Subscribe Feed (RSS)Failing Vision After Cataract Surgery
May 30th, 2010 by admin | Filed under Uncategorized.Sometimes in the months and years following a cataract operation the vision within the eye can gradually diminish. For the patient the effect can be rather like the original cataract recurring. One common cause for this is a phenomena called “Posterior Capsule Opacity”. It is also sometimes referred to as “after cataract”. What is it?
This can be explained by thinking of the eye as a camera. Like a camera the eye contains a lens. This is positioned within the eye just behind the pupil. This natural lens of the eye has the shape of a tiny discus, similar in size to a “smartie” or “M & M” sweet. A cataract occurs when this lens becomes hazy and obscures vision. To remove a cataract the surgeon must therefore remove the lens from the eye.
The lens of the eye has a thin membranous outer layer. This is called the lens capsule. As with a discus there are two main surfaces to the lens capsule. The front surface is called the anterior capsule and the rear surface the posterior capsule. During modern cataract surgery a small piece of the anterior capsule is removed in order to gain access to the cloudy interior of the lens. The art of cataract surgery is to remove this cloudy inner lens material whilst preserving the posterior capsule that lies behind it.
Returning to the “smartie” or “M & M” analogy a cataract operation is a bit like removing a tiny piece of the sugar coating from one surface so as to remove the chocolate within; but leaving behind the rest of the sugar coating intact! The effect is to create a little empty sac with a hole in its front surface. In the eye this is called the capsular bag. A replacement artificial lens (called the lens implant) is then inserted into this bag. The posterior capsule lies behind this lens implant and partially supports it.
The posterior capsule is extremely thin and delicate. Its centre is thinner than a single red blood cell! Eye surgeons make every effort to preserve the posterior capsule intact during surgery. It helps maintain the natural compartments within the eye. It separates the fluid filled space at the front of the eye from the jelly (called the vitreous) that fills the main rear cavity of the eye. It also stops the vitreous from moving forwards and interfering with the operation.
At the end of surgery the posterior capsule is clear and transparent. In some patients it may become hazy or opaque during the following months and years. This is “Posterior Capsular Opacity”. Eye surgeons refer to it as “PCO”. If this happens and it impairs vision significantly it can be treated using a laser. This is a quick simple painless outpatient procedure taking just a few minutes to perform. This treatment is called a “YAG laser posterior capsulotomy”. The aim is to create a small opening at the centre of the posterior capsule and thus clear the line of vision. If there is nothing else wrong with the eye this treatment should restore vision to that first achieved after the original cataract operation.
The information within this article is for general interest only. These are the personal views of Consultant Ophthalmologist Mr C J Heaven. If you have a problem with your vision then always seek the advice of your own eye specialist.
Mr Heaven is based at The Royal Albert Edward Infirmary in Wigan, in the north west of England. His special interests include small incision cataract surgery and various forms of refractive surgery. For more details see: lens-exchange.co.uk lens-exchange.co.uk
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