Cataract

In a normal eye, light enters through the cornea and passes through a clear lens which helps to focus the images onto the retina (the light sensitive screen at the back of the eye). These images are converted in the retina into electrical signals which are transmitted to the brain by the optic nerve allowing us to ‘see’. A clear lens allows full passage of light into the eye

1) What is a cataract?

Any clouding or loss of clarity of the lens is called a cataract. This may initially interfere very little with vision. However the cloudiness generally increases over a period of time until the light is blocked from entering the eye and vision is completely impaired. Although cataracts usually affect both eyes, they can progress at different rates in the two eyes. The presence of cataract in one’s eye is not hazardous to the health of the eye unless the cataract becomes completely opaque and white in colour. When this happens, it is called a “mature” cataract. A cataract that has become “mature” causes blindness and can cause inflammation in the eye with pain and headache. A “mature” cataract requires early surgical removal.

2) Why does a cataract develop?

Most often cataract occurs in older people as part of the ageing process. In infants, a cataract may be caused by infection, chemical imbalance, or developmental abnormality. The tendency to develop cataract may also be inherited. Eye injury, prolonged ultraviolet light exposure, diabetes, high blood pressure, smoking, consumption of alcohol, malnutrition, certain ocular diseases as well as certain medications such as steroids may contribute to the development of cataract.

3) Symptoms of cataract

Most patients may experience one or more of the following symptoms:

• Increasing haziness resulting in blurred or distorted vision
• A gradual loss of colour vision - objects appear yellowed
• Worsening of vision in dim light and an increasing need for more light to see clearly
• Glare at night resulting in haloes or coloured rings around bright lights
• A tendency to lose distance vision because of the increasing density of the lens
• Double vision
• Need for frequent change of glasses.

4) How is a cataract treated?

Nonsurgical cataract treatment

There is no proven medication that can prevent a cataract formation or cause a cataract to clear. When a cataract is mild, a change of glasses may be helpful. In all other situations, surgery is the only treatment available.

Cataract Surgery

Cataract surgery consists of removing the cloudy natural lens (the cataract). In most cases, the cloudy lens is replaced with a lens implant or intraocular lens (IOL).

5) When should one have cataract surgery?

Cataract surgery is recommended if it is interfering with normal work or daily activities. With modern methods of surgery, cataracts no longer need to reach full maturity in order to be removed. If the cataract is creating (or is likely to create) other serious complications inside the eye, it will require surgery. Sometimes it can block the doctor’s view of the retina and even prevent effective diagnosis and treatment of serious retinal diseases. In these situations a cataract surgery is recommended so that the retinal disorder can be treated effectively.

6) Types of cataract surgery

Currently two most frequently used techniques to remove a cataract are:

• Extracapsular Cataract Extraction (ECCE)
• Phacoemulsification (PKE)

In both the above surgeries an intraocular lens (IOL) implant is placed within the eye for optimum vision.

7) Anaesthesia

Most cataract surgeries are performed under local anaesthesia. Local anaesthesia has a pain - killing effect (analgesia) & also keeps the eye still during surgery (akinesia). However the patient remains conscious during the surgery. General anaesthesia is sometimes preferred in children, mentally handicapped patients and others who are likely to prove uncooperative during surgery. Phacoemulsification is now performed using topical anaesthesia in the form of anaesthetic eye drops. While this produces analgesia, akinesia does not occur. A high level of patient cooperation is therefore required.

8) ECCE

In ECCE, an opening is made (8-10 mm wide) and the hard nucleus of the cataract is removed as a single piece. The capsule of the natural lens is used as a support for an IOL. At the end stitches are applied to close the opening made in the eye.

9) Phacoemulsification (PKE)

Phacoemulsification is the latest, most sophisticated method of removing a cataract. A very small opening (3-4 mm) is made in the eye and using a special probe with an ultrasonic tip, the hard nucleus is broken into small pieces which are then sucked out of the eye. IOL is then implanted within the capsular bag. The opening into the eye seals by itself without the need for stitches. Most patients will be able to see fairly well without glasses very soon after surgery.

Phacoemulsification has many advantages over ECCE surgery:

Because the opening made in the eye is very small there is more safety not only while performing the surgery but even in the post -operative period.

Since sutures are not required, there is little or no induced astigmatism leading to early visual recovery and greater stability of vision.

Period of rest after PKE is only 10-14 days compared to the 6 week rest following ECCE surgery.

