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Salma Firdaus,1,&ast; Lívia Figueiredo Pereira,2,&ast; Ge Yang,3 Yumin Huang-Link4 1Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia; 2Pontifical Catholic University of Minas Gerais, Belo Horizonte, Brazil; 3Huizhou Aier Eye Hospital, Aier Eye Hospital Group, Huizhou, Guangdong Province, People’s Republic of China; 4Division of Neurology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden&ast;These authors contributed equally to this workCorrespondence: Ge Yang, Huizhou Aier Eye Hospital, Aier Eye Hospital Group, Huizhou, Guangdong Province, People’s Republic of China, Email geyang95@sina.comPurpose: To compare the interocular symmetry and investigate the intermachine reproducibility of optic disc and macular data measured by spectral-domain high-definition optical coherence tomography (HD-OCT) Cirrus HD-OCT 4000 and HD-OCT 5000 from healthy subjects.Patients and Methods: Forty-three volunteers were examined with both HD-OCT 4000 and HD-OCT 5000 at the same visit. Optic nerve head (ONH) and macular data were acquired using ONH Cube 200× 200 scans and macular volume cube 512× 128 scans, respectively.Results: The average age of the participants was 33 ± 8.6 years. Interocular OCT parameters of ONH and macula showed a high correlation between the right and left eyes regardless of HD-OCT models, displaying a low coefficient of variation (CV). However, the average retinal nerve fiber layer (RNFL) was thicker (96.67± 11.19μm vs 95.3± 10.89μm, p< 0.01), and the average central subfield thickness (261.51± 17.45μm vs 262.51± 17.39 μm, p< 0.01) and cube average thickness (283.91± 13.59μm vs 286.55± 13.09μm, p< 0.05) were thinner when measured by Cirrus 4000 compared to 5000. Intermachine reproducibility and reliability of RNFL and macular parameters exhibited a high intraclass correlation coefficient (ICC) (0.985) and low CV (2.4%). Ganglion cell-inner plexiform layer (GCIPL) measured by two OCT models showed similar values with an average thickness of 85 μm and had high intermachine reproducibility with high ICC (0.993) and low CV (1.2%).Conclusion: High interocular symmetry was observed across both HD-OCT models. Intermachine reproducibility for RNFL and all macular parameters was also high. GCIPL showed minimal intermachine differences with high reproducibility and reliability. Thus, the results imply that GCIPL values measured by two Cirrus OCT models may be used interchangeably.Keywords: neuro imaging, optical coherence tomography, interocular symmetry, intermachine reproducibility, retina, ganglion cell-inner plexiform layer, interchangeability

PurposeSystemic sclerosis (SSc) affects blood vessels, internal organs, and skin. In ophthalmology, SSc impacts the choroid. The choroidal vascularity index (CVI) measures the vascular component of the choroid and may serve as a biomarker for the disease staging and prognosis. Studies have reported reduced choroidal thickness and altered CVI in SSc, which supports the theory of vascular damage. This study aimed to examine interocular symmetry in choroidal parameters among SSc patients. It has provided the insight into the disease symmetry and assessed the representativeness of examining one eye.MethodsThis prospective single-center cross-sectional study included 33 patients with SSc and 40 healthy controls. The patients underwent ophthalmological examination (including refraction, visual acuity, IOP, biometry, slit-lamp biomicroscopy, dilated fundus examination, and spectral-domain optical coherence tomography) and rheumatological evaluation. Various parameters of the choroid in the macular and peripapillary regions were analyzed, including choroidal thickness, choroidal volume, and CVI. The interocular asymmetry in the choroidal parameters was quantified using signed and absolute differences. The correlation analysis between the left and right eyes was based on the intraclass correlation coefficient (ICC), Spearman’s correlation coefficient, and paired Wilcoxon test.ResultsThere were no significant differences in the macular and peripapillary choroidal parameters between fellow eyes in both SSc patients and controls (p > 0.05). The parameter that showed the lowest correlation among those examined was CVI—in both groups, as well as in both examined areas. The interocular correlation of choroidal parameters was stronger in the peripapillary area than in the macular area in both groups. In general, the results were confirmed in subgroup analyses stratified according to sex, SSc subtype, Scl70 antibody positivity and previous and/or active digital ulcers.ConclusionThere is interocular symmetry of the choroidal parameters in patients with SSc and controls included in our study. The parameters from one eye are representative of the fellow eye of a given patient. This conclusion may contribute to the design and interpretation of future studies. It also broadens our knowledge of SSc pathophysiology.

