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PubMed2000

Altered gravity downregulates aquaporin-1 protein expression in choroid plexus.

Aquaporin-1 (AQP1) is a water channel expressed abundantly at the apical pole of choroidal epithelial cells. The protein expression was quantified by immunocytochemistry and confocal microscopy in adult rats adapted to altered gravity. AQP1 expression was decreased by 64% at the apical pole of choroidal cells in rats dissected 5.5-8 h after a 14-day spaceflight. AQP1 was significantly overexpressed in rats readapted for 2 days to Earth's gravity after an 11-day flight (48% overshoot, when compared with the value measured in control rats). In a ground-based model that simulates some effects of weightlessness and alters choroidal structures and functions, apical AQP1 expression was reduced by 44% in choroid plexus from rats suspended head down for 14 days and by 69% in rats suspended for 28 days. Apical AQP1 was rapidly enhanced in choroid plexus of rats dissected 6 h after a 14-day suspension (57% overshoot, in comparison with control rats) and restored to the control level when rats were dissected 2 days after the end of a 14-day suspension. Decreases in the apical expression of choroidal AQP1 were also noted in rats adapted to hypergravity in the NASA 24-ft centrifuge: AQP1 expression was reduced by 47% and 85% in rats adapted for 14 days to 2 G and 3 G, respectively. AQP1 is downregulated in the apical membrane of choroidal cells in response to altered gravity and is rapidly restored after readaptation to normal gravity. This suggests that water transport, which is partly involved in the choroidal production of cerebrospinal fluid, might be decreased during spaceflight and after chronic hypergravity.

Animals↗
PubMed2000

Expression and channel properties of alpha-bungarotoxin-sensitive acetylcholine receptors on chick ciliary and choroid neurons.

Cell-specific expression of nicotinic acetylcholine receptors (AChRs) was examined using ciliary and choroid neurons isolated from chick ciliary ganglia. At embryonic days 13 and 14 (E13,14) the neurons can be distinguished by size, with ciliary neuron soma diameters exceeding those of choroid neurons by about twofold. Both neuronal populations are known to express two major AChR types: alpha3*-AChRs recognized by mAb35, that contain alpha3, alpha5, beta4, and occasionally beta2 subunits, and alpha-bungarotoxin (alphaBgt)-AChRs recognized and blocked by alphaBgt, that contain alpha7 subunits. We found that maximal whole cell current densities (I/C(m)) mediated by alphaBgt-AChRs were threefold larger for choroid compared with ciliary neurons, while alpha3*-AChR current densities were similar in the two populations. Different densities of total cell-surface alphaBgt-AChRs could not explain the distinct alphaBgt-AChR response densities associated with ciliary and choroid neurons. Ciliary ganglion neurons display abundant [(125)I]-alphaBgt binding ( approximately 10(6) sites/neuron), but digital fluorescence measurements revealed equivalent site densities on both populations. AChR channel classes having single-channel conductances of approximately 30, 40, 60, and 80 pS were present in patches excised from both ciliary and choroid neurons. Treating the neurons with alphaBgt selectively abolished the 60- and 80-pS events, identifying them as arising from alphaBgt-AChRs. Kinetic measurements revealed brief open and long closed durations for alphaBgt-AChR channel currents, predicting a very low probability of being open (p(o)) when compared with 30- or 40-pS alpha3*-AChR channels. None of the channel parameters associated with the 60- and 80-pS alphaBgt-AChRs differed detectably, however, between choroid and ciliary neurons. Instead calculations based on the combined whole cell and single-channel results indicate that choroid neurons express approximately threefold larger numbers of functional alphaBgt-AChRs (N(F)) per unit area than do ciliary neurons. Comparison with total surface [(125)I]-alphaBgt-AChR sites (N(T)), reveals that N(F)/N(T) << 1 for both neuron populations, suggesting that "silent" alphaBgt-AChRs predominate. Choroid neurons may therefore express a higher density of functional alphaBgt-AChRs by recruiting a larger fraction of receptors from the silent pool than do ciliary neurons.

Animals↗
PubMed1990

Localization and characterization of binding sites for circulating and cerebroventricular atrial natriuretic factor in rat choroid plexus.

