What causes a cataract?
Cataracts is one of the most common eye conditions and they are a normal part of the ageing process. A cataract develops when the crystalline lens of the eye starts to discolour and harden as the protein structure within the lens deteriorates. They are common in people who are over the age of 60, however some people are born with hereditary cataracts. Other factors that can cause a cataract or accelerate its growth include:
- Excessive exposure to UV and other types of radiation
- Use of certain medications (e.g. Corticosteroids)
- Previous blunt/penetrating ocular trauma, surgery or disease
- Systemic disease (e.g. Diabetes and other metabolic disorders)
- Genetics and congenital disorders
What are the symptoms of a cataract?
Early cataracts may only affect the vision minimally, many patients are not even aware they have one until after an eye examination reveals so. As a cataract progresses to moderate and advanced stages, the following symptoms may arise:
- Cloudy vision
- Double vision in one eye
- A decline in far vision, near vision or both
- Increased sensitivity to bright light and glare
- Difficulty driving, reading and recognising faces
- Reduced contrast sensitivity
- Altered colour perception
- Reduced brightness/intensity of colour
If you notice any of these changes or symptoms of your vision please contact us at the Eye Specialist Institute and make an appointment today.
What are the different types of Cataracts?
The most common type of cataract is the nuclear sclerotic cataract and comprises of an overall clouding in the central part of the crystalline lens. This form of cataract progresses slowly and is often associated with ageing. Symptoms include cloudy vision.
Cortical Cataract causes spoke-like opacities to develop in the lens cortex. Symptoms can include increased glare sensitivity and difficulty reading and/or driving at night. People with diabetes are more susceptible to developing cortical cataracts.
Posterior Subcapsular involves a small opaque or cloudy area forming on the back of the crystalline lens. This form of cataract can develop quickly and symptoms can include blurry vision and increased sensitivity to glare. Posterior Subcapsular is occasionally associated with previous steroid use.
What complications can arise from Cataracts?
In certain cases, the growth of a cataract can make people more susceptible to primary angle-closure glaucoma. Primary angle-closure glaucoma occurs when the drainage canals in the eye get covered, and the angle between the iris and cornea are narrow due to the increasing size of the crystalline lens. This can develop rapidly and the drainage channel may become completely blocked, which will result in increased intraocular pressure. Your Ophthalmologist at the Eye Specialist Institute will be able to determine if you are at risk of developing primary angle-closure glaucoma and if it would be beneficial for you to undergo cataract extraction or any other treatments in order to prevent this severe condition from occurring.
How are cataracts diagnosed?
Your Eye Institute Specialist ophthalmologist will begin by measuring your visual acuity using a letter chart. Then a slit lamp microscope will be used to grade the cataract. Occasionally, dilating drops are required to enlarge the pupil and get a more detailed view of the back of the eye, this is to eliminate the possibility of any other eye diseases. These drops will blur your vision for 2-3 hours and we recommend that you do not drive on the day of your eye exam.
Optical Coherence Tomography (OCT)
Optical Coherence Tomography (OCT) allows for non-invasive imaging test which uses light waves to screen for any macular related diseases that could be impairing your vision. The Eye Specialist Institute recommends that an OCT always be performed before cataract surgery to fully evaluate the health of the eye as some macular problems may not be detectable in an eye examination alone, due to the density of the cataract.
How are Cataracts treated?
Surgery is the only effective treatment currently available to treat cataracts. The most common form of cataract surgery is Micro incision phacoemulsification cataract extraction and it involves removing the cloudy crystalline lens and replacing it with an artificial lens. The procedure is performed by your ophthalmologist under local anaesthetic and twilight sedation. A small (2-2.5mm) self-sealing incision is made on the side of the cornea and a fine ultrasound handpiece is used to emulsify the cataract - this process is called phacoemulsification. Following this, an Intraocular lens (IOL) implant, which has been specifically chosen for your eye, is inserted to replace the cloudy lens. In most cases, the IOL will naturally sit within the capsule that previously contained the crystalline lens and sutures will not be required to position it.
If you have cataracts in both eyes, the surgery to remove them will be performed on each eye at separate times, generally 4 to 8 weeks apart. Often people who require cataract surgery also have other underlying eye conditions present, such as glaucoma or Age-related macular degeneration. Please discuss with your ophthalmologist about how this will impact upon your cataract surgery.
How is the Intraocular Lens calculated?
The aim of an Intraocular lens (IOL) calculation is to provide the patient with a lens that fits the individual’s prescription. To achieve this, a series of scans are taken during your initial visit with The Eye Specialist Institute to measure the length of your eye and the curvature of the front of the eye. These values are then entered into a regression mathematical formula and an IOL strength is calculated according to your vision needs. IOL is a highly successful procedure, with a 90% chance of achieving the anticipated vision.
Your Eye Specialist Institute Ophthalmologist will talk you through your post-operative options and what you should expect after cataract surgery. These may include:
Distance Vision for Both Eyes
This is one of the most common results of cataract surgery with corrective glasses being required for intermediate and near vision.
This involves a mix of distance and intermediate vision. The dominant eye will be corrected for distance and the non-dominant eye for intermediate vision. The patient may still need to wear glasses for reading (particularly in dim lighting, with small font and/or reading for a long period of time) as well as night driving. Your ophthalmologist will trial you with contact lenses beforehand to ensure that you can adjust to the difference in vision between your eyes.
This involves a combination of distance and near vision. The patient’s dominant eye is treated for distance and the non-dominant eye is treated for near vision. Spectacles may also be required for intermediate vision. In comparison to cases of Blended Monovision, there is a significant difference in prescription between the two eyes and patients can take longer to adjust to Full Monovision.
Multifocal Intraocular Lenses
This form of implants are designed to provide patients with good distance and near vision in order to minimise or eliminate the need for glasses entirely. Multifocal IOLs can cause haloes around lights at night and spectacles may be required for long periods of intermediate vision e.g looking at a computer screen.
What happens if the desired IOL focus is not achieved?
There is an element of uncertainty when achieving the desired prescription following cataract surgery. Due to the IOL implant being calculated from a regression equation based on the results from 35,000 cataract surgeries there is a degree of variability in achieving your desired prescription.
In most cases, even if the focus does not turn out exactly as expected, it is more than likely going to be a considerably close match and your quality of vision should still be very good. Wearing glasses for certain activities such as reading or driving may be required to fix any discrepancies. In the situation where the postoperative prescription significantly differs from the planned result, your ophthalmologist may discuss with you the possibility of adjusting your vision. Treatment options available to do this include inserting a secondary IOL or performing laser refractive surgery.
What can I expect during and after cataract surgery?
Cataract surgery is a day theatre procedure and is considered to be a very safe operation, with 99% of cataract surgeries occurring with no complications. During the procedure, an anaesthetist will administer a local anaesthetic to ensure that your eye is numb and will provide sedation. After the surgery is complete you may experience mild grittiness and dry eye sensations, this is perfectly normal and can last from weeks to months at a time. If necessary, we can provide lubricating drops to alleviate these symptoms. One day after surgery your vision is expected to be good and will continue to improve during the first week. In 4-6 weeks reading glasses can be prescribed if needed.
In order to give your eyes the best recovery time possible, we strongly advise that during the first week you avoid getting any potential foreign matter in the eye and anything that could cause blunt force trauma. This also includes preventing any water from getting into the eye while bathing and showering. In regards to physical activity, exercise should be avoided for 2 weeks following surgery and swimming for 4 weeks.