Before the age of forty years , the lenses have the same power over their entire surface. We talk about focal plain glass
After quarantine presbyopia sets in near vision becomes painful , and we pass to progressive lenses , the top of the glass for easy viewing from a distance, the middle of the glass for easy viewing in medium-distance and lower glass for easy viewing closely ; talking glass multifocal or progressive. Why does one progressive lens ? Because the power of the lens is progressive from top to bottom , in order to see its progressive lenses , you keep your head up to see ahead, chin slightly raised to see average distance as the computer screen , and chin raised to read more closely about a foot ..
ON WHY YOU AFRAID TO ADAPT TO PROGRESSIVE LENSES ?
The progressive power lenses are not in the same from top to bottom of the lens , the vision is marked only if the eyes are in front of the appropriate portion of the glass :
the upper third for distance ,
means to display the third half distance of the order of 40-70 centimeters ,
the lower third for near reading especially .
In addition , both eyes must stay in the middle of the lenses , in front of an area of maximum sharpness . If one or both eyes deviate from this central area , the look falls into a zone of lower sharpness, and there is discomfort , which could cause blurred vision, eye pain etc. .. and there is only one desire is to remove his glasses , and it is the abandonment of progressive lenses.
Fortunately, the quality of existing progressive lenses is much more comfortable than the first generation , dropouts are more rare, the central areas of sharpness are wider, and now , when the eye falls on the edges of the glass , the view is blurred, that during the first progressive lenses.
During a bad adaptation to progressive lenses , your ophthalmologist prescribes oculomotor balance , looking for a deviation of the eyes , either within or outside said hétérophorie , which prevents eyes properly follow sharp areas central progressive lenses. It is a muscular problem . Most often, the muscles do not take your eyes perfectly straight , the latter deviate outside , it is called convergence insufficiency . Rehabilitation sessions are prescribed to strengthen the eye muscles .
History : The first progressive lens was invented by the French company Essilor , N ° 1 worldwide in the optical , called Varilux . Since all progressive lenses are abusively called varilux as Frigidaire , the first refrigerators . It is the fourth generation of progressive lenses.
If the eye falls outside the central area of sharpness, vision is not as good and there discomfort . This is why we must ask your Optician the latest generation of progressive lenses , where the optimal central area is wider .
