Causes of Cataracts and Why They're so Common
Published: 05 September 2021
Published: 05 September 2021
Did you know that cataracts are responsible for half of the world’s blindness (Fred Hollows Foundation 2015)?
The human eye is made up of several components used to receive and transmit visual information (Perkins 2020). The lens, which sits behind the iris, plays an important role in focusing light on the retina, a light-sensitive membrane at the back of the eye. The light that hits the retina is turned into electrical signals that are transmitted through the optic nerve to the brain (NEI 2019a; Mayo Clinic 2018).
The lens in a healthy eye should be clear, allowing the retina to receive a clear, sharp image (Mayo Clinic 2018). A cataract is when the lens becomes cloudy, causing vision impairment (Vision Australia 2017).
Cataracts are primarily age-related. In fact, almost every person who is 80 or older has some level of cataract formation (Better Health Channel 2014).
Despite this, it is possible, albeit less common, for people to develop cataracts at a young age, or even be born with them (Vision Australia 2017).
Cataracts may be unilateral (affecting one eye) or bilateral (affecting both eyes) (Healthdirect 2019).
While cataracts are a leading cause of blindness, most people can be successfully treated and regain their vision (Healthdirect 2019).
The lenses in the eyes generally become less flexible, thicker and less transparent with age or certain conditions, breaking down their protein structure and forming clumps. These clumps cloud areas of the lens, creating cataracts. The clouding gradually expands and becomes denser (Mayo Clinic 2018; NEI 2019b).
In Australia, cataract is the second most common cause of bilateral vision impairment and cataract surgery is the most common elective surgical procedure (ACSQHC 2017).
Cataracts are a significant issue for First Nations peoples, being 12 times more likely to affect First Nations peoples than non-First Nations Australians. Furthermore, First Nations peoples wait about 63% longer than non-First Nations Australians to receive cataract surgery (Vision 2020 Australia 2019).
Cataracts can be categorised depending on their location within the lens:
(Vision Eye Institute 2017; Turner 2020; Mayo Clinic 2018)
Congenital cataracts may be related to genetics, intrauterine infection, trauma or conditions such as rubella (Mayo Clinic 2018).
In addition to age, other risk factors include:
(Vision Australia 2017; Healthdirect 2019)
Someone with cataracts may experience:
(Vision Australia n.d.; Healthdirect 2019; Mayo Clinic 2018)
Symptoms may not be noticeable until the cataract has progressed to a more advanced stage (Vision Australia 2017).
Cataracts can be identified through an eye examination, where a practitioner will assess vision, the appearance of the eye and the retina. The pupils may need to be dilated using eye drops so that the retina can be examined. A slit lamp may be used to magnify the eye so that the location and pattern of the cataract can be determined (Healthdirect 2019; Mayo Clinic 2018).
Other tests such as a CT scan, MRI scan or ultrasound may be used to examine the back of the eye (Healthdirect 2019).
Glasses and visual aids such as magnification and lighting modifications may improve vision in the early stages of a cataract, but these are not permanent solutions. Once the cataract progresses, surgical treatment is the only effective long-term option (Vision Australia 2017; Healthdirect 2019).
Cataract surgery is one of the most commonly performed and successful surgical procedures (Vision Australia n.d.). It is straightforward and performed in about 20 minutes, generally only requiring local anesthetic (Fred Hollows Foundation 2015; Healthdirect 2019).
The procedure involves removing the clouded lens and replacing it with a new, artificial one (Healthdirect 2019).
Replacing the affected lens with an artificial one may not only restore vision, but also correct any refractive errors (such as myopia). As a result, some patients may no longer require glasses after the procedure (ACSQHC 2017).
The risk of cataracts may be reduced by:
(Vision 2020 Australia 2018)
In 2021, the Australia Commission on Safety and Quality in Health Care released the Cataract Clinical Care Standard. This standard aims to guide the assessment and care of patients over the age of 18 with cataracts in all healthcare settings (ACSQHC 2021a).
The standard comprises the following eight quality statements:
|Quality Statement 1: Primary care assessment and referral||Patients with suspected cataracts undergo an initial assessment for:
|Quality Statement 2: Patient information and shared decision-making||Patients are provided information in a form that is appropriate for them to support shared decision-making. They are given the opportunity to discuss their needs and preferences, as well as the potential benefits and consequences of their options.|
|Quality Statement 3: Access to ophthalmology assessment||Patients who have been referred for surgery consideration are prioritised for ophthalmology assessment based on their clinical needs.|
|Quality Statement 4: Indications for cataract surgery||Patients are offered surgery when their cataracts are at a stage where:
|Quality Statement 5: Prioritisation for cataract surgery||Patients are prioritised for surgery based on:
|Quality Statement 6: Second-eye surgery||When a patient with bilateral cataracts is planning surgery for their first eye, the practitioner should discuss with the patient whether the second eye will be operated on, and if so, when the second procedure will take place.|
|Quality Statement 7: Preventive eye medicines||Patients should receive an intracameral antibiotic injection at the time of surgery. Postoperatively, they receive anti-inflammatory eye drops only if indicated.|
|Quality Statement 8: Postoperative care||Patients should receive appropriate postoperative care until they have recovered to ensure any complications are addressed.|
Question 1 of 3
What type of cataracts are characterised by fissures that resemble the spokes of a wheel?
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