Eye and Ear Disorders Notes

Anatomy of the Eye

  • Basic Structures:
    • Iris: Colored part of the eye that controls the size of the pupil.
    • Lens: Transparent structure that focuses light onto the retina.
    • Aqueous Humor: Fluid in the anterior chamber; maintains intraocular pressure.
    • Cornea: The clear front surface of the eye that helps focus light.
    • Sclera: The white part of the eye, providing protection and structure.
    • Choroid: Layer containing blood vessels that nourish the eye.
    • Retina: The light-sensitive tissue at the back of the eye.
    • Vitreous Body: Gel-like substance filling the eye, maintaining its shape.
    • Optic Nerve: Transmits visual information from the retina to the brain.

Diagnostic Stains

  • Uses:
    • Locate extraocular lesions or foreign objects.
    • Evaluate dry eyes or extraocular changes.
    • Enhance details during examinations.
  • Nursing Interventions:
    • Staining may discolor external eye or nasal secretions.
    • Rinse the eye with normal saline post-procedure.
    • Soft contact lenses can be replaced after 1 hour.

Topical Anesthetics

  • Uses:
    • Facilitate comprehensive eye exams and ophthalmic procedures.
  • Mechanism:
    • Block pain signals at the eye's nerve endings.
    • Corneal anesthesia typically achieved within 15 seconds and lasts ~15 minutes.

Anti-infectives

  • Uses:
    • Treatment of various eye infections, including:
    • Conjunctivitis
    • Blepharitis
    • Chalazion
    • Endophthalmitis
    • Hordeolum
    • Infectious Keratitis
    • Infectious Uveitis

Anti-inflammatories

  • Types:
    • Cyclosporine
    • Ophthalmic NSAIDs: Diclofenac, Ketorolac
    • Corticosteroids: Dexamethasone, Prednisolone
    • Antihistamines and Mast Cell Stabilizers

Decongestants

  • Action:
    • Stimulate alpha-adrenergic receptors, reduce redness by narrowing conjunctival blood vessels.
  • Examples:
    • Phenylephrine, Naphazoline, Tetrahydrozoline
  • Contraindication:
    • Angle-closure glaucoma

Lubricants

  • Use:
    • Moisturize eyes to relieve burning and irritation.
    • Useful for contact lenses and artificial eyes.

Glaucoma and Ocular Hypertension Drugs

  • Types of Glaucoma:
    • Open-angle glaucoma: Trabecular meshwork is clogged; gradual increase in intraocular pressure (IOP).
    • Closed-angle glaucoma: Iris blocks drainage angle preventing aqueous humor from draining; sudden increase in IOP.

Treatment Options

  • Medications:
    • Prostaglandin Analogues: Increase outflow of aqueous humor (e.g., Bimatoprost, Latanoprost).
    • Beta-Adrenergic Blockers: Decrease aqueous humor production (e.g., Timolol).
    • Cholinergic Agents: Enhance outflow (e.g., Pilocarpine).
    • Carbonic Anhydrase Inhibitors: Decrease production (e.g., Dorzolamide).
    • Alpha-Adrenergic Blockers: Control IOP (e.g., Brimonidine).

Side Effects Overview

  • Prostaglandin Analogues:
    • Side effects include iris color change, ocular hyperemia, and eyelash changes.
  • Beta-Blockers:
    • May cause bradycardia or bronchoconstriction.
  • Cholinergic Agents:
    • Can cause ocular irritation and increased risk of retinal detachment.

Mydriatics and Cycloplegics

  • Mydriatics: Dilate pupils for exams;
  • Cycloplegics: Paralyze accommodation muscles.
  • Side Effects:
    • Commonly include dry eyes, blurred vision, and headache.

Drugs for Macular Degeneration

  • Condition: Deterioration of the macula, leading to vision loss.
  • Types:
    • Wet: Fast progression due to abnormal blood vessel growth; treated with VEGF inhibitors (e.g., Ranibizumab).
    • Dry: Gradual vision loss, no cure available.

Anatomy of the Ear

  • Basic Structures:
    • Auricle: External part of the ear.
    • Cochlea: Spiral-shaped structure important for hearing.
    • Eustachian Tube: Equalizes pressure in the ear.

Drugs for Ear Disorders

  • Anti-infectives: Used for acute otitis media and externa (e.g., Amoxicillin).
  • Side Effects: Burning, stinging, and potential for ototoxicity.

Patient Education for Ear Disorders

  • Complete prescribed medication courses and understand the importance of culture testing.
  • Educate about ceruminolytics for earwax removal, including both water-based and oil-based options.

Practice Questions

  • Correct Eardrop Administration: Pull down on auricle for young children.
  • Pilocarpine Action: Causes miosis (pupil constriction).

Clinical Judgment in Eye and Ear Drug Therapy

  • Continuous monitoring for adverse effects, checking visual acuity and IOP in glaucoma patients, and avoiding abrupt discontinuation of therapy for patient safety.