Vision Disorders

VISION DISORDERS

  • Vision disorders encompass a variety of conditions and complications that can affect visual acuity and overall ocular health.

    • Types of vision disorders include:

    • Eye trauma

    • Eye infection

    • Cataracts

    • Retinopathy

    • Retinal detachment

    • Macular degeneration

    • Glaucoma

ANATOMY AND PHYSIOLOGY

  • The anatomy of the eye is complex and includes the following components:

    • Trochlea: A fibrocartilaginous pulley for superior oblique muscle.

    • Levator palpebrae superioris: Muscle responsible for elevating the upper eyelid.

    • Superior oblique: A muscle that controls eye movement downward and laterally.

    • Superior rectus: Muscle that elevates the eye.

    • Lacrimal caruncle: Small, reddish body at the inner corner of the eye.

    • Lacrimal canals: Channels that transport tears.

    • Medial rectus: Muscle that controls eye movement inward.

    • Lateral rectus: Muscle that moves the eye outward.

    • Inferior oblique: Muscle that raises the eye while moving it outward.

    • Inferior rectus: Muscle that lowers the eye.

    • Puncta: Small openings for tear drainage.

    • Lacrimal sac: Collects tears before they drain into the nasolacrimal duct.

    • Lacrimal gland: Produces tears.

    • Canal of Schlemm: Drains aqueous humor from the anterior chamber to the bloodstream.

    • Lens: Transparent structure focusing light on the retina.

    • Iris: Colored part of the eye regulating pupil size.

    • Cornea: Transparent layer covering the front of the eye.

    • Anterior chamber: Space between the cornea and iris filled with aqueous humor.

    • Pupil: Opening in the iris that controls the amount of light entering the eye.

    • Posterior chamber: Space behind the iris filled with aqueous humor.

    • Suspensory ligament: Holds the lens in place.

    • Ciliary body: Produces aqueous humor and adjusts the lens shape.

    • Sclera: White part of the eye providing structure.

    • Choroid: Vascular layer supplying blood to the retina.

    • Vitreous humor: Gel-like substance maintaining eye shape.

    • Retina: Light-sensitive layer containing photoreceptors for vision.

    • Fovea centralis: Area of highest visual acuity.

    • Macula: Central area of the retina responsible for sharp vision.

    • Optic nerve: Transmits visual information to the brain.

    • Optic disc: Point where the optic nerve enters the eye.

    • Posterior cavity: Space filled with vitreous humor.

EYE TRAUMA

  • Types of eye trauma can include:

    • Blunt trauma: Injury caused by a force that does not penetrate the tissue.

    • Penetrating trauma: Injury caused by an object that pierces the eye.

    • Chemical burns: Damage caused by toxic substances entering the eye.

    • Thermal burns: Eye injury resulting from extreme heat.

    • Foreign bodies: Objects that become lodged in the eye.

  • Clinical Manifestations of Eye Trauma:

    • Pain

    • Redness

    • Swelling

    • Ecchymosis (bruising)

    • Tearing

    • Photophobia (sensitivity to light)

    • Blood or fluid drainage (e.g., aqueous humor)

    • Changes in vision

    • Prolapsed globe (protrusion of the eyeball)

  • Common Causes of Eye Trauma:

    • Falls and fights

    • Cleaning activities

    • Gardening

    • Power tools usage

    • Sports and work-related incidents

  • Collaborative and Nursing Care for Eye Trauma:

    • Determine the mechanism of injury to inform treatment.

    • Assess ABCs (Airway, Breathing, Circulation) and other possible injuries.

    • Perform ocular irrigation immediately for chemical exposures.

    • Stabilize and refrain from removing foreign objects.

    • Do not apply pressure to the eye.

    • Provide analgesia as needed for pain management.

    • Keep the head of the bed (HOB) elevated at 45 degrees.

    • Advise the patient to avoid blowing their nose.

    • NPO status (nothing by mouth) may be required for potential surgery.

INFLAMMATION AND INFECTION

  • Common forms of inflammation and infection include:

    • Sty (External hordeolum):

    • Infection of the meibomian glands usually caused by Staphylococcus aureus.

    • Blepharitis:

    • Chronic bilateral inflammation of the eyelid margins due to bacteria or inflammation.

    • Conjunctivitis:

    • Inflammation or infection of the conjunctiva, which can be further categorized as:

      • Bacterial: caused by organisms such as Staphylococcus and Chlamydial trachomatis.

      • Viral: often caused by adenovirus (Epidemic keratoconjunctivitis, EKC).

      • Allergic: resulting from allergic reactions.

  • Treatment Options:

    • Sty:

    • Utilize warm, moist compresses four times daily.

    • Blepharitis:

    • Implement gentle cleansing practices; antibiotic ointment may be necessary for bacterial infections to prevent keratitis (inflammation of the cornea).

    • Conjunctivitis:

    • Bacterial: usually self-limiting, antibiotics can shorten the course; handwashing and avoiding contact with infected individuals are critical.

    • Chlamydial: requires antibiotic therapy.

    • Viral: generally self-limiting; cool compresses can aid in symptoms; prevention of transmission is crucial.

    • Allergic: avoid allergens, use artificial tears, and potentially antihistamines.

