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PubMed2004

Outer retinal degeneration: an electronic retinal prosthesis as a treatment strategy.

OBJECTIVE: To review progress toward an electronic retinal prosthesis for outer retinal degeneration. METHOD: Literature review. RESULTS: Retinal degenerations such as retinitis pigmentosa result in a loss of photoreceptors. There is a secondary loss of inner retinal cells, but significant numbers of bipolar and ganglion cells remain for many years. Electrical stimulation can produce phosphenes in the eyes of individuals who are blind as a result of retinitis pigmentosa. Several research groups are trying to exploit this phenomenon to produce artificial vision with electronic retinal prostheses. Two groups, with private company sponsorship, have recently implanted first-generation devices in subjects with advanced retinitis pigmentosa. They have reported limited preliminary results. This article seeks to put these results in a broader context and review potential obstacles to successful prosthesis development. These include inner retinal cell viability, high thresholds, signal encoding, power requirements, biocompatibility, and device encapsulation. CONCLUSION: There has been substantial progress toward an electronic retinal prosthesis, but fully functional, long-lasting devices are not on the immediate horizon.

Biocompatible Materials↗
PubMed1992

Diurnal variations in the electroretinographic c-wave and retinal melatonin content in rats with inherited retinal dystrophy.

The inability of retinal pigment epithelium to phagocytose shed photoreceptor disks is a cause of retinal degeneration in the Royal College of Surgeons rat; retinal pigment epithelial phagocytosis and disk shedding are regulated by the diurnal rhythm of retinal melatonin level. The diurnal rhythms of the electroretinogram (particularly that of the retinal pigment epithelial potential, the electroretinographic c-wave) and retinal melatonin content were thus investigated in Royal College of Surgeons rats from postnatal day 17 to 24, the period preceding retinal degeneration. The amplitudes of both the b- and c-waves of the electroretinogram fell significantly during the peak time of rod disk shedding and rose after the time of expected light off in the control and dystrophic rats. While the b-wave rhythms did not differ between the two strains, diurnal changes in the c-wave were significantly less distinct in the dystrophic rats than in controls. This difference may reflect lack of phagocytosis in dystrophic rats. Furthermore, the ERG c-wave was significantly larger and prolonged, and the retinal melatonin content higher, in dystrophic rats of this age group than in controls. It appears that retinal melatonin metabolism may play an important role in the maintenance of retinal pigment epithelial and photoreceptor function.

Animals↗
PubMed2005

Incidence of cytomegalovirus (CMV) retinitis in second eyes of patients with the acquired immune deficiency syndrome and unilateral CMV retinitis.

PURPOSE: To evaluate the risk and risk factors for developing cytomegalovirus (CMV) retinitis in previously uninvolved second eyes among patients with unilateral CMV retinitis. DESIGN: Cohort study. METHODS SETTINGS: Single-center academic AIDS ophthalmology practice. PATIENT POPULATION: Three hundred seventy-six consecutive patients with AIDS and unilateral CMV retinitis were followed from the time of CMV retinitis diagnosis for the development of second-eye retinitis. EXPERIMENTAL PROCEDURES: Demographic and clinical characteristics were noted at baseline. Use of highly active antiretroviral therapy (HAART) and immune recovery in response to HAART were noted prospectively. MAIN OUTCOME MEASURE: Development of CMV retinitis in a previously uninvolved eye. RESULTS: Ninety-one percent of subjects received systemic anti-CMV treatment. Second-eye retinitis occurred in 26.1%/person-year (19.6% within the first 6 months), less than half the rate previously reported in untreated groups. Initial CD4+ T cell count >12 cells/microl, use of HAART, and initial posterior pole involvement were associated with 64%, 46%, and 41% reductions in incidence vis-à-vis comparison groups. Benefit from HAART was limited to that subset who developed immune recovery of a degree expected to restore innate control of CMV (a rise in the CD4+ T cell count by >50 cells/microl to a level >100 cells/microl). CONCLUSIONS: The risk of second-eye retinitis is substantial in patients with unilateral CMV retinitis but appears to be reduced by anti-CMV therapy and by HAART-induced immune recovery. Patients are at highest risk when CD4+ T cell counts are very low and in the months immediately after CMV retinitis diagnosis.

