The concern about presbyopia in the forties after Lasik in the twenties or thirties is totally relevant.
The truth is Lasik can be repeated or “enhanced”, either to treat residual short-sight or overcorrection causing ling-sightedness, so long as the corneal measurements allow it.
Repeat Lasik to improve near vision after previous Lasik for short sightedness can and has been done, and done well before. However, the potential candidate needs to understand what it involves. Lasik for presbyopia works on the basis of
1) monovision, in which one eye is made slightly short-sighted to focus near, hence sacrificing far vision somewhat in this eye, and the other eye (the dominant eye) is left sharp for far. This often works well when both eyes work together (binocularly).
2) adjustment of sphericity. This refers to adjustment of the higher order power of the cornea, to make its shape more able to focus over a slightly wider range of distance. This is usually combined with monovision Lasik treatment, in the eye meant to focus near. This is possible in several more advanced “excimer-based” Lasik treatment
In all cases, adjusting to focus near after previous Lasik which targeted for zero power will mean losing some sharpness for far vision in one eye, in return for improved reading /near vision. This is the “give and take” of such cases.
This principle is no different from, for instance, cataract surgery employing monovision strategy after previous Lasik.
I hope that my answer, which may differ from others, are able to give a different perspective of this topic.
Cheerio
Daphne Han
Senior Consultant, Ophthalmologist
