Ocular Aqueous Drainage Routes

The cribriform layer is composed of endothelial cells, fibroblasts, and collagen, and it is the major source of outflow resistance.

The canal of Schlemm is a large anular vessel that drains aqueous humor through internal collecting channels and external collecting channels into small veins, ultimately leading to the episcleral veins.

Acute glaucoma is characterized by obstruction at the periphery of the iris, leading to a rapid increase in intraocular pressure, whereas chronic glaucoma is characterized by gradual blockage of the trabecular meshwork, leading to a slow increase in intraocular pressure.

<p>In primary open-angle glaucoma, accumulation of collagen in the cribriform layer and within trabeculae leads to increased intraocular pressure.</p> Signup and view all the answers

<p>The aqueous veins are external collecting channels that bypass the limbal veins, carrying aqueous directly to the episcleral veins.</p> Signup and view all the answers

<p>The broad, flat cords in the corneoscleral portion, with fewer and smaller open spaces, influence aqueous drainage.</p> Signup and view all the answers

<p>To act as a filter, allowing fluids and large molecules to flow out and begin transformation to aqueous humour.</p> Signup and view all the answers

<p>Ultrafiltration</p> Signup and view all the answers

<p>It rises.</p> Signup and view all the answers

<p>15 mmHg, and it depends on the balance between aqueous production and drainage.</p> Signup and view all the answers

<p>They refine the filtration process, further filtering the resulting plasma to form aqueous humour.</p> Signup and view all the answers

<p>They have fenestrations on both inner and outer surfaces and are lined by a basement membrane, making them porous.</p> Signup and view all the answers

<p>10-15%</p> Signup and view all the answers

<p>Through the trabecular meshwork and the canal of Schlemm</p> Signup and view all the answers

<p>2-3 μl per minute</p> Signup and view all the answers

<p>The scleral spur</p> Signup and view all the answers

<p>Cords of collagen surrounded by endothelial cells</p> Signup and view all the answers

<p>The superficial episcleral vein</p> Signup and view all the answers

<p>The short distance between capillaries and the outside of the ciliary processes facilitates the production of aqueous humour by both epithelial layers.</p> Signup and view all the answers

<p>The contraction of the ciliary muscle pulls the ciliary body forward, relieving tension in the suspensory ligaments, making the elastic lens more convex, and increasing the refractive power of the lens.</p> Signup and view all the answers

<p>The parasympathetic nervous system stimulates the contraction of the ciliary muscle, while the sympathetic nervous system relaxes it.</p> Signup and view all the answers

<p>The periphery of the iris is attached to the anterior surface of the ciliary body, also known as the ciliary margin or root of the iris.</p> Signup and view all the answers

<p>Both epithelial layers, pigmented and non-pigmented, are involved in producing aqueous humour.</p> Signup and view all the answers

<p>Changes in ciliary muscle tension affect the outflow of aqueous humour in the eye.</p> Signup and view all the answers

<p>allow the stroma and deeper iris tissues to be bathed in aqueous humour and provide direct communication with the tissue spaces of the iris</p> Signup and view all the answers

<p>sphincter pupillae muscle and dilator pupillae muscle</p> Signup and view all the answers

<p>vascular connective tissue containing collagen fibers, fibroblasts, melanocytes, smooth muscles, and nerve fibers</p> Signup and view all the answers

<p>it is in contact with the aqueous humour and faces the posterior chamber, and the cells are packed with melanin</p> Signup and view all the answers

<p>they are caused by the folding of the iris as the pupil dilates</p> Signup and view all the answers

<p>they are apposed to each other apex to apex</p> Signup and view all the answers

<p>The ciliary epithelium produces aqueous humour through active transport of ions and water. Its structure of two layers of cubical cells covering the inner surface of the ciliary body enables it to secrete aqueous humour into the posterior chamber.</p> Signup and view all the answers

<p>Aqueous humour production occurs in the ciliary body, where the ciliary epithelium secretes ions and water into the posterior chamber through active transport. The ciliary stroma provides a vascular supply and structural support for the ciliary epithelium.</p> Signup and view all the answers

