Thickness In Healthy Eyes Research Articles

Choroidal Thickness in Healthy Eyes Measured by Widefield Optical Coherence Tomography

Plain Language SummaryThe choroid is the vascular tissue between the retina and the sclera, with one of the most important functions being the nourishment of the external retinal layer. It is affected in ocular diseases and may be visualized using optical coherence tomography (OCT) technology. In this study, a new OCT instrument provided by Canon Corp, Tokyo, Japan was used that permitted a wider, up to 23 mm, field of view. The aim of the present research article was to analyze by measuring both manual and automatic, using a built-in software of the OCT, the thickness of the choroid up to the periphery in healthy eyes. The variation of the choroid with age, the thickest sector, and the validity of the automatic compared with the manual measurements were studied. Choroidal thickness (CT) decreases with age, the most significant variation occurring at 40 years of age. We found that the subfoveolar region is not always the thickest; in our sample, the superior sector was thickest in 62% of the eyes. The automatic and manual measurements were similar, therefore, the automatic system of the new OCT instrument may be valid.

Association between chromatic sensitivity and peripapillary retinal nerve fibre layer thickness in healthy eyes

Purpose: Knowledge of the retinal structure—chromatic sensitivity relationship of healthy eyes would be important for early detection of retinal neuropathies such as glaucoma. This study investigated the association between colour vision thresholds and the thicknesses of the retina in healthy young eyes.Methods: Measurements were made in 56 healthy eyes of 56 young subjects of mean age 25 ± 2.4 years (range 20–31 years), and distance visual acuity ≤0.1 logMAR. Chromatic sensitivity was measured using the Color Assessment and Diagnosis (CAD) test. The macular thicknesses of the central fovea, parafovea, and macular ganglion cell complex (mGCC), and the thickness of the peripapillary retinal nerve fibre layer (pRNFL) were measured by spectral‐domain optical coherence tomography (SD‐OCT). Relationships between red‐green (RG) and yellow‐blue (YB) thresholds and the retinal thicknesses were examined through Spearman correlation.Results: Significant correlations were detected between pRNFL thickness, in the inferior hemisphere, and the RG and YB‐thresholds (r = −0.30, p = 0.03 and r = −0.31, p = 0.02; respectively). Decreased pRNFL thickness correlated with worse colour thresholds. No significant correlations were found between macular thicknesses and colour thresholds.Conclusions: Greater inferior pRNFL thickness was related to better chromatic sensitivity in healthy eyes of young subjects.

Agreement, repeatability, and reproducibility of quantitative retinal layer assessment using swept-source and spectral-domain optical coherence tomography in eyes with retinal diseases.

To evaluate the agreement and precision of retinal thickness measurements obtained using swept-source optical coherence tomography (SS-OCT) and spectral-domain OCT (SD-OCT) in healthy eyes and eyes with retinopathy. This cross-sectional prospective study involved three DRI-OCT Triton (SS-OCT) and three 3D-OCT-1 Maestro (SD-OCT) devices. One of each device (Maestro and Triton) was paired with a single operator. Healthy subjects and patients with retinal diseases were recruited, with study eye and testing order randomized. At least 3 scans per eye were captured for wide scan (12 mm × 9 mm-Triton and Maestro) and macular cube scan (7 mm × 7 mm-Triton, 6 mm × 6 mm-Maestro). Thickness of the full retina, ganglion cell layer + inner plexiform layer (GCL+), and ganglion cell complex (GCL++) were obtained from wide scan and cube scans. Agreement of the measurements between the Triton and Maestro was evaluated by Bland-Altman analysis and Deming regression for each group. Repeatability and reproducibility were assessed using a two-way random effect analysis of variance (ANOVA) model for each parameter by group. Twenty-five healthy subjects (25 eyes) and 26 patients with retinal diseases (26 eyes), including, but not limited to, age-related macular degeneration, macular hole, and diabetic retinopathy were recruited. Overall, the measurement differences between Triton and Maestro were <6 μm (mean differences of full retina, GCL++, and GCL+ thickness were ≤5.5 μm, 1.3 μm, and 2.8 μm, respectively) and not statistically significant across the parameters. The repeatability and reproducibility estimates indicate high precision in both devices and groups. Across all the parameters, the repeatability limit was ≤7.6 μm for Triton and ≤12.7 μm for Maestro; reproducibility limit was ≤9.2 μm for Triton and ≤14.4 μm for Maestro. In eyes with retinal pathology, the repeatability coefficient of variation (CV)% was ≤2.6% for Triton and ≤3.4% for Maestro; reproducibility CV% was ≤3.3% for Triton and ≤3.5% for Maestro. Both Triton SS-OCT and Maestro SD-OCT provide reliable measurements of retinal thickness in healthy eyes and eyes with retinal diseases. Excellent agreement between the two devices indicates interoperability when testing healthy eyes or eyes with retinal pathology. These findings support the use of thickness measurements from Triton SS-OCT and Maestro SD-OCT in clinical practice.

