Parapapillary drusen of the retinal pigment epithelium

PURPOSE

To describe the occurrence, morphology and associations of parapapillary drusen of the retinal pigment epithelium (RPE-drusen).

METHODS

Using light microscopy, we histomorphometrically examined enucleated human eyes.

RESULTS

The study included 83 eyes (axial length: 25.9 ± 3.2 mm; range: 20.0-35.0 mm). Eyes with parapapillary RPE-drusen (n = 29 (35%) eyes) as compared to those without drusen had a significantly shorter axial length (24.0 ± 1.8 mm vs 27.0 ± 3.3 mm; p < 0.001), higher prevalence (27/29 vs 12/54; p < 0.001) and longer width (213 ± 125 μm vs 96 ± 282 μm; p < 0.0001) of parapapillary alpha zone, and thicker BM in parapapillary beta zone (8.4 ± 2.7 μm vs 3.9 ± 2.0 μm; p < 0.001) and alpha zone (6.6 ± 3.9 μm vs 4.4 ± 1.5 μm; p = 0.02). Prevalence of parapapillary RPE-drusen was 27 (69%) out of 39 eyes with alpha zone. Beneath the RPE-drusen and in total alpha zone, choriocapillaris was open, while it was closed in the central part of parapapillary beta zone. BM thickness was thicker (p = 0.001) in alpha zone than beta zone, where it was thicker (p < 0.001) than in the region outside of alpha/beta zone. BM thickness outside of alpha/beta zone was not correlated with prevalence of parapapillary RPE-drusen (p = 0.47) or axial length (p = 0.31). RPE cell density was higher in alpha zone than in the region adjacent to alpha zone (22.7 ± 7.3 cells/240 μm vs 18.3 ± 4.1 cells/240 μm; p < 0.001). In the parapapillary RPE-drusen, RPE cells were connected with a PAS-positive basal membrane.

CONCLUSIONS

Parapapillary RPE-drusen as fibrous pseudo-metaplasia of the RPE were associated with shorter axial length, higher prevalence and larger size of alpha zone, and thicker BM in alpha zone and beta zone. The RPE-drusen may be helpful to differentiate glaucomatous parapapillary beta zone from myopic beta zone.

Drusen in the macula and parapapillary region

PURPOSE

To examine histological characteristics and differences between drusen beneath the retinal pigment epithelium (small hard drusen) located in the macula and located in the parapapillary region.

METHODS

We histomorphometrically examined human eyes enucleated due to uveal melanomas or secondary angle-closure glaucoma.

RESULTS

The study included 106 eyes (age, 62.6 ± 15.2 years) with macular drusen (n = 7 globes) or parapapillary drusen (n = 29 eyes) and 70 eyes without drusen. In all drusen, periodic-acid-Schiff-positive material was located between the RPE basal membrane and the inner collagenous layer of Bruch's membrane (BM). Macular drusen as compared with parapapillary drusen had lower height (15.2 ± 10.1 µm versus 34.3 ± 19.8 µm; P = 0.003), while both groups did not differ significantly in basal drusen width (74.0 ± 36.3 µm versus 108.7 ± 101.0 µm; P = 0.95). Eyes with macular drusen and eyes without drusen did not differ significantly in BM thickness (2.74 ± 0.44 µm versus 2.55 ± 0.88 µm; P = 0.57) or in RPE cell density (35.4 ± 10.4 cells/480 µm versus 32.8 ± 7.5 cells/480 µm; P = 0.53), neither in the drusen region nor in the drusen vicinity, while BM thickness (4.60 ± 1.490 µm; P < 0.001) and RPE cell density (56.9 ± 26.8 cells/480 µm; P = 0.005) were higher at the parapapillary drusen. Eyes with macular drusen, eyes with parapapillary drusen, and eyes without drusen did not differ significantly in choriocapillaris density (all P > 0.10) and thickness (all P > 0.35). Limitations of the study, among others, were a small number and size of drusen examined, diseases leading to enucleation, lack of serial sections, limited resolution of light microscopy, and enucleation-related and histological preparation-associated artefacts.

CONCLUSIONS

The findings of this study, also taking into account its methodological limitations, suggest that macular drusen and parapapillary drusen shared the morphological feature of periodic-acid-Schiff-positive material between the RPE basal membrane and BM and that they did not vary significantly in choriocapillaris thickness and density. RPE cell density and BM thickness were higher in parapapillary drusen than in macular drusen.

Prevalence and Associations of Peripheral Arterial Disease in China: The Beijing Eye Study

PURPOSE

To explore the prevalence and associations of peripheral arterial disease (PAD) in China.

DESIGN

Population-based incidence estimate and cross-sectional study.

METHODS

The participants (n=3468) of the Beijing Eye Study underwent a detailed ophthalmologic and systemic examination including assessment of the ankle-brachial index (ABI). PAD was defined by an ABI of less than 0.9.

RESULTS

Blood pressure measurements of both arms and ankles were available for 1078 (31.1%) individuals. An ABI (mean: 1.09±0.11; median: 1.10; range: 0.25, 1.36) of <0.9 and <0.95 was found in 32 of 1078 participants (3.0%, 95% CI 2.0, 4.0) and 70 of 1078 individuals (6.5%, 95% CI 5.0, 8.0), respectively. Higher PAD prevalence (multivariable analysis) was associated with older age (odds ratio [OR] 1.08, 95% CI 1.02, 1.15; P = .009), lower level of education (OR 0.62, 95% CI 0.43, 0.90; P = .01), lower quality of life (OR 0.67, 95% CI 1.11, 2.32), higher glucose serum concentration (OR 1.36, 95% CI 1.09, 1.58; P = .006), lower estimated glomerular filtration rate (OR 0.98, 95% CI 0.96, 0.99; P = .04), and higher prevalence of retinal vein occlusions (OR 7.30, 95% CI 1.63, 32.6; P = .009). PAD prevalence was not associated with the prevalence of glaucoma (P = .53) (open-angle glaucoma: P = .42; angle-closure glaucoma: P = .57) and age-related macular degeneration (any AMD: P = .39; early AMD: P = .31; intermediate AMD: P = .92; late AMD: P = .99), prevalence (P = .26) and stage (P = .07) of diabetic retinopathy, prevalence (P = .38) and degree (P = .68) of nuclear cataract, prevalence (P = .39) and degree (P = .72) of cortical cataract, prevalence of subcapsular cataract (P = .86), prevalence of pseudoexfoliation (P = .65), intraocular pressure (P = .50), axial length (P = .56), and peripapillary retinal nerve fiber layer thickness (P = .68).

CONCLUSIONS

The PAD prevalence (3.0%, 95% CI 2.0%, 4.0%) was relatively low in this cohort from rural and urban Beijing, with older age, lower educational level, lower quality of life, higher glucose serum concentration, lower estimated glomerular filtration rate, and higher prevalence of retinal vein occlusions as main associated factors.

Bruch's membrane and Brücke's muscle in the pars plana region

PURPOSE

To examine Bruch's membrane (BM) in association with the longitudinal part of the ciliary muscle (LPCM) in the pars plana region.

METHODS

Using light microscopy, we histomorphometrically assessed BM and the LPCM in the pars plana region.

RESULTS

The histomorphometric study included 51 eyes (51 patients; mean age: 60.8 ± 15.0 years; axial length: 26.0 ± 3.3 mm; range: 21.0-36.0 mm). The LPCM (total length: 4.60 ± 1.10 mm) ended 1.15 ± 0.56 mm anterior to the ora serrata. Within the pars plana region, the LPCM (length: 2.58 ± 0.98 mm) had direct contact with BM for 1.95 ± 0.99 mm (71.1 ± 18.4% of the BM undersurface), while a capillary layer was interposed between the BM and the LPCM for 0.70 ± 0.40 mm (29.0 ± 18.4%). In the pars plana region free of LPCM close to the ora serrata, the percentage of BM covered by the capillary layer was higher than in the pars plana region containing the LPCM (63.0 ± 42.1% vs. 29.0 ± 18.4%; p < 0.001). At the LPCM end, BM was in direct contact with a collagenous tissue from the LPCM and was focally thickened as compared to BM with an underlying capillary layer (9.5 ± 5.3 μm vs. 4.3 ± 1.2 μm; p < 0.001).

CONCLUSIONS

The direct contact of BM with the LPCM in the pars plana in association with focal BM thickening at the LPCM end suggests an insertion of LPCM on the BM. Taking into account the biomechanical strength of BM, it may imply a functional unit of the LPCM with BM in the process of accommodation with a secondary movement of the posterior BM and tertiary thickening of the subfoveal choroidal space.

Prevalence and Cause of Loss of Visual Acuity and Visual Field in Highly Myopic Eyes: The Beijing Eye Study

PURPOSE

To explore the prevalence and causes of loss of visual acuity and visual field in highly myopic eyes.

DESIGN

Population-based study.

PARTICIPANTS

4439 subjects of the Beijing Eye Study underwent ophthalmological and systemic examinations including frequency doubling technology perimetry.

METHODS

High myopia was defined by a refractive error of ≤-6 diopters (D) or axial length >26.0 mm.

