What determines your outcome after cataract surgery? Most people view cataract surgery as a simple procedure with a guaranteed outcome of clear distance vision without glasses. Cataract surgery is a complex micro-surgery that takes 7-10 years of surgical training to perform well and with a low risk of complications. Assuming that you are having surgery by a consultant ophthalmologist who is an experienced surgeon, how predictable is your post-operative result and vision.
On of the critical tests before cataract surgery is called biometry. Biometry measures various anatomical features of your eye including corneal curvature, eye ball length and natural lens position. This information is fed into a formula that predicts the outcome from a specific lens implanted into the eye. Unlike a pair of glasses where your optician can ask you whether your vision is clearer with one lens or another, your eye surgeon needs to predict the lens strength that will give a certain result. In other words for each patient the formula will predict that X powered lens results in virtually no prescription and clear distance vision.
A typical biometry read out with lens predictions
If everything was that simple everyone would always have perfect results. However, modern lens prediction formulae are at best accurate to within +/-0.5 dioptres (the unit of a glasses prescription) in 70% of people and within +/- 1 dioptre in 90% of patients. 10% of patients can be outside these limits. Astigmatism may also affect clarity of post op vision. Some of these patients will require glasses for their best possible vision.
Whilst modern cataract surgery is highly successful and life enhancing, outcomes are determined by predictability of lens formulae. For the majority of people this is perfectly fine, but if you are paying to have a multifocal lens then you obviously want to have perfect vision. For the average cataract surgeon faced with a unpredicted outcome and hence a patient with blurred vision after multifocal lenses the option is to either perform a lens exchange operation or encourage the patient to simply wear glasses. The other less invasive and more precise option is the ability to perform laser eye surgery to refine the outcome of surgery to achieve perfect vision. This can eliminate residual prescription and astigmatism.
Choosing a surgeon that is able to perform laser eye surgery as well as cataract surgery is beneficial for the simple reason that lens prediction isn't exact and because this allows your surgeon to achieve your best potential vision with all types of lens implants.