What Is Cataract?

The human eye consists of various layers with  various functions. The most important part of the eye  is the eye lens and it can be affected by cataract. 

The eye lens is a  transparent, biconvex disk located behind the iris and pupil. Which bends  light and focuses it onto the retina to help you see things clearly.

Cataract is the  cloudiness of the lens that results in a scattering of light that decreases the light reaching the retina resulting in vision loss and blindness.. There are many different types of cataracts and the common causes include:

• Ageing  (cortical cataract, nuclear cataract and posterior subcapsular cataract which can either occur isolated or in a mixed form)
• Existing comorbidities 
• Genetics (congenital cataract)
• Other environmental factors

Read on to learn more about cataracts including the causes, signs & symptoms, management & treatment and preventative measures that you can take to reduce your risk of developing a cataract.  

Overview

Cataract is an eye disease and a major cause of vision problems in older people  however it is treatable. Cataracts mainly affect the eye lens, which  focuses and bends light to help you see. There are various forms of cataracts and are classified based on the location of where the cataract has formed.

Cortical cataract

Cortical cataract is mainly seen in diabetic patients. The cataract  forms at the cortex of the lens and progresses towards the centre of the lens. Cortical cataract is associated with astigmatism i.e. when the cornea or lens is curved more steeply in one direction than the other.¹ 

Radiation cataract

Frequent exposure to UV-B radiation can result in cortical cataract.

Nuclear sclerotic cataract 

Nuclear cataract is the most frequent type of age related cataract. Normally the eye lens is composed of epithelial cells that undergo repeated turnover with the arrival of new cells. These new epithelial cells get converted into lens fibres. As you age this process happens less efficiently leading to a build up of damaged cells and proteins. These damaged cells and proteins move towards the centre or nucleus of the lens initiating nuclear cataract formation. 

Posterior subcapsular cataract  

The cataract that develops behind the lens.

Each of the mentioned cataracts above can either occur isolated or in a  mixed form e.g. cortical and nuclear cataract. 

Congenital cataract

Can occur during birth or within a year of life and is the major cause of blindness and impaired vision in children. They can be due to some genetic conditions such as autosomal-dominant congenital cataract, galactosemia and Lowe syndrome. Some of these cataracts are too small to have an impact on children's vision.² 

Secondary cataract 

After cataract removal there are chances of developing scar tissue which creates a cloudy lens.

With the advent of newer technologies and diagnostic measures cataract can  be diagnosed at an early stage and surgical removal of cataract is only required in cases where the eye health is deteriorating drastically.

Causes of cataract

Apart from age and congenital causes, other risk factors include: 

Diabetes- There are various mechanisms involved in cataract development in diabetic patients.  The biggest reason being, in diabetic patients there is a high amount of glucose within the circulation  which gets synthesised into a sugar called sorbitol.  Sorbitol then causes cell shrinkage, oxidative stress and  cataract formation.³

• Any kind of trauma or serious injury to the eye
• Smoking and alcohol consumption
• Patients who have had  glaucoma eye surgery 
• Patients who take steroids

Signs and symptoms of cataract

The cataract symptoms differ between various  types but a few common cataract symptoms include:

• Blurry vision
• Double vision
• Glare and halos from lights
• Common daily tasks such as reading or driving gets difficult
• Bright light seems to be too striking
• Inability to appreciate colour and contrast sensitivity

Management and treatment for cataract

When a patient experiences  cataract symptoms the optician will do the following  :

• They  would primarily look for vision problems by making patients read a Snellen chart and near card. 
• Look through the  patient's  medical history for any medical conditions, genetic disorders,  trauma or eye problems
• Check the movement of the eye muscle
• Dilate the pupil of the patient using eye drops and examine with the aid of an ophthalmoscope  to identify the extent of cataract formation
• Using a slit lamp to find the location of where the cataract was formed on the lens and the specific type of cataract the patient has 
• Witnessing a red reflex back after observing through ophthalmoscope  in a normal condition⁴

Initial stages of cataract could be managed by: 

• Wearing anti glare glasses 
• Using bright lights at home 
• Using  magnifying glasses for reading and other activities

When the vision loss is too severe, eye surgery is advised to the cataract patients.

Prior to cataract extraction other things are checked such as:

• A complete evaluation of eye power 
• Examining the presence of any eye conditions such as pupillary defect
• Neovascularization of the iris  
• Assessing the health of the cornea 
• Checking the ocular pressure or eye pressure via a dilated fundoscopy, tonometry or  gonioscopy

Sometimes a higher diagnostic tool such as an  optical coherence tomography (OCT), B Scan ultrasonography, and fluorescein angiography may be required for serious eye conditions. 

Cataract surgery has developed gradually with the advent of newer technologies from extracapsular or intracapsular cataract surgery to phacoemulsification. Cataract surgery involves the surgical removal of clouded lens and is replaced by an artificial lens called intraocular lens. .

Phacoemulsification is when  a small incision is made into the lens capsule and the cloudy lens is blended or emulsified with a tool and aspirated. After which an intraocular lens is placed into the capsule bag, reducing the post operative risks associated with cataract surgery.  

Risks associated with cataract surgery are: 

• Secondary cataract - is the development of scar tissue behind the lens capsule and artificial lens
• Swelling, inflammation and bleeding
• Changes in eye pressure
• Retinal detachment

Preventive measures

Steps that can be taken to reduce the risk of developing a cataract include:

• Abstaining from drinking alcohol and smoking
• A diet consisting of fruits and vegetables rich in vitamin A,C,E may prevent cataract formation⁵
• Avoiding the risk factors such as exposure to UV light, managing diabetes, and intake of steroids ⁶

FAQs

How can I prevent cataracts?

Avoiding  certain risk factors, including plenty of antioxidants in your diet and consulting an optician   periodically if you are a diabetic patient or on steroids for other conditions

Who is  at risk of cataract?

Factors that can increase the risk of cataract formation are:

• Chronic smoking
• Drinking excessive amounts of alcohol
• Diabetic
• A family history of cataract  
• Exposure to UV radiation 
• Any kind of injury or eye surgery 

How common is cataract?

94 million people around the world face blindness or refractory problem due to cataract as per a 2018 WHO report.

When should I see a doctor?

When you experience  some of the symptoms like blurry vision, cloudiness, diminishing vision, double vision and glare you should consult an optician. 

Summary

Cataract is a common eye condition displaying features of blurry and cloudiness on the eye lens which impacts the  eye health and ultimately leads to vision loss.  A slit lamp and other diagnostic approaches are used by the optician to diagnose the patient.

Age related cataract is the most common type of cataract and is normally seen in patients around  45-50 years. It includes cortical cataract, nuclear cataract and posterior subcapsular cataract which can occur by itself or in a mixed form.

Other types of cataracts include congenital cataract, radiation cataract and secondary cataract.

Some of the known causes of developing a cataract include diabetes and other comorbidities such as age, , smoking and alcohol consumption, trauma and UV radiation. Taking care of these risk factors may prevent development of a cataract. 

Cataracts  can be treated by managing the symptoms although for major cases cataract removal by replacing  the natural lens with artificial lens is the most popular  treatment optionIf not treated it can result in glaucoma, inflammation and other major eye problems