Purpose: The aim of this study was to investigate, using a power vector approach, whether corneal astigmatism follows a mirror symmetry pattern considering both the magnitude and axis, and whether age, sex and spherical equivalent refractive error can influence the pattern., Methods: The IOLMaster 700 optical biometer was used to measure the radii of curvature of the anterior corneal surface. Refractive error was determined by non-cycloplegic subjective refraction. Descriptive statistical analyses and inferential logistic regression were applied over the dichotomous variable of mirror symmetry using J 0 and J 45 power vector components. An evaluation was carried out based on the subject's age, sex and spherical equivalent refractive error., Results: A total of 2974 Caucasian adults were evaluated. This cross-sectional study revealed that axis orientation follows the isorule symmetry pattern, and in terms of both magnitude and axis orientation, mirror symmetry was present in 70.9% of cases. Age, sex and spherical equivalent refractive error were not significant factors and did not contribute to the clinical improvement of the model despite its statistical significance (refractive error, p = 0.001; age and sex, p = 0.23 and 0.36, respectively)., Conclusions: Among an adult Caucasian population, the prevalence of corneal astigmatism mirror symmetry was 70.9% and isorule symmetry was the most common pattern considering axis orientation only. The inclusion of age, sex and spherical equivalent refractive error did not improve the model., (© 2024 The Author(s). Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.)

PURPOSE: The purpose of the study was to obtain a pediatric reference database for optic disc parameters and interocular symmetry. To ascertain factors that modify these parameters (age, spherical equivalent [SE], and sex). METHODS: This was a cross-sectional study. 90 patients aged 5--17 years fulfilled all the inclusion criteria. After a full examination including cycloplegic refraction, all patients underwent optical coherence tomography (OCT) of the papilla using the three-dimensional (3D) scan protocol of the Topcon 3D 2000 OCT device. We provide reference values for optic disc parameters in the pediatric population. We also retrieved interocular symmetry reference values for these parameters. RESULTS: The multivariate regression analysis did not reveal variations in any of the optic disc parameters associated with age, sex, or SE (all P ≥ 0.126). The 95th percentile limit for absolute interocular differences for the cup-to-disc area ratio was 0.24. The multivariate regression analysis revealed the absence of a correlation between asymmetry of the optic disc parameters and age, sex, and the interocular difference in SE (all P ≥ 0.105). CONCLUSION: Pediatric reference databases for optic disc parameters and ranges of normality for interocular symmetry provide key diagnostic support in diseases that affect the optic nerve. [ABSTRACT FROM AUTHOR]

Competing Interests: There are no conflicts of interest.

AIM: To investigate interocular differences in macular ganglion cell complex(mGCC)thickness in normal healthy subjects, and to determine cutoffs for interocular differences in mGCC thickness in normal healthy subjects.METHODS: This was a cross-sectional study. mGCC thickness were measured in 236 healthy volunteers(472 eyes)using optical coherence tomography(OCT). The differences and the relationships of mGCC thickness between right and left eyes were analyzed. RESULTS: For the right eyes, the mean average mGCC thickness was 91.99±6.61μm, and for the left, 91.75±9.93μm, with no significant difference. The mean mGCC thickness among superior and inferior in the right eye were 92.32±6.66μm and 91.27±8.87μm, respectively. The mean mGCC thickness among superior and inferior in the left eye were 92.05±6.55 and 91.51±6.76μm, respectively. It is comparable between the two eyes at different area. The P2.5 and P97.5 percentiles of interocular difference for mean average mGCC thickness were -4.82μm and 4.36μm, for superior mGCC thickness, -5.79μm and 6.42μm, and for inferior mGCC thickness, -7.21μm and 6.28μm. There was a strong correlation in the corresponding area between the right and left eyes for the mGCC thickness.CONCLUSION: mGCC thickness shows significant interocular symmetry in normal subjects. Interocular difference exceeding the normal limits should be considered significantly asymmetrical, and may be indicative of glaucoma.

