Sunday-November 19, 2017 
    
      Home | Procedures | Pre-Surgery Form | Registration | Search | About Us  
 
FORBES magazine names YourSurgery.Com as one of it's "Best of the Web"
 
Cataract Removal
Removal for improving vision

Humans are blessed with eyes that allow excellent colored as well as black and white vision which act as a camera for the brain. Quite often when an individual ages, the lens of the eye can become cloudy impairing vision. Surgery for removal of the cloudy lens corrects this problem and restores vision to normal. Approximately 1.2 million cataract surgeries are performed annually in the United States.

Anatomy and Physiology

  • There are two eyes that lie in bony casings within the skull called orbits
  • Each eye is globular in shape and about one inch in diameter
  • Light entering the front of the eye passes through the cornea, anterior chamber, iris, lens and vitreous and finally is focused on the retina, the film of the eye. (Figure 1)
  • The cornea is a curved, highly transparent tissue that separates air from clear fluid in the anterior chamber of the eye, which lies between the cornea and lens
  • The lens is a firm gel-like transparent tissue that is almost eight millimeters (one-third inch) in diameter and biconvex in shape, that is, thicker in the center than at the edge. A thin transparent capsule surrounds the lens.
  • In front of the lens is the iris, a circular pigmented muscle that gives the eye its color. It has a hole in its center, the pupil. The iris acts like the diaphragm of a camera and adjusts the amount of light that enters the eye through the pupil
  • Light then passes through the vitreous, a clear gel-like material that fills the center of the eye, onto the retina
  • The retina is the film of the eye. It is a true extension of the brain and is composed of special nerve cells sensitive to light
  • The optic nerve is formed from these nerve cells and carries the light image entering the eye to the brain
  • Light entering the eye is focused at two places, the cornea and the lens. Light is primarily bent as it passes the cornea and then fine focused as it passes through the lens

Figure 1 - Eye Normal

Pathology

  • With aging, the lens of the eye becomes clouded due to a chemical change in the composition of the lens
  • While this may occur early in life, it generally occurs after the age of 45 (Figure 2)
  • Some of the causes are:
    1. Hereditary defect
    2. Ultraviolet radiation from the sun
    3. Injury to the eye
    4. Diabetes
    5. Infection
    6. Certain medications such as steroids
  • Cataract prevention takes the form of
    1. Protecting the eye from injury
    2. Control of diabetes
    3. Wear sunglasses that screen out ultraviolet radiation. Whenever you go outside in bright sun whether it be on the beach or on the slopes skiing, it is very important that sunglasses are worn that filter out almost all of the harmful ultraviolet rays
Figure 2 - Clouding of lens produces a cataract.

History and Exam

  • Vision becomes progressively more clouded and distorted as a cataract develops. One eye may become clouded more rapidly than the other such that the individual notices dimmer vision and distortion in one eye and not the other
  • Color may become less distinct and the eye may become more sensitive to light and glare
  • There may be frequent changes in the prescription of eyeglasses and when very cloudy a change in prescription may no longer help
  • The normally black pupil of the eye may appear white or yellow
  • When the cataract develops slowly, the cataract may not be noticed until vision is significantly worse

Tests

  • The diagnosis of a cataract is made by eye examination by an ophthalmologist (eye doctor), using special instruments such as an ophthalmoscope (a hand held series of lens and light source) or slit lamp (an office instrument with a controlled light source)
  • Other tests that measure night vision, contrast sensitivity and color vision may be used in making the diagnosis

Indications

  • Some cataracts may remain small or limited to the outer margin of the lens and not require surgery. Surgery is considered only when the cataract significantly effects vision
  • For individuals who depend on their eyes for everyday activities such as work, may need treatment earlier than others

Cataract Surgery

  • There are three procedures for removal of a lens with a cataract. Each is carried out under the operating microscope by the ophthalmic surgeon. The procedures are usually carried out under local anesthesia though a general anesthetic may be used in selected cases (Figure 3)
  • Phacoemulsification
    1. A small incision is made just outside the cornea
    2. A tiny instrument that emits ultrasonic vibrations is inserted through the incision into the lens
    3. The vibrations break up the cataract into fine fragments that can be gently removed from the capsule by suction
    4. The back of the capsule remains intact
    5. A few sutures close the incision
  • Extracapsular extraction
    1. The lens is removed in one piece through the incision
    2. The back of the capsule remains in place
    3. The small incision is closed with a few sutures
  • Intracapsular extraction
    1. In this procedure, the entire cataract lens and the surrounding capsule is removed
    2. Frequently a freezing device is used to remove the cataract
  • After the cataract is removed, one of three procedures may be used to restore the function of the lens. (Figure 4)
    1. Cataract lens. These are strong, thick glasses that increase the size of objects. There are drawbacks such as distortion when looking off-center, objects seem larger than before, straight lines appear curved and side vision is limited
    2. Contact lens. While contact lens do not have the drawbacks of cataract lens, it is necessary to remove and insert the lens sometimes on a daily basis
    3. Intraocular lens. This is a small plastic lens that is inserted in the eye after the cataract has been removed
      • With one type of lens the ophthalmic surgeon enlarges the initial incision and the plastic lens is slipped behind the iris and up against the back wall of the capsule. This is the position of the normal lens. Occasionally the intraocular lens may be inserted in front of he iris
      • Another uses a folded flexible plastic lens roughly one-fourth inch in diameter. The folded lens is inserted into position behind the iris using a small instrument called an injector. When the injector is removed, the lens opens into position
Figure 3 - The cataract is removed
Figure 4 - The intraocular lens is inserted between the posterior capsule and iris

Complications

  • Complications specific to cataract surgery range from minor to the complete loss of the eye
  • Sometimes a complication may occur months or years later
  • The capsule may become clouded at a later time. This is known as a secondary cataract and may occur in 30-40 percent of patients. This, however, can be corrected by making an opening in the clouded capsule using a pulsed YAG (yttrium-aluminum-garnet) laser (Figure 5)
Figure 5 - A clouded posterior capsule is opened using the YAG laser
  • Dislocation of the implanted lens
  • Infection
  • Hemorrhage into the anterior chamber or vitreous
  • Clouding of the cornea
  • Separation of the retina from the back of the eye with loss of vision
  • Glaucoma may develop
  • Double vision may occur
  • Atrophy of the iris with inability to change the size of the pupil
  • Droopy eyelid
  • The necessity the lens to be removed or repositioned
  • Uveitis, a non-infectious inflammation of the pigmented portions of the eye such as the iris that can result in visual loss

Postoperative Care

  • This surgery lasts under one hour
  • After surgery the patient is taken to a recovery area
  • The eye is bandaged and protected with a metal shield

After Care

  • Most activities can be resumed almost immediately, however, heavy lifting and strenuous exercise should be avoided for the first week
  • The first office visit is usually within the next 48 hours
  • Vision usually improves within a few days, but healing continues for eight to twelve weeks during which time vision continues to improve