DOCSLIB.ORG

Anatomy of Eye Provided By

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Anatomy of Eye Provided By RIMT UNIVERSITY SCHOOL OF PHYSIOTHERAPY BACHELOR OF PHYSIOTHERAPY STUDY MATERIAL Topic: Anatomy Of Eye Provided By: Dr Ambuja Bhardwaj (PT) Subject: HUMAN ANATOMY II Subject code: BPT1201 Anatomy of Eye Introduction 1. The three coats of the eye are as follows: (a) Outer fibrous layer: The eye is the primary organ of vision. Each one • cornea of the two eyeballs is located in the orbit, where • sclera it takes up about one-fifth of the orbital volume • lamina cribrosa. (Figure 2.1). The remaining space is taken up (b) Middle vascular layer (“uveal tract”): by the extraocular muscles, fascia, fat, blood vessels, nerves and the lacrimal gland. •iris The eye is embryologically an extension of • ciliary body – consisting of the pars the central nervous system. It shares many plicata and pars plana common anatomical and physiological proper- • choroids. ties with the brain. Both are protected by bony (c) Inner nervous layer: walls, have firm fibrous coverings and a dual • pigment epithelium of the retina blood supply to the essential nervous layer in • retinal photoreceptors the retina. The eye and brain have internal cav- • retinal neurons. ities perfused by fluids of like composition and under equivalent pressures. As the retina and 2. The three compartments of the eye are as optic nerve are outgrowths from the brain, it is follows: not surprising that similar disease processes (a) Anterior chamber – the space between affect the eye and central nervous system. The the cornea and the iris diaphragm. physician should constantly remind himself or (b) Posterior chamber – the triangular space herself of the many disease conditions that can between the iris anteriorly, the lens and simultaneously involve the eye and the central zonule posteriorly, and the ciliary body. nervous system. (c) Vitreous chamber – the space behind the lens and zonule. 3. The three intraocular fluids are as follows: Basic Structure of the Eye and (a) Aqueous humour – a watery, optically Supporting Structures clear solution of water and electrolytes similar to tissue fluids except that The Globe aqueous humour has a low protein content normally. The eye has three layers or coats, three com- (b) Vitreous humour – a transparent gel partments and contains three fluids (Figure 2.2). consisting of a three-dimensional 7 8 Common Eye Diseases and their Management Upper palpebral furrow Mucocutaneous junction Cornea Iris Ciliary body Conjunctiva Upper punctum Sclera Caruncle Choroid Retina Lower punctum Openings of tarsal glands Figure 2.2. Layers of the globe. Semilunar folds Figure 2.1. Surface anatomy. sixths are formed by the sclera and lamina cribrosa. The cornea is transparent, whereas the sclera, which is continuous within it, is white. network of collagen fibres with the The junction of cornea and sclera is known as interspaces filled with polymerised the limbus. The cornea has five layers antero- hyaluronic acid molecules and water. It posteriorly (Figure 2.3): fills the space between the posterior surface of the lens, ciliary body and 1. Epithelium and its basement membrane – retina. stratified squamous type of epithelium (c) Blood – in addition to its usual func- with five to six cell layers of regular tions, blood contributes to the main- arrangement. tenance of intraocular pressure. Most 2. Bowman’s layer – homogeneous sheet of of the blood within the eye is in the modified stroma. choroid. The choroidal blood flow rep- 3. Stroma – consists of approximately 90% resents the largest blood flow per unit of total corneal thickness. Consists of tissue in the body. The degree of lamellae of collagen, cells and ground desaturation of efferent choroidal substance. blood is relatively small and indicates 4. Descemet’s membrane – the basement that the choroidal vasculature has membrane of the endothelium. functions beyond retinal nutrition. It 5. Endothelium – a single layer of cells lining might be that the choroid serves as a the inner surface of Descemet’s membrane. heat exchanger for the retina, which absorbs energy as light strikes the retinal pigment epithelium. Clinically, the eye can be considered to be Epithelium composed of two segments: Bowman’s membrane 1. Anterior segment – all structures from (and including) the lens forward. 