General rules

• As a rule both eyes have to balance, that is your prescription should not differ more than 3 dioptres between both eyes.
• The surgeon will often aim for 0d (or -1.0d if you already have a 'minus' prescription).
• The measurements of your eye are never completely accurate, so if the surgeon aims for 0d he may get -1.0d - +1d, and a few patients will have and even greater variation.
• There is always some astigmatism after surgery….getting to an accurate 0d is nearly impossible.
• The surgeon will try to keep your prescription similar between both eyes, and try and achieve 0.0d, so you will not need distance glasses.
• Reading glasses need an extra +2.5 or so to your distance prescription. So even if you have no distance glasses, you will still need reding glasses
• this is just an expanation, and will not be accuarte for all patients

Here are some common examples of options

Case1...If your prescription is about +1.0d or -1.0d. in both eyes

• Before surgery you did not wear glasses for distance vision but you will have needed reading glasses.
• The surgeon will try to keep your prescription similar, that is to try and achieve 0.0d, so you will not need distance glasses.
• You will of course need reading glasses, which will be an extra +2.5 or so to your distance prescription.
• These glasses may be reading glasses only, varifocals, or bifocals. (Which of these you will be given depends on what you want/what your optometrist advises.)

Case 2..If both eyes are +5.00 or more

Here there is a dilemma. If the eye being operated on achieves 0.00 (that is perfect distance vision without glasses), and the other eye is still +5.00, both eyes may not 'balance'.

So the options include,

1. Operating on the first eye and achieve 0.00; then operating on the second eye as well (a different day), so both eyes achieve 0.00.

2. trying to balance both eyes, so the surgeon may try to achieve +3.0d in the operated eye…both eyes should still balance. You will still need glasses, but they will not be as thick. (And you will not need a second operation to balance the two eyes.)

3. A much less common option now... operating on the first eye and achieve 0.00; then using a contact lens in the other eye to balance both eyes.

 

Case 3..If both eyes are -3.0d

Here there is another dilemma. If the eye being operated on achieves 0.00 (that is perfect distance vision without glasses) you will need reading glasses in that eye.

So the options include,

1. trying to achieve -3.0d after the operation so here is no change…you will need distance glasses, but see well for reading without glasses. Often varifocals are best. (And you will not need a second operation to balance the two eyes.)

2. trying to achieve 0d after the operation ; but then you may not balance (and may need the other eye operating on) and you may need reading glasses

3. Operating on both eyes and try and achieve 0d in both eyes, so you will not need distance glasses. You will of course need reading glasses, which will be an extra +2.5 or so to your distance prescription, so you may need a separate pair of reading glasses or varifocals.

4.  Operating on one eye and try and achieve 0d. To balance  the other eye, the other eye may be prescribed a contact lens. Then you would not need distance glasses.
You would of course need reading glasses, which will be an extra +2.5 or so to your distance prescription, so you may need a separate pair of reading glasses or varifocals.

Case 3..If both eyes are -8.0d or more

Here there are several options

1. trying to balance both eyes, so the surgeon may try to achieve -5.0d in the operated eye…both eyes should still balance. You will still need glasses, but they will not be as thick. (And you will probably not need a second operation to balance the two eyes.)

2. trying to achieve -3.0d after the operation; both eyes may not balance though, and you may need the second eye operating on to balance. But if you are -3.0d you will not need reading glasses for that particular eye, although you will need distance glasses.

3. Trying to achieve 0d after the operation; both eyes will not balance though, and you will usually need the other eye operating on. You will need reading glasses, but you will not usually need distance glasses.
(In fact if detailed sight is needed as for driving, you may need distance glasses, but the lenses should be thin.)

Cases..others