The practice shows that in everyday life we encounter ever-growing demand for better visual acuity at all viewing distances. The presbyopic population needs correction to far, near and intermediate distance with different dioptric powers. PAL lenses seem to be a comfortable solution. The object of the present study is the analysis of the factors determining adaptation to progressive addition le...

PURPOSE Whether either natural emmetropization or compensation for imposed spectacle lenses requires the visual system to distinguish myopic from hyperopic blur is controversial. Some have argued that the visual system need only respond to the magnitude of the blur. This study was undertaken to test whether adding large amounts of astigmatic image blur would cause myopia and interfere with comp...

PURPOSE To assess the efficacy of the Tetraflex (Lenstec Inc) intraocular lens (IOL) to provide enhanced near reading ability and spectacle independence relative to a monofocal control IOL in bilaterally implanted eyes tested binocularly. METHODS A prospective, age-matched, non-randomized US Food and Drug Administration clinical trial of 255 Tetraflex and 101 monofocal IOL control patients wa...

The distance between the screener and the student (usually 6 metres) should be measured and marked appropriately. The student’s chair may move around, so make a mark on the floor where the front legs of the chair should be. Check that the chair is in the right place before assessing each child. If using a standard, unlit visual acuity chart, the room should be well lit, taking care to avoid ref...