MAIN OUTCOME MEASURES

Prevalence of vision impairment causes.

RESULTS

212 highly myopic eyes from 154 participants were included with a mean age of 56.2 ± 9.6 years, a mean refractive error of -9.87 ± 3.70 D and a mean axial length of 27.2 ± 1.3 mm. We observed moderate/severe vision impairment (MSVI) in 40 eyes (18.9%; 95% confidence interval [CI], 13.6-24.2) and blindness in 10 eyes (4.7%; 95% CI, 1.8-7.6). Primary causes for MSVI and blindness were myopic macular degeneration (MMD) (29/50; 58%), age-related macular degeneration (1/50; 2%), and branch macular retinal vein occlusion (1/50; 2%). Secondary causes were MMD (4/50; 8%) and optic nerve atrophy (14/50, 28%), further differentiated into non-glaucomatous optic atrophy (NGOA) (9/50; 18%) and glaucomatous optic atrophy (GOA) (5/50; 10%). Prevalence of MMD as vision impairment cause increased significantly from 1/61 (1.6%) in the refractive error group of -6.00 to ≥-7.00 D, to 16/25 (64%) in the group of <-15.0 D. Higher MMD prevalence correlated with higher myopic refractive error (P < 0.001) and increased likelihood of concomitant optic neuropathy (P < 0.001). Similarly, prevalence of optic neuropathy as vision impairment cause increased from 0/61 (0%) in the refractive error group of -6.00 D to ≥-7.00 D, to 9/25 (36%) in the group of <-15.0 D. Higher optic neuropathy prevalence correlated with more myopic refraction (P < 0.001) and older age (P = 0.02).

CONCLUSIONS

In this population-based recruited cohort of highly myopic patients, optic neuropathy accounted for vision impairment in 9.0% eyes, which was lower than the prevalence of MMD as vision impairment cause (18.9%). Notably, optic neuropathy became a significant contributor to vision impairment in more advanced high myopia, reaching 36% in the group with refractive error of <-15.0 D.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Ciliary body size in chronic angle-closure glaucoma

To examine the size of the ciliary body stroma (CBS) in dependence of the morphology of the anterior chamber angle in enucleated human eyes, we histomorphometrically examined human enucleated eyes. The study included 107 eyes (with a mean axial length of 25.1 ± 2.8 mm (range 21.0-36.0 mm). The anterior chamber angle was open in 68 eyes and it was closed and endothelialized in 39 eyes. The maximal CBS width (541 ± 210 µm versus 59 ± 179 µm; P < 0.001) and the minimal CBS width (214 ± 107 µm versus 17 ± 55 µm; P < 0.001) and maximal ciliary muscle height (593 ± 557 µm versus 293 ± 111 µm; P = 0.001) were significantly smaller in the angle-closure group than in the open-angle group. Maximal CBS width increased with presence of an open anterior chamber angle (beta: 0.82; B: 517; 95% CI 435, 599; P < 0.001) and longer axial length (beta: 0.17; B: 18.2; 95% CI 4.2, 32.2; P = 0.01). Minimal CBS width increased with the presence of an open anterior chamber angle (beta: 0.48; B: 131; 95% CI 80.4, 181; P < 0.001) and a larger maximal ciliary muscle height (beta: 0.33; B: 0.28; 95% CI 0.12, 0.44; P = 0.001). Maximal ciliary muscle height correlated with the maximal CBS height (beta: 0.35; B: 0.53; 95% CI 0.25, 0.81; P < 0.001). The findings suggest that the CBS size is markedly smaller in eyes with a chronically closed endothelialized anterior chamber angle than in eyes with open angles. The tightening of the angle in eyes with angle-closure may prevent the access of aqueous humor not only to the trabecular meshwork but also to the ciliary body and may reduce the uveoscleral or uveovortex outflow pathway.

Choriocapillaris, Photoreceptors, and Inner Retinal Layer in Spatial Relationship to Parapapillary Alpha, Beta, Gamma, and Delta Zones

Purpose

To examine the spatial relationships between the retinal inner nuclear layer (INL), outer nuclear layer (ONL), retinal pigment epithelium (RPE) layer, Bruch's membrane (BM), and choriocapillaris in the parapapillary region.

Methods

Human eyes enucleated due to uveal melanomas or secondary angle-closure glaucoma were histomorphometrically examined. We compared the tissue dimensions between four groups of eyes categorized based on the presence/absence of high myopia and glaucoma.

Results

The investigation consisted of 100 globes (axial length: 25.6 ± 3.1 mm; range: 20.0-35.0 mm). In non-highly myopic nonglaucomatous eyes, the INL, ONL, RPE, BM, and choriocapillaris ended approximately at the end of the RPE layer, with no significant (all P ≥ 0.10) difference between the layers in their distance to the RPE-layer end. From non-highly myopic nonglaucomatous eyes to non-highly myopic glaucomatous eyes, highly myopic nonglaucomatous eyes, and eventually highly myopic glaucomatous eyes, the choriocapillaris, INL, and ONL increasingly extended into the beta zone, most marked for the choriocapillaris and least marked for the ONL. A larger extension of the choriocapillaris into the parapapillary beta zone correlated with longer axial length (standardized regression coefficient β, 0.24; B, 23.0; 95% confidence interval [CI], 1.6-44.5; P = 0.04) and wider parapapillary beta zone (β, 0.59; B, 0.32; 95% CI, 0.22-0.41; P < 0.001); a larger extension of the INL correlated with longer axial length (β, 0.34; B, 43.7; 95% CI, 11.6-75.7; P = 0.009), longer gamma zone (β, 0.52; B, 0.28; 95% CI, 0.15-0.41; P < 0.001), and diagnosis of non-highly myopic glaucoma (β, 0.28; B, 267; 95% CI, 80.8-454; P = 0.006); and a larger extension of the ONL into parapapillary beta zone correlated with longer axial length (β, 0.50; B, 32.2; 95% CI, 21.6-42.8; P < 0.001) and wider parapapillary beta zone (β, 0.28; B, 0.10; 95% CI, 0.04-0.16; P < 0.001).

Conclusions

Nonglaucomatous non-highly myopic eyes differ from highly myopic eyes and glaucomatous eyes in the spatial relationship of the parapapillary tissue layers.

Myopia: Histology, clinical features, and potential implications for the etiology of axial elongation

Myopic axial elongation is associated with various non-pathological changes. These include a decrease in photoreceptor cell and retinal pigment epithelium (RPE) cell density and retinal layer thickness, mainly in the retro-equatorial to equatorial regions; choroidal and scleral thinning pronounced at the posterior pole and least marked at the ora serrata; and a shift in Bruch's membrane opening (BMO) occurring in moderately myopic eyes and typically in the temporal/inferior direction. The BMO shift leads to an overhang of Bruch's membrane (BM) into the nasal intrapapillary compartment and BM absence in the temporal region (i.e., parapapillary gamma zone), optic disc ovalization due to shortening of the ophthalmoscopically visible horizontal disc diameter, fovea-optic disc distance elongation, reduction in angle kappa, and straightening/stretching of the papillomacular retinal blood vessels and retinal nerve fibers. Highly myopic eyes additionally show an enlargement of all layers of the optic nerve canal, elongation and thinning of the lamina cribrosa, peripapillary scleral flange (i.e., parapapillary delta zone) and peripapillary choroidal border tissue, and development of circular parapapillary beta, gamma, and delta zone. Pathological features of high myopia include development of macular linear RPE defects (lacquer cracks), which widen to round RPE defects (patchy atrophies) with central BM defects, macular neovascularization, myopic macular retinoschisis, and glaucomatous/glaucoma-like and non-glaucomatous optic neuropathy. BM thickness is unrelated to axial length. Including the change in eye shape from a sphere in emmetropia to a prolate (rotational) ellipsoid in myopia, the features may be explained by a primary BM enlargement in the retro-equatorial/equatorial region leading to axial elongation.

Myopic Versus Glaucomatous Parapapillary Beta Zone in Myopic Eyes Versus Eyes With Secondary Angle-Closure Glaucoma

Purpose

To search for histologic differences in the beta zone between myopic eyes versus eyes with secondary angle-closure glaucoma.

Methods

The histomorphometric study consisted of human eyes enucleated due to uveal melanomas or secondary angle-closure glaucoma.

