Ophthalmology clinics of North America最新文献

The NuLens intraocular lens (IOL) uses a new optomechanical concept to generate a wide range of dioptric power from minimal movements of the ciliary apparatus during accommodative effort. Basic study of the concept of optomechanics in the primate eye led to successful construction and implantation of functioning IOL prototypes.

Presbyopia (literally, "old eye"), the age-related loss of the ability to accommodate, is the most common ocular affliction in the world. Although the lens no doubt has a major role in presbyopia, altered lens function could be in part secondary to extralenticular age-related changes, such as loss of ciliary body forward movement. Centripetal ciliary muscle movement does not seem to decrease significantly with age. Loss of elasticity of the ciliary muscle posterior attachments may be an important factor contributing to presbyopia. Even if loss of ciliary muscle mobility is not causally related to presbyopia, it may limit the performance of putatively accommodating intraocular lenses now being developed by academic and industrial groups.

Currently, two single optic accommodative intraocular lenses are available for implantation. Both designs rely on the interaction of the ciliary muscle with the zonule and capsule to induce axial movement of the optic. This article reviews the historical development, laboratory data, and clinical findings relating to these interesting devices.

If presbyopia is caused by hardening of the crystalline lens, replacing it with a material with mechanical properties similar to the young crystalline lens should restore accommodative ability. Such a silicone material has been developed. Refilling the capsular bag with this material results in 3 to 5 D of accommodation in primates in response to pilocarpine.

A clear understanding of the anatomy of accommodative structures, the mechanism of accommodation, and the causes of presbyopia is necessary to understand whether accommodation may be restored to the presbyopic eye. Not withstanding the significant challenges that are faced owing to age-related changes in the eye, theoretically, it may be possible to restore accommodation to a presbyopic eye with an artificial accommodative intraocular lens.

Today, many options are available for the correction of presbyopia. New technology perpetually surfaces to offer better ideas and designs to meet the visual demands of the presbyopic population. This article provides information on various modalities for spectacle and contact lens correction of presbyopia. It is based on current information at the time of publication and is not intended to be a fitting guide.

This article reviews the advantages and disadvantages of various techniques used to achieve monovision, with an emphasis placed on monovision with laser vision correction.

The Sarfarazi accommodative intraocular lens, currently in clinical studies, is a single continuous silicon accommodative lens with dual optics and three haptics that mimic the action of the natural lens by using the contraction and relaxation of ciliary muscles. The lenses have been implanted in the eyes of patients. There have been no surgical or patient complications related to the lens, and its safety has been clearly demonstrated. Patient acceptance of the lens is excellent. Clinical enrollment will continue to expand.

This article compares methods of axial length measurement for determining intraocular lens power and describes bimanual micro incision phacoemulsification for refractive lens exchange and routine cataract surgery, which offers an enormous advantage of maintaining a more stable intraocular environment during lens removal. This advantage may be especially important in high myopes who are at a greater risk for retinal detachment following lens extraction.

The ability to diagnose and treat dry eye has improved dramatically over the last decade as understanding of disease mechanisms and pathology has improved. The ability to screen patients for dry eye before ophthalmic plastics procedures has improved, and the ability to manage and treat dry eye in patients after surgery also has improved.