Reasons why you may not see 20/20 post surgery?
Some folks are disappointed by their cataract surgery results. They usually present to me that “the cataract surgery did not take” or “the vision never came back after I had the cataract out”.
It is worthwhile here to make the distinction between (acuity refers to distance vision):
 BEST corrected 20/20
 UNcorrected 20/20
 BEST corrected under 20/20
 If you are “Best corrected 20/20” post-surgery – This means that with glasses, you see 20/20 but without glasses you are below perfect 20/20 distance vision. Common reasons for this can be: uncorrected residual astigmatism, poor pre-surgery measurements (e.g. disrupted by dry eye), predictive algorithm for lens selection was not accurate, incorrect lens was selected, healing caused unexpected astigmatism, lens implant centration/rotation not exact. This is not a bad thing! Being best-corrected 20/20 was the goal of cataract surgery only a few years ago.
2] If you are “Uncorrected 20/20” post-surgery – This means that without glasses, you see perfect (20/20) in the distance. This is the best result but vision could still fluctuate due to such things as dry eye or floaters. You could also be “uncorrected 20/20” and still have trouble with other things e.g. night glare or transient blur secondary to floaters.
3] If your BEST corrected is under 20/20 – This means that no matter what we do with glasses, your vision does not come back to 20/20. Typically – but not always - this is not a problem with the cataract surgery itself but rather a pre-existing or concurrent problem that limited the outcome of the cataract surgery. Cataract surgery can 100% fix your vision only if your vision limitations are 100% related to cataract. If you have vision loss 25% related to macular degeneration and 25% related to diabetes and 50% related to cataract… the most that cataract surgery can improve your sight is 50%. The two most common reasons that I see for disappointment after cataract surgery are: retinal complications of diabetes and age-related macular degeneration. Best vision under 20/20 is sometimes temporary. Talk to your eye care professional to understand exactly why you are not 20/20 post surgery and the prognosis.