Anatomy of eye

1–8 of 8 articles
  1. 2 Apr 2021 12 min read

    Anatomy of Conjunctiva

    Conjunctiva is a fine, translucent mucous membrane that joins and covers the anterior surface of eyeball and posterior side of the eyelids. It covers the posterior surface of the lids and reflects to cover the anterior part of the sclera, then becomes continuous with the corneal epithelium. At the lid margin conjunctiva is continuous with the skin. The name “conjunctiva” has originated from the term “conjoin” which means “to join” Parts of the conjunctiva: Broadly conjunctiva is divided into palpebral conjunctiva, fornices, and bulbar conjunctiva. Palpebral conjunctiva: It is the part of the conjunctiva that lines the undersurface or posterior surface of the eyelid. Latin word palpebrae mean “an eyelid” The palpebral conjunctiva is again subdivided into marginal conjunctiva, tarsal conjunctiva, and orbital conjunctiva. The marginal conjunctiva is a transitional zone between the skin of the eyelid and the conjunctiva proper. It starts from the intermarginal strips of the eyelid as a con

    Dr. Parthopratim Dutta Majumder
  2. 1 Apr 2021 28 min read

    Anatomy of Retina

    The retina is the innermost of the three coats of the eye. This layer is responsible for converting relevant information from the image of the external environment into neural impulses that are transmitted to the brain. Broadly retina consists of two primary layers: an inner neurosensory retina and retinal pigment epithelium (RPE). 1 ? Sensory retina develops from the inner layer of the neuroectoderm, whereas RPE is derived from the outer layer of the neuroectoderm. The RPE is continuous anteriorly with the pigment epithelium of the ciliary body. Sensory retina extends from the optic disc to ora serrata, where it is continuous with non-pigmented ciliary epithelium.1 Between the neural retina and RPE, there is a potential space known as subretinal space. The adhesion between neural retina and RPE is relatively weak. The neural retina is firmly attached at its anterior termination, the ora serrata, and at the margins of the optic nerve head. The ora serrata is located 4-6 mm behind cilia

    Dr. Parthopratim Dutta Majumder
  3. 1 Apr 2021 21 min read

    Anatomy of Uvea

    Uvea is the middle vascular coat of the eyeball. From anterior to posterior, the uvea or uveal tract can be divided into three parts- Iris, Ciliary body, and choroid. The name “uvea” has originated from the Latin word grape. Why a grape? If the stem is removed from a grape, the hole looks like the pupil and the grape the eyeball. Iris : Iris is the anterior-most part of the uveal tract. It is a thin and circular structure which forms a diaphragm like structure in front of the crystalline lens. The word “iris” has originated from a Greek word. In Greek mythology, the iris is the name of the Greek goddess of the rainbow. The diaphragm formed by the iris contains a central aperture known as the pupil. The location of the pupil is not exactly central, its little nasal to the center. The pupil determines the amount of light entering the eye. The normal size of the pupillary aperture is 3-4 mm. Details on the pupil will be discussed in chapter "Pupil". Iris is attached to the middle of the a

    Dr. Parthopratim Dutta Majumder
  4. 5 Apr 2020 7 min read

    Anatomy of Sclera

    The term sclera is derived from Greek word scleros meaning "hard".Sclera is an opaque, elastic, and resilient tissue of the eye. It can be compared with an incomplete shell comprising approximately 90% (five-sixths) of the outer coat of the eye. Anteriorly it begins at the limbus and terminates at the optic nerve canal posteriorly. The primary function of the sclera is to protect the eye and maintain the shape of the eye ball. Amazing Fact: Human beings are the only primates with white sclera Embryologically like corneal stroma and endothelium, sclera originates from mesoderm. The human sclera is white in colour. This white appearance is because of the scattering of all wavelengths of light by dense irregular bundles of collagen in sclera. In children, a bluish hue is observed because of the extremely thin sclera which allows the visibility of underlying choroid. In older age the sclera may appear slightly yellowish because of the deposition of fat. Thickness of sclera: Sclera is thick