<p>The ciliary muscle changes the curvature of the lens during accommodation by contracting and relaxing, allowing the lens to focus on near or far objects. This is achieved through the ciliary muscle's contraction, which reduces the tension on the zonules, allowing the lens to become more convex.</p> Signup and view all the answers

<p>The iris is a ring-shaped structure that controls the amount of light entering the eye. The ciliary body is continuous anteriorly with the peripheral margin of the iris, and the pars plicata surrounds the iris.</p> Signup and view all the answers

<p>The ciliary muscle contraction reduces the tension on the suspensory ligaments (zonules), allowing the lens to become more convex and focus on near objects. The suspensory ligaments attach to the lens and the ciliary body, transmitting the force of the ciliary muscle contraction.</p> Signup and view all the answers

<p>The pars plicata is the anterior surface of the ciliary body, with ridges that increase the surface area for aqueous humour production. The pars plana is the posterior surface, which is smooth and flat. Both surfaces are involved in aqueous humour production, with the pars plicata being more active in this process.</p> Signup and view all the answers

<p>Fuch's crypts allow the aqueous humour to have a direct communication with the tissue spaces of the iris, bathing the stroma and deeper iris tissues in aqueous humour.</p> Signup and view all the answers

<p>The iris consists of two zones: the stroma and two epithelia layers. The stroma is composed of vascular connective tissue containing collagen fibres, fibroblasts, melanocytes, smooth muscles and nerve fibres. The two posterior epithelia layers consist of cells that are apposed to each other apex to apex.</p> Signup and view all the answers

<p>The sphincter pupillae muscle is a ring of smooth muscle fibres around the pupil that constricts the pupil when contracted. The dilator pupillae muscle is a thin layer of myoepithelium that dilates the pupil when contracted.</p> Signup and view all the answers

<p>The contraction furrows are caused by the folding of the iris as the pupil dilates.</p> Signup and view all the answers

<p>The two epithelial layers are apposed to each other apex to apex. The posterior epithelial layer is packed with melanin and faces the posterior chamber, being in contact with the aqueous humour.</p> Signup and view all the answers

<p>The stroma of the iris consists of vascular connective tissue containing collagen fibres, fibroblasts, melanocytes, smooth muscles and nerve fibres.</p> Signup and view all the answers

<p>The pupillary ruff is a ring of dark pigment that outlines the pupil, serving as a border between the pupil and the iris.</p> Signup and view all the answers

<p>The concentration of melanin in the iris determines eye color, with higher concentrations resulting in darker eye colors and lower concentrations resulting in lighter eye colors.</p> Signup and view all the answers

<p>The two main zones of the anterior surface of the iris are the central pupillary zone and the peripheral ciliary zone.</p> Signup and view all the answers

<p>Fuch's crypts are oval-shaped crypts in the iris that contain melanin, contributing to iris pigmentation and eye color.</p> Signup and view all the answers

<p>The ciliary ridge or collarette is a line of demarcation that separates the central pupillary zone from the peripheral ciliary zone on the anterior surface of the iris.</p> Signup and view all the answers

<p>The stroma of the iris contains melanocytes that produce melanin, which determines iris pigmentation and eye color.</p> Signup and view all the answers

<p>The main function of the ciliary body is to produce aqueous humor from blood, provide muscles that change the curvature of the lens, and maintain the lens zonules. The ciliary body is continuous posteriorly with the choroid and anteriorly with the peripheral margin of the iris.</p> Signup and view all the answers

<p>The pars plicata is the ridged or folded anterior surface of the ciliary body, which surrounds the iris and gives rise to the ciliary processes, increasing the surface area for aqueous humor production. The pars plana is the smooth and flat posterior surface.</p> Signup and view all the answers

<p>The ciliary epithelium is composed of two layers of cubical cells that cover the inner surface of the ciliary body, responsible for producing aqueous humor.</p> Signup and view all the answers