10) What is an IOL?

Intraocular lens (IOL) is made of plastic or silicone and remains permanently inside the eye. It provides the best optical substitute for the natural lens. Thin glasses may still need to be worn at times for distance viewing and almost always for near vision since the artificial lens does not have the capability to change its focusing capacity. Posterior Chamber (PC) IOLs are placed using the capsule of the lens as a support for the lens. Newer foldable PC IOLs can be folded for implantation through a small incision. Once a foldable lens has been placed in the capsular bag, it unfolds to its full normal size. Thus the incision can remain 3-4 mm. Some IOLs are designed to be positioned in front of the iris which acts as their support. These are called Anterior Chamber (or AC) IOLs and are usually implanted in rare cases of ECCE or PKE if a PC IOL cannot be implanted.

11) How safe is cataract surgery?

Cataract surgery is one of the most successful and rewarding eye surgeries. However, since it is an operation, some complications can develop and must be considered before surgery. These include: Infection: Since the eye is opened for this surgery, a serious internal infection (endophthalmitis) could develop and permanently harm or even destroy the eye and vision. This can generally be controlled by medications. Sometimes additional surgery is required so that the eye is not completely lost. The risk of infection is however low (about 3 to 5 for 1,000). Hemorrhage: In certain abnormal conditions, some eyes may bleed internally resulting in an unusual surgical complication. If the bleeding cannot be controlled by the surgeon by any means, vision can be damaged or lost, but the chances of this happening are very remote (about 1 in 10,000). Retinal Detachment: Cataract surgery causes a slight disturbance to the internal dynamics of the eye and vitreous gel movement occasionally causes one or more small tears to form in the retina. The patient may then experience sparks or flashes of light and black spots interfering with his vision. If not given medical attention, these tears can progress to a retinal detachment and loss of vision. Most retinal tears can be sealed with a laser or a freezing with cryo probe. Even if detachments occur, they can be treated effectively with surgery. Cystoid Macular Edema (CME): In this condition a swelling of the central area of the retina called the macula can occur. Patients may then experience some blurring and distortion of images. This condition occurs rarely and may recover completely. Double vision: A temporary double vision can occasionally occur due to the effect of the anesthetic on the delicate muscles that control the coordinated movement of the eye. If double vision becomes a problem, further surgery can usually reduce or reverse the condition. After Cataract: This misleading term does not mean a return of cataract after surgery. What actually happens is that the transparent posterior capsular support of the IOL becomes translucent and thus does not allow complete transmission of light. The patient’s vision once again becomes slightly hazy as if a cataract is developing again. This can be easily remedied by laser treatment in the out-patient department itself. The laser is able to create a small opening in the posterior capsule. Light once again passes unimpeded through the small opening and vision is restored.

12) What is “laser” cataract surgery? What is “no injection, no stitch, no pad” cataract surgery?

In PKE an ultrasonic probe is used to fragment the hard nucleus so that it can be sucked out of the eye through a small opening. A laser can be employed for the same purpose. However, laser removal of cataract is still in the experimental stage. Cataract surgery is advertised in some centers as a “no injection, nostitch, no pad” procedure. Patients can walk in, have the surgery and return home after a few hours. The term “no injection” means that no local anesthesia is given. Instead the eye is rendered free of pain by the topical application of anesthesia as eye drops just before surgery. Because the entry into the eye is specially constructed to be self-sealing the opening does not need sutures. This is the meaning of the term “no stitch”. Because the anaesthesia is topical, a bandage is not applied over the eye. Hence, the term “no pad”. We however prefer to apply a bandage over the operated eye for 24 hours after surgery. Not applying a bandage over the eye after surgery is not prudent especially in our country where crowds and pollution pose a risk of infection entering into the operated eye and possible permanent loss of sight.

13) What happens when a patient with cataract comes to Karna Eye Clinic?

All patients with cataract undergo a detailed eye examination which may take one hour. If surgery is decided upon, further scanning tests called DBR will be performed to calculate the power of the IOL which will provide the best vision. A physician’s examination and basic laboratory investigations are then performed to assess fitness to undergo surgery under anesthesia. This usually takes 1-2 days. Day care or ambulatory surgery means that the patient gets admitted on the day of the surgery and returns home a few hours after surgery on the same day itself. Post-operative examinations are scheduled 3-4 days after the surgery.