In vitro autoradiographic studies showed that high-affinity atrial natriuretic factor (ANF) binding sites are present on rat choroid plexus (Kd = 83.8 pM, Bmax = 22.9 fmol/mg protein). Guanylate cyclase-coupled receptors (ANF-R1) represent 30% and non-guanylate cyclase-coupled ANF receptors (ANF-R2) represent 70% of the total ANF receptors present in this tissue. To provide detailed cellular localization of the binding sites, the technique of electron-microscopic autoradiography was applied using 125I-ANF (Ser 99-Tyr 126) as an in vivo ligand. In order to identify possible binding sites at the basolateral and the apical aspects of the choroid plexus, the ligand was injected into the carotid artery or into the lateral cerebral ventricles, respectively. Light-microscopic autoradiography demonstrated that ANF binds specifically to choroid plexus regardless of its route of administration. Electron-microscopic autoradiography showed that silver grains were localized primarily on epithelial cells of the choroid plexus (96-99%) and marginally on endothelial and pial cells. In choroidal epithelial cells, ultrastructural analysis of silver grain distribution revealed that, at 2 min after intracarotid or intracerebroventricular 125I-ANF injection, lysosomes were the most distinctly labeled organelle (highest relative specific radioactivity). HPLC Chromatographic analysis disclosed that 96-99% of choroid plexus-bound ANF was already degraded 2 min after injection and that at least 63-66% of the degradation took place at the plasma membrane. These results indicate that ANF binding sites are present on both aspects of choroidal epithelium, and suggest that ANF is very quickly degraded in choroid plexus by membrane-associated as well as lysosome-associated processes.

Animals↗
PubMed1997

Choroidal ganglion cell plexus and retinal vasculature in monkeys with laser-induced glaucoma.

The choroid of primates possesses an elaborate nitrergic nerve fiber plexus containing a great number of ganglion cells. Postganglionic nerve fibers innervate mainly the choroidal vasculature. In addition, the choroid contains an elastic muscular system closely associated to the vasculature. The goal of the present investigation was to analyze how sustained IOP elevation would affect the choroidal vasculature with its specialized innervation and the adjacent retina. For this purpose the posterior eye segment of 15 rhesus monkeys which after laser coagulation of the trabecular meshwork developed elevated IOP up to 4 years were studied using immunohistochemical and histochemical methods, and scanning electron microscopy of corrosion casts. The most striking finding was a significant reduction of choroidal thickness and loss of choroidal ganglion cells and nerve fibers, especially in the central portion of the choroid. Corrosion casts of the choroidal vasculature showed a slight decrease in capillary density and a decrease in length of the arterioles in glaucomatous eyes. Whole mount preparations of the retina stained for NADPH diaphorase revealed a significant reduction in positively stained amacrine cells, reduction in diameter of arterioles and changes in the staining pattern of the retinal vasculature, particularly in the perimacular region.

Animals↗
PubMed1988

Humoral regulation of blood flow to choroid plexus: role of arginine vasopressin.

The goal of this study was to examine humoral mechanisms that regulate blood flow to the choroid plexus. We determined the effects of arginine vasopressin on blood flow (microspheres) to the choroid plexus in anesthetized and awake rabbits. In anesthetized rabbits, blood flow to the choroid plexus was 342 +/- 31 (mean +/- SEM) ml/min/100 g under control conditions. Intravenous infusion of vasopressin at 4 and 40 mU/kg increased plasma vasopressin levels from 11 +/- 1 to 55 +/- 15 and 441 +/- 120 pg/ml, respectively, and blood flow to the choroid plexus decreased by 48 +/- 6% and 70 +/- 4%. Cerebral blood flow was not affected by infusion of vasopressin. Similar responses to infusion of vasopressin were observed in awake rabbits. The V1 antagonist [d(CH2)5Tyr(Me)AVP] (10 micrograms/kg i.v.) had no effect on resting blood flow, but abolished the effect of vasopressin on blood flow to the choroid plexus. Vasoconstrictor responses of the choroid plexus to intravenous infusion of phenylephrine were not attenuated by the V1 antagonist. Thus, circulating vasopressin, at plasma levels that are observed under physiological and pathophysiological conditions, has marked effects on blood flow to the choroid plexus. These effects appear to be mediated through a V1 receptor. We speculate that vasopressin may play an important role in regulation of blood flow to the choroid plexus and perhaps in the regulation of cerebrospinal fluid production.

Animals↗
PubMed2003

Role of NO in choroidal blood flow regulation during isometric exercise in healthy humans.