AIDS-Related Opportunistic Infections↗
PubMed2001

Perimetric sensitivity and retinal thickness in eyes with macular edema resulting from branch retinal vein occlusion.

PURPOSE: To document and study the relationship between perimetric sensitivity and retinal thickness at the foveal and parafoveal points in eyes with macular edema associated with branch retinal vein occlusion. METHODS: A prospective study was performed using the central 10-2 Humphrey perimetry program and optical coherence tomography. Seventeen eyes with branch retinal vein occlusion were eligible showing macular edema without macular nonperfusion or massive retinal hemorrhage. RESULTS: The sensitivity and retinal thickness were significantly correlated at the fovea (r = -0.629, P =.006) as well as 1 (r = -0.656, P <.0001) and 3 (r = -0.885, P <.0001) degrees apart from the fovea. The visual acuity that is expressed as a logarithm of the minimum angle of resolution (LogMAR) also correlated with retinal thickness (r = 0.591, P =.011). CONCLUSION: The increased retinal thickness resulting from macular edema is closely correlated with retinal sensitivity as measured by automated static perimetry both at the fovea and parafovea. Measuring the retinal thickness using optical coherence tomography may be useful in monitoring macular edema in eyes with branch retinal vein occlusion.

Adult↗
PubMed2002

Kinetic analysis of mouse retinal dehydrogenase type-2 (RALDH2) for retinal substrates.

Retinal dehydrogenase (RALDH) isozymes catalyze the terminal oxidation of retinol into retinoic acid (RA) that is essential for embryogenesis and tissue differentiation. To understand the role of mouse type 2 RALDH in synthesizing the ligands (all-trans and 9-cis RA) needed to bind and activate nuclear RA receptors, we determined the detailed kinetic properties of RALDH2 for various retinal substrates. Purified recombinant RALDH2 showed a pH optimum of 9.0 for all-trans retinal oxidation. The activity of the enzyme was lower at 37 degrees C compared to 25 degrees C. The efficiency of conversion of all-trans retinal to RA was 2- and 5-fold higher than 13-cis and 9-cis retinal, respectively. The K(m) for all-trans and 13-cis retinal were similar (0.66 and 0.62 microM, respectively). However, the K(m) of RALDH2 for 9-cis retinal substrate (2.25 microM) was 3-fold higher compared to all-trans and 13-cis retinal substrates. Among several reagents tested for their ability to either inhibit or activate RALDH2, citral and para-hydroxymercuribenzoic acid (p-HMB) inhibited and MgCl(2) activated the reaction. Comparison of the kinetic properties of RALDH2 for retinal substrates and its activity towards various reagents with those of previously reported rat kidney RALDH1 and human liver aldehyde dehydrogenase-1 showed distinct differences. Since RALDH2 has low K(m) and high catalytic efficiency for all-trans retinal, it may likely be involved in the production of all-trans RA in vivo.

Aldehyde Oxidoreductases↗
PubMedDate not supplied

Development of dendritic trees of rabbit retinal alpha ganglion cells: relation to differential retinal growth.