Association between dietary niacin and retinal nerve fibre layer thickness in healthy eyes of different ages.

To investigate the relationship between dietary intake of niacin (water-soluble form of vitamin B3 ) and retinal nerve fibre layer (RNFL) thickness in healthy eyes. This cross-sectional study examined the association between daily niacin intake and RNFL thickness in three large population-based cohorts with varied age differences. RNFL thickness was extracted from optical coherence tomography data; energy-adjusted niacin intake was estimated from food frequency questionnaires. Linear mixed-effects models were utilised to examine the association between RNFL thickness and energy-adjusted niacin intake. Three separate analyses were conducted, with niacin treated as a continuous, a categorical (quartiles) or a dichotomous (above/below Australian recommended daily intake) variable. In total, 4937 subjects were included in the study [Raine Study Gen2, n=1204, median age 20; Busselton Healthy Ageing Study (BHAS), n=1791, median age 64; TwinsUK, n=1942, median age 64). When analysed as a continuous variable, there was no association between RNFL thickness and niacin intake in any of the three cohorts (95% CI β: Raine Study Gen 2, -0.174 to 0.074; BHAS, -0.066 to 0.078; TwinsUK -0.435 to 0.350). Similar findings were observed with quartiles of niacin intake and for niacin intakes above or below Australian recommended daily intake levels in all three cohorts. Dietary intake of niacin from a standard diet does not appear to be associated with age-related RNFL thinning in healthy eyes. Supraphysiological doses of niacin may be required for therapeutic effect in the retina.

Automatic Segmentation of Choroid Layer Using Deep Learning on Spectral Domain Optical Coherence Tomography

The purpose of this article is to evaluate the accuracy of the optical coherence tomography (OCT) measurement of choroidal thickness in healthy eyes using a deep-learning method with the Mask R-CNN model. Thirty EDI-OCT of thirty patients were enrolled. A mask region-based convolutional neural network (Mask R-CNN) model composed of deep residual network (ResNet) and feature pyramid networks (FPNs) with standard convolution and fully connected heads for mask and box prediction, respectively, was used to automatically depict the choroid layer. The average choroidal thickness and subfoveal choroidal thickness were measured. The results of this study showed that ResNet 50 layers deep (R50) model and ResNet 101 layers deep (R101). R101 U R50 (OR model) demonstrated the best accuracy with an average error of 4.85 pixels and 4.86 pixels, respectively. The R101 ∩ R50 (AND model) took the least time with an average execution time of 4.6 s. Mask-RCNN models showed a good prediction rate of choroidal layer with accuracy rates of 90% and 89.9% for average choroidal thickness and average subfoveal choroidal thickness, respectively. In conclusion, the deep-learning method using the Mask-RCNN model provides a faster and accurate measurement of choroidal thickness. Comparing with manual delineation, it provides better effectiveness, which is feasible for clinical application and larger scale of research on choroid.

