多灶性隐形眼镜磨损中的住宿训练

There’s a building volume of research that multifocal soft contact lens (MFCL) wear in non-presbyopes reduces the accommodative response (increase accommodative lag).(1, 2) Centre-distance MFCLs have been investigated in this respect as these have been similarly investigated for myopia control.(3) The potential mechanism for this reduced accommodative response is that the young eye, with large pupils, experiences a significant percentage of the pupil area covered by the ‘add’ zone in combination with the central, myopia correcting distance zone. Optical modelling has indicated that smaller central optic zone diameters (OZDs) could be associated with a reduced accommodative response, as the young eye uses the ‘add’ at near instead of accommodating. Larger OZDs may encourage a more normal accommodative response. This is important as a reduced accommodative response – using the ‘add’ zone at near – could then lead to the distance portion of the MFCL to generate hyperopic defocus, which is presumably deleterious in achieving myopia control.(4) By contrast, if an eye is accommodating normally at near through the central distance zone, the peripheral ‘add’ zones will create relative myopic defocus, which is presumed to create a ‘slow down’ signal for eye growth.(5)

直到最近，该建模才通过实验确认，并且该领域还很年轻。Orthokeratology (OK), which creates a ‘centre-distance, peripheral-add’ optical profile similar to MFCLs(6, 7) has been shown to reduce accommodative lag in myopic children and young adults compared to single vision distance contact lenses.(8) One study has correlated a below average amplitude of accommodation in myopic children at baseline with a larger increase in amps when wearing OK, and a better myopia control effect.(9) When it comes to MFCL, a novel lens design employing positive spherical aberration (effectively a centre-distance design) demonstrated that the test lens reduced accommodative response, and this reduced response was correlated with a reduced myopia control effect. Interestingly, this relationship wasn’t found in the single vision distance CL corrected control group,(10) indicating a complex interaction between MFCL optics and accommodation specifically.

In this study, the authors found a reduced accommodative response in MFCL wearing young myopes, in agreement with previous authors. They tested CooperVision Biofinity centre-distance MFCls with a +2.50 Add, in comparison to habitual single vision distance (SVD) CL wear and spectacle trial lenses, also SVD. At 40cm, the MFCL lag was 0.50-0.75D more than spec or CL SVD lag; and at 25cm the MFCL lag was over 1D greater than SVD CLs. They undertook auditory biofeedback for 200 seconds where a tone was sounded for the current level of response of the right eye, along with a second tone denoting the demand. When response matched demand, the tones matched and accommodation was accurate. The aim of biofeedback is to facilitate conscious control of a physical function which normally takes place unconsciously, and has been used previously in ophthalmological studies in the 1980s and 1990s to attempt to relax accommodation. In this study, the participants were asked to increase their accommodation response - improve their accuracy - until the pitches of both tones matched. After a two minute break, accommodation response was measured again, without the auditory feedback. Responders were defined as where the accommodative lag reduced by 0.3D or more.

训练效果总体较小，大多数校正刺激距离条件的改善小于0.1d的可容纳滞后。响应式参与者是SVD奇观（试验镜）佩戴者的47％；63％的SVD CL佩戴者和42％的MFCL佩戴者。反应灵敏的参与者在SVD校正的基线时具有更大的适应性滞后趋势，但是MFCL佩戴者没有这种关系。得出的结论是，尽管这种听觉生物反馈训练确实改善了住宿响应，但在MFCL佩戴者中的可预测性和可延展性较低，也许是因为MFCL的“添加”区域产生了矛盾的信号，以改变（减少）住宿响应。作者推测是否可以将更长的培训期和重复的训练期应用于佩戴MFCL的儿童以增加适应性反应，以及这是否会提高近视控制功效。

This research points to the value of assessing accommodation in young myopes. A normal accommodative response is important for visual comfort - accommodative lags over 1D have been correlated with contact lens discomfort symptoms in young adult myopes.(11) A normal accommodative response seems to be increasingly valuable in achieving myopia control efficacy. The findings here add to the picture of MFCLs reducing accommodative response – this may be significant for some myopes in terms of their visual comfort and myopia control results, while it may be inconsequential for others. As we learn more about the interaction between MFCL and accommodation, it may be in future that we select a particular type of MFCL for particular myopes based on their accommodation, and/or we seek to improve accommodative responses through specific corrections or training to optimize myopia control efficacy.