Diabetic Retinopathy - left eye.

My mother had a cataract surgery in the left eye in the month of January, 2020. However, she started complaining of some swelling in the left eye and lesser visibility in the month of september. The issue came to light when she tried to go with the recommended specs lens and could not see much from the left eye with the recommended left eye lens, its blurry, visible but cant read well. For right eye it worked fine and not much swelling is felt. Post visiting the same hospital (Center for Sight, Delhi), doctor said that she has retina issues in both eyes and would need to undergo some treatment with some expensive injections for period of next 6 months with 80 % chances of improvement.    Help us understand the procedure and timeline to heal this (injections vs lasic), economical way to work this out with more assurance and the intricacies and precautions to be taken pre and post procedure along with timelines. When shoud be ideally start the procedure knowing that its already delayed