Retinal Nerve Fiber Layer Thickness in Healthy Eyes of Black, Chinese, and Latino Americans: A Population-Based Multiethnic Study

To compare peripapillary retinal nerve fiber layer (RNFL) thickness among healthy adults by race and ethnicity and to identify determinants of RNFL thickness. Population-based cross-sectional study. Data from 6133 individuals (11 585 eyes) from 3 population-based studies in Los Angeles County, California, 50 years of age or older and of self-described African, Chinese, or Latin American ancestry. We measured RNFL thickness and optic nerve head parameters using the Cirrus HD-OCT 4000. Multivariate linear mixed regression was used to evaluate factors associated with RNFL thickness among participants without ocular diseases. Determinants and modifiers of RNFL thickness. The mean age of the participants was 60.1 years (standard deviation, 7.4 years). Black Americans showed the lowest RNFL thickness and smallest cup-to-disc ratio (CDR), and Chinese Americans showed the largest CDR and disc area after adjusting for age and gender (all P < 0.05). Per each 10-year older age group, the average RNFL thickness was 2.5 μm (95% confidence interval [CI], 1.8-3.1 μm), 2.8 μm (95% CI, 2.3-3.3 μm), and 3.5 μm (95% CI, 2.9-4.1 μm) thinner for Black, Chinese, and Latino Americans, respectively (age trend P < 0.05 and interaction P= 0.041). Black Americans compared with Chinese Americans, older age, male gender, hypertension, diabetes, greater axial length (AL), bigger disc area, and lower scan signal strength were associated with thinner average RNFL. Race, age, AL, disc area, and scan signal strength consistently were associated with RNFL thickness in all quadrants, whereas gender, hypertension, and diabetes were associated with RNFL thickness in select quadrants. Age and race explained the greatest proportion of variance of RNFL thickness. Clinically important differences in RNFL thickness are present in healthy adults 50 years of age or older from different racial and ethnic groups of the same age, with the thinnest measures observed in Black Americans. This difference remains after accounting for disc size and AL. Furthermore, age-related RNFL thinning differs by race and ethnicity. Longitudinal studies are needed to verify our findings and to assess the influence of race and ethnicity in the clinical application of RNFL thickness.

The correlation of radial peripapillary capillary density measurements with optic nerve head morphology and retinal nerve fiber layer thickness in healthy eyes.

To investigate the association between radial peripapillary capillary plexus (RPC) density and optic nerve head morphology in healthy eyes using optical coherence tomography angiography (OCTA). One hundred twenty-seven eyes of 64 volunteers were included in the study. The retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters were measured using Cirrus 5000 HD OCT with Angioplex angiography. RPC perfusion and flux index were assessed using the 4.5 × 4.5 mm scan acquisition protocole. SPSS 25.0 version for Windows was used for statistical analysis. There was a significant positively correlation between the mean overall RPC perfusion and FI the mean average RNFL thickness (r = 0.417, p < 0.001 and r = 0.239, p = 0.007, respectively). The mean rim area was significantly positively correlated with the mean overall RPC perfusion and FI (r = 0.308 p < 0.001 and r = 0.233 p = 0.008, respectively). There was a significant negatively correlation between cup volume and the mean overall FI (r = - 0.218 p = 0.01). Our study shows that not only RNFL thickness, but the density of RPCs network may also be associated with ONH parameters. OCTA analysis may be a useful method to clarify these associations quantitatively.

Wide-field individual retinal layer thickness in healthy eyes.

