Cataracts Explained

What are Cataracts?

Cataracts form as the natural crystalline lens of the eye thickens and alters its shape with age. Recent evidence shows that from the age of 20 onwards these changes start to reduce the functional quality of vision. Initially the shape alteration increases the spherical aberration of the eye, a focusing error which reduces the functional quality of vision or contrast e.g. blacks fade to greys and so forth.

Incidentally, it was spherical aberration caused by errors in the manufacture of the focusing mirror resulted in the flaws in the early pictures from the Hubble Space Telescope.

As the lens ages further it loses its ‘zoom’ i.e. its capacity to alter focus from distance to near. As a result of this people in their 40s start needing reading glasses (a condition known as presbyopia). Further age-related deterioration in the lens leads to cloudiness and a loss of transparency. It is this loss of transparency or cloudiness of the lens that is known as a cataract.

What Causes Cataracts?

If you live long enough you will get a cataract. Apart from age, cataracts occur rarely as an inherited condition. Trauma, inflammation, metabolic diseases like diabetes and some drugs like steroids can also cause cataracts.

What Are The Symptoms Of Cataracts?

The visual effects of cataracts during the early stages are subtle. Symptoms include a rapidly changing spectacle prescription, increasing glare and dazzle in bright light conditions, poor tolerance of headlights when driving at night and coloured haloes around lights. As the cataract worsens, there is increasing blur and with time this blur can lead to total blindness.

What Is The Treatment?

Irrespective of the cause, the definitive treatment is cataract surgery, as to date no medical treatments have been shown to work effectively. The safety and results of refractive cataract surgery make it feasible to operate on cataracts at any stage of their progression.

The risks of surgery generally remain the same across all stages of cataract except for dense advanced cataracts where the technical difficulties can increase the risk of sight-threatening complications.

What Is the Best Time For Treatment?

The best time for refractive cataract surgery is when you as a patient feel that your poor sight is significantly affecting your lifestyle. You do not have to wait for the cataract to ripen to have refractive cataract surgery. You are the best judge of your sight and no vision test is capable of reliably measuring the effects of poor sight on your lifestyle.

Cataract Surgery Options

There are two types of cataract surgery options available: basic NHS surgery, and Advanced Refractive Cataract Surgery.

Basic NHS Cataract Surgery

A basic cataract surgery option (as offered on the NHS) would involve removing the cataract and inserting an intraocular lens to restore focus with limited success. The methods used to calculate the power of the replacement lens are relatively crude and can only correct a limited range of focusing errors.

Common focussing errors like astigmatism (irregular focus due to a misshapen eyeball), presbyopia (the universal condition of needing reading glasses in the forties) and spherical aberration (the focusing error which caused the problem with the Hubble Space Telescope) cannot be corrected using these techniques.

Furthermore, because focusing errors do not occur in isolation, it is quite common for patients to have a combination of long-sightedness or short-sightedness with astigmatism and presbyopia.

It follows that a basic small-incision surgery cannot achieve the full potential for quality vision in an eye with a cataract.

Advanced Refractive Cataract Surgery

This cataract surgery option was developed to enhance the ability of the surgeon to correct almost all known focusing errors at the same time as dealing with the cataract. This can correct the full range of hyperopia (long-sightedness), myopia (short-sightedness), astigmatism, presbyopia and spherical aberration resulting in the best possible quality of vision without glasses or contact lenses.

Sophisticated technology is used to assess the focusing system of the eye prior to surgery. This includes computerised slit scan corneal topography (corneal power/shape mapping), pupillometry (pupil size), and dual linear partial coherence interferometry (the most accurate and reproducible way of measuring the length of your eye). This information is used in combination with an assessment of your visual needs and lifestyle to generate a tailor made surgical plan. Additional surgical techniques to correct astigmatism are combined with state of the art replacement lens technology to achieve the best possible vision without glasses or contact lenses.

The vast majority of refractive cataract surgery patients are able to carry out most day-to-day activities without glasses or contact lenses. Many patients commonly end up seeing better without glasses than they have ever seen in their lifetime.

Who is Advanced Refractive Cataract Surgery for?

Are You a Good Candidate For Advanced Refractive Cataract Surgery?

Advanced Refractive Cataract Surgery is suitable for all patients with cataracts. Compared to basic cataract surgery as available on the NHS, Advanced Refractive Cataract Surgery gives you better vision without spectacles and carries no extra risk. It is thus suitable for anyone of any age with a cataract of any severity.

Irrespective of your prescription, if you have a cataract you are a good candidate for Advanced Refractive Cataract Surgery at Vision Surgery.

