Bruch's Membrane Thickness Research Articles

Cholesterol Accumulation Promotes Photoreceptor Senescence and Retinal Degeneration.

Dysregulated cholesterol metabolism is critical in the pathogenesis of AMD. Cellular senescence contributes to the development of numerous age-associated diseases. In this study, we investigated the link between cholesterol burden and the cellular senescence of photoreceptors. Retinas from rod-specific ATP binding cassette subfamily A member 1 (Abca1) and G member 1 (Abcg1) (Abca1/g1-rod/-rod) knockout mice fed with a high-fat diet were analyzed for the signs of cellular senescence. Real-time quantitative PCR and immunofluorescence were used to characterize the senescence profile of the retina and cholesterol-treated photoreceptor cell line (661W). Inducible elimination of p16(Ink4a)-positive senescent cells (INK-ATTAC) mice or the administration of senolytic drugs (dasatinib and quercetin: D&Q) were used to examine the impact of senolytics on AMD-like phenotypes in Abca1/g1-rod/-rod retina. Increased accumulation of senescent cells as measured by markers of cellular senescence was found in Abca1/g1-rod/-rod retina. Exogenous cholesterol also induced cellular senescence in 661W cells. Selective elimination of senescent cells in Abca1/g1-rod/-rod;INK-ATTAC mice or by administration of D&Q improved visual function, lipid accumulation in retinal pigment epithelium, and Bruch's membrane thickening. Cholesterol accumulation promotes cellular senescence in photoreceptors. Eliminating senescent photoreceptors improves visual function in a model of retinal neurodegeneration, and senotherapy offers a novel therapeutic avenue for further investigation.

Drusen in the macula and parapapillary region.

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. We histomorphometrically examined human eyes enucleated due to uveal melanomas or secondary angle-closure glaucoma. The study included 106 eyes (age, 62.6 ± 15.2years) 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 ± 10.1µm versus 34.3 ± 19.8µm; P = 0.003), while both groups did not differ significantly in basal drusen width (74.0 ± 36.3µm versus 108.7 ± 101.0µm; P = 0.95). Eyes with macular drusen and eyes without drusen did not differ significantly in BM thickness (2.74 ± 0.44µm versus 2.55 ± 0.88µm; P = 0.57) or in RPE cell density (35.4 ± 10.4 cells/480µm versus 32.8 ± 7.5 cells/480µm; P = 0.53), neither in the drusen region nor in the drusen vicinity, while BM thickness (4.60 ± 1.490µm; P < 0.001) and RPE cell density (56.9 ± 26.8 cells/480µm; 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. 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.

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

Aims/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 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% versus 29.0 ± 18.4%; p &lt; 0.001). At the LPCM end, BM was in direct contact with 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 &lt; 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 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.

Clinical and histological characteristics of axial myopia

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 fibres. 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.

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.

To search for histologic differences in the beta zone between myopic eyes versus eyes with secondary angle-closure glaucoma. The histomorphometric study consisted of human eyes enucleated due to uveal melanomas or secondary angle-closure glaucoma. 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). 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.

IMI-Nonpathological Human Ocular Tissue Changes With Axial Myopia.

To describe nonpathological myopia-related characteristics of the human eye. Based on histomorphometric and clinical studies, qualitative and quantitative findings associated with myopic axial elongation are presented. In axial myopia, the eye changes from a spherical shape to a prolate ellipsoid, photoreceptor, and retinal pigment epithelium cell density and total retinal thickness decrease, most marked in the retroequatorial region, followed by the equator. The choroid and sclera are thin, most markedly at the posterior pole and least markedly at the ora serrata. The sclera undergoes alterations in fibroblast activity, changes in extracellular matrix content, and remodeling. Bruch's membrane (BM) thickness is unrelated to axial length, although the BM volume increases. In moderate myopia, the BM opening shifts, usually toward the fovea, leading to the BM overhanging into the nasal intrapapillary compartment. Subsequently, the BM is absent in the temporal region (such as parapapillary gamma zone), the optic disc takes on a vertically oval shape, the fovea-optic disc distance elongates without macular BM elongation, the angle kappa reduces, and the papillomacular retinal vessels and nerve fibers straighten and stretch. In high myopia, the BM opening and the optic disc enlarge, the lamina cribrosa, the peripapillary scleral flange (such as parapapillary delta zone) and the peripapillary choroidal border tissue lengthen and thin, and a circular gamma and delta zone develop. A thorough characterization of ocular changes in nonpathological myopia are of importance to better understand the mechanisms of myopic axial elongation, pathological structural changes, and psychophysical sequelae of myopia on visual function.

