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Cataract – Phacoemulsification, Aftercare

A cataract is a clouding or opacity of the lens that leads to gradual painless blurring of vision and eventual loss of sight. Worldwide cataract is the primary cause of reduced vision and blindness.

EPIDEMIOLOGY

Age-related cataract is responsible for 48% of world blindness, which represents about 18 million people, according to the World Health Organization. In many countries surgical services are inadequate, and cataracts remain the leading cause of blindness. As populations age, the number of people with cataracts is growing. Cataracts are also an important cause of low vision in both developed and developing countries. A person with a normal life span is more likely to undergo a cataract operation than any other major surgical operation.

CLASSIFICATION OF CATARACT

The most common cataract is the age related or senile type. Senile cataracts usually begin around the age of 50 yrs & by 80 yrs of age, about 85%of persons have some clouding of the lens.

They are of 3 types:

1)    SUBCAPSULAR

2)    NUCLEAR

3)    CORTICAL

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Cataract Classification

1)    Subcapsular: These cataracts may be anterior or posterior.

i)     Anterior:   Anterior type lies directly under the lens capsule and is associated with fibrous metaplasia of the anterior epithelium of the lens.

ii)   Posterior: Posterior type lies just in front of the posterior capsule and is associated with posterior migration of the epithelial cells of the lens.

2)    Nuclear: This cataract is an exaggeration of the normal ageing change involving the lens nucleus.

3)    Cortical: This cataract is one in which the opacification involves the anterior, posterior, or equatorial cortex. The opacities frequently assume a radial spoke-like or shield-like configuration, and eventually the entire cortex becomes opacified.

ETIOLOGY

Cataracts may develop as a result of many other systemic, ocular and congenital disorders.

Systemic Disorders include Diabetes, Tetany, Myotonic Dystrophy, Neurodermatitis, Galactosemia, Lowe’s syndrome, Werner’s Syndrome and down syndrome.

Intraocular Disorders include iridocyclitis, retinitis, retinal detachment and onchocerciasis.

Congenital Disorders: Infections like German measles, Mumps, Hepatitis, Polio mylitis, Chicken pox, Infectious mononucleosis during the first trimester of pregnancy may cause congenital cataract.

Blunt trauma, Lacerations, Foreign bodies, Radiation, exposure to infra-red light and chronic use of corticosteroids may also result in cataracts.

RISK FACTORS

The cumulative exposure to ultra-violet light over a person’s life span is the single most important risk factor in cataract development. People who live at high altitudes or who work in bright sunlight, such as, commercial fishermen, appear to experience cataract formation earlier in life. Glassblowers and welders who do not wear eye-protection are also at higher risk.

PATHOPHYSIOLOGY

1)                       Any injury i.e. Etiological factors or risk factors leading to Reduction in oxygen uptake and initial increase in water content in lens resulting in Dehydration of the lens. So, Sodium and calcium contents are increased: Potassium, ascorbic acid, and protein contents are decreased.

2)    The protein in the lens undergoes numerous age-related changes, including yellowing from formation of fluorescent compounds and molecular changes.

3)    These changes along with the photoabsorption of ultra-violet radiation throughout life result in cataract formation by a photo-chemical process.

Cataract progress in a predictable pattern. They begin as immature cataracts that are not completely opaque and some light is transmitted through them, allowing useful vision. Mature cataracts are completely opaque. Vision is significantly reduced. Hypermature cataracts are those in which the lens proteins break down into short chain polypeptides that leak out through the lens capsule. The pieces of protein are engulfed by macrophages, which may obstruct the trabecular meshwork, causing phacolytic glaucoma.

CLINICAL MANIFESTATIONS

  • Blurred vision
  • Monocular diplopia (double vision)
  • Photophobia (light sensitivity)
  • Glare because the opacity of the lens obstructs the reception of light and images by the retina.
  • Better vision in low or dim light because pupil is dilated and allows for vision around central opacity.
  • Painless
  • Cloudy lens can be observed.
  • Halo around lights especially street lights at night.

