Total Retinal Thickness Research Articles

The use of OCT to detect signs of intracranial hypertension in patients with sagittal suture synostosis: Reference values and correlations

PurposeTo obtain pediatric normative reference values and determine whether optical coherence tomography (OCT) corresponds better with clinical signs of intracranial hypertension (ICH) compared to the traditional screening method fundoscopy in a large cohort of one type of single suture craniosynostosis.MethodsControl subjects without optic nerve diseases and isolated sagittal synostosis patients aged 3–10 years who underwent fundoscopy and OCT were included in this prospective cohort study. Normative reference values were obtained through bootstrap analysis. Main outcome was the association between peripapillary total retinal thickness (TRT) and total retinal volume (TRV) and appearance on fundoscopy. Signs and symptoms suggestive of ICH, including skull growth arrest, fingerprinting, and headache, were scored.ResultsSixty-four healthy controls and 93 isolated sagittal synostosis patients were included. Normative cut-off values for mean TRT are < 256 μm and > 504 μm and for mean TRV < 0.21 mm3 and > 0.39 mm3. TRT was increased in 16 (17%) and TRV in 15 (16%) of 93 patients, compared to only 4 patients with papilledema on fundoscopy (4%). Both parameters were associated with papilledema on fundoscopy (OR = 16.7, p = 0.02, and OR = 18.2, p = 0.01). Skull growth arrest was significantly associated with abnormal OCT parameters (OR = 13.65, p < 0.01).ConclusionsThe established cut-off points can be applied to screen for ICH in pediatrics. The present study detected abnormalities with OCT more frequent than with fundoscopy, which were associated with skull growth arrest. Therefore, a combination of OCT, fundoscopy, and skull growth arrest can improve clinical decision-making in craniosynostosis.

Protective Effects of the Bilobalide on Retinal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Rats.

Diabetic retinopathy (DR) is a diabetes mellitus (DM) complication that causes visual acuity impairment and loss of sight in the working population, mainly in developed countries. According to the WHO, DR accounts for 5% of the world's 37 million blind people. The prevalence of diabetic retinopathy was highest in Africa, followed by North America and the Caribbean and South and Central America. Hyperglycemia can generate excessive ROS that activates multiple pathways, which can damage the cells. Oxidative stress and inflammatory process are intricate in the DR pathological mechanism. Bilobalide is the main bioactive compound isolated from the Ginkgo biloba, a plant utilized in folklore medicine. Bilobalide, a sesquiterpene trilactone, exhibits excellent antioxidant activity. But the molecular mechanisms associated with such effects, especially the antioxidant-related mechanism, have not been documented. Hence, this investigation explored whether bilobalide may attenuate DR in streptozotocin (STZ)-prompted diabetic rats. The effects of bilobalide on parameters of antioxidant content, oxidative stress, and inflammatory factors in the retinal tissues were evaluated by ELISA, RT-PCR, and immunohistochemistry methods. Bilobalide improved caloric management by reducing food consumption and increasing body weight. Furthermore, the administration of bilobalide decreases the blood glucose level and glycosylated (HbA1c) hemoglobin. The anti-retinopathy activity of bilobalide was established by the increase in the total retina thickness (TRT), inner nuclear layer (INL), and outer nuclear layer (ONL) in diabetic rats. Additionally, the serum level of MDA was decreased. In contrast, the antioxidant enzyme (SOD and CAT) levels were increased with TAC plus lower Keap1 and higher Nrf2 expression in the retina when associated with the DM rats. Moreover, bilobalide increased the nuclear factor erythroid 2-related factor 2 (Nrf2) and Heme oxygenase-1 (HO-1) expression level and inflammatory mediators (NF-κβ p65, TNF-α, IL-1β, and VEGF), thus inhibiting oxidative stress. Bilobalide can be effective against DR, and the possible mechanism may be relatively elucidated by decreasing oxidative stress and anti-inflammatory activities. But the further investigation should be directed to expose the precise mechanism.

Association of self-reported snoring with decreased retinal thickness and vessel density.