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

To examine Bruch's membrane (BM) in association with the longitudinal part of the ciliary muscle (LPCM) in the pars plana region. Using light microscopy, we histomorphometrically assessed BM and the LPCM in the pars plana region. 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). 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.

Intravitreal panitumumab for prevention of myopic axial elongation in highly myopic adult eyes with myopic macular degeneration: Phase 1 study on safety

AbstractPurpose: Recent histomorphometric and clinical studies suggested that axial myopic elongation occurs through an enlargement of Bruch's membrane (BM) in the retroequatorial and equatorial region, leading to a thinning of choroid and sclera at the posterior pole. Thickness of the retina and choriocapillaris and RPE‐density in the macular region and BM thickness in any region remain independent of axial length. The equatorial‐to‐retroequatorial BM enlargement may be caused by an epidermal growth factor (EGF)‐associated RPE activity. Experimental studies in guinea pigs and monkeys showed a reduction in axial elongation by intravitreally applied blockers of EGF family members and the EGF receptor, and an increase in axial elongation by intravitreally applied EGF family members. In a clinical study, the intraocular EGF amount correlated with longer axial length. It led to the hypothesis, that ocular axial elongation is associated with EGF, and that further axial elongation may be prevented by an EGF blockade. We examined here the safety of intravitreally applied panitumumab, an EGF receptor blocker, already in clinical systemic use in oncology for two decades.Methods: The phase‐1 study included highly myopic adult patients with myopic macular degeneration. The eyes received one to two intravitreal injections of 0.6 mg (60 μl), 1.2 mg (120 μl) or 1.8 mg (180 μl) panitumumab.Results: The study included 10 patients (age 57–72 years, axial length: 29.10 mm–32.67 mm). Examined at day 1, 7, and 28 and at 2 and 3 months after the injections, the injected eyes did not show any intraocular inflammation or morphologic or functional changes, assessed by retinal electroretinography, perimetry, optical coherence tomography, tonometry and visual acuity measurement.Conclusions: The preliminary observations of these 10 patients are in agreement with a notion of an intraocular tolerability of panitumumab repeatedly injected intravitreally in doses of 0.6, 1.2 or 1.8 mg.

Characterization and identification of measurable endpoints in a mouse model featuring age-related retinal pathologies: a platform to test therapies

AbstractApolipoprotein B100 (apoB100) is the structural protein of cholesterol carriers including low-density lipoproteins. It is a constituent of sub-retinal pigment epithelial (sub-RPE) deposits and pro-atherogenic plaques, hallmarks of early dry age-related macular degeneration (AMD), an ocular neurodegenerative blinding disease, and cardiovascular disease, respectively. Herein, we characterized the retinal pathology of transgenic mice expressing mouse apoB100 in order to catalog their functional and morphological ocular phenotypes as a function of age and establish measurable endpoints for their use as a mouse model to test potential therapies. ApoB100 mice were found to exhibit an age-related decline in retinal function, as measured by electroretinogram (ERG) recordings of their scotopic a-wave, scotopic b-wave; and c-wave amplitudes. ApoB100 mice also displayed a buildup of the cholesterol carrier, apolipoprotein E (apoE) within and below the supporting extracellular matrix, Bruch's membrane (BrM), along with BrM thickening, and accumulation of thin diffuse electron-dense sub-RPE deposits, the severity of which increased with age. Moreover, the combination of apoB100 and advanced age were found to be associated with RPE morphological changes and the presence of sub-retinal immune cells as visualized in RPE-choroid flatmounts. Finally, aged apoB100 mice showed higher levels of circulating and ocular pro-inflammatory cytokines, supporting a link between age and increased local and systemic inflammation. Collectively, the data support the use of aged apoB100 mice as a platform to evaluate potential therapies for retinal degeneration, specifically drugs intended to target removal of lipids from Bruch's membrane and/or alleviate ocular inflammation.

SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY DETECTION OF BRUCH MEMBRANE AND CHORIOCAPILLARIS ABNORMALITIES IN SORSBY MACULAR DYSTROPHY.

