Altoaimi Basal H, Almutairi Meznah S, Kollbaum Pete S, Bradley Arthur
School of Optometry, Indiana University, Bloomington, Indiana.
Department of Optometry, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia *
Optom Vis Sci. 2018 May;95(5):416-427. doi: 10.1097/OPX.0000000000001214.
The effectiveness of multifocal contact lenses (MFCLs) at slowing myopia progression may hinge on the accommodative behavior of young eyes fit with these presbyopic style lenses. Can they remove hyperopic defocus? Convergence accommodation as well as pupil size and the zonal geometry are likely to contribute to the final accommodative responses.
The aim of this study was to examine the accommodation behavior of young adult eyes wearing MFCLs and the effectiveness of these MFCLs at removing foveal hyperopic defocus when viewing near targets binocularly.
Using a high-resolution Shack-Hartmann aberrometer, accommodation and pupil behavior of eight young adults (27.25 ± 2.05 years) were measured while subjects fixated a 20/40 character positioned between 2 m and 20 cm (0.50 to 5.00 diopters [D]) in 0.25-D steps. Refractive states were measured while viewing binocularly and monocularly with single-vision and both center-distance and center-near +2.00 D add MFCLs. Refractive state was defined using three criteria: the dioptric power that would (1) minimize the root mean square wavefront error, (2) focus the pupil center, and (3) provide the peak image quality.
Refractive state pupil maps reveal the complex optics that exist in eyes wearing MFCLs. Reduced accommodative gain beyond the far point of the near add revealed that young subjects used the added plus power to help focus near targets. During accommodation to stimuli closer than the far point generated by the add power, a midperipheral region of the pupil was approximately focused, resulting in the smallest accommodative errors for the minimum root mean square-defined measures of refractive state. Paraxial images were always hyperopically or myopically defocused in eyes viewing binocularly with center-distance or center-near MFCLs, respectively. Because of zone geometry in the concentric MFCLs tested, the highly aberrated transition zone between the distance and near optics contributed a significant proportion and sometimes the majority of light to the resulting images.
Young eyes fit with MFCLs containing significant transition zones accommodated to focus pupil regions between the near and distance optics, which resulted in less than optimal retinal image quality and myopic or hyperopic defocus in either the pupil center or pupil margins.
多焦点隐形眼镜（MFCL）减缓近视进展的有效性可能取决于佩戴这类老花镜样式镜片的年轻眼睛的调节行为。它们能消除远视性离焦吗？集合性调节以及瞳孔大小和区域几何形状可能会影响最终的调节反应。
本研究旨在检查佩戴MFCL的年轻成年人眼睛的调节行为，以及这些MFCL在双眼观察近目标时消除中央凹远视性离焦的有效性。
使用高分辨率的夏克-哈特曼像差仪，测量了8名年轻成年人（27.25±2.05岁）的调节和瞳孔行为，受试者注视一个位于2米至20厘米（0.50至5.00屈光度[D]）之间、以0.25 D步长变化的20/40字符。在双眼和单眼观察时，分别使用单焦点镜片以及中心距离和中心近用+2.00 D附加的MFCL测量屈光状态。屈光状态使用三个标准定义：（1）使均方根波前误差最小化的屈光度，（2）使瞳孔中心聚焦的屈光度，（3）提供最佳图像质量的屈光度。
屈光状态瞳孔图揭示了佩戴MFCL的眼睛中存在的复杂光学现象。在近附加光度的远点之外，调节增益降低表明年轻受试者利用增加的正度数来帮助聚焦近目标。在调节到比附加光度产生的远点更近的刺激时，瞳孔的中周区域大致聚焦，从而使屈光状态的均方根定义的最小测量值的调节误差最小。在分别使用中心距离或中心近用MFCL双眼观察时，近轴图像在眼睛中总是远视性或近视性离焦。由于所测试的同心MFCL中的区域几何形状，远用和近用光学区域之间高度像差的过渡区域对最终图像贡献了很大比例的光，有时甚至是大部分光。
佩戴含有明显过渡区域的MFCL的年轻眼睛会进行调节，以使瞳孔区域聚焦在近用和远用光学区域之间，这导致视网膜图像质量低于最佳水平，并且在瞳孔中心或瞳孔边缘出现近视性或远视性离焦。
