Position of Central Retinal Vascular Trunk and Preferential Location of Glaucomatous Damage in Myopic Normal-Tension Glaucoma

Prediction of Axial Length From Macular Optical Coherence Tomography Using Deep Learning Model

Purpose

The purpose of this study was to develop a deep learning model for predicting the axial length (AL) of eyes using optical coherence tomography (OCT) images.

Methods

We retrospectively included patients with AL measurements and OCT images taken within 3 months. We utilized a 5-fold cross-validation with the ResNet-152 architecture, incorporating horizontal OCT images, vertical OCT images, and dual-input images. The mean absolute error (MAE), R-squared (R2), and the percentages of eyes within error ranges of ±1.0, ±2.0, and ±3.0 mm were calculated.

Results

A total of 9064 eyes of 5349 patients (total image number of 18,128) were included. The average AL of the eyes was 24.35 ± 2.03 (range = 20.53-37.07). Utilizing horizontal and vertical OCT images as dual inputs, deep learning models predicted AL with MAE and R2 of 0.592 mm and 0.847 mm, respectively, in the internal test set (1824 eyes of 1070 patients). In the external test set (171 eyes of 123 patients), the deep learning models predicted AL with MAE and R2 of 0.556 mm and 0.663 mm, respectively. Regarding error margins of ±1.0, ±2.0, and ±3.0 mm, the dual-input models showed accuracies of 83.50%, 98.14%, and 99.45%, respectively, in the internal test set, and 85.38%, 99.42%, and 100.00%, respectively, in the external test set.

Conclusions

A deep learning-based model accurately predicts AL from OCT images. The dual-input model showed the best performance, demonstrating the potential of macular OCT images in AL prediction.

Translational Relevance

The study provides new insights into the relationship between retinal and choroidal structures and AL elongation using artificial intelligence models.

How is eyeball growth associated with optic nerve head shape and glaucoma? The Lamina cribrosa/Bruch's membrane opening offset theory

The optic nerve head (ONH) is a complex structure wherein the axons of the retinal ganglion cells extrude from the eyeball through three openings: 1) the Bruch's membrane opening (BMO) in the retinal layer, 2) the anterior scleral canal opening in the anterior scleral layer, and 3) the lamina cribrosa (LC). Eyeball expansion during growth induces an offset among openings, since the expansion affects the inner retinal and outer scleral layers differently: the posterior polar retinal structure is preserved by the preferential growth in the equatorial region, whereas no such regional difference is observed in the scleral layer. The various modes and extents of eyeball expansion result in diverse directionality and amount of offset among openings, which causes diverse ONH morphology in adults, especially in myopia. In this review, we summarize the ONH changes that occur during myopic axial elongation. These changes were observed prospectively in our previous studies, wherein LC shift and subsequent offset from the BMO center could be predicted by tracing the central retinal vascular trunk position. This offset induces the formation of γ-zone parapapillary atrophy or externally oblique border tissue. As a presumptive site of glaucomatous damage, the LC/BMO offset may render the LC pores in the opposite direction more vulnerable. To support such speculation, we also summarize the relationship between LC/BMO offset and glaucomatous damage. Indeed, LC/BMO offset is not only the cause of diverse ONH morphology in adults, but is also, potentially, an important clinical marker for assessment of glaucoma.

Association between eyeball asymmetry and offset of openings in optic nerve head canal assessed by posterior polar eyeball topography

We investigated three-dimensional (3D) eyeball protrusion and its association with the offset between the lamina cribrosa (LC) and Bruch's membrane opening (BMO). 3D-MRI scans were taken from 93 subjects (186 eyes). An ellipsoid was fitted along the posterior 2/3 contour of each eyeball. Eyeball asymmetry with focal bulging was determined by the existence of an adjacent outward protrusion/reciprocal inward depression pair, and the angular deviation of the outermost protruded point (OPP) was measured from the nasal side of the fovea-BMO axis. The LC/BMO offset was evaluated by measuring the central retinal vascular trunk (CRVT) location from the BMO center: (1) the angular deviation and (2) the offset index as the ratio between the CRVT-BMO center distance and the BMO radius in the same direction. Seventy-nine eyes (42%) were classified as having eyeball asymmetry, which had a more superior LC/BMO offset (P < 0.001) and a larger offset index (P = 0.002). In those eyes, the angular deviation of the OPP showed a significant correlation with that of the LC/BMO offset (r = -0.724, P < 0.001), as did protrusion depth with the offset index (r = 0.291, P = 0.009). The presence of eyeball asymmetry was associated with superior LC/BMO offset (P = 0.004) and larger offset index (P = 0.009). Superior LC/BMO offset was associated with older age (P < 0.001), shorter axial length (P < 0.001) and inferior location of OPP (P < 0.001). The location and extent of focal bulging were closely associated with those of LC/BMO offset. This indicates that focal bulging during expansion might be associated with diverse directionality of LC/BMO offset.

