Total Retinal Thickness Research Articles

Custom Optical Coherence Tomography Parameters for Distinguishing Papilledema from Pseudopapilledema.

Causes of papilledema can be life-threatening; however, distinguishing papilledema from pseudopapilledema is often challenging. The conventional optical coherence tomography (OCT) scan for assessing the optic nerve often fails to detect mild papilledema. Our study suggests that parameters derived from volumetric OCT scans can provide additional useful information for detecting papilledema. Optical coherence tomography analysis of the optic nerve commonly measures retinal nerve fiber layer thickness (RNFLT) along a 1.73-mm-radius scan path. This conventional scan, however, often fails to detect mild papilledema. The purpose of this study was to evaluate additional OCT-derived measures of the optic nerve head (ONH) and peripapillary retina for differentiating papilledema (all grades and mild) from pseudopapilledema. Cirrus OCT ONH volume scans were acquired from 21 papilledema (15 mild papilledema), 27 pseudopapilledema, and 42 control subjects. Raw scan data were exported, and total retinal thickness within Bruch's membrane opening (BMO) plus RNFLT and total retinal thickness at the following eccentricities were calculated using custom algorithms: BMO to 250, 250 to 500, 500 to 1000, and 1000 to 1500 μm. Minimum rim width was calculated, and BMO height was measured from a 4-mm Bruch's membrane reference plane centered on the BMO. Retinal nerve fiber layer thickness from BMO to 250 μm, minimum rim width, and BMO height had significantly greater areas under the receiver operating characteristic curve than did conventional RNFLT for differentiating mild papilledema from pseudopapilledema (P < .0001) and greater sensitivities at 95% specificity. Using cutoff values at 95% specificity, custom parameters detected 10 mild papilledema patients, and conventional RNFLT detected only 1. Bruch's membrane opening heights above the reference plane were observed in papilledema only, although many papilledema cases had a neutral or negative BMO height. Using OCT volumetric data, additional parameters describing peripapillary tissue thickness, neuroretinal rim thickness, and ONH position can be calculated and provide valuable measures for differentiating mild papilledema from pseudopapilledema.

Menopause exacerbates visual dysfunction in experimental glaucoma

Glaucoma is the leading cause of irreversible blindness worldwide. Recently, estrogen deficiencies caused by early menopause, alterations in estrogen signaling via mutations in estrogen receptors, and polymorphisms along estrogen metabolic pathways have all been linked to an increased risk of developing glaucoma. Here, we examined how menopause and age impact visual function and retinal structure in an experimental model of glaucoma. Young (3–4 months) and aged (9–10 months) female Brown Norway rats were divided into pre- and post-menopausal cohorts by surgically inducing menopause via ovariectomy (OVX). After six weeks, ocular hypertension (OHT) was induced unilaterally for a period of eight weeks. Four cohorts were successfully followed to eight weeks: young sham (n = 8), young OVX (n = 9), aged sham (n = 10), and aged OVX (n = 11) animals. Intraocular pressure (IOP) was monitored weekly in all groups. Prior to inducing OHT (baseline) and at four and eight weeks after inducing OHT, we assessed visual acuity via the optomotor response (OMR) and retinal structure using optical coherence tomography (OCT). OHT decreased the OMR in all cohorts. We found that spatial frequency thresholds decreased by 54% in OVX animals after OHT compared to sham animals after OHT, regardless of age (p < 0.001). We also found thinning of the retinal nerve fiber layer (RNFL) and loss of total retinal thickness after induction of OHT. Aged animals had more thinning of the RNFL and loss of total retinal thickness compared to young animals (p < 0.001). Overall, OHT caused significant changes in visual function and retinal structure. Observing that OVX in young and aged animals further decreased spatial frequency thresholds after OHT suggests that an estrogen deficiency may intensify visual impairment after OHT.

Baseline retinal OCT measurements in normal female beagles: The effects of eccentricity, meridian, and age on retinal layer thickness.