Results

The study included 100 eyes (age: 62.1 ± 15.1 years; axial length: 25.6 ± 3.1 mm; range: 20.0-35.0 mm). In non-highly myopic glaucomatous eyes compared with non-highly myopic nonglaucomatous eyes, the parapapillary alpha zone was longer (223 ± 168 µm vs. 125 ± 128 µm; P = 0.03), beta zone prevalence (15/20 vs. 6/41; P < 0.001) and length (277 ± 245 µm vs. 44 ± 150 µm; P = 0.001) were higher, and RPE cell density in the alpha zone and alpha zone border was lower (all P < 0.05). In highly myopic nonglaucomatous eyes compared with non-highly myopic glaucomatous eyes, parapapillary RPE drusen prevalence (2/19 vs. 10/10; P = 0.01) and alpha zone prevalence (2/19 vs. 16/20; P < 0.001) and length (23 ± 68 µm vs. 223 ± 168 µm; P < 0.001) were lower. In non-highly myopic glaucomatous eyes, Bruch's membrane (BM) thickness decreased (P < 0.001) from the beta zone (6.0 ± 3.1 µm) to the alpha zone (5.1 ± 4.3 µm) and peripheral to it (3.0 ± 0.9 µm). In highly myopic nonglaucomatous eyes, BM thickness did not differ (P > 0.10) between all three regions. In the total study population, RPE cell density in the alpha zone (24.5 ± 9.3 cells/240 µm) was higher than at the alpha zone border (19.2 ± 4.8 cells/240 µm; P < 0.001) or peripheral to it (19.0 ± 3.6 cells/240 µm; P < 0.001).

Conclusions

The glaucomatous beta zone in eyes with chronic angle-closure glaucoma (with the alpha zone, parapapillary RPE drusen, thickened BM, and higher RPE cell count in the adjacent alpha zone) differs histologically from the myopic beta zone (characterized by the absence of the alpha zone and parapapillary RPE drusen, unremarkable BM thickness, and unremarkable parapapillary RPE). The differences suggest different etiologies of the glaucomatous versus myopic beta zone.

Change in the ophthalmoscopical optic disc size and shape in a 10-year follow-up: the Beijing Eye Study 2001-2011

BACKGROUND

To assess prevalence and associated factors of changes in the ophthalmoscopic optic disc size and shape.

METHODS

The case-control study included all highly myopic eyes (myopic refractive error ≤-6.0 diopters) and a randomly selected group of non-highly myopic eyes, examined in the population-based Beijing Eye Study 2001 and 2011.

RESULTS

The study included 89 highly myopic eyes (age:65.0±9.8 years) and 86 non-highly myopic eyes. Reduction in ophthalmoscopic disc size (prevalence, high myopia: 30 (33.7%) eyes; non-high myopia: 7 (8.1%) eyes) was associated with non-circular gamma zone enlargement (OR: 19.4; 95% CI: 6.7 to 56.6; p<0.001) and disc-fovea line elongation (OR: 2.80;95% CI: 1.12 to 6.98; p=0.03). Disc size reduction was correlated with a disc diameter shortening in direction of the widest gamma zone enlargement (correlation coefficient r=34; p=0.01). The perpendicular disc diameter remained mostly unchanged, resulting in an ovalisation of the ophthalmoscopic disc shape. Enlargement of the ophthalmoscopic disc size (prevalence, high myopia: 22 (24.7%) eyes; non-high myopia: 4 (4.7%) eyes) was associated with circular gamma zone enlargement (4.99; 95% CI: 1.95 to 12.8; p=0.001) and high myopia (OR: 4.29; 95% CI: 1.34 to 13.8; p=0.01).

CONCLUSIONS

Myopic axial elongation may lead first to a Bruch's membrane (BM) opening (BMO) shift into the foveal direction leading to BM overhanging into the nasal intrapapillary compartment, development and enlargement of gamma zone at the temporal disc side, reduction in the ophthalmoscopically visible disc area and ovalisation of the ophthalmoscopic disc shape. In a second step, an axial elongation-associated BMO enlargement may lead to a circular gamma zone increase and, due to the retraction of BM at the nasal disc border, to an enlargement of the ophthalmoscopically visible optic disc.

Parapapillary gamma zone enlargement in a 10-year follow-up: the Beijing Eye Study 2001-2011

PURPOSE

To assess prevalence and associated factors of parapapillary gamma zone enlargement (GZE).

METHODS

Using fundus photographs and optical coherence tomographic images of participants of the population-based Beijing Eye Study, we examined gamma zone changes in a 10-year follow-up.

RESULTS

The study included 89 highly myopic eyes (61 participants; age: 65.0 ± 9.8 years) and 86 randomly selected non-highly myopic eyes. GZE prevalence was significantly higher in highly myopic eyes than non-highly myopic eyes (75/89; 84%; 95% CI: 77, 92 versus 18/86; 21%; 95% CI:12, 30; p < 0.001). None of the eyes showed a reduction in gamma zone size. Higher prevalence of segmental GZE without enlargement of Bruch's membrane opening (BMO) (mean: 26/175; 14.9%; 95% CI: 9.5, 20.2) was associated with optic disc size reduction (OR: 43.3; 95% CI: 10.9, 172; p < 0.001), disc-fovea distance elongation (OR: 15.4; 95% CI: 3.12, 76.4; p = 0.001) and lower prevalence of high axial myopia (OR: 0.08; 95% CI: 0.01, 0.44; p = 0.001). Higher prevalence of circular GZE (mean: 38/175; 21.7%; 95% CI: 16, 28) was correlated with optic disc enlargement (OR: 4.30; 95% CI: 1.58, 11.7; p = 0.004), and higher prevalence of myopic maculopathy progression (OR: 4.04; 95% CI: 1.60, 10.2; p = 0.003), or alternatively, higher prevalence of high myopia (OR: 4.44; 95% CI: 1.76, 11.2; p = 0.002). Circular GZE or BMO enlargement was associated with lower prevalence of macular BM defect enlargement (p = 0.035). GZE occurred perpendicular to the orientation of myopic lacquer cracks in 12 out of 17 (71%; 95% CI: 46, 95) eyes with lacquer cracks. Segmental GZE occurred in 49 (89%) out of 55 eyes in the same direction as shortening of the disc diameter developed.

CONCLUSIONS

The observations support the possibility of a posterior myopic axial elongation-associated BMO shift, leading to a segmental GZE in non-highly myopic eyes, followed by a circular GZE in highly myopic eyes. Large gamma zone might be protective against macular Bruch's membrane defects.

Myopic macular Bruch's membrane defects

Purpose

To examine histologic characteristics of macular Bruchś membrane defects (BMD) in axially elongated eyes.

Design

Histomorphometric study.

Methods

Using light microscopy, we examined enucleated human globes for BMDs.

Results

In 247 eyes, BMDs were detected in 15 (6.1%) eyes (axial length:27.0-36.0 mm), in 10 of them in the macular region. Prevalence and size of BMDs (mean:1.93 ± 1.62 mm; range:0.22mm-6.24 mm) correlated with longer axial length (OR:1.52; 95%CI:1.19,1.94; P = 0.001) and higher prevalence of scleral staphylomas (OR:16.3; 95%CI:2.67,99.3; P < 0.001). The BMDs were smaller than corresponding gaps in the retinal pigment epithelium (RPE) (1.93 ± 1.62 mm versus 2.61 mm ± 1.73 mm; P = 0.003), and larger than corresponding gaps in the inner nuclear layer (0.43 ± 0.76 mm; P = 0.008) and inner limiting membrane bridges (0.13 ± 0.33 mm; P = 0.001). Choriocapillaris thickness, BM thickness and RPE cell density did not vary (all P > 0.05) between the BDM border and adjacent areas. In the BMD, choriocapillaris and RPE were absent. The sclera was thinner in the BDM area than in adjacent areas (0.28 ± 0.19 mm versus 0.36 ± 0.13 mm; P = 0.006).

Conclusions

BMDs as hallmarks of myopic macular degeneration are characterized by longer gaps in the RPE and smaller gaps in the outer nuclear layer and inner nuclear layer, by localized scleral thinning, and by a spatial association with scleral staphylomas. Thickness of the choriocapillaris and density of the RPE cell layer, both absent within the BDMs, do not vary between the BMD border and adjacent regions. The results suggest an association between BDMs and absolute scotomas, stretching of the adjacent retinal nerve fiver layer, and an axial elongation-associated stretching effect on BM as etiology of the BDMs.

Inner limiting membrane bridges within Bruch's membrane defects in pathological myopia

The purpose of the study was to examine peculiarities of the inner limiting membrane (ILM) in axially elongated eyes. The histomorphometric study included human globes enucleated due to reasons such as painful secondary angle-closure glaucoma or malignant uveal melanomas. Using light microscopy, we searched for regions with ILM-specific features in association with a marked axial elongation. Out of 279 eyes (279 patients) (mean age: 61.8 ± 13.9 years; axial length: 25.5 ± 3.1 mm (range: 20.0-37.0 mm)), two eyes (axial length: 30 mm and 34 mm, respectively) showed one region and two regions, respectively, characterized by ILM presence and absence of all other retinal layers, retinal pigment epithelium, Bruch´s membrane (BM) and choroid. The length of these regions, called ILM-bridges, was 1.06 mm, 0.73 mm, and 0.62 mm, respectively. All ILM-bridges were spatially associated with a larger, underlying BM defect and with localized scleral thinning without a staphylomatous scleral configuration. The distance between the ILM-bridges and the optic disc ranged between 1.92 mm and 4.21 mm. In univariable analysis, ILM-bridge number increased with longer axial length (beta: 0.19; P = 0.002) and higher BM defect prevalence (beta: 0.21; P = 0.001), while in multivariable analysis, the ILM-bridges number remained to be significantly correlated only with a higher prevalence of BM defect (beta: 0.15; P = 0.048). ILM-bridges occur in eyes with pathologic myopia in spatial association with underlying, larger BM defects. They may be due to an axial elongation-associated local stretching and rupture of all other retinal layers, caused by the BM defect-related enlargement of the retinal undersurface. Future studies may explore whether these histologic observations support the notion of the ILM having a relatively high biomechanical strength against myopic stretching-associated forces.