Optic nerve head factors associated with initial central visual field defect in primary open-angle glaucoma

We investigated optic nerve head factors associated with initial parafoveal scotoma (IPFS) in primary open-angle glaucoma. Eighty (80) patients with an IPFS and 84 patients with an initial nasal step (INS) were compared. Central retinal vascular trunk (CRVT) deviation from the Bruch's membrane opening (BMO) center was measured as a surrogate of lamina cribrosa (LC)/BMO offset, and its obliqueness was defined as the absolute value of angular deviation from the fovea-BMO axis. Proximity of retinal nerve fiber layer defect (RNFLD) was defined as the angular deviation of the inner RNFLD margin from the fovea-BMO axis. Microvasculature dropout (MvD) was defined as a focal sectoral capillary dropout with no visible microvascular network identified in the choroidal layer. Factors associated with IPFS, as compared with INS, were assessed using logistic regression analyses and conditional inference tree analysis. The IPFS group had more oblique CRVT offset (P < 0.001), RNFLD closer to the fovea (P < 0.001), more MvD (P < 0.001), and more LC defects (P < 0.001) compared to the INS group. In logistic regression analyses, obliqueness of CRVT offset (P = 0.002), RNFLD proximity (P < 0.001), and MvD (P = 0.001) were significant factors influencing the presence of IPFS. Conditional inference tree analysis showed that RNFLD closer to the fovea (P < 0.001) in the upper level, more oblique CRVT offset (P = 0.013) and presence of MvD (P = 0.001) in the lower level were associated with the probability of having IPFS. IPFS was associated with closer RNFLD location to the fovea when assessed from the BMO. Oblique LC/BMO offset may not only mask RNFLD proximity to the fovea due to a deviated funduscopic disc appearance, but also potentiate IPFS via focal LC defect and MvD.

Scanning Laser Ophthalmoscopy Demonstrates Pediatric Optic Disc and Peripapillary Strain During Horizontal Eye Rotation

Purpose: We employed automated analysis of scanning laser ophthalmoscopy (SLO) to determine if mechanical strains imposed on disc, and retinal and choroidal vessels during horizontal duction in children differ from those of adults.Methods: Thirty-one children aged 11.3 ± 2.7 (standard deviation) years underwent SLO in central gaze, and 35° ab- and adduction. Automated registration with deep learning-based optical flow analysis quantified vessel deformations as horizontal, vertical, shear, and equivalent strains. Choroidal vessel displacements in lightly pigmented fundi, and central disc vessel displacements, were also observed.Results: As in adults, strain in vessels during horizontal duction was greatest at the disc and decreased with distance from it. Strain in the pediatric disc was similar to published values in young adults,1 but in the peripapillary region was greater and propagated significantly more peripherally to at least three disc radii from it. During adduction in children, the nasal disc was compressed and disc vessels distorted, but the temporal half experienced tensile strain, while peripapillary tissues were compressed. The pattern was similar but strains were less in abduction (p < .001). Choroidal vessels were visualized in 24 of the 62 eyes and shifted directionally opposite overlying retinal vessels.Conclusions: Horizontal duction deforms the normal pediatric optic disc, central retinal vessels, peripapillary retina, and choroid, shearing the inner retina over the choroid. These mechanical effects occur at the sites of remodeling of the disc, sclera, and choroid associated with typical adult features that later emerge later, including optic cup enlargement, temporal disc tilting, and peripapillary atrophy.