Our aim was to generate baseline optical coherence tomography (OCT) measurements of retinal thickness in female Beagles and to determine how these are affected by meridian, eccentricity, and age. Twenty-three female Beagles, including six puppies (<6months old), six mature (1.8-8.2years old), and 11 elderly dogs (>11years old) were studied. Both retinas of each dog were scanned (in 4 principal meridians) using the Heidelberg Spectralis following ophthalmic examination, refraction, and sedation. In each eye and each meridian, total retinal, outer retinal, and nerve fiber layer (NFL) thickness were measured from the disc rim up to 6mm peripherally. The canine retina is thickest dorsally and thinnest ventrally. Total retinal, outer retinal, and NFL thickness decrease progressively and significantly as a function of eccentricity. The greatest eccentricity-dependent thinning occurs dorsally. This thinning is due mostly to NFL tapering, while the eccentricity-dependent change in outer retinal thickness is more moderate, especially in the lateral meridian, possibly due to the presence of the visual streak. The retina is thickest in puppies, but there were no significant differences between mature and elderly dogs. Our results provide normative values for total, outer, and inner retinal thickness in female dogs and may facilitate OCT use in the diagnosis of canine glaucoma and inherited retinopathies.

MTRR 66 and SHMT1 1420 Variants Are Associated with Optic Disc Edema During 30-d Strict Head-down Tilt Bed Rest and CO2 Exposure (P24-036-19)

ObjectivesSome astronauts returning from missions to the International Space Station (ISS) have developed ophthalmic structural changes, including optic disc edema. Incidence of optic disc edema among astronauts has been linked to one-carbon pathway genetic variants and B-vitamin status. A recent 30-d 6-degree head-down tilt bed rest study in which all subjects were exposed to 0.5% CO2 documented the occurrence of optic disc edema in 5 of 11 subjects. The objective of this study was to determine the effect of one-carbon pathway genetics and B-vitamin status on the incidence of optic disc edema in the bed rest subjects. MethodsThe study was conducted at the: envihab facility at the German Aerospace Center in Cologne, Germany. Subjects (6 M/5F) were healthy volunteers, 33 ± 8 y (mean ± SD), having a mean BMI of 23.4 ± 2.2 kg/m2. After a 14-d ambulatory phase in a standard environment (i.e., not hypercapnic), a blood sample was collected to assess vitamin status and single nucleotide polymorphisms (SNPs) associated with one carbon metabolism. We focused on two SNPs (rs1801394, MTRR 66 and rs1979227, SHMT1 1420) based on our earlier findings in astronauts (Zwart et al., FASEB J, 30:141–8, 2016). The 30-d bed rest began after collection of this sample. Optical coherence tomography images were collected before, during (days 15 and 30), and after (6 and 13 days after reambulation) bed rest, and the change in total retinal thickness (TRT) at various distances from Bruch’s membrane opening (BMO) was evaluated against the number of MTRR A66G G alleles and SHMT1 C1420T C alleles. ResultsThe change in TRT at various distances from the BMO in bed rest subjects exposed to mild hypercapnia and headward fluid shifts was strongly associated with the number of MTRR 66 G and SHMT1 1420 C alleles. ConclusionsThis finding may increase understanding of mechanisms involved in optic disc edema in astronauts and patients on Earth, and hence lead to development of targeted countermeasures. Funding SourcesThis work was funded by the NASA Human Health Countermeasures Element of the NASA Human Research Program.

Macular Carotenoids, Retinal Morphometry, and Cognitive Function in Multiple Sclerosis (OR05-07-19)