To provide a quantitative description of the postnatal development of dendritic trees in alpha ganglion cells of the rabbit retina, these cells were stained either by intracellular injection of Lucifer yellow or by application of the lipophilic dye DiI. This was done at three developmental stages: postnatal day (P) 8/9, P 16/17, and in adults. For different retinal locations we quantified the alpha cell dendritic field area, the number of dendritic branch points, and the average dendritic length between branch points. According to the alpha cell location, the data were collected in three groups representing the retinal center, midperiphery, and far periphery, respectively. The data were then correlated with the postnatal retinal expansion which is known to differ among the above topographic regions of the retinae (Reichenbach et al., 1993). Our results show that the growth of alpha ganglion cell dendrites is not proportional to, but significantly exceeds, that of the local retinal tissue. Between P 8/9 and adulthood, the area of central alpha cells increases almost six-fold from 26,000 to 144,000 microns 2 (retinal expansion: 2.2-fold), and that of peripheral cells more than 15-fold from 35,000 to 556,000 microns 2 (retinal expansion: four-fold). During this period, the coverage factor of alpha cell dendritic fields increases about three-fold, and reaches adult levels of about 3 (retinal center) and 2.2 (periphery), respectively. The number of dendritic branch points remains nearly constant, and the distance between them increases by a factor close to the square root of the factor by which the dendritic field area grows. Thus, it appears that, from the second postnatal week on, dendritic trees of rabbit alpha ganglion cells increase by intense "interstitial growth," rather than by outgrowth of (new) dendritic branches. This growth pattern is different from that of some other rabbit retinal ganglion cell types, and of alpha ganglion cells of the cat retina, whose dendritic trees expand at a rate equal to or less than that of the surrounding retinal tissue. The consequences for synaptic contacts with bipolar and amacrine cells are discussed; they suggest a high degree of synaptic plasticity during normal postnatal retinal growth.

Animals↗
PubMed1994

Rat liver cytosolic retinal dehydrogenase: comparison of 13-cis-, 9-cis-, and all-trans-retinal as substrates and effects of cellular retinoid-binding proteins and retinoic acid on activity.

A basic pI retinal dehydrogenase has been purified recently that accounts for approximately 90% of the all-trans-retinal dehydrogenase activity of rat liver cytosol. In this work, we show that this enzyme also accounts for approximately 90% of the 9-cis-retinal dehydrogenase activity of rat liver cytosol. The partially-purified enzyme displayed allosteric kinetics for 9-cis-retinal [K0.5 = 5.2 microM, Hill coefficient = 1.4, Vmax = 7.85 nmol min-1 (mg of protein)-1] with the ratio Vmax/K0.5 = 1.5. The latter is similar to that of 2.1 for all-trans-retinal [K0.5 = 1.6 microM, Hill coefficient = 1.4, Vmax = 3.4 nmol min-1 (mg of protein)-1]. Competition between all-trans- and 9-cis-retinal occurred only when micromolar concentrations of both were present, indicating that the dehydrogenase could catalyze both all-trans- and 9-cis-retinoic acid syntheses simultaneously at the nanomolar amounts of the retinals that are likely to occur physiologically. Although reactions of all-trans- and 9-cis-retinoids were catalyzed with similar efficiencies, 13-cis-retinal was not an efficient substrate. This retinal dehydrogenase was not feedback-inhibited by all-trans- or 9-cis-retinoic acid, nor by holocellular retinoic acid-binding protein, but was stimulated modestly by apocellular retinoic acid-binding protein, an effect not observed in the presence of cellular retinol-binding protein. These data indicate that products, via feedback inhibition, do not regulate retinoic acid synthesis by this dehydrogenase. This dehydrogenase may serve as a common enzyme in the conversion of all-trans- and 9-cis-retinal into their acids.

Aldehyde Oxidoreductases↗
PubMed2002

HIV and cytomegalovirus viral load and clinical outcomes in AIDS and cytomegalovirus retinitis patients: Monoclonal Antibody Cytomegalovirus Retinitis Trial.

OBJECTIVE: To determine the association of cytomegalovirus (CMV) viremia with mortality and CMV retinitis progression in newly diagnosed and relapsed CMV retinitis. DESIGN: Ancillary study of a randomized, placebo-controlled, phase III clinical trial. PATIENTS: A total of 83 patients with AIDS and CMV retinitis, enrolled during the first phase of the Monoclonal Antibody Cytomegalovirus Retinitis Trial, were administered MSL-109 or placebo as adjuvant therapy for CMV retinitis. MAIN OUTCOME MEASURE(S): Mortality and CMV retinitis progression. RESULTS: Treatment with MSL-109 did not predict either progression of CMV retinitis or mortality. Detection in plasma CMV DNA at baseline predicted mortality, but CMV antigenemia did not. CMV DNA was a better predictor of mortality than a high HIV viral load. Neither CMV DNA nor antigenemia predicted the progression of CMV retinitis. Among newly diagnosed patients, there was a decline in the proportion with detectable CMV viral load and CMV antigenemia in response to anti-CMV therapy. However, there was a rebound in CMV viral load to 25% and CMV antigenemia to 54.6% at 6 months. In relapsed patients, anti-CMV therapy was not associated with a change in the percentage with detectable CMV-DNA or CMV antigenemia over time. CONCLUSION: In patients with AIDS and CMV retinitis, the detection of plasma CMV DNA was associated with a higher risk of mortality than was a high HIV viral load. Anti-CMV therapy provided a transient reduction in CMV viremia in newly diagnosed but not relapsed patients with CMV retinitis. Adjuvant therapy with MSL-109 was ineffective in clearing CMV-DNA and CMV antigen from the plasma.