Morphological differences of the neuroretinal rim between temporally tilted and non-tilted optic discs in healthy eyes

This study aimed to compare morphological differences of the neuroretinal rim between the temporally tilted and non-tilted optic discs in healthy eyes. We prospectively enrolled participants aged 20-40 years with temporally tilted or non-tilted optic discs. The optic nerve head parameters were analyzed using spectral domain-optical coherence tomography. The angle between the Bruch's membrane opening (BMO) plane and BMO-minimum rim width (BMO-MRW) was termed "BMO-MRW angle". Peripapillary retinal nerve fiber layer thickness (pRNFLT) and BMO-based parameters were compared between the temporally tilted and non-tilted disc groups. As a result, 55 temporally tilted disc eyes and 38 non-tilted disc eyes were analyzed. Global pRNFLT, global BMO-MRW, and total BMO-minimum rim area (BMO-MRA) were similar between the two groups (p = 0.138, 0.161, and p = 0.410, respectively). In the sectoral analysis, temporally tilted disc group exhibited thicker BMO-MRW in the temporal sector (p = 0.032) and thinner in the nasal superior and nasal sectors (p = 0.025 and p = 0.002, respectively). Temporally tilted disc group showed larger BMO-MRA in the temporal, temporal superior, and temporal inferior sectors (p < 0.001, p < 0.001, and p < 0.016, respectively), alongside a higher BMO-MRW angle in the temporal sector and lower in the nasal superior and nasal sectors. In conclusion, the neuroretinal rim, represented by BMO-MRW and BMO-MRA, showed morphological differences between temporally tilted and non-tilted optic discs in healthy eyes. BMO-MRW and BMO-MRA showed temporalization in the same manner as pRNFLT in the temporally tilted disc eyes. The BMO-MRW angle showed that in temporally tilted disc eyes, optic nerve fibers met the BMO plane steeply in the nasal sector and gently in the temporal sector than in non-tilted disc eyes, suggesting potential stress region of optic nerve fibers in temporally tilted disc eyes.

Optic Disc Morphology and Paracentral Scotoma in Patients with Open-Angle Glaucoma and Myopia

This study's aim was to investigate the association between optic disc morphology and the occurrence of paracentral scotoma in eyes with open-angle glaucoma (OAG) and myopia. Two-hundred and eleven myopic eyes with OAG were classified into three groups according to the location of visual field (VF) defect (99 paracentral scotoma, 65 peripheral scotoma, and 47 no VF defect). Optic disc morphology was assessed based on the tilt ratio and eccentricity of the central retinal vessel trunk (CRVT). Clinical characteristics of the three groups were compared, and factors affecting the occurrence of paracentral scotoma were determined. Eyes with paracentral scotoma had a higher tilt ratio than the other groups (ps ≤ 0.04). Multiple linear regression showed that a nasal location of CRVT (p < 0.001), longer axial length (p = 0.001), and lower VF mean deviation (p = 0.021) were significantly associated with higher tilt ratio. In logistic regression analysis, tilt ratio was the only factor that was significantly associated with the occurrence of paracentral scotoma (odds ratio = 7.12, p = 0.032). In conclusion, the optic disc tilt ratio increased with nasal shift of CRVT, longer axial length, and lower VF mean deviation. Higher optic disc tilt was significantly associated with the occurrence of paracentral scotoma in eyes with OAG and myopia.

Hemisphere opposite to central retinal vascular trunk deviation is earlier affected by glaucomatous damage in primary angle-closure glaucoma

PURPOSE

The purpose of the study was to investigate whether the position of the central retinal vascular trunk (CRVT), as a surrogate for lamina cribrosa (LC) offset, is associated with the dominant hemisphere of visual field defect in primary angle-closure glaucoma (PACG) eyes.

METHODS

Central retinal vascular trunk deviation was measured from Bruch's membrane opening (BMO) centre, which was delineated by OCT imaging, using the horizontal midline as a reference. The dominant hemisphere developing visual field defect was defined as three connected abnormal points (having a p-value < 5% probability of being normal) appearing in only one hemisphere or each point of the hemisphere having a statistically worse value compared with its mirrored point in the opposite hemisphere on pattern deviation plots.

RESULTS

One hundred five (80%) of 132 eyes with PACG had dominant hemisphere of visual field defect initially: 70 eyes (67%) in the superior and 35 eyes (33%) in the inferior hemisphere. The CRVT was located superiorly in the dominant superior visual field defect group (p < 0.001). A logistic regression analysis revealed that superior deviation of the CRVT was the only factor associated with dominant superior visual field defect (p < 0.001). Externally oblique border (EOB) presence was associated with larger BMO (p = 0.005) and angular deviation of CRVT (p = 0.002).