PURPOSE: Nitric oxide (NO) is an important regulator of basal choroidal blood flow. Animal experiments indicate that NO is also involved in choroidal blood flow regulation during changes in ocular perfusion pressure and inhibition of NO synthase (NOS) has been reported to shift choroidal pressure-flow curves to the right. The hypothesis for the study was that inhibition of NOS may influence choroidal blood flow during isometric exercise. METHODS: To test this hypothesis, a randomized, double-masked, placebo-controlled, three-way crossover study was performed in 12 healthy male volunteers. Subjects received on different study days intravenous infusions of N(G)-monomethyl-L-arginine (L-NMMA), phenylephrine, or placebo. During these infusion periods, subjects were asked to squat for 6 minutes. Choroidal blood flow was assessed with laser Doppler flowmetry, and ocular perfusion pressure (OPP) was calculated from mean arterial pressure and intraocular pressure. RESULTS: L-NMMA and phenylephrine increased resting OPP by 10% and 13%, respectively, but only L-NMMA reduced resting choroidal blood flow (-17%, P < 0.001). The relative increase in OPP during isometric exercise was comparable with all drugs administered. Isometric exercise increased choroidal blood flow during administration of placebo and phenylephrine, but not during administration of L-NMMA (P < 0.001 vs. placebo). CONCLUSIONS: These data indicate that NO plays an important role in the regulation of choroidal blood flow during isometric exercise.

Adult↗
PubMed2006

Bovine and porcine transscleral solute transport: influence of lipophilicity and the Choroid-Bruch's layer.

PURPOSE: To determine the influence of the choroid-Bruch's layer and solute lipophilicity on in vitro transscleral drug permeability in bovine and porcine eyes. METHODS: The in vitro permeability of two VEGF inhibitory drugs, budesonide and celecoxib, which are lipophilic and neutral at physiologic pH, and of three marker solutes, 3H-mannitol (hydrophilic, neutral), sodium fluorescein (hydrophilic, anionic), and rhodamine 6G (lipophilic, cationic), were determined across freshly excised scleras, with or without the underlying choroid-Bruch's layer. Select studies were performed using porcine sclera with and without choroid-Bruch's layer. Neural retina was removed by exposure of the eyecup to isotonic buffer and wherever required, the retinal pigment epithelial (RPE) layer of the preparation was disrupted and removed by exposure to hypertonic buffer. Because of the poor solubility of celecoxib and budesonide, permeability studies were conducted with 5% wt/vol of hydroxypropyl-beta-cyclodextrin (HPbetaCD). For other solutes, permeability studies were conducted, with and without HPbetaCD. Partitioning of the solutes into bovine sclera and choroid-Bruch's layer was also determined. RESULTS: The calculated log (distribution coefficient) values were -2.89, -0.68, 2.18, 3.12, and 4.02 for mannitol, sodium fluorescein, budesonide, celecoxib, and rhodamine 6G, respectively. Removal of RPE was confirmed by transmission electron microscopy and differences in the transport of mannitol. The order of the permeability coefficients (Papp) across sclera and sclera-choroid-Bruch's layers in bovine and porcine models was 3H-mannitol > fluorescein > budesonide > celecoxib > rhodamine 6G, with HPbetaCD, and 3H-mannitol > fluorescein > rhodamine 6G, without HPbetaCD. The presence of choroid-Bruch's layer reduced the bovine scleral permeability by 2-, 8-, 16-, 36-, and 50-fold and porcine tissue permeability by 2-, 7-, 15-, 33-, and 40-fold, respectively, for mannitol, sodium fluorescein, budesonide, celecoxib, and rhodamine 6G. The partition coefficients measured in bovine tissues correlated positively with the log (distribution coefficient) and exhibited a trend opposite that of transport. The partition coefficient ratio of bovine choroid-Bruch's layer to sclera was approximately 1, 1.5, 1.7, 2, and 3.5, respectively, for the solutes, as listed earlier. CONCLUSIONS: The choroid-Bruch's layer is a more significant barrier to drug transport than is sclera. It hinders the transport of lipophilic solutes, especially a cationic solute, more than hydrophilic solutes and in a more dramatic way than does sclera. The reduction in transport across this layer directly correlates with solute binding to the tissue. Understanding the permeability properties of sclera and underlying layers would be beneficial in designing better drugs for transscleral delivery.

