Review

Authors: Debora L Nickla, Josh Wallman

The choroid of the eye is primarily a vascular structure supplying the outer retina. It has several unusual features: It contains large membrane-lined lacunae, which, at least in birds, function as part of the lymphatic drainage of the eye and which can change their volume dramatically, thereby changing the thickness of the choroid as much as four-fold over a few days (much less in primates). It contains non-vascular smooth muscle cells, especially behind the fovea, the contraction of which may thin the choroid, thereby opposing the thickening caused by expansion of the lacunae. It has intrinsic choroidal neurons, also mostly behind the central retina, which may control these muscles and may modulate choroidal blood flow as well. These neurons receive sympathetic, parasympathetic and nitrergic innervation. The choroid has several functions: Its vasculature is the major supply for the outer retina; impairment of the flow of oxygen from choroid to retina may cause Age-Related Macular Degeneration. The choroidal blood flow, which is as great as in any other organ, may also cool and warm the retina. In addition to its vascular functions, the choroid contains secretory cells, probably involved in modulation of vascularization and in growth of the sclera. Finally, the dramatic changes in choroidal thickness move the retina forward and back, bringing the photoreceptors into the plane of focus, a function demonstrated by the thinning of the choroid that occurs when the focal plane is moved back by the wearing of negative lenses, and, conversely, by the thickening that occurs when positive lenses are worn. In addition to focusing the eye, more slowly than accommodation and more quickly than emmetropization, we argue that the choroidal thickness changes also are correlated with changes in the growth of the sclera, and hence of the eye. Because transient increases in choroidal thickness are followed by a prolonged decrease in synthesis of extracellular matrix molecules and a slowing of ocular elongation, and attempts to decouple the choroidal and scleral changes have largely failed, it seems that the thickening of the choroid may be mechanistically linked to the scleral synthesis of macromolecules, and thus may play an important role in the homeostatic control of eye growth, and, consequently, in the etiology of myopia and hyperopia.

Topics: Animals; Choroid; Humans; Muscle, Smooth; Myopia

PubMed: 20044062
DOI: 10.1016/j.preteyeres.2009.12.002

Review

Authors: Denis Wakefield, Daniel Clarke, Peter McCluskey...

There has been steady progress in understanding the pathogenesis, clinical features, and effective treatment of acute anterior uveitis (AU) over the past 5 years. Large gene wide association studies have confirmed that AU is a polygenic disease, with overlaps with the seronegative arthropathies and inflammatory bowel diseases, associations that have been repeatedly confirmed in clinical studies. The role of the microbiome in AU has received increased research attention, with recent evidence indicating that human leukocyte antigen B27 (HLA B27) may influence the composition of the gut microbiome in experimental animals. Extensive clinical investigations have confirmed the typical features of acute AU (AAU) and its response to topical, regional and systemic immunosuppressive treatment. Increased understanding of the role of cytokines has resulted in studies confirming the value of anti-cytokine therapy [anti-tumor necrosis factor (anti-TNF) and interleukin 6 (IL-6) therapy] in severe and recurrent cases of AAU, particularly in subjects with an associated spondyloarthopathy (SpA) and in juvenile idiopathic arthritis (JIA)-associated AAU.

Topics: Acute Disease; Animals; Bacteria; Cytokines; Gastrointestinal Microbiome; Genetic Predisposition to Disease; HLA-B27 Antigen; Haplotypes; Humans; Immunosuppressive Agents; Intestines; Tumor Necrosis Factor Inhibitors; Uvea; Uveitis, Anterior

PubMed: 33469457
DOI: 10.3389/fimmu.2020.608134

Review

Authors: Swapnil Parchand, Deepshikha Agrawal, Nikitha Ayyadurai...

Sympathetic ophthalmia is a rare, bilateral, granulomatous, panuveitis following penetrating trauma or surgery to one eye. Clinical presentation commonly occurs within the first year of trauma occurrence but can be delayed by several years. It manifests as acute/chronic granulomatous uveitis with yellowish-white choroidal lesions or Dalen-Fuchs nodules. Initially, patients respond rapidly to corticosteroid therapy, but a majority require long-term use of corticosteroid-sparing agents to prevent recurrences. The purpose of this review is to elaborate on the current understanding of the pathophysiology, the importance of multimodal imaging in early diagnosis, and the role of newer immunomodulatory and biological agents in recalcitrant cases.

