Ophthalmology Anatomy and Examination PDF

Anatomy of the eye and Ophthalmological examinations Lily Adhiambo Nyamai: MBChB, Mmed Ophthalmology (UoN), FCOECSA, PHERT, Fell Glaucoma (U of Toronto) Ophthalmologist, Glaucoma Specialist KU, Lecturer Department of Special Surgeries  ‘of all the senses the most p...

Anatomy of the eye and Ophthalmological examinations Lily Adhiambo Nyamai: MBChB, Mmed Ophthalmology (UoN), FCOECSA, PHERT, Fell Glaucoma (U of Toronto) Ophthalmologist, Glaucoma Specialist KU, Lecturer Department of Special Surgeries  ‘of all the senses the most pleasurable must be sight’ Helen Keller (author lecturer, political activist and lecturer) Objectives of today's lecture Learn to identify and examine the structures of the eye- anatomy (embryology and anatomy) Differentiate anatomy from ocular disorders External eye Globe (eyeball) Orbit- CT orbit ocular muscles and Orbit Retina and choroid Embryology External eye Conjunctiva Clear transparent Highly vascularized 3 geographic zones Bulbar conjunctiva Forneceal conjunctiva Palpebral conjunctiva Conjunctiva Conjunctival forms a fold as it moves along the eyelid Superior and inferior fornix (forniceal conjunctiva) Conjunctiva lining posterior eyelid; palpebral conjunctiva Conjunctiva ends at the mucocutaneous junction. Conjunctiva Bleeding beneath the conjunctiva is called a subconjunctival hemorrhage. Edema of conjunctiva is chemosis.  Eyelids 27-30mm Plica semilunaris Palpebral Caruncle fissure 8-11 mm Medial Canthus- Lateral angle rounder canthus-sharper angle Poll question Is this the right or left eye Orientation is key Eyelid The eyelid has Upper and lower lid Eyelid is divided into Anterior lamellae: skin, muscle and eyelashes (accessory lacrimal glands Zeiss and moll) Posterior lamellae: tarsus (within meibomian glands) and conjunctiva Stye -Infection of the gland of Zeiss is what is referred to as a stye. Eyelid Orbicularis oculi Innervation: CN VII Function: closing the lid What happens when one has bells palsy? Read more extensively on UMN and LMN lesions of CN VII Eyelid muscles LPS: elevates upper lid Function: innervated by CN III What happens to the eye lid in CN III palsy?  CN III PALSY The third cranial nerve also controls constriction of the pupil, the position of the upper eyelid, and the ability of the eye to focus. A complete third nerve palsy causes a completely closed eyelid and deviation of the eye outward and downward. Eyelid Upper and lower eyelid Anterior and posterior lamellae Posterior lamellae: tarsal plate (within its substance meibomian glands). Tarsal plate gives its eyelid shape. Conjunctiva Eyelid Chalazion The meibomian glands within the tarsal plate open up at the lid margin, posterior to the eyelashes. Blockage of these glands may lead to inflammation of the gland and swelling, which is referred to as a chalazion. Patient post repair of lid laceration what is the difference between right and left eyes? Repaired lid laceration with a notch and ptosis, HZO leisions Relevance The Lacrimal system Main lacrimal gland- reflex tearing Accessory lacrimal glands Meibomian glands- lipid layer Krause and Wolfring- aqueous layer Zeis and Moll-lipid layer Goblet- mucin layer Lacrimal drainage Pump: orbicularis occuli Tear film The tear film lines the cornea and conjunctiva, it nourishes, protects and is conduit for the removal of waste from these surfaces. Accessory lacrimal glands Meibomian glands- lipid layer Krause and Wolfring- aqueous layer Zeis and Moll-lipid layer Goblet- mucin layer Case: Lid laceration repaired involving the upper canaliculus Case: The lacrimal c/o: excessive tearing in her system left eye o/e: blockage of the common canauculus and nasolacrimal duct (NLD),swelling and skin discoloration over NLS area Imp: cannaliculitus and Dacryocystitis secondary to blockage of NLD Plan: insertion of a jones tube and ductocytorhinostomy (DCR))to drain the tears. The globe Sclera Sclera: white structure beneath the transparent conjunctiva 4/5 of globe Continuous with cornea but histologically different (irregular collagen fibres, hydrated) Posterior: passage ONH and continues as ON sheath EOM tendons insert into it  Clear structure and main refractive The globe- CORNEA structure of the eye +43D Clear structure and main refractive structure of the eye +43D The globe- cornea Measures: 10-11mm (H), 0.5mm thick centrally Collagen type 1 strands precisely organized and dehydrated Function depends on clarity and curvature.  