This study focuses on the interocular comparison of choroidal parameters in diabetic patients with diabetic retinopathy (DR) with and without diabetic macular edema (DME), as well as in patients with unilateral DME (present in only one eye). The aim of this study was to determine the symmetry in order to obtain better insights into the pathophysiology of diabetic choroidopathy. This retrospective single-center cross-sectional study included 170 eyes from 85 patients (61 with DR and 24 controls), divided into subgroups depending on the presence of DME. The patients underwent fluorescein angiography and spectral domain optical coherence tomography examination, and the analysis included various choroidal parameters: choroidal thickness, volume, and the choroidal vascularity index (CVI). In terms of the choroidal thickness, one eye of a patient with DR, regardless of the presence, absence, or unilaterality of DME, may be treated as representative for that patient. CVI proved symmetrical for controls and patients with DR without DME. However, there was some asymmetry of CVI in patients with bilateral or unilateral DME. There was no straightforward relationship between choroidopathy and DME. Other mechanisms were also involved in the pathogenesis.

AIM: To observe the interocular symmetry of primary angle-closure suspects'(PACS)parameters using IOL Master.METHODS: A cross-sectional observational study. Totally 112 eyes from 56 subjects were enrolled to detect the difference of the bilateral axial length(AL), anterior chamber depth(ACD)and white to white distance(WTW), and to evaluate the correlation between the interocular differences of △AL, △ACD and △WTW and age, gender. RESULTS: All the parameters were analyzed by paired-samples t test and there were no significant interocular difference(P>0.05). There was no relation of ΔAL,ΔACD and ΔWTW with age and gender. CONCLUSION: Interocular symmetry of parameters by IOL Master was observed in PACS, and we found that the symmetry would not be altered when the age and gender had changed.

BACKGROUND:The 13-lined ground squirrel (13-LGS) possesses a cone-dominant retina that is highly amenable to non-invasive high-resolution retinal imaging. The ability for longitudinal assessment of a cone-dominant photoreceptor mosaic with an adaptive optics scanning light ophthalmoscope (AOSLO) has positioned the 13-LGS to become an accessible model for vision research. Here, we examine the interocular symmetry, repeatability, and reliability of cone density measurements in the 13-LGS. METHODS:Thirteen 13-LGS (18 eyes) were imaged along the vertical meridian with a custom AOSLO. Regions of interest were selected superior and inferior to the optic nerve head, including the cone-rich visual streak. Non-confocal split-detection was used to capture images of the cone mosaic. Five masked observers each manually identified photoreceptors for 26 images three times and corrected an algorithm's cell identification outputs for all 214 images three times. Intraobserver repeatability and interobserver reliability of cone density were characterized using data collected from all five observers, while interocular symmetry was assessed in five animals using the average values of all observers. The distribution of image quality for all images in this study was assessed with open-sourced software. RESULTS:Manual identification was less repeatable than semi-automated correction for four of the five observers. Excellent repeatability was seen from all observers (ICC = 0.997-0.999), and there was good agreement between repeat cell identification corrections in all five observers (range: 9.43-25.71 cells/degree2). Reliability of cell identification was significantly different in two of the five observers, and worst in images taken from hibernating 13-LGS. Interocular symmetry of cone density was seen in the five 13-LGS assessed. Image quality was variable between blur- and pixel intensity-based metrics. CONCLUSIONS:Interocular symmetry with repeatable cone density measurements suggest that the 13-LGS is well-suited for longitudinal examination of the cone mosaic using split-detection AOSLO. Differences in reliability highlight the importance of observer training and automation of AOSLO cell detection. Cone density measurements from hibernating 13-LGS are not repeatable. Additional studies are warranted to assess other metrics of cone health to detect deviations from normal 13-LGS in future models of cone disorder in this species.

