flow. This may result from local differences in the receptor distribution in the posterior part of the eye.

Adult↗
PubMed1995

Prenatal sonographic detection of isolated fetal choroid plexus cysts: should we screen for trisomy 18?

It has been established that the finding of a fetal choroid plexus cyst confers an increased risk of aneuploidy, predominantly trisomy 18. In view of this association many investigators have advocated amniocentesis when a choroid plexus cyst is identified by prenatal ultrasonography. A risk/benefit and economic analysis of such a policy is presented. When the following factors are taken into account-published data on the frequency of isolated choroid plexus cysts in second trimester fetuses, the risk of trisomy 18 in these fetuses, the population frequency of trisomy 18, the natural history and prognosis for these infants, and the risks and cost of amniocentesis--it is concluded that performing amniocentesis on second trimester fetuses with choroid plexus cysts is neither cost effective nor beneficial. For the detection of one infant with trisomy 18 that will survive past five months, 25 normal fetuses would be lost owing to amniocentesis. Identification of trisomy 18 by determining the presence of choroid plexus cysts in fetuses is not a worthwhile screening policy.

Aneuploidy↗
PubMed2005

The choroid plexus removes beta-amyloid from brain cerebrospinal fluid.

beta-Amyloid (Abeta) concentration in the cerebrospinal fluid (CSF) of the brain may be regulated by the choroid plexus, which forms a barrier between blood and brain CSF. Abeta uptake from CSF was determined as its volume of distribution (V(D)) into isolated rat choroid plexus tissue. The V(D) of [125I]Abeta1-40 was corrected by subtraction of the V(D) of [14C]sucrose, a marker for extracellular space and diffusion. Abeta uptake into choroid plexus was time and temperature dependent. Uptake of [125I]Abeta was saturable. Abeta uptake was not affected by addition of transthyretin or apolipoprotein E3. In studies with primary culture monolayers of choroidal epithelial cells in Transwells, Abeta permeability across cells, corrected by [(14)C]sucrose, was greater from the CSF-facing membrane than from the blood-facing membrane. Similarly, cellular accumulation of [125I]Abeta was concentrative from both directions and was greater from the CSF-facing membrane, suggesting a bias for efflux. Overall, these results suggest the choroid plexus selectively cleanses Abeta from the CSF by an undetermined mechanism(s), potentially reducing Abeta from normal brains and the brains of Alzheimer's disease patients.

Amyloid beta-Peptides↗