Influence of Scan Radius Correction for Ocular Magnification and Relationship Between Scan Radius With Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography

Bayraktar, Şükrü; Bayraktar, Zerrin; Yılmaz, Ömer Faruk

doi:10.1097/00061198-200106000-00004

Cited by 57 publications

(49 citation statements)

References 16 publications

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“…Only minimal differences within 5 µm in thickness were detected in most of the sections, including central macular thickness (table 3). Bayraktar et al [5] reported that if an area of 1.73 mm in diameter is used to analyze RNFL thickness, the area of interest will expand by 0.06 mm as the axial length increases by 1 mm. As a result, areas that are further away from the borders of the optic disc will be analyzed, resulting in a lower value of RNFL thickness.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the measurements obtained may be affected by axial length of the eyes and refractive power [4,5]. However, there have been few clinical investigations regarding the extent to which this influences the results.…”

Section: Introductionmentioning

confidence: 99%

“…When the RNFL is measured, the scan involves circular areas of constant diameter with the center positioned at the optic disc. Depending on the axial length, higher magnification is applied in case of myopic eyes, so a circular area of larger diameter around the optic disc will be scanned, and this may explain the lower values of RNFL thickness [5]. …”

Section: Introductionmentioning

confidence: 99%

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Effects of Refractive Power on Macular Thickness Measurement Using Spectral-Domain Optical Coherence Tomography

Lee

Shin²,

Shin³

et al. 2015

Ophthalmologica

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Purpose: To investigate the effects of refractive power on macular thickness measurements by spectral-domain optical coherence tomography (SD-OCT). Subjects and Methods: For this prospective cohort study, a total of 50 eyes from 50 normal subjects with no systemic or ocular disease and no history of ocular surgery were studied from February 2014 to May 2014. We used soft contact lenses with a wide range of diopters to change the refractive power. The macular thickness of uncorrected eyes without contact lenses was measured by SD-OCT, and we compared the findings with the results of subsequent investigations in which macular thickness was measured in the presence of soft contact lenses of different diopters (-8, -4, 0, +4, and +8). We divided the patients into three groups according to the axial length (AL) and analyzed the effect of induced refraction change. The main outcome measure was macular thickness measured by OCT. Results: The average age of the subjects was 28.0 ± 3.4 years (mean ± SD), and included 17 eyes with normal AL, 18 eyes with mid-range AL, and 15 eyes with long AL. The central macular thickness was 254.5 ± 17.5 µm for eyes without contact lenses, which was not significantly different from the measurements in the presence of plano contact lenses (254.2 ± 18.1 µm). Even with soft contact lenses of four different diopters (-8, -4, +4, and +8), central macular thickness (254.4 ± 16.2, 253.7 ± 17.3, 257.3 ± 17.9, and 256.9 ± 17.9 µm, respectively) was not significantly different from that of naked eyes in each group. Conclusion: These results suggest that central macular thickness measured by SD-OCT is unaffected by refractive power.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Refractive Power on Macular Thickness Measurement Using Spectral-Domain Optical Coherence Tomography

Lee

Shin²,

Shin³

et al. 2015

Ophthalmologica

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“…Given that AL-induced magnification can affect the OCT scan radius, 19 the effect of magnification on OCT macular measurements should be considered in myopic eyes. Because the methodology for correction of the magnification effect on macular thickness/volume measured using OCT remains unclear in previous studies, [6][7][8][9][10][11][13][14][15] the effect of magnification was not corrected as in the present study.…”

Section: Macular Thickness In Myopic Eyes By Spectral-domain Optical mentioning

confidence: 99%

Macular thickness and volume of myopic eyes measured using spectral‐domain optical coherence tomography

Hwang

Kim

2012

Clinical and Experimental Optometry

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“…10 These methods have been compared by Garway-Heath et al, 9 who concluded that the simplest approach of using only axial length to correct for magnification error was accurate and produced very similar results to the more detailed calculations that incorporated keratometry, refractive error, and lens thickness. 15 Given most eye clinics have access to devices that measure axial length and that incorporating axial length has been shown to increase the accuracy of optic nerve head size and retinal layer thickness evaluated by OCT, [16][17][18][19][20][21][22][23] we hypothesize that OCTA image magnification correction using axial length measurement is feasible and necessary for accurate determination of OCTAderived variables.…”

mentioning

confidence: 99%

Axial Length Variation Impacts on Superficial Retinal Vessel Density and Foveal Avascular Zone Area Measurements Using Optical Coherence Tomography Angiography

Sampson

Gong

et al. 2017

Invest. Ophthalmol. Vis. Sci.

237

227

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Citation: Sampson DM, Gong P, An D, et al. Axial length variation impacts on superficial retinal vessel density and foveal avascular zone area measurements using optical coherence tomography angiography. Invest Ophthalmol Vis Sci. 2017;58:3065-3072. DOI:10.1167/iovs.17-21551 PURPOSE. To evaluate the impact of image magnification correction on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurements using optical coherence tomography angiography (OCTA). METHODS.Participants with healthy retinas were recruited for ocular biometry, refraction, and RTVue XR Avanti OCTA imaging with the 3 3 3-mm protocol. The foveal and parafoveal SRVD and FAZA were quantified with custom software before and after correction for magnification error using the Littman and the modified Bennett formulae. Relative changes between corrected and uncorrected SRVD and FAZA were calculated.RESULTS. Forty subjects were enrolled and the median (range) age of the participants was 30 (18-74) years. The mean (range) spherical equivalent refractive error was À1.65 (À8.00 to þ4.88) diopters and mean (range) axial length was 24.42 mm (21.27-28.85). Images from 13 eyes were excluded due to poor image quality leaving 67 for analysis. Relative changes in foveal and parafoveal SRVD and FAZA after correction ranged from À20% to þ10%, À3% to þ2%, and À20% to þ51%, respectively. Image size correction in measurements of foveal SRVD and FAZA was greater than 5% in 51% and 74% of eyes, respectively. In contrast, 100% of eyes had less than 5% correction in measurements of parafoveal SRVD.CONCLUSIONS. Ocular biometry should be performed with OCTA to correct image magnification error induced by axial length variation. We advise caution when interpreting interocular and interindividual comparisons of SRVD and FAZA derived from OCTA without image size correction.

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Influence of Scan Radius Correction for Ocular Magnification and Relationship Between Scan Radius With Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography

Cited by 57 publications

References 16 publications

Effects of Refractive Power on Macular Thickness Measurement Using Spectral-Domain Optical Coherence Tomography

Effects of Refractive Power on Macular Thickness Measurement Using Spectral-Domain Optical Coherence Tomography

Macular thickness and volume of myopic eyes measured using spectral‐domain optical coherence tomography

Axial Length Variation Impacts on Superficial Retinal Vessel Density and Foveal Avascular Zone Area Measurements Using Optical Coherence Tomography Angiography

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