To report the individual retinal layer thickness in healthy subjects using wide-field optical coherence tomography. This was a prospective, cross-sectional study involving healthy subjects. A custom-designed semiautomated segmentation algorithm was used to split the retinal layers in seven bands, and individual retinal layer thicknesses were measured in horizontal (nasal, macular, and temporal segments) and vertical meridians (superior, macular, and inferior segments). The variation in retinal thickness was analyzed in different segments at an interval of 1 mm from reference points. Regression analysis was performed to identify the factors affecting retinal thickness. Twenty eyes of 20 healthy subjects with mean age of 28.9 ± 6.3years were analyzed. Overall, nasal and superior segments (mean ± standard deviation: 279.6 ± 17.0 and 234.4 ± 19.2 µm) had maximum and minimum retinal thicknesses, respectively. A total of seven bands were delineated in each optical coherence tomography b scan in each segment. Retinal nerve fiber layer was thickest immediately nasal to optic disk margin in horizontal scan (72.4 ± 32.4 µm) and near the vascular arcades in vertical meridian. Outer plexiform layer, external limiting membrane-ellipsoid zone and interdigitation zone-retinal pigment epithelium-Bruch's complex showed significant variation in both horizontal and vertical meridians (all p values <0.05). Macular segment in both meridians showed the highest coefficient of variation. Age was the only significant factor affecting retinal thickness in multiple regression analysis (p = 0.001). Wide-field optical coherence tomography shows significant regional variation in overall and individual retinal layer thicknesses in macular and peripheral areas in healthy eyes with the highest variation in macular segment.

Peripapillary Scleral Bowing Increases with Age and Is Inversely Associated with Peripapillary Choroidal Thickness in Healthy Eyes

To use optical coherence tomography (OCT) to 3-dimensionally characterize the optic nerve head (ONH) in peripapillary scleral bowing in non-highly myopic healthy eyes. Cross-sectional, multicenter study. A total of 362 non-highly myopic (+6 diopters [D] > spherical equivalent >-6D) eyes of 362 healthy subjects from 20-90 years old underwent OCT ONH radial B-scan imaging. Bruch's membrane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and the peripapillary scleral surface were segmented. BMO and ASCO planes were fit, and their centroids, major axes, ovality, areas and offsets were determined. Peripapillary scleral bowing was characterized by 2 parameters: peripapillary scleral slope (ppSS) of 3 anterior peripapillary scleral segments (0-300, 300-700, and 700-1,000μm from the ASCO centroid); and ASCO depth relative to a peripapillary scleral reference plane (ASCOD-ppScleral). Peripapillary choroidal thickness (ppCT) was calculated relative to the ASCO as the minimum distance between the anterior scleral surface and BM. Both ppSS and ASCOD-ppScleral ranged from slightly inward through profoundly outward in direction. Both parameters increased with age and were independently associated with decreased ppCT. In non-highly myopic healthy eyes, outward peripapillary scleral bowing achieved substantial levels, was markedly increased with age, and was independently associated with decreased peripapillary choroidal thickness. These findings provide a normative foundation for characterizing this anatomy in cases of high myopia and glaucoma and in eyes with optic disc tilt, torsion, and peripapillary atrophy.

Normative values of the retinal macular thickness in a middle eastern population

BackgroundSince the normative value of the retinal macular thickness is undocumented in the Middle East, the aim of this work is to assess the normative values of the macular thickness in healthy eyes in a Middle Eastern population and its relationship with age, sex, and laterality.MethodsOne hundred sixteen individuals were randomly selected from volunteers visiting the Jordan University Hospital in Amman, Jordan. Measurements were obtained using the Fourier domain optical coherence tomography (OCT). Multivariate regression models were developed to obtain predicted normative values with adjustment to candidate variables. In addition, the effect of age, sex and laterality were evaluated.ResultsThe average central fovea macular thickness was 229.5 (±30.85) um. The quadratic value of the retinal macular thickness decreased from the superior value of 299.71 (±23.67) um (P = .001) to the inferior value of 296.46 (±28.85) um(P = .001) and a nasal figure of 93.63 (±26.86) um(P = .001). The temporal area has the thinnest value of 293.43 (±30.78) um (P = 0.001). Central thickness was higher in males with a mean variation of 11.67 um (95% CI, 2.41 to 20.93) (p = 0.003). The thickness was highest within 3 mm diameter from the center and decreased towards the periphery Eye sidedness didn’t contribute to variability of the macular thickness. Furthermore, we found a significant difference between age and central macular thickness (p = 0.001), as age was a positive predictor for macular thickness.ConclusionOur set of predicted normative data may be used to interrupt measurement of the macular thickness in Middle Eastern population. The average fovea macular thickness among Jordanians is consistent with previously reported values. Normative values from additional Middle Eastern. Population are required to appraise our model.