ObjectivesIndividuals with multiple sclerosis (MS) often suffer a progressive loss in visual and cognitive function. While the exact reason for the cognitive decline in MS is unknown, generalized neurodegeneration of the central nervous system has been associated with lower carotenoid levels. Carotenoids have antioxidant effects that could support nerve health and be protective against cognitive decline. Carotenoids are also found in high concentration within the center of the retina, or macula. Their role in the brain may be related to their role in the eye and vision health. We investigated the correlation among macular carotenoids, retinal and nerve fiber layer thickness, and cognitive function in patients with MS. MethodsSubjects included persons diagnosed with MS between 45–64 years (N = 29) living in Illinois. Carotenoid accumulation, defined as macular pigment optical density (MPOD), was measured using heterochromatic flicker photometry. Optical coherence tomography (Heidelberg Engineering, Germany) was used to assess total macular volume (TMV), central foveal (CF), and retinal nerve fiber layer thickness (RNFL). Cognitive function was assessed using an Eriksen flanker task for attentional control with event-related brain potentials. ResultsWhile MPOD was not correlated with TMV (Rho = 0.23, P = 0.14), CF (Rho < –0.01, P = 0.50), or RNFL (Rho = 0.19, P = 0.19), MPOD was correlated with faster congruent (Rho = –0.34, P = 0.04) and incongruent reaction time (Rho = –0.33, P = 0.04) and faster congruent (Rho = –0.52, P < 0.01) and incongruent (Rho = –0.37, P = 0.04) P2 latency. RNFL was positively correlated with incongruent accuracy (Rho = 0.41, P = 0.02) and inversely related to incongruent P2 latency (Rho = –0.41, P = 0.05), N2 congruent (Rho = –0.46, P = 0.03), and incongruent (Rho = –0.47, P = 0.03) amplitude. Additionally, RNFL was inversely related to congruent (Rho = –0.51, P = 0.02) and incongruent (Rho = –0.54, P = 0.01) P3 amplitude. Larger TMV was related to faster congruent (Rho = –0.43, P = 0.04) and incongruent P2 latency (Rho = –0.48, P = 0.02). CF was not correlated with any of the cognitive task outcomes. ConclusionsMacular pigmentation and markers of retinal and optic nerve health may positively influence cognitive function in MS. However, MPOD and OCT measures were not correlated, suggesting that macular carotenoids, and retinal and optic nerve thickness may exert independent benefits for cognitive function. Funding SourcesThis work was funded by Pilot Research Grant from the National Multiple Sclerosis Society.

Retinal Oxygen Delivery, Metabolism and Extraction Fraction and Retinal Thickness Immediately Following an Interval of Ophthalmic Vessel Occlusion in Rats

Limited knowledge is currently available about alterations of retinal blood flow (F), oxygen delivery (DO2), oxygen metabolism (MO2), oxygen extraction fraction (OEF), or thickness after the ophthalmic blood vessels have been closed for a substantial interval and then reopened. We ligated the ophthalmic vessels for 120 minutes in one eye of 17 rats, and measured these variables within 20 minutes after release of the ligature in the 10 rats which had immediate reflow. F, DO2 and MO2 were 5.2 ± 3.1 μL/min, 428 ± 271 nL O2/min, and 234 ± 133 nL O2/min, respectively, that is, to 58%, 46% and 60% of values obtained from normal fellow eyes (P < 0.004). OEF was 0.65 ± 0.23, 148% of normal (P = 0.03). Inner and total retinal thicknesses were 195 ± 24 and 293 ± 20 μm, respectively, 117% and 114% of normal, and inversely related to MO2 (P ≤ 0.02). These results reflect how much energy is available to the retina immediately after an interval of nonperfusion for 120 minutes. Thus, they elucidate aspects of the pathophysiology of nonperfusion retinal injury and may improve therapy in patients with retinal artery or ophthalmic artery obstructions.

Retinal layer thickness in preclinical Alzheimer's disease.

PurposeThere is urgent need for non‐invasive diagnostic biomarkers in the preclinical phase of Alzheimer's Disease (AD). Several studies suggest that retinal thickness is reduced in AD. Here, we aim to test the diagnostic value of retinal thickness in preclinical AD, as defined by cognitively normal individuals with amyloid pathology on PET.MethodsOne hundred and sixty five cognitively healthy monozygotic twins aged ≥ 60 were included from the Netherlands Twin Register taking part in the European Medical Information Framework for Alzheimer's Disease PreclinAD study. Participants underwent [18F] flutemetamol PET that was visually rated for presence or absence of cortical amyloid beta (Aβ). Binding potential (BPND) was calculated as continuous measure for Aβ. Spectral Domain OCT was used to asses total and individual inner retinal layer thickness in the macular region (ETDRS circles) as well as peripapillary retinal nerve fibre layer (pRNFL) thickness. Differences between Aβ+ and Aβ− individuals and associations between BPND and retinal thickness were analyzed.ResultsNo differences were found in retinal layer thickness in the macula or pRNFL between Aβ+ and Aβ− individuals. A positive associations between BPND and macular total retinal thickness was observed in the inner ring (p = 0.018), but this was not statistically significant after correction for multiple testing (p = 0.144). Brain/eye parameters had moderate to high intra‐twin correlations (p < 0.001) except visual rating score of Aβ, which did not correlate (r = 0.21, p = 0.068).ConclusionVariation in retinal thickness likely reflects genetic differences between individuals, but cannot discriminate between healthy and preclinical AD cases, making its use as biomarker in these early stages limited.