2. Posterior segment – all structures post- Stroma erior to the lens. The Outer Layer of the Eye Descemet’s membrane Endothelium The anterior one-sixth of the fibrous layer of the eye is formed by the cornea. The posterior five- Figure 2.3. The cornea. Basic Anatomy and Physiology of the Eye 9 In the region of the limbus, the epithelium on of the triangle (mainly ciliary muscles) lies the outer surface of the cornea becomes con- against the sclera. The inner side is divided into tinuous with that of the conjunctiva, a thin, two zones: (1) the pars plicata forms the ant- loose transparent nonkeratinising mucous erior 2mm and is covered by ciliary processes membrane that covers the anterior part of the and (2) the pars plana constitutes the posterior sclera, from which it is separated by loose con- 4.5-mm flattened portion of the ciliary body. nective tissue.Above and below, the conjunctiva The pars plana is continuous with the choroid is reflected onto the inner surface of the upper and retina. and lower lids. This mucous membrane, there- The choroid consists of the following: fore, lines the posterior surface of the eyelids • Bruch’s membrane – membrane on the and there is a mucocutaneous junction on the external surface of the retinal pigment lid margin. Although the conjunctiva is con- epithelium (RPE). It consists of the base- tinuous,it can be divided descriptively into three ment membrane of RPE cells and chorio- parts: palpebral (tarsal), bulbar and fornix. capillaris. Between the two layers of The sclera consists of irregular lamellae of basement membrane are the elastic and collagen fibres. Posteriorly, the external two- collagenous layers. Small localised thick- thirds of the sclera become continuous with the enings of Bruch’s membrane (which dural sheath of the optic nerve, while the inner increase with age) are called drusen. one-third becomes the lamina cribrosa – the fenestrated layer of dense collagen fibres • The choriocapillaris – a network of capil- through which the nerve fibres pass from the laries supplying the RPE and outer retina. retina to the optic nerve. The sclera is thickest • Layer of larger choroidal blood vessels posteriorly and thinnest beneath the insertions external to the choriocapillaris. of the recti muscles. There is a layer of loose • Pigmented cells scattered in the choroid connective tissue deep to the conjunctiva, over- external to the choriocapillaris. lying the sclera, called the episclera. Inner Layer Middle Layer The inner layer of the eye, which lines the vas- The middle layer is highly vascular. If one were cular uvea, is the neurosensory layer. This layer to peel the sclera away from this layer (not an forms the retina posteriorly; but, anteriorly it easy task), the remaining structure would comes to line the inner surface of the ciliary resemble a grape, as this middle layer, which is body and iris as a two-layered pigment epithe- called the uvea, is heavily pigmented as well as lium. These same layers can be traced into the being vascular. The anterior part of the uvea retina, which is composed of an outer pigment forms the bulk of the iris body and hence epithelium and an inner sensory part, which inflammation of the iris is called either anterior contains the rods and cones, bipolar cells and uveitis or iritis. The posterior part of the uvea is ganglion cells (Figure 2.4). The junction of the called the choroid. retina and the pars plana forms a scalloped The iris is the most anterior part of the uvea. border known as the ora serrata. It is a thin circular disc perforated centrally It is important to note that the photoreceptor by the pupil. Contraction of the iris sphincter cells are on the external side of the sensory muscle constricts the pupil, while contraction of retina. The relationship of the retinal elements the dilator pupillae muscle dilates the pupil. can be understood most readily by following the The ciliary body is part of the uveal tissue and formation of the optic cup. As the single-cell is attached anteriorly to the iris and the scleral layer optic vesicle “invaginates”to form the two- spur; posteriorly it is continuous with the cell layered optic cup, the initially superficial choroid and retina. The ciliary body is also cells become the inner layer of the cup. The RPE referred to as the intermediate uvea. develops from the outer layer of the cup, facing The ciliary body is triangular in cross- the photoreceptors across the now obliterated section. The anterior side of the ciliary body is cavity of the optic vesicle. The neurons of the the shortest and borders the anterior chamber sensory retina differentiate from the inner layer angle; it gives origin to the iris. The outer side of the optic cup. 10 Common Eye Diseases and their Management Ganglion cells Bipolar cells Lacrimal gland Lacrimal artery Rods and cones Long posterior ciliary artery Optic nerve Pigment epithelium Ophthalmic artery Choroid Internal carotid artery Figure 2.4. The retina. Figure 2.5. Blood supply of the eye. Optic Nerve The optic nerve meets the posterior part of the Blood Supply globe slightly nasal to the posterior pole and slightly above the horizontal meridian. Inside The blood supply of the globe is derived from the eye this point is seen as the optic disc. There three sources: the central retinal artery, the are no light-sensitive cells on the optic disc – anterior ciliary arteries and the posterior ciliary and hence the blind spot that anyone can find in arteries.
