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CATARACT AND CHOICE OF LENS

cataract is an opacification of the lens of the eye which leads to a decrease in vision.

 Cataracts often develop slowly and can affect one or both eyes.

 Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces.

Cataracts are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, longstanding use of corticosteroid medication, smoking tobacco, prolonged exposure to sunlight, and alcohol.

Treatment : Surgical 

The appropriateness of surgery depends on a person's particular functional and visual needs and other risk factors.[

Cataract removal can be performed at any stage and no longer requires ripening of the lens. Surgery is usually "outpatient" and usually performed using local anesthesia

Phacoemulsification is the most widely used cataract surgery in the developed world.This procedure uses ultrasonic energy to emulsify the cataract lens. Phacoemulsification typically comprises six steps:

  • Anesthetic – The eye is numbed with either a subtenon injection around the eye (retrobulbar/peribulber  block) or topical anesthetic eye drops. The former provides paralysis of the eye muscles.

  • Corneal incision – Two cuts are made at the margin of the clear cornea to allow insertion of instruments into the eye.

  • Capsulorhexis – A needle or small pair of forceps is used to create a circular hole in the capsule in which the lens sits.

Phacoemulsification – A handheld ultrasonic probe is used to break up and emulsify the lens into liquid using the energy of ultrasound waves. The resulting 'emulsion' is sucked away.

  • Irrigation and aspiration – The cortex, which is the soft outer layer of the cataract, is aspirated or sucked away. Fluid removed is continually replaced with a saline solution to prevent collapse of the structure of the anterior chamber (the front part of the eye).

  • Lens insertion – A plastic, foldable lens is inserted into the capsular bag that formerly contained the natural lens. Some surgeons also inject an antibiotic into the eye to reduce the risk of infection. The final step is to inject salt water into the corneal wounds to cause the area to swell and seal the incision

Intraocular lens (IOL) is a lens implanted in the eye as part of a treatment for cataracts or myopia. The most common type of IOL is the pseudophakic IOL              

                              TYPES OF IOL { intarocular lens }

  • Monofocal 

 Monofocal IOLs are standard lenses used in cataract surgery. One of the major disadvantages of these conventional IOLs is that they can only be focused for one particular distance - either optical infinity (rendering the eye emmetropic) or a fixed finite distance (rendering the eye myopic).

  • Multifocal : 

Multifocal IOLs attempt to provide simultaneous viewing of distance vision and near vision,  Trifocal IOLs can provide intermediate vision

  • Accommodating :

Lens designs attempt to allow the eye to regain some partial focusing ability in order to change focus from distance to near 

  • Toric : 

A toric IOL is a type of toric lens used to correct preexisting corneal astigmatism at the time of cataract surgery.toric IOLs have different powers in different meridians of the lens, and they must be positioned on the correct meridian to reverse the preexisting astigmatism. If the toric IOL is not on the correct meridian, it may need to be repositioned in a second procedure.

  • Multifocal toric : 

Standard toric IOLs are monofocal, permanently focused on distant objects. Multifocal toric IOLs are also available. These lenses provide the patient not only with correction of preexisting astigmatism, but also with multiple-focused vision at far and reading distance

To know more on the types of lenses available and suitable for your eye please consult doctor

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