Altered expression of aquaporins 1 and 4 coincides with neurodegenerative events in retinas of spontaneously diabetic Torii rats.

Evidence is mounting that not only microangiopathy, but also neurodegenerative events occur in the retinas of humans and rodents with early diabetes. Diverse pathologies are known to alter the amount and/or location of glial expression of the water-selective channels aquaporins (AQPs) 1 and 4. However, the temporal relationships among glial activation, the altered expression of the AQP proteins and neuronal death in the retinas of diabetic animals remains to be investigated. Male spontaneously diabetic Torii (SDT) rats reportedly develop diabetes by 40 weeks of age at the latest and manifest proliferative diabetic retinopathy at 50 weeks or later. This study compared temporal changes in neuroretinal apoptosis, glial fibrillary acidic protein (GFAP) expression and the expression of AQPs 1 and 4 between SDT rat retinas and age-matched Sprague-Dawley (SD) rat retinas. Cell death was detected by terminal deoxynucleotidyl transferase-mediated deoxy-uridine triphosphate nick end-labeling on retinal flatmounts and activated caspase 3 immunofluorescence of retinal cryosections. The expression of GFAP and AQPs 1 and 4 was assessed by immunohistochemistry of cryosections and retinal flatmounts. Diabetes started to develop around 15 weeks in SDT rats. Apoptotic cells in the ganglion cell layer and the inner nuclear layer were significantly more numerous in 40-week-old SDT rat retinas than in either age-matched SD rat retinas or 10-week-old SDT rats. GFAP immunoreactivity was confined to the nerve fiber layer both in SD and SDT rats at 10 weeks, whereas it spanned the whole retina in SDT rats, but not in SD rats, at 40 weeks. AQP1 was expressed in the outer retina, whereas AQP4 was expressed in the perivascular and end feet of Müller cells and astrocytes in the inner retina in the control SD rats and the SDT rats at 10 weeks. The perivascular AQPs shifted from AQP4 to AQP1 in 40-week-old SDT rats that exhibited marked hyperglycemia. Thus, the development of diabetes increases neuroretinal apoptosis, and this coincides with an altered expression pattern of GFAP and water-selective channels AQPs 1 and 4 in SDT rats.

Intraocular pressure elevation after injection of triamcinolone acetonide: a multicenter retrospective case-control study.

PURPOSE: To determine the risk factors for intraocular pressure (IOP) elevation after the injection of triamcinolone acetonide (TA). DESIGN: Retrospective interventional case-control study. SETTING: Multicenter. PATIENT POPULATION: Four hundred and twenty-seven patients. OBSERVATION PROCEDURES: Intraocular pressure levels after TA treatment by the sub-Tenon capsule injection (STI; 12 mg, 20 mg, or 40 mg), intravitreal injection (IVI; 4 mg or 8 mg), or the combination of STI (20 mg) and IVI (4 mg), and IOP levels after two TA treatments. MAIN OUTCOME MEASURE: Risk factors for IOP levels of 24 mm Hg or higher. RESULTS: Younger age (hazards ratio [HR], 0.96/year; P < .0001), IVI (HR, 1.89/year; P < .0001), and higher baseline IOP (HR, 1.15/mm Hg; P = .003) were identified as risk factors. Dose dependency was shown in STI-treated eyes (HR, 1.07/mg; P = .0006), as well as after IVI (HR, 1.64/mg; P = .013). The combination of STI and IVI was a significant risk factor (HR, 2.27; P = .003) compared with STI alone. In eyes receiving two TA treatments, IVI (HR, 2.60; P = .010), higher IOP elevation after the first injection (HR, 1.18/mm Hg; P = .011), and increased dosage of STI (HR, 1.07/mm Hg; P = .033) were risk factors. CONCLUSIONS: Younger age, higher baseline IOP, IVI, and increased TA dosage were associated with TA-induced IOP elevation. IOP elevation after repeated TA injection was frequently associated with eyes treated with IVI, high IOP elevation after the first injection, and high doses of STI.

Quantification of retinal nerve fiber layer thickness reduction associated with a relative afferent pupillary defect in asymmetric glaucoma.

AIM: The relative afferent pupillary defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. METHODS: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. RESULTS: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r(s) = -0.729, p<0.0001). Linear regression analysis found an equation that the average RNFL thickness ratio in the more affected eyes relative to that in the less advanced (%) = (0.827-0.169xRAPD (log units))x100 (R(2) = 0.557, p<0.0001). CONCLUSIONS: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

A case of POEMS syndrome with cystoid macular edema.

