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M. Skaf, A.B. Bernardes, L.A. S. Melo, Jr., F. Tognin, R.A. Costa, J.C. Castro, J.A. Cardillo; OCT Assessment of the Retinal Nerve Fiber Layer Thickness of the Peripapillary Area in Normal and Glaucomatous Eyes . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3380.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate and compare the RNFL thickness of the peripapillary region up to a distance of 1400 µm from the disc margin of normal and glaucomatous eyes.
After a complete ophthalmologic examination, 20 normal volunteers, 20 early glaucomatous eyes (visual field defects at the 24–2 Humphrey SITA test with MD index better than – 6.00 dB) and 4 moderate glaucomatous eyes (MD between – 6.00 and > –12 dB) were selected. One eye of each patient was studied. A sequence of 24 circular scans with 8 different radii (3 circular scans per radius) around the optic disc was performed. For all groups, the first circular scan was adjusted to the size of the optic disc and 3 scans were performed at this radius and at every 200–µm radius increment up to a distance of 1400 µm from the disc margin. From the RNFL thickness analyzes protocol (single eye) the overall mean and the average thickness of each hour for each scan were used for statistical analysis. For the glaucomatous group the correlations between RNFL values and MD values of the visual field were analyzed.
The largest differences of RNFL thickness between normal and glaucomatous eyes were found close to disc margin (0 µm) at every clock hour (P < 0.05), at the inferior area up to 800 µm, and at the inferotemporal area (7 o’clock for right eyes and 5 o’clock for left eyes) at every distance from the disc margin (P < 0.001). The highest correlations between RNFL thickness values and MD visual field index were found for overall thickness at 0 µm (r = 0.81), 200 µm (r = 0.83), 400 µm (r = 0.83), and 600 µm (r = 0.83) distance from disc margin, and for inferior area (6 o’clock) at 200 µm (r = 0.81) and 1000 µm (r =0.81) distance.
This sequential OCT–RNFL thickness analysis at regular distances from the disc margin in normal and glaucomatous eyes mapped the RNFL thickness of the peripapillary region and demonstrated that the area closer to disc margin, inferior area and specially inferotemporal area are the most sensitive areas to detect glaucomatous damage. The best correlation between RNFL thickness and MD was found for overall thickness values of scans obtained closer to disc margin up to a distance of 600 µm.
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