Animals↗
PubMedDate not supplied

Choroidal detachment following retinal detachment surgery: an analysis and a new hypothesis to minimize its occurrence in high-risk cases.

PURPOSE: To determine factors predisposing to the development of choroidal detachment following conventional retinal detachment surgery, to evaluate its clinical course, and to identify possible measures to reduce its occurrence. METHODS: Analysis of 25 consecutive cases of choroidal detachment following retinal detachment surgery out of a total of 510 cases undertaken at a tertiary care referral eye center over a period of 15 months. RESULTS: The incidence of developing choroidal detachment was 4.9%. The mean age was 61 years (range 28 to 76 years) and there was no sex predilection. Hypertension was present in 16% (n=4). A total of 44% (n=11) of patients had myopia and with respect to the lens status, 44% (n=11) were phakic, 36% (n=9) were pseudophakic, and 20% (n=5) were aphakic. Redetachment of the retina was observed in 12% (n=3) of cases. Elevated intraocular pressure developed in 12% (n=3). In one patient with an anterior chamber intraocular lens and "kissing" choroidal detachment, drainage of the choroidals was undertaken to prevent corneo-lenticular touch and corneal decompensation. In two patients with redetachment, anatomic settlement of the retina was achieved only following vitreoretinal surgery. CONCLUSIONS: The following preoperative and intraoperative factors are associated with a significantly increased risk of choroidal detachment following retinal detachment: higher age, myopia, posteriorly placed explants even if its extent is less, anteriorly placed explants whenever its extent is large, drainage of subretinal fluid, and intraoperative hypotony. Choroidal detachment may also occur in patients with only a radial sponge. Designing a notch intraoperatively in the region of the explants overlying the vortex veins may help to reduce the risk of choroidal detachment following conventional retinal detachment surgery.

Adult↗
PubMedDate not supplied

Peripheral choroidal neovascularization.

Peripheral choroidal neovascularization can result in an elevated subretinal lesion which can simulate a choroidal tumor. We reviewed 8 eyes with 11 peripheral areas of subretinal fluid and exudate which were subsequently determined to be secondary to peripheral choroidal neovascularization. Previous reports of peripheral choroidal neovascularization have emphasized the hemorrhagic nature of these lesions which can simulate a choroidal melanoma. In contrast, turbid subretinal fluid and exudate characterized the majority of peripheral lesions in this series and the majority of these patients were referred with a diagnosis of choroidal metastasis. Clinical examination with fluorescein angiography and echography can effectively distinguish these areas of peripheral choroidal neovascularization from choroidal metastasis.

Aged↗
PubMed2005

Intramedullary ectopic choroid plexus: report of a rare case.

OBJECTIVE AND IMPORTANCE: Intracranial cysts containing an ectopic choroid plexus or choroid plexus-like tissue have seldom been described in the literature. However, there has been no report of a spinal intramedullary cyst containing an ectopic choroid plexus. This is the first case report in the available literature of an ectopic choroid plexus tissue in the spinal cord. CLINICAL PRESENTATION: A 30-year-old man presented with complaints of progressive descending weakness of both upper limbs and increasing stiffness of the lower limbs along with numbness of all four limbs without a history of any bowel or bladder disturbances. Examination was suggestive of a C5-T2 intramedullary lesion. Magnetic resonance imaging revealed a C6-T2 intramedullary cystic lesion along with a small anterosuperiorly placed lesion enhancing with contrast. INTERVENTION: A C6-T2 laminotomy and exploration of the intramedullary cyst and gross total microsurgical excision of the reddish vascular frond-like structure resembling the choroid plexus were performed along with a syringostomy. A laminoplasty with miniplates and screws was performed. Histopathological and immunohistochemical studies revealed a normal choroid plexus. The patient has been followed for 1 year and has demonstrated symptomatic improvement. CONCLUSION: Although there have been rare case reports of drop metastasis of choroid plexus papillomas in the spine, this is the first case report in the available literature of normal but ectopic choroid plexus tissue in the spinal cord.

Adult↗
PubMed1994

Choroid plexus-ventricular wall separation in fetuses with normal-sized cerebral ventricles at sonography: postnatal outcome.