Load more

Recommended publications
  • Openoptix NCLE Study Guide V0.2
    OpenOptix NCLE Study Guide Ver. 0.2 This document is licensed under the Creative Commons Attribution 3.0 License. 6/15/2009 1 About This Document The OpenOptix NCLE Study Guide, sponsored by Laramy-K Optical has been written and is maintained by volunteer members of the optical community. This document is completely free to use, share, and distribute. For the latest version please, visit www.openoptix.org or www.laramyk.com. The quality, value, and success of this document are dependent upon your participation. If you benefit from this document, we only ask that you consider doing one or both of the following: 1. Make an effort to share this document with others whom you believe may benefit from its content. 2. Make a knowledge contribution to improve the quality of this document. Examples of knowledge contributions include original (non-copyrighted) written chapters, sections, corrections, clarifications, images, photographs, diagrams, or simple suggestions. With your help, this document will only continue to improve over time. The OpenOptix NCLE Study Guide is a product of the OpenOptix initiative. Taking a cue from the MIT OpenCourseWare initiative and similar programs from other educational institutions, OpenOptix is an initiative to encourage, develop, and host free and open optical education to improve optical care worldwide. By providing free and open access to optical education the goals of the OpenOptix initiative are to: • Improve optical care worldwide by providing free and open access to optical training materials, particularly for parts of the world where training materials and trained professionals may be limited. • Provide opportunities for optical professionals of all skill levels to review and improve their knowledge, allowing them to better serve their customers and patients • Provide staff training material for managers and practitioners • Encourage ABO certification and advanced education for opticians in the U.S.
    [Show full text]
  • Shape of the Posterior Vitreous Chamber in Human Emmetropia and Myopia
    City Research Online City, University of London Institutional Repository Citation: Gilmartin, B., Nagra, M. and Logan, N. S. (2013). Shape of the posterior vitreous chamber in human emmetropia and myopia. Investigative Ophthalmology and Visual Science, 54(12), pp. 7240-7251. doi: 10.1167/iovs.13-12920 This is the published version of the paper. This version of the publication may differ from the final published version. Permanent repository link: https://openaccess.city.ac.uk/id/eprint/14183/ Link to published version: http://dx.doi.org/10.1167/iovs.13-12920 Copyright: City Research Online aims to make research outputs of City, University of London available to a wider audience. Copyright and Moral Rights remain with the author(s) and/or copyright holders. URLs from City Research Online may be freely distributed and linked to. Reuse: Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. City Research Online: http://openaccess.city.ac.uk/ [email protected] Visual Psychophysics and Physiological Optics Shape of the Posterior Vitreous Chamber in Human Emmetropia and Myopia Bernard Gilmartin, Manbir Nagra, and Nicola S. Logan School of Life and Health Sciences, Aston University, Birmingham, United Kingdom Correspondence: Bernard Gilmartin, PURPOSE. To compare posterior vitreous chamber shape in myopia to that in emmetropia. School of Life and Health Sciences, Aston University, Birmingham, UK, METHODS.
    [Show full text]
  • Foveola Nonpeeling Internal Limiting Membrane Surgery to Prevent Inner Retinal Damages in Early Stage 2 Idiopathic Macula Hole
    Graefes Arch Clin Exp Ophthalmol DOI 10.1007/s00417-014-2613-7 RETINAL DISORDERS Foveola nonpeeling internal limiting membrane surgery to prevent inner retinal damages in early stage 2 idiopathic macula hole Tzyy-Chang Ho & Chung-May Yang & Jen-Shang Huang & Chang-Hao Yang & Muh-Shy Chen Received: 29 October 2013 /Revised: 26 February 2014 /Accepted: 5 March 2014 # Springer-Verlag Berlin Heidelberg 2014 Abstract Keywords Fovea . Foveola . Internal limiting membrane . Purpose The purpose of this study was to investigate and macular hole . Müller cell . Vitrectomy present the results of a new vitrectomy technique to preserve the foveolar internal limiting membrane (ILM) during ILM peeling in early stage 2 macular holes (MH). Introduction Methods The medical records of 28 consecutive patients (28 eyes) with early stage 2 MH were retrospectively reviewed It is generally agreed that internal limiting membrane (ILM) and randomly divided into two groups by the extent of ILM peeling is important in achieving closure of macular holes peeing. Group 1: foveolar ILM nonpeeling group (14 eyes), (MH) [1]. An autopsy study of a patient who had undergone and group 2: total peeling of foveal ILM group (14 eyes). A successful MH closure showed an area of absent ILM sur- donut-shaped ILM was peeled off, leaving a 400-μm-diameter rounding the sealed MH [2]. ILM over foveola in group 1. The present ILM peeling surgery of idiopathic MH in- Results Smooth and symmetric umbo foveolar contour was cludes total removal of foveolar ILM. However, removal of restored without inner retinal dimpling in all eyes in group 1, all the ILM over the foveola causes anatomical changes of the but not in group 2.
