Visual Acuity Disorders: Refraction and Errors

• Visual acuity disorders can be:
  • Refraction
  • Refractive Errors
  • Myopia (Nearsightedness)
  • Hyperopia (Farsightedness)
  • Astigmatism
  • Presbyopia

Refractions

• A key eye function that allows for clear vision at different distances
• The cornea and the lens bend light rays to focus images correctly onto the retina

Refractive Errors

• Occur when the eye can't properly focus light on the retina
• Main types include myopia, hyperopia, astigmatism, and presbyopia

Myopia (Nearsightedness)

• The eyeball is too long or the cornea is too curved, causing the focused image to fall in front of the retina
• About 25% of the US population has Myopia

Hyperopia (Farsightedness)

• The opposite of myopia where the image focuses behind the retina
• About 25% of the U.S population is affected with equal impact on men and women
• It happens when the eyeball is shorter than normal, causing light rays from close objects to focus behind the retina
• Linked to heredity and increased age
• Many babies are slightly hyperopic, but this often corrects as they grow

Astigmatism

• Caused by a misshapen cornea
• Often occurs with myopia or hyperopia, and most people have some degree of it
• Caused by heredity or injury that distorts the lens or cornea
• Trauma, scarring, surgical procedures, keratoconus, and diabetes are other causes
• The lens or cornea is curved more steeply in an oval shape, which prevents light rays from focusing on a single point on the retina

Presbyopia

• Related to aging where the lens loses elasticity, typically occurring around age 45
• Considered a normal part of aging and nearly everyone experiences it to some degree by their mid-40s
• Results from the loss of lens elasticity, making focusing on close objects harder
• Reading glasses or handheld magnifiers are corrective measures

Diagnosis

• An initial diagnosis can be done by using a Snellen chart in a general provider's office
• Further assessments and exact diagnoses are performed by eye care professionals, such as ophthalmologists or optometrists
• Relies on eye examinations and visual acuity measurements, often using Snellen charts, or more detailed exams by eye care professionals

Treatment

• Refractive disorders can usually be corrected with prescriptive lenses, i.e. eyeglasses or contact lenses

Epidemiology

• Refractive errors affect approximately one-third of people 40 years or older in the US

Pathophysiology

• The shape of the eye and the cornea are key to focusing
• Myopia, hyperopia, astigmatism, and presbyopia are the primary disorders of visual acuity

Medical Management

• Medical management of visual acuity disorders aims to improve vision as much as possible, primarily through corrective lenses

Orthokeratology

• A non-surgical method to reshape the cornea
• Involves wearing special contact lenses that gradually reshape the cornea, that can correct myopia (nearsightedness) over time

Surgical options

• Common surgical treatments for visual acuity disorders include different approaches to:
  • Keratotomy: Cutting into the cornea
  • Keratectomy: Surgical removal of a section or layer of the cornea
  • Keratoplasty: Replacing damaged corneal tissue with healthy donor tissue

Specific Surgical Procedures

• Radial Keratotomy (RK): Tiny incisions are made in the cornea to flatten it, reducing the refractive error
• Photorefractive Keratectomy (PRK): A portion of the cornea is removed with a laser to change its shape and correct the refractive error
• Laser-Assisted In Situ Keratomileusis (LASIK): A laser or microkeratome is used to create a flap in the cornea.
  • The flap is folded back, corneal tissue is removed with a laser, and the flap is repositioned
  • UV light is used to reshape the cornea
• Laser Thermal Keratoplasty (LTK): A Holmium laser (infrared or thermal laser) is used to reshape the cornea by using heat to shrink the corneal tissue
• Conductive Keratoplasty (CK): Radiofrequency energy is applied to specific points on the cornea's periphery using a tiny probe that causes the collagen to contract, shrinking the circumference of the cornea and changing its shape

Non-Surgical Corrections

• Hyperopia: Uses glasses/contact lenses and specifically convex lenses
• Presbyopia: Uses reading glasses or magnification
• Astigmatism: Uses eyeglasses, contact lenses, or Orthokeratology
• Myopia: Uses Radial keratotomy, photorefractive keratectomy, and LASIK
• Refractive surgery and implanted intraocular lenses are options
  • Other therapies are also being investigated

LASIK

• Stands for Laser-assisted in situ keratomileusis

Assessment and Analysis

• The approach to treating visual acuity disorders differs significantly based on the specific diagnosis