CONCLUSIONS

Central retinal vascular trunk deviation was associated with the dominant hemisphere of visual field defect in PACG eyes. This finding implies that the LC position relative to the BMO centre (LC/BMO offset) may incur structural vulnerability in the optic nerve head of PACG eyes.

Screening fundus photography predicts and reveals risk factors for glaucoma conversion in eyes with large optic disc cupping

This study aimed to investigate the risk factors for glaucoma conversion and progression in eyes with large optic disc cupping without retinal nerve fiber layer defect (RNFLD). Five hundred forty-two eyes of 271 subjects who had a vertical cup-to-disc ratio (CDR) ≥ 0.6 without RNFLD were enrolled. Characteristics for optic disc configuration (including CDR, vertical cupping, ISNT rule, disc ovality, peripapillary atrophy [PPA]-to-disc area [DA] ratio, and lamina cribrosa pore visibility) and blood vessels (including central retinal vessel trunk [CRVT] nasalization, bayoneting of vessels, baring of circumlinear vessels, history of disc hemorrhage [DH] and vessel narrowing/sclerotic change) were evaluated. From a median follow-up of 11.3 years, 26.6% of eyes (n = 144) developed RNFLD within a median of 5.1 years. Baseline factors, including vertical CDR ≥ 0.7 (hazard ratio [HR] = 2.12), vertical cupping (HR = 1.93), ISNT rule violation (HR = 2.84), disc ovality ≥ 1.2 (HR = 1.61), PPA-to-DA ratio ≥ 0.4 (HR = 1.77), CRVT nasalization ≥ 60% (HR = 1.77), vessel narrowing/sclerotic change (HR = 2.13), DH history (HR = 5.60), and baseline intraocular pressure ≥ 14 mmHg (HR = 1.70) were significantly associated with glaucoma conversion (all Ps < 0.05). An HR-matched scoring system based on initial fundus photography predicted glaucoma conversion with specificity of 90.4%. Careful examination of the optic nerve head and vascular structures can help to predict the risk of glaucoma conversion in eyes with large optic disc cupping.

Offset of openings in optic nerve head canal at level of Bruch's membrane, anterior sclera, and lamina cribrosa

We compared the central retinal vascular trunk (CRVT) position, as a surrogate of lamina cribrosa (LC) offset, with the anterior scleral opening (ASCO) offset from the Bruch’s membrane opening (BMO). Based on the BMO-centered radial scans, the BMO and ASCO margins were demarcated, and each center was determined as the center of the best-fitted ellipse for each margin. The ASCO/BMO offset was defined as the offset between each center. Angular deviations and the extent of ASCO and CRVT offsets from the BMO center were compared directly. Incomplete demarcation of ASCO was found in 20%, which was associated with a larger BMO area and a larger ASCO offset from the BMO. The angular deviation of ASCO offset was associated with that of CRVT offset and that of the longest externally oblique border. The ASCO offset was smaller than the CRVT offset, and, unlike the CRVT offset, it was rarely deviated to the inferior side. The complete ASCO margin might not be demarcatable when determined on BMO-centered radial scans in the presence of an offset. Also, the ASCO, which reflects only the superficial scleral layer, might not reflect the LC position, because the LC might be shifted further from the ASCO.

Vertical Position of the Central Retinal Vessel in the Optic Disc and Its Association With the Site of Visual Field Defects in Glaucoma

PURPOSE

The purpose of this study was to investigate the association between the vertical position of the central retinal vessel (CRV) within the optic nerve head (ONH) and the site of visual field defects (VFDs) in glaucoma.

DESIGN

Cross-sectional study.

METHODS

The vertical position of the CRV was identified in 134 glaucoma eyes and 61 normal eyes at the point at which CRV exited the lamina cribrosa (LC) onto the ONH surface, by using spectral-domain optical coherence tomography (exit position). The position was also identified at the entry point into the LC from the retrolaminar ONH region (entry position), which was little influenced by glaucomatous LC deformation, therefore close to the original position before the glaucoma development. Positions were compared among glaucoma eyes with different sites of VFDs, and between glaucoma and normal eyes.

