Bifocal Profiles and Strategies of PresbyLASIK for Pseudoaccommodation

Developments in the correction of presbyopia II: surgical approaches

PURPOSE

To discuss the various static and dynamic surgical approaches which attempt to give presbyopes good vision at far, intermediate and near viewing distances.

CONTENT

Static methods broadly adopt the same optical techniques as those used in presbyopic contact lens correction and aim to satisfy the needs of the presbyope by increasing binocular depth-of-focus, often using monovision as well as simultaneous-imagery. Dynamic methods generally attempt to make use of at least some of the still-active elements of the accommodation system. They include procedures which are supposed to modify the relative geometry of the ciliary muscle and lens, or which reduce the stiffness of the presbyopic lens either by replacing it with other natural or man-made material or by subjecting it to femtosecond laser treatment. Alternatively the natural lens may be replaced by some form of intraocular lens which changes power as a result of forces derived from the still-active ciliary muscle, zonule and capsule, or other sources.

CONCLUSIONS

At present, multifocal intraocular lenses appear to offer the most consistent and reliable surgical approach to surgical presbyopic correction. They have obvious advantages in convenience and stability over optically-similar, simultaneous-image presbyopic contact lenses but this must be balanced against their relative inflexibility in cases of patient dissatisfaction. Dynamic methods remain largely experimental. Although some approaches show promise, as yet no method has demonstrated a reliable, long-term ability to correct distance refractive error and to appropriately change ocular power in response to changes in viewing distance over the normal range of interest.

Aspheric wavefront-guided LASIK to treat hyperopic presbyopia: 12-month results with the VISX platform

PURPOSE

To evaluate an aspheric ablation profile to improve near vision in presbyopic patients with hyperopia and to outline the key factors of success.

METHODS

A prospective, nonrandomized, clinical trial of 66 eyes of 33 hyperopic patients who underwent customized bilateral refractive surgery, which included an aspheric presbyopia treatment shape and wavefront-driven hyperopic treatment, was studied. Surgeries were performed using the VISX STAR S4 or STAR S4 IR excimer laser system (Abbott Medical Optics). Mean preoperative refractive error was +1.77 ± 0.56 diopters (D) sphere (range: 0.75 to 3.50 D) with 0.41 ± 0.34 D cylinder (range: 0.00 to 1.50 D). All patients received full distance refractive correction. No patients received monovision or were intentionally left with residual myopia. Patient satisfaction results were evaluated using a questionnaire with a 5-point scale.

RESULTS

Sixty eyes completed 6-month and 50 eyes completed 12-month postoperative follow-up. At 6 months, mean corrected distance visual acuity (CDVA) was 20/20±1 line (range: 20/25 to 20/10). Mean gain in distance-corrected near visual acuity (DCNVA) was 2.7 ± 1.7 lines with a maximum of 6 lines of near. Spectacle dependence for tasks, such as reading and computer use, was reduced. At 12 months, 100% of patients had achieved binocular simultaneous uncorrected vision of 20/25 or better and J3. Refraction was stable over 12 months. Contrast sensitivity reduction was clinically insignificant (1 step or 0.15 logCS). Negative spherical aberration highly correlated with postoperative improvement of DCNVA. Patients who had a larger amount of preoperative hyperopia or a greater decrease of preoperative DCNVA were more likely to have overall satisfaction.

CONCLUSIONS

The aspheric ablation designed to expand near functional vision was effective and stable over 12 months. The wavefront-customized hyperopic treatment significantly reduced spectacle dependence.

Multifocal corneal ablation for hyperopic presbyopes

PURPOSE

To investigate the clinical results of multifocal wavefront-guided corneal ablation with a central near zone in hyperopic presbyopes.

METHODS

Twenty-seven patients (54 eyes) were analyzed retrospectively. Monocular near and distance uncorrected visual acuity (UCVA) and binocular near and distance UCVA were measured preoperatively, and the near addition power and the manifest refraction were obtained. Measurements of spherical aberration, coma, total higher order aberration, and contrast sensitivity for high and low photopic conditions were performed. All patients received multifocal corneal ablations with a central near zone using the VISX CustomVue System and were examined at 1 month (48 eyes), 2 months (42 eyes), and 6 months (28 eyes) after surgery.

RESULTS

Of 14 patients, 9 (64.3%) achieved both 0.8 or better in binocular distance UCVA and 0.65 or better in binocular near UCVA, and the spherical equivalent refraction and near addition power decreased from +1.16+/-0.82 diopters (D) to +0.33+/-0.45 D and from 2.35+/-0.44 D to 1.42+/-0.62 D at 6 months after surgery, respectively. No significant changes were noted in total higher order aberration and contrast sensitivity, whereas spherical aberration coefficients (Z-12) changed from positive to negative.

CONCLUSIONS

Multifocal wavefront-guided refractive surgery in presbyopia offered effective correction in hypermetropia and satisfactory near vision without significant increase in comeal total higher order aberration or significant decrease in contrast sensitivity.