If you have been using glasses all your life, developing a cataract may be a blessing in disguise as Advanced Refractive Cataract Surgery can give you the best vision of your life without spectacles.

Anyone who is a good candidate for basic cataract surgery as available on the NHS is also a good candidate for advanced refractive cataract surgery. You don’t have to wait for your cataract to ripen or reach any stage of severity. The ideal time to carry out refractive cataract surgery is when you want to improve your sight.

Refractive cataract surgery is all about improving your quality of life – if you see better, you live better.

Advanced Refractive Cataract Surgery Preparation

Your decision to have Advanced Refractive Cataract Surgery should be a positive and informed decision based on an accurate assessment of the potential risks and benefits specific to your case. You should fully inform yourself as to the clinical reasons behind your treatment, the predictability of the procedure’s results and the timescales involved.

The first step in Advanced Refractive Cataract Surgery preparation is to arrange a consultation. An expert ophthalmic surgeon trained in the practice of refractive surgery and the diagnosis of corneal disorders should always carry this out.

This examination should include:

1. Refraction – A check on the focus of the eye.

2. Scanning Slit Corneal Topography – A map of the corneal shape and power.

3. Corneal Pachymetry – A measurement of corneal thickness.

4. Pupillometry – A measurement of the size of your pupil in the dark.

5. Keratometry – A measurement of corneal power; this data is useful if you end up needing a cataract operation in the future.

6. Dilated examinations of the retina – i.e. after drops are instilled to dilate the pupil so that the back of the eye can be clinically assessed also.

7. Wavefront Scan – This is a measurement of the focussing error of the eye which is much more sensitive and personalised. When the treatment is carried out using these measurements it is called wavefront based laser correction. A standard laser treatment is one which uses the spectacle prescription. The visual results are generally better with wavefront based treatments, provided the wavefront measurements used meet a set of quality criteria. If the wavefront measurement is of poor quality, better results are obtained using the glasses prescription.

Using contact lenses can produce inaccurate corneal measurements. It is critical to have a contact lens free period prior to these measurements. This period is ideally a week for soft contact lens and four weeks for rigid gas permeable lens users.

Advanced Refractive Cataract Surgery Process

Before Surgery

The first stage of the Advanced Refractive Cataract Surgery process is a comprehensive evaluation of the optical system of the eye. This includes refraction, scanning slit corneal topography, pachymetry, keratometry and pupillometry.

Almost all eyes have a combination of focusing errors and it is important to correct as many as possible in order to achieve the best quality of vision after surgery. At this stage an individual risk benefit assessment is carried and the decision to carry out surgery is confirmed.

Based on this evaluation an individual surgical plan is designed, with the aim of achieving the best possible vision for distance and near without glasses or contact lenses. This surgical plan is analogous to an optical prescription, and can be thought of as a surgical prescription to correct the focusing errors of the eye.

During Surgery

The Advanced Refractive Cataract Surgery process is normally carried out using a no-injection local anaesthetic technique. Some patients choose to have a general anaesthetic.

A 2.5 mm incision is made and the natural crystalline lens is removed using an ultrasound probe called a phacoemulsifier. The outer shell or capsule of the crystalline lens is used to encase the new intraocular lens. The intraocular lens is a special folding lens, which is inserted and unfolded within the natural lens capsule.

This way the new plastic lens has a natural covering and sits in the physiological position within the eye. The incision is constructed like a valve sealing itself without stitches. A protective plastic shield is taped to the eye and patients recover within a few hours and go home the same day.

After Surgery

Most patients are up and about as soon as they are back from surgery. The eye can feel a bit scratchy and light sensitive for a few hours. There are no restrictions on normal daily activities and there is usually a significant change in vision by 24 to 48 hours after surgery.

The eye settles down and heals gradually over the next 4 weeks. Eye drops are prescribed for 4 weeks. The second eye is operated on after the first eye has settled down and usually within 2 to 4 weeks.

Visual Recovery

Visual recovery starts within the first 24 hours and continues for 4 to 6 weeks after surgery. Depending on the intraocular lens used it can take your visual system up to 3 months or more to adapt completely to the new improved vision. The final focus of the eye depends not just on the surgery but also on the way the eye heals.

This healing process is variable and sometimes can result in a suboptimal focus. In these rare cases a second enhancement operation is carried out to fine tune the focus. This enhancement surgery can be inserting an additional intraocular lens, exchanging the intraocular lens, astigmatism correction incisions or laser surgery.

Getting Started

The first step in the Advanced Refractive Cataract Surgery process is to attend a consultation so that your eyes can be examined and your suitability assessed for treatment.

John

“I could see everything clearly that initially I thought I’d forgotten to take out my contact lenses, then I remembered that, no, this was my own eye-sight now.”