Repeatability of quantitative measurements of retinal layers with SD-OCT and agreement between vertical and horizontal scan protocols in healthy eyes

Abstract

Purpose To evaluate the repeatability of the new spectral domain optical coherence tomography (HOCT-1F), and also to evaluate the agreement between vertical and horizontal scan protocols. In addition, we also evaluated the relation between the repeatability and age. Methods Three consecutive measurements of the inner limiting membrane–retinal pigment epithelium (ILM-RPE), inner limiting membrane–inner plexiform layer (ILM-IPL) from macular horizontal and vertical scans, and inner limiting membrane–retinal nerve fiber layer (ILM-RNFL) from optic disc horizontal scan. 159 subjects were included in the analysis. The within subject standard deviation (Sw) and the repeatability limits (R limit ) are used to represent the repeatability of the parameters for the different sectors. Results The Sw for the ILM-RPE thickness was less than 3.5 μm for each sector and scan direction. The Sw values varied within the sectors and scan modes, with horizontal scan modes resulting in better values for the horizontal sectors, and vice versa. The Sw for the GCL-IPL thickness was less than 2 μm, and was similar between the vertical and horizontal scan modes for each sector map. For the optic disc scan, the Sw was not symmetric along the clock-hour map sectors, the largest Sw values were seen in the vertical sectors (8.6 μm). The mean difference between the vertical and horizontal scans was less than 2 μm for each retinal thickness sector map. Significant but weak correlation between the Sw and the subject’s age was seen in both macular and optic disc scans. Conclusions The repeatability of the HOCT-1F to measure the ILM-RPE-, ILM-IPL- and ILM-RNFL-thickness is good. The repeatability of the ILM-RPE thickness is dependent on the scan direction, which should be taken into account when calculating retinal thickness. There is a weak correlation between the repeatability and the subject’s age.

<p>Central Macular Thickness in a Healthy Mexican Population Using Huvitz Optical Coherence Tomography</p>

“…18 For the HOCT-1F, the intra device repeatability of the macular thickness measurement has been shown to be good, although dependent of the direction of the scan (ie, horizontal vs vertical scan). 21 Macular thickness findings reported in other studies are similar to our data (Table 5), we also found that men have a greater macular thickness than women and the temporal macular area has thinner values. A limitation of this study was that the majority (68.7%) of the individuals were • Men had greater retinal thickness in all inner areas (P<0.001)…”

“…The current study obtained CST values from a healthy Mexican population using the HOCT-1F unit, which was recently launched on the market and has undergone limited evaluations. 21 Table 5 summarizes macular thickness data obtained from a sample of 12 studies (including this study) evaluating several populations in 11 different countries with different OCT units. Seven of these studies had a population that was older than 40 years.…”

“…Three scans were taken using the OCT macular horizontal and vertical 3D protocols to measure the macular thickness 21 and mean values were calculated. An area of 9x9 mm centered in the fovea was analyzed in agreement with the Early Treatment Diabetic Retinopathy Study (ETDRS) map.…”

Impact of optical coherence tomography scan direction on the reliability of peripapillary retinal nerve fiber layer measurements

“…Nowadays, there are several OCT instruments available for clinical use, each includes its own segmentation algorithm software to delineate the retinal layers. Precision studies are needed to know how consistent the measurements of the retinal layers are, since the precision depends on the segmentation algorithm, scan resolution, scan direction, and acquisition time [ 16 – 19 ]. Modern OCT devices allow the clinician to customize the scan settings, such as the number of A- and B-scans, scan length, or scan direction.…”

Effect of image quality fluctuations on the repeatability of thickness measurements in swept-source optical coherence tomography

“…These parameters are helpful to monitor disease progression because repeated measurements are performed over time at the same anatomical region of an individual patient. Both SD-OCT and SS-OCT have demonstrated repeatability and reproducibility for clinical use 4 – 7 , which is an important reason for the widespread use of OCT in the diagnosis and management of various ocular conditions, including glaucoma.…”