Cataract Assessment & Treatment
CATARACTS
They eye acts like a camera, and the lens inside the camera focuses the light on the film or retina in the back of the eye. When the crystalline lens inside the eye loses transparency this is called a cataract.
Cataracts can affect the vision in a number of ways depending on the location of the opacity. Cataracts can also be of varying density and maturity. Typically symptoms of cataract include the vision becoming blurry or smudgy, a change in the power of the eye and glare. Generally glasses will not be able to fully return the vision to normal, as the problem is deeper within the eye.
Not all cataracts require surgery, but surgery may be indicated if the patient has symptoms, some types of glaucoma can be managed better following cataract surgery and dense cataracts may preclude an adequate view of the back of the eye which is important for the assessment and treatment of retinal diseases. Patients with cataracts are assessed on an individual basis and your doctor can discuss the specific indications as they pertain to you.
Cataract surgery, which is the only treatment for cataracts, is performed under a local anaesthetic generally with the patient awake. This minimises the anaesthetic risks to the rest of your body.
Preoperatively, a number of drops are instilled to anaesthetise the eye, to minimise your risk of infection and to dilate the pupil. This facilitates access to the cataract, which sits in the middle of the eye behind the iris (pupil).
Cataract surgery is performed through tiny (micro) incisions made in the cornea (front window of the eye) to gain access to the cataract. The cataract sits within a fine capsular bag that is supported by ligaments (zonules). In younger patients this capsular bag is elastic and able to change the shape of the lens to accommodate on images up close. With age this ability is lost and this process is called presbyopia.
A precise circular incision (capsular rhexis) is made in the capsular bag to gain access to the cataract. The initial corneal incisions as well as the capsular rhexis can be made manually or preoperatively using a laser. The latter is called laser assisted cataract surgery (LACS). The cataract is then removed using phacoemulsification, this utilises energy to emulsify the hardened cataract into a paste for removal.
After the cataract is removed in stages, the hard nucleus first and followed by the soft outer shell or cortex, an artificial intraocular lens (IOL) is placed ideally back into the natural capsular bag. These IOLs are all custom made and measurements are taken using an IOL master preoperatively as part of the cataract workup. From these measurements the surgeon can determine, using multiple and various formulae, the best IOL power for the patient. This allows each individual patient to have a custom made intraocular lens implant to replace the cataract once it is removed. The power of this implant is predetermined and you can discuss the various options for distance vision, near vision, treatment of astigmatism, monovision and multifocal IOL with your surgeon. However, glasses may still be required after surgery as the surgery is aimed to remove cataracts and not glasses!
As with any surgery there are risks involved with both the anaesthetic and surgery. Risks include infection, bleeding, retinal detachment, posterior capsular tear and and the chance of a secondary operation. The eye can become inflamed, the cornea cloudy, the pressure in the eye elevated and the macular may become swollen. The other eye can be affected by a very rare inflammatory condition called sympathetic ophthalmia. Sometime after surgery the capsular bag in which the IOL sits can become cloudy and this can be cleared with YAG laser capsulotomy.
If the eye has pre-existing diseases such as an abnormal cornea, glaucoma, macular degeneration, high myopia or previous surgery the cataract surgery may have increased risks. The way these risks affect you will be covered in more detail by your surgeon.
Most of the serious complications are uncommon and cataract surgery remains one of the safest, most common and effective operations performed today.
