Chapter 18: Ophthalmic Surgery Comprehensive Study Guide

Learning Objectives for Ophthalmic Surgery

  • Anatomy Identification: Recognize the anatomy of the eye.

  • Pathology and Terminology: Summarize the pathology that prompts surgical intervention of the eye and the related terminology.

  • Preoperative Preparation: Determine any special preoperative preparation procedures.

  • Instruments and Pharmacology: Indicate the names and uses of ophthalmic instruments, supplies, and drugs.

  • Special Equipment: Indicate the names and uses of special equipment.

  • Intraoperative Management: Determine the intraoperative preparation of the patient undergoing an ophthalmic procedure.

  • Surgical Steps: Summarize the surgical steps of ophthalmic procedures.

  • Purpose and Outcomes: Interpret the purpose and expected outcomes of the ophthalmic procedure.

  • Postoperative Care: Recognize the immediate postoperative care and possible complications of the ophthalmic procedure.

  • Specific Variations: Assess any specific variations related to the preoperative, intraoperative, and postoperative care of the ophthalmic patient.

Anatomy of the Orbital Cavity

  • The orbital cavity is comprised of several bones and fissures that protect the globe:
        - Frontal bone: Forms the upper portion of the orbit.
        - Optic foramen: The opening through which the optic nerve passes.
        - Ethmoid bone: Located on the medial wall.
        - Superior orbital fissure: A gap between the greater and lesser wings of the sphenoid bone.
        - Sphenoid bone: Forms part of the posterior wall.
        - Zygomatic bone: Forms the lateral wall and cheek area.
        - Lacrimal bone: Small bone in the medial wall.
        - Maxilla: Forms the floor of the orbit.
        - Infraorbital foramen: An opening in the maxillary bone below the orbit.
        - Inferior orbital fissure: Located in the floor of the orbit.

Anatomy of the Globe (Eyeball)

  • External Structures:
        - Pupil: The central opening of the iris.
        - Lacrimal caruncle: Small, pink, globular nodule at the inner corner (canthus) of the eye.
        - Cornea: A clear, transparent tissue layer overlying the front of the eyeball.
        - Iris: The colored part of the eye that divides the anterior and posterior chambers.
        - Lower lid: Protective fold of skin.

  • Internal Components:
        - Lens: A biconcave, clear structure encompassed by a transparent capsule; located directly behind the iris.
        - Anterior chamber: Contains aqueous humor; located in front of the iris.
        - Posterior chamber: Contains aqueous humor; located posterior to the iris but anterior to the lens.
        - Ciliary body: An extension of the choroid at the periphery of the anterior choroid; contains smooth muscle for suspensory ligament attachment.
        - Vitreous: The clear gel (vitreous humor) that fills the space between the lens and the retina of the eyeball.
        - Retina: The innermost layer of the posterior globe.
        - Choroid: A vascular pigmented layer lying beneath the sclera; prevents light reflection within the eyeball.
        - Sclera: Thick, white, fibrous tissue that encloses approximately three-fourths of the eyeball.
        - Optic disc: The point of exit for ganglion cell axons leaving the eye.
        - Optic nerve: Transmits visual information from the retina to the brain.
        - Fovea and Macula lutea: Areas of the retina responsible for sharp central vision.
        - Visual axis: The line passing through the center of the lens and the fovea.
        - Central artery and vein: Provide blood supply to the retina.

Special Anatomical Details

  • Conjunctiva:
        - A thin, transparent mucous membrane.
        - Lines each eyelid and covers the sclera.
        - Divided into the palpebral region (lining the lids) and the bulbar region (covering the globe).

  • Lacrimal Apparatus: Composed of the lacrimal gland, ducts, sac, and nasolacrimal duct for tear production and drainage.

Physiological Principles

  • Refraction: The bending of light rays as they pass through a transparent medium.

  • Focal Point: The specific location where light rays converge.

  • Accommodation: The active process of focusing the eye to maintain a clear image at various distances.

Ocular Diseases and Psychological Considerations

  • Categories of Disorders:
        - Damage to one or both chambers.
        - Irregularities of the epithelial surface.
        - Retinal and choroid diseases.
        - Eye tissue abnormalities.
        - Issues within orbital structures.

  • Psychological Factors:
        - Surgeons and staff must create a relaxing environment.
        - Patients often experience fear and a lack of control.
        - Blindness is a possible complication, heightening anxiety.
        - Procedures are commonly performed under conscious sedation.
        - Because the patient is awake, staff must be mindful of conversations.
        - Patients must consciously override the normal reflex to pull away during the procedure.

