Disc Rim Area Research Articles

Optic Nerve Head and Retinal Nerve Fiber Layer Analysis in Emmetropic Malay Children.

The study aims to investigate the normal reference values for optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters in emmetropic Malay children, utilizing measurements obtained through Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA). A cross-sectional study was conducted on 95 Malay children, aged between seven and 17 years, with no ocular abnormalities. It was held at Hospital Universiti Sains Malaysia, Malaysia, from January 2014 to December 2015. All children underwent a full ocular examination, including refraction and calculation of axial length. ONH and retinal nerve fiber layer thickness (RNFLT) parameters were measured using the Cirrus SD-OCT machine. One eye of each subject was selected randomly for study. The associations between the parameters and the effect of age, gender,axial length, and spherical equivalent (SE) on the measurements were statistically validated. Ninety-five children were involved in the study, with 65 females (68.4%) and 30 males (31.6%). The mean age was 10.6 (2.82) years, the mean intraocular pressure (IOP) was 14.8 (2.81) mmHg, the mean SE-refraction was 0.12 (0.28) diopters, and the mean axial length was 23.03 (0.76) mm. The mean disc area, rim area, and cup volume were 2.32 (0.40) mm2, 1.53 (0.33) mm2, and 0.204 (0.16) mm3, respectively. The average cup-to-disc ratio (SD) (CDR) and the vertical CDR were 0.55 (0.13) and 0.50(0.14). Mean (SD) RNFLT was 102.08 (11.08) μm for all patients. There was a strong positive correlation between the average, superior, and inferior RNFLT with the optical disc area. The rim area and the average, superior, inferior, and nasal RNFLT alsoshowed a significant correlation. The inferiorRNFLT was negatively correlated with the average CDR. There was also a major influence of gender on the disc area. There were no major age, axial length, and SE influences on the measurements. This study provided normative information for ONH and RNFLT parameters in emmetropic Malay children. It was observed that emmetropic Malay males exhibited a significantly larger optical disc area. The increase in RNFLT is correlated with a significant increase in disc and rim areas.

Parapapillary choroidal microvasculature dropout in eyes with primary open-angle glaucoma

The purpose of this study was to evaluate how various parameters are related to microvasculature dropout (MvD) area measured using optical coherence tomography angiography (OCTA). We measured the area of MvD in 55 patients with primary open-angle glaucoma (POAG). Using OCTA, MvD area and peripapillary choroidal atrophy (PPA) area were assessed in a 4.5 mm × 4.5 mm region. The following were examined: circumpapillary nerve fiber layer (cpRNFL) thickness, optic disc area, optic disc cupping area, optic disc rim area, Humphrey Field Analyzer (HFA) 24/10–2 mean deviation (MD), and pattern standard deviation (PSD). The relationship between MvD area and each parameter was evaluated using Spearman’s rank correlation coefficient analysis. Mean MvD area and PPA area were 0.18 ± 0.17 mm2 and 1.13 ± 0.72 mm2, respectively. MvD area was significantly correlated with optic disc rim area (p = 0.0017), cpRNFL (p = 0.0027), HFA 24/10–2 MD, and PSD (p < 0.001). In eyes with POAG, MvD area indicates the severity of glaucoma, which might be associated with structural changes in the peripapillary vasculature around the optic disc.

Influencia de la longitud axial ocular en el grosor de la capa de fibras nerviosas peripapilar medido con tomografía de coherencia óptica

