Estimation of ocular volume from axial length

Nagra, Manbir; Gilmartin, Bernard; Logan, Nicola S

doi:10.1136/bjophthalmol-2013-304652

Cited by 20 publications

(27 citation statements)

References 18 publications

(17 reference statements)

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“…The data indicate that, similar to our findings on total ocular volume (Nagra et al. ), accurate estimates of TSA cannot be made from the application of a spherical model based simply on longitudinal axial length, particularly with regard to shorter axial lengths (Table ,. 2,Fig.…”

Section: Discussionsupporting

confidence: 81%

“…; Nagra et al. ). A T2‐weighted scan was used to demarcate fluid‐based intraocular structures for each eye and thus provide high‐contrast delineation of the internal surface of the eye including the vitreous‐retina interface.…”

Section: Methodsmentioning

confidence: 98%

“…; Nagra et al. ); the technique has been applied previously to the measurement of internal ocular volume and ocular shape (Gilmartin et al. ; Nagra et al.…”

Section: Methodsmentioning

confidence: 99%

“…; Nagra et al. ). As the technique is based on high‐contrast delineation of the vitreo‐retinal interface it can also be used to determine the internal surface area of the retina.…”

Section: Introductionmentioning

confidence: 98%

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Determination of retinal surface area

et al. 2017

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Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P < 0.01) which, contrasted with ST (365 ± 43 mm ), was significant for IT (340 ± 40 mm P < 0.01), SN (337 ± 40 mm P < 0.01) and IN (321 ± 39 mm P < 0.01) quadrants. For all quadrants, QRSA was significantly correlated with AL (P < 0.01) and exhibited equivalent increases in retinal area/mm increase in AL. Although the differences between QRSAs are relatively small, there was evidence of concordance with reported inter-quadrant patterns of susceptibility to retinal breaks associated with PVD. The data allow AL to be converted to QRSAs, which will assist further work on inter-quadrant structural variation.

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Section: Discussionsupporting

confidence: 81%

Section: Methodsmentioning

confidence: 98%

“…; Nagra et al. ); the technique has been applied previously to the measurement of internal ocular volume and ocular shape (Gilmartin et al. ; Nagra et al.…”

Section: Methodsmentioning

confidence: 99%

“…; Nagra et al. ). As the technique is based on high‐contrast delineation of the vitreo‐retinal interface it can also be used to determine the internal surface area of the retina.…”

Section: Introductionmentioning

confidence: 98%

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Determination of retinal surface area

et al. 2017

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“…Nagra et al 5 emphasize the likely importance of ocular volume rather than axial length and in a study of total ocular volume from MRI scans of 67 adults they observed axial length and corneal radius to predict ocular volume. The authors postulate that ocular volume rather than axial length might be a structural correlate for IOP elevation after invitreal injection.…”

mentioning

confidence: 99%