Low-Luminance Blue Light-Enhanced Phototoxicity in A2E-Laden RPE Cell Cultures and Rats.

N-retinylidene-N-retinylethanolamine (A2E) and other bisretinoids are components of lipofuscin and accumulate in retinal pigment epithelial (RPE) cells—these adducts are recognized in the pathogenesis of retinal degeneration. Further, blue light-emitting diode (LED) light (BLL)-induced retinal toxicity plays an important role in retinal degeneration. Here, we demonstrate that low-luminance BLL enhances phototoxicity in A2E-laden RPE cells and rats. RPE cells were subjected to synthetic A2E, and the effects of BLL on activation of apoptotic biomarkers were examined by measuring the levels of cleaved caspase-3. BLL modulates the protein expression of zonula-occludens 1 (ZO-1) and paracellular permeability in A2E-laden RPE cells. Early inflammatory and angiogenic genes were also screened after short-term BLL exposure. In this study, we developed a rat model for A2E treatment with or without BLL exposure for 21 days. BLL exposure caused fundus damage, decreased total retinal thickness, and caused neuron transduction injury in the retina, which were consistent with the in vitro data. We suggest that the synergistic effects of BLL and A2E accumulation in the retina increase the risk of retinal degeneration. These outcomes help elucidate the associations between BLL/A2E and angiogenic/apoptotic mechanisms, as well as furthering therapeutic strategies.

Headache in Postoperative Isolated Sagittal Synostosis.

This study investigates the relationship between headache and the occurrence of signs associated with intracranial hypertension such as ophthalmic signs, restricted skull growth, and a vertex bulge in children who were operated on for sagittal synostosis. A total of 94 patients (aged 6 to 18 years) with sagittal synostosis were asked to indicate their headache frequency. Based on their age at referral, the patients had undergone either frontobiparietal remodeling or an extended strip craniotomy. Data on funduscopy, optical coherence tomography, occipitofrontal head circumference, and presence of vertex bulge on radiography were collected retrospectively. Univariate analysis showed that extended strip craniotomy, the occurrence of ophthalmic signs, and a smaller occipitofrontal head circumference at last follow-up were related to more frequent headaches (p = 0.01, p = 0.04, and p < 0.01, respectively). On multivariate analysis, only type of surgery and occipitofrontal head circumference at last follow-up remained significant predictors (p = 0.04 and p < 0.01, respectively). Although the reported rate of frequent headaches in this study is within the norm reported for the normal population, this study shows that after correction for sagittal craniosynostosis, frequent headaches are independently related to type of surgery and to occipitofrontal head circumference at last follow-up. Headaches in the sagittal craniosynostosis population may be related to papilledema and/or an increased total retinal thickness. Therefore, the authors recommend that occipitofrontal head circumference be routinely measured and that patients be asked about the occurrence and frequency of headaches during their checkup at the clinic. Therapeutic, III.

Histomorphometric evaluation of the Göttingen minipig eye.

The Göttingen minipig is becoming a popular nonrodent animal model in ocular research; however, there is a paucity of literature regarding normative ocular reference data in this breed. We, therefore, investigated the characteristics of the cornea, retina, and sclera in order to establish baseline histomorphometric data in male and female Göttingen minipigs. This study utilized paraffin-embedded, Davidson's-fixed, control Göttingen minipig eyes (six males and eight females). Hematoxylin and eosin stained slides of the eyes were scanned via an Aperio slide scanner and analyzed using Aperio ImageScope™. Linear measurements were made of the cornea, retina, and sclera. There were no statistically significant differences between males and females in corneal or scleral measurements or total retinal thickness. There were, however, statistically significant differences between the sexes in the thickness of the ventral peripheral ganglion cell layer [13.15µm (±3.65) in males; 10.68µm (±3.37) in females; P=0.03], ventral peripheral inner plexiform layer [23.47µm (±2.85) in males; 21.16µm (±3.62) in females; P=0.03], ventral central outer plexiform layer [7.97µm (±2.43) in males; 6.63µm (±1.73) in females; P=0.02], and ventral peripheral outer plexiform layer [8.79µm (±1.82) in males; 11.23µm (±3.11) in females; P=0.01]. This study provides normative histomorphometric reference data for the Göttingen minipig eye. These data will aid researchers in study design and interpretation of findings in Göttingen minipig ocular studies.

Retinal and choroidal morphological changes in Huntington's disease

Purpose: to investigate the choroidal and retinal morphology in Huntington's disease (HD) using optical coherence tomography (OCT) and to analyze how the parameters studied correlate with the clinical data. Material and methods. The study included two groups of subjects, (1) 44 HD patients, averagely aged 37.6 ± 10.2 yrs, and (2) 31 healthy volunteers, averagely aged 37.3 ± 10.8 yrs. The groups had matching age, sex distribution, intraocular pressure and mean refractive error. In the study group, 21 patients had pre-manifest and 23, manifest HD stage. All patients underwent a thorough neurological and ophthalmic examination which included retinal OCT. The foveal choroidal thickness, retinal thickness in 9 areas of the macular zone, retinal ganglion cells complex (GCC) and peripapillary retinal nerve fiber layer thickness (RNFL) were evaluated in 4 quadrants. CAG repeat expansion size (cytosine-adenine-guanine) in the huntingtin gene, the disease duration and Unified HD Rating Scale motor scores (UHDRS) were evaluated for HD patients. Results. The range of the CAG repeat expansion size in the study group was 37–56 repeats (44.3 ± 3.8), the UHDRS motor score was 36.3 ± 29.7, disease duration was 13.7 ± 7.2 years. OCT revealed a significant decrease in the foveal choroidal thickness, GCC complex thickness, average, temporal, inferior and nasal RNFL thickness and total retinal thickness in the external temporal area in HD patients as compared to the controls. In addition, an inverse correlation between the disease duration, UHDRS Motor Score and a number of OCT parameters was found. Conclusion. The results confirm the promising potential of retinal tomographic parameters as a biomarker for early diagnosis and monitoring of the neurodegenerative process progression. The topography of retinal thickness reduction indicates a specific pattern of retinal neurodegeneration in HD.

The Analysis of Intra-retinal Layers with Automatic Optical Coherence Tomography Segmentation in Healthy Subjects

Aims: To give normative databases of each retinal layers on OCT images in the healthy Caucasian population in Turkey and investigate the relevance of the data with factors such as age, gender, axial length and refraction.&#x0D; Study Design: Prospective, cross sectional, descriptive study.&#x0D; Place and Duration of Study: Department of Ophthalmology, Faculty of Medicine, Kirsehir Ahi Evran University, Kirsehir/TURKEY. Between September 2017 and March 2018.&#x0D; Methodology: 133 participants underwent full ophthalmologic examination and spectral domain OCT imaging (Spectralis, Heidelberg Engineering, Germany). After the automatic segmentation, central 1 mm and 1-3 mm superior, inferior, nasal and temporal thicknesses of 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) analyzed with respect to age, gender, axial length and refraction (spherical equivalent).&#x0D; Results: Central 1 mm INL, ONL, ORL, IRL and TRT and four quadrants of pericentral 1-3 mm thicknesses of RPE had positive correlation with the age. All the sections of total retina, RNFL, GCL, IPL, INL, ONL and IRL thicknesses were significantly thicker in males compared to females. The thicknesses of all RNFL sections and central 1 mm circle thicknesses of TRT, IPL, INL, OPL, RPE and IRL had positive correlation with the axial length.&#x0D; Conclusion: A normative database for thicknesses of intra-retinal layers in Turkish population was presented in the study and significant impacts of the age, gender and axial length were presented.