BackgroundOptical coherence tomography (OCT) allows the measurement of the peripapillary optic nerve fiber layer (RNFL) thickness. The effect of ocular axial length (AL) on RNFL thickness measurement may be relevant in the interpretation of OCT results in diagnosing optic nerve diseases. PurposesTo assess the influence of ocular AL on RNFL thickness and on optic disc topographic parameters (optic disc area, rim area and cup volume) measured by OCT, in healthy individuals. MethodA sample of 109 healthy eyes classified into three groups according to AL (A: AL <22mm; B: AL 22–24.5mm; C: AL >24.5mm) was studied. RNFL thickness and optic disc topographic parameters were measured using Swept-Source OCT Triton (Topcon Corporation, Tokyo, Japan) and were compared between groups using a variance analysis. Correlation between the AL and the study variables was performed using a Pearson's correlation coefficient test. ResultsThe RNFL thickness was lower in eyes with higher AL in the superior (r=−0.41; p<0.001), inferior (r=0.58; p<0.001) and nasal (r=−0.43; p<0.001) quadrants, in the mean value of the RNFL (r=−0.49; p<0.001), optic disc area (r=−0.40; p<0.001) and rim area (r=−0.25; p=0.01). ConclusionAL is negatively correlated with RNFL thickness and optic disc topographic parameters measured by Swept-Source OCT Triton (Topcon).

Ocular axial length influence on peripapillary retinal nerve fiber layer thickness measurement with optical coherence tomography

BackgroundOptical coherence tomography (OCT) allows the measurement of the peripapillary optic nerve fiber layer (RNFL) thickness. The effect of ocular axial length (AL) on RNFL thickness measurement may be relevant in the interpretation of OCT results in diagnosing optic nerve diseases. PurposeTo assess the influence of ocular AL on RNFL thickness and on optic disc topographic parameters (optic disc area, rim area and cup volume) measured by OCT, in healthy individuals. MethodsA sample of 109 healthy eyes classified into 3 groups according to AL (A: AL<22mm; B: AL 22−24.5mm; C: AL>24.5mm) was studied. RNFL thickness and optic disc topographic parameters were measured using Swept-Source OCT Triton (Topcon) and were compared between groups using a variance analysis. Correlation between the AL and the study variables was performed using a Pearson's correlation coefficient test. ResultsThe RNFL thickness was lower in eyes with higher AL in the superior (r=−0.41; p<0.001), inferior (r=0.58; p<0.001) and nasal (r=−0.43; p<0.001) quadrants, in the mean value of the RNFL (r=−0.49; p<0.001), optic disc area (r=−0.40; p<0.001) and rim area (r=−0.25; p=0.01). ConclusionsAL is negatively correlated with RNFL thickness and optic disc topographic parameters measured by Swept-Source OCT Triton (Topcon).

Comparison of Diagnostic Ability Between Wide-Field Swept-Source Optical Coherence Tomography Imaging Maps and Heidelberg Retina Tomograph 3 Optic Nerve Head Assessment to Discriminate Glaucomatous and Non-glaucomatous Eyes.

BackgroundIn this study, we aimed to determine the diagnostic performance of optic nerve head (ONH), macular, and circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurements of wide-field maps (12 × 9 mm) using swept-source optical coherence tomography (SS-OCT) compared to measurements of the ONH and RNFL parameters measured by Heidelberg Retina Tomograph (HRT3).MethodologyThis case-control study included 39 eyes of 39 glaucoma patients and 36 eyes of 36 normal subjects (control group). All participants underwent standard automated perimetry (SAP) as well as structural measurements by SS-OCT (DRI-OCT, Triton; Topcon Inc., Tokyo, Japan) and HRT3 (Heidelberg Engineering, Heidelberg, Germany). The abilities of the continuous parameters to discriminate between glaucoma and control groups were assessed using areas under the receiver operating characteristic curves (AUCs). To assess the glaucoma diagnostic abilities of each of the categorical variables, sensitivity, specificity, positive predictive value, and negative predictive value were tested.ResultsThe highest sensitivities were achieved by the DRI-OCT categorical parameters of Superpixel-200 map and cpRNFL (12 sectors) thickness analysis. The best performing HRT3 continuous parameter was rim volume (AUC = 0.829, 95% confidence interval (CI) = 0.735-0.922), and the best continuous parameter for DRI-OCT wide-field was vertical cdr (AUC = 0.883, 95% CI = 0.805-0.951), followed by total cpRNFL thickness (AUC = 0.862, 95% CI = 0.774-0.951). AUCs for disc area, rim area, linear cdr, and RNFL thickness were not significantly different between the two technologies. Using either the most or the least specific criteria, SuperPixel-200 map always showed the highest sensitivity among the categorical parameters of both technologies (82.1% and 89.7%, respectively). The highest sensitivity among HRT3 classification parameters was shown by MRA and GPS classification algorithms.ConclusionsBoth wide-field DRI-OCT maps and HRT3 showed good diagnostic performance in discriminating glaucoma. Although DRI-OCT thickness values and normative diagnostic classification showed the best performance, more studies are required to determine the clinical role of wide-field DRI-OCT scan in glaucoma diagnosis.

Platelet Parameters and Their Relationships With the Thickness of the Retinal Nerve Fiber Layer and Ganglion Cell Complex in Primary Open-Angle Glaucoma.

ObjectiveGlaucoma is a neurodegenerative disease of the visual system. Platelet parameters are correlated with visual field mean deviation (MD) in glaucoma, but there is a lack of relative data on their relationship with structural changes in the retina. This study aimed to explore the relationship between platelet parameters and retinal nerve fiber layer (RNEL), ganglion cell complex (GCC) thickness, and cup/disk area ratio, evaluated by optical coherence tomography (OCT) in primary open-angle glaucoma (POAG).MethodsA total of 118 consecutive patients with POAG and 120 age- and sex-matched control subjects were included in this retrospective study. Demographic data, platelet parameters in blood tests, visual field, and OCT results were evaluated. The RNFL was divided into the temporal, superior, nasal, and inferior quadrants. Based on the visual field MD, the patients were stratified into mild (MD ≤ 6.0 dB), moderate (6 dB < MD ≤ 12 dB), and severe (MD > 12.0 dB) subgroups.ResultsPatients with POAG had significantly lower platelet (PLT) levels and significantly higher platelet distribution width (PDW) and mean platelet volume (MPV) levels than controls. As the visual field MD increased, structural evaluation by OCT identified loss of disk rim area, average GCC thickness, and average RNFL thickness (all P < 0.001), as well as increased PDW (P < 0.001) and MPV (P = 0.004) levels in patients with POAG. The Spearman's rank correlation analysis showed that PDW levels were significantly correlated with OCT parameters such as RNFL thickness (r = −0.370, P < 0.001), GCC thickness (r = −0.294, P = 0.001), and cup/disk area ratio (r = 0.322, P < 0.001), as well as visual field MD (r = 0.607, P < 0.001) and mean sensitivity (MS) (r = −0.570, P < 0.001). Significantly correlations were also found between MPV and RNFL thickness (r = −0.321, P < 0.001), GCC thickness (r = −0.194, P = 0.041), and cup/disk area ratio (r = 0.237, P = 0.010). All the quadrants showed similar negative correlations between PDW, MPV, and RNFL thickness. The multiple linear regression analyses showed significant association between PDW and RNFL thickness (β = −0.331, P < 0.001), PDW and GCC thickness (β = −0.288, P = 0.002), MPV and RNFL thickness (β = −0.313, P = 0.001), and MPV and GCC thickness (β = −0.188, P = 0.048).ConclusionThis study found significantly negative association between PDW, MPV levels and RNFL, GCC thickness, as well as positive association between PDW, MPV levels, and cup/disk area ratio in patients with POAG, suggesting that platelet activation may contribute to glaucomatous optic neuropathy.

Macula and optic disk features in methamphetamine and crystal methamphetamine addicts using optical coherence tomography.

Methamphetamine and crystal methamphetamine abusers were compared with healthy subjects using optical coherence tomography to assess their retinal nerve fiber layer, macula, and optic disk characteristics. Forty-one methamphetamine and crystal methamphetamine abusers and 42 healthy subjects (mean ± SD of age: 35.82 ± 8.6 and 37.76 ± 9.1years, respectively) were incorporated in this cross-sectional study. The drug abusers had a history of at least five years of substance use through smoking. Fourier-domain optical coherence tomography was used to image and assess the characteristics of retinal nerve fiber layer, macular thickness, and optic disk in the study groups. The retinal nerve fiber layer thickness was significantly lower in the superior and temporal retinal quadrants of drug abusers than healthy subjects (P = 0.008 andP = 0.028, respectively). This study did not find a significant difference between drug abusers and healthy controls regarding optic to disk ratio, rim area, and disk area (P > 0.05). The comparison between the study groups showed that the reductions in perifovea and the superior quadrant of parafoveal thickness were statistically significant (P < 0.001 andP = 0.029, respectively). Fourier-domain optical coherence tomography measurements showed that the retinal nerve fiber layer and macular thickness were different between methamphetamine and crystal methamphetamine abusers and healthy subjects, which should be considered in clinical practice. It seems that these drug abuses can cause alterations in retinal morphology.