Purpose: Self-reported snoring has been reported to influence nerves and vessels. However, there are few direct evidences of snoring related to nerves and microvessels defects. Therefore, we evaluated the association of self-reported snoring with retinal structure and microcirculation. Methods: A total of 2,622 participants were recruited from the Jidong eye cohort study (JECS). Physical examinations, laboratory tests, and questionnaires were recorded. We also used optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) to assess the retinal structure and microvascular network. Snoring was defined as “never,” “occasionally,” and “frequently or more severe” according to self-reported frequency. Results: The prevalence of snoring were 84.6% (n = 983) and 45.0% (n = 657) in males and females, respectively. Compared with never snoring group, the retinal thickness increased in “occasionally” (p < 0.001) and “frequently or more severe” groups (p = 0.001), while no difference was found between snoring groups (p = 0.14). Superficial retinal capillary plexus (RCP) vessel density was lower in “frequently or more severe” group than in “never” (p < 0.001) and “occasionally” snoring groups (p < 0.001). After adjusting for confounders, “frequently or more severe” snoring was significantly associated with thinner total retinal thickness [β = −2.79 (95% CI: −5.27, −0.30)] and lower superficial RCP vessel density [β = −0.71 (95% CI: −1.19, −0.23)]. Conclusion: Our research showed self-reported snoring was associated with thinner retinal thickness and lower superficial RCP vessel density. The findings of our study emphasize the need for self-reported snoring assessments in determining retinal structure and microcirculation impairment.

The thickness of the outer retina in the macula and circumpapillary area in patients with unilateral advanced glaucoma.

To compare outer macular and retinal thickness in the circumpapillary area in unilateral advanced glaucomatous eyes to the normal or mild glaucomatous fellow eyes. Seventy-eight eyes of 39 patients with unilateral advanced glaucoma (mean deviation (MD) worse than -12.00 dB based on visual field 24-2) were included in this cross-sectional study as the cases. The healthy or mild glaucomatous fellow eyes were enrolled as the control group. All eyes underwent optical coherence tomography of the macula and circumpapillary retina by Topcon DRI Triton (Topcon, Tokyo, Japan). Ganglion cell layer 2+ was considered as the inner retina. Total retinal thickness minus the thickness of the inner retina was considered as the outer retina. Comparison between groups was done by paired-sample sign test. The correlation between structural and functional parameters was evaluated by a partial correlation coefficient. Seventeen (43.6%), 15 (38.5%), and 7 (17.9%) patients had pseudoexfoliation, primary angle-closure, and primary open-angle glaucoma, respectively. The mean age was 62.69 ± 12.00 years. Thirty-three (84.6%) patients were male. The outer retinal thickness in the circumpapillary area was higher in temporal, superior, and inferior quadrants (p < 0.05). The outer macula in different parafoveal and perifoveal quadrants was also thicker (p < 0.05). Average outer parafoveal thickness in the case group had a significant negative correlation with MD (r = -0.339; p = 0.035). Advanced glaucomatous eyes had a thicker outer retina in the macula and circumpapillary area. There was a significant negative correlation between outer perifoveal thickness and MD.

Retrospective analysis of OCT parameters after intravitreal anti-VEGF inhibitors in neovascular AMD patients in a real-world setting

PurposeThe aim of the present study was to evaluate changes of best corrected visual acuity (BCVA), retinal nerve fiber layer thickness (RNFL), total macular volume (TMV), intraocular pressure (IOP) and central retinal thickness (CRT) after intravitreal injection of ranibizumab, bevacizumab and aflibercept in patients with neovascular age-related macular degeneration (nAMD) in a clinical real world setting.MethodsIn a retrospective clinical study design, 120 patients (80 women and 40 men) were analyzed after being diagnosed with nAMD within 8 years (2010–2018). Every patient received at least 6 anti-VEGF injections in a Pro-Re-Nata or Treat-and-Extend regimen. OCT parameters (RNFL, TMV, CRT) and visual acuity (BCVA) were assessed at first diagnosis, at treatment day and during the course.ResultsIntraretinal fluid was reduced significantly in a magnitude of 88–64 µm (CRT) and 0.75–0.55 mm3 (TMV). Apart from a significant reduction immediately after the therapy start (post-3 injections) with ranibizumab (− 1.4 µm, p = 0.03), RNFL thickness remained constant. A slight improvement in visual acuity of 0.06 logMAR could initially be observed. If further injections were required, only stabilization was achieved compared to baseline visual acuity.ConclusionThe changes of OCT parameters CRT, TMV, and RNFL as well as the stabilization of functional results (BCVA) as illustrated in this study comparing effects of different anti-VEGF-agents provide evidence for the transferability of former results to a clinical real-world setting.