Swept-source optical coherence tomography angiography (SS-OCTA) was used to analyze Bruch membrane (BM) and choriocapillaris (CC) abnormalities in undiagnosed family members with Sorsby macular dystrophy (SMD). In a family with SMD ( TIMP3 Tyr191Cys), SS-OCTA imaging was performed using the 6 × 6 mm scan patter and previously validated algorithms to detect abnormalities in BM and the CC, as well as the presence of reticular pseudodrusen and macular neovascularization. Genetic analyses were performed for TIMP3 mutations. Of eight family members, two were previously diagnosed with SMD and six were asymptomatic. SS-OCTA imaging of the 33-year-old proband revealed type 1 macular neovascularization in the left eye and bilateral reticular pseudodrusen, thickening of BM, CC thinning, and increases in CC flow deficits. A TIMP3 mutation was confirmed. His niece, despite having no clinical evidence of SMD, showed BM thickening and CC thinning on SS-OCTA. A TIMP3 mutation was confirmed. The proband's younger nephew and niece also carried the TIMP3 mutation without clinical evidence of SMD. Two additional members had normal examinations, unremarkable SS-OCTA findings, and no TIMP3 mutation. Swept-source optical coherence tomography angiography imaging can detect BM and CC abnormalities in vivo in subjects unaware of their TIMP3 status in a family with SMD.

Functional Correlates of Outer Retina Remodeling in Intermediate Age-Related Macular Degeneration Using Microperimetry.

PurposeTo assess the effect of drusen morphometric changes and choroidal vascular modifications on retinal sensitivity (RS) evaluated through microperimetry in intermediate age-related macular degeneration (iAMD).MethodsA retrospective review of 18 iAMD patients (18 eyes) with a 12-month follow-up was performed. Eye-tracked spectral-domain optical coherence tomography was obtained, with automatic segmentation of the outer retinal layer (ORL) delineating the drusen area from the external limiting membrane to Bruch's membrane and outer nuclear layer (ONL) thickness maps adjusted manually, as needed. Advanced retinal pigment epithelium analysis was also performed with a ZEISS PLEX Elite 900. Microperimetry obtained under mesopic conditions was overlaid with the corresponding thickness maps with Fiji software. The choroidal vascularity index (CVI) was calculated in the subfoveal b-scan and volumetric in the central 1-mm subfield.ResultsA reduced central ONL thickness was strongly associated with RS decline at the same region (r = 0.69, P = 0.002) and globally (r = 0.80, P < 0.001) at baseline, but also at 1 year in the central subfield (central: r = 0.70, P = 0.001). One-year subfoveal CVI variation, differently from volumetric CVI, directly influenced the central (r = 0.64, P = 0.004) and global RS (r = 0.59, P = 0.009), indicating that a CVI reduction negatively affected RS. A greater volumetric CVI within central 1-mm was associated with ORL thickening at 1 year (r = 0.61, P = 0.008).ConclusionsProgressive degeneration of the ONL is related to irreversible photoreceptor dysfunction in iAMD. Likewise, choroidal vascular modifications are associated with a significant functional decline in the central region and diffusely.

A Multiscale drusen growth model for Age‐related Macular Degeneration

AbstractAge‐related macular degeneration (AMD) is the leading cause of vision loss in older adults above the age of 50. AMD is attributed to the degeneration and loss of normal function of the outer retina in the macular region. Presence of extracellular material called drusen between the Bruch's membrane (BrM) and the retinal pigment epithelium (RPE) is the hallmark of AMD. Moreover, thickening and reduced diffusivity of the BrM has been observed in patients with AMD. In this paper, we develop a mulitscale Drusen growth model to test the hypothesis that the BrM thickening and Drusen generation could be a coupled process such that the BrM thickening causes hypoxic stress at RPE which leads to generation of more drusen at POS and vice versa. The proposed framework comprises of a cascade lattice micromechanics model for characterizing the overall diffusivity of the BrM, a finite element model for simulating oxygen transport from the vascular system to the photoreceptors and a cellular potts model for simulating morphological changes to the outer retina due to drusen development. Simulation results are analysed at different time steps and implications of the potential chain reaction on Drusen growth and RPE, POS cell deterioration are discussed.