Topics: Adrenal Cortex Hormones; Choroid; Humans; Ophthalmia, Sympathetic

PubMed: 35647958
DOI: 10.4103/ijo.IJO_2363_21

Review

Authors: Lisa A Ostrin, Elise Harb, Debora L Nickla...

The choroid is the richly vascular layer of the eye located between the sclera and Bruch's membrane. Early studies in animals, as well as more recent studies in humans, have demonstrated that the choroid is a dynamic, multifunctional structure, with its thickness directly and indirectly subject to modulation by a variety of physiologic and visual stimuli. In this review, the anatomy and function of the choroid are summarized and links between the choroid, eye growth regulation, and myopia, as demonstrated in animal models, discussed. Methods for quantifying choroidal thickness in the human eye and associated challenges are described, the literature examining choroidal changes in response to various visual stimuli and refractive error-related differences are summarized, and the potential implications of the latter for myopia are considered. This review also allowed for the reexamination of the hypothesis that short-term changes in choroidal thickness induced by pharmacologic, optical, or environmental stimuli are predictive of future long-term changes in axial elongation, and the speculation that short-term choroidal thickening can be used as a biomarker of treatment efficacy for myopia control therapies, with the general conclusion that current evidence is not sufficient.

Topics: Animals; Humans; Axial Length, Eye; Choroid; Bruch Membrane; Myopia; Models, Animal; Tomography, Optical Coherence

PubMed: 37126359
DOI: 10.1167/iovs.64.6.4

Authors: Andrew P Voigt, Kelly Mulfaul, Nathaniel K Mullin...

The human retinal pigment epithelium (RPE) and choroid are complex tissues that provide crucial support to the retina. Disease affecting either of these supportive tissues can lead to irreversible blindness in the setting of age-related macular degeneration. In this study, single-cell RNA sequencing was performed on macular and peripheral regions of RPE-choroid from 7 human donor eyes in 2 independent experiments. In the first experiment, total RPE/choroid preparations were evaluated and expression profiles specific to RPE and major choroidal cell populations were identified. As choroidal endothelial cells represent a minority of the total RPE/choroidal cell population but are strongly implicated in age-related macular degeneration (AMD) pathogenesis, a second single-cell RNA-sequencing experiment was performed using endothelial cells enriched by magnetic separation. In this second study, we identified gene expression signatures along the choroidal vascular tree, classifying the transcriptome of human choriocapillaris, arterial, and venous endothelial cells. We found that the choriocapillaris highly and specifically expresses the regulator of cell cycle gene (), a gene that responds to complement activation and induces apoptosis in endothelial cells. In addition, was the most up-regulated choriocapillaris gene in a donor diagnosed with AMD. These results provide a characterization of the human RPE and choriocapillaris transcriptome, offering potential insight into the mechanisms of choriocapillaris response to complement injury and choroidal vascular disease in age-related macular degeneration.

Topics: Choroid; Epithelial Cells; Epithelium; Humans; Macular Degeneration; Retina; Single-Cell Analysis; Transcriptome

PubMed: 31712411
DOI: 10.1073/pnas.1914143116

Authors: Hao Wu, Guoyun Zhang, Meixiao Shen...

PURPOSE

To explore the association of choroidal vascularity and choriocapillaris blood perfusion with myopic severity in anisomyopes.

METHODS

Refractive error, axial length (AL), and other biometric parameters were measured in 34 anisomyopic young adults. Macular choroidal thickness (ChT) and choroidal vascularity, including total choroidal area (TCA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI), were determined from swept-source optical coherence tomography (SS-OCT) vertical and horizontal B-scans. The percentage of choriocapillaris flow voids (FV%) was obtained from en face SS-OCT-angiography.