Do Gender, Age, Body Mass and Height Influence Eye Biometrical Properties in Young Adults? A Pilot Study.

Background: Do gender, age, body mass and height influence eye biometrical properties in young adults? Methods: A total of 155 eyes (92 female, 63 male) of healthy subjects between the ages of 18 and 39 years were included in the study. The subjects’ gender and age were recorded, and their body mass, height and biometrical properties of the eyes were measured. Results: The male subjects had significantly thicker and flatter corneas and lower minimal rim-to-disk ratios than the female subjects did. In both genders, age showed strong, negative correlations with anterior chamber depth and pupil diameter and a positive correlation with lens thickness. We also found significant, negative correlations between body height and mass with keratometry measurements, negative correlations between body height and optic disk rim area and rim volume, and positive correlations between body mass and axial length in both genders. Conclusions: Biometric eye parameters differ among people. In addition to age and gender, which are usually taken into consideration when interpreting ocular biometry findings, we strongly suggest that body height and mass should be also routinely considered when interpreting eye biometry data, as these factors have an impact on ocular biometry.

Evaluation of migraine patients with optical coherence tomography angiography.

To compare optical coherence tomography angiography (OCTA) findings in cases with migraine and healthy controls. Thirty-eight eyes of 19 patients with migraine with aura and 38 eyes of 19 healthy subjects were enrolled in this prospective and comparative study. All patients and healthy controls were evaluated with OCTA (Triton, Topcon®, Tokyo, Japan). Central macular thickness (CMT), optic disc parameters (such as retinal nerve fibre layer [RNFL] thickness and rim and disc areas), foveal avascular zone (FAZ) and parafoveal superficial vessel density (VD) measurements were analysed. The optic disc rim area was significantly larger in the migraine group compared to the control group (p = 0.009). In OCTA measurements, the FAZ area was significantly larger in migraine patients (p = 0.001). The parafoveal superficial VD measurements were found to be lower in the migraine patients in all quadrants, but not statistically significant. Weak negative correlations were found between superior parafoveal VD and disease duration in migraine patients. Migraine with aura was associated with optic disc rim changes, but without any remarkable foveal vascular decrements. It is possible for migraine to cause structural changes due to its chronic nature.

Optic Nerve Head and Retinal Abnormalities Associated with Congenital Fibrosis of the Extraocular Muscles.

Congenital fibrosis of the extraocular muscles (CFEOM) is a congenital cranial dysinnervation disorder caused by developmental abnormalities affecting cranial nerves/nuclei innervating the extraocular muscles. Autosomal dominant CFEOM arises from heterozygous missense mutations of KIF21A or TUBB3. Although spatiotemporal expression studies have shown KIF21A and TUBB3 expression in developing retinal ganglion cells, it is unclear whether dysinnervation extends beyond the oculomotor system. We aimed to investigate whether dysinnervation extends to the visual system by performing high-resolution optical coherence tomography (OCT) scans characterizing retinal ganglion cells within the optic nerve head and retina. Sixteen patients with CFEOM were screened for mutations in KIF21A, TUBB3, and TUBB2B. Six patients had apparent optic nerve hypoplasia. OCT showed neuro-retinal rim loss. Disc diameter, rim width, rim area, and peripapillary nerve fiber layer thickness were significantly reduced in CFEOM patients compared to controls (p < 0.005). Situs inversus of retinal vessels was seen in five patients. Our study provides evidence of structural optic nerve and retinal changes in CFEOM. We show for the first time that there are widespread retinal changes beyond the retinal ganglion cells in patients with CFEOM. This study shows that the phenotype in CFEOM extends beyond the motor nerves.