Cornea cornea has 5 histological layers 1. Epithelium: impermeable, nonkeratinized, stratified squamous epithelial cells Stem cells: limbus (jxn sclera and cornea 5 layers- epithelium, Bowman, stroma, Descement and endothelium  Cornea 3. Stroma: largest substance. Collagen fibrils, uniform size and separation to maintain clarity. Dehydrated. 4.Descemet: BM of epithelium, collagen IV type. Mono-layer. Irreplaceable. Keeps cornea dehydrated (pump and active transport of ions). 2. Bowman layer (collagen)cannot be replenished and scars during perforations Slit lamp examination of cornea Cornea endothelial dysfunction Cornea ectasia Keratoconus  The chambers of the eye play the important role of maintaining the globes rigidity and structure. Chambers of the eye They are divided into the anterior chamber, posterior chamber and vitreous chambers. Vitreous chamber -largest chamber filled with vitreous humour Liquefaction of vitreous Posterior Vitreous detachment Posterior vitreous detachment Floaters Posterior chamber PC: Behind the iris, anterior to the ciliary body, zonules and the lens. Anterior chamber Boundaries Anterior: cornea Posterior: iris diaphragm, pupil Anterior chamber angle-junction between the iris and the pupil Anterior chamber Angle closure glaucoma Angle closure glaucoma vs none Slit beam Posterior cornea Iris surface Iris, ciliary body Iris what gives the eye its colour, continuous with CB controls size of the pupil Iris and ciliary body The ciliary body is a muscular structure that circles the eye along its length. Iris and ciliary body It is attached to the zonules and when it contracts the zonules slacken to make the lens more spherical and this is what allows you to focus on near objects. The lens Patient with a cataract and sublaxed lens Recap Eyelid Conjunctiva Lacrimal system and pre-corneal tear film Chambers of the eye Aqueous flow Globe- Cornea Sclera Iris and ciliary body Lens Retina The retina the structure that receives light and converts it into signals that can be transmitted to the brain for interpretation. Retina Orientation in the retina Instruments for viewing the retina Direct ophthalmoscope Slit lamp Instruments for viewing the retina- fundus camera Is there anything wrong with this retina? Retina vasculature Central retinal vein occlusion Macula Macula edema- anyone with diabetes needs a mandatory fundoscopy (retina exam yearly)  Optical Coherence Tomography (OCT)of the macula Normal OCT Macula edema on OCT Optic verve head(optic disc) Choriod Retina- retinal pigment epithelium The neurosensory retina How do you test for the function of the visual pathway? https://www.youtube.com/watch?v=Vp7LBSe7DcI Let’s use this moment to see examine pupillary testing https: //www.youtube.com/watch?v=wpG62cJMJcE Retinal detachment Retinal detachment Extraocular muscles Retrobulbar hemorrhage Nerve supply to the extraocular muscles Now let's look at this video on examination of extraocular movement https://www.youtube.com/watch?v=X0uM2NfO3Bk Quiz Orbit Orbit margins Orbit walls A little on the Embryology of the eye WEEK 1 n Morula stage Fertilisation Blastocyst implantation Week 2(Bilarminar disc stage) (week of twos) Week 3- Gastrulation-establishment of 3 germ layers(ectoderm, mesoderm and endoderm) and begins with formation of primitive streak Notochord formation-notochordal plate detaches from endoderm-17 Week 3 to 8 weeks- organogenesis of the eye occurs (day 22) Organogenesis of eye Day 22 optic sulci Optic pits evagination of sulci Pits deepen optic vessicles continous with neural tube, optic stalks Day 28-Focal thickening surface ecto lens placode Organogenesis nd of the eye- 2 month Cornea, iris Summary of the ophthalmological examination Visual acuity- home work https://www.youtube.com/watc h?v=0uDciOi6uYE&t=1s https://www.youtube.com/watc h?v=kMwy06mAV5U Summary Retina- Transducer. RPE-(outer layer optic cup) and neurosensory retina (inner Layer) Retina 2 vascilar supply inner 2/3 central retinal artery Outer 1/3 choroid. 7extraocular muscles – LR6 SO4 7 bones of the orbit. Summary The lavator muscles opens the eye and orbicularis closes it. Cornea dehydration maintains clarity Accommodation is the process that focuses objects at near Lacrimal glands consist of the main lacrimal gland and accessory lacrimal glands Lens has three layers. Thank you