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Cataracts

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The crystalline lens of the eye is clear and transparent. The lens focuses the light into the retina to create a sharp image, which helps people see objects clearly. In certain circumstances, the lens develops cloudiness or opacity. This obstructs light from being transmitted into the retina, causing blurring of vision. This condition is known as a cataract. Usually, cataracts do not cause any problems at an early stage as the cloudiness affects only a small part of the lens. But, as the cataract grows, they affect more parts of the lens, making it difficult for a patient to see objects. Both eyes usually get affected, but cataracts do not spread from one eye to another. A cataract might progress quicker in one eye than the other.

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Types

Cataracts can be classified into three types:


  • Cortical cataracts: This type of cataract leads to glare problems (increased sensitivity to sunlight or electric light) causing blurry vision while driving at night.

  • Posterior subcapsular cataracts: Younger people get this type of cataract, and the cataract progresses quickly.

  • Nuclear cataracts: In this type of cataract, a patient’s ability to see distant objects is affected. This condition develops slowly.

Symptoms

Some of the symptoms of a foreseeable cataract include:


  • Blurred vision

  • Faded colours

  • Difficulty in seeing at night

  • Changes in prescription in glasses

  • Double vision

  • Image distortion

  • Sensitivity to glare

  • The need to change glasses frequently


Vision loss due to a cataract is very gradual. The patient’s vision becomes cloudy, and colours become less clear with time. Patients face difficulty while driving at night. The degree of vision loss might differ in every patient. Poor vision also increases an individual’s risk of falling and hurting themselves.

Patients should consult an eye doctor as the above symptoms can also be signs of other eye problems. Sometimes, individuals with cataracts might suddenly see objects clearly without wearing glasses. However, this improved vision does not last for long.

Causes And Risk Factors

Causes

One of the most common causes of cataracts is advancing age which causes the lens to harden and turn cloudy. After 40, the proteins in the eyes break down, leading to the formation of clumps. These clumps create cloudy areas on the lens which gets more severe with age. In the age groups of 65 to 74, 20 out of 100 individuals have a cataract, and above the age of 74, 50 out of 100 individuals have a cataract. Other less common causes of the development of a cataract are:


  • Injuries

  • Infections

  • Radiation

  • Diabetes

  • In rare cases, children are born with the condition


Risk Factors

The main risk factor for a cataract is age. Other risk factors include:

  • Smoking

  • Too much alcohol consumption

  • Family history of cataracts

  • Too much exposure to sunlight

  • Steroid medications

  • Medications used for schizophrenia and bipolar disorder

  • Medications such as tranquillizers and diuretics

  • Nutritional deficiency

  • Poor living conditions

  • A baby could be born with cataracts if the mother had measles or rubella during pregnancy

  • Individuals living at high altitudes are at risk of developing cataracts

Prevention

Following preventive measures can be taken to protect your eyes from forming a cataract:


  • Wear sunglasses or a hat to block excess exposure to sunlight

  • Quit smoking

  • Include plenty of vegetables and fruits in your diet


Individuals of more than 60 years of age should get a yearly dilated-eye exam.

Diagnosis

Vision changes can also occur for other reasons; hence the eye doctor (ophthalmologist) first asks the patient for symptoms and family history. The doctor does an eye chart test to check the sharpness of vision at several distances. The eye doctor performs a dilated-eye exam to check for cataracts. In the dilated-eye exam, the doctor uses eye drops to dilate the pupil (black coloured centre of the eye) and then checks for cataracts or eye problems using a microscope. The pupils stay dilated for a few hours after a dilated-eye check-up. The sensitivity to light and glare increases with dilation, which makes it difficult for the eyes to focus. Hence patients are advised not to drive for a few hours.

Treatment

There is no scientifically proven medicine that can reduce or dissolve cataracts. Surgical removal is the only option.

One should consider surgery as soon as the cataract starts interfering with the patient’s lifestyle. You should ideally seek a seasoned ophthalmologist’s opinion before considering surgery.

There are several surgical techniques for cataract removal. The operating surgeon is the best person to decide which technique is likely to yield the best result. The types of surgeries are as below:


  • Intracapsular cataract surgery: The entire cataract is removed from the lens of the eye. This technique is now redundant and obsolete.

  • Extracapsular cataract surgery: The posterior capsule of the lens is not removed and is left behind to act as a support for intraocular lens implantation. Intracapsular and extracapsular surgeries  require a large incision and stitches which are removed after a short interval 

  • Phacoemulsification: This technique removes the cataract through a small 2 mm incision in the eye. The cataract in the lens is broken into fragments and each of these is then liquefied (emulsified) using ultrasound energy.  This technique usually takes 5-7 minutes, depending upon the density of the cataract Then,  foldable intraocular lenses (IOL) are inserted through these small incisions. Phacoemulsification is the most popular cataract surgery these days. It doesn’t require stitches, patches or injections.


