I know a little about this due to a research project I was involved in more than 30 years ago where I studied coatings on glass and plastic meant for optical applications, and because I too wear glasses.
Some years back, I bought a microfiber cloth marketed for cleaning glasses - this was before my optometrist included such a cloth in the eyeglass case that new eyeglasses come in. I only use the cloth on occasion, more to remove dust than facial oils. It seems to spread the facial oils onto the lenses in a uniform manner rather than remove them.
For the 60 years I have worn eyeglasses I have cleaned them with the same bar soap I use on my hands and dried them with facial tissues. When the lenses were made of plain glass with no coating, this cleaned them without damaging them. I never wore out glass lenses before my eyes changed enough to get a new pair or the frames got too loose or were damaged.
However, the plastic lenses with coatings that are used in most eyeglasses these days are more fragile, and the coatings do not last longer than a few years before they start developing defects. Facial tissues are not recommended for drying such lenses because a bit of grit in them could scratch the lenses, but that doesn't stop me from drying lenses with them, and I've only scratched a coating once. But I have noticed that the coating starts to delaminate (lift off the surface of the lenses) with time. The spots you are seeing are consistent with a hypothesis of delamination spots, as they would exhibit a rainbow effect. Soap doesn't cause them to appear; they appear on their own due to a mix of factors involved in the coating process.
I think most glass lenses these days are coated too, but I get plastic lenses because I am nearsighted enough to need a lot of correction. The plastic lenses are thinner and therefore lighter for the same degree of correction. I would expect delamination over time with the coatings on glass lenses as well.
You can't do anything about defects in the coating, and they will worsen over time. As long as the spots are small enough, you can't focus on them and so they don't affect how you see through the glasses. I wear my glasses until my eyesight has changed enough that I can tell that I need a new prescription. I just got a new pair of glasses two days ago, replacing the pair of glasses I had worn since 2019.
Re: Cleaning eye glasses?
Some years back, I bought a microfiber cloth marketed for cleaning glasses - this was before my optometrist included such a cloth in the eyeglass case that new eyeglasses come in. I only use the cloth on occasion, more to remove dust than facial oils. It seems to spread the facial oils onto the lenses in a uniform manner rather than remove them.
For the 60 years I have worn eyeglasses I have cleaned them with the same bar soap I use on my hands and dried them with facial tissues. When the lenses were made of plain glass with no coating, this cleaned them without damaging them. I never wore out glass lenses before my eyes changed enough to get a new pair or the frames got too loose or were damaged.
However, the plastic lenses with coatings that are used in most eyeglasses these days are more fragile, and the coatings do not last longer than a few years before they start developing defects. Facial tissues are not recommended for drying such lenses because a bit of grit in them could scratch the lenses, but that doesn't stop me from drying lenses with them, and I've only scratched a coating once. But I have noticed that the coating starts to delaminate (lift off the surface of the lenses) with time. The spots you are seeing are consistent with a hypothesis of delamination spots, as they would exhibit a rainbow effect. Soap doesn't cause them to appear; they appear on their own due to a mix of factors involved in the coating process.
I think most glass lenses these days are coated too, but I get plastic lenses because I am nearsighted enough to need a lot of correction. The plastic lenses are thinner and therefore lighter for the same degree of correction. I would expect delamination over time with the coatings on glass lenses as well.
You can't do anything about defects in the coating, and they will worsen over time. As long as the spots are small enough, you can't focus on them and so they don't affect how you see through the glasses. I wear my glasses until my eyesight has changed enough that I can tell that I need a new prescription. I just got a new pair of glasses two days ago, replacing the pair of glasses I had worn since 2019.