Ophthalmic Surgery Lecture Notes

OPHTHALMIC SURGERY
25 LEARNING OBJECTIVES

  • Identify key anatomical structures of the eye

  • Discuss common diagnostic procedures of the eye

  • Discuss specific elements of case planning for eye surgery

  • Discuss surgical techniques used in eye surgery, including the use of the operating microscope

  • Describe common surgical procedures of the eye

*622 Eye Muscles Superior Inferior - Oblique

Lacrimal Apparatus - drains aqueous humor may need a stent to help keep it open. DCR - 636 - Tear duct gets blocked, Eye boogers.

TERMINOLOGY

  • Accommodation: A process in which the lens continually changes shape to maintain the focus of an image on the retina.

  • Cataract: Clouding of vision caused by a disease in which the crystalline lens of the eye, its capsule, or both become opaque, preventing light from focusing on the retina, resulting in visual distortion.

  • Cryotherapy: A technique in which a cold probe is used to freeze tissue, including the sclera, ciliary body (for glaucoma), or retinal layers after detachment.

  • Diathermy: Low-power cautery used to burn the sclera over an area of retinal detachment.

  • Enucleation: Surgical removal of the globe and accessory attachments.

  • Evisceration: Surgical removal of the contents of the eyeball with the sclera left intact.

  • Exenteration: Removal of the entire contents of the orbit.

  • Focal point: The point where light rays converge after passing through a lens.

  • Glaucoma: A group of diseases characterized by elevation of the intraocular pressure (IOP), which may result in ischemia and blindness.

  • Keratoplasty: Surgery of the cornea, with penetrating keratoplasty referring to a corneal transplantation.

  • Muscle recession: Surgery in which the eye muscle is moved back to release the globe.

  • Muscle resection: Surgical shortening of an eye muscle to pull the globe into correct position.

  • Phacoemulsification: A process where high-frequency sound waves are used to emulsify tissue, such as a cataract.

  • Pterygium: A triangular membrane arising from the medial canthus; tissue may extend over the cornea, causing blindness.

  • Refraction: A phenomenon where light rays are bent as they pass through a transparent medium denser than air, occurring in the eye as light enters through the cornea, lens, aqueous humor, and vitreous.

  • Spatula needle: A flat-tipped suture needle commonly used in ophthalmic surgery.

  • Strabismus: Inability to coordinate the extraocular muscles, preventing binocular vision.

OVERVIEW OF OPHTHALMIC SURGERY

  • The goal of ophthalmic surgery is to restore vision lost due to disease, injury, or congenital defect. Procedures target both external and internal structures of the eye and require teamwork and attention to detail due to their precision.

  • Ophthalmic procedures take place in various healthcare settings, including hospitals and outpatient centers, where patient safety measures in the perioperative period include verifying operative site and implant correctness, positioning precautions, and ensuring drug and patient environmental safety.

SURGICAL ANATOMY

ORBITAL CAVITY

  • The globe is housed within the orbital cavity (bony orbit), formed by seven bones: frontal, lacrimal, sphenoid, ethmoid, maxillary, zygomatic, and palatine bones.

  • The orbital rim, composed of thick bone, provides additional protection. The optic nerve enters through the optic foramen.

EYELIDS

  • Composed of fibrous connective tissue (tarsal plate) covered by skin, eyelids protect the eye from injury and light.

  • The interval between the upper and lower eyelids is the palpebral fissure, and the junctures are the canthi.

  • Sebaceous glands along the lid margin secrete oil, and eyelashes help filter airborne particles.

GLOBE

  • The eye's interior comprises multiple cavities, primarily the posterior cavity filled with vitreous gel and the anterior cavity divided into the anterior and posterior chambers.

  • Each eye and muscle is connected by six muscles, allowing movement around various axes for binocular vision.

CONJUNCTIVA

  • A thin, transparent mucous membrane lining the eyelids (palpebral conjunctiva) reflects onto the globe (bulbar conjunctiva), where it appears white due to the underlying sclera.

CORNEA - What is donated in eye transplants - keratoplasty corneal transplantation

  • A clear tissue layer at the eye’s front, the cornea refracts light, is avascular, and has three distinct layers: epithelium, stroma, and endothelium. The initial incision during cataract surgery is made at the limbus.

SCLERA

  • A thick, white fibrous tissue encasing three-fourths of the eyeball, the sclera connects with the cornea.

CHOROID LAYER AND CILIARY BODY

  • The choroid layer, rich in blood vessels, lies beneath the sclera and prevents light reflection.

  • The ciliary body, an extension of the choroid, consists of smooth muscle tissue responsible for lens shape adjustment.

IRIS

  • A muscle tissue layer around the pupil, the iris manages light to the inner eye, causing pupil dilation or constriction based on muscle activity.

RETINA

  • The innermost layer that receives light and forms nerve impulses, transmitting images to the brain via the optic nerve. Contains photoreceptor cells for black, white, and color vision, centered at the macula and fovea centralis.

LENS

  • A biconvex disc behind the iris, held by suspensory ligaments that adjust its shape to focus images on the retina.

ANTERIOR AND POSTERIOR CHAMBERS

  • The anterior cavity is divided into anterior and posterior chambers, the only communication between them occurring through the pupil.

  • Aqueous humor fills these chambers, produced by the ciliary epithelium and drained through the canal of Schlemm.