PURPOSE: To introduce a case of POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome with bilateral cystoid macular edema (CME). DESIGN: Interventional case report. METHODS: Temporal changes of serum vascular endothelial growth factor (VEGF) levels and macular thickness were evaluated. RESULTS: A 53-year-old woman with POEMS syndrome was referred complaining of long-standing impaired vision. Typical CME demonstrating petal-like dye pooling was observed in both eyes. After subtenon administrations of triamcinolone acetonide (TA), pars plana vitrectomy, and intraocular TA injection in the right eye, macular thickness decreased. Intraocular VEGF levels were <31 pg/ml at the vitrectomy and intraocular TA injection, whereas serum the VEGF level was >2000 pg/ml throughout the follow-up periods. In the untreated left eye, macular thickness altered related to serum VEGF level. CONCLUSIONS: Based on the low intraocular VEGF level and serum VEGF-related change of macular thickness, elevated serum VEGF might be a cause of CME in POEMS syndrome.

Retinal nerve fiber layer thickness in optic tract syndrome.

BACKGROUND: Optic tract syndrome (OTS) is characterized by incongruous homonymous hemianopia and a perpendicular pattern of bilateral optic atrophy due to the optic tract lesion. However, loss of retinal nerve fiber layer thickness (RNFLT) associated with OTS has not been quantitatively assessed. CASE: A 20-year-old woman with blunt head trauma showed normal visual acuity, color vision, ocular motility, and intraocular pressure. Because of a relative afferent pupillary defect in her left eye and left-sided homonymous hemianopia, we suspected right-sided optic tract damage, although magnetic resonance imaging detected no intracranial lesion. OBSERVATIONS: Using optical coherence tomography (OCT), the RNFLT of this case was measured at 31 months after the trauma and compared with age-matched normal controls (n = 41). Nasal, temporal, superior, and inferior quadrant RNFLT was reduced by 22%, 21%, 5%, and 46% in the right eye and 76%, 64%, 25%, and 27% in the left eye, respectively. The reduction was > 3 x the standard deviation of the normal mean values in the nasal and temporal quadrants of the left eye and in the inferior quadrant of the right eye. CONCLUSIONS: OCT can determine the RNFLT reduction corresponding to the characteristic patterns of optic atrophy of OTS.

Optical coherence tomography detects characteristic retinal nerve fiber layer thickness corresponding to band atrophy of the optic discs.

OBJECTIVES: To analyze retinal nerve fiber layer (RNFL) thickness in eyes with band atrophy by use of optical coherence tomography (OCT) and to evaluate the ability of OCT to detect this characteristic pattern of RNFL loss. DESIGN: Cross-sectional, retrospective study. PARTICIPANTS: Thirty-four eyes of 18 patients with bitemporal hemianopia caused by optic chiasm compression by chiasmal tumors were studied. All eyes were divided into 3 groups according to visual field loss grading after Goldmann perimetry. INTERVENTIONS: Retinal nerve fiber layer thickness measurements with OCT. MAIN OUTCOME MEASURES: Retinal nerve fiber layer thickness around the optic disc was measured by OCT (3.4-mm diameter circle). Calculation of the changes in OCT parameters, including the horizontal (nasal + temporal quadrant RNFL thickness) and vertical values (superior + inferior quadrant RNFL thickness) was based on data from 160 normal eyes. Comparison between the 3 visual field grading groups was done with the analysis of variance test. The receiver operating characteristic (ROC) curve for the horizontal and vertical value were calculated, and the areas under the curve (AUC) were compared. RESULTS: Retinal nerve fiber layer thickness in eyes with band atrophy decreased in all OCT parameters. The reduction rate in average and temporal RNFL thickness and horizontal value was correlated with visual field grading. The AUC of horizontal value was 0.970+/-0.011, which was significantly different from AUC of vertical value (0.903+/-0.022). CONCLUSIONS: The degree of RNFL thickness reduction correlated with that of visual field defects. Optical coherence tomography was able to identify the characteristic pattern of RNFL loss in these eyes.

Akt is activated via insulin/IGF-1 receptor in rat retina with episcleral vein cauterization.

The Akt serine/threonine kinase mediates pro-survival signalings in retina and was reported to be activated in a response to some retinal and optic nerve injuries. Human and experimental glaucoma induce apoptosis of retinal ganglion cells (RGCs). The purpose of this study is to test whether episcleral vein cauterization (EVC) to chronically elevate intraocular pressures (IOPs) in rats increase apoptosis of RGCs and affect activation of Akt and its upstream insulin-like growth factor (IGF)-1 receptor/Insulin receptor. Three episcleral veins in left eyes of Sprague-Dawley rats were cauterized to elevate IOPs. Up to 6 months, IOPs were monitored and the retina was dissected at several time points. The numbers of terminal dUTP nick end labeling (TUNEL)-positive cells and those of RGCs labeled with fluorogold were counted in flat-mounted retina. Immunohistochemistry and immunoblotting were performed to identify cells expressing phosphorylated Akt and to quantify the phospho- to total ratios of Akt and IGF-1 receptor/insulin receptor. EVC significantly elevated IOPs up to 2 months, increased TUNEL-positive cells in an IOP-dependent fashion, and reduced 34.5% of RGCs at 6 months (P<0.001) compared with contralateral retinas. Phosphorylated Akt was specifically expressed in RGCs until 1 month after cauterization. Akt (P=0.036) and IGF-1 receptor/Insulin receptor (P=0.003) were transiently phosphorylated at 3 days. Intrinsic activation of the IGF-1 receptor/Insulin receptor to Akt pathway may occur in RGCs in retina with EVC.