RESULTS

In glaucoma eyes, the entry position of the CRV was in the superior ONH region in 63.0% of eyes with superior VFDs and in the inferior ONH region in 97.8% of eyes with inferior VFDs (P < .0001). The exit position exhibited a similar percentage. The vertical CRV positions were not significantly different between glaucoma and normal eyes, both at the entry and exit positions.

CONCLUSIONS

Eyes with CRVs in the superior ONH region were significantly more likely to form VFDs in the superior hemifields and vice versa. The vertical position of the CRV was little altered by the development of glaucoma. The original position of the CRV before the development of glaucoma may influence regional susceptibility to glaucomatous stress and may be useful in predicting initial sites of VFDs.

Central retinal vascular trunk deviation in unilateral normal-tension glaucoma

Purpose

To investigate whether the position of the central retinal vascular trunk (CRVT), as a surrogate of lamina cribrosa (LC) offset, was associated with the presence of glaucoma in normal-tension glaucoma (NTG) patients.

Methods

The position of the CRVT was measured as the deviation from the center of the Bruch’s membrane opening (BMO), as delineated by spectral-domain optical coherence tomography imaging. The offset index was calculated as the distance of the CRVT from the BMO center relative to that of the BMO margin. The angular deviation of CRVT was measured with the horizontal nasal midline as 0° and the superior location as a positive value. The offset index and angular deviation were compared between glaucoma and fellow control eyes within individuals.

Results

NTG eyes had higher baseline intraocular pressure (P = 0.001), a larger β-zone parapapillary atrophy area (P = 0.013), and a larger offset index (P<0.001). In a generalized linear mixed-effects model, larger offset index was the only risk factor of NTG diagnosis (OR = 31.625, P<0.001). A generalized estimating equation regression model revealed that the offset index was larger in the NTG eyes than in the control eyes for all ranges of axial length, while it was the smallest for the axial length of 23.4 mm (all P<0.001).

Conclusions

The offset index was larger in the unilateral NTG eyes, which fact is suggestive of the potential role of LC/BMO offset as a loco-regional susceptibility factor.

Angular Location of Retinal Nerve Fiber Layer Defect: Association With Myopia and Open-Angle Glaucoma

Purpose

To compare retinal nerve fiber layer (RNFL) defects' angle measurements determined from the center of the optic disc and Bruch's membrane opening (BMO), as a function of myopia and open-angle glaucoma (OAG) subtypes.

Methods

In total, 118 patients with OAG were grouped by axial length (AL; high myopia, AL >26 mm; mild to moderate myopia, 24 ≤ AL ≤26 mm; nonmyopia, AL <24 mm) and OAG subtype (normal-tension glaucoma [NTG], high-tension glaucoma [HTG]). The disc and BMO centers were determined by a merged image of red-free fundus photography and spectral-domain optical coherence tomography. The angular location of the RNFL defect close to the fovea (angle α) was measured from the disc center and BMO center, respectively (angle αdisc and angle αBMO). The difference between angle αdisc and αBMO (Δα), as well as the RNFL defect width (angle γ), was evaluated.

Results

Angle αdisc was smaller in myopic eyes and correlated significantly with AL (P = 0.001), whereas it did not differ among OAG subgroups. Angle αBMO and angle γ were not different in the myopic and OAG subgroups. The Δ α was larger for eyes with higher degree of myopia and had significant correlation with AL (P < 0.001) and was larger in NTG eyes than in HTG eyes (P = 0.023).

Conclusions

The angular location of the RNFL defect measured from the disc center, but not from the BMO center, was closer to the fovea for glaucomatous eyes with higher values of AL. The present study may facilitate understanding of the characteristic locational pattern of the RNFL defect in myopic glaucomatous eyes.

Short foveo-disc distance in situs inversus of optic disc

Situs inversus of optic disc (SIOD) is thought to be a congenital optic disc abnormality that is caused by dysversion of optic nerve insertion. SIOD, however, has many additional features that cannot be explained by abnormal optic-nerve-insertion directionality. In this study, we measured the distance between the fovea and disc in 22 eyes of 15 SIOD patients. For comparison, two control eyes were matched with each SIOD eye by age and axial length. The vertical distance between the temporal vascular arcades also was measured. The foveo-disc distance was shorter in the SIOD eyes than in the control eyes, while the inter-arcade distance did not differ. Further, we measured the circumpapillary retinal nerve fiber layer thickness, which showed nasal crowding of two humps in the SIOD eyes. This nasal crowding disappeared when we shifted the circle scan by the mean difference (465 μm) of the foveal-disc distance between the two groups. Our findings suggest that the optic disc was located closer to the fovea than it would have been normally. Thus, SIOD might reflect incomplete expansion of the posterior pole in the direction of the fovea-disc axis.