Treatment Options

• The four main visual acuity disorders can be managed medically using corrective eyeglasses or contact lenses
• Surgical options are also available for each disorder

Individualized Care

• Treatment plans are tailored to the individual patient, taking into account factors like expected outcomes, age, and personal circumstances

Visual Acuity Nursing Considerations

• Nursing diagnoses or potential problems:
  • Disturbed visual sensory perception, related to changes in how a person perceives their environment due to refractive errors
  • Risk for injury because the difficulty in focusing can increase the risk of accidents and injuries
  • Anxiety, because visual impairment and the inability to focus can lead to anxiety
  • Possible disruption of activities of daily living Visual disturbances can interfere with everyday tasks and activities.
  • Refraction errors: A broad term referring to the underlying visual problem.

Visual Acuity Nursing Interventions

• Vital signs are not usually affected by visual acuity disorders themselves
• Elevated pulse and blood pressure are more likely related to pain or anxiety. Physical assessments focus on corneal shape changes in myopia, hyperopia, and astigmatism

Ophthalmology Considerations

• Changes in myopia, hyperopia, and astigmatism result in corneal shape changes
• Presbyopia shows changes in lens elasticity, resulting in a more elongated lens

Other indicators

• Myopia: Blurred vision when looking at distant objects, headaches, feeling of eye strain, squinting when looking at objects more than a few feet away
  • Hyperopia: Blurred vision when looking at close-up objects, aching eyes or feeling of eye strain, headache during reading.
  • Presbyopia: Holding reading material far away to see clearly, blurred vision at normal reading distance, eye strain or headaches after reading or close work (may also occur with myopia and hyperopia).
  • Astigmatism: Headache, blurred vision at all distances, feeling of fatigue or eye strain.

Ensure Correcting Lenses are worn

• Important because these lenses correct refraction errors Provide Adequate Lighting: Sufficient lighting is crucial for maximizing visual acuity

Patient Teaching points

• The need to wear eyeglasses or contact lenses as prescribed
  • Review proper care, cleaning, disinfection, insertion, and storage of contact lenses and eyeglasses
  • Contact lens wearers should remove lenses at night to prevent eye damage, unless they use extended-wear lenses Report Visual Changes and Headaches: Instruct patients to inform their healthcare provider about any new visual disturbances or persistent headaches, as this could mean their current lens correction isn't adequate.
• Yearly follow-up with a provider is recommended for all patients with corrective lenses.
• Report increased pain, temperature, or unusual feelings, as these may indicate a complication or infection
  • Emphasize the importance of follow-up appointments for proper healing
• Explain any restrictions on lifting, bending, and Valsalva maneuvers to prevent increased intraocular pressure (IOP), if applicable to their surgery.

Evaluating Care Outcomes

• Successful treatment relies on understanding potential complications and following specific postoperative instructions, if surgery was performed Patients with visual acuity disorders can still live full and active lives

Importance of Follow Up

• Continuous monitoring by a health care provider is essential to maintain the best possible vision.
• Magnification needs may change over time Opioid Crisis: Opioid use and related deaths in the U.S have significantly increased since 2000

Endogenous Endophthalmitis

• A severe complication of IV opioid use is endogenous endophthalmitis, an infection that enters the bloodstream and spreads to the eye Injection drug use with nonsterile equipment can cause bacterial, fungal, or viral bloodstream infections that spread to the eye Despite treatment, about 50% of those affected lose all light perception, and the condition can lead to partial or complete blindness: Patients may have subtle signs, including a red and painful eye, sensitivity to light (photophobia), floaters (spots in vision), and reduced vision.

Conjunctivitis

• A general term for inflammation of the conjunctiva, or the membrane covering the eye, and commonly known as pinkeye Can be caused by various factors and occurs worldwide, affecting all ages, races, genders, and socioeconomic Status

Risk factors

• Can be sporadic or linked to epidemic outbreaks
• A National Health Survey found the prevalence of conjunctivitis in the U.S. to be about 13 per 1,000 people aged 1 to 74
• Conjunctivitis accounts for approximately 30% of eye-related emergency department visits, which are 3% of all emergency department visits Prevention: Routine hygiene practices reduce the transmission of conjunctivitis

Allergic Conjunctivitis

• Triggered by allergens such as pollen or dander, leading to inflammation • Symptoms include red or pink sclera, intense itching, burning, tearing, and swollen eyelids