Prediction of postoperative visual outcome based on hole configuration by optical coherence tomography in eyes with idiopathic macular holes.

PURPOSE: To evaluate whether an index based on hole configuration can be used to predict visual outcome in eyes with idiopathic macular holes. DESIGN: Prospective interventional case series. METHODS: Thirty-five eyes of 32 patients with idiopathic stage 2 or 3 macular hole were enrolled in this study. The best-corrected visual acuity (BCVA), cross-sectional image of the macular hole by optical coherence tomography (OCT), and retinal thickness in the central (<1000 microm), inner (1000 to 2220 microm), and outer ring areas (2220 to 3450 microm) as defined by the OCT retinal mapping program were evaluated preoperatively and at 1, 3, 6, and 12 months postoperatively. The change in retinal thickness of the inner ring area at the 6-month postoperative period was used to evaluate the degree of preoperative retinal deformation. The macular hole index (MHI) (ratio of hole height to base diameter of hole) was calculated and correlated with minimum diameter of hole, base diameter of hole, the postoperative decrease in macular thickness, and the postoperative BCVA. The postoperative BCVA was further evaluated in two patient-matched groups. RESULTS: Retinal thickness values in the inner ring area were decreased at the 1-month postoperative period. MHI significantly correlated with the postoperative decrease in macular thickness in the inner ring area at 6 months (correlation coefficient = -0.632, P = .030, Spearman analysis) and with the postoperative BCVA (P = .013, multiple regression analysis). Postoperative BCVA in the MHI >/=0.5 group was better than that in the MHI <0.5 group (P = .032, Mann-Whitney test). CONCLUSIONS: The MHI is a ratio easily calculated from OCT transverse images of the macular area. The MHI represents the preoperative configuration of a macular hole and is a prognostic factor for visual outcome.

[Natural killer-cell lymphoma of the iris with a normal fundus].

BACKGROUND: Intraocular lymphoma is a relatively uncommon malignancy, rarely presenting with exclusively anterior segment findings in a normal fundus. CASE: A 38-year-old male, previously diagnosed with nasal lymphoma, currently in complete remission after chemotherapy and radiotherapy, presented with blurring of vision in his left eye, which initially responded to local steroid therapy. However, the patient developed resistance to steroid therapy and developed nodular masses in the left iris. Ultrasound biomicroscopy revealed diffuse thickenings leading to a complex and uneven shape of the left iris. An iris biopsy was done which led to the diagnosis of natural killer(NK)-cell lymphoma. Radiation therapy was instituted which led to rapid resolution of both the nodular masses and iritis. CONCLUSION: This is a case of malignant lymphoma presenting as metastasis to the iris without involvement of the chorioretinal tissues. When encountering a patient with iritis resistant to the steroid therapy, clinical ophthalmologists should consider metastatic malignancy in the differential diagnosis.

Nipradilol protects rat retinal ganglion cells from apoptosis induced by serum deprivation in vitro and by diabetes in vivo.

PURPOSE: To investigate if nipradilol has an anti-apoptotic effect in serum-deprived RGC-5 cells and in the streptozotocin-induced diabetic rat retina. METHODS: Apoptosis was quantified by activated caspase-3 immunohistochemistry or terminal dUTP nick end-labeling assay. RESULTS: Nipradilol dose-dependently suppressed apoptosis in a protein kinase A- and G-dependent manner and counteracted glutamate-induced calcium entry in the RGC-5 cells and reduced apoptotic cells in the retinal ganglion cell layer of 4- and 12-week diabetic retinas compared to controls when instilled for 5 days. Removal of the nitric oxide moiety from nipradilol blocked these effects. CONCLUSIONS: Nipradilol protects RGCs from apoptosis induced by serum-deprivation in vitro and by diabetes in vivo. The NO-related signaling pathway mediates the anti-apoptotic ability of nipradilol.

Latanoprost rescues retinal neuro-glial cells from apoptosis by inhibiting caspase-3, which is mediated by p44/p42 mitogen-activated protein kinase.