Relationship between Three-Dimensional Magnetic Resonance Imaging Eyeball Shape and Optic Nerve Head Morphology

PURPOSE

To determine if the 3-dimensional (3D) eyeball shape is associated with the positions of the central retinal vascular trunk (CRVT) and the externally oblique border (EOB) in the optic nerve head (ONH).

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

Fifty-six subjects (112 eyes) with a diagnosis of glaucoma or glaucoma suspect.

METHODS

The eyeball shape on 3D magnetic resonance imaging (MRI) scans was classified according to the dimension of the longest diameter: axial dimension (prolate sphere), group 1; horizontal dimension (horizontally oblate sphere), group 2; and vertical dimension (vertically oblate sphere), group 3. The deviation of the CRVT, as a surrogate of lamina cribrosa (LC) shift, was measured from the center of the Bruch's membrane opening (BMO) demarcated by OCT imaging, with the horizontal midline as 0° and the superior location as a positive value. The angular location of the longest EOB was also measured.

MAIN OUTCOME MEASURE

Positions of CRVT and EOB according to the 3D eyeball shape.

RESULTS

Among 112 eyes, 54 (48%) had a prolate shape (group 1), 23 (21%) had a horizontally oblate shape (group 2), and 35 (31%) had a vertically oblate shape (group 3). The angular deviation of the CRVT differed among the groups: to the nasal side in group 1, to the temporal side in group 2, and along the vertical meridian in group 3. In cases of asymmetric eyeball shape, the CRVT was deviated toward the undergrown side from the overgrown side, regardless of grouping. The angular location of the longest EOB was in the direction opposite to the CRVT position (P < 0.001). A generalized estimating equation analysis revealed that the temporal location of the CRVT was associated with older age (P = 0.001), nasal location of the longest EOB (P < 0.001), and oblate shape of the eyeball (P < 0.001, group 2; P = 0.007, group 3).

CONCLUSIONS

The position of the CRVT and EOB were associated with the 3D eyeball shape. Considering that infant ONH morphology is highly uniform, various modes of eyeball expansion during growth can result in diverse directionalities of offset between the LC and the BMO in adults.

Characteristics of Focal Gamma Zone Parapapillary Atrophy

Purpose

The purpose of this study was to investigate the characteristics of focal γ-zone parapapillary atrophy (focal γPPA) in patients with primary open-angle glaucoma (POAG) using spectral-domain optical coherence tomography (SD-OCT).

Methods

Three groups of POAG eyes (n = 214) were defined according to the circumferential extent of Bruch's membrane (BM) within the β-zone PPA, as follows: (1) no γPPA (intact BM; n = 81), (2) conventional γPPA (γPPA involving the fovea-BM-opening axis; n = 89), and (3) focal γPPA (γPPA not involving the fovea-BM-opening axis; n = 44). Clinical and ocular characteristics, including age, axial length (AXL), and focal lamina cribrosa (LC) defects were compared among the three groups.

Results

The focal γPPA group was significantly older (60.6 ± 11.0 years) and had shorter AXL (24.10 ± 1.34 mm) than those of the conventional γPPA group (46.2 ± 13.8 years and 26.53 ± 1.61 mm, respectively; P < 0.001). These values of the focal γPPA group were similar to those of the no γPPA group (23.73 ± 0.97 mm for AXL and 64.0 ± 13.0 years for age). The focal γPPA group had a significantly higher prevalence of focal LC defects than did the other two groups (70.5% [31/44] for the focal γPPA group versus 46.1% [41/89] for the conventional γPPA group versus 37.0% [30/81] for the no γPPA group; P = 0.002).

Conclusions

Focal γPPA was differentiated from conventional γPPA by older age and shorter AXL. Further, focal γPPA was frequently accompanied by focal LC defects. Longitudinal studies elucidating whether focal LC defects and focal γPPA share common pathogenesis are warranted.