    [Show full text]
  • Ophthalmology Ophthalmology 160.01
    Introduction to Ophthalmology Ophthalmology 160.01 Fall 2019 Tuesdays 12:10-1 pm Location: Library, Room CL220&223 University of California, San Francisco WELCOME OBJECTIVES This is a 1-unit elective designed to provide 1st and 2nd year medical students with - General understanding of eye anatomy - Knowledge of the basic components of the eye exam - Recognition of various pathological processes that impact vision - Appreciation of the clinical and surgical duties of an ophthalmologist INFORMATION This elective is composed of 11 lunchtime didactic sessions. There is no required reading, but in this packet you will find some background information on topics covered in the lectures. You also have access to Vaughan & Asbury's General Ophthalmology online through the UCSF library. AGENDA 9/10 Introduction to Ophthalmology Neeti Parikh, MD CL220&223 9/17 Oculoplastics Robert Kersten, MD CL220&223 9/24 Ocular Effects of Systemic Processes Gerami Seitzman, MD CL220&223 10/01 Refractive Surgery Stephen McLeod, MD CL220&223 10/08 Comprehensive Ophthalmology Saras Ramanathan, MD CL220&223 10/15 BREAK- AAO 10/22 The Role of the Microbiome in Eye Disease Bryan Winn, MD CL220&223 10/29 Retinal imaging in patients with hereditary retinal degenerations Jacque Duncan, MD CL220&223 11/05 Pediatric Ophthalmology Maanasa Indaram, MD CL220&223 11/12 Understanding Glaucoma from a Retina Circuit Perspective Yvonne Ou, MD CL220&223 11/19 11/26 Break - Thanksgiving 12/03 Retina/Innovation/Research Daniel Schwartz, MD CL220&223 CONTACT Course Director Course Coordinator Dr. Neeti Parikh Shelle Libberton [email protected] [email protected] ATTENDANCE Two absences are permitted.
    [Show full text]
  • Clinical Study Photoreceptor Inner and Outer Segment Junction Reflectivity After Vitrectomy for Macula-Off Rhegmatogenous Retinal Detachment
    Hindawi Publishing Corporation Journal of Ophthalmology Volume 2015, Article ID 451408, 7 pages http://dx.doi.org/10.1155/2015/451408 Clinical Study Photoreceptor Inner and Outer Segment Junction Reflectivity after Vitrectomy for Macula-Off Rhegmatogenous Retinal Detachment Jakub J. Kaluzny,1,2 Bartosz L. Sikorski,3 Grzegorz Czajkowski,2 Mateusz Burduk,3 Bartlomiej J. Kaluzny,3 Joanna Stafiej,3 and Grazyna Malukiewicz3 1 Department of Public Health, Collegium Medicum, Nicolaus Copernicus University, Ulica Sandomierska 16, 85-830 Bydgoszcz, Poland 2Oftalmika Eye Hospital, Ulica Modrzewiowa 15, 85-631 Bydgoszcz, Poland 3Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Ulica Marii Curie-Skłodowskiej 9, 85-094 Bydgoszcz, Poland Correspondence should be addressed to Jakub J. Kaluzny; [email protected] and Bartosz L. Sikorski; [email protected] Received 4 May 2015; Revised 26 June 2015; Accepted 1 July 2015 AcademicEditor:LawrenceS.Morse Copyright © 2015 Jakub J. Kaluzny et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Purpose. To evaluate the spatial distribution of photoreceptor inner and outer segment junction (IS/OS) reflectivity changes after successful vitrectomy for macula-off retinal detachment (PPV-mOFF) using spectral domain optical coherence tomography (SdOCT). Methods. Twenty eyes after successful PPV-mOFF were included in the study. During a mean follow-up period of 15.3 months, SdOCT was performed four times. To evaluate the IS/OS reflectivity a four-grade scale was used. Results. At the first follow- up visit the IS/OS had very similar reflectivity in entire length of the central scan with total average value of 1,05.
