india dust problem in optical drives
Laser can worn off because its simply made of a semiconductor (a LASER diode, LASER-ED). The optical problem...the glass (or lens) is unlikely to worn off just like you say.
But, in a dvd optical system, the lens is placed on a spring-damper system for focusing purpose. To control its focusing, the lens can move in several direction controlled by electro-mechanical system (it uses magnetic force actually to control the movement of the lens).
So it is likely the whole optical system can be easily damage if a certain condition applied...such as: unstable mains voltage, too many mechanical shock, bad disk that cause the lens change its focus rapidly, improper ventilation that can cause heat.
Anyway, if your PS2 disk is damage...you dont have to buy a new system...just repair it or exchange it with a PC DVD drive.