Purpose: To determine interocular differences in the retinal nerve fiber layer (RNFL) and optic nerve head (ONH) parameters in a pediatric population using Cirrus high-definition optical coherence tomography (HD-OCT). Methods: Seventy normal Indian children aged 5–17 years presenting to the Pediatric Clinic were included in this observational cross-sectional study. All subjects underwent a comprehensive ophthalmologic examination and an evaluation of the RNFL and ONH by Cirrus HD-OCT. Differences between the right and left eyes were calculated and values were compared by means of a paired t-test. Subjects were also divided into two groups based on age (under or over 10 years of age). Interocular differences in RNFL and ONH parameters together with sex and age variations for these differences were determined. Results: The mean age of studied pediatric population was 11.83 ± 3.3 years (range 5–17). Average RNFL thickness was 94.46 ± 8.7 μm (± SD) (range 77–111). Differences in the average RNFL between right and left eyes were not statistically significant (P = 0.060). Superior quadrant RNFL was thicker in the left eye and temporal quadrant was thicker in the right eye. Among ONH parameters, there were no statistically significant differences in any parameters, except vertical cup-disc (CD) ratio which was significant (P = 0.007). The 2.5%–97.5% limits of asymmetry were 9 μm for average RNFL, 0.14 for average CD ratio, and 0.22 for vertical CD ratio. Mean interocular RNFL thickness differences in superior, superior nasal, and temporal superior quadrants were 10.61 (P < 0.001), 12.57 (P < 0.001), and 4.46 (P = 0.002) μm, respectively. Interocular nerve fiber layer thickness differences were not significantly correlated with sex, while only significant differences with age were observed in 12 clock hour sector analysis, mainly in nasal inferior and inferior quadrant. Conclusions: We report the degree of interocular symmetry of RNFL and ONH parameters measured by Cirrus HD-OCT in a healthy pediatric population. The normal interocular RNFL asymmetry should not exceed 9 μm and vertical CD ratio beyond 0.22 should be considered for further investigations. The physiologic asymmetry provided by this study may assist in identifying changes in RNFL thickness and ONH parameters in pediatric glaucoma and ONH disorders.

Purpose: To determine the limits of normal interocular symmetry and the repeatability of central corneal thickness (CCT) and endothelial cell morphology and density., Methods: Two hundred and seventy-eight subjects (age: 10.9-80.7 years) with healthy eyes were studied. CCT as well as endothelial cell morphology and density were measured by non-contact specular microscopy. Three measurements were obtained per eye per participant. Upper and lower tolerance limits of normal interocular symmetry were defined as the 2.5th and 97.5th percentiles of the interocular differences in CCT, endothelial cell density (CECD), coefficient of variation (CoV), hexagonality, and cell size. Repeatability was determined using the intraclass coefficient correlation (ICC), the coefficient of variation (CV), and the test-retest variability standard deviation (TRTSD)., Results: The mean interocular differences were -1.05 ± 17.5 µm ( p = .32) for CCT and 0.5 ± 90.8 cells/mm 2 ( p = .76) for CECD. The 2.5th and 97.5th percentiles of the interocular differences were -13.9 and 15.4 µm for CCT and -177.4 cells/mm 2 to 182.0 cells/mm 2 for CECD. Only interocular difference in CoV correlated weakly with age ( r = -0.22, P < .001). ICCs were 0.93 (95% CI: 0.89-0.96, P < .001) for CCT and 0.95 (0.94-0.96, P < .001) for CECD. CV and TRTSD were 1.2% ± 5.3% and 4.4 ± 3.4 µm for CCT and 2.4% ± 3.9% and 17.7 ± 7.7 cells/mm 2 for CECD, respectively., Conclusions: CCT and CECD showed good repeatability and interocular symmetry in normal Congolese subjects. Absolute interocular differences in CCT and CECD exceeding 15.5 µm and 182 cells/mm 2 , respectively, should be considered suspicious and investigated. When comparing two intrasession measurements from the same eye, a difference of approximately 4.5 µm in CCT and 18 cells/mm 2 or greater may be considered statistically significant.

