Carney L G
College of Optometry, Ohio State University, Columbus 43210.
Cornea. 1990;9 Suppl 1:S16-9; discussion S23-4. doi: 10.1097/00003226-199010001-00008.
Two factors govern the quality of vision with contact lenses (CLs): the fit and movement of the lens and the adequacy of its optics. Studies have not demonstrated any inherent inadequacies in material or design parameters that might account for visual difficulties in lens wearers. To the contrary, thickness, water content, and fit can be varied within clinically acceptable ranges without compromising vision. A poorly fitted lens, however, can cause excessive corneal edema and consequent visual problems. Poor vision may also result from uncorrected refractive error, the development of an unstable optical surface, or the use of a lens material that is inherently inadequate for a given patient. Such causes of visual dysfunction can usually be avoided through better fitting, better lens care, more careful refraction, or better patient-lens matching. Specialized lens designs can sometimes be used to correct vision problems. Certain types of rigid front-surface aspheric lenses, for example, provide astigmats with even better visual correction than spherical rigid lenses or spectacles, but the improvement is small and highly patient dependent. Similarly, although soft toric lenses can provide good vision, it is often technically difficult to orient and stabilize the correcting cylinder.
有两个因素决定了隐形眼镜（CL）的视力质量：镜片的适配度和移动性以及其光学性能的充分性。研究尚未证明材料或设计参数存在任何内在不足，这些不足可能导致佩戴者出现视力问题。相反，在临床可接受的范围内改变厚度、含水量和适配度不会影响视力。然而，适配不良的镜片会导致角膜过度水肿，进而引发视力问题。视力不佳也可能是由于未矫正的屈光不正、不稳定光学表面的形成，或使用了对特定患者来说本质上不合适的镜片材料。通常可以通过更好的配镜、更好的镜片护理、更仔细的验光或更好的患者与镜片匹配来避免这些导致视觉功能障碍的原因。有时可以使用专门的镜片设计来矫正视力问题。例如，某些类型的刚性前表面非球面镜片为散光患者提供的视力矫正效果甚至比球面刚性镜片或眼镜更好，但改善效果很小且高度依赖患者个体。同样，尽管软性散光镜片可以提供良好的视力，但在技术上往往难以定位和稳定矫正柱镜。