Myopia and Regional Variations in Retinal Thickness in Healthy Eyes.

Purpose To investigate the effects of refraction on retinal thickness measurements at different locations and layers in healthy eyes of Saudi participants.MethodsThirty-six randomly selected adults aged 27.0 5.7 years who attended a Riyadh hospital from 2016 to 2017 were categorized into three groups: non-myopic (spherical equivalent refraction [SER], +1.00 to –0.50 diopters [D]), low myopic (SER, –0.75 to –3.00D), and moderate to high myopic (SER –3.25D). Full, inner, and outer retinal thicknesses were measured at nine locations by spectral-domain stratus optical coherence tomography (Optovue Inc., Fremont, CA, USA) and were compared according to refractive group and sex.ResultsThe mean SERs for the non-myopia, low myopia, and moderate to high myopia groups were 0.2 0.6, –1.5 0.5, and –7.5 1.9 D, respectively. Refractive error, but not sex, had significant effects on the retinal layer thickness measurements at different locations (P 0.05). The parafoveal and outer retinal layers were significantly thicker than the perifoveal and inner retina layers in all groups (P 0.05). The full foveal thickness was higher and the full parafoveal and perifoveal regions were thinner in moderate to high myopic eyes than in the non-myopic eyes (P 0.05), but were similar to those in the low myopic eyes (P 0.05). The foveal thicknesses measured in the inner and outer layers of the retina were higher but the thicknesses measured at the inner and outer layers of the parafoveal and perifoveal regions were lower in moderate to high myopic eyes.Conclusion There were regional differences in the retinal layer thicknesses of healthy Saudi eyes, which was dependent on the central refractions. This is important when interpreting retinal nerve fiber layer thicknesses in myopia and disease management in Saudi participants.

Topographic Variations of Choroidal Thickness in Healthy Eyes on Swept-Source Optical Coherence Tomography.

PurposeTo assess topographic variations of choroidal thickness (CT) in the fovea and beyond in healthy eyes.MethodsThis cross-sectional study included healthy subjects ≤ 55 years of age with axial lengths (22–26 mm) and refractive error margins (–4D, +4D) in normal ranges. Images were acquired using swept-source optical coherence tomography angiography (OCT-A). Corneal thickness (CT) maps from 12 × 12-mm radial scans and 9 × 9-mm OCT-A B-scans were analyzed.ResultsThe study included 64 eyes of 33 subjects (mean age, 37 years). Mean CT was >300 µm in all locations except the nasal outer macula. The subfoveal CT was >395 µm in 30% of cases; in 38.7% of cases, >50% of the CT map was thicker than 395 µm. The mean thickest choroidal point was 395.2 µm (range, 164–548 µm), located superior and temporal to the macula in 72.2% of cases and subfoveally in 1.8% of cases. The CT pattern was symmetrical (58%) or asymmetrical (42%) along a horizontal axis correlating with choroidal vein distribution. Half of the asymmetrical patterns were thicker in the inferior quadrants, with an oblique temporal watershed of venous drainage, and the other half were thicker superiorly. The mean vascularity index was ∼75% regardless of the mean CT.ConclusionsOne-third of healthy eyes of patients younger than age 55 had a thick choroid (>395 µm). In these normal eyes, the thickest choroidal point was not subfoveal, CT symmetry above and below the fovea depended on choroidal vein distribution, and choroidal vascularity index was independent from CT. No patients demonstrated fundus autofluorescence abnormalities, and the choriocapillaris remained visible even in thick choroids. These features could be interesting when differentiating normal versus pathological states.

Widefield topographical analysis of the retinal perfusion and neuroretinal thickness in healthy eyes: a pilot study.

