Test- Ch. 25-26 Flashcards
Hyperopia
If the distance between the lens and retina is too short, the light rays focus behind the retina.
This causes difficulty in seeing objects close at hand and is called farsightedness (hyperopia).
Myopia
If the opposite is true and the eyeball is too elongated, the light rays will converge and focus in front of the retina.
The individual then has difficulty seeing objects at a distance and is referred to as being nearsighted. Nearsightedness is called myopia.
Accommodation
accomplished by ciliary muscles and ligaments that change the shape of the lens, making it more rounded or flatter, thereby allowing light rays to fall on the retina.
Presbyopia
With increasing age, the ciliary muscles become less elastic and cannot readily accommodate the needs of distant and near vision.
Hardening of the ciliary muscles occurs in many people older than 40 years and is known as presbyopia.
Bifocal eyeglasses are usually prescribed for this condition because they allow for two sets of lenses in one pair of eyeglasses, one for viewing distant objects and one for seeing close objects.
Astigmatism
a visual defect that results from warped lens or an irregular curvature of the cornea.
What does astigmatism prevent?
The horizontal and vertical rays from focusing at the same point on the retina.
What happens when there is a serious error of refraction?
The eye will tire easily or the person will have defective vision because the eye cannot change the shape of the lens enough to compensate for the abnormality
What is the treatment for astigmatism?
Treated with prescription eyeglasses or contact lenses that are fitted so that the light rays are brought into proper focus on the retina.
Refractive surgery permits the correction of refraction problems for some people.
Nearsighted (myopic) can undergo one of three procedures: PRK, Lasik, or Smile.
What is Photorefractive Keratectomy (PRK)
An excimer laser is used to remove a thin layer of tissue from the cornea that corrects the excessive curvature of the cornea that is interfering with the proper focus of light rays through the lens.
Takes 30 minutes and start to see improvement within 3 to 5 days.
What is Laser-Assisted in Situ Keratomileusis (LASIK)
Used to treat nearsightedness
The Middle layer of the cornea is reshaped with a laser after a very thin outer layer of the cornea is peeled back.
The outer layer is replaced.
Takes 10 to 15 minutes per eye and is performed as an outpatient procedure.
What is small incision lenticule Extraction (Smile)
A laser procedure in which the cornea is reshaped by the excision of a small piece of corneal tissue, correcting myopia.
What is Uveitis?
The uveal tract consists of the iris, the ciliary body, and the choroid. Uveitis is the inflammation of the uveal tract.
What are the causes of Uveitis?
Herpes virus
Syphilis
Cytomegalovirus
Toxoplasmosis
Tuberculosis
West Nile virus
S/s of Uveitis
Tearing
Blurred vision
Photophobia
Aching around the eye
A bloodshot sclera
A small, nonreactive, irregular pupil
Treatment of Uveitis
Involves resting the ciliary body with a cycloplegic drug.
The pupil is dilated to prevent adhesions of the involved structures.
Analgesics, antibiotics, and oral or ocular steroid therapy may be used.
Cool or warm compresses are used for discomfort.
Sunglasses should be worn to reduce photophobia.
Low light indoors is advisable.
What is dry eye?
a common condition in people over 40 years old, especially in women after menopause. Because our population of older adults is growing, the incidence of dry eye is increasing.
What is dry eye?
a common condition in people over 40 years old, especially in women after menopause. Because our population of older adults is growing, the incidence of dry eye is increasing.
What causes dry eye?
1.) a deficiency of tears, such as seen in Sjögren syndrome
2.) evaporation, resulting from a dysfunction of meibomian glands that can be exacerbated by environmental conditions such as dust and wind (Foster, 2019
S/S of dry eye
Tearing
Soreness
A gritty feeling in the eye.
Treatment of dry eye
Symptoms can be treated with lubricating eye drops, but if the condition is left untreated, it may lead to corneal ulcers.
Dry eye is managed by treating the underlying cause, such as meibomian gland dysfunction, and keeping the tear layer of the eye moist and functional.
Patients with insufficient tears should use a solution of artificial tears that is readily available over the counter.
Prescription eye drops and ointments are available for those conditions that do not respond to standard artificial tears (Shtein, 2020).
What is Keratitis?
An inflammation of the cornea caused by irritation or infection
Causes of keratitis?
People who have had strokes, comatose patients, people with exophthalmos (protruding eyeballs), and bacterial infections
Treatment for Keratitis
Treatment of irritation is instillation of artificial tears.
Infection is treated by a medication to kill the organism.
Drugs may be given topically, subconjunctivally, or by intravenous (IV) infusion.
Causes of corneal ulcers
A corneal ulcer may occur from irritation, infection, or injury.