AICAR upregulates ABCA1/ABCG1 expression in the retinal pigment epithelium and reduces Bruch's membrane lipid deposit in ApoE deficient mice

The etiology of age-related macular degeneration (AMD) is diverse; however, recent evidence suggests that the lipid metabolism-cholesterol pathway might be associated with the pathophysiology of AMD. The ATP-binding cassette (ABC) transporters, ABCA1 and ABCG1, are essential for the formation of high-density lipoprotein (HDL) and the regulation of macrophage cholesterol efflux. The failure of retinal or retinal pigment epithelium (RPE) cholesterol efflux to remove excess intracellular lipids causes morphological and functional damage to the retina. In this study, we investigated whether treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMP-activated protein kinase (AMPK) activator, improves RPE cholesterol efflux and Bruch's membrane (BM) lipid deposits. The protein and mRNA levels of ABCA1 and ABCG1 in ARPE-19 cells and retinal and RPE/choroid tissue from apolipoprotein E-deficient (ApoE-/-) mice were evaluated after 24 weeks of AICAR treatment. The cholesterol efflux capacity of ARPE-19 cells and the cholesterol-accepting capacity of apoB-depleted serum from mice were measured. The thickness of the BM and the degree of lipid deposition were evaluated using electron microscopy. AICAR treatment increased the phosphorylation of AMPK and the protein and mRNA expression of ABCA1 and ABCG1 in vitro. It promoted cholesterol efflux from ARPE-19 cells and upregulated the protein and mRNA levels of ABCA1 and ABCG1 in the retina and RPE in vivo. ApoB-depleted serum from the AICAR-treated group showed enhanced cholesterol-accepting capacity. Long-term treatment with AICAR reduced BM thickening and lipid deposition in ApoE-/- mice. In conclusion, AICAR treatment increased the expression of lipid transporters in the retina and RPE in vivo, facilitated intracellular cholesterol efflux from the RPE in vitro, and improved the functionality of HDL to accept cholesterol effluxed from the cell, possibly via AMPK activation. Collectively, these effects might contribute to the improvement of early age-related pathologic changes in the BM. Pharmacological improvement of RPE cholesterol efflux via AMPK activation may be a potential treatment strategy for AMD.

Zonular defects in loxl1-deficient zebrafish.

To investigate the roles of the lysyl oxidase-like 1 (loxl1) gene in zebrafish eye development and the potency of loxl1 deficiency in mimicking the ocular manifestations of exfoliation syndrome (XFS). CRISPR/Cas9 technology was used to generate a frameshift coding deletion in zebrafish loxl1. Expression profiles and ocular manifestations of the wildtype, heterozygous mutant (loxl1+/- ) and homozygous mutant (loxl1-/- ) zebrafish were analysed in a range of developmental stages from zebrafish larvae to dissected adult zebrafish eyes. The loxl1 deficiency caused zonular bundling disorders in juvenile zebrafish and accumulation of pearl-like particles adhering to the adult zebrafish zonule. The bundles appeared to lack form and were thinner in both loxl1+/- and loxl1-/- zebrafish compared with the wildtype (p < 0.01 for all Bonferroni post-hoc analyses). The zonule of loxl1-/- zebrafish appeared stretched, ragged and torn, with isolated fibres also detected. The particles in loxl1-/- zebrafish were more numerous (counts: 92.33 ± 10.02/100 μm2 vs. 58.33 ± 5.03/100 μm2 , p=0.006), but smaller in size (diameter: 0.21 ± 0.03 μm vs. 0.43 ± 0.04 μm, p=0.002) compared with those in loxl1+/- . Transmission electron microscopy revealed thinning or even loss of elastic lamina in loxl1+/- Bruch's membrane (BM) (thickness of elastic lamina: 92.94 ± 18.19 nm in the wildtype vs 35.65 ± 14.76 nm in loxl1+/- , p=0.003). The breakage of BM was observed in loxl1-/- . The loxl1-/- zebrafish is a promising animal model of XFS zonular pathology.

Histopathology of myopic cobblestones.

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

Characterization of age-related macular degeneration in Indian donor eyes.