Unilateral corneal indices and topography maps are routinely used in practice, however, although there is consensus that fellow-eye asymmetry can be clinically significant, symmetry studies are limited to local curvature and single-point thickness or elevation measures. To improve our current practices, there is a need to devise algorithms for generating symmetry colormaps, study and categorize their patterns, and develop reference ranges for new global discriminative indices for identifying abnormal corneas. In this work, we test the feasibility of using the fellow eye as the reference surface for studying elevation symmetry throughout the entire corneal surface using 9230 raw Pentacam files from a population-based cohort of 4613 middle-aged adults. The 140 × 140 matrix of anterior elevation data in these files were handled with Python to subtract matrices, create color-coded maps, and engineer features for machine learning. The most common pattern was a monochrome circle ("flat") denoting excellent mirror symmetry. Other discernible patterns were named "tilt", "cone", and "four-leaf". Clustering was done with different combinations of features and various algorithms using Waikato Environment for Knowledge Analysis (WEKA). Our proposed approach can identify cases that may appear normal in each eye individually but need further testing. This work will be enhanced by including data of posterior elevation, thickness, and common diagnostic indices.

Background: We aimed to study the bilateral choroidal thickness (CT) symmetry and difference in uncomplicated pachychoroid subjects using wide-field swept-source optical coherence tomography (SS-OCT)., Methods: All subjects underwent a wide-field 16-mm one-line scan using SS-OCT. Bilateral CT was measured at, and compared among, the following 12 points: three points at 900-µm intervals from the nasal optic disc margin (nasal peripapillary area), one point at the subfovea, six points at 900-µm intervals from the fovea to the nasal and temporal areas (macular area), and two peripheral points 5400 and 8100 µm from the fovea (peripheral area)., Results: There were no statistically significant differences in CT between the right and left eyes in any area (all p > 0.05); they all showed significant positive correlations (all p < 0.01). However, the correlation coefficients (ρ) were smaller for the nasal peripapillary and peripheral areas compared to the macular area., Conclusions: The CTs in each region were bilaterally symmetrical in subjects with uncomplicated pachychoroid. However, interocular difference in CT increased from the center to the periphery, indicating that the anatomical variation of the nasal peripapillary and peripheral choroid was greater than that of the macula.