The ulcer is cultured to determine whether there is a causative organism when there is no history of injury.
Antibiotic medication is usually prescribed.
Scarring from corneal ulcers or severe infection is treated by keratoplasty.
Corneal transplants replace corneas that have been damaged by:
Genetic disorders
Trauma
Ulcers
Diseases such as keratitis (inflammation of the cornea)
What are the two types of Corneal transplantations?
Full-thickness keratoplasty
-Corneal transplant
-Restores vision in approximately 95% of patients
- Corneas are retrieved from donor cadavers soon after death
-Performed with regional ansesthesia
Lamellar Keratoplasty/Descemet stripping endothelial keratoplasty (DSEK)
-Replaces only a superficial layer of corneal tissue
-Used only when disease is limited to the endothelial surface
-Currently, the preferred treatment
-Lining is replaced through a tiny incision
-No sutures
-Cells are held in place for the first 24 hours by an air bubble
-Vision is improved in a matter of weeks
Patient education for Corneal Transplantation
The patient must understand that it is difficult to predict when a donor cornea will become available, and therefore the procedure may be set up on short notice.
Preoperative Care for Corneal Transplant
The surgery is an outpatient procedure.
As part of the preoperative preparation, the surgeon clearly marks the operative site, verifying verbally with the patient that the site is correct. The nurse should document that this was done in the medical record and that all present agreed.
The patient must understand beforehand that it takes 1 to 2 weeks before any improvement in vision is noticeable and that improvement will continue for several months.
Preoperative care is much the same as for other eye surgeries.
Postoperative Care for Corneal Transplant
Prevention of infection is extremely important.
After surgery, the patient is observed for 1 to 2 hours and then is discharged home.
For some procedures a pressure dressing and eye shield may be applied in the surgical suite after the procedure and should be removed only by the health care provider the next day.
The shield is then worn at night and when around small children or pets for at least a month.
The pressure dressing helps keep the donor tissue in contact with the eyeball.
Nursing actions focus on caring for the patient’s disturbed visual sensory perception.
Instructions regarding safety are provided before discharge.
The patient may lie only on their back and nonoperative side postoperatively.
Postoperatively, an older adult patient may experience a loss of independence and a change in self-perception.
Will need specific suggestions on ways to maintain independence
Will need someone to help at home for a few days at least
Graft rejection is a possibility and is heralded by inflammation beginning near the graft edges.
This finding must be reported promptly.
Should the first transplant fail, the procedure can be redone.
Because the cornea does not have an abundant blood supply, healing is very slow and is not complete for about 1 year.
What are common causes of eye trauma?
Accidents and debris in the air
Not using safety googles or glasses
Windy weather blowing stuff into the eye
Penetrating injuries to the eye
Being struck in the eye by an object that does not penetrate, such as abaseball, can cause injury
How to remove shallow foreign body from the eye?
If the foreign body is not deeply embedded in the tissues of the eye, it can easily be removed by irrigation.
Irrigation with clear, lukewarm water (at home) or sterile water or saline is used to remove a foreign body sticking to the cornea.
Continuous irrigation can be done with small tubing, and a bottle of solution or an irrigating syringe can be used.
Be very careful not to touch the eye with the tip of the irrigating device.
Sometimes a speck of foreign matter on the cornea can be removed with a moistened, sterile cotton swab.
Have the patient tilt the head back.
Hold the eyelids open to prevent blinking
How to remove a foreign body sticking out of the eye?
If a foreign body is sticking out of the eye, no attempt to remove it should be made.
Both eyes should be patched to prevent further eye movement, and the patient should be transported to the emergency department (ED) or to an ophthalmologist.
Corneal Abrasion:
When they are complaining of a sensation that a foreign body is in the eye after it appears to have been removed by irrigation, or complains of continuous pain, refer them to a health care provider immediately because there may be a corneal abrasion
How to test for Corneal abrasion?
The provider will apply a stain to assess whether the cornea is abraded.
Treatment for Corneal abrasion
The medicated ointment will be prescribed, and the eye may be patched.
Patient education on Corneal abrasion
A thin line of eye ointment is applied from the inner canthus to the outer canthus along the lower eyelid inside the conjunctival sac.
The patient closes the eyelid and moves the eyeball around in the socket to distribute the ointment.
Excess medication is gently wiped away with a tissue, moving from the inner canthus to the outer canthus.
If an eye patch is not applied, the patient is warned that the ointment may blur vision for a while.
A corneal abrasion is painful; a nonsteroidal anti-inflammatory drug may be used for discomfort.
How to apply a pressure patch
Use two eye patches. Fold the first one in half, place it over the closed lid, and then place the other patch on top of the folded one. Apply tape as instructed previously.
