Presbyond® Laser Blended Vision
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Presbyopia is the term given to the loss of the eyes ability to alter its focus from distant to near objects. It is an age related condition which affects everybody at about 45 years of age.
Presbyond® Laser Blended Vision is something every potential laser patient should consider but particularly patients over the age of 40.

Presbyopia can come as a bit of a shock and can be very frustrating. Patients that have previously been blessed with excellent eyesight now need reading glasses. Patients that already wear spectacles now need two or three different pairs of spectacles to focus distant, intermediate and near objects. Some patients opt for varifocal design spectacles to allow focussing at all distances, but these have significant limitations and can be difficult to accept.
It is important when thinking about Presbyopia that patients consider at least three separate focal distances.

• Distance vision (from a few meters to infinity)
• Intermediate vision (say 50cm to a few metres)
• Near vision (about 30-50cm).

For many years Opticians have provided, particularly contact lens wearers, with a technique called Monovision. Monovision means that opticians will focus one eye into the distance and the other eye much closer for reading etc. It can work very well for younger middle aged patients who still have a little flexibility in their eyes focussing system, but, with increasing age a patient’s depth of focus or accommodation will decrease and the reading strength in the reading eye will need to be increased accordingly. This ultimately creates a blur zone for intermediate distances (e.g. the dashboard of a car, prices in a shop window). We only have two eyes and we need to consider the three focussing distances as above. Also, as there is now a much bigger difference between the two eyes, monovision becomes more difficult to tolerate.

For Example - A younger eye, say 46 years of age, may only require 1.5 units of monovision because the eye still has some internal flexibility and can cope with distance and intermediate focusing but just requires a small amount of extra help for close work. This degree of monovision is generally tolerated very well. Monovision with only a small difference in power is called Micro-monovision.

The older eye on the other hand, say 55 years of age, will have now lost all of its internal focussing ability and will require 2.5 or eventually even 3 units of monovision (full monovision) to allow close reading focussing. But with one eye focussed quite close at say 40cm and the other eye focussed in the distance, these patients will have to accept a blurred intermediate zone.

 

The image represents full monovision correction without the benefit Presbyond.

 

Due to the difficulty that some patients have in adapting to full monovision correction, many refractive surgeons, Sheffield Vision Centre included, have historically provided patients with a micro-monovision visual correction. Most patients will adapt to this lesser degree of monovision very well indeed and the younger patient (under 50) may be free from spectacles altogether and therefore very happy with their choice. However, as the eye ages, reading glasses for closer focus (40cm) are inevitable, especially if the light level drops. Older patients are generally still very happy with their choice as they are usually free from spectacles most of the time but just wear spectacles for specific tasks where maximal acuity or concentration is required.

Laser Blended Vision takes monovision to the next level. Complex wavefront guided laser ablation profiles expand the depth of focus available to each eye. So whilst the adaptation is similar to micro-monovision the expanded depth of field allows for a wider range of focus to be achieved reducing dependence on spectacles as far as is possible.
One eye is profiled to allow full distance vision and some mid range vision and the other eye is profiled to focus at mid range (70cm) but allowing for some closer focus to be achieved. In such a way Presbyond Laser Blended Vision aims to reduce a patient’s need for spectacles to the absolute minimum.

The expanded depth of focus with Presbyond Laser Blended Vision is shown here diagrammatically.

 

Important -

All patients, at whatever age, need to be aware of the aging changes that will take place in their eyes eventually. Patients need to consider their long term visual needs very carefully, as increasing age brings compromises that must be understood and accepted.

Younger patients and some older patients may choose Balanced Laser Vision Correction to focus both eyes into the distance. This balanced distance vision may be chosen by younger patients who are not concerned yet about the effects of aging or by older patients whose distance visual demands are absolutely paramount and they do not want to wear spectacles to achieve this level of satisfaction. So for example, a police rapid response driver or a tower-crane operative, perhaps a company representative that drives long distances each year often in the dark may prefer balanced full distance vision correction in each eye. Patients choosing balanced laser vision correction will benefit from maximal distance acuity, their eyes focus will be balanced, allowing them maximal depth perception and best possible night vision. However these patients will be inconvenienced by the need for close work glasses with increasing age. If over the age of 45, they have chosen the compromise “Clarity over Convenience”.

Other patients will accept a subtle compromise in absolute binocular visual clarity and choose Presbyond Laser Blended Vision to allow maximal freedom from the burden of spectacles. These patients will have chosen “Convenience over absolute binocular Clarity”. They should be free from spectacles for most general day to day tasks. One eye dealing with distance vision quite acceptably and the other with intermediate and some close work acceptably.

It should be pointed out that patients choosing Presbyond Laser Blended Vision because they want maximum freedom from glasses as they age, always retain the option to wear spectacles (or a single contact lens) to balance their eyes and give maximal binocular acuity for specific tasks. For example a fair percentage of patients still wear spectacles to maximise vision for night driving or may wear spectacles for prolonged periods of intense close reading.

 

Presbyond Laser blended vision is primarily available with Lasik treatments.

Full Monovision or Micro-monovision is available with ReLEx SmILE.
Contact lens trials to approximate treatment plans can be arranged if required.