Does it have to be local? There are any number of places in the US (and I am sure other places as well) that will take a mask shipped to them and weld on custom ground lenses to the inside of the mask and ship it back to you. I have been getting this done for 30 years, and now I have bifocals ground into the mask lenses. Any optical house can mark the pupil spots on the mask for you (or you can do it yourself with the assist of one sharp eyed helper and a marking pen), and then you can send it to the lens company for processing. There are several places listed on the internet who do this, but make sure the mask really fits you well before this alteration. Also, it wouldn't hurt to tell the lens company which mask you are going to use, as there are occasionally problems with interference between the internal edges of the lens and your face if the prescription is too strong and/or the internal mask volume is too low. Some lens companies even stock the masks, so you would not have to ship the mask to them but just buy one of theirs and have them convert it. Lots of options. I don't know about Manila, but a lot of scuba shops here in the US will arrange this for you also.