DIAGNOSIS

  • Physical examination: On physical examination, it can be observed directly.
  • Ophthalmoscope examination: A cataract should be suspected when the red reflex seen with the direct ophthalmoscope is distorted or absent. Although cataracts can usually be easily identified with the direct ophthalmoscope, an accurate determination of the type and extent of the lens change requires a slit-lamp examination.

MANAGEMENT

There is no known treatment other than surgery that prevents or reduces cataract formation.

SURGICAL MANAGEMENT

Cataract surgery is painless and is performed on an outpatient basis. Cataracts are usually removed under local anaesthesia.

Extracapsular Cataract Extraction (ECCE): In this method, only the anterior portion of the lens capsule plus the capsule contents are removed and intraocular lens (IOL) is placed.

Intracapsular Cataract Extraction (ICCE): Cataracts can also be removed within their capsule. In this method, a freezing (cryo) probe that adheres to the surface of lens is used to extract the cataract.

Modern cataract surgery technique has changed significantly over the last 30 years from ICCE to ECCE with IOL in the late 1970s, to small incision phacoemulsification during the late 1980s, followed by the adoption of sutureless phacoemulsification with foldable IOL in the 1990s.

Sutureless Phacoemulsification: The cataract is removed by making the small incision in the cornea. The cataract is broken into microscopic particles using an ultrasonic probe. The use of high energy sound waves is called phacoemulsification. Then a folded intraocular lens (IOL) is inserted through the micro-incision, then unfolded and locked into permanent position. The small incision is self-sealing and usually requires no stitches. It remains tightly closed by the natural outward pressure within the eye. This type of incision heals fast and provides a much more comfortable recovery.

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Sutureless Phacoemulsification

PREOPERATIVE CARE

Preparation of the eye includes instillation of eyedrops, such as a mydriatic/cycloplegic and a local anesthetic on the day of surgery. A tranquilizer or mild sedative may also be prescribed. If topical anesthetic is given, eye should be protected by an eye-pad or glasses.

INTRAOPERATIVE CARE

Most eye surgery is now being performed as ambulatory surgery except when complications are present preoperatively. Local anesthesia is used for most of the procedures in adults. As the pupil is widely dilated during surgery, the patient can see only the light but not the surgeon’s actions. The patient’s head is positioned so as to avoid movement during surgery.

POSTOPERATIVE CARE

The goals of postoperative care are to prevent:

1)    Increased intraocular pressure.

2)    Stress on the suture line.

3)    Hemorrhage into the anterior chamber.

4)    Infection.

When intraocular pressure (IOP) is increased, pressure is placed on the suture line and bleeding may occur. Anterior flexion of the head not only increases IOP but also may cause anterior synechia (adhesion of the iris to the cornea) because of decreased fluid in the anterior chamber and inflammation from the trauma of surgery. Thus activities that increase IOP such as straining and leaning over, are contraindicated after surgery because a sudden increase in pressure places stress on the suture line. Protection of the eye with eye-shield or glasses prevents injury. Infection is prevented by the correct use of eyedrops and eye pads, topical antibiotics may be given prophylactically.

Special instructions regarding activities to avoid, eyedrops to be instilled and symptoms to be reported are provided to the patient.

Care after cataract removal

1)      Leave the eye patch in place.

2)      For 24 hours, limit your activity to sitting in a chair, resting in bed, and walking to the bathroom.

3)      Do not rub your eye.

4)      You can wear your glasses.

5)      Do not lift more than 5 pounds (the weight of a gallon of milk).

6)      Do not strain (or bear down).

7)      Do not sleep on the operative side of your body.

8)      Take your eyedrops.

9)      Take acetaminophen (e.g., Tylenol) as needed for pain or itching.

10)Do not take aspirin or drugs containing aspirin.

11)Report any pain that is unrelieved, redness around the eye, nausea and vomiting.

12)Wear an eye shield to protect your eye.

COMPLICATIONS

Postoperative infection, bleeding, macular edema and wound leaks are possible. However, side-effects after cataract surgery are rare. But the incidence of retinal detachment is higher in the first 12 months after cataract surgery. Other complications are dropped nucleus , wound dehiscence, pseudophakic corneal edema, IOL dislocation, and postoperative endophthalmitis.