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Cataract
1. WHAT IS CATARACT?
A cataract is a dense, cloudy area that forms in the lens of the eye.
A cataract begins when proteins in the eye form clumps that prevent the
lens from sending clear images to the retina. The retina works by
converting the light that comes through the lens into signals. It sends
the signals to the optic nerve, which carries them to the brain.
It develops slowly and eventually interferes with your vision. You
might end up with cataracts in both eyes, but they usually don’t form at
the same time. Cataracts are common in older people. Over half of
people in the United States have cataracts or have undergone cataract
surgery by the time they’re 80 years old, according to the National Eye
Institute.
"Cataract" is derived from the Latin cataracta,meaning "waterfall"
SYMPTOMS OF CATARACT:
Common symptoms of cataracts include:
blurryvision
trouble seeingat night
seeing colours as faded
increasedsensitivityto glare
halos surroundinglights
double vision in the affected eye
a need for frequent changes in prescription glasses
2. CAUSES OF CATARACTS:
Age: lens proteins denature and degrade over time, and this
process is accelerated by diseases such as diabetes mellitus and
hypertension. There is loss of protective and restorative mechanism
due to alteration in gene expression and chemical processes within
the eye.
Trauma: blunt trauma causes swelling, thickening, and whitening
of the lens fibers. While the swelling normally resolves with time,
the white colour may remain.
Radiation: Ultraviolet light has been shown to cause cataracts, and
some evidence indicates sunglasses worn at an early age can slow
its development in later life. Microwave radiation has also been
found to cause cataracts.
Genetics: genetic component is strong in the development of
cataracts, most commonly through mechanisms that protect and
maintain the lens. The presence of cataracts in childhood or early
life can occasionallybe due to a particular syndrome.
Smoking and alcohol: Cigarette smoking has been shown to
double the rate of nuclear sclerotic cataracts and triple the rate of
posterior sub capsular cataracts.
Inadequate vitamin C: low vitamin C intake and serum levels have
been associatedwith greater cataractrates.
Medications: some medications, such as systemic, topical, or
inhaled corticosteroids may increase the risk of cataract
development.
Post-operative: nearly every person who undergoes
a vitrectomy—without ever having had cataract surgery—will
experience progression of nuclear sclerosis after the operation.
3. PATHOPHYSIOLOGY OF CATARACT:
The clear lens of the eye transmits light rays entering
the eye and focuses them on retina
With ageing lens proteins progressively denature causing
increase in density and yellowish-brown coloration of the
lens.
Other factors such as blunt force trauma can cause
thickeningand irreversible whiteningof the lens.
The resultant cloudy lens lacks the ability to
transmit and focus light rays on the retina.
This manifests as blurry vision or loss
of vision in advancedcases.
4. TYPES OF CATARACTS:
Nuclear cataracts form in the middle of the lens and cause the
nucleus,or the centre, to become yellow or brown.
Cortical cataracts are wedge-shaped and form around the edges
of the nucleus.
Posterior capsular cataracts form faster than the other two types
and affect the back of the lens.
Congenital cataracts, which are present at birth or form during a
baby’s first year, are less common than age-relatedcataracts.
5. Secondary cataracts are caused by disease or medications.
Diseases that are linked with the development of cataracts include
glaucoma and diabetes. The use of the steroid prednisone and
other medications can sometimes lead to cataracts.
Traumatic cataracts develop after an injury to the eye, but it can
take several years for this to happen.
Radiation cataracts can form after a person undergoes radiation
treatment for cancer.
6. RISK FACTORS OF CATARACT:
older age
heavy alcohol use
smoking
obesity
high blood pressure
previous eye injuries
a familyhistory of cataracts
too much sun exposure
diabetes
exposure to radiation fromX-rays and cancer treatments
DIAGNOSTIC STUDIES:
Your doctor will perform a comprehensive eye exam to check for
cataracts and to assess your vision. It includes:-
Visual acuity test – this eye chart test measures how well you see at
various distances.
Pupil dilatation – the pupil is widened with eye drops to allow your
eye doctor to see more of the lens and retina and look for other
eye problem.