Age-related Changes of Macular Ganglion Cell-inner Plexiform Layer Thickness in Korean Elderly Subjects.

Purpose We sought to establish normative ranges of the ganglion cell-inner plexiform layer (GCIPL) thickness using spectral-domain optical coherence tomography in Korean elderly individuals and to identify factors that influence GCIPL thickness.Methods We conducted a retrospective, observational study of 114 healthy subjects (75 years old or older) who underwent comprehensive ophthalmic examinations at a single institution. GCIPL thickness was measured with the Cirrus spectral-domain optical coherence tomography system and automatic segmentation. Subjects were divided into two age groups: those younger than 80 years and those 80 years or older, respectively. A cross-sectional analysis was adopted to evaluate associations of GCIPL thickness with sex, age, intraocular pressure, optic disc rim area, axial length, spherical equivalent (SE) refractive errors, astigmatism, and body mass index.Results The average and minimum GCIPL thicknesses were 80.3 ± 5.6 µm and 76.3 ± 5.9 µm, respectively. The GCIPL thickness was significantly lower in the older group than in the younger group in the inferior, inferonasal, and inferotemporal segments (all p < 0.01). A thinner average GCIPL thickness was strongly associated with increasing age (β = -2.87, p = 0.021) and thinner circumpapillary retinal nerve fiber layer thickness (β = 2.87, p < 0.001) in all segments.ConclusionsGCIPL thickness decreased with age globally and in all segments, even after 75 years of age. Thinner GCIPL was associated with older age and thinner circumpapillary retinal nerve fiber layer. Age-related changes should be considered when using GCIPL thickness to assess glaucoma and other optic neuropathies characterized by retinal ganglion cell loss.

Clinical and Optic Disc Characteristics of Patients Showing Visual Recovery in Leber Hereditary Optic Neuropathy.

The visual prognosis in Leber hereditary optic neuropathy (LHON) is generally poor. However, some individuals can have spontaneous visual recovery (VR) in one or both eyes by a mechanism that is not yet clearly understood. The purpose of this study was to determine whether certain clinical and optic disc features are associated with VR in patients with LHON. We retrospectively examined 80 eyes of 40 patients with LHON using clinical databases, fundus photographs, and high-definition spectral-domain optical coherence tomography (OCT) images. VR was defined as a gain of 3 or more lines of logarithm of the minimum angle of resolution (logMAR)-scaled visual acuity from nadir; this represents a doubling of the visual angle. Patients were divided into VR and nonrecovery (NR) groups. Using fundus photographs, we measured optic disc size and evaluated for the presence of optic disc features, including peripapillary telangiectasia, disc hyperemia, and swelling. We also measured the disc area, cup-to-disc ratio, and rim area of the optic disc using OCT. Twenty-one of 80 eyes (26%) had a VR. The VR occurred within 2 years after onset in 81% of cases. The VR group showed younger age at onset (21 vs 29 years, P = 0.017) and better visual acuity at the nadir (1.39 vs 2.16 logMAR, P < 0.001) compared with the NR group. Optic disc features, particularly peripapillary telangiectasia (P = 0.027) and disc hyperemia (P = 0.006), were more prominent in the NR group. The cup-to-disc ratio was significantly smaller (0.64 vs 0.71, P = 0.004) and the rim area was significantly greater (1.17 vs 0.85 mm, P < 0.001) in the VR group compared with the NR group. A younger age at onset and a less severe reduction of visual acuity at the nadir were associated with a higher probability of VR. Presence of peripapillary telangiectasia and optic disc hyperemia may serve as predictive factors for poor visual prognosis in patients with LHON.

Relationship between ocular risk factors for glaucoma and optic disc rim in normal eyes

AimTo study relationships between reported risk factors for glaucoma and neuroretinal rim area in normal eyes.MethodsThe Kumejima study participants, 3762 of the 4632 eligible Kumejima residents 40 years and older,...