    [Show full text]
  • Pars Plana Vitrectomy for Symptomatic Vitreous Floaters
    ISSN: 2378-346X Waseem et al. Int J Ophthalmol Clin Res 2021, 8:124 DOI: 10.23937/2378-346X/1410124 Volume 8 | Issue 1 International Journal of Open Access Ophthalmology and Clinical Research ORIGINAL RESEARCH Pars Plana Vitrectomy for Symptomatic Vitreous Floaters: Another Look Tayab C Waseem, PhD, Evan R DaBreo, MD, Jiang Douglas, MS, Yousef Hasanzadah, BS, Rebecca Clawson, BS, Alan L Wagner, MD, FACS and Kapil G Kapoor, MD, FACS* Check for updates Wagner Macula & Retina Center, Eastern Virginia Medical School, USA *Corresponding author: Kapil G. Kapoor, MD, FACS, Wagner Macula & Retina Center, 5520 Greenwich Road Suite 204, Virginia Beach, VA 23462, USA, Tel: 757-481-4400, Fax: 757-481-1285 plaint which until recently was not often considered for Abstract surgical intervention [1-3]. Primary vitreous floaters are Introduction: Historically, pars plana vitrectomy (PPV) has the results of aggregated endogenous collagen fibrils of been considered a controversial treatment for elective re- moval of primary symptomatic vitreous opacities (floaters) the vitreous body which disrupt and scatter light on its due to the possibility of extreme and even blinding side ef- path to the retina. Vitreous floaters can be progressive fects of the procedure. The purpose of this study is to deter- in young patients with axial myopia and older patients mine the safety and patient satisfaction level for those who due to aging as the vitreous body liquefies and bundled undergo PPV for removal of vitreous floaters. collagen fibrils become thickened and more numerous Methods: This was a retrospective study of 54 eyes in 51 [3,4]. Primary vitreous floaters of sudden onset can be patients (average age 68) who underwent 23 gauges PPV the result of posterior vitreous detachment often re- between 2014 and 2017.
    [Show full text]
  • Introduction Goals Angle Anatomy Overview
    6/12/2019 Anterior Chamber Angle: Introduction Assessment and Anomalies Native Oregonian and Willamette Bearcat UC Berkeley School of Optometry 2008 San Francisco VA Residency 2009 VA Staff Optometrist – teaching Dave Hicks, OD, FAAO Regular lecturer at AAO and other meetings GWCO No conflicts of interest Portland, OR October 10, 2019 Goals Review anatomy of the anterior chamber angle Review gonioscopy and other imaging techniques for evaluating the angle and anterior chamber Discuss abnormal angle and anterior chamber findings and management www.gettyimages.com Angle Anatomy Overview Iris Ciliary body (CB) Scleral spur (SS) Trabecular meshwork (TM) Pigmented and non-pigmented Schwalbe’s Line (SL) Sampaolesi’s line when pigmented www.oculist.net 1 6/12/2019 Angle Anatomy Overview SL Iris processes TM Fine extensions toward TM or SL Usually still allow a view of the angle SS Differentiate from peripheral ant. synechiae (PAS) CB Greater circle of iris (MAC) Anterior ciliary and long posterior ciliary arteries Iris Both normal, but could mimic NV http://projects.mtmercy.edu/library/Tillage2/allen15.jpg Iris Processes Usually end at SS, but can go to SL Ferreras. Glaucoma Imaging, 2012. Stamper, Lieberman, Drake. Diagnosis and Therapy of the Glaucomas, 2009. www.oculist.net from Wolff E: Anatomy of the Eye and Orbit, 4th ed. Blakiston-McGraw, 1954. Angle Vessels Angle Neovascularization (NVA) Differentiate from normal iris vessels Causes – DM, CRVO, OIS, tumor, etc. Significance Evaluation – gonio Management – depends on etiology http://dro.hs.columbia.edu/circvessels.htm http://glaucomaassociates.com/glaucoma/types-of-glaucoma/#Neovascular Glaucoma 2 6/12/2019 Angle Function Van Herick Estimation (1969) Maintain IOP Angle Limbal AC Depth Grade vs.
    [Show full text]
  • Ciliary Body
    Ciliary body S.Karmakar HOD Introduction • Ciliary body is the middle part of the uveal tract . It is a ring (slightly eccentric ) shaped structure which projects posteriorly from the scleral spur, with a meridional width varying from 5.5 to 6.5 mm. • It is brown in colour due to melanin pigment. Anteriorly it is confluent with the periphery of the iris (iris root) and anterior part of the ciliary body bounds a part of the anterior chamber angle. Introduction • Posteriorly ciliary body has a crenated or scalloped periphery, known as ora serrata, where it is continuous with the choroid and retina. The ora serrata exhibits forward extensions,known as dentate process, which are well defined on the nasal side and less so temporally. • Ciliary body has a width of approximately 5.9 mm on the nasal side and 6.7 mm on the temporal side. Extension of the ciliary body On the outside of the eyeball, the ciliary body extends from a point about 1.5 mm posterior to the corneal limbus to a point 6.5 to 7.5 mm posterior to this point on the temporal side and 6.5 mm posterior on the nasal side. Parts of ciliary body • Ciliary body, in cross section, is a triangular structure ( in diagram it can be compared as ∆ AOI). Outer side of the triangle (O) is attached with the sclera with suprachoroidal space in between. Anterior side of the triangle (A) forms part of the anterior & posterior chamber. In its middle, the iris is attached. The inner side of the triangle (I) is divided into two parts.
    [Show full text]
  • Pars Plana Vitrectomy with the “Reinverting Operating Lens System”: a Step-Up in Vitreo Retinal Surgery
    Pars plana vitrectomy with the “reinverting operating le n s system”: a step-up in vitreo retinal surgery Vitrectomia via pars plana com “sistema de lentes de inversão operatória ”: um passo a frente em cirurgia vitreo-retiniana Osias Francisco de Souza1 ABSTRACT Newton Kara-José2 Objective: To analyze the efficacy of the panoramic viewing system (PVS) Reinverting Operating Lens System (ROLS) and the plano-concave Landers lens system in pars plana vitectomy (PPV). Methods: The authors retros- pectively analyzed the records of 117 PPV, 87 patients, performed between December 1996 and August 1998. The PPV was divided into two groups. Group 1 included 54 surgeries, with the Landers system. Group 2 included 63 surgeries with the ROLS. Results: There were no statistical significant differences between the two groups, regarding pre and postoperative parameters. Surgeries employing the Landers system had an average time significantly higher than the ROLS group (p<0.001). When the surgical time was analyzed according to the disease, surgeries lasted significantly longer when the Landers system was used (p<0.05), except for the Uveitis group (p= 0.262). Surgeries in group 2 required less air-fluid and lens exchanges, less use of perfluorocarbon liquid (PFCL), and less need for scleral depression during the procedure. Conclusion: The use of ROLS significantly reduced the time for PPV, lowering the need for air-fluid exchange, lens exchange, PFCL use, and scleral depression. The PVS ROLS offered several advantages over the Landers plano-concave lens system during the surgery, without changing the final results. Keywords: Vitrectomy/methods; Ophthalmologic surgical procedures/methods; Retinal diseases /surgery INTRODUCTION Since three-port pars plana vitrectomy (PPV) was first performed in a human in 1970(1), vitrectomy techniques have improved continuously in order to be more efficient.
    [Show full text]
  • Participation of Retinal Glucagonergic Amacrine Cells in the Regulation of Eye Growth and Refractive Error: Evidence from Neurotoxins and in Vivo Immunolesioning
    Participation of retinal glucagonergic amacrine cells in the regulation of eye growth and refractive error: evidence from neurotoxins and in vivo immunolesioning by Diane Rachel Nava A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Vision Science in the Graduate Division Of the University of California, Berkeley Committee in charge: Professor Christine F. Wildsoet, Chair Professor John Flanagan Professor Joseph Napoli Spring 2016 Participation of retinal glucagonergic amacrine cells in the regulation of eye growth and refractive error: evidence from neurotoxins and in vivo immunolesioning C 2016 By Diane Rachel Nava University of California, Berkeley Abstract Participation of retinal glucagonergic amacrine cells in the regulation of eye growth and refractive error: evidence from neurotoxins and in vivo immunolesioning by Diane Rachel Nava Doctor of Philosophy in Vision Science University of California, Berkeley Professor Christine Wildsoet, Chair Growth is one of the fundamental characteristics of biological systems. The study of eye growth regulation presents an interesting window that allows for the investigation of the role of the visual environment on internal processes. We now know that there is an intricate circuitry within the eye, independent of higher brain processes, that controls the growth of the eye but more needs to be elucidated about these local regulatory circuits. An improved understanding of this circuitry is critical to developing new therapies for abnormalities in eye growth regulation such as myopia, which is impacting more and more individuals around the world each day and in its more severe from, is linked to potentially blinding ocular complications.
