Symmetry of retinal parameters measured by spectral-domain OCT in normal young adults.

PURPOSE: To determine interocular differences in retinal parameters in a population of young adults using spectral-domain optical coherence tomography. METHODS: In the Sydney Adolescent Vascular Eye Study, young adults aged 16 to 19 years received a standardized eye examination encompassing retinal photography, spectral-domain optical coherence tomography (Cirrus HD-OCT; Carl Zeiss Meditec, Dublin, CA) and best-corrected visual acuity. Interocular differences in retinal nerve fiber layer (RNFL) and macular parameters together with sex and ethnic variations for these differences were determined. RESULTS: In the 1500 subjects tested, right eyes had thicker average RNFL than left eyes (0.3 µm, P=0.0074). There were no significant interocular differences in central macular or macular cube average thickness. After adjusting for interocular difference in axial length, right eyes had slightly smaller total macular volume than left eyes (-0.0082 mm, P=0.008). The 2.5% to 97.5% limits of asymmetry were 9.3 µm for average RNFL, 8 µm for average macular thickness, and 0.20 mm for total macular volume. In the outer inferior quadrant, there was a greater macular thickness asymmetry in females than males (-0.7 µm, P=0.037). In the inferior RNFL quadrant (-2.6 µm, P=0.0013) and in the outer inferior macular quadrant (1.6 µm, P=0.0018), white individuals had greater symmetry than East Asians. CONCLUSIONS: In this study, we report the degree of interocular symmetry of RNFL and macular parameters measured by Cirrus HD-OCT in healthy young adults.

Symmetry of optic nerve head parameters measured by the heidelberg retina tomograph 3 in healthy eyes: the Blue Mountains Eye study.

PURPOSE: To assess the symmetry of optic nerve head parameters measured by the Heidelberg Retina Tomograph 3 (HRT 3) between fellow eyes in a normal elderly population. DESIGN: Cross-sectional population-based study. METHODS: Participants of the Blue Mountains Eye Study 10-year follow-up who did not have optic disc disease, including glaucoma, were included. Optic nerve head parameters measured by HRT 3 were compared between fellow eyes. The normal range of interocular asymmetry (larger disc minus smaller disc) was determined by the 2.5th and 97.5th percentiles. RESULTS: A total of 1276 eligible participants had HRT scans of both eyes. HRT measurements in right eyes differed slightly in rim steepness and rim volume from those in left eyes (P < .05). The 2.5th and 97.5th percentile of interocular asymmetry limits were -0.41 and 0.45 for cup-to-disc ratio and -0.19 and 0.22 for cup-to-disc area ratio, respectively. The highest interocular correlation was found in disc area and cup area (r ranged from 0.74-0.76), whereas mean cup depth, cup volume, and retinal nerve fiber layer thickness had the poorest correlation (r ≤ 0.07). Greater optic disc area asymmetry was associated with a larger interocular difference in the other optic nerve head parameters. CONCLUSIONS: There was minimal interocular difference and substantial interocular correlation in optic nerve head parameters measured by HRT 3. Interocular asymmetry greater than 0.2 for cup-to-disc area ratio was considered outside the normal range.

Macular parameters and prematurity: A spectral domain coherence tomography study.

PURPOSE: To investigate the association of premature birth with macular parameters measured by spectral domain coherence tomography (SD-OCT). METHODS: The Sydney Adolescent Vascular and Eye Study performed eye examinations in school students across Sydney between 2009 and 2011. Visual acuity, cycloplegic autorefraction, and optical biometry measurements were recorded. Macular parameters were measured with SD-OCT. Questionnaires previously completed by the participants' parents were used to determine perinatal and medical history. Children with retinal disease or a known history of retinopathy of prematurity were excluded from the analysis. RESULTS: Macular measurements from the right eye of 1,672 participants ages 10-19 years were analyzed. The central subfield in those born at ≤32 weeks' gestational age was significantly thicker than those born at ≥37 weeks' gestational age (266.3 µm vs 251.7 µm, P = 0.0007). The average cube thickness and average outer macular ring thickness were smaller in those born at ≤32 weeks compared with those born at ≥37 weeks (P = 0.03 and 0.02, respectively). Similarly, the cube volume was smaller in the ≤32 weeks' group compared with the ≥37 weeks' group (P = 0.04). No significant differences were found between the 33-36 weeks' group and the ≥37 weeks' group. CONCLUSIONS: In comparison to babies born at term, thicker central maculas and thinner macular outer rings were found in children born <33 weeks gestational age when measured by SD-OCT at ages 10-19 years.

Ethnic differences in macular thickness.

BACKGROUND: To determine ethnic differences in time-domain (Stratus) optical coherence tomography-measured macular thickness in 12-year-old children. DESIGN: Population-based cross-sectional study. PARTICIPANTS: A total of 2367 children from grade 7 (mean age 12.7 ± 0.45 years) examined during the Sydney Myopia Study during 2004-2005. METHODS: Examination included determination of best corrected visual acuity. Autorefraction was performed after cycloplegia. Axial length was measured using non-contact interferometry and OCT was performed using Stratus OCT. Ethnicity was self reported by participants' parents. MAIN OUTCOME MEASURES: Macular thickness. RESULTS: The four largest ethnic groups were Caucasian (n = 1224), East Asian (n = 291), South Asian (n = 107) and Middle Eastern (n = 146). The greatest ethnic differences were found at the central macula, which was significantly thicker in Caucasian compared with East Asian, South Asian and Middle Eastern children (mean differences 9.0 µm, 12.1 µm and 6.5 µm, respectively; all P < 0.0001). The average inner macula was significantly thicker in Caucasian than East Asian and South Asian children (P = 0.005 and P < 0.0001, respectively). The average outer macula was significantly thicker in Caucasian than Middle Eastern and South Asian children (P = 0.03 and P < 0.0001, respectively). CONCLUSION: Macular parameters were found to vary by ethnicity in 12-year-old children. Caucasian children had the thickest macular parameters and South Asian children had the thinnest. The greatest differences were found in the central macula.