Agreement between Fourier-domain and swept-source optical coherence tomography used for optic nerve head measurements

To assess the correlation between optic nerve head measurements generated by Fourier-domain (FD) and swept-source (SS) optical coherence tomography (OCT) both in healthy Caucasian subjects and patients with primary open angle glaucoma (POAG). This was a cross-sectional study of the right eyes of 118 subjects. In each participant, the measurements of disc area, cup to disc ratio (CDR), vertical cup to disc ratio (VCDR), rim area and rim volume were performed consecutively by FD-OCT and then SS-OCT. Participant age, gender and spherical equivalent were also recorded. Agreement between the two devices was assessed through intraclass correlation coefficients (ICC) and Bland-Altman plots. The study sample consisted of 95 healthy eyes and 23 eyes with glaucoma. Mean participant age was 48.6±20.0 years, 54.2% were female, and mean spherical equivalent was -1.6±3.0 diopters. FD-OCT and SS-OCT measurements were respectively: mean disc area 1.79±0.3 vs 1.83±0.3 mm2 (ICC=0.71), mean CDR 0.38±0.2 vs 0.33±0.2 (ICC=0.91), mean VCDR 0.58±0.2 vs 0.52±0.2 (ICC=0.92), mean rim area 1.05±0.4mm2 vs 1.03±0.5mm2 (ICC=0.29), and mean rim volume 0.14±0.11 vs 0.21±0.17mm3 (ICC=0.53). Good agreement between the devices was noted for rim area and rim volume in glaucoma subjects (ICC=0.76 and 0.68 respectively), while weak agreement was observed for these variables in healthy subjects (ICC≤0.50). The CDR and VCDR measurements provided by FD and SS OCT showed excellent agreement for the overall sample. When the devices were used for rim measurements, agreement was excellent only in the POAG patients.

Lamina Cribrosa Depth and Shape in Glaucoma Suspects. Comparison to Glaucoma Patients and Healthy Controls

ABSTRACT Purpose To evaluate the lamina cribrosa depth and shape parameters in glaucoma suspects compared to glaucoma patients and healthy controls. Materials and Methods A total of 325 subjects (120 with primary open-angle glaucoma, 103 glaucoma suspects and 102 healthy controls) were included. Serial horizontal B-scan images of optic nerve head were obtained using enhanced depth imaging of the optical coherence tomography. For each of the 325 subjects, lamina cribrosa position was measured manually in 16 horizontal B-scans, hence 5200 scans in total were analyzed. In particular, lamina cribrosa depth (LCD), lamina cribrosa deflection depth (LCDD), lamina cribrosa shape index (LCSI), and its horizontal equivalent (LCSIH) were estimated. Along lamina cribrosa parameterization, intraocular pressure, visual field, central retinal thickness, retinal nerve fiber layer thickness, and disc and neuroretinal rim areas were also measured. Results LCD was statistically significant different (P < .001) in glaucoma patients when compared to glaucoma suspects and heathy controls (603 ± 172 μm versus 554 ± 114 μm and 531 ± 115 μm, respectively). Similarly, LCDD was statistically significant different (P < .001) in glaucoma patients when compared to glaucoma suspects and heathy controls (250 ± 78 μm versus 213 ± 54 μm and 211 ± 58 μm, respectively). No statistically significant differences were found in LCSI (P = .957). However, LCSIH showed statistically significant differences between healthy controls and glaucoma suspects (P = .003) and between healthy controls and glaucoma patients (P = .006). Conclusions The deformation of LC in glaucoma suspects, in terms of LCSIH, was not statistically different from that of glaucoma patients. LCD does not have the potential to discriminate glaucoma suspects from healthy controls.

Relationship between retinal vessel diameter with both retinal nerve fibre layer thickness and optic nerve head parameters in middle-aged Caucasians: the Northern Finland Birth Cohort Eye study.