RESULTS

The spherical equivalent refraction (SER) was -3.35 ± 1.25 diopters in the more myopic eyes and -1.25 ± 1.17 diopters in the less myopic eyes (P < 0.001). The interocular difference in SER was highly correlated with that in AL (P < 0.001). The macular ChT, TCA, LA, and SA were smaller in the more myopic eyes than in the less myopic eyes in both vertical and horizontal scans (all P < 0.001). Importantly, the CVIs in vertical and horizontal scans were smaller and the FV% was greater in the more myopic eyes (P < 0.05). In vertical scans, the interocular difference in CVIs was correlated with that in the SER, AL, and ChT (all P < 0.05). The interocular difference in FV% was correlated with that in SER, AL, and vertical and horizontal ChTs (all P < 0.05).

CONCLUSIONS

Choroidal vascularity and choriocapillaris blood perfusion were lower in the more myopic eyes of anisomyopic adults. These changes were correlated with the severity of myopia and choroidal thinning, indicating that choroidal blood flow is disturbed in human myopia.

Topics: Adult; Anisometropia; Biometry; Blood Physiological Phenomena; Choroid; Female; Fluorescein Angiography; Humans; Male; Myopia; Refraction, Ocular; Regional Blood Flow; Tomography, Optical Coherence; Young Adult

PubMed: 33393974
DOI: 10.1167/iovs.62.1.8

Review

Authors: Hideki Koizumi, Naoya Imanaga, Nobuhiro Terao...

Central serous chorioretinopathy (CSC) is a common disorder characterized by serous retinal detachment. Several studies using indocyanine green angiography (ICGA) have revealed that choroidal filling delay, choroidal vascular dilation, and choroidal vascular hyperpermeability are the characteristic findings of CSC. These ICGA findings confirm that choroidal circulatory disturbances are the primary factors in the pathogenesis of CSC. With advancements in optical coherence tomography (OCT), choroidal thickness has been found to be significantly greater in eyes with CSC than in normal eyes. Dilated large choroidal vessels reportedly account for the thickened choroid in eyes with CSC. Although many possible mechanisms and risk factors have been suggested, the pathophysiologic features of choroidal circulatory disturbances and choroidal thickening in eyes with CSC have not yet been fully elucidated. Recently, using anterior segment OCT, we proposed that the sclera may induce choroidal circulatory disturbances since CSC eyes have significantly thicker sclera than do normal eyes. This review summarizes updated information on the close relationship between CSC pathogenesis and the sclera.

Topics: Humans; Central Serous Chorioretinopathy; Tomography, Optical Coherence; Choroid; Fluorescein Angiography; Sclera; Fundus Oculi; Indocyanine Green

PubMed: 39150610
DOI: 10.1007/s10384-024-01101-2

Review

Authors: Elham Sadeghi, Nicola Valsecchi, Elham Rahmanipour...

Age-related macular degeneration (AMD) is the leading cause of central visual impairment in the elderly. The exact pathophysiological mechanisms for AMD remain uncertain. Several studies suggest that choroidal abnormalities and alterations are critical in AMD progression. The transition from manual to automated segmentation and binarization techniques has resulted in accurate and precise measurements of different choroidal parameters. These qualitative and quantitative parameters, known as choroidal imaging biomarkers, have advanced from basic vertical subfoveal choroidal thickness to more intricate 3-dimensional choroidal reconstruction methods in the last decade. Therefore, a comprehensive evaluation of choroidal metrics may investigate valuable insights into AMD, potentially guiding the future development of customized therapeutic strategies and personalized patient care in AMD management. We describe the role of different choroidal biomarkers in evaluating patients with AMD and their contribution to management.

Topics: Humans; Choroid; Biomarkers; Macular Degeneration; Tomography, Optical Coherence; Fluorescein Angiography

PubMed: 39426529
DOI: 10.1016/j.survophthal.2024.10.004

Authors: Raj S Hirawat, Arthi Mohankumar, C K Nagesha...

Topics: Choroid; Humans

PubMed: 35647952
DOI: 10.4103/ijo.IJO_2683_21

Authors: Santosh G Honavar

Topics: Child; Humans; Neurology; Ophthalmology; Uvea

PubMed: 29133626
DOI: 10.4103/ijo.IJO_1092_17