Progressive lenses are used in eyeglasses. They are used to correct presbyopia and other visual disorders. They are also known as multifocal lenses, graduated prescription lenses or progressive addition lenses (PAL). These progressive lenses are characterized by a range of increasing lens power. This is an added lens power to the wearer’s actual lens power.
Advantages of Progressive Lenses
Progressive lenses are attractive. They avoid the image-jumps created by the trifocal and bifocal lenses in the visual field. They have a seamless, smooth gradient of lens powers for a clear vision. Another advantage is that the eyeglass wearer can adjust the additional lens power by simply tilting his/her head.
Disadvantages of Progressive Lenses
- Image distortion: It occurs when the power gradient creates regions of aberration. This results in poor visual resolution. This blur in the vision depends on the quality of the progressive lenses. Most clinicians suggest that individuals should wear progressive lenses in the early stages of presbyopia.
- Loss of peripheral vision: It occurs due to the narrow vertical range of normal vision. Most wearers complain of difficulty in seeing more than 25% of a computer monitor.
- Fitting: Progressive lenses demand careful placement. Incorrect fitting can cause problems which include on-axis blur, narrow field of vision and clear vision in one eye only.
- Cost: These lenses are expensive because professional service and manufacturing costs are high.
Points to Consider
New wearers may find it difficult to adjust to progressive lenses as they may need some accommodation period. This time is required as the brain needs time to adjust to the progressive lenses. They may experience some side effects like dizziness and headache. It is generally suggested that during this period (,) progressive lenses be removed for some time. It is usually replaced after the side effects have subsided.
