Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ACCOMMODATION (OCULAR)”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,477 records · Page 82Linked to original sources
PubMed2000

Nearwork and myopia.

Explore the source record for details and available documents.

Accommodation, Ocular↗
PubMed1981

Planned myopic astigmatism as a substitute for accommodation in pseudophakia.

Patients with an implanted intraocular lens can be made nearly spectacle independent by increasing the depth of focus of the uncorrected implanted eye. In simple myopic astigmatism the visual acuity can be above 20/50 from far to near because the size of the blurred retinal image changes less than its shape as an object approaches the eye. For simple myopic astigmatism the change in corneal power must be included in the calculation of intraocular lens power. The change in corneal power induced by surgery is a spherocylinder with no spherical equivalent. The postoperative shape of the cornea can be predicted and intraocular lens power is calculated to make the flatter meridian emmetropic. The stronger meridian of the cornea is then myopic. In a series of 40 successive cases, the refractions and the measured depth of focus illustrate the application of these principles and the advantage of myopic astigmatism for the pseudophakic patient.

Accommodation, Ocular↗
PubMed1983

Iseikonia and accommodation in the fellow eye in monocular IOL implantation.

In unilateral implantation of an intraocular lens (IOL), the main goal, for both distant and near vision, is iseikonia. After monocular IOL implantation, when the normal fellow eye accommodates for different distances, the changed magnification will result in aniseikonia. We have derived formulas for calculating the power of an iseikonizing IOL and of corresponding spectacles for both distant and near vision. Using the formulas, we can predict the degree of aniseikonia produced by accommodation in the normal eye. We suggest that accommodation in the fellow eye be avoided by using reading glasses.

Accommodation, Ocular↗
PubMed2001

Understanding refraction and accommodation through "retinal imaging" aberrometry: a case report.

PURPOSE: A new form of aberrometry based on Tscherning optics has been proposed that captures the refraction and high-order aberrations of the eye with and without accommodation. DESIGN: Experimental clinical optics study. METHOD: A green neodymium:yttrium-aluminum-garnet laser grid pattern is projected into the eye and viewed on the retina through a narrow, collimated aperture of 1 mm. The resulting aberrated pattern is photographically recorded in a normal eye in the unaccommodated and accommodated state through a pharmacologically dilated pupil without cycloplegia. MAIN OUTCOME MEASURES: Detection of pupil-dependent refraction and high-order optical aberration with and without accommodation. RESULTS: Subtle pupil-dependent errors in refraction and high-order aberrations (spherical aberrations and coma) are demonstrated in the unaccommodated normal eye. Accommodation reveals slightly more spherical power through the central 3-mm zone than through a 6.5-mm pupil without significant increase in aberration. CONCLUSIONS: Tscherning aberrometry based on 'retinal imaging' is useful in defining the refraction and optical aberrations in a normal eye. Accommodation increases spherical refractive power with only small aberration changes, including negative asphericity.

Accommodation, Ocular↗
PubMed2001

Scleral expansion bands for presbyopia.

OBJECTIVE: To evaluate the safety and effectiveness of surgery using scleral expansion bands. DESIGN: Prospective, noncomparative, small case series. PARTICIPANTS: Six subjects were enrolled. Four subjects received implants in one eye and two subjects received implants in both eyes. METHODS: Implantation of the scleral expansion bands (SEB) was performed using Schachar's standard technique. Subjects were observed at six postoperative examination intervals through 1 year. MAIN OUTCOME MEASURES: The key efficacy measures were distance-corrected near visual acuity (at 40 cm and 60 cm) and subjective amplitude of accommodation (push-up, push-down, and minus lens procedures). RESULTS: Distance visual acuity was similar before and after surgery. The near visual acuity and the subjective amplitude of accommodation were temporarily improved in three eyes. However, in the other five eyes, we did not note any improvement of accommodation or near vision after the scleral expansion surgery. CONCLUSIONS: In this study, the outcome of the SEB intervention was characterized by inconsistent and unpredictable results with a low level of patient satisfaction.

Accommodation, Ocular↗
PubMed2001

Presbyopia, accommodation, and the mature catenary.

OBJECTIVE: To demonstrate a plausible explanation of aging changes and to reduce the controversy relative to accommodation by using a mechanical model of the catenary theory of lens change. MECHANICAL MODELING: A mechanical model was used to simulate a human lens in both the accommodated and unaccommodated state to demonstrate changes in the mechanism of accommodation with age. METHODS: Fluid-filled latex balloons were supported by a plastic wrap hammock to form a catenary that models the human lens. Increasing volumes were used to simulate that of the aging lens, and variations in curvature were measured. MAIN OUTCOME MEASURES: The degree of curvature of a simulated anterior lens surface was measured and compared with mathematical modeling of its optical surface based on the catenary hydraulic suspension theory. RESULTS: The measurements showed that accommodative loss and other features such as mass displacement, reproducible lens surfaces, and zonule support are consistent with the catenary theory of accommodation and an increasing lens volume with age. CONCLUSIONS: The catenary theory of accommodation provides a basis for evaluating age changes of the human lens. Variable results with surgical procedures for presbyopia are also predictable with the model. These results can be used to provide a basis for intraocular lens design.

