What Causes Cataract?

Developing cataracts is often considered just a normal part of ageing. Although requiring cataract surgery is not necessarily inevitable, it is the most common eye procedure in the Western world for this reason. Whether you’re just curious, you know someone with cataracts, or you’ve been told you’re developing cataracts yourself, keep reading to learn about what causes cataract.

What is a Cataract?

Cataracts are an opacity or haze of the crystalline lens in the eye. Where the lens started as transparent in a healthy eye at birth, with time or due to other causes, it can begin to develop opacities or cloudiness. This can lead to the typical cataract symptoms, including:

• Blurry, hazy, foggy, or filmy vision
• Increased sensitivity to glare and bright lights
• More difficulty with seeing in low contrast environments, such as reading in dim lighting
• Altered colour perception
• Frequent changes to your spectacle or contact lens prescription

So, here’s some of what we know about what causes cataract.

Older age.

Cataracts are most common in those over the age of 50. There is a whole classification of cataracts attributed to increasing age, known as senile or age-related cataracts. It is thought that the accumulation of oxidative stress and damaging compounds within the body with age is responsible for developing cataracts. Free oxygen radicals and other molecules can damage DNA in the cells of the lens, as well as disrupt the careful arrangement of proteins and fibres. This results in the loss of transparency of the lens, which we then term a cataract. 

Genetics.

Genetic inheritance plays a role in many diseases, including those of the eye. The influence on genes comes from two directions. One is that some syndromes, which include an increased risk of cataracts, can be inherited or at least have some degree of genetic influence. These include myopia (short-sightedness), retinitis pigmentosa (a blinding eye condition), and Marfan’s syndrome. 

The other aspect of genetic predisposition to cataracts is the possibility of certain genes making one more susceptible to environmental causes of cataracts. This may explain why people with parents who developed cataracts at an early age may be at risk of also needing early cataract surgery. One study has noted that people who have a sibling with cataracts are three times more likely to grow cataracts too. 

Lifestyle choices.

Both cigarette smoking and alcohol consumption have been implicated in the development of cataract. As a side note, some research indicates that moderate alcohol consumption, which the study defined as 20g of alcohol per day, may actually help to reduce your risk of developing a cataract. 

Eye injuries.

Any disruption or damage to the fibres of the crystalline lens can cause a cataract. This can be from an electric shock to the body, or even from an eye operation unrelated to cataract surgery. Trauma to the eye may cause cataracts. This can include blunt injuries such as a cricket bat to the eye, or a penetrating injury, such as a sharp tree branch. A cataract can also be caused by ocular inflammation, such as a condition known as uveitis. 

Other medical conditions.

Certain systemic diseases have the potential to cause cataracts.

These include diabetes, which involves elevated glucose levels in the bloodstream. This can upset the balance of fluid content in the lens, resulting in what is often termed a “sugar cataract”.

Hypertension (high blood pressure), has been found to be associated with an increased risk of cataract too, as has obesity.

Though these are not often mentioned when discussing what causes cataract, managing these associated diseases well could possibly reduce cataract formation. 

Cataract Surgery

The only definitive way of treating a cataract is through cataract surgery. However, in the early stages of cataract development, you may be content to continue with your vision as it is. Many people are unaware of any changes to their vision when their cataracts are only mild. 

Slowly progressing cataracts can be managed by updating your glasses or contact lenses, and increasing the lighting around your home or office as needed. Once these solutions are no longer adequate to improve your sight to an adequate level, you may discuss them with your eye care professional about cataract surgery. 

In the majority of cases, understanding what causes your cataract is not relevant to your operation. However, you should still disclose all medical history to your ophthalmologist prior to cataract surgery. For example, cataract surgery is known to carry more risks of complications in people with diabetes, including swelling of the macula or exacerbation of diabetic retinopathy. 

Cataract surgery is a relatively straightforward day procedure. Prior to the operation, your pupils will be dilated with eyedrops and your eye area will be numbed with a local or topical anaesthetic. Though we don’t typically use general anaesthesia, you may be given a light sedative. Your ophthalmologist then creates a small incision in the front surface of the eye so that instruments can be inserted to break the cataract into fragments. These pieces are then suctioned from the eye, and an implant is inserted in the place of the hazy lens, allowing you to see clearly once more. 

If you suspect you’re developing a cataract, speak to your eye care professional about whether cataract surgery is indicated at this point in time. 

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

References

Age-Related or Senile Cataract: Pathology, Mechanism, and Management. 

https://austinpublishinggroup.com/clinical-ophthalmology/fulltext/ajco-v3-id1067.php

Genetic Origins of Cataract. 

some degree of genetic influence

Cataract Surgery and Its Complications in Diabetic Patients.

https://www.tandfonline.com/doi/abs/10.3109/08820538.2014.959197?journalCode=isio20