    [Show full text]
  • Pars Plana Vitreous Tap for Phacoemulsification in the Crowded Eye
    techniques Pars plana vitreous tap for phacoemulsification in the crowded eye David F. Chang, MD ABSTRACT This technique facilitates phacoemulsification and foldable intraocular lens (IOL) im- plantation in eyes with extremely crowded anterior segments. An automated pars plana vitreous tap is used to expand the anterior segment when extremely shallow anterior chambers do not deepen sufficiently with viscoelastic injection alone. This technique permits successful completion of pupilloplasty, capsulorhexis, phacoemulsification, and foldable IOL implantation in these high-risk eyes. J Cataract Refract Surg 2001; 27:1911–1914 © 2001 ASCRS and ESCRS he crowded anterior segment presents one of the scribe the use of an automated pars plana vitreous tap to Tmost challenging situations for the phacoemulsifi- facilitate small incision cataract surgery. cation surgeon. Whether because of a short axial length, a larger lens, or a combination, these eyes present with Surgical Technique narrow angles and shallow anterior chambers. As a re- sult, they carry an increased risk of peripheral capsulo- If a vitreous tap is anticipated, a retrobulbar local rhexis tears, corneal decompensation, and intraoperative anesthetic agent is administered. An attempt is made to suprachoroidal hemorrhage.1 Although injection of a deepen the anterior chamber by injecting a retentive, viscoelastic substance usually provides enough room to dispersive viscoelastic substance through a clear corneal perform phacoemulsification, we occasionally encoun- stab incision. This is stopped once the globe starts to ter eyes with anterior chambers so shallow that they do become firm to prevent iris prolapse. In cases in which not deepen sufficiently with viscoelastic material. I de- the anterior chamber remains virtually flat, a pars plana vitreous tap is performed in the following manner: A small conjunctival incision is created at the intended site.
    [Show full text]
  • A Pilot Study of Pars Plana Vitrectomy, Intraocular Gas, and Radial Neurotomy in Ischaemic Central Retinal Vein Occlusion
    1126 Br J Ophthalmol: first published as 10.1136/bjo.87.9.1126 on 20 August 2003. Downloaded from EXTENDED REPORT A pilot study of pars plana vitrectomy, intraocular gas, and radial neurotomy in ischaemic central retinal vein occlusion T H Williamson, W Poon, L Whitefield, N Strothoudis, P Jaycock ............................................................................................................................. Br J Ophthalmol 2003;87:1126–1129 Background/aims: There is no effective treatment for ischaemic central retinal vein occlusion (CRVO). The two major negative outcomes are neovascular glaucoma (NVG) and severe central visual loss. In this study pars plana vitrectomy (PPV), mild panretinal photocoagulation, and intraocular gas injection were employed to prevent NVG. The potential role of incision of the lamina cribrosa (radial neurotomy) for visual recovery was examined. See end of article for Methods: Eight eyes of seven patients with ischaemic CRVO had PPV, mild panretinal photocoagula- authors’ affiliations tion, and intraocular perfluoropropane gas injection. Four eyes had radial neurotomies performed. The ....................... patients were examined by fundus photography, fundus fluorescein angiography, optical coherence Correspondence to: tomography, and Goldmann visual field analysis. Tom H Williamson, Results: No patients suffered from neovascular glaucoma. Visual recovery was seen in patients with Department of and without neurotomy but some patients had cataract extraction to allow visualisation for PPV. Fundus Ophthalmology, St photography demonstrated reduced engorgement of retinal veins in two of the patients with neurotomy Thomas’s Hospital, Lambeth Palace Road, and one with PPV alone. Optical coherence tomography demonstrated macular oedema in three London SE1 7EH, UK; patients with neurotomy and all patients with PPV alone. Segmental visual field loss was seen in one [email protected] patient with neurotomy suggesting damage to the optic nerve head.
    [Show full text]