In this pilot study we reported variation of superficial (SCP) and deep (DCP) capillary plexuses flow in macular and near/mid periphery regions in healthy subjects using widefield swept source-optical coherence tomography angiography (SS-OCTA). In this prospective, cross-sectional study, enroled subjects were imaged with an SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). OCTA scans were taken in primary and extremes of gaze and a montage was automatically created. Quantitative analysis was performed in the macular and peripheral regions. In addition, SCP and DCP variables were further investigated in distinct fields within these three different regions. Fifty-five young healthy subjects (55 eyes) were enroled. The retinal periphery displayed a higher SCP perfusion density (39.6 ± 1.7% and 40.7 ± 1.4%, P < 0.0001) and SCP vessel diameter index (3.5 ± 0.2 and 3.6 ± 0.2, P < 0.0001), in comparison with the macular region. At the DCP level, the retinal periphery was characterized by a lower perfusion density (41.6 ± 3.7% and 37.9 ± 2.9%, P < 0.0001) and vessel length density (14.6 ± 6.0% and 9.9 ± 2.6%, P < 0.0001). In the analysis investigating the DCP in the retinal periphery, the temporal sector was characterized by a reduction in perfusion density, vessel length density, and vessel diameter index. In univariate analysis, the retinal thickness was found to have a significant direct relationship with DCP perfusion density (P < 0.0001), but not with SCP perfusion density (P = 0.712). We report quantitative mapping of the SCP and DCP in healthy individuals. The DCP perfusion appears to have a wide topographical variation, which is strictly dependent on the retinal thickness.

Effects of axial length on retinal nerve fiber layer and macular ganglion cell-inner plexiform layer measured by spectral-domain OCT.

To evaluate the influence of ocular axial length on circumpapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness in healthy eyes after correcting for ocular magnification effect. In this cross-sectional study, we evaluated 120 eyes from 60 volunteer participants (myopes, emmetropes, and hyperopes). The thickness of the circumpapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer were measured using the spectral optical coherence tomography (OCT)-Cirrus HD-OCT and correlated with ocular axial length. Adjustment for ocular magnification was performed by applying Littmann's formula. Before the adjustment for ocular magnification, age-adjusted mixed models analysis demonstrated a significant negative correlation between axial length and average circumpapillary retinal nerve fiber layer thickness (r=-0.43, p<0.001), inferior circumpapillary retinal nerve fiber layer thickness (r=-0.46, p<0.001), superior circumpapillary retinal nerve fiber layer thickness (r=-0.31, p<0.05), nasal circumpapillary retinal nerve fiber layer thickness (r=-0.35, p<0.001), and average ganglion cell-inner plexiform layer thickness (r=-0.35, p<0.05). However, after correcting for magnification effect, the results were considerably different, revealing only a positive correlation between axial length and temporal retinal nerve fiber layer thickness (r=0.42, p<0.001). Additionally, we demonstrated a positive correlation between axial length and average ganglion cell-inner plexiform layer thickness (r=0.48, p<0.001). All other correlations were not found to be statistically significant. Before adjustment for ocular magnification, axial length was negatively correlated with circumpapillary retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness measured by Cirrus-OCT. We attributed this effect to ocular magnification associated with greater axial lengths, which was corrected with the Littman's formula. Further studies are required to investigate the impact of ocular magnification correction on the diagnostic accuracy of Cirrus-OCT.

Choroidal thickness in healthy eyes using enhanced depth imaging optical coherence tomography and comparison with cases of retinitis pigmentosa

The goal of this study was to measure by spectral domain optical coherence tomography (SD-OCT) with EDI the choroidal thickness in healthy subjects and to compare these parameters with those of patients with retinitis pigmentosa (RP). Data were obtained from 60 healthy patients without history or family history of retinal or choroidal disease or glaucoma. A case-control study was also conducted on 40 eyes of 20 patients with RP and 40 eyes of 20 healthy refraction- and age-matched controls, selected from among the 60 healthy patients. OCT was used with the EDI protocol. The primary outcome measure was choroidal thickness. Among healthy patients, the overall choroidal thickness was 287.7μm. Mean choroidal thickness was lower on the nasal side (236.6μm at 2000μm from the fovea) compared with the temporal side (262.3μm at 2000μm, P=0.002). It also varied according to age, being highest among 20-29-year-old patients and decreasing thereafter with increasing age. Choroidal thickness was significantly higher in healthy patients than in RP patients, regardless of the location (P<0.001). This observational study confirms that choroidal thickness varies with age and location. It decreases in subjects with RP and is related to worsening of retinal damage, independently of age-related thinning. Further studies are needed to understand whether choroidal vascular alteration is a cause or a consequence of the degenerative pathology.

