Future Optometrists

AUTOREFRACTOMETRY OR OPTOMETRY      Refraction being the most commonly performed optical procedure has been widely developed.      Though the conventional technique of retinoscopic refraction is an excellent method of objective refraction, it is a time-consuming procedure and not every practitioner manages to accomplish it accurately.      The refractometry (optometry) is an alternative method of finding out error of refraction by use of an optical equipment called refractometer or optometer.      Refraction being the most commonly performed optical procedure has been widely developed.      Though the conventional technique of retinoscopic refraction is an excellent method of objective refraction, it is a time-consuming procedure and not every practitioner manages to accomplish it accurately.      The refractometry (optometry) is an alternative method of finding out error of refraction by use of an optical equipment called refractometer or optometer. OPTICAL PRINCIPLES:      The pr

PROGRESSIVE ADDITION LENS      The concept of progressive addition lens has been around since 1907 when the first patent on progressive power lens was published by Owen Ave.      The early progressive lenses were rather crude in design. Varilux 1 was introduced by Essilor in France in the year 1959 and since then progressive addition lens have gained worldwide acceptance as the most performing ophthalmic lens for the correction of presbyopia because they provide comfortable vision at all distances.      They are successfully and advantageously replacing single vision and bifocal lenses. Growing popularity of progressive addition lenses has stimulated the search for advances in design and manufacturing technology of the progressive lenses.           This has enabled progressive addition lenses to develop from the early “hard” designs requiring extended patient adaptation time to current “state of the art” softer asymmetric design to the individually customized progressive lenses. Today

DISPENSING TIPS FOR BIFOCAL FITTING      Bifocal segments must be positioned so that the distance and near positions of the lens provide adequate fields of view for distance and near vision respectively. The fitting position of the bifocal segments should be decided according to the purpose for which they are to be worn. However, it is necessary to consider the positioning of segments in vertical and horizontal meridians. So while fitting the bifocal into a spectacle frame three factors must be considered: 1. Segment Inset 2. Segment Width, and 3. Segment Height. 1.SEGMENT INSET      Segment inset is specified as the difference between the subjects distance PD and near PD. In the normal range of PDs, the near PD for a reading distance of 40cms is 4mm less than the distance PD. Segment inset, therefore, is usually specified as 2mm for each lens. There are two reasons for insetting bifocal segment – to ensure that the subject’s line of sight will go through the segment at its optical cen