Tonometry – standard test to measure fluid pressure inside the
eye.
The most common tonometry test uses a painless puff of air to
flatten your cornea and test your eye pressure. Your doctor will also put
drops in your eyes to make your pupils bigger. This makes it easier to
check the optic nerve and retina at the back of your eye for damage.
Other tests your doctor might perform include checking your
sensitivity to glare and your perception of colours.
7. TREATMENT FOR CATARACT:
If you’re unable or uninterested in surgery, your doctor may be
able to help you manage your symptoms. They may suggest stronger
eyeglasses,magnifying lenses, or sunglasses with an anti-glare coating.
Surgery: recommended when cataracts prevent you from going about
your daily activities, such as reading or driving. It’s also performed when
cataracts interfere with the treatment of other eye problems.
Phacoemulsification, most common method of removal. Phaco
involves a small incision on the side of the cornea. A tiny probe is
inserted which emits ultrasound waves that softens and break up
the cloudy centre of the lens so it can be removed with suction.
Extracapsular surgery involves removing the cloudy part of the lens
through a long incision in the cornea. After surgery, an artificial
intraocular lens is placed where the natural lens was.
Surgery to remove a cataract is generally very safe and has a high
success rate. Most people can go home the same day as their surgery.
8. Postoperative care
The postoperative recovery period (after removing the cataract) is
usually short. The patient is usually ambulatory on the day of surgery,
but is advised to move cautiously and avoid straining or heavy lifting for
about a month. The eye is usually patched on the day of surgery and use
of an eye shieldat night is often suggested for several days after surgery.
In all types of surgery, the cataractous lens is removed and
replaced with an artificial lens, known as an intraocular lens, which stays
in the eye permanently. Intraocular lenses are usually monofocal,
correcting for either distance or near vision. Multifocal lenses may be
implanted to improve near and distance vision simultaneously, but these
lenses may increase the chance of unsatisfactoryvision.
9. COMPLICATIONS OF CATARACT:
Rupture of the posterior capsule during surgery, which may result
in the nucleus dropping back into the vitreous cavity, necessitating
a further procedure (vitrectomy) either during the surgery or later.
Posterior capsule rupture may also result in the need to use a
differenttype of intraocular lens in the eye;
Raised intraocular pressure owing to the blockage of aqueous
humour outflow channels with the viscoelastic substance used at
surgery. Pressure may also rise as a reaction to the surgery or as a
result of inflammation. The patient is likely to experience pain and
new blurringof vision some hours after surgery;
A shallow anterior chamber, which may result from inhibition of
aqueous humour production because of a wound leak following
postoperative trauma, or from raised pressure. This is of concern,
because if the chamber becomes very shallow, the corneal
endothelium may touch the iris. Damage to corneal endothelial
cells may result in permanentcorneal oedema;
Retinal detachment may occur after cataract surgery in a very small
number of cases. Any report by the patient of new floaters in the
eye, flashing lights or the loss of sectors of vision indicates that an
urgent examination is required;
Cystoids macular oedema (oedema of the retina at the macular) is
likely to cause some disturbance of central vision. It often
disappears over time;
Uveitis (inflammation of the iris and ciliary body) occurs as an
inflammatory response to surgery. It is a normal consequence of
surgery and patients are treated postoperatively with eye drops
containing a steroid to reduce and control the inflammation. Pain
and redness of the eye may occur if the inflammation increases, in
which case modification of the drop therapyis required;
Displacement of the intraocular lens may occur after surgery and is
likely to necessitate further surgical intervention to replace the lens
or correctits position;
Posterior capsular opacification is the most frequent long-term
complication of surgery The posterior portion of the remaining lens
capsule becomes opacified and the patient reports reduction in
vision. Posterior capsular opacities are easily dealt with using a laser
to burn a hole in the capsule (YAG capsulotomy). This is painless,
and can easilybe undertaken as an outpatient procedure;
10. Infection is always a possible complication of surgery, and for this
reason a prophylactic antibiotic drop will be prescribed after
cataract extraction. The anti-inflammatory and the antibiotic may
be combinedin a single drop such as Maxitrol.