AIDS-Related Opportunistic Infections↗
PubMed2004

Optical coherence tomography 3: Automatic delineation of the outer neural retinal boundary and its influence on retinal thickness measurements.

PURPOSE: To investigate the automatic delineation of the outer limits of the macular neural retina, by using the optical coherence tomography (OCT)-3 built-in software, and to determine its influence in assessing retinal thickness in the normal macula. METHODS: Retrospective analysis of the OCT3 data at a tertiary-care referral center was performed to study the automatic delineation of the outer neural retina boundary generated by the OCT built-in software. In parallel, a cross-sectional study was designed to compare retinal thickness measurements obtained at specific macular regions of nine normal eyes by the automatic measurement tool with those obtained using a manual-caliper-assisted technique. RESULTS: OCT data from 121 eyes were evaluated. Two parallel, linear highly reflective layers (HRL) were visible at the level of the outer retinal boundary in normal macular regions. Disappearance of the inner and maintenance of the outer HRL was noted in the presence of eye conditions affecting the external retinal layers. The automated software delineation for the outer retinal border was primarily guided by the presence of the inner HRL, whereas the correlation of the OCT findings with the expected clinical and angiographic features on eyes presenting specific macular conditions pointed toward a deeper retinal pigment epithelium-retina interface occurring at the level of the outer HRL. There was a statistically significant difference between the retinal thickness in specific normal macular regions obtained by the automatic measurement tool and the caliper-assisted technique in which the outer retinal border delineation was based on the outer HRL (P = 0.008, Wilcoxon signed rank test). CONCLUSIONS: Incorrect delineation of the outer neural retina boundary is occurring with the automated retinal thickness measurement tool of the OCT3 software. At specific regions of the normal macula, retinal thicknesses were significantly underestimated due to such misalignment.

Adolescent↗
PubMed2006

Ultrastructural changes after artificial retinal detachment with modified retinal adhesion.

PURPOSE: Artificial retinal detachment is increasingly used in submacular surgery. However, overcoming physiological retinal adhesiveness by subretinal fluid injection is suspected to cause cellular damage and thus to limit visual rehabilitation. This experimental study was designed to examine the ultrastructural changes induced by retinal detachment under vitrectomy conditions and to evaluate factors that reduce adhesiveness and minimize cellular damage. METHODS: Twenty-one pigmented rabbits underwent vitrectomy, and the vitreous cavity was perfused for 10 minutes with various solutions. These included variations in osmolarity (314 and 500 mOsM), Ca(2+) ion concentration (Ca(2+)-supplemented, low Ca(2+), active Ca(2+) deprivation via 1 mM EDTA), temperature (19 degrees C and 34 degrees C), and ischemia (5 minutes). Nonvitrectomized eyes served as the control. Consecutively, an artificial bleb detachment was created underneath the visual streak by injecting 1 mL of buffered saline solution subretinally. Eyes were enucleated within 3 minutes, fixed with 2% glutaraldehyde/0.1 M cacodylate buffer (pH 7.4) containing 100 mM sucrose and processed for transmission electron microscopy and scanning electron microscopy. RESULTS: If a Ca(2+)-containing standard solution was used during vitrectomy, retinal adhesiveness was strong, and a forced bleb detachment caused substantial cellular damage characterized by swollen and fragmented photoreceptor outer segments and disruption of retinal pigment epithelial cells. Use of a Ca(2+)-free solution moderately reduced the adhesive strength with consequently less ultrastructural damage. Active Ca(2+)-deprivation further reduced the retinal adhesion, but may have induced damage as suggested by intracellular vacuolization. Hyperosmolarity and ischemic conditions had toxic effects on both the photoreceptors and RPE cells. In contrast, the use of a preheated Ca(2+)-free solution (34 degrees C) substantially reduced retinal adhesiveness under vitrectomy conditions and hence ultrastructural damage. CONCLUSIONS: Artificial retinal detachment causes substantial ultrastructural damage in eyes with physiological retinal adhesiveness if performed under vitrectomy conditions similar to surgery in humans. The use of a preheated Ca(2+)-free physiologic saline solution seems to be suitable to reduce retinal adhesion sufficiently, without causing significant cellular damage.

