1/4. Piggyback posterior chamber multifocal intraocular lenses in anisometropia.A 63-year-old white man with anisometropic hyperopia presented with cataract in both eyes. He had uneventful temporal limbal phacoemulsification with intracapsular placement of a multifocal 3-piece silicone intraocular lens (IOL) in his right eye (model SA-40N, Allergan, Inc.). One week later, 2 intracapsular 3-piece silicone IOLs (1 monofocal backward, Allergan model SI-40NB; 1 multifocal in front, Allergan model SA-40N) were implanted in his left eye. At 8 days postoperatively, uncorrected visual acuity was 20/20 for distance and J1 for near vision in the right eye and 20/30 and J2, respectively, in the left. These values remained constant until the patient was seen 7 months postoperatively. Power calculation and insertion order of the piggyback IOLs were considered.- - - - - - - - - - ranking = 1keywords = near (Clic here for more details about this article) |
2/4. Exodeviation following monocular myopic regression after laser in situ keratomileusis.We report a 44-year-old woman with intermittent left exotropia of 35 prism diopters at distance who initially exhibited alignment of both eyes after bilateral laser in situ keratomileusis (LASIK). The exophoria was not preserved due to myopic regression in the dominant eye. An uneventful LASIK treatment was performed to correct -11.00 -0.50 x 130 in the right eye and -13.50 -1.50 x 145 in the left eye. The aim was to achieve emmetropia in both eyes. Although an examination revealed exophoria at near and distance during the 6 months following refractive surgery, the tropic aspect of the divergent deviation appeared in the right eye following the myopic regression. Laser in situ keratomileusis is an effective option to achieve binocular visual quality in myopic anisometropic patients. However, myopic regression after LASIK may disrupt the binocular visual quality.- - - - - - - - - - ranking = 1keywords = near (Clic here for more details about this article) |
3/4. The importance of base curve in the design of minus iseikonic lenses.PURPOSE: A widely advocated approach to increasing spectacle magnification in minus lenses is to increase center thickness and reduce vertex distance. Conventionally, a steeper base curve is to be avoided because of the accompanying increased vertex distance in a minus lens and the reduction of spectacle magnification that results. This approach works when small amounts of spectacle magnification are needed. However, when large amounts are needed for high minus lenses with flat base curves, the conventional approach does not provide sufficient magnification. Facial features such as eyelash length limit the contribution of reducing vertex distance, and the flat base curves limit the efficacy of increasing center thickness. Steeper base curves are required to increase the optical "leverage" of increasing center thickness. methods: Through use of an example, a steeper base curve is shown to increase the spectacle magnification of a high minus lens. The gain in spectacle magnification is preserved by maintaining a nearly constant vertex distance through bevel location. RESULTS: In the example, changing the base curve of a -6.50-D lens by 4.50 D while increasing the center thickness by 4.1 mm resulted in a 4.4% increase in spectacle magnification. The lens bevel was kept as close as possible to the front surface, allowing the increased center thickness to keep the back vertex at essentially a constant vertex distance in the presence of the steeper base curve. Without the steeper base curve, it was not possible to attain the needed spectacle magnification. CONCLUSIONS: When large amounts of spectacle magnification are needed for high minus lenses, both steeper base curves and increased center thicknesses are necessary. The reduction in spectacle magnification from increased vertex distance that is expected with steeper base curves can be neutralized by keeping the bevel close to the front surface on the thicker lens.- - - - - - - - - - ranking = 1keywords = near (Clic here for more details about this article) |
4/4. Induced hyperphoria in anisometropic presbyopia.anisometropia occurring either as a result of physiological or acquired etiologies may present a challenge to the optometrist if the patient is presbyopic. Fortunately, many patients with anisometropic presbyopia are able to adapt to near induced hyperphoria. There are, however, several options available for the optical management of symptomatic patients with near induced hyperphoria. These include: displacement of the distance optical centers, setting the bifocal segment higher than usual, using a combination of these two, dissimilar bifocal segments, slab-off prism and contact lenses. This paper reviews clinical considerations as well as the available spectacle management options.- - - - - - - - - - ranking = 2keywords = near (Clic here for more details about this article) |