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MYOPIA or NEARSIGHTEDNESSA Refractive Error of the Eye

Overview (Pillitteri, Suddarth)

Refractive errors are the most common types of visual disorders. Normally light rays enter the eye via the cornea and pupil through the lens and falls directly on the retina. In refractive errors, vision is impaired because a shortened or elongated eyeball prevents light rays from focusing sharply on the retina. Blurred vision from refractive error can be corrected with eyeglasses or contact lenses.

The appropriate eyeglass or contact lens is determined by refraction. Ophthalmic refraction consists of placing various types of lenses in front of the patient’s eyes to determine which lens best improves the patient’s vision.

Types of Refractive Errors: MyopiaHyperopia

AnisometropiaAstigmatism

Definition

Myopia or nearsightedness or shortsightedness is a condition in which the eye over refracts or over bends the light causing images to be focused in front of the retina

Myopia is the ability to see objects clearly at close range but not a distance.

Classifications

Types of Myopia

1. Simple myopia – is more common than others and is characterized by an eye that is too long for its optical power

22. Axial myopia – caused because the eyeball is too long (from front to back – axial length) 3. Curvature myopia - is attributed to excessive, or increased, curvature of one or more of the refractive surfaces

of the eye, especially the cornea.4. Index myopia – caused because of increased strength of the refractive power of the eye (cornea, lens etc.) 5. Malignant myopia or degenerative myopia or progressive myopia or chronic myopia – is the type of

myopia that gets progressively worse overtime. 6. Pernicious myopia7. Prodromal myopia8. Stationary myopia9. Transient myopia

Incidence

1. One of the most common refractive disorders2. Congenital myopia, also known as infantile myopia, is present at birth and persists through infancy3. Degree of myopia develops with age as the person develops4. Youth onset myopia occurs in the early childhood or teenage, and the ocular power can keep varying until

the age of 21, before which any form of corrective surgery is usually not recommended by ophthalmic specialists around the world

5. Adult onset myopia Early adult onset myopia occurs between ages 20 and 40.[9]

Late adult onset myopia occurs after age 40.

Etiology

1. Genetic disposition to shortened or elongate eyeballs2. Medical causes:

a. Disease process – such as Glaucomab. Side effects from some drugs

Pathophysiology

1. The axial length of the eye is longer than the typical anatomical size of approximately 1”.

2. As light enters the eye and passes through the various structures – cornea, lens, pupil, aqueous humor – the elongated length causes the image to fall short of the retina.

3. As a result the child can only see objects that are closer to the eye, while those further from the eye appear fuzzy.

Clinical Manifestations/Signs & Symptoms

1. Blurred vision2. Dizziness, headaches3. Squinting when viewing objects greater than 2m away4. Rubs eyes excessively

35. Eyes tear up/excessive lacrimation (why excessive tearing)??6. Writes or colors with head close to table7. Must sit very close to watch the television8. Holds reading materials close to the face

User friendly notes: http://www.enurse-careplan.com/2010/10/nursing-care-plan-ncp-myopia.htmlThe symptoms of myopia often emerge during a child’s first years in school. Parents may notice that the child holds a book very close while reading or leans close to the desk surface while writing. He or she may squint a lot or sit very close to the television or blackboard. Other symptoms include headaches and failure to notice distant objects.

Diagnostic Evaluation

1. Indirect ophthalmoscope – allows the examiner to obtain a stereoscopic view of the retina Light source is from a head-mounted light Examiner views the retina through a convex lens held in front of the eye and a viewing device on the

head mount

2. Visual fields examination to determine the function of light pathways use a light source and a test subject – using Snellen Chart or the 6 cardinal fields of vision

3. Test refraction by instilling medication to with cycloplegic and mydriatic properties into the conjunctiva of the eye - which dilates the pupil

- Tropicamide (Mydriacyl) Cyclopentolate (Cyclogyl) - are two such medicines that cause ciliary muscles relaxation which causes the pupil to dilate (mydriasis) and lowered accommodative power (cycloplegia)

4. Electroretinography used to evaluate hereditary and disorders of the retina An electrode is placed over the eye to evaluate the electrical responses to the eye

User friendly notes: http://www.enurse-careplan.com/2010/10/nursing-care-plan-ncp-myopia.htmlMyopia and other refractive errors are evaluated by a series of vision tests. After the examiner takes a history of the patient’s symptoms (including a family history of eye problems), the patient is usually asked to read the letters on an eye chart known as a Snellen chart. Each eye is tested separately.

The examiner may also shine lights into the eyes or administer eye drops that allow him or her to see all the structures inside the eye clearly. This part of the examination allows the doctor to evaluate the severity of the patient’s nearsightedness. To measure the strength of the lens needed to correct the patient’s myopia, the examiner uses a device called a photopter (or refractor). The photopter is placed in front of the patient’s eyes and the examiner moves various lenses in and out of the device while the patient rereads the letters on the Snellen chart. The photopter can also be used to measure the correction needed for a bifocal lens.

Medical Management

1. Corrective lensa. Use concave lens or contacts which may need to be updated or changed periodically.

2. Refractive surgery – can reduce or eliminate dependency on glasses or contact lens. a. Excimer laser correction has been approved for adults since 1995

i. LASIK is the most commonly performed laser procedure. **Explain how this procedure works and the equipment used.

ii. A flap is made from some tissue in the cornea. A laser is used to remove some of the corneal tissue and the flap which was produced is now placed back in place. Basically tissue is

Must know that it’s a CONCAVE lens that is used to correct

4removed to allow more image to pass through the light. Correction of vision is usually excellent and stable over a period of time.

iii. Refractive surgery is currently not approved for pediatric patients age 1 – 15yrs.

b. Photo Refractive Keratotomy (PRK) - a layer of the cornea tissue is removed with a laser, which flattens the cornea and allows light rays to focus on the retina.

c. Orthokeratology - special contact lenses (retainers) must be worn that slowly reshapes the cornea to correct the myopia over a period of time. Depending on the person’s eyes these contact lens may only be worn at night. This procedure is not embraced widely in the eye care industry, b/c some doctors find that the effects are temporary.

d. Implantation – latest procedure for correcting early or mild myopia. Implantation of plastic corneal rings which also alters shape of cornea. One advantage is that they can be removed or adjusted.

User-friendly Notes: http://www.enurse-careplan.com/2010/10/nursing-care-plan-ncp-myopia.htmlVery mild myopia may not need corrective treatment. A person should see an eye doctor, however, if he or she is developing headaches or eye strain, or if blurry vision is interfering with daily activities. People whose nearsightedness is severe enough to require correction have several options:

1. Eyeglasses. These can be used to correct nearsightedness caused by uneven curvature of the lens or cornea as well as the length of the eyeball. Eyeglasses are prescribed by an optometrist or ophthalmologist but made and fitted by an optician.

2. Hard contact lenses. These usually provide more effective correction of nearsightedness than soft contact lenses.

3. Orthokeratology (Ortho-K). This is a procedure in which the person wears hard contact lenses for several hours overnight in order to gradually correct the curvature of the cornea. The lenses are removed during the day. Ortho-K is also referred to as corneal molding. It does not permanently improve vision. If the patient stops wearing the retainer lenses, his or her vision may return to its original condition. Ortho-K, however, is ineffective in correcting myopia caused by an abnormally long eyeball.

4. Laser Eye surgery . If a person’s nearsightedness is related to the shape of the cornea, an ophthalmologist can use lasers to reshape the cornea either by making a flap in the surface of the cornea and reshaping the tissue of the cornea under the flap, or by completely removing the upper layer of tissue in the cornea before reshaping the lower layers of tissue.

5. Lens implantation. Lens implantation is a controversial treatment for moderate or severe myopia. The ophthalmologist surgically inserts a clear corrective lens inside the eye in front of the natural lens. The procedure was not performed very frequently in the early 2000s, however, because it has a high risk of complications.

There are drawbacks to surgical correction of refractive errors. These include the risks of infection, development of haze in the cornea, or dry eyes. In some cases the surgeon may need to perform a second operation if the first one either overcorrected or under-corrected the shape of the patient’s cornea. It is important for a patient with myopia to discuss all the treatment options with the optometrist or ophthalmologist, as no two people have exactly the same degree of visual blurring or

5the same lifestyle. In addition, patients with diabetes require very careful evaluation before any type of laser eye surgery because diabetes weakens the retina of the eye and increases the risk of glaucoma.

Nursing Assessment

Person will present with report of blurred vision when looking at distant objects and clear vision when viewing objects that are near

1. Collect a history of the person (see notes from Assessment w/Sis. Joe-Brown)

2. Assess the patient’s mobility and self-care ability

3. Begin with visual acuity screening early in preschool years and whenever a child displays behaviors suggestive of acuity problems.

See above signs & symptoms

4. Check the vision of the client who has difficulty reading printing materials, identifying objects or following visual directions using a standard eye chart (e.g. Snellen)

5. Determine the types and amounts of support systems available to the patient ex (Is family near? Do friends visit regularly)

6. Review patients daily schedule

7. Refer clients for referral to the ophthalmologist or optometrist if vision is less than 20/30 or 20/40 in either or both eyes

8. Have clients view an eye chart while lenses of different strengths are placed in front of each eye. Ask whether lens sharpens or worsens the vision (Done by the Ophthalmologist)

Nursing Diagnosis, Interventions, and Expected Outcome

Nursing Dx: 1. Disturbed/Altered Sensory Perception (visual) r/t reduced vision aeb client’s blurry vision/inability to see

objects clearly

2. Risk for injury (falls) r/t reduced vision

3. Self-care deficit (hygiene, feeding, toileting) r/t reduced/altered vision aeb by poor appearance, inability to properly feed oneself, etc

4. Deficient Knowledge of postoperative expectations and continuing care r/t

Preoperative Interventions: 1. Assess the degree and duration of visual impairment and also the vision in the UNAFFECTED eye to be able

to have a comparison

2. Orient the client to the new environment (hospital room) – this increases client’s comfort and familiarity as well as builds confidence in the client/nurse relationship

3. When approaching client, approach on the unaffected side

4. Provide for the client’s safety – by ensuring all items needed are w/in reach, lower bed especially if depth perception is affected, ensure path to bathroom is free of obstructions.

65. Encourage clients to express feelings about visual impairment – helps to improve nurse-client confidence and

self-acceptance

6. Assess client’s understanding of surgical procedure clarifying info as needed

7. Reinforce teachings about post operation restrictionsa. Retching, vomiting, coughing, sneezing, should be avoided as much as possible – to prevent increased

intraocular pressureb. Client should avoid lifting anything other than 5 lbs c. Avoid straining when stooling

8. Remove all eye make-up, contact lens, and eye glasses and store in a safe place

9. Administer preparatory medications, drops, or ointments, as prescribed

10. Position bedside rails (up) after administering medications

11. Place the call bell next to the patient

12. Ensure informed consent is signed and dated by all persons.

Post Operative Nursing Interventions: 1. Transfer the client into the bed

2. Position the client as ordered (generally in semi-Fowler’s or Fowler’s position)

3. Put up bedside rails to protect the client from falling

4. Place the call bell next to the patient

5. Assess and document V/S, LOC, comfort, and status of eye dressing

6. Administer medications as prescribed – antibiotics, drops, anti-inflammatory drugs etc.

7. Maintain eye patch and shield as ordered

8. Report any sharp sudden eye pains to the physician

9. Inform the client when you are entering or leaving the room

10. Approach client on the unaffected side

11. Intervene as necessary to prevent vomiting, retching, sneezing

12. Instruct the patient to avoid bending over or straining which may cause an increase in IOP (Intraocular pressure)

13. Provide adequate diet and fluids to promote proper elimination and decreased straining during fecal elimination

14. Instruct the patient to avoid smoking, reading, and self-shaving for safety reasons

15. Instruct the patient to wear dark glasses if eyes are light-sensitive

16. Maintain a safe environment – doors should be completely closed and items should be cleared out of the patient’s walk-path.

17. Advise client to hold onto rails when going up and down stairs or in and out of bed

18. Emphasize the importance of proper handwashing and eye-care to prevent eye infections or corneal abrasions

19. Caution patient against rubbing eyes or wiping them w/soiled tissues

20. If contact lens have been prescribed:a. Teach client how to insert and remove themb. How to care for lens and the eyesc. Ensure client’s understanding by having them demonstrate these things

21. Teach client: a. How to instill eye drops and other meds as orderedb. How and when to apply eye patch or eye shieldc. Avoid rubbing or scratching, squeezing or touching the affected eyed. Avoid constipatione. Teach about activity limitationsf. Report to the Dr if the following symptoms occur

7i. Eye pain, increase eye pressure, redness, cloudiness, drainage, decreased vision, floaters,

halos around objects

Reducing Fear Recognized that dependence on sight is exaggerated when a person faces diminished vision or loss of

sight Recognize that each patient may manifest their concerns about the outcome of their surgery

differently – i.e – fear, depression, tension, resentment, anger, or rejection Encourage the patient to express his/her feelings Demonstrate interest, empathy, and understanding Reassure the patient that rehabilitative programs and personnel are available for assistance

Family Education and Health Maintenance – Discharge Planning

The prognosis of myopia depends partly on its severity. People with any degree of myopia can have their vision corrected satisfactorily by eyeglasses, contact lenses, or surgery. People with severe myopia (about 30 percent of nearsighted patients), however, have an increased risk of retinal disorders and glaucoma after age forty. They should therefore schedule regular eye examinations to reduce the risk of these complications.