Photoreceptor density in relation to axial length and retinal location in human eyes

The purpose of the study was to examine the density of retinal photoreceptors and retinal pigment epithelium (RPE) cells in relation to myopic axial elongation in human eyes. Using light microscopy, we assessed the density of photoreceptors and RPE cells at the ora serrata, equator, and midperiphery (equator/posterior pole midpoint), and the RPE cell density additionally at the posterior pole, in enucleated human globes. The study included 78 eyes (mean age: 59.2 ± 15.6 years; range: 32-85 years) with a mean axial length of 27.3 ± 3.6 mm (range: 21.5-37.0 mm). Close to the ora serrata, at the equator and midperiphery, photoreceptor and RPE cell density was 246 ± 183, 605 ± 299 and 1089 ± 441 photoreceptors/mm and 56.1 ± 13.7, 45.2 ± 15.1, and 48.8 ± 15.6 RPE cells/mm, respectively. Densities of both cell types in all three regions were positively correlated with each other (all P < 0.001) and decreased with longer axial length (all P < 0.001) and longer distance between the ora serrata and the posterior pole (all P < 0.001), most marked at the midperiphery and least marked close to the ora serrata. The PRE cell density at the posterior pole was not significantly (P = 0.35) related to axial length. The photoreceptor density at the ora serrata (beta:- 0.33) and equator (beta: - 0.27) and RPE cell density at the ora serrata (beta: - 0.27) decreased additionally with the presence of glaucoma. The findings suggest that the axial elongation-related decrease in photoreceptor and RPE cell density is most marked at the midperiphery, followed by the equator and finally the ora serrata region. It suggests that the axial elongation-related enlargement of the eye wall predominantly takes place in the retro-equatorial region, followed by the equatorial region.

Elongation of the Retina and Ciliary Body in Dependence of the Sagittal Eye Diameter

Purpose

To examine the elongation of the retina and ciliary body in relation to myopic axial elongation.

Methods

Using light microscopy, we histomorphometrically measured in enucleated human globes the length of the retina from the ora serrata to the optic disc borders. The total retinal length was the mean of the retinal length measurements obtained on both sides of the optic disc. We additionally determined the length of the ciliary body between the ora serrata and the scleral spur.

Results

The study included 174 eyes (mean age, 61.7 ± 14.8 years; range, 24-89 years) with a mean sagittal eye diameter of 25.9 ± 3.2 mm (range, 21.0-37.0 mm). Retinal length (beta, 0.81; nonstandardized regression coefficient B, 0.73; 95% confidence interval (CI), 0.65-0.81; P < 0.001) and ciliary body length elongated (beta, 0.49; nonstandardized regression coefficient B, 0.16; 95% CI, 0.12-0.20; P < 0.001) with a longer sagittal eye diameter. Retinal length and ciliary body length were associated with each other (beta, 0.34; nonstandardized regression coefficient B, 0.12; 95% CI, 0.07-0.17).

Conclusions

The retina elongates by 0.73 mm (95% CI, 0.65-0.81) and the ciliary body by 0.16 mm (95% CI, 0.12-0.20) for each millimeter of axial elongation. With the inner limiting membrane and retinal nerve fibers forming the only structures connecting the deeper retinal layers with the optic disc, retinal elongation may be associated with a stretching of the retinal nerve fibers, potentially leading to optic nerve damage in highly myopic eyes, and with an increased strain within the inner limiting membrane, potentially leading to an intraretinal elevation at the posterior pole with the sequel of a myopic maculoschisis.

Progression and associated factors of lacquer cracks/patchy atrophies in high myopia: the Beijing Eye Study 2001-2011

PURPOSE

To assess the development and progression of lacquer cracks/patchy atrophies (LCs/PAs) in high myopia.

METHODS

The case control study included highly myopic eyes (refractive error ≤  - 6.0 diopters), examined in the population-based Beijing Eye Study 2001/2011. Using fundus photographs taken in 2001 and 2011 and optical coherence tomographic images obtained in 2011, we assessed the incidence and enlargement of pre-existing LC/PAs.

RESULTS

The study included 89 highly myopic eyes (age: 65.0 ± 9.4 years). Newly developed or enlarged LC/PAs were detected in 17 (19.1%; 95% confidence interval (CI): 11.0, 27.0) eyes, with a new LC development without previous LCs, enlargement of a pre-existing LC, LC enlargement to a PA, development of a new PA without any previous LCs, and enlargement of a pre-existing PA detected in 3, 3, 5, 3, and 3 eyes, respectively. In 14 (82.4%; 95%CI: 62.3, 100) of the 17 eyes with LC/PA development or enlargement, the LC/PAs elongated perpendicularly to, and widened in, the direction of gamma zone enlargement. Higher prevalence of LC/PA enlargement was associated (multivariable analysis) with higher myopic maculopathy stage in 2001 (odds ratio (OR): 7.83; 95%CI: 2.65, 23.2; P < 0.001) and higher frequency of parapapillary delta zone enlargement (OR: 32.0; 95%CI: 3.07, 334; P < 0.001). Prevalence of LC/PA enlargement was lower than the prevalence of changes in other myopic maculopathy features (disc-fovea distance elongation: 71%; choroidal vessel shift: 55%; reduction in ophthalmoscopical disc size: 34%; ophthalmoscopic disc size enlargement: 25%). All eyes with LC/PA enlargement showed a pre-existing and enlarging gamma zone.

CONCLUSIONS

Development and enlargement of LC/PAs were associated with enlargement of parapapillary delta zone and often occurred in association with the direction of gamma zone enlargement.

Histopathology of myopic cobblestones

PURPOSE

To search for the histological correlate of peripheral 'cobblestones' in highly myopic eyes.

METHODS

The histomorphometric investigation included histologic sections of enucleated eyes of Caucasian patients. Using light microscopy, we measured the thickness of the retina, Bruch's membrane (BM) and choriocapillaris.

RESULTS

The study included 50 eyes (mean age:60.6 ± 18.7 years;axial length:26.5 ± 3.8 mm), with cobblestone regions detected in 7 eyes. BM thickness and choriocapillaris thickness in the cobblestone region were thinner (1.1 ± 0.2 µm versus 2.4 ± 0.8 µm; p < 0.001 and 1.6 ± 0.5 µm versus 2.6 ± 1.9 µm; p = 0.02, respectively), and just outside of the cobblestone region they were thicker (3.3 ± 0.6 µm versus 2.4 ± 0.8 µm; p = 0.005 and 5.7 ± 1.6 µm versus 2.6 ± 1.9 µm; p = 0.002, respectively) than in corresponding regions of eyes without cobblestones. Within the group of eyes with cobblestones, BM thickness (1.1 ± 0.2 mm versus 3.3 ± 0.6 mm; p < 0.001), choriocapillaris thickness (1.6 ± 0.5 mm versus 5.7 ± 1.6 mm; p < 0.001) and choriocapillaris density (48±15 µm/300 µm versus 159 ± 66 µm/300 µm;PP=0.002) were significantly lower in the cobblestone region than just outside of the cobblestone region. The cobblestone regions were characterized by firm adhesion of disorganized retina with thinned BM, few retinal pigment epithelium (RPE) islands within cobblestone regions, and absence of regional scleral or overall choroidal thinning. BM was mono-layered within, and double-layered outside of cobblestone regions, with the inner layer missing within the cobblestone region (except for the RPE islands).

CONCLUSIONS

Peripheral cobblestone regions in highly myopic eyes are characterized by marked BM thinning with absence of an inner BM layer, almost complete RPE absence, choriocapillaris thinning and firm connection of a disorganized retina to BM. These findings may help elucidating the process of axial elongation in myopic eyes.

Retinal nerve fibre layer thickness in association with gamma zone width and disc-fovea distance

PURPOSE

Previous studies have shown that the retinal nerve fibre layer (RNFL) thickness as surrogate of the optic nerve decreases with longer axial length. We explored which explanatory parameters might explain that association.

METHODS

Participants of the population-based Beijing Eye Study 2011 without any retinal or optic nerve disease were selected based on a refractive error-based stratified randomization.

RESULTS

The study included of 632 participants (age: 59.1 ± 7.3 years; axial length: 23.5 ± 1.2 mm; range: 20.88-28.68 mm). Thicker RNFL (mean: 101.0 ± 10.0 μm) was associated (multivariable analysis) with smaller parapapillary gamma zone (defined as Bruch's membrane-free parapapillary region) (standardized regression coefficient beta: -0.13; non-stadardized regression coefficient B: -0.008; 95% confidence interval (CI): -0.014, -0.003; p = 0.005) and shorter disc-fovea distance (beta: -0.15; B: -3.91; 95% CI: -6.60; -1.22; p = 0.004), after adjusting for age (beta: -0.22; B: -030; 95% CI: -0.41, -0.19; p < 0.001), gender (beta: 0.12; B: 2.37; 95% CI 0.77, 3.97; p = 0.004) and larger optic disc area (beta: 0.12; B: 0.12; 95% CI: 2.14; 95% CI: 0.54, 3.73; p = 0.009). RNFL thickness decreased by 8 μm (95% CI: 3, 14) for each mm increase in gamma zone width, and by 3.91 μm (95% CI: 1.22, 6.60) for each mm elongation of the disc-fovea distance. If disc-fovea distance and gamma zone width were replaced by axial length, the latter was correlated with RNFL thickness (beta: -0.37; B: -3.12; 95% CI: -3.88, -2.35; p < 0.001). Longer disc-fovea distance was directly associated with larger gamma zone (beta: 0.50; B: p < 0.001).

CONCLUSIONS

The RNFL thickness decrease with longer axial length is associated with a longer optic disc-fovea distance and larger parapapillary gamma zone. Longer disc-fovea distance and larger gamma zone lead to an elongation and stretching of the retinal nerve fibres, potentially causing a thinning or loss of the nerve fibres. It may explain the occurrence of visual field defects in some non-glaucomatous highly myopic eyes without macular correlates of the perimetric defects.

Decreasing myopic lacquer crack and widening parapapillary gamma zone: case report

Background

Myopic axial elongation may be due to an equatorial enlargement of Bruch’s membrane (BM), leading to a prolate eye shape and increasing strain with BM and the retinal pigment epithelium (RPE) layer at the posterior pole. The increased BM strain may cause an enlargement of Bruch’s membrane opening (BMO) of the optic nerve head, with the subsequent development and enlargement of parapapillary gamma zone as BM-free parapapillary zone. The increased strain within BM and RPE may also cause lacquer cracks (LCs) as linear breaks in the RPE and / or BM. Studies suggested that a more marked gamma zone enlargement is associated with lower prevalence of LCs or macular BM defects. Here report on the disappearance of a LC during a 10-year follow-up of a highly myopic eye, concurrent with a marked increase in gamma zone.

Case presentation

A 56-year-old woman showed in her right eye (axial length measured 30.69 mm) a LC, vertically oval optic disc, and parapapillary gamma zone in 2001. When re-examined in 2006, gamma zone had enlarged, while the LC was no longer detectable. In 2011, the LC was not visible neither upon ophthalmoscopy and or upon optical coherence tomography (OCT), while gamma zone had further enlarged. The gamma zone enlargement occurred in a direction perpendicular to the direction of the former LC.

Conclusions

The observation suggest that a LC can decrease in width, in temporal association with an enlargement of gamma zone. It fits with the notion that an enlargement of the BMO (i.e., enlarging gamma zone) may lead to a relaxation of the BM strain and subsequently to a decrease in the width of the LC.

Histology of neovascular myopic macular degeneration

To assess the histological correlate of neovascular or exudative myopic macular degeneration (nMMD) in highly myopic human eyes, we examined histomorphometrically histologic sections of enucleated eyes of Caucasian patients. The study included 284 eyes (age: 61.9 ± 13.7 years; range: 24–89 years; axial length: 25.5 ± 3.1 mm; range: 20–37 mm). An nMMD was detected in 5 eyes (axial length: 29.6 ± 2.6 mm; range: 26.0–31.0 mm). All these eyes showed within or close to the nMMD a macular Bruch’s membrane (BM) defect, fibrous tissue with erythrocyte-filled blood vessels, and proliferations of irregularly pigmented and irregularly piled-up retinal pigment epithelium (RPE) cells each of which was connected with a curled-up, PAS (Periodic-Acid-Shiff)-positive membrane. The nMMD lesions were covered by proliferated RPE cells. RPE cells were not detected within the retina. In binary regression analysis, a higher nMMD prevalence was associated with a higher prevalence of macular BM defects (odds ratio: > 1000; P < 0.001), while the association with axial length was not significant (P = 0.43) in that model. After adjustment for the presence of macular BM defects, the nMMD prevalence was not associated with BM thickness (measured at the posterior pole, equator-posterior pole midpoint, equator and shortly posterior to the ora serrata) (P = 0.10; P = 0.87; P = 0.40; and P = 0.36, respectively), RPE cell layer thickness (P = 0.83; P = 0.79; P = 0.31; P = 0.38, resp.), RPE cell density (P = 0.56; P = 0.91; P = 0.47; P = 0.87, resp.), choriocapillaris thickness (P = 0.47; P = 0.93; P = 0.41; P = 0.75, resp.), and choriocapillaris density (P = 0.99; P = 0.94; P = 0.17; P = 0.97, resp.). The results suggest that nMMD is characterized by a fibrous pseudo-metaplasia of the RPE and is strongly associated with macular BM defects, without other detected histomorphometric differences in thickness or density of the RPE, BM, and choriocapillaris.

Choroidal shift in myopic eyes in the 10-year follow-up Beijing eye study

The aim of the study was to assess longitudinal changes in the spatial relationship of the choroidal vasculature to retinal vasculature in myopic eyes. In the population-based longitudinal Beijing Eye Study in 2001/2011, we examined all highly myopic eyes with assessable fundus photographs and a randomized group of non-highly myopic. Using fundus photographs, we qualitatively assessed changes in the location of major choroidal vessels in relationship to retinal vessels. The study consisted of 85 highly myopic eyes (58 participants;age:64.8 ± 9.4 years) and 85 randomly selected non-highly myopic eyes. A choroidal shift in relationship to the retinal vessels was detected more often in the highly myopic group than the non-highly myopic group (47/85 (55%) vs 6/85 (7%); P < 0.001). In the highly myopic group, the choroidal vessel shift occurring on the disc-fovea line in 39 (44%) eyes, was similar to, or smaller than, the enlargement in gamma zone width in 26 (67%) eyes and in 11 (28%) eyes respectively. The choroidal vessel shift was larger (P = 0.002) in eyes without choroidal vessels in gamma zone than in eyes with large choroidal vessels in gamma zone. In 14 (17%) eyes, a localized centrifugal choroidal shift was observed in association with an increase in the stage of myopic maculopathy. The results suggest that highly myopic eyes show a change in the position of large choroidal vessels in relationship to retinal vessels, in association with development or enlargement of gamma zone and an increase in the stage of myopic maculopathy.

Location of Parapapillary Gamma Zone and Vertical Fovea Location. The Beijing Eye Study 2011

Purpose

To assess the spatial relationship between the locations of the parapapillary gamma zone and the fovea.

Methods

In a non-glaucomatous subgroup of the population-based Beijing Eye Study population, we measured the mean angle between the optic disc–fovea line and the horizontal (disc–fovea angle), the vertical distance of the fovea from the horizontal through the optic disc center (fovea vertical distance), and the location and width of the widest part of parapapillary gamma zone.

Results

The study included 203 individuals (203 eyes; mean axial length, 24.4 ± 1.5 mm; range, 22.03–28.87 mm). The widest gamma zone part was located most often temporal horizontally (51.7%), then inferiorly (43.8%), superiorly (2.5%), and nasally (2.0%). The disc–fovea angle (mean, 7.50° ± 4.00°; range, –6.30° to –23.25°) was significantly higher (P = 0.003; i.e., fovea located more inferiorly) in eyes with the widest gamma zone inferiorly (8.46° ± 4.37°) than in eyes with the widest gamma zone temporally (6.71° ± 3.46°) and in eyes with the widest gamma zone temporally, superiorly, or nasally combined (6.75° ± 3.53°; P = 0.003). The fovea vertical distance (mean, 0.65 ± 0.33 mm; range, –0.20 to 1.67 mm) was longer (P = 0.001; i.e., fovea located more inferiorly) in eyes with the widest gamma zone inferiorly (0.73 ± 0.33 mm) than in eyes with the widest gamma zone temporally (0.58 ± 0.30 mm) and in eyes with a temporal, superior, or nasal gamma zone combined (0.58 ± 0.31 mm; P = 0.001). The fovea vertical distance increased (multivariate analysis) with the widest gamma zone location inferiorly (β = 0.25; P = 0.001) and wider width of the gamma zone (β = 0.19; P = 0.01).

Conclusions

An inferior fovea location is associated with a wider inferior gamma zone and vice versa, supporting the notion of an inferior shifting of Bruch's membrane as the cause for an inferior gamma zone.

Neural Network-Based Retinal Nerve Fiber Layer Profile Compensation for Glaucoma Diagnosis in Myopia: Model Development and Validation

Background

Due to the axial elongation–associated changes in the optic nerve and retina in high myopia, traditional methods like optic disc evaluation and visual field are not able to correctly differentiate glaucomatous lesions. It has been clinically challenging to detect glaucoma in highly myopic eyes.

Objective

This study aimed to develop a neural network to adjust for the dependence of the peripapillary retinal nerve fiber layer (RNFL) thickness (RNFLT) profile on age, gender, and ocular biometric parameters and to evaluate the network’s performance for glaucoma diagnosis, especially in high myopia.

Methods

RNFLT with 768 points on the circumferential 3.4-mm scan was measured using spectral-domain optical coherence tomography. A fully connected network and a radial basis function network were trained for vertical (scaling) and horizontal (shift) transformation of the RNFLT profile with adjustment for age, axial length (AL), disc-fovea angle, and distance in a test group of 2223 nonglaucomatous eyes. The performance of RNFLT compensation was evaluated in an independent group of 254 glaucoma patients and 254 nonglaucomatous participants.

Results

By applying the RNFL compensation algorithm, the area under the receiver operating characteristic curve for detecting glaucoma increased from 0.70 to 0.84, from 0.75 to 0.89, from 0.77 to 0.89, and from 0.78 to 0.87 for eyes in the highest 10% percentile subgroup of the AL distribution (mean 26.0, SD 0.9 mm), highest 20% percentile subgroup of the AL distribution (mean 25.3, SD 1.0 mm), highest 30% percentile subgroup of the AL distribution (mean 24.9, SD 1.0 mm), and any AL (mean 23.5, SD 1.2 mm), respectively, in comparison with unadjusted RNFLT. The difference between uncompensated and compensated RNFLT values increased with longer axial length, with enlargement of 19.8%, 18.9%, 16.2%, and 11.3% in the highest 10% percentile subgroup, highest 20% percentile subgroup, highest 30% percentile subgroup, and all eyes, respectively.

Conclusions

In a population-based study sample, an algorithm-based adjustment for age, gender, and ocular biometric parameters improved the diagnostic precision of the RNFLT profile for glaucoma detection particularly in myopic and highly myopic eyes.

Elongation of the disc-fovea distance and retinal vessel straightening in high myopia in a 10-year follow-up of the Beijing eye study

To assess changes in the disc-fovea distance (DFD) in highly myopic eyes in a 10-year population-based follow-up study. The case control study included all highly myopic eyes (myopic refractive error ≥ − 6.0 diopters or axial length ≥ 26.0 mm) and a randomized group of non-highly myopic eyes examined in the population-based Beijing Eye Study 2001 and 2011. Using fundus photographs and optical coherence tomographic images, we assessed changes in DFD, parapapillary gamma zone, angle kappa (angle between the temporal arterial arcades), and course of papillo-macular retinal vessels. The study included 89 highly myopic eyes and 86 non-highly myopic eyes. DFD elongation, gamma zone widening, angle kappa decrease and straightening of papillo-macular retinal vessels were detected more often (all P < 0.001) in the highly myopic group than in the non-highly myopic group (63/89 versus 9/86;75/89 versus 18/86;61/89 versus 9/86; and 58/89 versus 7/86,respectively). Gamma zone enlargement, angle kappa reduction and papillo-macular retinal vessel straightening were significantly (all P < 0.001) associated with DFD elongation. The length of macular Bruch’s membrane on the disc-fovea line and the vertical distance between the temporal arterial arcade did not change during follow-up. DFD elongation (10-year incidence 70.8% in highly myopic eyes) was associated with gamma zone enlargement, while macular Bruch’s membrane length remained unchanged. It supports the notion of a temporal shift of an otherwise stable posterior Bruch’s membrane in axially elongated eyes. Straightening of the papillo-macular vessels with increasing gamma zone width suggests a coincident stretching of the papillo-macular retinal nerve fibers and inner limiting membrane.

Peaks of circumpapillary retinal nerve fibre layer and associations in healthy eyes: the Beijing Eye Study 2011

AIMS

To investigate the distribution and associations of the circumpapillary retinal nerve fibre layer thickness (RNFLT) profile, characterised as peak height and peak position, in healthy eyes.

METHODS

667 healthy participants (294 male) were randomly selected from the Beijing Eye Study 2011. RNFLT was measured at 768 points at 3.4 mm circumpapillary position using spectral-domain optical coherence tomography (OCT). The location and height of the superior temporally peak (Peak^ST), superior nasal peak (Peak^SN) and inferior temporal peak (Peak^IT) were assessed.

RESULTS

The RNFLT was thickest at Peak^IT (194±25 µm; location: 288±12°), followed by Peak^ST (182±25 µm; 73±10°) and Peak^SN (125±23 µm; 135°±13°). In multivariable analysis, peak RNFLT decreased with longer axial length (p<0.001; correlation coefficient beta: -0.18 to -0.15; all peaks), older age (all p<0.01, beta: -0.10; Peak^ST and Peak^IT), female gender (p=0.026, beta: -0.09; Peak^ST), and larger parapapillary gamma zone and beta zone width (p≤0.004, beta: -0.16 to-0.11; Peak^SN). The temporal peaks were located more closely to the horizontal line in women (p≤0.020, beta: 0.09-0.11) and with longer axial length (p<0.001, beta: 0.27-0.31), while they were located more inferiorly in eyes with larger Bruch's membrane openings (BMOs) (p≤0.01, beta:0.10~0.11).

CONCLUSIONS

Peak RNFLT decreased by 0.34 µm for each increase of year in age (Peak^ST and Peak^IT), by 3.2-3.5 µm for each 1 mm increase in axial length (all three peaks), and was 4.5 µm thinner in women than in men. The position of temporal peaks depended on gender, axial length and BMO diameter. These associations should be taken into count in OCT-based RNFLT assessment for disease finding, especially in glaucoma evaluation.

Peripapillary border tissue of the choroid and peripapillary scleral flange in human eyes

PURPOSE

To assess dimensions and associations of the peripapillary border tissue of the choroid (PBT-C) and peripapillary scleral flange (PBT-S).

METHODS

The histomorphometric investigation included histological sections of enucleated eyes of Caucasian patients. Using light microscopy, the PBT dimensions were measured.

RESULTS

The study included 85 eyes (85 patients) with an age of 62.0 years (14.1 years) (mean (SD)) (range:37-87 years) and mean axial length of 26.7 mm (3.5 mm) (range:21.0-37.0 mm). Thicker PBT-C thickness (mean: 68.8 μm (35.7 μm)) was associated with shorter axial length (p < 0.001; standardized regression coefficient beta: -0.50), and longer PBT-C length (mean: 531 μm (802 μm)) was correlated with longer axial length (p < 0.001;beta:0.66). PBT-C cross-sectional area (mean 17 050 μm² (10 420 μm² )) was not significantly associated with axial length (p = 0.37). Decreasing with longer axial length (p < 0.001;beta:0.64), the angle between PBT-C and Bruch's membrane was approximately 90° in non-highly myopic eyes without overhanging Bruch's membrane (BM), it ranged between 100° and 180° in eyes with BM overhanging into the intrapapillary region, and it was close to 0° in eyes with parapapillary gamma zone. Thicker thickness of PBT-S (mean:83 μm (21 μm)) was correlated with presence of glaucoma (p = 0.02). Optic nerve pia mater thickness (mean:109 μm (44 μm)) increased with glaucoma presence (p = 0.046;beta:0.31) but not with axial length (p = 0.34).

CONCLUSIONS

Peripapillary border tissue of the choroid (PBT-C) and PBT-S as continuation of the optic nerve pia mater are distinct structures, with PBT-C remodelling during myopic axial elongation and PBT-S being mostly independent of axial elongation. PBT-C and PBT-S may be of importance for the optic nerve head biomechanics and PBT-C for separation of the choroidal space from the intrapapillary compartment.

Corrugated Bruch's membrane in high myopia

PURPOSE

To assess the appearance of Bruch's membrane (BM) in axially elongated eyes.

METHODS

The light-microscopical investigation included histological anterior-posterior sections of human eyes. Using a light microscope, we assessed whether BM in the posterior segment was straight or locally corrugated. Corrugation of BM was defined as an elevation of BM with a height >20 μm over a basis of 50 μm without collateral proliferations of retinal pigment epithelium or choroidal swelling.

RESULTS

The investigation included 85 eyes (age: 62.0 ± 14.1 years; axial length: 26.7 ± 3.5 mm). In multivariate analysis, the presence of a corrugated BM, detected in eight eyes (9.4%), was strongly associated with the presence of macular BM defects [p = 0.001; odds ratio (OR): 418; 95% confidence interval (CI): 1 215 000], but not with axial length (p = 0.54). Bruch's membrane (BM) corrugation was detected in seven (54%) of 13 eyes with macular BM defects. The single eye with BM corrugation and without macular BM defect showed the corrugated BM located in the parapapillary region at the peripheral end of a large parapapillary gamma zone.

CONCLUSION

Bruch's membrane (BM) corrugation can be present in the vicinity of macular BM defects in highly myopic eyes, perhaps due to differences in the tension within BM in various regions at the margin of the BM defect. Bruch's membrane (BM) corrugation may also develop at the papillary end of BM in eyes with a large parapapillary gamma zone, potentially due to a disinsertion of BM at the end of the peripapillary choroidal border tissue of Jacoby. The observation of BM corrugation may help elucidating the aetiology of axial myopia.