Measurement of the Inner Macular Layers for Monitoring of Glaucoma: Confounding Effects of Age-Related Macular Degeneration

To investigate the confounding effect of nonexudative age-related macular degeneration (AMD), specifically drusen and outer retinal atrophy, on the architecture and automated segmentation of the inner retinal layers as measured with OCT. Observational cross-sectional study. Two hundred sixty-three consecutive eyes with nonexudative AMD were identified through a retrospective chart review. Exclusion criteria were a diagnosis of glaucoma or glaucoma suspect, other retinal pathology affecting the macula, axial length > 26.5 mm or spherical equivalent less than -6 diopters, any other optic nerve or neurologic disorders, or poor image quality. Drusen were automatically segmented on macular OCT B-scans with a publicly available and validated deep learning approach. Automated segmentation of the inner plexiform layer (IPL)/inner nuclear layer (INL) boundary was carried out with the device's proprietary software. Quality of segmentation of the IPL/INL boundary as a function of drusen size and presence of inner retinal layer displacement in the area of macular pathology (drusen or atrophy). One hundred twenty-five eyes (65 patients) met the inclusion criteria. Drusen size varied between 16 and 272 μm (mean, 118 μm). Automated segmentation had a 22% chance of failure if the drusen height was between 145 and 185 μm and was most likely to fail with drusen heights above 185 μm. When drusen height was normalized by total retinal thickness, segmentation failed 36% of the time when the drusen to total retinal thickness ratio was 0.45 or above. Images were likely to show displacement of inner retinal layers with drusen heights above 176 μm and a normalized drusen height ratio of 0.5 or higher. Eighty-seven percent of images with outer retinal atrophy displayed incorrect segmentation. Outer retinal diseases can alter the retinal topography and affect the segmentation accuracy of the inner retinal layers. Large drusen may cause segmentation error and compression of the inner macular layers. Geographic atrophy confounds automated segmentation in a high proportion of eyes. Clinicians should be cognizant of the effects of outer retinal disease on the inner retinal layer measurements when interpreting the results of macular OCT imaging in patients with glaucoma.

Changes in Optic Nerve Head and Retinal Morphology During Spaceflight and Acute Fluid Shift Reversal

Countermeasures that reverse the headward fluid shift experienced in weightlessness have the potential to mitigate spaceflight-associated neuro-ocular syndrome. This study investigated whether use of the countermeasure lower-body negative pressure during spaceflight was associated with changes in ocular structure. To determine whether changes to the optic nerve head and retina during spaceflight can be mitigated by brief in-flight application of 25-mm Hg lower-body negative pressure. In the National Aeronautics and Space Administration's "Fluid Shifts Study," a prospective cohort study, optical coherence tomography scans of the optic nerve head and macula were obtained from US and international crew members before flight, in-flight, and up to 180 days after return to Earth. In-flight scans were obtained both under normal weightless conditions and 10 to 20 minutes into lower-body negative pressure exposure. Preflight and postflight data were collected in the seated, supine, and head-down tilt postures. Crew members completed 6- to 12-month missions that took place on the International Space Station. Data were analyzed from 2016 to 2021. Spaceflight and lower-body negative pressure. Changes in minimum rim width, optic cup volume, Bruch membrane opening height, peripapillary total retinal thickness, and macular thickness. Mean (SD) flight duration for the 14 crew members (mean [SD] age, 45 [6] years; 11 male crew members [79%]) was 214 (72) days. Ocular changes on flight day 150, as compared with preflight seated, included an increase in minimum rim width (33.8 μm; 95% CI, 27.9-39.7 μm; P < .001), decrease in cup volume (0.038 mm3; 95% CI, 0.030-0.046 mm3; P < .001), posterior displacement of Bruch membrane opening (-9.0 μm; 95% CI, -15.7 to -2.2 μm; P = .009), and decrease in macular thickness (fovea to 500 μm, 5.1 μm; 95% CI, 3.5-6.8 μm; P < .001). Brief exposure to lower-body negative pressure did not affect these parameters. Results of this cohort study suggest that peripapillary tissue thickening, decreased cup volume, and mild central macular thinning were associated with long-duration spaceflight. Acute exposure to 25-mm Hg lower-body negative pressure did not alter optic nerve head or retinal morphology, suggesting that longer durations of a fluid shift reversal may be needed to mitigate spaceflight-induced changes and/or other factors are involved.