Posterior pole asymmetry analysis and retinal nerve fibre layer thickness measurements in primary angle-closure suspect patients

PurposeTo measure peripapillary retinal nerve fiber layer (RNFL) thickness and posterior pole retinal thickness in primary angle-closure suspects (PACS) by Spectral domain optical coherence tomography (SD-OCT) and to be compared with normal subjects.MethodsThirty five primary angle-closure suspect patients and thirty normal subjects were enrolled in this study. Peripapillary RNFL and posterior pole retinal thickness by posterior pole asymmetry analysis (PPAA) in SD-OCT were measured.ResultsNo significant difference was found in both groups on age, sex distribution, refractive error, intraocular pressure (IOP) and axial length. The PACS group exhibited significantly thinner macular retinal thickness and larger asymmetry on posterior pole region compared with the control group. Yet no significant difference of peripapillary RNFL parameters was found between PACS group and normal control group. A negative correlation was observed between the total retinal thickness on posterior pole region and age when all the PACS participants were analyzed.ConclusionsPosterior pole retinal thickness measurements obtained by Heidelberg Spectralis SD-OCT using PPAA showed significant thinner change in PACS group than healthy controls. Only age seemed to be an indicator in the occurrence of glaucomatous damage in PACS patients.

Analysis of Changes in Retinal Photoreceptors Using Optical Coherence Tomography in a Feline Model of Iodoacetic Acid-induced Retinal Degeneration.

PurposeWe investigated structural changes in the retina by using optical coherence tomography (OCT) in a feline model of retinal degeneration using iodoacetic acid (IAA).MethodsWe examined 22 eyes of 11 felines over 2 years of age. The felines had fasted for 12 hours and were intravenously injected with IAA 20 mg/kg of body weight. OCT (Spectralis OCT) was performed at the point where the ends of the retinal vessels collected in the lateral direction from the optic nerve head and area centralis. Similarly, OCT was performed four times at 1-week intervals following injections, at which point the felines were sacrificed and histologic examinations were performed. Using OCT, the thickness of each layer of the retina was measured.ResultsThe average body weight of the three male and eight female felines investigated in this study was 1.61 ± 0.19 kg. The mean total retinal thickness of the felines before injection was 221.32 ± 9.82 µm, with a significant decrease in the retinal thickness at 2, 3, and 4 weeks following injections of 186.41 ± 35.42, 174.56 ± 31.94, and 175.35 ± 33.84 µm, respectively (p = 0.028, 0.027, and 0.027, respectively). The thickness of the outer nuclear layer was 57.49 ± 8.03 µm before injection and 29.26 ± 17.87, 25.62 ± 13.88, and 31.60 ± 18.38 µm at 2, 3, and 4 weeks, respectively, after injection (p = 0.028, 0.028, 0.046, respectively).ConclusionsIn a feline model of retinal degeneration using IAA, the total retinal thickness and the thickness of the outer nuclear layer were shown to decrease significantly on OCT.

Scattering-Angle-Resolved Optical Coherence Tomography of a Hypoxic Mouse Retina Model.

Several studies have noted a correlation between retinal degeneration and traumatic encephalopathy (TE) making the retina a leading candidate for detection and assessment. Scattering-angle-resolved optical coherence tomography (SAR-OCT) is a candidate imaging modality to detect sub-resolution changes in retinal microstructure. SAR-OCT images of murine retinas that experience a hypoxic insult—euthanasia by isoflurane overdose—are presented. A total of 4 SAR-OCT measurement parameters are reported in 6 longitudinal experiments: blood flow volume fraction, total retinal thickness, reflectance index, and scattering angle. As each mouse expires, blood flow volume fraction decreases, total retinal thickness increases, reflectance index decreases, and scattering angle diversity increases. Contribution of the retinal vasculature to scattering angle diversity is discussed. Results of this study suggest the utility of SAR-OCT to measure TE using scattering angle diversity contrast in the retina.

CHOROIDAL THICKNESS CHANGES IN ACUTE ZONAL OCCULT OUTER RETINOPATHY.

