Normative data on the foveal avascular zone in a young healthy Irish population using optical coherence tomography angiography

Purpose To establish normative data on the size, shape and vascular profile of the foveal avascular zone (FAZ) in a young, healthy, Irish population, using the Cirrus 5000 HD-OCT. Certain diseases may alter FAZ appearance. Normative databases provide normal baseline values for comparison, thus improving diagnostic ability. Methods One hundred and fifty-four subjects aged 18–35 years old were recruited. Superficial FAZ area, diameter, circularity, ganglion cell layer, central macular thickness (CMT), vascular perfusion and density were measured using the Cirrus 5000. Axial length was measured with the IOL Master and blood pressure was measured using the Omron sphygmomanometer. Results Mean FAZ area was 0.22 ± 0.07 mm2, mean CMT was 263.08 ± 18.73μm. Both were larger in females than males (p = 0.022, p = 0.000). Mean vessel density and perfusion central were 14.11 ± 2.77 mm/mm2 and 24.70 ± 4.96% respectively. Both were lower in females (p = 0.010, p = 0.019). Vessel density and perfusion inner correlated positively with minimum ganglion cell layer plus inner plexiform layer (GCL + IPL) thickness (p = 0.001, p = 0.019). CMT correlated positively with vessel density and perfusion central (p = 0.000 for both) and negatively with FAZ area (p = 0.000). Conclusions This study provides normative data for FAZ appearance and vascularity for the first time in a young, healthy, Irish population, using the Cirrus 5000 HD-OCT. Establishing machine and population specific normative data, particularly in relation to vessel density and perfusion is paramount to the early identification of ocular disease using Optical Coherence Tomography Angiography.

Relationship between the sFlt-1/PlGF ratio and the optical coherence tomographic features of chorioretina in patients with preeclampsia

This study aimed to evaluate the correlation between ophthalmologic factors and the serologic indicator soluble fms-like tyrosine kinase 1 (sFlt-1): placental growth factor (PlGF) ratio in patients with preeclampsia using optical coherence tomography (OCT) and OCT angiography (OCT-A). A total of 52 pregnant patients (104 eyes) diagnosed with preeclampsia were recruited during their hospital stay. The associations between the sFlt-1/PlGF ratio and chorioretinal measurements, including the choroidal thickness (CT), foveal avascular zone, vascular density, and ganglion cell layer+ were evaluated. Central and nasal subfield CT of the left eye (p = 0.039; p = 0.010) and nasal subfield CT of the right eye (p = 0.042) were lower in the high sFlt-1/PlGF ratio group (≥38). Pearson’s correlation test showed a negative correlation between the sFlt-1/PlGF ratio and central subfield CT; however, this was not statistically significant (p = 0.648). Linear regression analysis revealed a significant association between the sFlt-1/PlGF ratio and central subfield CT (β coefficient, -6.66; p = 0.01) and between sFlt-1 and central subfield CT (β coefficient, -5.65; p = 0.00). Thus, an increase in the sFlt-1/PlGF ratio resulted in a decrease in central subfield CT.

Investigation of the pathophysiology of the retina and choroid in Parkinson's disease by optical coherence tomography

Purpose The pathology of Parkinson's disease (PD) is suspected to affect the retina and choroid. We investigated changes in the retina and choroid of patients with PD using optical coherence tomography. Methods We examined 14 patients with PD and 22 patients without PD. Patients without PD had no ophthalmic disease other than cataracts. In addition, it was also confirmed that there was no neurodegenerative disease. The retinal nerve fiber layer, ganglion cell layer + inner plexiform layer, and choroidal thickness were compared between both groups. Additionally, the choroidal image was divided into the choroid area, luminal area, and interstitial area using the binarization method, and the area of each region and the percentage of luminal area in the choroid area were analyzed. Results Patients with PD had a significantly thinner ganglion cell layer + inner plexiform layer compared to those without PD. The choroid area, luminal area, and interstitial area were significantly decreased in patients with PD compared to those without PD. Seven patients with PD who were successfully followed up showed decreased retinal nerve fiber layer and interstitial area after 3 years. Conclusion Autonomic nervous disorders and neurodegeneration in PD can cause thinning of the retina and choroid, as well as a reduction in the choroid area.

Structural and (Pseudo-)Enzymatic Properties of Neuroglobin: Its Possible Role in Neuroprotection

Neuroglobin (Ngb), the third member of the globin family, was discovered in human and murine brains in 2000. This monomeric globin is structurally similar to myoglobin (Mb) and hemoglobin (Hb) α and β subunits, but it hosts a bis-histidyl six-coordinated heme-Fe atom. Therefore, the heme-based reactivity of Ngb is modulated by the dissociation of the distal HisE7-heme-Fe bond, which reflects in turn the redox state of the cell. The high Ngb levels (~100–200 μM) present in the retinal ganglion cell layer and in the optic nerve facilitate the O2 buffer and delivery. In contrast, the very low levels of Ngb (~1 μM) in most tissues and organs support (pseudo-)enzymatic properties including NO/O2 metabolism, peroxynitrite and free radical scavenging, nitrite, hydroxylamine, hydrogen sulfide reduction, and the nitration of aromatic compounds. Here, structural and (pseudo-)enzymatic properties of Ngb, which are at the root of tissue and organ protection, are reviewed, envisaging a possible role in the protection from neuronal degeneration of the retina and the optic nerve.

Localisation of cryptochrome 2 in the avian retina

Cryptochromes are photolyase-related blue-light receptors acting as core components of the mammalian circadian clock in the cell nuclei. One or more members of the cryptochrome protein family are also assumed to play a role in avian magnetoreception, but the primary sensory molecule in the retina of migratory birds that mediates light-dependent magnetic compass orientation has still not been identified. The mRNA of cryptochrome 2 (Cry2) has been reported to be located in the cell nuclei of the retina, but Cry2 localisation has not yet been demonstrated at the protein level. Here, we provide evidence that Cry2 protein is located in the photoreceptor inner segments, the outer nuclear layer, the inner nuclear layer and the ganglion cell layer in the retina of night-migratory European robins, homing pigeons and domestic chickens. At the subcellular level, we find Cry2 both in the cytoplasm and the nucleus of cells residing in these layers. This broad nucleic expression rather points to a role for avian Cry2 in the circadian clock and is consistent with a function as a transcription factor, analogous to mammalian Cry2, and speaks against an involvement in magnetoreception.

Expression of Slit2 and Robo Receptors in a Sprague-Dawley Rat Glaucoma Model

Background: This study investigated immunoreactive changes in Slit2 and Robo receptors in the retinal ganglion cell layer of a rodent model of acute glaucoma. Methods: Glaucoma model using Sprague-Dawley rats was made via weekly intracameral injections of hyaluronic acid. Intraocular pressure (IOP) was measured twice weekly for 4 weeks using a rebound tonometer in an experimental group of 10 rats and a control group of five rats for 4 weeks. The trimmed retinas were processed for anti-glial fibrillary acidic protein (GFAP), anti-Slit2 and anti-Robo1, anti-Robo2, anti-Robo3 and anti-Robo4 immunochemical analysis. Result: The IOPs in the experimental group were approximately four times higher than IOPs in the control group. The GFAP, Slit2 and Robo4 immunoreactivity in the experimental group was higher than the corresponding values in the control group. Our results indicate that Slit2 and Robo4 potentially contribute to the progression of high tension glaucoma, especially in inducing ischemic injury.

Predicting Retinal Sensitivity Using Optical Coherence Tomography Parameters in Central Serous Chorioretinopathy

Purpose To predict the change of retinal sensitivity using optical coherence tomography (OCT) parameters in eyes with central serous chorioretinopathy (CSC). Methods Twenty-three eyes of 23 patients with CSC were enrolled. Retinal sensitivity was measured twice with a microperimetry in all examined eyes. OCT measurement was simultaneously conducted. The relationship between retinal sensitivities and the thicknesses of i) retinal nerve fiver layer + ganglion cell layer (RNFL+GCL), ii) inner nuclear layer (INL) iii) outer nuclear layer (ONL) and iV) serous retinal detachment height (SRDH) were investigated in a point-wise manner. We also investigated the association between the change of retinal sensitivity and OCT parameters at baseline. Results The mean age of participants was 49.8 ± 10.7 years. The mean SRDH was significantly lower (p<0.001) and the mean retinal sensitivity (p<0.001) was significantly higher in the 2nd examination compared to the 1st measurements, however LogMAR visual acuity (VA) was not significantly different between the two measurements (p=0.063). LogMAR VA was associated with retinal sensitivity both in the 1st and 2nd measurements (p<0.001). The retinal sensitivity in the 2nd examination was significantly correlated with retinal sensitivity, RNFL+GCL, INL, ONL, SRDH in the 1st examination and the improvement of SRDH. Conclusions Retinal sensitivity was associated with retinal structure in eyes with CSC; these parameters were useful to predict the change of visual function before the treatment.

Silent Information Regulator T1 in Aqueous Humor of Patients with Age-Related Macular Degeneration

Purpose: The purpose of this study is to compare the aqueous humor level of Silent Information Regulator T1 (SIRT1) between patients with Age-related Macular Degeneration (AMD) and cataract patients. Materials and Methods: Aqueous humor level of SIRT1 was measured by enzyme-linked immunosorbent assay in 13 patients with wet-type AMD (n=13, AMD group) and 13 patients with cataracts (cataract group). In addition, the thickness of each retinal layer was determined by optical coherence tomography. Results: The aqueous humor level of SIRT1 was significantly lower in the AMD group than in the cataract group (p=0.007). In the AMD group, the SIRT1 level was positively correlated with the thickness of the retinal ganglion cell layer (r=0.31) and the inner nuclear layer (r=0.76). Conclusion: The aqueous level of SIRT1 decreased as the ganglion cell layer and inner nuclear layer became thinner, suggesting that reduction of SIRT1 activity might be involved in the pathogenesis of this disease.