Corneal brown discolouration

[Formula]

Hi I'm an optometrist and just trying to find some information.

I saw a male 30 year old Indian who had lasik 2 years ago. Went from -10 doptres to now about -1.50 dioptres.
Visual acuity is good: R eye 6/7.5+ L eye 6/7.5+ No complaints

I saw central epithelial (or just anterior stomal) brown pigment or discolouration (like a brown burnt patch). I don't think there is any significance but just need to make sure. So please advise - do you know what they are?

I could not find much information on the internet because I don't have a specific name I can search for but my research was heading towards IRON deposits.

I need this information to decide if further medical attention is required.

Thanks