Carkeet Andrew
Department of Optometry and Vision Science, The University of Auckland, New Zealand or Optometry Centre CPB, Singapore Polytechnic, 500 Dover Rd, Singapore 139651.
Clin Exp Optom. 1998 Jul-Aug;81(4):151-158. doi: 10.1111/j.1444-0938.1998.tb06773.x.
Some previous researchers have shown empirically that visual fields can be restricted by contact lenses with opaque and semi-opaque peripheral zones. However, there has been no formal statement of the optical theory behind such restriction. METHODS: Calculations are made of fields of view with opaque periphery contact lenses, based on paraxial theory and meridional finite ray tracing in the Gullstrand-Emsley schematic eye. RESULTS: This analysis shows that paraxial theory is adequate for predicting 'half fields of full illumination' for ocular pupil diameters smaller than six millimetres, although paraxial estimates of 'half total field' can substantially underestimate those obtained by finite ray tracing for a wide range of ocular pupil sizes. Therefore finite ray tracing may be a more appropriate method of calculating half total field. 'Total field' will be smaller with smaller ocular pupils and smaller contact lens apertures. A clinical method is suggested for assessing total field with such contact lenses in situ. The analysis applied to opaque periphery contact lenses is extended to the semi-opaque periphery contact lenses used for cosmetic alteration of eye appearance. CONCLUSION: Semi-opaque periphery contact lenses will decrease retinal illuminance most at regions outside those tested by previous empirical static perimetry studies.
先前一些研究人员通过实验表明，具有不透明和半透明周边区域的隐形眼镜会限制视野。然而，对于这种限制背后的光学理论尚无正式阐述。方法：基于近轴理论和在Gullstrand - Emsley简化眼模型中的子午有限光线追迹，对带有不透明周边的隐形眼镜的视野进行计算。结果：该分析表明，对于眼瞳直径小于6毫米的情况，近轴理论足以预测“全照明半视野”，尽管对于各种眼瞳尺寸，近轴理论对“半总视野”的估计可能会大大低估通过有限光线追迹获得的结果。因此，有限光线追迹可能是计算半总视野更合适的方法。眼瞳越小且隐形眼镜孔径越小，“总视野”就越小。本文提出了一种在原位评估此类隐形眼镜总视野的临床方法。将应用于不透明周边隐形眼镜的分析扩展到用于眼部外观美容改变的半透明周边隐形眼镜。结论：半透明周边隐形眼镜在先前经验性静态视野检查研究未测试的区域会使视网膜照度降低最多。
