• Basic Ophthalmology Pdf

Basic Ophthalmology is an ideal complement to the medical student curriculum and is a key text for primary care residents and physicians who want to broaden their knowledge of eye disease diagnosis and treatment. With this book, clinicians will learn how to obtain an appropriate ocular history and perform a complete eye evaluation. From the history and findings, the clinician should be able to diagnose and manage or refer common ocular disorders. This new edition includes content updates, 140+ figures and 17 video clips. The practical text summarizes important concepts, describes techniques step-by-step, and provides resources for additional information.Buku Ajar Fisiologi Kedokteran Ganong Pdf To Excel. Contents:. Introduction to Ophthalmology.

The Eye Examination. Acute Vision Loss. Chronic Vision Loss. The Red Eye. Ocular and Orbital Injuries. Amblyopia and Strabismus.

Neuro-Ophthalmology. Eyelid, Orbital, and Lacrimal Disease – new chapter. Drugs and the Eye 10th ed., 2016 Executive editor: Richard A. Harper, MD Print: 288 pages eBook: Access Basic Ophthalmology in a convenient, user-friendly digital format from your smartphone or tablet with the Academy eBooks app. Or read it online from your computer. Print ISBN: 978-1-61525-804-8 eBook ISBN: 978-1-61525-805-5 Customer Reviews.If you need to load by Richard A.

Harper pdf Basic Ophthalmology, in that case you come on to the faithful site. We have Basic Ophthalmology txt, ePub. Post navigation.

A view of the retina seen through an ophthalmoscope.In the center of the retina is the optic nerve, a circular to oval white area measuring about 2 x 1.5 mm across. From the center of the optic nerve radiate the major blood vessels of the retina. Approximately 17 degrees (4.5-5 mm), or two and half disc diameters to the left of the disc, can be seen the slightly oval-shaped, blood vessel-free reddish spot, the fovea, which is at the center of the area known as the macula by ophthalmologists. An animation of the view from iris to retina can be seen in. An animation from the iris to the retina.A circular field of approximately 6 mm around the fovea is considered the central retina while beyond this is peripheral retina stretching to the ora serrata, 21 mm from the center of the retina (fovea). The total retina is a circular disc of between 30 and 40 mm diameter.The retina is approximately 0.5 mm thick and lines the back of the eye.

The optic nerve contains the ganglion cell axons running to the brain and, additionally, incoming blood vessels that open into the retina to vascularize the retinal layers and neurons. A radial section of a portion of the retina reveals that the ganglion cells (the output neurons of the retina) lie innermost in the retina closest to the lens and front of the eye, and the photosensors (the rods and cones) lie outermost in the retina against the pigment epithelium and choroid. Light must, therefore, travel through the thickness of the retina before striking and activating the rods and cones. Subsequently the absorbtion of photons by the visual pigment of the photoreceptors is translated into first a biochemical message and then an electrical message that can stimulate all the succeeding neurons of the retina.

The retinal message concerning the photic input and some preliminary organization of the visual image into several forms of sensation are transmitted to the brain from the spiking discharge pattern of the ganglion cells. Light micrograph of a vertical section through central human retina.All vertebrate retinas are composed of three layers of nerve cell bodies and two layers of synapses. The outer nuclear layer contains cell bodies of the rods and cones, the inner nuclear layer contains cell bodies of the bipolar, horizontal and amacrine cells and the ganglion cell layer contains cell bodies of ganglion cells and displaced amacrine cells. Dividing these nerve cell layers are two neuropils where synaptic contacts occur. Light micrograph of a vertical section through the outer plexiform layer (OPL). Cone pedicles and rod spherules are the synaptic terminals of cones and rods. The outer nuclear layer (ONL) contains the cell bodies of rods and cones.