The surgery takes very little time. Patients need to wear black or dark glasses for a day or two. These lenses are usually permanent and don’t need to be changed. They are of different types:

  • Mono-focal: Routinely used for most cases. They generally correct distance vision with a small number for near vision, such as reading, using a computer, etc.

  • Multifocal: These reduce the dependency on glasses for both distance and near vision. However, not all patients are suited for this type of lens and may need to discuss it with their doctors.

  • Toric IOL: These lenses are designed to reduce the high cylindrical number (astigmatism- a condition where the cornea or lens have different shape than normal leading to distorted vision).

  • Multifocal Toric IOL: This is recently available technology which corrects the cylindrical power and reduces the dependency on glasses for both distance and near vision.


After cataract surgery, patients may have itching, mild discomfort, watery eyes, an increase in light sensitivity, or blurry vision. The doctor generally advises to wear a patch until the follow-up or prescribe an eyedrop for healing. Sometimes, patients may develop an “after-cataract” after the surgery. This happens when a part of the natural lens is not taken out during the surgery leading to blurry or cloudy vision. This complication can be treated by a method called YAG laser capsulotomy. After-cataract may occur months or years after cataract surgery.

Lifestyle/management

In the early stages, the patient can make small changes to manage cataracts, such as using brighter lights at work, wearing anti-glare sunglasses, and using a magnifying lens for reading.

After cataract surgery, patients are advised to follow these instructions for a few weeks:


  • Wear dark sunglasses

  • Wash their hands while using eye drops

  • Prevent the entry of soap and water in the eye for the first few days post-surgery

  • Avoid touching the operated eye

  • Do not lift things that are heavy

  • Do not bend over

  • Avoid doing things that may result in an eye injury


The eye that has undergone surgery usually takes up to eight weeks to heal. However, an individual can restart some of their daily activities one day after the surgery. Patients are advised to use eye drops for a few weeks after surgery. The eye drops help a patient heal, prevent eye infection, and control pressure inside the eye.

Prognosis And Complications

Prognosis

Cataract surgeries have a very high success rate (over 99%). It is however important to realize that factors such as the condition of the retina and optic nerve, any pre-existing diseases and amblyopia (lazy eye) play a very important role in visual recovery after cataract surgery. Sometimes it may be difficult to diagnose any abnormality before the surgery because of the dense cataract.

In most cataract surgeries (including Phacoemulsification) the posterior part of the lens (the posterior capsule) is left behind. It is usually clear and forms a support for implantation of the intraocular lens. Since it is a part of the lens, it may become opaque and hamper vision even after cataract surgery. This condition is called posterior capsular opacification (colloquially known as ‘chari’). It may develop a few months or few years after surgery, though its incidence is significantly reduced with foldable lenses. Posterior capsule opacification can be treated by a short and painless procedure called as YAG laser capsulotomy.

Complications

If left untreated, a cataract usually worsens (becomes more cloudy). This leads to rapid deterioration of vision and erratic changes in eye glasses’ numbers. If a cataract is left untreated in the long run, it can cause glaucoma, intraocular inflammation and, in some conditions, the lens may even move from its original position. These complications may cause permanent damage that affects visual recovery even after surgery and may also make the surgery technically more difficult.

Precautions

After surgery for a cataract, a person can resume their normal lifestyle very soon. They can start reading after a day or two. While office work shouldn’t prove troublesome, they should avoid dusty environments or work that can cause physical strain. Patients should also avoid exercising and doing other sorts of workouts for four to six weeks. Swimming should be avoided for two months at least.

References

 


  1. Cataracts: overview. NCBI. Available at: https://www.ncbi.nlm.nih.gov/books/NBK390302/. Accessed on: March 11, 2021.

  2. Cataracts. University of Rochester Medical Center. Available at: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=85&ContentID=P00494. Accessed on: March 11, 2021.

  3. Cataracts. NIH. Available at: https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/cataracts. Accessed on: March 11, 2021.

  4. Cataracts. Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/8589-cataracts. Accessed on: March 11, 2021.

  5. Astigmatism. NIH. Available at: https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/astigmatism. Accessed on Mar 5, 2021.

  6. Cataract removal. MedlinePlus. Available at: https://medlineplus.gov/ency/article/002957.htm. Accessed on: March 11, 2021.

  7. Posterior Capsule Opacification. University of Michigan. Available at: http://www.med.umich.edu/1libr/Ophthalmology/Cornea/PosteriorCapusleOpacification.pdf. Accessed on Mar 5, 2021.


 

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