| As a layman, it is not easy to evaluate the quality | | | | are uncomfortable with the design you can |
| of your lens at home without consulting | | | | always get a reversed one through a consultation |
| professionals. However, you might as well try an | | | | with your doctor. |
| evaluation at home by following a careful step by | | | | - The concentric design lenses are the most |
| step process. | | | | common types. In this type the inner lenses are |
| - Hold the glass lens a minimum one foot away | | | | responsible for distant vision or the other way |
| from the eye and then look at some distant and | | | | round. Other kinds like the translating design have |
| stationery object like lamppost or something else. | | | | the distance correction above the nearness |
| - Try and move the glasses from one side to | | | | correction centre. Distinguished by a fine line, the |
| another. | | | | lenses don't shift even when you blink because |
| - If the view of the distant object in the lens is | | | | their bottom is totally flat. |
| unclear and interrupted by breaks and irregular | | | | - If the lenses are of the monovision kind then |
| waves, then you know that your lens is of a poor | | | | while one lens has nearness correction, another |
| quality. | | | | one has the distance correction lens. In this case, |
| - Also note if there are scratches or pits on the | | | | you need to know which is your dominant eye. A |
| surface of the lens. This might be caused either | | | | consultation with the doctor can tell you that and |
| by poor polishing methods or small accidents. | | | | accordingly you should be wearing the distance |
| Though apparently insignificant these might lead to | | | | correction in that eye. |
| problems with vision if not corrected. | | | | - Another kind of lenses is the simultaneous ones |
| - The junction of the bifocal section of your | | | | through which you can focus on both near and |
| spectacles is a part you ought to carefully | | | | far objects simultaneously. The lenses for |
| observe. Not only should the lines here be clear | | | | nearness and distance corrections are placed in |
| and sharp but also there should be equality | | | | concentric circles. The reflections of light from |
| between the size and shape of the segment | | | | near and distant objects reach your eyes and |
| from left to right. In case there seems to be a | | | | help you to focus at both at the same time. |
| visual coloring it is a sign of poorly fused bifocal | | | | Today thanks to advancement in technology, |
| blank. | | | | researchers are trying to use bifocals to replace |
| - The fitting of the lens into the frame is done by | | | | all the cumbersome methods of limited vision. |
| what is known as technical glazing. The edge of | | | | Innovative designs are shaping the new materials |
| the lens hence should be at its thinnest and should | | | | available and thus this way each and every lens |
| fit perfectly into the frame without any gap.To | | | | can be specifically designed to cater to everyone's |
| check if your lens has poor glazing you can slide a | | | | requirements. One of the latest products from |
| piece of paper at the edges and see if it passes. | | | | the optic stable is a liquid crystal layer fitted |
| The various kinds of lenses are:- | | | | between two glass substrates. The varying |
| - In the special asferic kind of design the lenses | | | | power of the lens can be changed by changing |
| correction is in the centre. Since the distance | | | | the refractive index with the help of electricity. |
| correction is in the central zone, therefore if you | | | | |