Reproducibility of Nerve Fiber Layer Thickness Measurements Using Optical Coherence Tomography

Abstract

Purpose-Optical coherence tomography (OCT) is a new technology that uses near-infrared light in an interferometer to produce approximately 10-μm resolution cross-sectional images of the tissue of interest. The authors performed repeated quantitative assessment of nerve fiber layer thickness in individuals with normal and glaucomatous eyes, and they evaluated the reproducibility of these measurements. Methods-The authors studied 21 eyes of 21 subjects by OCT. Each subject underwent five repetitions of a series of scans on five separate occasions within a 1-month period. Each series consisted of three circular scans around the optic nerve head (diameters, 2.9, 3.4, and 4.5 mm). Each series was performed separately using internal (fixation with same eye being studied) and external (fixation with contralateral eye) fixation techniques. The eye studied and the sequence of testing were assigned randomly.Results-Internal fixation (IF), in general, provides a slightly higher degree of reproducibility than external fixation (EF). Reproducibility was better in a given eye on a given visit than from visit to visit. Reproducibility as measured by intraclass correlation coefficients were as follows: circle diameter (CD), 2. Conclusions-Nerve fiber layer thickness can be reproducibly measured using OCT. Internal is superior to external fixation; each circle diameter tested provides adequate reproducibility.Optical coherence tomography (OCT) is a new technology that allows cross-sectional imaging of the eye using light. This technology is noncontact and noninvasive and may have use in diagnosing and managing retinal disease and glaucoma. We previously reported on the quantification of nerve fiber layer (NFL) and retinal thickness using OCT; however, for this technology to provide meaningful data, measurements must be reproducible.The goal of this study is to determine the reproducibility of measurements of NFL and retinal thickness made by OCT. We also sought to evaluate the optimal circle diameter for OCT NFL

Objective analysis of retinal damage in HIV-positive patients in the HAART era using OCT

“…However, we found that the temporal RNFL thickness had a tendency to be thinner than the nasal quadrant. Similar to our results, observations between these two retinal areas that reached statistical significance, however, were described in works by Varma 32 and later reports by Schuman 23 and are also supported by histologic data. 33 We emphasize that there is a scarcity of published work on normal RNFL thickness using third-generation OCT. Because of its improved resolution, the anterior and posterior borders of RNFL are apt to be better defined.…”

“…Our results of overall RNFL thickness and thickness measurements in particular retinal areas using the new generation OCT are consistent with previous reports using a default scan diameter of 3.4 mm from the center of the optic nerve head 23,[27][28][29] (RM Vessani, Retinal nerve fiber layer thickness measured by OCT3 and central corneal thickness in ocular hypertensive patients, ARVO 2004, paper #3407). The RNFL was thickest in the superior and inferior retinal areas and thinner in the temporal and nasal ones, which is in agreement with other studies.…”

“…19,21,22 OCT, which uses short coherence length interferometer, has a fine resolution (cca 10 μm) and reflects the histologic characteristics of the tissue. Because OCT is based on cross-sectional images of the retina, the instrument measures the retinal NFL directly, has no need for a reference plane, and is known to be unaffected by the refractive status, axial length of the subject, sclerosis of the lens, 23 or pupillary dilation. 24,25 The only limitations of OCT imaging are the uncertainty of the assumed group refractive index of tissue, the effect of eye movements during the B-scan location, and the interface detection artifacts.…”

Optical coherence tomography measurement of macular and nerve fiber layer thickness in normal and glaucomatous human eyes

“…Detailed descriptions of the principles of OCT have already been published; a summary follows. [11][12][13][14][15][16][17][18][19][20][21][22][23] OCT is based on the principles of low coherence interferometry. By directing a low coherence light beam, which is analogous to a series of short pulses of light, onto a partially reflective mirror, two beams are created: reference and measurement beam.…”

Cup-to-disc ratio: agreement between slit-lamp indirect ophthalmoscopic estimation and stratus optical coherence tomography measurement

“…7,8,[12][13][14] The reproducibility of ONH measurements using the Stratus OCT (Carl Zeiss Meditec, Dublin, CA, USA) was reported recently to be sufficient, especially regarding the cup-to-disc ratios (CDRs). 15 Although OCT may give objective measurement with less variation than biomicroscopy, this in itself does not mean that it will be more accurate in estimating the actual disc measurements.…”