Macular thickness in healthy eyes of adults (N=4508) and relation to sex, age and refraction: the Tromsø Eye Study (2007-2008).

PurposeTo provide sex‐stratified normative data on retinal thickness and study the relationship with sex, age and refractive status.MethodsPopulation‐based study including 2617 women and 1891 men, aged 38–87 (mean 61 ± 8) years, without diabetes, glaucoma and retinal diseases, and spherical equivalent refraction (SER) within ±6 dioptres. Retinal thickness was measured with optical coherence tomography (spectral domain Cirrus HD‐OCT).ResultsWomen had thinner retina than men. Retinal thickness was significantly associated with refraction, where mean change in retinal thickness per 1 D increase in SER was −1.3 (0.2) μm in the fovea, 0.7 (0.1) μm in the pericentral ring and 1.4 (0.1) μm in the peripheral ring. In the fovea, there was a non‐monotonic curved relationship between retinal thickness and age in both sexes with a maximum at about 60 years (p < 0.001). In the pericentral ring, the mean reduction in retinal thickness per 10‐year increase was 2.7 (0.3) μm in women and 4.0 (0.4) μm in men and corresponding results in the peripheral ring were 2.3 (0.3) μm in women and 2.6 (0.4) μm in men. In both regions, there was evidence for a nonlinear pattern with an increased rate of change with higher age. There was a significant interaction between sex and age for retinal thickness of the pericentral ring (p = 0.041).ConclusionWomen had thinner retina than men, and thickness varied with refractive status. Retinal thickness was associated with age in all macular regions, and the rate of change in retinal thickness varied at different ages.

Are there diurnal variations in choroidal thickness?

Measurement of diurnal choroidal thickness in healthy eyes to investigate thickness variations. A total of 30 healthy eyes in 30 subjects were examined at 6 predefined times within 24 h. Choroidal thickness was visualized using the 7-line scan of spectral domain optical coherence tomography (OCT) with enhanced depth imaging (Spectralis, Heidelberg Engineering) and manually measured by two independent observers. For statistical analyses the mean value was calculated. The mean choroidal thickness was 270 ± 87 µm. Choroidal thickness changes from baseline ranged between - 47 µm and + 41 µm. There was a statistically significant negative correlation between baseline choroidal thickness and the thickness in examinations at 10:30 am, 1:30 pm and 4:30 pm with the Spearman correlation test. Due to the large diversity in the individual diurnal fluctuations, a significant diurnal variation of choroidal thickness was not observed. There was a significant negative correlation between age and choroidal thickness. In this study a significant diurnal variation of choroidal thickness was not observed. Patient age correlated negatively with choroidal thickness.

Optical coherence tomography measurements of choroidal thickness in healthy eyes: correlation with age and axial length.

To evaluate subfoveal choroidal thickness (CT) in healthy eyes using spectral-domain optical coherence tomography (SD-OCT) and provide correlations between age and axial length. Enhanced depth SD-OCT imaging was performed with Cirrus (Carl Zeiss Meditec, Dublin, CA) and Spectralis (Heidelberg Engineering, Heidelberg, Germany) instruments. CT was measured from the outer limit of the retinal pigment epithelium to the inner surface of the sclera. The study enrolled 155 patients, with at least 20 in each decade between 22 and 89 years old. Mean axial length was 23.6 mm. Mean Heidelberg subfoveal CT was 286 µm. The correlation between Heidelberg and Zeiss subfoveal CT measurements was strong (r = .978) and significant (P < .001). Mean subfoveal CT was 7.7 µm thinner by Heidelberg versus Cirrus (P < .001). Multiple linear regression analysis revealed that age (P < .001), axial length (P = .001), and sex (P = .025) were significantly related to Heidelberg subfoveal CT. There is a strong negative correlation between CT and age (P <.001), with a 25 µm decrease in CT for each decade of life. Increasing axial length demonstrated a negative correlation with CT, decreasing 24.9 µm for each mm of axial length. Future studies of CT measurements can be performed on either instrument and must account for axial length, age, and sex to make appropriate conclusions.

