let me explain to you a little about PCO.
When a cataract surgery is done, after removing the cataract a thin membrane called posterior capsule is left behind on which the intraocular lens
is implanted. This posterior capsule is transparent, enabling clear vision. But with time in some people this posterior capsule gets thickened or opacified leading to PCO (posterior capsule opacification) causing decrease in vision. Once the PCO is cleared with laser, the original vision is restored.
Other conditions that can cause a decreased vision are any bleeding or hemorrhage in the eye, posteriorly or anteriorly. But in such a case the decrease in vision is sudden and profound and as slowly the blood is absorbed, the vision improves slowly over weeks. Other possibility is an infection or inflammation of the eye - but in that case usually there is pain, redness etc.
So, in your case the decrease in vision was because of PCO.
Hope this information helps.
Also, I would like to remind you that the previous answer was not accepted. Kindly do that so that I get credit for the interaction.