chapter 25

Ophthalmic Surgery Study Notes

Chapter 25

Key Terms to Know

  • Accommodation: The process by which the eye adjusts its focus for varying distances.

  • Cataract: A clouding of the lens of the eye leading to decreased vision.

  • Enucleation: The surgical removal of the eyeball, leaving the muscles and orbit intact.

  • Evisceration: Removal of the contents of the eye, retaining the scleral shell.

  • Exenteration: Removal of the eye, optic nerve, and surrounding muscles.

  • Keratoplasty: Surgery to reconstruct or replace the cornea.

  • Muscle recession: A procedure to correct strabismus by repositioning the eye muscles.

  • Strabismus: A condition where the eyes do not properly align with each other.

  • Refraction: The bending of light as it passes through the eye to focus.

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

Anatomy Review

  • Eye Globe:

    • Consists of two main cavities: anterior and posterior.

    • Contains six extraocular muscles:

    • Four rectus muscles.

    • Two oblique muscles.

  • Conjunctiva: A thin, clear mucous membrane covering the eye.

  • Cornea: A clear, dome-shaped tissue that forms the front of the eye.

  • Sclera: A thick, white, fibrous outer layer that constitutes three-quarters of the eye.

  • Choroid/Ciliary Body: Functions to prevent reflection and provide nourishment to the retina.

  • Iris: A pigmented membrane that controls the size of the pupil.

  • Retina: The innermost layer at the posterior of the eye, responsible for sensing light.

  • Lens: Located directly behind the iris, focuses light onto the retina.

Cavities of the Eye

  • Posterior Cavity:

    • Contains the vitreous body, a gel-like substance.

  • Anterior Cavity:

    • Contains the anterior and posterior chambers filled with aqueous humor.

Ophthalmic Instrumentation and Equipment & Supplies

  • Equipment & Supplies:

    • Battery-powered & Bipolar Cautery: Used for cutting and coagulating tissues.

    • Eye Sponges: Lint-free cellulose sponges utilized in ophthalmic procedures; not to be used directly on the cornea.

    • Sutures: Range from size 4-0 to 12-0, double-armed for circumferential incisions; handled minimally to avoid contamination.

    • Dressings: Rigid eye shields and soft dressings used post-operatively.

Chalazion

  • Definition: An inflammatory benign growth arising from a sebaceous gland blockage.

  • Instruments Used:

    • Chalazion Clamp

    • Beaver Knife

    • Westcott Scissors

Dacryocystorhinostomy

  • Procedure Description:

    • Creates an opening for tear drainage from the tear duct into the sinus.

    • Related Condition: Dacryocystitis, which is inflammation of the lacrimal sac.

Resection and Recession for Strabismus

  • Definition: Surgical procedures to correct misalignment of the eyes, allowing them to focus better.

  • Types of Procedures:

    • Lateral Rectus Resection: Involves shortening the lateral rectus muscle.

    • Medial Rectus Recession: Involves moving the medial rectus muscle back.

  • Support Methods:

    • Bridle (traction) sutures are used to position the eye appropriately.

    • Muscles are measured using a caliper and spatula needles for precision.

Keratoplasty

  • Definition: A corneal transplant procedure, restoring vision in patients with corneal damage.

  • Types:

    • Partial Thickness (Lamellar): Only part of the cornea is replaced.

    • Full Thickness (Penetrating): Entire cornea is replaced.

  • Setup Details:

    • Requires two preparative setups, one for the transplant and another for the donor.

    • Use of a trephine to cut both the cornea and donor cornea.

    • Sodium hyaluronate is injected to replace fluid in the anterior chamber.

Cataract Surgery: Phacoemulsification

  • Procedure Description:

    • Removal of opaque lens using ultrasonic vibrations.

  • General Info:

    • Most common ophthalmic surgical technique.

    • Conscious Sedation: Used during the procedure.

    • Injections Used: Healon and BSS (Balanced Salt Solution) administered for hydrodisection.

  • Commonality: Age-related cataracts are the most prevalent form.

Scleral Buckling for Retinal Detachment

  • Procedure Overview:

    • Involves placing a silastic band or buckle around the sclera to repair retinal detachment.

    • Causes contact between the retinal layers for proper healing.

  • Associated Techniques:

    • Vitrectomy: Removal of gel-like vitreous body helps eliminate traction and tearing.

    • Sutures hold the band in place, with gases infused for internal pressure, such as Sulfur hexafluoride (SF6) and Perfluoropropane (C3F8).

Trabeculectomy

  • Procedure Overview:

    • Creation of a drainage channel for aqueous humor, commonly used for glaucoma treatment.

    • Addresses optic nerve damage and visual field loss.

  • Types of Glaucoma:

    • Closed Angle: Represents about 30% of cases.

    • Open Angle: Associated with elevated tension.

  • Surgical Details:

    • Scleral flap is created, and a flat bleb must be formed.

    • The trabecular meshwork and canal of Schlemm are involved in the drainage process.

Procedures of the Globe: Enucleation and Evisceration

  • Enucleation:

    • Complete removal of the eyeball while retaining orbital fat and muscles.

    • Common Indications: Malignancy, penetrating wounds, blindness.

    • An intraocular implant (e.g., polyethylene or hydroxyapatite) is used post-surgery, with rectus muscles sutured to obliques.

  • Evisceration:

    • Involves removing the contents of the eyeball while leaving the scleral shell intact.

    • May involve fitting an intraocular prosthetic.

Eyelid Repairs

  • Entropion: Inward turning of the eyelid, causing irritation.

  • Ectropion: Outward drooping of the eyelid, which may expose the conjunctiva.

  • Bells Palsy: Affects eyelid function, leading to potential surgical interventions to correct changes in eyelid position.