Two-year longitudinal study on changes in thickness of the retinal nerve fiber layer and ganglion cell layer in children with type 1 diabetes mellitus without visual impairment or diabetic retinopathy

Purpose To study changes in the thickness of the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) in children with type 1 diabetes mellitus (T1DM) without visual impairment or diabetic retinopathy (DR) after 2 years of follow-up and analyze the associated factors. Methods Thirty-seven children with T1DM were enrolled in this study. All children underwent a complete ophthalmologic evaluation that included swept-source optical coherence tomography at baseline and follow-up. Changes in RNFL and GCL thickness were compared among the children at baseline and follow-up. Results The peripapillary RNFL thickness was greater in the temporal (inner, p = 0.015; outer, p = 0.004) and inner superior (p = 0.043) sectors in the follow-up group than in the baseline group. The macular RNFL thickness in the fovea, inner nasal sector, inner inferior sector, and outer ring and the average thickness (all p < 0.05) were greater in the follow-up group than in the baseline group. The peripapillary GCL thickness decreased in the temporal sector (inner, p = 0.049; outer, p = 0.041) and increased in the inner nasal sector (p = 0.006) in the follow-up group compared with the baseline group, and the thickness of the inner temporal, inner superior, inner inferior, outer nasal, and outer inferior sectors and average thickness in the macula were lower in the follow-up group than in the baseline group (all p < 0.05). The total retinal thickness around optic disc in the follow-up group increased in the inner superior sectors (p = 0.006). The total retinal thickness of the macula decreased in inner temporal sector, inner superior sector and outer nasal sector, and increased in outer superior sector (all p < 0.05). Conclusions Retinal neurodegenerative changes preceded microvascular changes in children with T1DM in the early stage. Peripapillary RNFL thickness in the nasal sector may be lower in children with T1DM without visual impairment or other ocular pathologies.

The macular inner plexiform layer thickness as an early diagnostic indicator for Parkinson’s disease

Whether structural alterations of intraretinal layers are indicators for the early diagnosis of Parkinson’s disease (PD) remains unclear. We assessed the retinal layer thickness in different stages of PD and explored whether it can be an early diagnostic indicator for PD. In total, 397 [131, 146, and 120 with Hoehn-Yahr I (H-Y I), H-Y II, and H-Y III stages, respectively] patients with PD and 427 healthy controls (HCs) were enrolled. The peripapillary retinal nerve fiber layer (pRNFL), total macular retinal thickness (MRT), and macular volume (TMV) were measured by high-definition optical coherence tomography, and the macular intraretinal thickness was analyzed by the Iowa Reference Algorithms. As a result, the PD group had a significantly lower average, temporal quadrant pRNFL, MRT, and TMV than the HCs group (all p < 0.001). Moreover, the ganglion cell layer (GCL), inner plexiform layer (IPL), and outer nuclear layer were thinner in patients with PD with H-Y I, and significantly decreased as the H-Y stage increased. In addition, we observed that GCL and IPL thicknesses were both correlated with Movement Disorder Society-Unified Parkinson’s Disease Rating Scale III (MDS-UPDRS III) scores and non-motor symptoms assessment scores. Furthermore, macular IPL thickness in the superior inner (SI) quadrant (IPL-SI) had the best diagnostic performance in patients with PD with H-Y I versus HCs, with a sensitivity and specificity of 75.06% and 81.67%, respectively. In conclusion, we confirmed the retinal structure was significantly altered in patients with PD in different clinical stages, and that GCL and IPL changes occurred during early PD disease and were correlated with MDS-UPDRS III scores and non-motor symptoms assessment scores. Furthermore, macular IPL-SI thickness might be performed as an early diagnostic indicator for PD.

Quantitative and qualitative characterization of retinal dystrophies in canine models of inherited retinal diseases using spectral domain optical coherence tomography (SD-OCT)