Adhesiveness↗
PubMedDate not supplied

A quantitative in vivo study of retinal thickness before and after laser treatment for macular edema due to retinal vein occlusion.

PURPOSE: To evaluate quantitatively the effect of grid laser photocoagulation in macular edema due to central and branch retinal vein occlusion, using the retinal thickness analyzer. METHODS: Five patients with cystoid and non-cystoid macular edema were studied before and after argon grid laser treatment. All were examined clinically, with fluorescein angiography, and measurement of retinal thickness. Macular thickness was correlated to visual acuity measured on the ETDRS chart. RESULTS: Laser-slit images obtained with the retinal thickness analyzer in patients with macular edema disclosed discrete intraretinal changes after photocoagulation. Biomicroscopy and fluorescein angiography were insensitive to these small changes in the retinal thickness. No patient had any change in visual acuity after three months, but the retinal thickness was greater at this interval. The retinal thickening may be explained by a postoperative inflammatory response or by altered retinal blood flow or, in two of the eyes, by the effect of combined peripheral photocoagulation. CONCLUSIONS: The retinal thickness analyzer offers a refined tool for the diagnosis of subclinical changes of macular edema in retinal vein occlusion and is therefore also useful for assessing the effects of treatment.

Aged↗
PubMed2001

Comparison of retinal transit times and retinal blood flow: a study in monkeys.

PURPOSE: To determine the correlation between transit times of retinal blood flow calculated from fluorescein angiograms and retinal blood flow determined by the microsphere method. METHODS: Two fluorescein angiograms were obtained in each eye of six monkeys, followed by determination of retinal blood flow with labeled microspheres. Angiograms in 10 eyes were analyzed for mean transit time (MTT) and arteriovenous passage time (AVP). MTT was determined in two ways: from dye curves reconstructed by extrapolation of semilogarithmic plots of the recorded curves (MTT(slope)) and by a new technique based on an impulse-response analysis (MTT(ir)). RESULTS: Mean values (+/-SD) for retinal blood flow in 10 eyes were 23.2 +/- 6.9 mg/min. Corresponding values for MTT(ir), MTT(slope), and AVP were 2.22 +/- 0.38, 4.89 +/- 5.89, and 1.08 +/- 0.14 seconds. There was a weak, but not statistically significant, correlation between retinal blood flow and MTT(ir) (r = -0.60, P = 0.06) but no useful correlation between retinal blood flow and either MTT(slope) or AVP. CONCLUSIONS: The relationship between retinal blood flow and transit times determined from fluorescein angiograms is weak. Of the three transit parameters tested, MTT(ir), determined with the recently developed impulse-response technique, had the best correlation with retinal blood flow. Further studies are needed to determine the ability of these transit parameters to detect a change in retinal blood flow and the possibility that transit times may provide useful clinical information unrelated to absolute values of retinal blood flow.

Animals↗
PubMed2002

Retinal cAMP levels during the progression of retinal degeneration in rhodopsin P23H and S334ter transgenic rats.