Myopia is still largely considered a matter of heredity and cannot be prevented by any method known. There have been various attempts to slow the progression of nearsightedness in schoolchildren by eye exercises or such alternative therapies as biofeedback, but none have proved to be successful. People can, however, live comfortably with nearsightedness by visual screening in childhood, regular eye checkups at all ages, and wearing corrective lenses when needed.

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Medical Information on Myopia

What we see is made in the brain from signals given to it by the eyes.

What we see is in fact made in the brain. The brain makes sight from signals given to it by the eyes.

What is the normal structure of the eye?

The eye is made of three parts.

A light focussing bit at the front (cornea and lens). A light sensitive film at the back of the eye (retina). A large collection of communication wires to the brain (optic nerve).

A curved window called the cornea first focuses the light. The light then passes through a hole called the pupil. A circle of muscle called the iris surrounds the pupil. The iris is the coloured part of the eye. The light is then focused onto the back of the eye by a lens. Tiny light sensitive patches (photoreceptors) cover the back of the eye. These photoreceptors collect information about the visual world. The covering of photoreceptors at the back of the eye forms a thin film known as the retina. Each photoreceptor sends its signals down very fine wires to the brain. The wires joining each eye to the brain are called the optic nerves. The information then travels to many different special 'vision' parts of the brain. All the parts of the brain and eye need to be present and working for us to see normally.

What is Myopia?

Myopia is also known as 'short-sight'. This means that a child who is 'short-sighted' can see better at 'short' distance than 'long'. Often children with myopia can see clearly when reading a book but often find the television or the blackboard at school blurred.

Mild short-sight is a common and normal finding

Mild short-sight is a common and normal finding in about one in every twenty children. Every year for every one hundred children another one child will develop mild short-sight. By adulthood about one in four adults are short-sighted.

Why can objects at short distance be seen clearly but not at long distance?

A short-sighted (or myopic) eye cannot focus the light from an object at long distance sharply onto the retina at the back of the eye. Instead the light focuses to a sharp point in front of the retina. The vision is then blurred. If the object is brought nearer the eye, the point at which the light focuses sharply will move backwards onto the retina. An object at a short distance then becomes clear: the eye is 'short-sighted'.

Big eyes tend to be short-sighted

The bigger and longer and eye is the more likely light from a distant object will focus short of the retina. The focussing power of the cornea and lens are also important in causing myopia.

What is the cause of Myopia?

There are many reasons why a child might develop Myopia. Some of these include:

Their parents are short-sighted (myopic) and they 'inherit' Myopia The way they use their eyes may lead to Myopia They are born premature and with low birth weight They have an eye condition that is seen along with Myopia

9 They may have a condition of growth that causes their eyes to grow bigger than normal

If a child's parents are short-sighted the child is more likely to also be short-sighted

If a child has one parent who is short-sighted there is a one in three chance the child will also be short-sighted. If both parents are short-sighted then there is a one in two chance the child will be short-sighted. The child can be said to have 'inherited' the myopia.

Children who use their eyes lots for close work are more likely to become Myopic

There is some evidence that children who use their eyes more for looking at near objects, than other children, are more likely to become myopic. Children who are already myopic may increase their level of myopia. The reason why this occurs is not well understood.

Premature babies are more likely to become Myopic

Babies that are born earlier than usual and of lower birth weight have a one in two chance of becoming myopic. If they also develop a condition called Retinopathy of Prematurity then they are likely to become very short-sighted.

Some eye conditions can cause Myopia

For normal growth of the eye light needs to enter the eye without being blocked. If a child has a hazy cornea (corneal dystrophy) or lens (cataract) not all the light can enter the eye and the vision will be blurred. This may cause the eye to grow bigger and longer than usual. This leads to myopia. This is known as 'Form Deprivation Myopia'.

Some conditions of growth may cause Myopia

Some conditions of growth may cause Myopia. These conditions include:

Marfan's Syndrome Stickler's Syndrome Ehlers-Danlos Syndrome Homocystinuria

These conditions all tend to affect the way bones and joints grow. They also cause eyes to grow bigger than normal. This leads to myopia.

Myopia can often be seen along with other eye conditions

The bigger and longer an eye is the more likely it is to develop other eye conditions. These include:

Retinal Detachment Glaucoma Macular Degeneration Squint