Perioperative Preparation and Verification

  • Operative Site Verification:
        - Responsibility of the entire surgical team.
        - The Joint Commission recommends the surgeon mark the skin near the operative site.
        - Always check with the patient for the correct procedure and site.

  • Patient Positioning:
        - Position: Supine.
        - Head: Stabilized in a donut headrest.
        - Comfort: Pillow placed under the knees.

  • Prep and Draping:
        - The canthus of the eye is considered contaminated.
        - Draping must isolate the hairline and the nonoperative side.

  • Surgical Counts:
        - Must include sutures.
        - Needle tips (notably small in ophthalmic surgery).
        - Blades.
        - Weck Spears (specialized eye sponges).

Ophthalmic Pharmacology and Anesthesia

  • Medication Management:
        - Medications are instilled or injected before, during, and after surgery.
        - Items must be labeled as soon as they reach the sterile field.
        - All medications must be identified and acknowledged with the surgeon.
        - All drugs must be recorded on the operative report.

  • Anesthesia Types:
        - Regional anesthetic with monitored sedation is common for adults.
        - Retrobulbar block: Regional anesthesia injected behind the globe.
        - Pediatric patients require general anesthetic.

Ophthalmic Instrumentation and Equipment

  • Cutting Instruments:
        - Scalpels: Graefe cataract knife, Keratomes (often disposable), Razor fragments, Diamond knife, Beaver blades, and the No. 15 knife blade.
        - Scissors: Specifically designed for fine ocular tissue.

  • Forceps:
        - Bishop-Harmon iris forceps.
        - Desmarres chalazion forceps.
        - Colibri forceps.
        - Non-tooth forceps.

  • Misc. Instruments:
        - Bowman probe.
        - Caliper.
        - Needle holder.

  • Hooks and Retractors:
        - Scleral hooks: Used for scleral retraction.
        - Kilner hook: Used in reconstructive surgery.
        - Desmarres lid retractors.
        - Iris retractor.
        - Eye speculum.

  • Specialized Systems:
        - Electrosurgical unit (ESU).
        - Phacoemulsifier / Vitreoretinal systems.
        - Microscope.
        - Lasers.

Microsurgery Standards

  • The Operating Microscope:
        - Adjusted for height and placement by the surgeon just before scrubbing.
        - Requires draping or sterile knobs, performed after patient prep and drape.

  • Scrub Role in Microsurgery:
        - The surgeon’s field of vision is magnified and the scope (area of vision) is very limited.
        - The surgeon cannot look away from the field; the scrub must prepare ahead for each step.
        - The scrub must prevent any movement of the microscope.

Specific Ophthalmic Procedures

  • Eye Muscle Surgery (Strabismus): Corrects misalignment of the eyes.

  • Excision of Chalazion:
        - Pathology: A chalazion is an inflammatory, benign growth originating in a sebaceous gland of the eyelid.
        - Step: Nodal tissue arising from a sebaceous gland is excised from the tarsal plate.

  • Nasolacrimal Duct Probing/Stenting: Performed to clear obstructions in the tear drainage system.

  • Dacryocystorhinostomy (DCR): Creation of a new tear drainage pathway between the lacrimal sac and the nose.

  • Excision of a Pterygium: Surgical removal of the pterygium membrane to prevent vision loss.

  • LASIK (Laser In Situ Keratomileusis): Reshaping the curvature of the cornea to correct refractory problems.

  • Cataract Extraction:
        - Pathology: Removal of an opaque lens.
        - Causes: Aging, trauma, glaucoma, medications, congenital anomalies, or radiation exposure (sunlight/X-rays).
        - Phacoemulsification: Fragmentation of tissue through ultrasonic vibration.

  • Anterior Vitrectomy: Removal of vitreous fluid from the anterior chamber using a vitrector, irrigation cannula, and viscoelastic.

  • Scleral Buckling: Performed for a detached retina when the sensory layer separates from the pigment epithelial layer.

  • Glaucoma Procedures:
        - Glaucoma Types: Primary angle-closure, Open-angle (chronic), Secondary, and Congenital.
        - Iridectomy: Surgical removal of part of the iris; the hole allows fluid to flow normally.
        - Trabeculectomy: Removal of part of the trabecular meshwork to relieve intraocular pressure.
        - Argon Laser Trabeculoplasty: Uses laser to shrink collagen and stretch the canal of Schlemm to increase drainage.

  • Enucleation: Complete removal of the eyeball.
        - Step 1: 360∘360^{\circ} peritomy performed.
        - Step 2: Removal of the cornea.
        - Step 3: Removal of ocular contents (Lid speculum placed).
        - Step 4: Incisions made in the sclera for implant.
        - Step 5: Orbital implant inserted.
        - Step 6: Sclera and conjunctiva sutured over the implant.