Grey hairs, wrinkles, and nuclear sclerosis. A few things are inevitable with increasing age. Although the likelihood of developing a nuclear sclerotic cataract isn’t necessarily considered absolutely certain, the vast majority of older Australians will experience some degree of cataract, with more than 70% of those aged over 80 years old having cataract in one or both eyes.
What is Nuclear Sclerosis?
A nuclear sclerotic cataract is one of three types of age-related cataract, the other two being cortical cataract and posterior subcapsular cataract. In general, the term ‘cataract’ refers to any sort of opacity within the crystalline lens of the eye. Age is not the only cause of cataract; factors such as trauma, disease, and medications can also induce a cataract in the eye.
Nuclear sclerotic cataracts form within the centre of the lens, known as the nucleus. It appears as a yellowish-brown discolouration of this portion of the normally clear and transparent structure, and will typically become a denser brown as the nuclear sclerosis progresses with time.
Nuclear sclerotic cataracts are thought to be due to the nucleus of the lens becoming compacted and hardened with age, as outer lens fibres are continually being formed and laid around the nucleus. This affects the transparency of the lens, and although total vision loss is unlikely, an advanced cataract can impair the vision until treatment is provided.
What are the Symptoms of Nuclear Sclerosis?
Because any opacity within the crystalline lens of the eye naturally impedes the passage of light through this structure, vision is often affected in some way. In the very early stages of a nuclear sclerotic cataract, a patient may not notice any changes to their vision, especially as these changes tend to happen very slowly over time.
As the cataract progresses, a patient may notice:
- A filmy sensation to the vision; patients may describe this as like looking through a dirty window
- Decreased contrast sensitivity; this can affect a patient’s ability to read print and they may find they are more reliant on bright lighting compared to previously. Driving in low visibility conditions such as heavy rain may also become more difficult
- Alterations to colour vision; this is due to the yellowing of the lens from a nuclear sclerotic cataract, which will filter out certain wavelengths of the colour spectrum
- Blurry vision; that may be worse for reading before it becomes noticeable at distance vision.
An interesting phenomenon associated with nuclear sclerosis is termed the ‘second sight’. Due to structural changes of the lens, patients with nuclear sclerosis often experience what eyecare professionals call a ‘myopic shift’, which refers to a prescription becoming more short-sighted due to changes to the refractive index of the ageing lens. Depending on the starting prescription, some patients may find their vision for certain distances actually improves with the development of nuclear sclerosis. However, this is not a permanent change and as the nuclear sclerosis progresses further vision will begin to deteriorate across all distances.
Treatment of Nuclear Sclerotic Cataract
Up to a certain point, deteriorating vision from a nuclear sclerotic cataract may be improved by simply updating the prescription in glasses or contact lenses. However, eventually, an untreated cataract becomes so dense and opaque that it blocks sufficient light entering the eye to form any sort of useful vision and the patient may require surgery to restore the sight.
As cataracts do not cause permanent vision loss but cataract surgery is associated with a very low risk of complication, most practitioners will advise patients to wait until the cataract impedes the vision required for their daily activities before undergoing surgery.
Cataract surgery is a very common procedure in Australia, performed by an ophthalmologist, and is known to have very good rates of success. Under topical anaesthesia, a small incision is made in the cornea, which is the clear dome of tissue at the front of the eye. This allows access for instruments to get to the cataract and fragment it into smaller pieces for extraction through the corneal incision. An implant calculated to the desired final prescription is then inserted into the capsule where the cataract once was.
Typically, no stitches are required as the incision is small and designed to be self-sealing, however, the patient will be given a protective shield to wear over the eye and post-operative eye drops to use for the following month or so. Once the eye has healed, the patient may be advised to return to their optometrist for an updated prescription as the surgery would likely have altered this. Many patients are no longer as dependent on glasses or contact lenses after this procedure.