OBJECTIVE: The choroid plexus typically fills the atrium of the lateral ventricles of the brain in normal fetuses, but separates from the medial ventricular wall with increasing ventriculomegaly. Sonographic depiction of choroid plexus-ventricular wall separation has been associated with a high frequency of unfavorable outcomes in fetuses with mild ventricular dilatation. This separation, however, is also observed in a small subgroup of fetuses with normal ventricular measurements. The objective of this study was to ascertain the prognosis for fetuses when choroid plexus-ventricular wall separation and normal-sized lateral ventricles are seen on antenatal sonograms. MATERIALS AND METHODS: Postnatal follow-up was reviewed for 74 fetuses showing a 3 mm or greater separation between the choroid plexus and the medial ventricular wall and normal-sized (< or = 10 mm) ventricles on antenatal sonograms. Fetuses were divided into normal and abnormal outcome groups, and the data were analyzed to determine if the amount of separation, the ventricular atrial diameter, or the evolution of these findings on follow-up sonograms was predictive of outcome. RESULTS: Fifty-nine patients (80%) had normal outcomes (defined as no congenital anomalies and no significant subsequent medical history apart from usual infant and childhood illnesses) and 15 patients (20%) had abnormal outcomes. The severity of the abnormalities varied widely, ranging from relatively inconsequential, such as isolated polydactyly, to complex congenital malformation syndromes resulting in neonatal death. No consistent pattern of malformation was evident. Although we found a statistically significant difference in the degree of choroid plexus-ventricular wall separation when fetuses were separated into normal and abnormal outcome groups, the range of measurements obtained in these two populations overlapped considerably. Outcomes were normal in all 13 patients in whom the choroid plexus-ventricular wall separation had returned to normal by the time of the last antenatal sonogram. CONCLUSION: A separation of 3 mm or greater between the choroid plexus and the medial ventricular wall is an important finding that is associated with an increased risk of an abnormal outcome even in the subpopulation of fetuses with normal-sized ventricles. Although the outcome will be normal in the majority (80%) of such fetuses, identification of choroid plexus-ventricular wall separation mandates a meticulous examination of fetal anatomy.

Abnormalities, Multiple↗
PubMed1992

Vasoactive intestinal polypeptide-containing nerve fibers are increased in abundance in the choroid of dystrophic RCS rats.

As photoreceptor degeneration progresses in Royal College of Surgeons (RCS) rats, a variety of morphological and physiological alterations occur in the outer retina. Since the choriocapillaris responds to changes in the outer retina in other retinopathies, we examined the possibility that changes in the choroidal vasculature also occur in RCS rats. The choroidal and choriocapillary vessels in RCS and control (RCS-rdy+) rats were examined during the period after which photoreceptor loss and retinal vascular changes had occurred (7-mos to 28-mos). Light microscopic (LM) morphometry and electron microscopic (EM) examination showed no significant differences between these groups in the number, size or morphology of these vessels. However, EM image analysis revealed that nerve fibers and bundles were twice as abundant in the RCS choroid than in the control. Using immunohistochemical techniques at the LM level combined with image analysis we found that vasoactive intestinal polypeptide positive (VIP+) fibers were significantly increased in the RCS choroid compared with control choroid. In contrast, the abundance of immunoreactive fibers labelled for substance P and dopamine beta hydroxylase appeared similar in both the control and RCS choroid. Since VIP is a potent vasodilator, the increased abundance of nerve fibers in the RCS choroid in conjunction with the unaltered number and size of these vessels suggests that choroidal blood flow may be increased. It is uncertain whether this increase is a response to the outer retinal pathology or contributes to it.

Animals↗
PubMedDate not supplied

Choroid plexus cysts.

BACKGROUND: Research shows that there is an association between choroid plexus cysts and aneuploidy. Family physicians treating prenatal patients should understand the management of this sonographic finding. OBJECTIVE: To determine the epidemiology, pathophysiology, and management of prenatal choroid plexus cysts. CASE REPORT: A 23-year-old patient, gravida 1, para 0, was seen at an inner city Family Medicine health center for prenatal care. A screening ultrasonogram performed at 16 weeks of gestation showed bilateral choroid plexus cysts approximately 5 mm in diameter. The patient declined amniocentesis. Maternal serum triple screen markers (maternal serum alpha-fetoprotein, human chorionic gonadotropin, and estriol) were all normal, as was the level II sonogram at 20 weeks and the fetal echocardiogram at 28 weeks. At birth the baby was found to be normal after a clinical assessment was performed. METHODS: A review of the literature using MEDLINE with the search strategy of choroid plexus, choroid plexus fetus/fetal, choroid plexus management, choroid plexus treatment, and choroid plexus epidemiology.

