I am sorry to hear about the whitened scars that you have after double eyelid surgery. However, do note that it is common to have a line (crease) along the pre-tarsal area for some individuals even though they may not have had surgery, but a white line is often a tell tale sign of surgery and it's often due to a stretched scar.
Hypopigmented scars are one of the hardest scars to treat conservatively. As the previous 2 doctors have mentioned, the scars are hardly visible as our eyes are often opened. Notwithstanding, I do understand the frustration along with the questions that are asked when people notice the line upon eye closure. I am unable to comment specifically as I have not seen your post-surgery photos.
Laser treatments such as fractionated lasers can help to reduce the scarring and also induce pigmentation to obtain an improvement in scar appearance. You will need multiple sessions for this. Depending on the severity of the scar, this may be all that you need. The other option would be to do a scar excision and re-suture. For that the downtime would be about 1-2 weeks.
I hope I have answered your questions. Have a great week ahead.