Objective analyses of tessellated fundi and significant correlation between degree of tessellation and choroidal thickness in healthy eyes.

A tessellated fundus is a common characteristic of myopic eyes and is an important clinical marker for the development of retinochoroidal changes. However, the exact cause and significance of tessellated fundi have not been definitively determined. We determined the degree of tessellation in fundi objectively in normal, non-pathological myopic eyes, and correlated the degree of tessellation and the choroidal thickness (CT) and axial length (AL). This was a prospective observational cross sectional study. The eyes were classified subjectively into three groups based on the degree of tessellation observed ophthalmoscopically. Digital color fundus photographs were assessed for the degree of tessellation by ImageJ, an image processing program. Three tessellated fundus indices (TFIs) were calculated and were compared to the three subjectively-determined groups. The subfoveal and nasal CTs were measured in the optical coherence tomographic images. The correlations between the TFIs and the CT were calculated. Additionally, the correlation between the TFIs and the AL was calculated. One hundred right eyes of 100 healthy volunteers (mean age 25.8±3.9 years) were studied. Ophthalmoscopically, 57 eyes were placed in the non-tessellated group, 27 eyes into the weakly tessellated group, and 16 eyes into the strongly tessellated group. There was a significant correlation between the subjective classifications and the TFI values (P<0.05, Kruskal-Wallis test). All of the TFIs were significantly associated with the subfoveal and nasal CT (R = −0.20 to −0.24, P<0.05). The TFIs were not significantly correlated with the ALs. In conclusion, the significant correlation between the subjective and objective classifications of the degree of tessellation indicates that TFIs can be used to classify the degree of tessellation. The results indicate that the differences in the CT account for the degree of tessellation.

Relationship Between Position of Peak Retinal Nerve Fiber Layer Thickness and Retinal Arteries on Sectoral Retinal Nerve Fiber Layer Thickness

We determined the relationship between the position of the peak of the retinal nerve fiber layer (RNFL) thickness, and the retinal arteries, axial length (AL), and sectoral RNFL thickness in healthy eyes. A prospective, observational cross-sectional study (registration number, UMIN000006040) of 50 healthy right eyes (mean age 25.8 ± 3.7 years) was performed. The RNFL thickness was measured by optical coherence tomography in twelve 30° sectors (clock hours) around the optic disc. The RNFL nasal-superior-temporal-inferior-nasal curves and fundus photographs were used to measure the angles between the supratemporal and infratemporal peak RNFL positions (peak angle), and the retinal artery angle (artery angle), respectively. The relationships between the peak angle, artery angle, AL, and sectoral RNFL thickness were investigated by linear regression analyses. The peak angles were highly correlated with the artery angle (r = 0.92, P < 0.001) and correlated negatively with the AL (r = -0.49, -0.38; P < 0.01). After excluding the effect of the AL, the peak and artery angles were correlated significantly with the sectoral RNFL thickness in 8 sectors. After excluding the effect of the peak angle, the AL was correlated significantly with the sectoral RNFL thicknesses in only one sector. The temporal RNFL thickness increased as the superior and inferior RNFL peaks, and retinal arteries shifted toward the fovea, whereas an inverse relationship was observed for the inferior and supranasal areas. The sectoral RNFL thickness is correlated better with the peak and artery angles than the axial length. (https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary &recptno=R000007154&language=J number, UMIN000006040.).