The purpose of this study was to establish spectral domain optical coherence tomography (SD-OCT) assessment data in well-established canine models of inherited retinal dystrophies: PDE6B-rod-cone dysplasia 1 (RCD1: early onset retinitis pigmentosa), PRCD-progressive rod-cone degeneration (PRCD: late onset retinitis pigmentosa), CNGB3-achromatopsia, and RPE65-Leber congenital amaurosis (LCA). High resolution SD-OCT images of the retina were acquired from both eyes in 5 planes: temporal; superotemporal; superior; nasal; and inferior in adult dogs with: RCD1 (n = 4 dogs, median age: 1.5 yrs); PRCD (n = 2, 4.3 yrs); LCA (n = 3, 5.2 yrs); achromatopsia (n = 3, 4.2 yrs); and wild types (wt, n = 6, 5.5 yrs). Total, inner and outer retinal thicknesses and ellipsoid zone were analyzed. In selected animals, histomorphometric evaluations were performed. In dogs with RCD1, PRCD, and LCA, the thickness of the outer retina was, compared to wt, significantly decreased (p ≤ 0.02) in all OCT imaging planes, and in superotemporal and inferior imaging planes in dogs with achromatopsia. No significant thinning was observed in inner retina thickness in any disease model except in the inferior imaging plane in dogs with RCD1. Dogs with RCD1, PRCD, and LCA had significantly more areas with disrupted ellipsoid zone in the presumed area centralis than wt (p ≤ 0.001). OCT findings provide baseline information for research of retinal dystrophies using these canine models.

Decreased Expression of Glial-Derived Neurotrophic Factor Receptors in Glaucomatous Human Retinas

Purpose The purpose of this study was to examine the expression of glial-derived neurotrophic factor (GDNF), the GDNF receptors GFRα1 and GFRα2, ciliary neurotrophic factor (CNTF), and the CNTF receptor CNTFRα in normal and glaucomatous human tissue. Methods Human retinas were collected from 8 donors that had been clinically diagnosed and treated for glaucoma, and also from 9 healthy control donors. Immunohistochemical analysis for each trophic factor and receptor was performed. The percent of each retinal section labeled with each antibody was quantified for the total retinal thickness, and separately for the retinal ganglion cell (RGC) complex + retinal nerve fiber layer (RNFL). The expression of each protein was correlated with measures of the subject’s ocular histories. Results The percentage area immunopositive for GFRα2 was significantly decreased in the total retinal thickness containing all retinal layers and in the combined RGC complex + RNFL in glaucomatous eyes in both the peripapillary region and more peripheral retinal locations. We also observed a decrease in GFRα1 expression in the peripapillary RGC Complex + RNFL in glaucoma patients compared to healthy control patients. We also observed a relationship between GDNF and its receptors with several outcomes obtained from the medical record. No differences in CNTF or CNTFR labeling were observed. Conclusion Decreases in GDNF receptor expression in glaucomatous tissue may limit the potential for neuroprotective therapy by supplementation with GDNF.

Cone Photoreceptors in Diabetic Patients.

PurposeCones in diabetic patients are at risk due to metabolic and vascular changes. By imaging retinal vessel modeling at high magnification, we reduced its impact on cone distribution measurements. The retinal vessel images and retinal thickness measurements provided information about cone microenvironment.MethodsWe compared cone data in 10 diabetic subjects (28–78 yr) to our published norms from 36 younger and 10 older controls. All subjects were consented and tested in a manner approved by the Indiana University Institutional Review Board, which adhered to the Declaration of Helsinki. Custom adaptive optics scanning laser ophthalmoscopy (AOSLO) was used to image cones and retinal microcirculation. We counted cones in a montage of foveal and temporal retina, using four non-contiguous samples within 0.9–7 deg that were selected for best visibility of cones and least pathology. The data were fit with a two parameter exponential model: ln(cone density) = a * microns eccentricity + b. These results were compared to retinal thickness measurements from SDOCT.ResultsDiabetic cone maps were more variable than in controls and included patches, or unusually bright and dark cones, centrally and more peripherally. Model parameters and total cones within the central 14 deg of the macula differed across diabetic patients. Total cones fell into two groups: similar to normal for 5 vs. less than normal for 2 of 2 younger diabetic subjects and 3 older subjects, low but not outside the confidence limits. Diabetic subjects had all retinal vascular remodeling to varying degrees: microaneurysms; capillary thickening, thinning, or bends; and vessel elongation including capillary loops, tangles, and collaterals. Yet SD-OCT showed that no diabetic subject had a Total Retinal Thickness in any quadrant that fell outside the confidence limits for controls.ConclusionsAOSLO images pinpointed widespread retinal vascular remodeling in all diabetic eyes, but the SDOCT showed no increased retinal thickness. Cone reflectivity changes were found in all diabetic patients, but significantly low cone density in only some. These results are consistent with early changes to neural, glial, or vascular components of the retinal without significant retinal thickening due to exudation.