The purpose of this study was to investigate whether latanoprost, a prostaglandin F2alpha analogue, has a direct anti-apoptotic effect both in retinal neuro-glial cells in culture and in diabetic retina. R28 cells, immortalized retinal neuroglial progenitor cells, were induced apoptosis by 24h serum deprivation. Serum withdrawal made up to 15% of R28 cells pyknotic and activated caspase-3 immunoreactive, and latanoprost acid suppressed apoptosis with dose dependency at an optimum concentration of 1.0 microM (P<0.001). UO126, a mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase kinase (MEK) 1 and 2 inhibitor reversed this effect. Streptozotocin induced one- or three-month diabetic rats received balanced-salt-solution (BSS) in the left eye and latanoprost eye drops in the right for 5 days. Retinal wholemount was subjected to terminal dUTP nick end labeling (TUNEL) staining, whereas eyeballs were enucleated for cleaved caspase-3 immunofluorescence. Retinal homogenates were probed for phospho- or total p44/p42 MAPK and Akt. One- and three-month diabetic retina had 30.2+/-15.3 and 23.6+/-9.0 TUNEL positive cells per 0.5 cm(2), respectively, whereas control retina had few TUNEL positive cells. Latanoprost instillation significantly reduced these cells (10.0+/-3.1 and 11.3+/-3.1 cells per 0.5 cm(2) for 1M and 3M, respectively, P<0.01), whereas BSS did not. Latanoprost also significantly reduced cleaved caspase-3 immunoreactive cells in ganglion cell and inner nuclear layers (P<0.05). Latanoprost increased phosphorylated to total protein ratio of p44/p42 MAPK (P<0.05), but not of Akt. Taken together, the present findings suggest that latanoprost rescues retinal neurons and/or glial cells from apoptosis, which is probably mediated by p44/p42 MAPK through caspase-3 inhibition.

Quantification of retinal nerve fiber layer thickness reduction associated with a relative afferent pupillary defect.

BACKGROUND: A relative afferent pupillary defect (RAPD) is known to develop only when more than 25% of retinal ganglion cells are ablated in monkeys' eyes. However, there was no prior study to estimate biometrically the degree of retinal nerve fiber layer (RNFL) thickness reduction leading to the development of RAPD in live human eyes. The purpose of this study was to examine the correlation between the amount of RNFL thickness reduction and the depth of a clinically detectable RAPD in patients with unilateral optic atrophy. METHODS: Enrolled were 20 patients with optic atrophy of various etiologies. We quantified RAPD by performing the swinging flashlight test with log-scaled neutral density filters placed over the unaffected eye. Average RNFL thickness was measured by OCT3000 with the average RNFL thickness program. Linear regression analysis was used in assessing the relationship between RAPD and the ratio of affected to unaffected average RNFL thickness. RESULTS: The mean of average RNFL thickness was 95.6+/-17.3 microm in the unaffected eyes and 50.7+/-19.3 microm in the affected eyes (P<0.001). Regression analysis between RAPD and the ratio of affected to unaffected average RNFL thickness revealed a correlation coefficient R2=0.48 (P=0.0007). The regression line intersected the y-axis at 0.77. CONCLUSIONS: RAPD was not clinically detected until at least approximately 25% of the retinal nerve fibers were lost when compared with the unaffected eyes. Substantial retinal ganglion cell damage is required for the development of RAPD.

Long-term glial reactivity in rat retinas ipsilateral and contralateral to experimental glaucoma.

Although glaucoma is known to alter glial reactivity, the long-term effect of elevated intraocular pressure (IOP) on glial change has not been fully elucidated. This study aimed to examine how chronically elevated IOP induced by episcleral vein cauterization (EVC) in unilateral eyes affect reactivities of astrocytes and Müller cells of rats in the treated as well as contralateral eyes over time. EVC in unilateral eyes of Sprague-Dawley rats were performed to produce chronically elevated IOP. Flat mounted retina preparations were made at several points until 6 months, which were subjected to immunostaining for glial fibrillary acidic protein (GFAP). Retinal homogenates were one- or two-dimensionally electrophoresed, followed by GFAP immunoblotting. EVC significantly increased IOPs up to 27.8 from 13.1 mmHg, which gradually decreased over time. In flat mounted retinas, astrocytes lost but Müller cells gained GFAP immunoreactivity at 3 days after cauterization. The glial changes were partially reversed over time but last even after IOP normalization. In the contralateral eyes, similar glial changes gradually appeared at 1 month after EVC and thereafter. Immunoblotting demonstrated not only molecular size shifts but also alteration of isoelectric focusing of GFAP both in treated and contralateral retina as compared with age-matched control retina. EVC led to opposite reactions in astrocytes and Müller cells in terms of GFAP immunoreactivity. Late-onset glial reactivity also occurred in the contralateral retina.