Poly(methyl methacrylate) is used medically in contact lenses and cataract replacements due to its refractive index, it is used industrially due to its strength and its transparency and it is used because it is light compared to glass. Medical uses of poly (methyl methacrylate) The first advantage of Pmma over other materials is medical. PMMA is used in many areas of the medical field; From dentistry to orthopedics, poly(methyl methacrylate) has revolutionized the way we live. PMMA is widely used today as an implant fixation due to its ability to fill cracks and create smooth surfaces into which bones and ligaments must be placed and prevent unwanted movement. Another medical use of pmma is in ophthalmology, because polymethylmethacrylate has very good optical properties. PMMA transmits up to 93% of visible light, which is much higher than glass which only transmits about 85% of light. (Koleva, M, 2016) The refractive index of pmma is due to its crystalline rather than amorphous form.