Hydroxychloroquine treatment alters retinal layers and choroid without apparent toxicity in optical coherence tomography

Background To investigate whether single retinal layer, choroidal and peripapillary retinal fiber layer thicknesses were affected in patients under hydroxychloroquine treatment without retinal toxicityMethods Forty-nine patients under hydroxychloroquine treatment (HCQ group) and 39 healthy volunteers, a total of 88 individuals, were included in the study. Patients with HCQ treatment were further divided into two groups as less than 5 years of HCQ use (group 1, 29 patients) and 5 years or more of HCQ use (group 2, 20 patients). All participants underwent full ophthalmologic examination and optical coherence tomography (OCT) imaging as OCT is a recommended tool for screening toxicity by the American Association of Ophthalmology. The automatic segmentation of retinal layers included retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retina pigment epithelium (RPE), inner retinal layers (IRL), outer retinal layers (ORL) and total retina thickness (TRT). Choroidal thickness (ChT), choroidal vascularity index and peripapillary RNFL were also measured.Results Both inferior and nasal parafoveal RNFL, temporal parafoveal GCL, and IPL layer thicknesses were decreased, while temporal parafoveal RPE layer thicknesses were increased in hydroxychloroquine users. Subfoveal ChTs were significantly reduced in both groups 1 and 2 compared to the control group(p = 0.042 and p = 0.009, respectively) and temporal ChT thicknesses were statistically decreased in group 2 compared to the control group(p = 0.018), but not for nasal ChT.Conclusions Hydroxychloroquine use may cause parafoveal retinal layer thickness alterations and also subfoveal and parafoveal ChT alterations even without evident retinal toxicity in OCT.

Anti-CXCL10 monoclonal antibody therapy protects against the diabetic retinopathy in the mouse model induced by streptozotocin

ObjectiveTo explore the effect of CXC chemokine CXCL10 in the mice with diabetic retinopathy (DR). MethodsDR models were constructed on mice via injection of streptozotocin (STZ). At 3 weeks of STZ, mice were treated with anti-CXCL10 monoclonal antibodies (mAb)/control mAb, and a series of experiments were then conducted at 6 weeks of STZ, including HE staining, western blotting, retinal trypsin digestion, real-time qPCR and enzyme-linked immuno sorbent assay (ELISA). The corresponding kits were used to detect the activity of oxidative stress markers. ResultsCompared with nondiabetic eyes, DR mice both at 3 and 6 weeks presented the decreases in the total retinal thickness, the retinal outer nuclear layer (ONL) thickness, and the cells of ganglion cell layer (GCL), with the upregulated CXCL10, pro-inflammatory cytokines and malondialdehyde (MDA), as well as the downregulated levels of superoxide dismutase (SOD), glutathione peroxidase (GPx) and CAT, especially in those at 6 weeks, which were attenuated by the anti-CXCL10 mAb treatment. Moreover, in comparison with the DR mice, mice in the DR + anti-CXCL10 mAb group gained the significant decrease in the number of acellular capillaries of retina, with up-regulations of Claudin-5 and ZO-1 and down-regulations of VEGF and FGF-2. The DR mice injected with anti-CXCL10 mAb demonstrated alleviated retinal pathology as compared to mice at 3 weeks of STZ. ConclusionAnti-CXCL10 mAb could mitigate the retinal pathology of DR mice, with the decreased inflammation and oxidative stress, thus mediating a delay in the development or disease improvement in patients of DR.

Atropine Affects the Outer Retina During Inhibiting Form Deprivation Myopia in Guinea Pigs

ABSTRACT Purpose Atropine has been proven to be effective in retarding myopia progression. However, the underlying mechanism remains unknown. Our purpose was to detect morphological and functional changes caused by atropine during myopic inhibition. Method Twenty 2-week-old guinea pigs were randomly assigned to either the saline group (n = 10) or the atropine group (n = 10). Form-deprived myopia (FDM) and intravitreal injections were applied on the right eyes. The injections were given every 3 days, lasting for 2 weeks. The left eyes served as control. Ocular refraction, axial length, retinal, and choroidal thickness were collected at the start and the end of the experiment. Retinal function was evaluated via full-field electroretinogram (ERG) at the end of treatment. Results The interocular differences (experimental eye minus control eye) of refraction error (RE), vitreous chamber depth (VCD), and axial length (AL) in the saline group were significantly greater than those in the atropine group (RE, VCD: P < .001, AL: P < .0001). The differences in choroidal thickness between the two groups did not reach statistical significance. However, a decreasing trend of choroidal thickness was observed in the saline group but not in the atropine group. Furthermore, the interocular differences of total retinal and outer retinal thickness in the atropine group were much thicker than in the saline group (P < .001 and P < .01, respectively). The treatment did not affect inner retinal thickness. In photopic ERG, the atropine-treated FDM eyes showed significantly greater a-wave amplitudes compared to the saline group. Conclusion During the process of inhibiting FDM, atropine showed an effect on the outer retina, most likely on the cones, in guinea pigs.