<p>The suspensory ligaments (zonules) of the lens are fibers made of fibrillin protein that attach to the surface of the pars plicata, playing a crucial role in maintaining the lens zonules.</p> Signup and view all the answers

<p>The contraction of the ciliary muscle changes the shape of the lens during accommodation, allowing the eye to focus on objects at different distances.</p> Signup and view all the answers

<p>The ciliary body is continuous posteriorly with the choroid and anteriorly with the peripheral margin of the iris.</p> Signup and view all the answers

<p>The OPL facilitates the transmission of signals from photoreceptors to bipolar cells, where the responses of photoreceptors are processed and transmitted to other neurons in the retina.</p> Signup and view all the answers

<p>ON-centre bipolars are depolarized (excited) by the release of glutamate, whereas OFF-centre bipolars are hyperpolarized (inhibited) by it.</p> Signup and view all the answers

<p>Receptive fields are critical in perimetry as they define the spatial extent of visual stimuli detection, influencing the processing of visual information in the visual pathway.</p> Signup and view all the answers

<p>Photoreceptors convert light into electrical signals, which are then transmitted to bipolar cells, initiating the visual signal processing pathway.</p> Signup and view all the answers

<p>Bipolar cells process visual information through graded potentials, which are proportional to the amount of glutamate released by photoreceptors, and transmit these signals to other neurons in the retina.</p> Signup and view all the answers

<p>The neural retina processes and transmits visual information from the photoreceptor layer to the brain, enabling visual perception.</p> Signup and view all the answers

<p>Horizontal cells synapse with bipolar cells indirectly and add an opponent signal to the receptive field, introducing centre-surround antagonism.</p> Signup and view all the answers

<p>ON-centre bipolar cells are excited by light, while OFF-centre bipolar cells are inhibited by light.</p> Signup and view all the answers

<p>Centre-surround organisation manifests as spatial antagonism, and the visual system responds strongly to luminance boundaries (local contrast) and less strongly to even, unchanging areas of luminance.</p> Signup and view all the answers

<p>ON-centre RGCs respond strongly to light on the centre of the receptive field and dark on the surround, while OFF-centre RGCs respond strongly to dark on the centre and light on the surround.</p> Signup and view all the answers

<p>The receptive field configuration, also known as the 'Mexican Hat' configuration, is crucial for the visual system's ability to detect contrast and edges.</p> Signup and view all the answers

<p>Amacrine cells are interneurons that carry information laterally through the inner plexiform layer and synapse with bipolar, amacrine, and ganglion cells. They help 'sharpen up' receptive fields of ganglion cells and play a role in modulating photoreceptor signals under different light levels, making them less sensitive in bright light and more sensitive in dim light.</p> Signup and view all the answers

<p>Amacrine cells modify the receptive fields of retinal ganglion cells, contributing to the centre-surround organisation.</p> Signup and view all the answers

<p>The dendritic field (DF) of a ganglion cell is the physical area of the dendritic arbour, whereas the receptive field (RF) of a ganglion cell describes the area of photoreceptors that will ultimately contribute to the response of the ganglion cells (after relay by bipolar cells).</p> Signup and view all the answers

<p>Each bipolar cell receives a direct input from a group of photoreceptors, which enables them to transmit visual signals. They also play a role in modulating photoreceptor signals under different light levels, making them less sensitive in bright light and more sensitive in dim light.</p> Signup and view all the answers

<p>Receptive fields are the areas of the visual field that produce a change in the response of a cell in the visual system. They play a crucial role in processing visual information, enabling the transmission of visual signals from the retina to the brain.</p> Signup and view all the answers

<p>Amacrine cells help 'sharpen up' receptive fields of ganglion cells, while horizontal cells modulate photoreceptor signals, making them less sensitive in bright light and more sensitive in dim light.</p> Signup and view all the answers

<p>The optic nerve transmits visual information from the retina to the brain, enabling the processing of visual information and perception.</p> Signup and view all the answers