[Show abstract] [Hide abstract]
ABSTRACT: To evaluate the effects of signal strength, age, sex, optic disc size, and axial length on the normal optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular measurements with spectral domain optical coherence tomography (SD-OCT).
In an observational, cross-sectional study, 119 eyes of 60 normal subjects of Indian origin underwent ONH, RNFL, and macular imaging with SD-OCT during the same visit. Linear mixed-modeling methods were used to evaluate the effects of signal strength, age, sex, optic disc area, and axial length on ONH, RNFL, and macular measurements.
ONH rim measurements increased and cup measurements decreased with increasing signal strengths. For a 10-unit increase in signal strength, total rim area increased by a mean of 0.1 mm(2). ONH measurements also increased with increasing optic disc size. Rim measurements decreased and cup measurements increased with increasing axial length. None of the predictors influenced RNFL measurements. Macular inner retinal thickness decreased by a mean of 1.7 μm and macular full retinal thickness decreased by an average of 3.4 μm for every decade's increase in age. Sex did not influence any of the measurements.
Signal strength, optic disc size, and axial length had a significant effect on ONH measurements, whereas age had a significant effect on macular measurements. None of the predictors evaluated influenced the RNFL measurements. These predictors should be considered when evaluating change in the structural measurements in glaucoma over time.
Investigative ophthalmology & visual science 11/2010; 52(2):1103-10. · 3.43 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: To determine (1) repeatability of central corneal thickness (CCT) measurements by spectral domain optical coherence tomography (RTVue; Optovue, Inc, Fremont, CA) and (2) agreement between CCT measurements by RTVue and those by ultrasonic pachymetry, Orbscan, and anterior segment optical coherence tomography (ASOCT).
In a prospective observational study, 2 cohorts of normal subjects were recruited. In the first cohort (51 subjects), 5 measurements of CCT were obtained by RTVue during the same visit to determine the repeatability. In the second cohort (65 subjects), CCT measurements were obtained by RTVue, ultrasonic pachymetry, Orbscan, and ASOCT during the same visit to determine the agreement among these instruments. Repeatability was assessed by intraclass correlation coefficient (ICC), within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation. Agreement was assessed by ICC and Bland and Altman plots.
Repeatability of CCT measurements by RTVue as assessed by ICC, within-subject standard deviation, coefficient of repeatability, and within-subject coefficient of variation was 0.99 (0.99-0.99), 2.2 (1.9-2.5), 4.2 μm (3.6-4.8), and 0.4% (0.3-0.5), respectively. The average CCT by RTVue (529 μm) was comparable to that by ultrasonic pachymetry (539 μm; P = 0.15), Orbscan (536 μm; P = 0.54), and ASOCT (526 μm; P = 0.77). The 95% limits of agreement on Bland and Altman plots ranged from 20 μm (between RTVue and ASOCT) to 33 μm (between RTVue and Orbscan).
CCT measurements by RTVue have an excellent repeatability. Although CCT measurements by RTVue are comparable to that by ultrasonic pachymetry, Orbscan, and ASOCT, the difference between instruments can be significant depending on the clinical situation considered.
Cornea 09/2010; 30(2):121-6. · 1.75 Impact Factor
Investigative Ophthalmology & Visual Science 01/2010; · 3.44 Impact Factor