Choroid Plexus↗
PubMed1993

Colloid cyst of the third ventricle. A comparative immunohistochemical study of neuraxis cysts and choroid plexus epithelium.

In an effort to shed light upon the nature of the colloid cyst, the immunohistochemical properties of 21 examples of this lesion were compared with those of other neuraxial cysts and choroid plexus epithelium. The neuraxial cysts included the following: eight Rathke's cleft cysts, 25 pituitaries containing follicular cysts of the pars intermedia, and four enterogenous cysts. Fifteen examples of normal choroid plexus and 12 choroid plexus papillomas were studied as well. These lesions were examined for localization of the following antigens: cytokeratins, epithelial membrane antigen, secretory component, carcinoembryonic antigen, prealbumin, vimentin, glial fibrillary acidic protein (GFAP), S-100 protein, neuron-specific enolase, 68-kD neurofilament protein, chromogranin, serotonin, and lysozyme, and with Leu-7 monoclonal antibodies. Five colloid cysts were immunostained with monoclonal antibodies that were specific for Clara-cell antigens and surfactant, respectively. Sugar moieties were localized using Ulex europaeus I, and Ricinus communis agglutinin I lectins. All Rathke's cleft cysts and follicular cysts of the pars intermedia as well as three selected colloid cysts were examined for pituitary hormones. The epithelial cells of colloid and enterogenous cysts, as well as those lining follicular and Rathke's cleft cyst, showed uniformly strong reactivity for cytokeratins, epithelial membrane antigen, secretory component, and vimentin, and bound Ulex europaeus lectin. Occasional cells in colloid cysts were positive for Clara cell-specific antigens. Reaction for carcinoembryonic antigen was present on the apical surface of scattered cells of colloid, follicular, and Rathke's cleft cysts. Many cells of follicles in the pars intermedia as well as individual cells of five Rathke's cleft cysts were also immunoreactive for chromogranin, S-100 protein, GFAP, and pituitary hormones. Colloid and enterogenous cysts were negative for prealbumin, S-100 protein, GFAP, and neuron-specific enolase; in all but a few instances, they failed to bind Ricinus communis agglutinin. In contrast, normal choroid plexus and choroid plexus papillomas were positive for prealbumin, S-100 protein, neuron-specific enolase, cytokeratin, vimentin, and Ricinus communis agglutinin receptors; they lacked Ulex europaeus lectin, 56/66-kD cytokeratins, and epithelial membrane antigen. Unlike normal choroid plexus, choroid plexus papillomas were often GFAP-positive. All tissues studied were nonreactive for lysosome, serotonin, and neurofilament, and with Leu-7 antibodies. This study indicates that the immunophenotype of epithelium lining colloid cysts is similar to that of other cysts showing endodermal or ectodermal differentiation and to respiratory tract mucosa. Epithelium of colloid cysts is immunohistochemically different from that of normal or neoplastic choroid plexus. These findings indicate an endodermal rather than neuroepithelial nature for colloid cysts.

Brain Diseases↗
PubMed2006

Macular choroidal neovascularization in myopic eyes after phakic intraocular lens implantation.

PURPOSE: To analyze the development and characteristics of choroidal neovascularization in highly myopic patients corrected by the implantation of phakic intraocular lenses (PIOLs). METHODS: This retrospective, noncomparative interventional case series studied the development of choroidal neovascularization in 522 consecutive highly myopic eyes (spherical equivalent refraction >-6.00 diopters [D] and/or axial length >26 mm) (323 patients) corrected by the implantation of PIOLs, the treatment performed, and the results obtained. Parameters evaluated were best spectacle-corrected visual acuity (BSCVA) before and after treatment of choroidal neovascularization, and the interval between refractive surgery and the development of choroidal neovascularization. RESULTS: Follow-up ranged from 12 to 145 months (mean: 60.4 +/- 39.1 months). In 12 (2.29%) eyes, choroidal neovascularization developed after PIOL implantation at a mean interval time of 33.7 +/- 29.6 months (range: 1 to 87 months). Using Kaplan-Meier analysis, the risk of choroidal neovascularization in patients with high myopia corrected by PIOL implantation was 0.57% at 5 months, 0.81% at 18 months, 1.31% at 24 months, and 3.72% at 87 to 145 months. No statistically significant differences were found between patients with and without choroidal neovascularization in the following parameters: axial length (P=.826), age (P=.296), initial BSCVA (P=.085), spherical equivalent refraction (P=.663), and follow-up (P=.955). CONCLUSIONS: Phakic intraocular lens implantation for the correction of high myopia does not play a role in the development of choroidal neovascularization.