The innerThe second neuropil of the retina, is the inner plexiform layer (IPL), and it functions as a relay station for the vertical-information-carrying nerve cells, the bipolar cells, to connect to ganglion cells (Figs. In addition, different varieties of horizontally- and vertically-directed amacrine cells, interact in further networks to influence and integrate the ganglion cell signals. It is at the culmination of all this neural processing in the IPL that the message concerning the visual image is transmitted through ganglion cells to the brain along the optic nerve.

Foveal regions of primate retinas. Vertical section of the human fovea from Yamada, 1969 (11).

Os, outer segments; is, inner segments; OLM, outer limiting membrane; ONL, outer nuclear layer; H, Henle fibers; INL, inner nuclear layer; ILM,The foveal pit is an area where cone photoreceptors are concentrated at maximum density with exclusion of the rods, and arranged at their most efficient packing density which is in a hexagonal mosaic. This is more clearly seen in a tangential section through the foveal cone inner segments.

Tangential section through the human fovea. Reproduced from Ahnelt, Kolb and Pflug (1987) (13).Below this central 200 μm diameter central foveal pit, the other layers of the retina are displaced concentrically leaving only the thinnest sheet of retina consisting of the cone cells and some of their cell bodies.

Radially distorted but complete layering of the retina then appears gradually along the foveal slope (right and left sides of ) until the rim of the fovea is made up of the displaced second- and third-order neurons related to the central cones. Here the ganglion cells are piled into six layers so making this area, called the foveal rim or parafovea , the thickest portion of the entire retina. Ophthalmoscopic appearance of the retina to show the macula lutea (yellow area around the fovea).This pigmentation is the reflection from yellow screening pigments, the xanthophyll carotenoids zeaxanthin and lutein , present in the cone axons of the Henle fibre layer. The macula lutea is thought to act as a short wavelength filter, additional to that provided by the lens.

As the fovea is the most essential part of the retina for human vision, protective mechanisms for avoiding bright light and especially ultraviolet irradiation damage are essential. For if the delicate cones of our fovea are destroyed, we become blind.The yellow pigment that forms the macula lutea in the fovea can be clearly demonstrated by viewing a section of the fovea in the microscope with blue light. The dark pattern in the foveal pit extending out to the edge of the foveal slope is caused by the macular pigment distribution. Vertical section through the monkey fovea to show the distribution of the macula lutea (black). From Snodderly et al., 1984 (6).If one were to visualize the foveal photoreceptor mosaic as though the visual pigments in the individual cones were not bleached, one would see the picture shown in (lower frame) (picture from Lall and Cone, 1996).

The short-wavelength sensitive cones on the foveal slope look pale yellow green, the middle wavelength cones, pink and the long wavelength sensitive cones, purple. If we now add the effect of the yellow screening pigment of the macula lutea we see the appearance of the cone mosaic in (upper frame). The macula lutea helps enhance achromatic resolution of the foveal cones and blocks out harmful UV light irradiation ( from Abner Lall and Richard Cone, unpublished data). Blood supply to the retinaThere are two sources of blood supply to the mammalian retina: the central retinal artery and the choroidal blood vessels. The choroid receives the greatest blood flow (65-85%) and is vital for the maintainance of the outer retina (particularly the photoreceptors) and the remaining 20-30% flows to the retina through the central retinal artery from the optic nerve head to nourish the inner retinal layers.

The central retinal artery has 4 main branches in the human retina. Fundus photograph showing fluorescein imaging of the major arteries and veins in a normal human right eye retina. The vessels emerge from the optic nerve head and run in a radial fashion, curving toward and around the fovea (asterisk in photograph).The arterial intraretinal branches then supply three layers of capillary networks i.e. 1) the radial peripapillary capillaries (RPCs) and 2) an inner and 3) an outer layer of capillaries. The precapillary venules drain into venules and through the corresponding venous system to the central retinal vein.

Microvasculature of the retina. Flatmount view of a rat retina stained with NADPH-diaphorase at the level of focus of a major artery and arterioles.