To investigate the longitudinal morphologic choroidal changes in eyes with acute zonal occult outer retinopathy. In this retrospective observational case series, we studied 10 patients (11 eyes) with unilateral acute zonal occult outer retinopathy at the first visit who were followed more than 12 months by enhanced depth optical coherence tomography. The retinal and choroidal thicknesses (CTs) were measured at six sites in the macula. The integrity of the ellipsoid zone was lost 1,500 μm and 3,000 μm nasally in all 11 eyes at the first visit. Compared with the unaffected fellow eyes, the mean total retinal thickness at the first visit was significantly (P = 0.03) thinner 3,000 μm nasal to the fovea in the affected eyes. The mean CTs in the affected eyes did not differ from that in the unaffected eyes at any evaluation; the mean subfoveal CT in the affected eyes gradually decreased during the follow-up period. Compared with the first visit, the mean subfoveal CT decreased significantly (P = 0.011) at the foveal center and nasal, superior, and temporal to the fovea 12 months after disease onset. The subfoveal CT in eyes with acute zonal occult outer retinopathy can decrease during follow-up.

Analyzing the impact of glaucoma on the macular architecture using spectral-domain optical coherence tomography.

PurposeUsing spectral domain optical coherence tomography (SD-OCT) the retina can be segmented automatically to visualize all retinal layers. In glaucoma chronically elevated intraocular pressure leads to a decline of retinal ganglion cells (RGC) which changes retinal architecture. The goal of these analyses was to gain insight into the changes induced by glaucoma within all macular layers using SD-OCT within a closely circumscribed glaucoma cohort.Materials and methodsSD-OCT measurements with automated retinal layer segmentation were performed in both eyes of primary open-angle glaucoma patients with a defined monocular absolute visual field scotoma in the central 10° of the visual field and in an age-matched healthy control group. Thickness of single retinal layers and entire retina were compared with special attention to the localization of the visual field scotoma in the glaucomatous eyes.Results30 eyes of 15 glaucoma patients and 15 eyes of 15 healthy controls were included in this study. Statistical significant thickness differences were detected in the control group between superior and inferior retina for the retinal nerve fiber layer (RNFL), the outer plexiform layer (OPL) and the outer nuclear layer (ONL). In the glaucoma group thickness differences between worse and less affected eyes in the RNFL, the ganglion cell layer (GCL) and the inner plexiform layers (INL) were found. Comparison between healthy and diseased eyes revealed significant thickness differences in the RNFL, GCL, IPL and total retinal thickness but not the outer retinal layers.ConclusionComparison between SD-OCT measurements of the macula between healthy and glaucomatous eyes in a closely circumscribed disease stage showed a pronounced disease impact on the inner but not the outer retina. These results provide evidence that GCL and IPL thickness seem to be good measures to discriminate between affected and unaffected eyes in testing for glaucoma.

The thickness and volume of the choroid, outer retinal layers and retinal pigment epithelium layer changes in patients with diabetic retinopathy.

To evaluate the thickness and volume changes of the choroidal, outer retinal layers (ORL) and retinal pigment epithelium (RPE) in patients with diabetic retinopathy (DR) using optical coherence tomography (OCT) and correlate them with visual acuity. We carried out a retrospective observational case series. Consecutive DR patients were recruited for color fundus photography and OCT assessment. The RPE, ORL and choroidal thickness were measured. The correlation with the best-corrected visual acuity (BCVA) was also investigated. The study included 128 eyes, comprising 45 eyes of 25 diabetic macular edema (DME) patients, 34 eyes of 20 DR without DME (non-DME) patients, and 49 eyes of 25 age-matched normal individuals. The choroidal thickness in DR patients were decreased statistically significantly compared with the control group (P<0.05). The mean macular ORL thickness in DME (73.02±15.34 µm) and non-DME groups (76.35±7.32 µm) were decreased statistically significantly compared with the control group (80.20±5.85 µm; P=0.006, P=0.013, respectively). In both the non-DME and DME groups, the RPE thickness were decreased compared with the control group (P<0.05), except in the macular and central ring. The BCVA were significant interactions with the total inner retinal volume and macular RPE thickness in the DME group (r=0.115, P<0.001, r=-0.013, P=0.017, respectively). The choroid, ORL and RPE thickness are significantly decreased in DR patients compared with controls in different segments.