PurposeTo study the normal relationship between retinal vessel diameter (RVD) with retinal nerve fibre layer (RNFL) thickness and optic nerve head (ONH) parameters in a cohort of middle‐aged Caucasians.MethodsWe investigated 3070 individuals (6140 eyes). Central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were measured in the right eye using a semi‐automated computer‐assisted program. Retinal nerve fibre layer (RNFL) thickness and ONH parameters were assessed with Heidelberg retinal tomography (HRT).ResultsData from 2217 persons were analysed including RNFL, CRAE, CRVE, sex, body mass index, mean arterial pressure, diabetes status, smoking status, optic disc area, rim area, spherical refraction and intraocular pressure. A larger RVD was associated with a thicker mean global RNFL thickness especially in global and inferior segments of the retina and with larger optic discs. Each 10 μm increase in the retinal arteriolar calibre was associated with a 5.58 μm increase in mean global RNFL thickness; the corresponding value for a 10 μm increase in venular calibre was 3.79 μm (p < 0.001 for both). Retinal venular calibre displayed consistent associations with RNFL thickness in both genders (p < 0.001 for all), whereas the association of arteriolar calibre and RNFL was more prominent in men (p < 0.001).ConclusionWe found strong associations between larger RVD and thicker RNFL in all subjects. This study helps to clarify the association between RVD, RNFL thickness and ONH parameters and provides normal values for middle‐aged Caucasians that will help in future studies investigating the role of vascular aetiology in systemic and eye diseases.

A Common Glaucoma-risk Variant of SIX6 Alters Retinal Nerve Fiber Layer and Optic Disc Measures in a European Population: The EPIC-Norfolk Eye Study.

A common missense variant in the SIX6 gene (rs33912345) is strongly associated with primary open-angle glaucoma (POAG). We aimed to examine the association of rs33912345 with optic disc and retinal nerve fiber layer (RNFL) measures in a European population. We examined participants of the population-based EPIC-Norfolk Eye Study. Participants underwent confocal laser scanning tomography (Heidelberg Retina Tomograph II, HRT) to estimate optic disc rim area and vertical cup-disc ratio (VCDR). Scanning laser polarimetry (GDxVCC) was used to estimate average RNFL thickness. The mean of right and left eye values was considered for each participant. Genotyping was performed using the Affymetrix UK Biobank Axiom Array. Multivariable linear regression with the optic nerve head parameter as outcome variable and dosage of rs33912345 genotype as primary explanatory variable was used, adjusted for age, sex, disc area, axial length, and intraocular pressure. We further repeated analyses stratified into age tertiles. In total, 5433 participants with HRT data and 3699 participants with GDxVCC data were included. Each "C" allele of rs33912345 was associated with a smaller rim area (-0.030 mm [95% CI -0.040, -0.020]; P=5.4×10), a larger VCDR (0.025 [95% CI 0.017, 0.033]; P=3.3×10) and a thinner RNFL (-0.39 μm [95% CI -0.62, -0.15]; P=0.001). The RNFL association was strongest in the oldest age tertile, whereas rim area and VCDR associations were strongest in the youngest and oldest age tertiles. The protein-coding SIX6 variant rs33912345, previously associated with POAG, has a functional effect on glaucoma-associated optic nerve head traits in Europeans.

Reliability of Vessel Density Measurements in the Peripapillary Retina and Correlation with Retinal Nerve Fiber Layer Thickness in Healthy Subjects Using Optical Coherence Tomography Angiography

Purpose: To evaluate the reliability of vessel density measurements in the peripapillary retina using optical coherence tomography angiography (OCT-A) and to analyze the correlation with retinal nerve fiber layer (RNFL) thickness in healthy subjects. Method: Thirty-five healthy volunteers were recruited in the study. The optic disc region was scanned three times with spectral-domain OCT (SD-OCT) and split-spectrum amplitude decorrelation angiography by two skilled examiners. Vessel density of the peripapillary retina was automatically calculated by the software RTVue-XR (version 2015.1.1.98). The RNFL thickness on the optic nerve head was measured by SD-OCT. The coefficient of variation (CV), coefficient of repeatability, and intraclass correlation coefficients (ICC) were calculated for intraobserver repeatability. The Bland-Altman analysis was used to determine interobserver reproducibility. Correlations between peripapillary retinal vessel density and RNFL thickness were analyzed using a multivariable linear regression. Results: The mean age of the volunteers was 47.0 ± 29.7 years. The intraobserver repeatability in different sectors of the peripapillary retina was good with a high coefficient of repeatability, low CV (< 0.2%), and high ICC (0.847–0.952). The interobserver reproducibility was also good in different sectors, but should be interpreted with caution due to the difference bias caused by different observers in some quadrants. There was a significant positive correlation between vessel density and RNFL thickness; optic disc rim area and disc area were negatively related to vessel density (p = 0.008 and p = 0.001, respectively). Conclusion: Vessel density measurements showed good repeatability and reproducibility by OCT-A in the peripapillary retina, the vessel density was positively related to RNFL thickness and negatively related to optic disc area and rim area.