Association of birth parameters with OCT measured macular and retinal nerve fiber layer thickness.

PURPOSE: To examine whether birth parameters have associations with macular and retinal nerve fiber layer (RNFL) thickness measurements. METHODS: The Sydney Myopia Study examined secondary school children for ocular conditions, with all eligible year 7 students from 21 high schools invited to participate. Macular and RNFL measurements were acquired from optical coherence tomography (OCT) scans. Birth variables, including birth weight and gestational duration, were obtained from parental questionnaires and health records. Mixed linear models were used in analyses, after adjustment for age, sex, height, axial length, and ethnicity. RESULTS: In children with complete gestational duration data, adequate quality scans of the RNFL and macula were obtained from 1756 and 1698 children, respectively. Children with low birth weight (<2500 g) had a thinner mean RNFL (98.2 µm vs. 103.5 µm; P < 0.0001) and a thicker mean foveal minimum (164.3 µm vs. 158.5 µm; P = 0.004) than did children of normal birth weight (2500-4000 g). With increasing birth weight, average RNFL thickness increased (mixed model coefficient, ß = 2.97 µm/kg; P < 0.0001) and foveal minimum thickness decreased (ß = -2.16 µm/kg; P = 0.008). Children born before 32 weeks' gestation had significantly thicker mean foveal minimum and central macular thickness (205.5 µm vs. 193.4 µm; P = 0.001) measurements than did children born after 37 weeks' gestation. CONCLUSIONS: Low birth weight and prematurity are associated with thickening of the fovea, and decreased birth weight is associated with decreased RNFL thickness, as measured by OCT. These findings suggest that premature birth and low birth weight impair retinal development and may predispose these children to ocular problems later in life.

Retinal thickness in the offspring of diabetic pregnancies.

PURPOSE: To compare macular and peripapillary retinal nerve fiber layer (RNFL) thickness in children from diabetic compared with nondiabetic pregnancy. DESIGN: Cross-sectional study. METHODS: As part of the Sydney Myopia Study, 2367 children from grade 7 (age range 11.1 to 14.4 years) completed detailed ocular examinations during 2004-2005. Examination included determination of best-corrected visual acuity (logarithm of minimal angle of resolution) and autorefraction after cycloplegia. Axial length was measured using noncontact interferometry. Optical coherence tomography (OCT) was performed using Stratus OCT through dilated pupils. Participants and parents completed comprehensive questionnaires including questions on birth parameters and medical history. RESULTS: There were 1741 and 1687 children with adequate-quality RNFL and macular scans respectively, who had complete examination and questionnaire data. There were 57 children from diabetic pregnancies who had both RNFL and macular scans. Children from diabetic pregnancies had significantly thinner inner (264.9 µm vs 270.2 µm, P = .007) and outer (231.9 µm vs 238.6 µm, P = .0001) macular thickness and macular volume (6.75 mm(3) vs 6.92 mm(3), P = .0003) compared with children from nondiabetic pregnancies. However, central macular thickness, foveal minimum thickness, and RNFL parameters were not significantly different between the 2 groups. CONCLUSION: Diabetes during pregnancy is associated with changes in retinal morphology in the offspring. Thinning of the pericentral macular parameters was evident in Stratus OCT scans of children from diabetic pregnancies. These findings suggest the possibility that maternal diabetes impacts on the development of the retina.

Impact of ethnicity on the correlation of retinal parameters with axial length.

PURPOSE: To examine whether the relationship of axial length (AL) to retinal nerve fiber layer (RNFL) and macular parameters measured by optical coherence tomography (OCT) differs according to ethnicity. METHODS: As part of the Sydney Myopia Study, 2353 children from grade 7 (age range, 11.1-14.4 years) completed detailed ocular examinations in the 2004-2005 school year. AL was measured with noncontact interferometry and Stratus OCT was performed (Carl Zeiss Meditec, Jena, Germany). RESULTS: East Asian children displayed larger AL correlations with average RNFL, inferior RNFL, nasal RNFL, outer macula, and macular volume (r = -0.25, -0.36, -0.31, -0.35, and -0.31 respectively; P < 0.001) than did Caucasian children (r = -0.14, -0.20, -0.12, -0.17, and -0.13 respectively; P < 0.001). Positive correlations between the temporal RNFL and AL were found only among East Asian and South Asian children (r = 0.28, P < 0.001; and r = 0.27, P = 0.03, respectively). In Caucasian children, the foveal minimum and central macula correlated significantly with AL (r = 0.11 and r = 0.13, respectively, P ≤ 0.001). CONCLUSIONS: Retinal parameters measured by OCT correlated with AL, and the extent of this correlation varied by ethnicity. It may therefore be that ethnicity should be considered when interpreting OCT scans on individuals with AL outside the usual range.