LACRIMAL APPARATUS

  • The lacrimal apparatus includes the lacrimal gland, caruncle, tear ducts, and nasolacrimal duct, which collectively produce and drain tears.

REFRACTION

  • Refraction is the bending of light rays when entering the eye's front, focusing images on the retina through accommodation, where the lens shape adjusts to keep images clear across distances.

DIAGNOSTIC TESTING

  • Refraction Test: Measures visual acuity with a phoropter and eye chart.

  • Slit Lamp: Examines the anterior chamber.

  • Tonometer: Measures intraocular pressure (IOP).

  • Ophthalmoscope: Directly examines internal eye structures.

  • Fluorescein Angiography: Diagnoses retinal and choroidal diseases.

  • Ophthalmic Ultrasonography: Detects abnormalities based on tissue density.

  • Imaging Tests: MRI and CT evaluate orbital and intracranial structures.

CASE PLANNING

PSYCHOLOGICAL CONSIDERATIONS

  • Patients may experience anxiety about surgery outcomes, affecting their physiological state and bleeding risk.

  • Maintaining a calm, supportive environment and providing reassurance during procedures is vital.

VERIFICATION OF THE OPERATIVE SITE

  • Universal Protocol mandates verification of the operative site and lens implants to prevent wrong implant insertion.

  • Steps include surgeon selection of intraocular lens (IOL), verbal confirmations of IOL details, and final verification before insertion.

POSITIONING THE PATIENT

  • Patients are typically placed in the supine position. Special attention is given to head stabilization and comfort to minimize movement during surgery.

PREPPING AND DRAPING

  • After anesthesia, skin prep is done with a dilute povidone-iodine solution, covering the eye area thoroughly.

  • Proper draping is crucial to isolate the surgical field.

  • BSS - balanced salt solution (irrigation)

  • 5% Povidone Iodine prep solution

ANESTHESIA

  • Regional anesthesia is preferred, using topical or infiltration methods, with general anesthesia for pediatric patients.

  • Retrobulbar block - cant move eye and cant see besides light changes

OPHTHALMIC DRUGS

  • Essential pharmaceuticals used in the surgical process, requiring strict labeling and documentation.

  • Common drugs include topical anesthetics, mydriatics, and anti-infectives.

  • Epinephrine - prolongs medication vasoconstrictor

INSTRUMENTS

  • Specialized ophthalmic instruments are essential, requiring careful handling to prevent damage during procedures.

  • Westcott Scissors

OPHTHALMIC SURGICAL TECHNIQUES

  • Techniques include microsurgery and careful instrument handling.

COMMON SURGICAL PROCEDURES

EXCISION OF A CHALAZION

  • Position: Supine

  • Incision: Conjunctival

  • Instruments: Chalazion set

  • Involves incision into the tarsal plate and removal of the chalazion contents with a curette.

DACRYOCYSTORHINOSTOMY

  • Position: Supine

  • Incision: Median canthus

  • Creation of an opening for amending tear drainage.

MUSCLE RESECTION AND RECESSION

  • Procedures for correcting strabismus by detaching and reattaching muscles appropriately.

PENETRATING KERATOPLASTY

  • Full-thickness corneal transplantation to restore vision.

EXTRACAPSULAR CATARACT EXTRACTION (PHACOEMULSIFICATION)

  • Removal of an opaque lens via ultrasonic fragmentation then replaced with an IOL implant.

ANTERRIOR VITRECTOMY

  • Techniques for removing vitreous from the anterior chamber, particularly following complications during cataract extraction.

SCLERAL BUCKLING FOR DETACHED RETINA

  • Techniques applied in cases of retinal detachment, utilizing cryotherapy or diathermy to promote attachment.

TRABECULECTOMY

  • Procedure to reduce intraocular pressure by creating drainage pathways for aqueous humor.

ENUCLEATION, EVISCERATION, AND EXENTERATION

  • Surgical approaches for treating severe ocular pathology with varying degrees of tissue removal.

REPAIR OF ENTROPION AND ECTROPION

  • Surgical corrections of inward and outward eyelid malposition.

PERIORBITAL LACERATIONS

  • Management of eyelid lacerations considering surrounding anatomical structures to prevent deeper tissue injury.

KEY CONCEPTS

  • Understanding of eye anatomy is essential for effective surgical practice.

  • Familiarity with diagnostic methods enhances patient care and understanding of surgical interventions.

  • Mastery of instrument and technique handling improves surgical outcomes.

REVIEW QUESTIONS

  1. Rationale for documenting lens implants in the medical record?

  2. Why do children experience nausea post-strabismus surgery?

  3. Methods to prevent ophthalmic needles from catching?

  4. Steps for verifying correct operative side in ophthalmic surgery?

  5. Locations of the anterior and posterior chambers?

  6. Emergency ophthalmic procedures discussed?

  7. Typical appearance of dehydrated eye tissues?

  8. Define trabeculectomy.

QUIZ REVIEW -

Sutures should be handled as little as possible

Enucleation - complete removal of eyeball- to treat intraocular malignancy such as retinoblastoma and melanoma

antieor vitrectomy may be indicated following cataract extraction

intravitreous gas - sulfur hexafluoride and perfluoro propane

lens is in the anterior chamber

cotton tip applicators

Scleral buckling - posterior cavity

Complete removal of eyeball and per