Racial differences in the correlations between structural parameters and ocular blood flow in healthy eyes

Purpose: This study aimed to assess differences in the relationship between structural parameters and ocular blood flow between persons of African (AD) and European descent (ED) with healthy eyes.Methods: The relationship between structural and ocular blood flow parameters was assessed in 46 participants (20 AD, 26 ED) with healthy eyes. Disc area (DA), rim area (RA), and retinal nerve fiber layer (RNFL) thickness were measured. Retrobulbar blood flow was assessed in the ophthalmic (OA), central retinal (CRA), nasal (NPCA) and temporal short posterior ciliary arteries (TPCA). Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistive index (RI) were assessed. Retinal capillary blood flow was also evaluated. Differences between the correlations were determined using the Fisher r-to-z transformation.Results: Significant differences in correlations were observed between the AD and ED groups in the CRA, where PSV and DA were positively correlated in AD (r=0.43) and negatively correlated in ED (r=-0.36) (Δr=0.79; P=0.01). A similar finding was observed for PSV and RA (AD: r=0.39; ED: r=-0.23; Δr=0.62; P=0.04). In the inferior hemifield for ED group only, percentage of avascular space and RNFL thickness were positively correlated (r=0.51, P=0.01) and mean retinal flow and RNFL thickness were negatively correlated (r=-0.50, P=0.01).Conclusion: The relationship between structural parameters and the blood supply to the superficial layer of the retina was significantly different in the healthy eyes of AD compared to ED. More research is required to show how these differences may affect glaucomatous risk.

Comparing characteristics of the optic nerve head among subjects with suspected glaucoma in different ages of onset

Introduction/Objective. Evaluation of the optic nerve head (ONH) is an inevitable procedure in the diagnosis of glaucoma. One of the most common imaging techniques for a quantitative assessment of the topography of the ONH is the Heidelberg retinal tomography II (HRT II). The aim of this study was to determine quantitative stereometric parameters of the ONH by using the HRT II and to investigate any damage of neuroretinal rim in children with suspected glaucoma and compared these data with the group of adults with suspected glaucoma. Methods. This comparative study included 167 (167 eyes) children aged 11?3 years with suspected juvenile glaucoma and 175 adult participants (175 eyes), aged 60?3 years, also with suspected glaucoma, examined between January 2013 and April 2014. Optic nerve head topography and retinal nerve fiber layer thickness measurements were assessed using a HRT II. Results. Data analysis in this study showed that the average mean values for children/adults were: disc area (mm2) 2.828?0.489/2.663?0.412 (p&lt;0.001); rim area (mm2) 1.873?0.391/1.667?0.275 (p&lt;0.001); cup/disc area ratio 0.369?0.125/0.369?0.101 (p=0.530); mean retinal nerve fiber layer thickness (mm) 0.223?0.078/0.219?0.055 (p=0.494). Statistically significant difference in damage of neuroretinal rim, between children and adults, was found in temporal (T) and temporal-inferior (Ti) segments. Conclusions. There were differences in some of the investigated quantitative parameters of the ONH between children and adults, as optic disc size, cup and rim area and rim volume. By using MRA, difference in the damage of the neuroretinal rim, when comparing children and adult optic discs appeared only in T and Ti segments, which means that optic disc cupping has spread more in children than in adults.