Foveal Morphology of Normal Fellow Eyes of Patients with Unilateral Macular Hole

To determine the morphology of the fovea in the ophthalmoscopically and tomographically normal fellow eyes of patients with a unilateral idiopathic macular hole (MH) and determine the association between foveal morphological parameters and foveal outer nuclear layer (ONL) thickness. Retrospective observational study. Two hundred three normal fellow eyes of patients with a unilateral MH and 216 normal eyes of 216 healthy subjects. All the eyes were examined using swept-source OCT. A built-in software was used to measure the average retinal and choroidal thickness in the center and in the inner 4 subfields defined in ETDRS. The total retinal thickness, thickness of 3 retinal layers at the fovea and parafovea (0.25 and 0.5 mm nasal and temporal from the fovea), and foveal floor width (FFW) were measured on a scan image of a horizontal line passing through the center of the fovea. We defined the thickness between the internal limiting membrane and outer plexiform layer as inner retinal thickness and the thickness between the external limiting membrane and retinal pigment epithelium as outer retinal thickness. Multiple regression analyses were performed with age, sex, axial length, and the presence of a posterior vitreous detachment as the dependent variables. OCT measurements and correlations between foveal parameters and foveal ONL thickness. The fellow eyes had a thinner central retinal subfield, thinner fovea, thinner ONL at all points except at 0.5 mm nasal, significantly thicker outer retina at all points, and a wider FFW (P= 0.040 to P < 0.0001). The foveal ONL thickness was significantly and positively correlated with the central subfield retinal thickness and foveal thickness and negatively correlated with the FFW (all P < 0.0001). The thinner and deeper fovea and the thinner ONL of the fellow eyes of patients with a unilateral MH make these eyes more susceptible to the formation of an MH.

Diagnosis of Alzheimer's disease by analyzing the roughness of the retinal layers

AbstractPurposeAlzheimer’s Disease (AD) is the most common cause of dementia. Retinal thickness changes had been reported in different stages of the disease, being these changes a biomarker of AD progression. There is increasing evidence that thinned and thickened regions are interspersed throughout the retinal layers of AD patients, resulting in the roughness of their bounding surfaces and thickness maps. The aim of this work is to prove the roughness of retinal layers, as assessed by the fractal dimension (FD) of their thickness maps, is an early biomarker of AD.MethodsA complete ophthalmological exam and cognitive test (Mini Mental State Examination) was carried out in 24 healthy volunteers and 19 patients with mild AD. Total retinal thickness and retinal layers thickness were studied by optical coherence tomography (OCT) and thickness retinal maps were obtained. From the whole retinal area scanned on each subject only a central square region available from all sample subjects was kept for roughness analysis. In this square, the FD of the thickness map of each retinal layer was calculated as an index of its roughness.ResultsThe FD of retinal layers is significantly higher (p &lt; 0.05) in the AD group, compared to the healthy group. The correlation of FD with cognitive score, visual acuity and age reaches statistical significance in 7 layers. Nearly all (44 out of 45) FD correlations among layers are positive and half of them (23) reached statistical significance (p &lt; 0.05). Factor analysis revealed two groups of retinal layers whose roughness evolves independently: the first includes two layers related to the outer segments and may be influenced by dysregulation of the choroidal vascular network; and the second includes the remaining layers, and may be associated with the inflammatory process of the retina.ConclusionsRoughness is a holistic feature of retinal layers that can be assessed by FD of their thickness maps and is an early biomarker of AD.

Posterior Pole Asymmetry Analysis in the Children with Anisometropia.