Basic Ophthalmology Pdf

Flatmount view of a rat retina stained with NADPH-diaphorase at the level of focus ofThe radial peripapillary capillaries (RPCs) are the most superfical layer of capillaries lying in the inner part of the nerve fiber layer, and run along the paths of the major superotemporal and inferotemporal vessels 4-5 mm from the optic disk. The RPCs anastomose with each other and the deeper capillaries.

The inner capillaries lie in the ganglion cell layers under and parallel to the RPCs. The outer capillary network runs from the inner plexiform layer to the outer plexiform layer thought the inner nuclear layer.As will be noticed from the flourescein angiography of, there is a ring of blood vessels in the macular area around a blood vessel- and capillary-free zone 450-600 μm in diameter, surrounding the fovea. The macular vessels arise from branches of the superior temporal and inferotemporal arteries. At the border of the avascular zone the capillaries become two-layered and finally join as a single layered ring. The collecting venules are deeper (posterior) to the arterioles and drain blood flow back into the main veins. In the rhesus monkey this perimacular ring and blood vessel free fovea is clearly seen in the beautiful drawings made by Max Snodderly's group. Diagram of the retinal vasculature around the fovea in the rhesus monkey derived from more than 80 microscope fields.

The figure is from Snodderly et al., 1992 (9).The choroidal arteries arise from long and short posterior ciliary arteries and branches of Zinn's circle (around the optic disc). Each of the posterior ciliary arteries break up into fan-shaped lobules of capillaries that supply localized regions of the choroid. The macular area of the choroidal vessels is not specialized like the retinal blood supply is. The arteries pierce the sclera around the optic nerve and fan out to form the three vascular layers in the choroid: outer (most scleral), medial and inner (nearest Bruch’s membrane of the pigment epithelium) layers of blood vessels.

This is clearly shown in the corrosion cast of a cut face of the human choroid in. The corresponding venous lobules drain into the venules and veins that run anterior towards the equator of the eyeball to enter the vortex veins.

One or two vortex veins drain each of the 4 quadrants of the eyeball. The vortex veins penetrate the sclera and merge into the ophthalmic vein as shown in the corrosion cast of. Degenerative diseases of the human retinaThe human retina is a delicate organization of neurons, glia and nourishing blood vessels. In some eye diseases, the retina becomes damaged or compromised, and degenerative changes set in that eventually lead to serious damage to the nerve cells that carry the vital messages about the visual image to the brain.

We indicate four different conditions where the retina is diseased and blindness may be the end result.Age related macular degeneration is a common retinal problem of the aging eye and a leading cause of blindness in the world. The macular area and fovea become compromised due to the pigment epithelium behind the retina degenerating and forming drusen and allowing leakage of fluid behind the fovea. The cones of the fovea die causing central visual loss so we cannot read or see fine detail. A view of the fundus of the eye and of the retina in a patient who has age-related macular degeneration.Glaucoma is also a common problem in aging, where the pressure within the eye becomes elevated. The pressure rises because the anterior chamber of the eye cannot exchange fluid properly by the normal aqueous outflow methods. The pressure within the vitreous chamber rises and compromises the blood vessels of the optic nerve head and eventually the axons of the ganglion cells so that these vital cells die. Treatment to reduce the intraocular pressure is essential in glaucoma.

A view of the fundus of the eye and of the retina in a patient who has advanced glaucoma.Retinits pigmentosa is a nasty hereditary disease of the retina for which there is no cure at present. It comes in many forms and consists of large numbers of genetic mutations presently being analyzed. Most of the faulty genes that have been discovered concern the rod photoreceptors. The rods of the peripheral retina begin to degenerate in early stages of the disease. Patients become night blind gradually as more and more of the peripheral retina (where the rods reside) becomes damaged. Eventually patients are reduced to tunnel vision with only the fovea spared the disease process.

Characteristic pathology is the occurrence of black pigment in the peripheral retina and thinned blood vessels at the optic nerve head.