    Dr. Parthopratim Dutta Majumder
  5. 5 Apr 2020 7 min read

    Anatomy of Anterior Chamber

    Anterior chamber is an angular space bounded anteriorly by the posterior (inner) surface of the cornea and posteriorly by the anterior surface of the iris and a part of cilliary body. Boundary of anterior chamber: Anteriorly Posteriorly Inner surface of the cornea At periphery, trabecular meshwork Lens, Anterior surface of the iris and Anterior face of the ciliary body Anterior chamber is 3 mm deep and it contains 0.25 ml of the aqueous humour. Anterior chamber depth is shallower in the hypermetropic eye than the myopic eye. It is also shallower in children and in older people. Anterior Chamber at a glance Volume: 220 µL. Chamber Volume decreases by 0.11 µL/year life Depth: 3.15mm (2.6- 4.4mm) Chamber depth decreases by 0.01mm/year of life. Chamber depth is shallower in the hypermetropic than myopic .Chamber deepens by 0.06mm for each diopter of myopia. Chamber depth is slightly diminished during accommodation, partly by increased lens curvature & partly by forward translocation of the

    Dr. Parthopratim Dutta Majumder
  6. 5 Apr 2020 4 min read

    Anatomy of Vitreous

    Vitreous is a transparent, colour less gel like structure which occupies the posterior compartment of the eye. It comprises about 80% of the total volume of the globe (two third of total volume of eye), about 4mL. The surfaces of the intraocular structures that interface with vitreous are mainly basement membrane in nature e.g. pars plana of cilliary body, internal limiting membrane of retina and vitreous is attached to them with varying strength of adhesion. Vitreous at a glance: Contains more than 98% of water It has viscosity more than 2-3 times than that of water. Refractive index 1.33 Ethymology: The word “vitreous” is derived from a Latin word “vitrum” which means glass. Attachments of vitreous: Vitreous is attached to its surrounding structures by condensation of collagen fibrils. From strongest to weakest, these are- Vitreous base-strongest Posterior lens capsule with the help of hyaloideocapsular ligament of Weiger Margins of the optic disc At the macula Along the retinal vess

    Dr. Parthopratim Dutta Majumder
  7. 5 Apr 2020 10 min read

    Anatomy of Lens

    The crystalline lens is a unique transparent, biconvex, avascular intraocular structure with slightly more curved posterior surface .The radius of curvature of anterior surface is 10 mm and that of posterior surface is 6 mm. Lens is a unique structure, which contains cells of a single type, in various stages of differentiation Topography: The center of the anterior surface is called anterior pole and it is situated 3mm away from the posterior (endothelial) surface of cornea. The center of the posterior surface is called posterior pole. The distance between these poles is measured as lens thickness. The thickness of lens is 3mm at birth, which increases to 6mm in older age. The marginal circumferences of the lens, where anterior and posterior surface meet, are known as equator. Equatorial or lens diameter is generally measured in nasal to temporal dimension. The equatorial diameter of lens is 6.5 mm at birth, which reaches to 9-10 mm in adult life. The equator of the lens is encircled b

    Dr. Parthopratim Dutta Majumder
  8. 5 Apr 2020 12 min read

    Anatomy of Cornea

    The cornea is the transparent tissue that covers the front of the eye.It forms anterior 1/6th of the outer fibrous coat of eyeball. The word cornea has come from “Kerato”. The term “Kerato” in greek means horn or shield like. Ancient Greek used to believe that cornea is derived from same material like that of thinly sliced horn of animal. Embryology: Structure Derived from Corneal epithelium Surface ectoderm Stroma, Descmet’s membrane, endothelium Paraxial mesoderm Topography: Anterior surface of the cornea is elliptical whereas posterior surface is spherical with average diameter 11.5 mm. Horizontal diameter of the anterior surface (HCD) is 11.7 mm and vertical diameter (VCD) is 11mm.Of them HCD is of clinically important.The radius of curvature of cornea is 8 (7.8 mm).It is the result of differences in radius of curvature in the vertical horizontal meridians which causes astigmatism. Microcornea = when HCD is less than 10mm Macrocornea = when HCD is more than 13 mm The central cornea

    Dr. Parthopratim Dutta Majumder