Hemisphere opposite to vascular trunk deviation is earlier affected by glaucomatous damage in myopic high-tension glaucoma

PURPOSE

To investigate whether the position of the central vascular trunk, as a surrogate of lamina cribrosa (LC) shift, is associated with the initial hemisphere of visual field defect in myopic high-tension glaucoma (HTG) eyes.

METHODS

The deviation of the central vascular trunk was measured from the center of the Bruch's membrane opening (BMO), which was delineated by OCT imaging. The angular deviation was measured with the horizontal nasal midline as 0° and the superior location as a positive value. The initial hemisphere developing visual field defect was defined as three connected abnormal points (having a P value with less than 0.5% probability of being normal) appearing in only one hemisphere in pattern deviation plots. If those points were observed in both hemispheres initially, the eye was classified as bi-hemispheric visual field defect.

RESULTS

Initially, 36 eyes (44%) had superior visual field defects, 27 (33%) inferior visual field defects, and 18 (22%) bi-hemispheric visual field defects. After a mean follow-up of 5 years, the number of bi-hemispheric visual field defects had increased to 34 (42%). A logistic regression analysis revealed that inferior deviation of vascular trunk was the only factor associated with initial inferior visual field defect (P = 0.001), while initial bi-hemispheric visual field defects were associated with worse mean deviation at initial visits (P<0.001). A conditional inference tree analysis showed that both the angular deviation (P<0.001) and initial mean deviation (P = 0.025) determined the initial hemispheres developing visual field defect.

CONCLUSIONS

Although both hemispheres were involved as glaucoma progression, the axons on the side counter to the vascular trunk deviation were damaged earlier in HTG. This finding implies the LC shift could add additional stress to axons exposed to high intraocular pressure.

Nasalization of Central Retinal Vessel Trunk Predicts Rapid Progression of Central Visual Field in Open-Angle Glaucoma

Central visual field (CVF) loss is important in maintaining vision-related quality of life in eyes with open-angle glaucoma (OAG). The present study investigated whether nasalized location of central retinal vessel trunk (CRVT) at baseline is associated with rapid rate of CVF loss in early-stage OAG eyes. This study included 76 OAG eyes with high nasalization CRVT [HNL] group and 75 OAG eyes with low nasalization CRVT [LNL] group matched for glaucoma severity at baseline that showed progressive visual field (VF) loss. The rates of mean threshold changes at various regions were compared in the two groups using a linear mixed model. Clinical variables associated with rapid rate of CVF progression were also identified using a linear mixed model. The rate of CVF loss in the central 10° was significantly higher in the HNL group than that in the LNL group (-0.452 dB/year vs. -0.291 dB/year, P < 0.001). The average and inferior hemi-macular ganglion cell inner plexiform layer (GCIPL) progression rates were significantly faster in the HNL group than in the LNL group (P < 0.05). Nasalized location of CRVT was an independent predictor of a more rapid VF loss in the central 10° region (P < 0.05).

Position of Central Vascular Trunk and Shape of Optic Nerve Head in Newborns

Purpose

To investigate the baseline position of the central vascular trunk (CVT) and the characteristics of the optic nerve head (ONH) in newborns.

Methods

CVT position was evaluated based on fundus images obtained from newborns who had undergone eye-screening examinations. It was then graded according to the optic disc area as follows: grade 1, within central 4%; grade 2, within central 9%; grade 3, within central 16%; grade 4, within central 25%; grade 5, outside central 25% of optic disc area. The direction of the CVT position was determined in cases of grade 2 or more as superior, inferior, nasal, and temporal, relative to the optic disc center. The ovality index and the vertical cup-to-disc ratio were determined as well.

Results

In 1000 fundus images from 1000 newborns, 87.1% showed grade 1 (95% confidence interval 84.7-88.8), and 10.7% showed grade 2. The most common CVT direction was central (87.1%, grade 1), followed by nasal (11.0%) and inferior (1.2%). The ovality index was 1.28 ± 0.09 (range, 1.01-1.61). The ONH shape was vertically oval and highly uniform. The average vertical cup-to-disc ratio was 0.29 ± 0.13 (range, 0.00-0.67).

Conclusions

The CVT of newborns was located in the central area of the ONH in most cases. The shape of the optic disc was vertically oval, and very similar among the newborns. Considering the high variability of ONH morphology and the diverse location of the CVT in adults, our result suggests that the shape of the ONH and the CVT position might change during eyeball growth.