The Effect of Zinc-Deficient Pregnant Albino Rats on the Retinal Development of their Embryos and Offspring: Light Microscopic and Immunohistochemical Study

AbstractBackground: Zinc is involved in many biochemical func-tions. Over 300 enzymes require zinc for their activation and nearly 2000 transcription factors require zinc for gene expres-sion. Zinc is also an effective antioxidant and anti-inflammatory agent. Nutritional deficiency of zinc may affect nearly 2 billion subjects in the developing world.Aim of Study: Because of the prevalence of malnutrition throughout the world this study was carried out to detect the possible effects of zinc-deficient pregnant albino rats on the retinal development of their embryos and offspring.Material and Methods: Female rats after mating were randomly divided into 2 equal groups: One control group received single intraperitoneal injection of distilled water on day 9 of gestation and one experimental group received intraperitoneal injections of 1.10 phenanthroline (zinc chelator purchased from Sigma Company), in a single dose of 30 mg/kg on day 9 of gestation. From the embryos and offspring of both control and treated mothers (at the following prenatal gestational days: 13, 15, 17, 19 and the following postnatal days: (newborn, 7 days, 15 days and 21 days), retinal specimens were processed for Haematoxylin & Eosin staining technique and immunohistochemical study using caspase-3 antibody was used to detect apoptosis in the postnatal age groups.Results: The light microscopic study of the 13 days zinc deficient embryo retina showed apparent shrinkage of the lens vesicle and the optic cup was well formed but it appeared to be shrunken. The retinal pigment epithelium (RPE) of 15th, 17th and 19th day old zinc-deficient embryos consistently contained apoptotic cells with vacuolated cytoplasm and rarified nuclei. The neuroblastic layer showed apparent de-crease in thickness and less mitotic features. The ganglion cell layer revealed numerous deeply stained pyknotic nuclei in the 19th gestational day. Retinae of the newborn, 7 days, 15 days, 21 days-old zinc deficient albino rats showed that the (RPE) contained some vacuolated cells with pyknotic nuclei. The organization of the retina was altered in zinc deficient rats. In addition, apparent reduction in the total retinal thickness and degenerative changes in some layers were observed. By the immunohistochemical study, there was intense positive caspase-3 reaction in all layers of the treated rat retina.Conclusion: This study revealed that zinc has a role in the developing rat retina and its deficiency causes cytoarchi-tectural and maturational changes in the retina of the albino rats. These histological changes may impair the visual functions of the retina; so it is recommended that further investigations should be carried out to determine the relevancy of deprivation of zinc as an etiologic factor in the development of retinal degeneration.

Longitudinal Assessment of Retinal Structure in Achromatopsia Patients With Long-Term Follow-up.

PurposeTo longitudinally characterize structural retinal changes in achromatopsia (ACHM) over extended follow-up.MethodsFifty molecularly confirmed ACHM subjects underwent serial spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) imaging. Foveal structure on SD-OCT was graded and compared for evidence of progression, and foveal total retinal thickness (FTRT) and outer nuclear layer (ONL) thickness were serially measured. FAF patterns were characterized and compared over time.ResultsMean SD-OCT follow-up was 61.6 months (age range at baseline, 6–52 years). Forty-five of the subjects had serial FAF (mean follow-up: 48.5 months). Only 6 (12%) of the subjects demonstrated qualitative change on serial foveal SD-OCT scans. Among the entire cohort, there was no statistically significant change over time in FTRT (P = 0.2459) or hyporeflective zone (HRZ) diameter (P = 0.3737). There was a small—but statistically significant—increase in ONL thickness (P = 0.0084). Three different FAF patterns were observed: centrally increased FAF (13/45), normal FAF (14/45), and well-demarcated reduced FAF (18/45), with the latter group displaying a small gradual increase in the area of reduced FAF of 0.055 mm2 over 43.4 months (P = 0.0011).ConclusionsThis longitudinal study of retinal structure in ACHM represents the largest cohort and longest follow-up period to date. Our findings support the presiding notion that ACHM is essentially a stationary condition regarding retinal structure, and any change over time is likely to be small, slow, and variable across patients. This may potentially afford a wider window for therapeutic intervention.