Cataracts are one of the most common causes of reversible blindness in the world, with around 10 million cataract operations performed globally each year.
The natural lens in your eye becomes cloudy or opaque, causing scattering of light and diminished rays entering the eye. This makes it harder to see clearly, causing visual morbidity.
Many types of cataracts exist, including nuclear sclerotic, cortical and posterior subcapsular.
Nuclear Sclerotic Cataracts
Nuclear sclerotic cataracts are the type that we usually associate with age. Approximately 25% of people develop these cataracts by the age of 75.
Symptoms that might occur include:
- Blurry, unfocused or unclear vision
- Colour contrast may change might look different,
- Glare, particularly for night driving
This type of cataract tends to have an insidious progression over years.
Conceptualise the natural lens as a peanut M&M. Beyond the outer hard shell, is the inner chocolate (which is equivalent of the lens cortex in this comparison). Cortical cataracts occur when this area becomes more opaque and can be directly due to the affects of Father time.
Under the microscope, cortical cataracts are characterised by white streaks or wedge-shaped opacities (called cortical spokes) which grow on inwards toward the middle of your eye. This leads to symptoms such as:
- Problems with light glare
- Contrast and depth perception
The exact impact on vision is dependent on exactly where the lens opacity is found.
Posterior Subcapsular Cataracts
As the name suggests, posterior subcapsular cataracts form on the back of your lens, beneath the lens capsule (the outer coloured shell of the peanut M&M).
Symptoms can include increasing difficulty reading and difficulty seeing in low illumination. Conversely to nuclear sclerotic and cortical, this type is more commonly seen in younger age and can develop due to other systemic causes. This is especially true for those taking high doses of corticosteroids and diabetic patients.
To summarise, cataracts can be considered an inevitable part of living and surgery likely to be required by us all. Timings of corrective cataract surgery depends on:
- Other pathologies
- Patient’s choice
This blog is contributed by Gurjeet Jutley.