CATARACTS

  • Definition: Cataracts are characterized by the opacity of the lens, which can occur unilaterally or bilaterally. When the lens is not transparent, patients experience changes in vision.

  • Etiology: Cataracts are generally age-related.

  • Clinical Manifestations:

    • Gradual decline in vision.

    • Abnormal color perception.

    • Increased glare, particularly at night.

  • Comparative Visualization:

    • Normal Eye: A healthy lens enables all parts of the retina to receive a clear image.

    • Cataract Eye: A cloudy lens scatters light, resulting in images that are out of focus and hazy.

  • Interprofessional Care for Cataracts:

    • Nonsurgical Therapy:

    • Update prescription glasses.

    • Increase lighting in various environments.

    • Advise against driving at night to prevent accidents.

    • Surgical Therapy:

    • Phacoemulsification: The most common procedure for cataract removal.

    • Extracapsular cataract extraction: A method of removing the lens while leaving the capsule intact.

  • Preoperative Care:

    • Administer local anesthesia along with nonsteroidal anti-inflammatory drops and dilating drops (which may include mydriatic and cycloplegic agents).

    • Bear in mind that dilating drops can cause photophobia; therefore, ambient light should be reduced.

  • Postoperative Care:

    • Patients often go home shortly after the procedure.

    • Educate patients about medication regimens, particularly regarding antibiotic and corticosteroid drops.

    • Emphasize the avoidance of bending, stooping, coughing, or lifting to minimize strain on the eyes.

    • Scratchiness and blurriness are common post-surgery; however, intense pain may indicate complications.

  • Nursing Implementation:

    • Educate patients and caregivers on proper hygiene and eye care techniques to ensure that medications and dressings remain uncontaminated.

    • Discuss signs and symptoms of infection, including increased or purulent drainage, redness, or any drop in visual acuity and the procedure for early reporting.

    • Stress the importance of head positioning, bending, and cough restrictions to optimize visual outcomes and prevent increased intraocular pressure (IOP).

    • Teach patients how to properly instill eye medications using aseptic techniques and adherence to the prescribed medication regimen.

    • Advise on pain management strategies and how to report any pain not alleviated by medications.

    • Highlight the necessity of ongoing follow-ups to maximize visual recovery.

RETINOPATHY

  • Definition: Retinopathy refers to microvascular damage to the retina typically associated with diabetes and hypertension.

    • Diabetic Retinopathy:

    • Nonproliferative: This is the most common form, characterized by capillary microaneurysms, retinal swelling, and hard exudates.

    • Proliferative: An advanced stage where fragile new blood vessels grow and are susceptible to leaking.

    • Hypertensive Retinopathy: Results in blockages within retinal blood vessels due to chronic hypertension.

RETINAL DETACHMENT

  • Definition: Retinal detachment occurs when the sensory retina detaches from the pigmented epithelium, typically accompanied by fluid accumulation between layers.

  • Clinical Manifestations:

    • Photopsia (flashes of light).

    • Floaters in the vision field.

    • Appearance of a “cobweb” or “hairnet” effect in vision.

    • Sudden vision loss described as looking through a curtain.

    • Vision loss that correlates inversely with the degree of detachment.

  • Surgical Therapy Options:

    • Laser photocoagulation: Uses laser to seal retinal tears.

    • Cryopexy: A freezing process to adhere the retina back.

    • Scleral buckling: A surgical procedure that involves placing a buckle on the sclera to close the break and alleviate detachment.

AGE-RELATED MACULAR DEGENERATION (AMD)

  • Etiology & Pathophysiology:

    • Dry AMD: Characterized by the atrophy of macular cells, leading to slow but progressive vision loss. This is the more common type of AMD.

    • Wet AMD: Displays a rapid onset of vision loss due to abnormal angiogenesis, where new fragile blood vessels leak fluid and bleed, resulting in scarring over the macula.

  • Clinical Manifestations:

    • Presence of scotomas (blind spots in the visual field).

    • Metamorphopsia: A condition where straight lines appear distorted.

    • Loss of central vision, severely impacting daily activities.

  • Interprofessional Care for AMD:

    • For Wet AMD: Treatment involves injections of medications into the vitreous cavity every 4-6 weeks (e.g., Ranibizumab (Lucentis), Bevacizumab (Avastin), Aflibercept (Eylea), Pegaptanib (Macugen)) to slow vision loss by inhibiting the formation of abnormal blood vessels. Alternately, photodynamic therapy (PDT) may be employed using Verteporfin (Visudyne) to damage the abnormal vessels.

    • For Dry or Wet AMD: Consider nutritional factors and dietary supplements to support eye health, promote smoking cessation (especially important for dry AMD), and recommend low vision assistive devices to enhance patient independence.

GLAUCOMA

  • Definition: Glaucoma represents a group of eye disorders characterized by increased intraocular pressure (IOP) exceeding normal values (10-21 mm Hg). This condition can lead to optic nerve atrophy and substantial peripheral vision loss, particularly affecting the elderly populace and certain ethnicities (leading cause of blindness among blacks).

  • Pathophysiology: The production of aqueous humor ("inflow") surpasses the reabsorption (\