Objectives:The objectives of the study were to investigate the inter and intraocular differences in posterior pole asymmetry analysis (PPAA) with optical coherence tomography (OCT) in anisometropia, to examine the relationship between the presence of anisometropia and amblyopia and retinal thickness.Methods:Patients between ages of 5 and 16 years with anisometropia who applied to our clinic were included in the study. Macular retinal thickness measurements were evaluated by PPAA using the posterior pole algorithm of the spectral domain-OCT device. Asymmetry was analyzed both as the difference between the right and left eyes and the difference between the superior, inferior, and mean retinal thicknesses of 64 separate quadrants in the same eye. Hemispheric and right-left eye asymmetry differences analyses were performed.Results:118 patients were included in the study(65 females and 53 males). Group 1 consisted of anisometropic patients (n=46), Group 2 consisted of anisometropic amblyopia patients (n=40), and Group 3 consisted of control group (n=32). The mean age of the patients was 9.72±5.6 years. The mean spherical equivalent difference between the two eyes of the patients was 1.7±0.6 D. When anisometropic eyes were compared with normal eyes, there was no significant difference between mean superior, inferior and total retinal thickness, and right-left eye asymmetry values (for all, p>0.05). In the asymmetry evaluation performed by counting the black boxes in the PPAA, a significant difference was found in the right-left asymmetry evaluation in anisometropic amblyopic eyes, in some quadrants and in the right-left asymmetry analysis (p<0.05).Conclusion:While no difference was found between anisometropic and normal eyes in the PPAA, there was differences in some quadrants in the anisometropic amblyopic group compared to the control group suggesting that there is an involvement in the peripheral quadrants of the macula, especially in treatment resistant amblyopic patients.

Cilostazol protects against changes caused by streptozotocin-induced diabetic retinopathy.

This study investigates the protective effect of cilostazol on the development and evolution of diabetic retinopathy in rats. Sixty male rats were divided into four groups: untreated nondiabetic rats, untreated diabetic rats, cilostazol-treated nondiabetic rats, and cilostazol-treated diabetic rats. The thickness of the internal limiting membrane to the outer limiting membrane, inner plexiform layer, inner nuclear layer, and outer nuclear layer were measured. The number of cell nuclei per 50-μm length in retinal sections was counted to quantify the degree of retinal cell loss. The number of nuclei in the ganglion cell layer was significantly higher in untreated nondiabetic rats (p<0.05). The mean number of nuclei in the cilostazol-treated nondiabetic rats was significantly higher than that in the cilostazol-treated diabetic rats (p<0.05). The cilostazol-treated nondiabetic rats had a significantly higher mean nuclei count in the inner nuclear layer and inner plexiform layer as compared with the other groups (p<0.05). The total mean retinal thickness of the cilostazol-treated nondiabetic rats was significantly higher than that of cilostazol-treated diabetic rats and untreated diabetic rats (p<0.05). By decreasing the loss of ganglion cells and reducing the sensorineural atrophy in the internal retinal layers, cilostazol had a protective effect against changes caused by diabetic retinopathy in diabetic rats.

Sex variation of central serous chorioretinopathy by spectral domain optical coherence tomography

Purpose The aim of this study was to compare the spectral domain optical coherence tomography (SD-OCT) characteristics of central serous chorioretinopathy (CSR) between male and female patients.Patients and methods This is a retrospective study that included 39 patients of both sexes diagnosed as CSR during the period between January 2018 and May 2020. The analyzed data included patients’ age, duration of symptoms, and the SD-OCT measurable parameters in the male and female patient groups. The SD-OCT parameters included central total retinal thickness, central sensory retinal thickness, vertical distance of subfoveal subretinal fluid, horizontal distance of subfoveal subretinal fluid, and the presence of subretinal deposits. These parameters were compared and statistically analyzed between the two groups.Results The study included 24 male patients and 15 female patients. The mean age was 35.33±9.88 years in the male group and 41.53±8.28 years in the female group (P=0.05). In the male group, central total retinal thickness, central sensory retinal thickness, vertical distance of subfoveal subretinal fluid, and horizontal distance of subfoveal subretinal fluid were 448±93 μm, 182±34 μm, 305±53 μm, and 3.07±0.63 mm, respectively, while in the female group, they were 346±127 μm (P=0.006), 178±34 μm (P=0.73), 244±61 μm (P=0.002), and 2.34±0.67 mm (P=0.001), respectively. The percentage of patients having subretinal deposit was significantly more in the male group than in the female group (P=0.003).Conclusions There was a statistically significant difference in SD-OCT characteristics of CSR between male and female patients. Further studies are needed regarding the persistence of these OCT differences after treatment of CSR.