The axial length affected the average RNFL thickness, and myopia affected the RNFL thickness distribution. High myopes are likely to exhibit different RNFL distribution patterns. Since ocular magnification significantly affects the RNFL measurement in such patients, it should be considered in diagnosing glaucoma.

PURPOSE. To determine the anatomic variations in the peripapillary retinal nerve fiber layer (RNFL) thickness distribution and the relationship between these anatomic variations and other ocular variables. METHODS. A complete ophthalmic examination, including measurement of visual acuity, refraction, and axial length, was performed on 269 subjects with no ophthalmic abnormalities. Further, fundus photographs and optic disc cube scans of the subjects' eyes were obtained with a fundus camera and spectral domain OCT (Cirrus HD-OCT; Carl Zeiss Meditec, Inc., Dubin, CA), respectively. The distance between the foveola and the center of the optic nerve head was measured. The correlations of the angles of the peaks in the RNFL thickness profile with the axial length, spherical equivalent of refractive error (SE), and distance between the foveola and optic disc center were analyzed by simple linear regression. RESULTS. Considerable interindividual variations were found in the angles of the peaks in the RNFL thickness profile. Further, the angles in the eyes in each individual showed significant differences. The angles of the superior and inferior first peak correlated significantly with the SE, axial length, and distance between the foveola and optic disc center. CONCLUSIONS. Subjects with increased distance between the foveola and optic disc center are likely to have a temporal shift in peak RNFL thickness. RNFL profiles with horizontally deviated peak RNFL thickness differ considerably from the normative data provided with the HD-OCT system. The variations in RNFL thickness profiles should be taken into account.

PurposeTo evaluate the changes of refractive astigmatism after horizontal rectus muscle surgery in intermittent exotropic children.MethodsSixty-nine exotropic patients were retrospectively reviewed. Of those, 35 patients received unilateral lateral rectus recession (BLR group, 35 eyes) and 34 patients received unilateral lateral rectus recession and medial rectus resection (R&R group, 34 eyes). Non-cycloplegic refractions were measured until 6 months postoperatively. Spherical equivalent (SE), J0 and J45 using power vectors were calculated to determine and compare the changes of refractive astigmatism and axis in both groups.ResultsSE significantly decreased after surgery for the first week and did not changed thereafter in both groups (p = 0.000 and p = 0.018, respectively). In BLR group, J0 showed significant changes at the first week and 1 month after surgery (p = 0.005 and p = 0.016, respectively), but in R&R group, J0 changed significantly between 1 week and 3 months postoperatively (p = 0.023 and p = 0.016, respectively). J45 did not change significantly as time passed in both groups (all p > 0.05). There was no statistically significant difference in the magnitude of changes in SE, J0 and J45 between the two groups after the 6-month follow-up (p = 0.500, p = 0.244 and p = 0.202, respectively).ConclusionsHorizontal rectus muscle surgery in intermittent exotropic children tends to induce a statistically significant change in astigmatism in the with-the-rule direction and myopic shift in SE. This astigmatism change seems to occur within the first 3 months after surgery. Thus, astigmatism induced by surgery should be checked and corrected at least 3 months after horizontal strabismus surgery.

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To assess anterior scleral canal opening (ASCO) offset relative to Bruch's membrane opening (BMO) (ASCO/BMO offset) so as to determine neural canal direction, obliqueness, and minimum crosssectional area (NCMCA) in 362 healthy eyes. DESIGN: Cross-sectional study. METHODS: After optical coherence tomography optic nerve head and retinal nerve fiber layer thickness (RNFLT) imaging, BMO and ASCO were manually segmented. Planes, centroids, size, and shape were calculated. Neural canal direction was defined by projecting the neural canal axis vector (connecting BMO and ASCO centroids) onto the BMO plane. Neural canal obliqueness was defined by the angle between the neural canal axis and the BMO plane perpendicular vector. NCMCA was defined by projecting BMO and ASCO points onto a neural canal axis perpendicular plane and measuring the area of overlap. The angular distance between superior and inferior peak RNFLT was measured, and correlations between RFNLT, BMO, ASCO, ASCO/ BMO offset, and NCMCA were assessed. RESULTS: Mean (SD) NCMCA was significantly smaller than either the BMO or ASCO area (1.33 (0.42), 1.82 (0.38), 2.22 (0.43) mm 2 , respectively), and most closely correlated to RNFLT (P < .001, R 2 [ 0.158). Neural canal direction was most commonly superior-nasal (55%). Mean neural canal obliqueness was 39.4 8 (17.3 8). The angular distance between superior and inferior peak RNFLT correlated to neural canal direction (P £ .008, R 2 [ 0.093). CONCLUSIONS: ASCO/BMO offset underlies neural canal direction, obliqueness, and NCMCA. RNFLT is more strongly correlated to NCMCA than to BMO or ASCO, and its peripapillary distribution is influenced by neural canal direction.

On the basis of the data obtained here from normal individuals, a corrected symmetry value of <0.77 might indicate the presence of pathologic conditions affecting the RNFL. Interocular RNFL thickness symmetry was influenced more heavily by interocular superotemporal vessel location than by anisometropia.

The RNFL thickness is likely to be overestimated in children <15 years old. Additionally, an RNFL thickness increase was observed in children <15 years old. Thus, ocular magnification and RNFL thickness increase should be considered when assessing RNFL thickness in patients <15 years old.

Distance stereoacuity reaches adult levels at approximately 5 years of age. These data of the age-related normal values could represent a reference frame for the comparison of data obtained for clinical populations.