Optimal Timing of Pulmonary Banding for Newborns with Single Ventricle Physiology and Unrestricted Pulmonary Blood Flow

The aim of this study was to determine the optimal timing of pulmonary artery band (PAB) placement in neonates with single ventricle physiology, unrestricted pulmonary blood flow, and no systemic outflow tract obstruction. Retrospective chart review of all patients who underwent isolated PAB for single ventricle physiology between January 2005 and December 2014 was carried out. The influence of age at the time of PAB on operative mortality, the need for reoperation to adjust the PAB, the preparedness of the pulmonary vascular bed prior to the second-stage bidirectional cavopulmonary shunt (BCPS), and the outcomes following BCPS were studied. The study cohort included 54 subjects (34 males). The median age at the time of PAB was 18 days. The overall mortality following PAB was 4 % (2/54). Reoperation for PAB adjustment was 7 % (4/54). Younger age at the time of PAB was not associated with mortality or increased risk of reoperation. There was a mild positive correlation between the age at PAB and the mean pulmonary artery pressure prior to BCPS. There was also a weak positive correlation between the age at PAB and the duration of ventilation following BCPS. Age at the time of PAB did not influence pulmonary vascular resistance (PVR) prior to BCPS or the mortality and hospital stay following BCPS. PAB can be done safely and effectively soon after birth in neonates with single ventricle physiology, increased pulmonary blood flow, and no potential or actual systemic outflow tract obstruction. It may not be necessary to wait for a few weeks after birth for the neonatal PVR to fall before placing a PAB.

Optic Disc - Fovea Angle: The Beijing Eye Study 2011

Purpose

To determine the optic disc-fovea angle (defined as angle between the horizontal and the line between the optic disc center and the fovea) and to assess its relationships with ocular and systemic parameters.

Methods

The population-based cross-sectional Beijing Eye Study 2011 included 3468 individuals. A detailed ophthalmic examination was carried out. Using fundus photographs, we measured the disc-fovea angle.

Results

Readable fundus photographs were available for 6043 eyes of 3052 (88.0%) individuals with a mean age of 63.6±9.3 years (range: 50–91 years) and a mean axial length of 23.2±1.0 mm (range: 18.96–28.87 mm). Mean disc-fovea angle was 7.76 ± 3.63° (median: 7.65°; range: -6.3° to 28.9°). The mean inter-eye difference was 4.01 ± 2.94° (median: 3.49°; range: 0.00–22.3°). In multivariate analysis, larger disc-fovea angle was associated (regression coefficient r²: 0.08) with older age (P = 0.009; standardized regression coefficient beta: 0.05), thinner RNFL in the nasal superior sector (P<0.001; beta: -0.17), superior sector (P<0.001; beta: -0.10) and temporal superior sector (P<0.001; beta: -0.11) and thicker RNFL in the inferior sector (P<001; beta: 0.13), nasal inferior sector (P<001; beta: 0.13) and nasal sector (P = 0.007; beta: 0.06), higher prevalence of retinal vein occlusion (P = 0.02; beta: 0.04), and with larger cylindrical refractive error (P = 0.04; beta: 0.04).

Conclusions

The optic disc-fovea angle markedly influences the regional distribution of the RNFL thickness pattern. The disc-fovea angle may routinely be taken into account in the morphological glaucoma diagnosis and in the assessment of structure-function relationship in optic nerve diseases. Future studies may address potential associations between a larger disc-fovea angle and retinal vein occlusions and between the disc-fovea angle and the neuroretinal rim shape.

Splitting blood and blood product packaging reduces donor exposure for patients undergoing cardiopulmonary bypass

BACKGROUND

Cardiopulmonary bypass for congenital heart surgery requires packed red cells (PRBC) and fresh frozen plasma (FFP) to be available, both for priming of the circuit as well as to replace blood loss. This study examines the hypothesis that splitting one unit of packed red blood cells and one unit of fresh frozen plasma into two half units reduces blood product exposure and wastage in the Operating Room.

METHODS

Beginning August 2013, the blood bank at Children's National Medical Center began splitting one unit of packed red blood cells (PRBC) and one unit of fresh frozen plasma (FFP) for patients undergoing cardiopulmonary bypass (CPB). The 283 patients who utilized CPB during calendar year 2013 were divided into 2 study groups: before the split and after the split. The principal endpoints were blood product usage and donor exposure intra-operatively and within 72 hours post-operatively.

RESULTS

There was a significant decrease in median total donor exposures for FFP and cryoprecipitate from 5 to 4 per case (p = 0.007, Mann-Whitney U-test). However, there was no difference in the volume of blood and blood products used; in fact, there was a significant increase in the amount of FFP that was wasted with the switch to splitting the unit of FFP.

CONCLUSIONS

We found that modification of blood product packaging can decrease donor exposure. Future investigation is needed as to how to modify packaging to minimize wastage.

Parapapillary atrophy: histological gamma zone and delta zone

Background

To examine histomorphometrically the parapapillary region in human eyes.

Methodology/Principal Findings

The histomorphometric study included 65 human globes (axial length:21–37 mm). On anterior-posterior histological sections, we measured the distance Bruch's membrane end (BME)-optic nerve margin (“Gamma zone”), BME-retinal pigment epithelium (RPE) (“Beta zone”), BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. “Delta zone” was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm) was significantly (P = 0.01) larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28) associated with axial length. Beta zone was significantly (P = 0.004) larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm) was associated with axial length (P<0.001;r² = 0.73) with an increase starting at an axial length of 26.5 mm. It was not significantly (P = 0.24) associated with glaucomatous optic neuropathy. Delta zone (present only in eyes with axial length of ≥27 mm) was associated with axial length (P = 0.001) and scleral flange length (P<0.001) but not with glaucoma (P = 0.73).

Conclusions/Significance

Parapapillary gamma zone (peripapillary sclera without overlying choroid, Bruch's membrane and deep retinal layers) was related with axial globe elongation and was independent of glaucoma. Delta zone (no blood vessels >50 µm diameter within gamma zone) was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch's membrane without RPE) was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

The spider effect: morphological and orienting classification of microglia in response to stimuli in vivo

The different morphological stages of microglial activation have not yet been described in detail. We transected the olfactory bulb of rats and examined the activation of the microglial system histologically. Six stages of bidirectional microglial activation (A) and deactivation (R) were observed: from stage 1A to 6A, the cell body size increased, the cell process number decreased, and the cell processes retracted and thickened, orienting toward the direction of the injury site; until stage 6A, when all processes disappeared. In contrast, in deactivation stages 6R to 1R, the microglia returned to the original site exhibiting a stepwise retransformation to the original morphology. Thin highly branched processes re-formed in stage 1R, similar to those in stage 1A. This reverse transformation mirrored the forward transformation except in stages 6R to 1R: cells showed multiple nuclei which were slowly absorbed. Our findings support a morphologically defined stepwise activation and deactivation of microglia cells.

Histology of the parapapillary region in high myopia

PURPOSE

To examine histomorphometrically the parapapillary region in highly myopic eyes.

DESIGN

Retrospective laboratory investigation.

METHODS

We examined a highly myopic glaucomatous group (36 human globes; axial length >26.5 mm) and a non-highly myopic group (28 globes with secondary angle-closure glaucoma; 17 eyes with malignant choroidal melanoma). Using light microscopy, pupil-optic nerve sections were assessed.

RESULTS

The length of the scleral flange (sclera between optic nerve border and optic nerve dura mater) increased with axial length (P < .001; correlation coefficient r = 0.70) and decreased with its thickness (P < .001; r = 0.75). In all highly myopic eyes (n = 15) with a distance of >0.5 mm between optic nerve border and beginning of Bruch membrane, the parapapillary region consisted of an elongated parapapillary scleral flange associated with a scleral flange thinning and a retrobulbar cerebrospinal fluid space extended into the retroparapapillary region. The parapapillary retina was composed of retinal nerve fiber layer (or its remnants) only, without elements of any other retinal layer, without underlying Bruch membrane or choroid. These histologic features were not detected in any of the non-highly myopic eyes.

CONCLUSIONS

Since parapapillary scleral thickness influences the lamina cribrosa biomechanics, the findings may partially explain the increased glaucoma susceptibility in highly myopic eyes. The implications of an absence of Bruch membrane and choroid in the highly myopic parapapillary region, and the implications of the retrobulbar parapapillary extension of the cerebrospinal spinal fluid space for the pathophysiology of the optic nerve head, have to be elucidated.

Postoperative complications following the Fontan procedure: the role of aprotinin

OBJECTIVE

To determine how the anti-inflammatory properties of aprotinin impact on postoperative complications in children undergoing the Fontan procedure.

METHODS

We included all patients between 14 months and 18 years (n=56) undergoing a Fontan operation at our institution between January 2005 and June 2009. The study group (n=29) included patients from January 2005 through December 2007 all of whom received aprotinin. The control group (n=27) included all patients from January 2008 through June 2009 who did not receive aprotinin. We reviewed all medical records and collected preoperative, intraoperative and postoperative data. Duration and volume of chest tube drainage were the primary outcome measures.