Purpose: To determine the interocular symmetry of foveal cone topography in achromatopsia (ACHM) using non-confocal split-detection adaptive optics scanning light ophthalmoscopy (AOSLO). Methods: Split-detector AOSLO images of the foveal cone mosaic were acquired from both eyes of 26 subjects (mean age 24.3 years; range 8–44 years, 14 females) with genetically confirmed CNGA3- or CNGB3-associated ACHM. Cones were identified within a manually delineated rod-free zone. Peak cone density (PCD) was determined using an 80 × 80 μm sampling window within the rod-free zone. The mean and standard deviation (SD) of inter-cell distance (ICD) were calculated to derive the coefficient of variation (CV). Cone density difference maps were generated to compare cone topography between eyes. Results: PCD (mean ± SD) was 17,530 ± 9,614 cones/mm2 and 17,638 ± 9,753 cones/mm2 for right and left eyes, respectively (p =.677, Wilcoxon test). The mean (± SD) for ICD was 9.05 ± 2.55 µm and 9.24 ± 2.55 µm for right and left eyes, respectively (p =.410, paired t-test). The mean (± SD) for CV of ICD was 0.16 ± 0.03 µm and 0.16 ± 0.04 µm for right and left eyes, respectively (p =.562, paired t-test). Cone density maps demonstrated that cone topography of the ACHM fovea is non-uniform with local variations in cone density between eyes. Conclusions: These results demonstrate the interocular symmetry of the foveal cone mosaic (both density and packing) in ACHM. As cone topography can differ between eyes of a subject, PCD does not completely describe the foveal cone mosaic in ACHM. Nonetheless, these findings are of value in longitudinal monitoring of patients during treatment trials and further suggest that both eyes of a given subject may have similar therapeutic potential and non-study eye can be used as a control. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper was to study the bilateral choroidal thickness (CT) symmetry and differences in healthy individuals using wide-field swept-source optical coherence tomography (SS-OCT)., Methods: All participants underwent a wide-field 16-mm 1-line scan using SS-OCT. CTs were measured at the following 12 points: 3 points at 900 µm, 1800 µm, and 2700 µm away from the nasal optic disc margin (nasal peripapillary area), 1 point at the subfovea, 6 points at 900 µm, 1800 µm, and 2700 µm away from the subfovea to the nasal and temporal areas (macular area), and 2 peripheral points at 2700 and 5400 µm from temporal point 3 (peripheral area). Bilateral CTs were measured; their correlations and differences in the corresponding regions were analyzed., Results: There were no statistically significant differences in CTs between the right and left eyes in all corresponding areas (all P > 0.05); they all showed significant positive correlation coefficients (r) (all P < 0.001). However, the nasal peripapillary and peripheral areas had relatively low correlation coefficients, compared to the macular areas. In addition, the bilateral CT differences were 32.60 ± 25.80 µm in the macular area, 40.67 ± 30.58 µm in the nasal peripapillary area, and 56.03 ± 45.73 µm in the peripheral area (all P < 0.001)., Conclusions: Overall, the CTs of each region were bilaterally symmetrical. However, the differences in CTs increased from the center to the periphery, which indicated that the anatomic variation of the nasal peripapillary and peripheral choroid was greater than that of the macula.

To report interocular differences in macular ganglion cell complex (mGCC) thickness in young Chinese subjects using RTVue-100 optical coherence tomography (OCT).This was an observational, cross-sectional study. The mGCC thickness was measured in 158young Chinese subjects using RTVue-100 OCT. The normal ranges of the interocular differences were determined as falling between the 2.5th and 97.5th percentiles. Right and left eyes were compared using a paired t test. Pearson correlation analysis was performed to assess the relationships between mGCC thickness and other potential factors. The relationships between the interocular difference in the average mGCC thickness and the potential factors were evaluated by univariate and multivariate linear regression analysis.The mean interocular difference in the average, superior, and inferior mGCC thickness were 0.19 ± 2.69 μm, 0.22 ±3.14 μm, and 0.25±3.34 μm, respectively, which were not statistically significant. The 2.5th and 97.5th percentiles of interocular difference for mean average mGCC thickness were -4.82μm and 4.38μm, for superior mGCC thickness, -6.67 μm and 7.04 μm, and for inferior mGCC thickness, -6.75 μm and 6.27 μm. There was a strong correlation between the right and left eyes for all the studied parameters, including spherical equivalent (SE) and axial length (AL). Interocular difference in SE (p = 0.007) were independently correlated with the interocular difference in average mGCC thickness.There was no significant relative interocular difference in mGCC thickness in young Chinese subjects. Interocular difference exceeding the normal limits should be considered significantly asymmetrical, and suggestive of pathology.