PREVENTION FOR CATARACT:
protect your eyes from UVB rays by wearingsunglasses outside
have regular eye exams
stop smoking
eat fruits and vegetables that contain antioxidants
maintain a healthy weight
keep diabetes and other medical conditions in check
11. NURSING ASSESSMENT:
Test papillary response.
Examine cornea to rule out any opacities.
Examine ocular adnexa.
Performdilated fundus examination.
PerformUSG B-scan.
Measure intraocular pressure.
Performpotential acuitymeasurement.
Performbiometry.
NURSING DIAGNOSIS:
Anxiety related to lack of knowledge –
Interventions - Assess the degree and duration of visual impairment.
Encourage conversation to find out the patient's concerns, feelings,
and the level of understanding.
Orient the patient to the new environment.
Explain the preoperative routines.
Encourage participation of family or the people who matter in
patient care.
Push to perform dailyliving habits when able.
Risk for injuryrelated to blurredvision –
Interventions - Help the patient when able to do until postoperative
ambulation and achieve stable vision and adequate coping skills,
using techniques of vision guidance.
Help the patient set the environment.
Orient the patient in the room.
Do not put pressure on the affectedeye trauma.
Use proper procedures when providingeye drugs.
Acute pain related to trauma to the incision andincreasedIOP –
Interventions - Assess the degree and duration of pain.
Encourage use of sunglasses in strong light.
Give cold compress on demand for blunt trauma.
Give medications to control pain and the IOP as prescribed.
12. ROLE OF NURSE IN CATARACT:
Although the care of patients with a cataract is a multidisciplinary effort,
nurses are increasingly undertaking much of the care surrounding the
surgical procedure.
Assessment is commonly carried out in preadmission clinics, with
ophthalmic nurses playing a lead role in the pre assessment of the
patient, including examining the eye, performing biometry, and obtaining
informed consent. Ophthalmic nurses also undertake a key role in
theatre, including the giving of sub-Tenon’s anaesthesia and acting as
first assistant to the ophthalmologist - a longstanding role within this
specialty.
Nurses undertake all postoperative care of patients who have had
uncomplicated cataract surgery and this may include the modification of
medication using patient group directives or supplementary prescribing,
auto refraction and final discharge of the patient from the service.
Tell the patient to avoid activities that increase intraocular pressure such
as straining.
Urge the patient to protect the eye from accidental injury at night by
wearing a plastic or metal shield with perforations, a shield or glasses
should be worn for protection duringthe day.
Advise the patient to watch for and immediately report complication
such as sharp pain in the eye that’s uncontrolled by analgesics this can
be caused hyphema (a clouding in the anterior chamber) and may herald
an infection.
13. RESEARCH:
N-Acetylcarnosine drops have been investigated as a medical treatment
for cataracts. The drops are believed to work by
reducing oxidation and glycation damage in the lens, particularly
reducing crystallin cross linking. Some benefit has been shown in small
manufacturer sponsored randomized controlled trials but further
independentcorroboration is still required.
Femtosecond laser mode-locking, used during cataract surgery, was
originally used to cut accurate and predictable flaps in LASIK surgery, and
has been introduced to cataract surgery. The incision at the junction of
the sclera and cornea and the hole in capsule during capsulorhexis,
traditionally made with a handheld blade, needle, and forceps, are
dependent on skill and experience of the surgeon. Sophisticated three-
dimensional images of the eyes can be used to guide lasers to make
these incisions. Nd:YAG laser can also then break up the cataract as in
phacoemulsification.
Stem cells have been used in a clinical trial for lens regeneration in twelve
children under the age of two with cataracts present at birth. The
children were followed for six months, so it is unknown what the long-
term results will be, and it is unknown if this procedure would work in
adults.
14. CONCLUSION:
Cataracts can interfere with daily activities and lead to blindness
when left untreated. Although some stop growing, they don’t get smaller
on their own. The surgical removal of cataracts is a very common
procedure and is highly effective roughly 90% of the time, according to
the National Eye Institute.
BIBLIOGRAPHY: