Fragmentation: When plastic lens breaks, it breaks into larger fragments than their glass counterparts. Furthermore, the fragmented pieces are not as sharp as glass.
Fogging: Mid Index lenses are less likely to fog-up than glass lenses because it responds more favorably to temperature changes.
Weight: Glass lenses are approximately 2X heavier than plastic lenses of similar size and shape. The lighter weight provides the wearer greater comfort.
Reflections: Mid Index lenses have much lower internal reflection and surface glare than glass materials.
Tinting: Mid index lenses are also tintable, so you can get that pair of sunglasses you' ve been eyeing for so long.
Fogging: Mid Index lenses are less likely to fog-up than glass lenses because it responds more favorably to temperature changes.
Weight: Glass lenses are approximately 2X heavier than plastic lenses of similar size and shape. The lighter weight provides the wearer greater comfort.
Reflections: Mid Index lenses have much lower internal reflection and surface glare than glass materials.
Tinting: Mid index lenses are also tintable, so you can get that pair of sunglasses you' ve been eyeing for so long.
All of lenses have excellent impact resistance to protect the wearer from injuries. The lenses have passed both the European Committee for Standardization (CEN) Strength Norm Test and the US Food and Drugs Administration (FDA) Balldrop Test.
Lenses have a specific gravity of 1.17 g/cm3. Not only is the material lighter, because of a higher index refraction of 1.57, less materials needed to be used to make the prescription.
All of lenses have excellent impact resistance to protect the wearer from injuries. The lenses have passed both the European Committee for Standardization (CEN) Strength Norm Test and the US Food and Drugs Administration (FDA) Balldrop Test.
FDA Ball Drop Test Parameters:
1. The impact test will consist of a 5/8 inch steel ball weighing approximately 0.56 ounces
2. The ball should be dropped from a height of 50 inches from the horizontal upper surface of the lens
3. The geometric center of the lens should be struck by the ball within a 5/8 inch diameter circle
4. There cannot be anything restricting the fall of the ball
5. A tube may be used to guide the ball to the lens; the ball may be dropped through a tube extending to within approximately 4 inches of the lens.
1. The impact test will consist of a 5/8 inch steel ball weighing approximately 0.56 ounces
2. The ball should be dropped from a height of 50 inches from the horizontal upper surface of the lens
3. The geometric center of the lens should be struck by the ball within a 5/8 inch diameter circle
4. There cannot be anything restricting the fall of the ball
5. A tube may be used to guide the ball to the lens; the ball may be dropped through a tube extending to within approximately 4 inches of the lens.