RESULTS

Of the 20% of patients who had postoperative arrhythmias, multivariate logistic regression analysis demonstrated only aprotinin was associated with significantly decreased postoperative arrhythmias (P=0.01). Renal function and fenestration or Fontan thrombosis did not differ significantly; there was no statistically significant difference in volume or duration of chest tube drainage. Median duration of chest tube drainage was 7 days in the aprotinin group and 8 days for patients who did not receive aprotinin (P=0.36).

CONCLUSION

The anti-inflammatory properties of aprotinin may be protective against postoperative arrhythmias. Aprotinin does not confer increased risks of prolonged chest tube drainage, renal dysfunction or thrombosis in patients undergoing the Fontan procedure.

Aprotinin protects the cerebral microcirculation during cardiopulmonary bypass

BACKGROUND AND OBJECTIVE

We have previously reported that administration of aprotinin at a single dose protects the cerebral microcirculation. The current study was designed to identify the optimal dose for protecting the cerebral microcirculation with assessment of neurological and behavioral recovery as well as renal function after circulatory arrest and ultra-low-flow bypass.

METHODS

Twenty-four piglets were randomly assigned to three bypass groups at risk for postoperative cerebral and renal dysfunction. Cerebral microcirculation was assessed by intravital microscopy. Rhodamine-stained leukocytes were observed for adhesion and rolling. Animals were randomized to one of four aprotinin doses. Neurological deficit score, histological score, creatinine and blood urea nitrogen were analyzed, both independently for this study as well as in combination with 50 animals who were studied with the same protocol and near-infrared spectroscopy.

RESULTS

There was a dose-dependent relationship, resulting in fewer activated rolling leukocytes with a higher aprotinin dose. Aprotinin dose was an independent predictor of more rapid recovery of neurological and behavioral outcome. We present a linear regression model where aprotinin dose predicts neurological score. Aprotinin had no impact on renal function.

CONCLUSIONS

Aprotinin reduces cerebral leukocyte activation and accelerates neurologic recovery in a dose-dependent fashion. Aprotinin has no measurable impact on standard indices of renal function in young piglets. The current lack of availability of aprotinin is a serious disadvantage for pediatric patients undergoing cardiopulmonary bypass.

Aprotinin concentration varies significantly according to cardiopulmonary bypass conditions

Although aprotinin is partially excreted unchanged in the urine, its primary site of metabolism is in the renal lysosomes following proximal tubule resorption. This study tested the hypothesis that plasma aprotinin concentration varies with cardiopulmonary bypass conditions. Thirty-two piglets (weight 13.2 +/- 1.9 kg) received an aprotinin initial dose of 30,000 KIU/kg, a maintenance infusion of 10,000 KIU/kg/h, with a cardiopulmonary bypass (CPB) prime of 30,000 KIU/kg. Aprotinin infusion was terminated at the end of CPB and stopped during hypothermic circulatory arrest (HCA). Piglets were randomized to four groups (n = 8 per group): HCA, 60-minute period at 15 degrees C; low-flow (LF), 10 mL/kg/min low-flow CPB at 25 degrees C; full flow (FF), full flow CPB at 37 degrees C; control at 37 degrees C without CPB. Blood samples were collected at 7 time points: after induction of anesthesia (baseline), after initial dose, 10, 50 and 115 min after start of CPB, just before end of CPB and 30 min after CPB. Plasma aprotinin levels were determined by modified functional assays. Aprotinin levels in the control group were significantly lower at each point after start of CPB than all groups with CPB (p < .001). In particular, during the reperfusion period, aprotinin levels were higher in HCA and LF groups than FF group (p < .05). Throughout CPB, aprotinin levels in the HCA group remained unchanged (p > .40). Bypass conditions affect plasma aprotinin concentration. Recently reported renal and neurological complications with aprotinin use during CPB may reflect excessive dosing and point to the need for real-time monitoring.

Resection of an obstructive neonatal cardiac myxoma of the infundibulum

Myxoma, the most common primary cardiac tumor in adults, is rare in neonates. We describe a myxoma arising from the infundibulum of the right ventricle causing significant outflow tract obstruction in an otherwise normal newborn. Serial echocardiograms revealed an increasing gradient across the right ventricular outflow tract prompting surgery. The patient underwent successful excision of the myxoma with an uneventful recovery.

Cardiac surgery and neurological injury in children

The freedom of children from vascular disease makes them an ideal population in which to study the deleterious effects of cardiopulmonary bypass. Cerebral embolic injury arises intraoperatively from air in the cardiac chambers and monitoring lines, particularly those in the left atrium. Postoperative emboli are more common in patients with single ventricle physiology, especially following a bidirectional Glenn shunt or Fontan procedure. Poor cannula selection or placement during bypass can cause maldistribution of the perfusate and cerebral injury. Postoperative hyperthermia can cause brain damage. Results of prospective and retrospective studies of neurological and developmental outcome after paediatric cardiac surgery at the Children's Hospital, Boston, have led to the following inferences: the use of circulatory arrest should be minimised; the pH stat strategy is preferred for cardiopulmonary bypass over the alpha stat strategy. A higher haematocrit on bypass, for example 30%, may be preferable to 20%; postoperative fever should be strenuously avoided. Surgeons should be aware that cardiopulmonary bypass parameters can have subtle but important effects on late developmental outcome.

Management of transposition of the great arteries with single coronary artery

Approximately 5% of patients with transposition of the great arteries have a single coronary artery. In the early years of the arterial switch procedure a single coronary artery was associated with an increased risk of mortality. This was particularly true for the most common type of single coronary artery in which there is a right posterior ostium giving rise to a right coronary artery that passes to the right atrioventricular groove and a left coronary artery that passes posterior to the pulmonary artery. An understanding of the mechanisms by which this coronary pattern increases the risk of mortality has led to neutralization of this risk factor. The risk of late reintervention after an arterial switch with single coronary artery is increased with a single left posterior ostium with the right coronary passing anterior to the aorta. The mechanism remains unclear.

General health status of children with D-transposition of the great arteries after the arterial switch operation

BACKGROUND

To study the long-term impact on general health status of D-transposition of the great arteries (D-TGA) after the arterial switch operation (ASO) during infancy, we asked parents to complete the Child Health Questionnaire, Parent Form-50 when their children were 8 years old.

METHODS AND RESULTS

Of 160 eligible patients, questionnaires were completed for 155 subjects (96%). Median age at surgery was 6 days (range 1 to 67 days), and median age at completion of the Child Health Questionnaire was 8.1 years (7.6 to 10.0 years). Subsequent to questionnaire completion, children underwent psychometric testing. Mean Physical Health Summary and Psychosocial Summary scores were 54.0+/-6.1 and 49.7+/-9.9, respectively, which were similar to those of normal subjects. Compared with the normative sample, parents of D-TGA patients reported more problems with attention, learning, and speech, as well as greater frequency of developmental delay (P<0.001 for each). Worse Psychosocial Summary scores were significantly associated with lower full-scale IQ (P=0.001) and lower achievement in reading (P=0.005) and math (P=0.007). Worse Physical Health Summary scores were associated with longer hospital stay after the ASO (P=0.02). General health status scores were not significantly related to presence of ventricular septal defect, age at surgery, perfusion variables during the ASO, sex, or history of cardiac reoperation.

CONCLUSIONS

At age 8 years, children with D-TGA after ASO have an overall physical and psychosocial health status similar to that of the general population. Lower IQ and academic achievement are associated with worse psychosocial health status, whereas longer hospital course after initial surgery is associated with worse physical health status.

Effects of hematocrit on cerebral microcirculation and tissue oxygenation during deep hypothermic bypass

BACKGROUND

One rationale for hemodilution during hypothermic cardiopulmonary bypass (CPB) has been improved microcirculation. However, the optimal degree of hemodilution remains unclear. We therefore studied cerebral microcirculation and tissue oxygenation in a new intravital microscopic model at 3 different hematocrit (Hct) values.

METHODS AND RESULTS

Three groups of 5 piglets with a cranial window over the parietal cortex underwent cooling at Hct of 10%, 20%, or 30%, followed by 1-hour deep hypothermic circulatory arrest (DHCA) and rewarming on CPB. For assessment of functional capillary density (FCD), plasma was labeled with fluorescein-isothiocyanate-dextran. Rhodamine-stained leukocytes were observed in postcapillary venules with analysis for adhesion and rolling. NADH, a natural intracellular fluorophore that increases during ischemia, was measured densitometrically during bypass and DHCA. FCD did not significantly differ from baseline during cooling in any group. However, during early reperfusion (5 minutes) after DHCA, the FCD was significantly higher in the Hct 30% group than in the Hct 10% group. Leukocyte adherence decreased in all groups during CPB and was only moderately increased at the end of the experiment. However, severe hemodilution (Hct 10%) was associated with a significantly greater number of rolling leukocytes relative to Hct 30%.

CONCLUSIONS

Higher Hct does not impair cerebral microcirculation and reduces white cell/endothelial activation after deep hypothermic bypass and circulatory arrest. Severe hemodilution (Hct 10%) results in evidence of inadequate cerebral tissue oxygenation during the cooling phase of CPB. This study suggests that Hct of 30% is preferable relative to lower Hct values during hypothermic CPB, particularly if DHCA is used.