PURPOSE: To test whether high levels of cAMP promote apoptosis and shorten the life of retinal rod photoreceptors, the changes in cAMP levels during retinal degeneration were analyzed in two transgenic rat models that express rhodopsin P23H and S334ter mutations. METHODS: Dark- and light-adapted heterozygous P23H (lines 1 and 3; P23H-1 and -3), S334ter line 4 (S334ter-4), and Sprague-Dawley (control) rats were studied at 4 to 8 weeks by cAMP enzyme competitive immunoassay and by cAMP immunocytochemistry. RESULTS: In control animals retinal cAMP content reached a steady state level at 30 days of age. Dark-adapted control retinas had up to 97% higher cAMP content than light-adapted retinas, and photoreceptor cells were the major source of this increase. Dark-adapted photoreceptors in all three lines of transgenic rats at advanced stages of retinal degeneration had cAMP content different from that of the control. In rats that express mutant rhodopsin, the number of photoreceptor cells was progressively reduced, because of retinal degeneration, but dark-adapted cAMP levels did not decline accordingly. P23H transgenic animals of both lines had higher levels of cAMP per photoreceptor cell count than control animals. This elevation was more pronounced as degeneration progressed. S334ter animals showed smaller cAMP elevation than P23H rats at a similar stage of retinal degeneration, but at a point when S334ter rats were undergoing rapid retinal degeneration, whereas in P23H rats retinal degeneration was slowing down. CONCLUSIONS: All three lines of transgenic rats carrying rhodopsin mutations show an increase in dark-adapted photoreceptor cAMP levels. A complex relationship exists between cAMP levels and the rate of cell death in the retina. Although initially higher levels of cAMP may promote cell survival and slow down retinal degeneration, ultimately, elevated cAMP levels may become toxic and may contribute to retinal cell death.

Animals↗
PubMed1987

Functional recovery of retinal pigment epithelial damage in experimental retinal detachment.

The integrity of the RPE barrier function in retinal detachment was studied in vitro. The retinal pigment epithelium (RPE)-choroid tissue was isolated from cynomolgus monkey eyes with acute (less than 1 hr), subacute (1-2 weeks), and chronic (8-20 months) retinal detachments, and clamped between Ussing-type chambers. Electrical characteristics and choroid-to-retina permeability to carboxyfluorescein were determined. In the HEPES-buffered bathing solution, transepithelial potential difference and resistance in eyes with acute retinal detachments (0.2 mV and 134 ohm-cm2, respectively) were significantly lower than subacute (7.9 and 350) and chronic (10.4 and 348) retinal detachments. Furthermore, the permeability was increased five-fold in acute retinal detachments with respect to subacute and chronic retinal detachments, indicating a breakdown of the RPE barrier in acute retinal detachment. No statistical difference was found between subacute and chronic retinal detachments. In this animal model, RPE barrier function is destroyed at the onset of retinal detachment, but recovers in a week or two, and is maintained in the chronic stage. Histological examination revealed that RPE recovery was accomplished by RPE proliferation and hyperplasia.

Animals↗
PubMed1993

Phagocytic and digestive activities of retinal pigment epithelium at experimentally produced retinal tears.

The present study examined the phagocytic and digestive activities of retinal pigment epithelial cells (RPE cells) at sites of experimentally produced retinal tears, using the phagocytosis of the latex particles by these cells as a measure of phagocytic activity, and their acid phosphatase activity as a measure of their digestive activity. Four days after retinal tear formation, acid phosphatase activity of RPE cells at the site of retinal tears was the same as that of the RPE cells in the surrounding normal retina. However, at one week, four weeks and six months after tear formation, acid phosphatase activity of RPE cells at the site of retinal tears was higher than that of the RPE cells in the surrounding normal retina. Four weeks after retinal tear formation, a latex particle solution was injected onto the retinal tear or subretinally. The RPE cells at the site of retinal tears phagocytized the latex particles earlier than did the RPE cells of the eye which was injected subretinally. At three hours after the injection, the RPE cells at the site of retinal tear had phagocytized more latex particles in their cytoplasm than RPE cells in normal retina. It can be concluded that RPE cells at the site of retinal tear had higher phagocytic and digestive activity than did RPE cells in normal retina.

Acid Phosphatase↗
PubMedDate not supplied

Case report: indocyanine green dye leakage from retinal artery in branch retinal vein occlusion.