Bacterial Conjunctivitis

• Typically caused by a bacterial infection of the conjunctiva • Patients often report a gritty or sandy feeling in the eye • Commonly involves a purulent discharge and matted eyelashes upon waking up

Viral Conjunctivitis

• Inflammation due to a viral infection • Often seen with common colds, upper respiratory infections, and sore throats • The eye typically has a watery discharge, and the condition is easily spread from one eye to the other

Chlamydial Conjunctivitis

• A sexually transmitted infection (STI) spread through hand-to-eye contact with infected genital secretions or during birth from an infected mother • the causative organism is Chlamydia trachomatis • May last for weeks or months

Contact Lens-Related Conjunctivitis

• Caused by hypersensitivity to chemicals in contact lenses or lens solutions • Can also result from dirty lenses or debris under the lens

Mechanical Conjunctivitis

• Irritation of the conjunctival surface from an eyelash, foreign body, or other irritant

Traumatic Conjunctivitis

• Results from a more direct injury such as laceration, abrasion, or chemical exposure considered a secondary response

Toxic Conjunctivitis

• Develops following administration of a medication or direct contact with a corrosive or noxious chemical

Medical Management

• Treatment plan depends on the cause of the infection

Comprehensive history

• Gathering a thorough patient history is crucial; a complete patient history will determine the type of conjunctivitis and guide most effective treatment
• In some cases, a culture is needed
• Visual acuity is always checked before and after treatment

Assessment and Analysis

• A thorough patient history is critical for an accurate diagnosis because many types share similar signs and symptoms:
  • Tearing
  • Itching
  • Inflammation of the conjunctiva General Treatment Strategies: • Topical steroid and mast cell stabilizing drops instilled directly into the eye decrease the inflammation and block any histamine release • Removal of the offending allergen, if it can be identified • Topical vasoconstrictor-Anti-histamine drops to relieve the intense itches • Frequent and proper hand-washing helps prevent the spread of bacteria

Treatment by type

• Bacterial Conjunctivitis: Administration of antibiotic eye drops or ointment; systemic antibiotics are rarely necessary • Good hand washing practices remain of importance - Viral Conjunctivitis: Treatment mainly involves using cooler compresses, eye lubricants, and ocular decongestants to relieve certain symptoms such as swelling and even irritation. Good hand washing practices are helpful to prevent the disease from spreading to other people
• Chlamydial Conjunctivitis: Systemic antibiotics have to be typically prescribed for a period of one month.

Contact Lens

• Contact Lens: Stop insertion of contacts and identify any reactions to them. The patient must throw away lens in the case they are contaminated. Good hand-washing practices are very important.

Mechanical

• Remove any sources that are irritating. Antibiotic ointment or drops is beneficial if there was significant damage that occurred. Good hand-washing practices must always be used

Medical Management

• Treatment is usually determined by the patient's cause of the injury and a thorough assessment for any corneal staining that is occurring. Then, the eye is placed in a patch.

Chemical-Induced Assessment

• In this step, the patient will first undergo continuous normal saline irrigation (NSIR). Cornea staining occurs and antibody therapy depends specifically on acute and chronic bacteria

Nursing Diagnoses of conjunctivitis

• Risk of infectious transmission: Inflammation of the conjunctiva • Pain: Related to inflammation of conjunctiva • Photophobia

Nursing Assessment

Assessments: • Monitor Vital Signs (VS): Body temperature alterations could possibly be linked to conjunctivitis.

• Teaching; emphasize the important of using routine hand hygiene • Stress how important it is to often wash the entire face

Hygiene

• Hygiene; it's important the nurse is advising the family to often change face towels. Encourage to isolate themselves
• Medication to achieve adherence, and then implement a close follow up
• The nurse is teaching patients that they must do anything and everything to prevent eye injuries or anything that could come close to the eye(s). • This includes applying protective measures
• Follow- up; the nurse encourages frequent follow up appointments
• *Conjunctivitis has 1 primary element to be aware of Patients need routine examinations and follow up appointments

Corneal Abrasion

• Common issue that patients go to emergency rooms, and the reason accounts to over 10% of eye related injuries.
• Contact lens wearers are most prone to abrasion • Types:
• Superficial
• Painful scratch
• Where epithelia cells are removed

Learn about visual acuity disorders, including refraction, refractive errors like myopia, hyperopia, and astigmatism. Understand how these conditions affect focus and vision clarity. Discover the causes and prevalence of these common eye problems.