Adult↗
PubMed2026

Genome-wide discovery reveals 30 loci for choroidal thickness and uncovers potential causal links with angle-closure glaucoma.

The choroid is critical for maintaining vision and implicated in several ocular diseases, being the sole source of nutrients and waste removal for the outer retina. Genetic discovery can help elucidate the pathways through which choroidal features influence disease risk. Our meta-analysis of genome-wide association studies (n= 78,682 participants) identified 30 genomic regions, including 20 novel loci, associated with choroidal thickness. Findings suggest inflammatory and vascular processes drive choroidal thickness, with overlapping mechanisms shared with refractive error. Genome-wide independently significant SNPs accounted for 18.7% of the genetic variance in choroidal thickness. Mendelian randomisation analyses showed a causal effect of age-related macular degeneration on choroidal thickness, and suggest a bidirectional causal effect between choroidal thickness and primary angle-closure glaucoma. These findings provide insight into the shared genetic architecture and biological pathways linking choroidal thickness and related diseases.

Canadian Longitudinal Study on Aging↗
PubMed2004

Second-trimester sonography and trisomy 18: the significance of isolated choroid plexus cysts after an examination that includes the fetal hands.

OBJECTIVE: To estimate the risk of trisomy 18 with the finding of isolated choroid plexus cysts after a standard sonographic examination that is extended to include the fetal hands. METHODS: Aretrospective chart review was performed on all fetuses with choroid plexus cysts on second-trimester sonographic examinations. When choroid plexus cysts were identified, our standard protocol for fetal evaluation was expanded to include the hands. If no other findings were noted on completion of this examination, the choroid plexus cysts were classified as "isolated." These results were correlated with the presence or absence of trisomy 18 to determine the impact of this approach for the detection of fetuses with this aneuploidy. RESULTS: From March 1990 to the end of 2001, 49,435 fetuses that were subsequently delivered at our hospital were scanned between 16 and 25 menstrual weeks. At least 1 choroid plexus cyst was detected in 1209 fetuses (2.3%), of which 1060 were isolated. No fetuses with isolated choroid plexus cysts had trisomy 18. However, 3 fetuses with trisomy 18 had choroid plexus cysts and abnormal hands as their only abnormal findings. CONCLUSIONS: Fetuses with an apparently isolated finding of choroid plexus cysts can be further evaluated by extending the standard examination to include the hands. If no other findings are identified, the risk of trisomy 18 appears to be low.

Adult↗
PubMed1999

Light and choroidal PO2 modulation of intraretinal oxygen levels in an avascular retina.

PURPOSE: To determine the influence that choroidal oxygen level and outer retinal oxygen demand have on oxygen availability to the inner retina when the choroid is the only source of retinal oxygenation. This condition prevails in avascular retinas and in vascularized retinas suffering vascular occlusion. METHODS: Oxygen-sensitive microelectrodes were used to measure the oxygen tension as a function of depth in the naturally avascular retina of anesthetized and mechanically ventilated guinea pigs (n = 6). Choroidal PO2 was manipulated by varying the ventilation gas mixture, and outer retinal oxygen consumption was modulated by light-dark adaptation. Individual PO2 profiles were fitted to a multilayer mathematical model of PO2 distribution, and pairs of profiles at different choroidal PO2 levels, or under light and dark conditions, were fitted to an intraretinal PO2 difference model. Both models reflect the purely choroidal supply of retinal oxygenation. RESULTS: An increase in choroidal PO2 produced an equivalent increase in all retinal layers. Light induced a decreased oxygen consumption in the region of the inner segments of the photoreceptors, which resulted in a significant increase in PO2 in this layer, flowing on unattenuated to all inner retinal layers. The intraretinal PO2 distribution and the light- and ventilatory-induced changes in PO2 were consistent with theoretical predictions of the mathematical models. CONCLUSIONS: The present experimental studies confirm that when the choroid is the only source of retinal oxygenation, the full effect of increased choroidal oxygen level or reduced uptake in the outer retina passes through to the inner retinal layers if the oxygen utilization by the inner retina remains constant.

Animals↗