Accommodation, Ocular↗
PubMed2001

Clinical evaluation of the model AT-45 silicone accommodating intraocular lens: results of feasibility and the initial phase of a Food and Drug Administration clinical trial.

OBJECTIVE: To evaluate the clinical outcomes in cataract patients after implantation of an accommodating intraocular lens, designed to move forward and backward along the visual axis. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: Sixty-two patients scheduled for small-incision, extracapsular cataract extraction by phacoemulsification. METHODS: Twenty-eight eyes of 14 patients in the feasibility phase of the study and 48 eyes of 48 patients in the next phase of study underwent cataract extraction and implantation of the AT-45 accommodating intraocular lens. Prospective follow-up was analyzed at 1 month after surgery and compared with baseline characteristics 1 month and 3 to 6 months after surgery. MAIN OUTCOME MEASURES: Postoperative distance (uncorrected and best corrected), near (uncorrected, through the distance correction, best-corrected, i.e., with add), and intermediate (through the distance correction) visual acuity. RESULTS: All patients with monocular pseudophakia had best-corrected distance visual acuity of 20/40 or better. Patients with bilateral pseudophakia had best-corrected visual acuity of 20/25 or better when tested binocularly. The results from 28 eyes of 14 patients participating in the feasibility study were combined with those from 48 eyes of 48 patients included in the next phase of the AT-45 study. Uncorrected distance visual acuity was 20/40 or better in most patients (90%, or 56 of 62 eyes implanted and available for follow-up). Ninety-seven percent of patients (60/62) had uncorrected near visual acuity of 20/30 or better. Forty-eight eyes had intermediate visual acuity measured at 28 inches without 'add', and 44 of them (92%) achieved 20/30 or better. No complications or adverse events were reported. CONCLUSIONS: The AT-45 accommodating intraocular lens, designed to allow movement along the visual axis of the eye by using the natural physiology of the intact ciliary muscle after cataract removal, provides patients with excellent uncorrected distance, intermediate, and near visual acuity and should be considered as a modality to allow the majority of pseudophakic patients to see at all distances without glasses.

Accommodation, Ocular↗
PubMed2001

Experimental increase in accommodative potential after neodymium: yttrium-aluminum-garnet laser photodisruption of paired cadaver lenses.

PURPOSE: Loss of lens elasticity is one of several proposed mechanisms responsible for the decline in accommodation with age and is the most accepted explanation for presbyopia. We wish to confirm the lens elasticity premise and attempt to experimentally reverse the age-dependent loss of accommodative potential as measured by polar strain. DESIGN: Experimental human autopsy eye study. PARTICIPANTS AND CONTROLS: Thirty-six cadaver lenses were tested to determine the age-dependent polar strain. Eleven lens pairs were then tested with one lens treated with neodymium:yttrium-aluminum-garnet (Nd:YAG) laser and the other left untreated before rotation as an age control. TESTING: Using a custom-made rotational apparatus (described by Fisher, 1971), freshly excised cadaver lenses (<48 hours postmortem) were rotated at 1000 rpm on a 9-mm diameter pedestal to simulate the physiologic pull of the zonules. Lenses were initially tested to determine the age-dependent polar strain. One lens in a pair was then treated with an Nd:YAG laser and the other left untreated before testing. Treatment consisted of 100 suprathreshold pulse placed in a central annular pattern of 2- to 4-mm diameter. Treatment energies varied from 2.5 to 7.0 mJ/pulse, depending on the relative clarity of the lenses. Polar strain was both microscopically measured and calculated from projected photographs before and after rotation of both lased and unlased lenses. Statistically significant differences were determined by paired t test. MAIN OUTCOME MEASURES: Polar strain (decrease in axial thickness with rotation) of the lens. RESULTS: An age-dependent decrease in polar strain was observed that paralleled the findings of Fisher. Both measured and projected polar strain were greater in the lased than unlased lens, and this difference was highly significant by paired t test (P = 0.001 and P = 0.004, respectively). CONCLUSIONS: Age-dependent loss of lens elasticity (polar strain) can be experimentally reversed (increased) by selective intralenticular photodisruption.

Accommodation, Ocular↗