BACKGROUND: Little is known about retinal vascular lesions underlying hemorrhage in the acute phase of branch retinal vein occlusion (BRVO). CASE: A 64-year-old woman presented with a decrease in visual acuity of ten-day duration in her left eye. OBSERVATIONS: At the initial examination, her left fundus showed the typical appearance of BRVO, including retinal bleeding and soft exudates in the lower half of the fundus, after the arteriovenous crossing. Fluorescein angiography showed no detail in the retinal vessels, which were occluded by retinal bleeding. However, in the early phase of indocyanine green (ICG) angiography, ICG dye leaked from the retinal artery at a point proximal to the first bifurcation. In the late phase of ICG angiography, the dye pooled along the retinal artery in a fusiform fashion. One year after laser photocoagulation was performed in the area of the BRVO, ICG dye leakage from the retinal artery had completely disappeared. CONCLUSIONS: These findings suggest that the changes in the retina detected by ICG angiography may have been associated with the onset of BRVO. In patients with acute BRVO, ICG angiography may be used to evaluate retinal arterial lesions covered by hemorrhage and provide useful information.

Capillary Permeability↗
PubMed1994

Acquired peripheral retinal telangiectasia after retinal surgery.

BACKGROUND: Acquired peripheral retinal telangiectasia (APRT) is a well-recognized clinical entity that can be mistaken for conditions such as choroidal melanoma or the angiomata of von Hippel-Lindau disease. Although most cases are idiopathic, some have been shown to be associated with conditions such as uveitis and retinal detachment. METHODS: The clinical histories of four patients in whom APRT developed after retinal surgery are presented. RESULTS: For each patient studied, no retinal vascular abnormality was observed at the time of initial surgery. All patients were myopic, and three had clinical features compatible with Sticklers syndrome. APRT developed either in untreated retina remote from the area of detachment, in undetached retina treated with cryotherapy, in reattached retina in the region of subretinal fluid release, or in reattached retina over a scleral buckle. CONCLUSIONS: Possible risk factors for the development of APRT include retinal ischemia after longstanding retinal detachment, retinal cryotherapy or scleral buckling, and damage to Bruch's membrane at the time of scleral suture placement or release of subretinal fluid. This report provides further evidence of an association between APRT and retinal detachment, and that APRT may be more specifically associated with retinal detachments in patients with Sticklers syndrome.

Adult↗
PubMed2003

Establishment of conditionally immortalized rat retinal pericyte cell lines (TR-rPCT) and their application in a co-culture system using retinal capillary endothelial cell line (TR-iBRB2).

The purpose of this study was to establish and characterize a retinal pericyte cell line from retinal capillaries of transgenic rats harboring the temperature-sensitive simian virus 40 large T-antigen gene (tsA58 Tg rat), and to apply this to the co-culture with a retinal capillary endothelial cell line. The conditionally immortalized rat retinal pericyte cell lines (TR-rPCTs), which express a temperature-sensitive large T-antigen, were obtained from two tsA58 Tg rats. These cell lines had a multicellular nodule morphology and reacted positively with von Kossa staining, a marker of calcification. TR-rPCTs cells expressed mRNA of pericyte markers such as rat intercellular adhesion molecule-1, platelet-derived growth factor-receptor beta, angiopoietin-1, and osteopontin. Western blot analysis indicated that alpha-smooth muscle actin (alpha-SMA) was expressed in TR-rPCT3 and 4 cells. In contrast, alpha-SMA was induced by transforming growth factor-beta1 and its enhancement was reduced by basic fibroblast growth factor in TR-rPCT1 and 2 cells. When TR-rPCT1 cells were cultured with a rat retinal endothelial cell line (TR-iBRB2) in a contact co-culture system, the number of TR-iBRB2 cells were significantly reduced in comparison with that of a single culture of TR-iBRB2 cells, suggesting that physical contact between pericytes and retinal endothelial cells is important for the growth of retinal endothelial cells. In conclusion, conditionally immortalized retinal pericyte cell lines were established from tsA58 Tg rats. These cell lines exhibited the properties of retinal pericytes and can be applied in co-culture systems with a retinal capillary endothelial cell line.

Actins↗