To determine normal values, repeatability, and interocular symmetry of optic nerve head measurements, three spectral-domain optical coherence tomography (SD-OCT) scans were obtained from 128 healthy Turkish children aged 5-17 years consecutively and prospectively. The mean disc area, rim area, cup volume, cup to disc area ratio, and vertical and horizontal cup to disc ratios were 2.30 ± 0.42 mm2, 1.84 ± 0.45 mm2, 0.09 ± 0.10 mm3, 0.20 ± 0.13, 0.37 ± 0.17, and 0.45 ± 0.20, respectively. The intraclass correlation coefficients were >0.9 for repeatability and >0.75 for interocular correlation. Interocular differences were not statistically significant (p > 0.05). Normal paediatric SD-OCT measurements of the optic nerve head are presented, which showed excellent repeatability and no interocular difference. [ABSTRACT FROM AUTHOR]

Purpose: To test the hypothesis that foveal cone topography is symmetrical between contralateral eyes., Methods: We used adaptive optics scanning light ophthalmoscopy to acquire images of the foveal cone mosaic in each eye of 58 subjects with normal vision (35 female, 23 male). Cones were semiautomatically identified over a 300 × 300-µm foveal area. From these cone coordinates, maps of cone density were derived, and we extracted estimates of peak cone density from each map. Mosaic regularity was assessed using Voronoi cell area regularity (VCAR). Average roundness and average area of the 70%, 75%, 80%, 85%, and 90% of peak density isodensity contours were evaluated., Results: The average peak cone density for right eyes was 180,286 cones/mm2 (n = 49) and for left eyes was 182,397 cones/mm2 (n = 45), with a mean absolute difference of 6363 cones/mm2 (n = 43). Peak density, cone spacing, VCAR, and average area within the isodensity contours of fellow eyes were not significantly different (P = 0.60, P = 0.83, P = 0.30, and P = 0.39, respectively). However, the average roundness of the isodensity contours was 2% more circular in the right eyes than in the left eyes (P = 0.02)., Conclusions: There is interocular symmetry of peak foveal cone density, mosaic regularity, and area encompassing the most densely packed cells in subjects with normal vision. The origin and significance of the observed interocular difference in average roundness of the isodensity contours are unclear.

This study focuses on the interocular comparison of choroidal parameters in diabetic patients with diabetic retinopathy (DR) with and without diabetic macular edema (DME), as well as in patients with unilateral DME (present in only one eye). The aim of this study was to determine the symmetry in order to obtain better insights into the pathophysiology of diabetic choroidopathy. This retrospective single-center cross-sectional study included 170 eyes from 85 patients (61 with DR and 24 controls), divided into subgroups depending on the presence of DME. The patients underwent fluorescein angiography and spectral domain optical coherence tomography examination, and the analysis included various choroidal parameters: choroidal thickness, volume, and the choroidal vascularity index (CVI). In terms of the choroidal thickness, one eye of a patient with DR, regardless of the presence, absence, or unilaterality of DME, may be treated as representative for that patient. CVI proved symmetrical for controls and patients with DR without DME. However, there was some asymmetry of CVI in patients with bilateral or unilateral DME. There was no straightforward relationship between choroidopathy and DME. Other mechanisms were also involved in the pathogenesis. [ABSTRACT FROM AUTHOR]

Objective. To report interocular differences in choroidal thickness in children using spectral domain optical coherence tomography (SD-OCT) and correlate findings with biometric data. Methods. This observational cross-sectional study included 91 (182 eyes) healthy children aged 6 to 17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, high definition macular scans were performed using SD-OCT. Two observers manually measured the choroidal thickness at the foveal center and at 1500 µm nasally, temporally, inferiorly, and superiorly. Interocular differences were computed; correlations with age, gender, refractive error, and axial length were performed. Results. Mean age was 10.40 ± 3.17 years; mean axial length and refractive error values were similar between fellow eyes. There was excellent correlation between the two observers’ measurements. No significant interocular differences were observed at any location. There was only a trend for right eyes to have higher values in all thicknesses, except the superior thickness. Most of the choroidal thickness measurements correlated positively with spherical equivalent but not with axial length, age, or gender. Conclusion. Choroidal thickness measurements in children as performed using SD-OCT revealed a high level of interobserver agreement and consistent interocular symmetry. Values correlated positively with spherical equivalent refraction.