Purpose:The purpose of this study was to test the reliability of fundus stereomicroscopy in postmortem eyes to assign severity of age-related macular degeneration (AMD) using the Minnesota grading and confirmation by histology using Alabama and Sarks grading scales and to assess the incidence of AMD pathology in donor eyes from a South Indian population.Methods:Eyes (199) from 153 donors (55–95 years) after obtaining fundus images were processed for histology. Fundus images were graded according to the Minnesota grading system based on drusen size, area of depigmentation, and atrophy. At least one eye from each donor displaying the AMD phenotypes were subjected to histological examination. The fundus grading was correlated with histology and the stages of AMD assigned for early AMD by the Alabama AMD grading system and for both early and advanced AMD by the Sarks classification.Results:Stereoscopic examination of the fundus found that 10 of the 153 donors had features of early AMD and 3 advanced AMD. Following histological examination, one of the early AMD eyes was reclassified as advanced AMD. Early AMD features that were observed on histology included soft drusen (>63 μm), basal laminar deposits, photoreceptor outer segment degeneration, disorganization of retinal pigment epithelium (RPE), Bruch's membrane thickening. Advanced AMD features observed in histology are extensive atrophy of RPE, choroidal neovascularization and disciform scar formation.Conclusion:Identification of either early or advanced AMD using stereomicroscopic assessment (SMA) showed high sensitivity and specificity. However, misclassification between AMD stages can occur when only SMA is used.

This issue of ACTA, printed and electronic

This issue of ACTA, printed and electronic

Histology of myopic posterior scleral staphylomas.

Since histomorphometric descriptions of posterior scleral staphylomas, although forming a major part of myopic maculopathy, have been scarce so far, we histomorphometrically examined scleral staphylomas in enucleated human eyes. Using light microscopy, we histomorphometrically examined sagittal histological sections of human globes enucleated due to malignant choroidal melanomas or secondary angle-closure glaucoma. Out of 246 globes included into the study, posterior scleral staphylomas were detected in 10 eyes (mean length: 31.4±3.0mm; range: 28.0-37.0mm). In the staphylomatous region in the study group as compared with the corresponding region of a control group adjusted for age and axial length, scleral thickness was significantly lower (109±25µm versus 319±161µm; p=0.001). The study group in the staphylomatous region as compared to the highly myopic control group in the corresponding region did not differ significantly in retinal pigment epithelium (RPE) cell density (19.6±4.9 cells/300µm versus 21.1±5.7 cells/300µm; p=0.84) and RPE height (8.2±2.8µm versus 6.1±2.5µm; p=0.13), Bruch's membrane (BM) thickness (3.5±1.3µm versus 4.2±2.3µm; p=0.40) and choriocapillaris thickness (5.3±2.8µm versus 4.4±2.8µm; p=0.49) and density (164±99µm versus 226±38µm; p=0.13). All staphylomatous regions showed a localized BM defect. Marked scleral thinning and spatially correlated BM defects histologically characterized myopic scleral staphylomas, while thickness and density of the choriocapillaris and RPE and BM thickness did not differ significantly between staphylomatous versus non-staphylomatous eyes in the respective regions. These findings support the notion that a locally reduced scleral resistance against a backward pushing BM led to a local scleral outpouching. The outpouching-associated increase in curvature length may stretch BM with the sequel of a localized BM rupture.

Selective Retina Therapy Reduces Bruch's Membrane Thickness and Retinal Pigment Epithelium Pathology in Age-Related Macular Degeneration Mouse Models.

PurposeTo investigate the effect of selective retina therapy (SRT) on age-related macular degeneration (AMD)-like alterations of retinal pigment epithelium (RPE) and Bruch's membrane (BrM) in AMD mouse models as therapeutic approach for the treatment of dry AMD.MethodsIn B6.129P2-Apoetm1Unc/J (ApoE−/−) and B6.129X1-Nfe2I2tm1Ywk/J (NRF2−/−), one randomized eye of each mouse in groups of 15 mice was treated by SRT (532 nm, 300 ms, ∼1.4-μs pulse, 100 Hz, 50-μm spot), the fellow eye and healthy C57BL/6J mice served as controls. Clinical examinations were obtained at treatment day and 1 month later, followed by enucleation to analyze BrM thickness and ultrastructural RPE morphology.ResultsNearly all ApoE−/− and NRF2−/− mice showed AMD-like retinal alterations. BrM thickness was increased in both mouse models, RPE had vacuoles within the cell body and shortened apical microvilli. SRT neither affected neuroretinal anatomy nor function. BrM thickness as well as AMD-like ultrastructural alterations of the RPE were significantly reduced in laser-treated eyes compared with fellow control and untreated control eyes.ConclusionsSRT reduces BrM thickness and AMD-like RPE alterations in AMD mouse models without damage to structural or functional properties of neuroretina. It may be a prophylactic or therapeutic option for dry AMD.Translational RelevanceSRT shows therapeutic effectivity in murine AMD models and might therefore become an option for the treatment of dry AMD.