近视眼在持续性近距离阅读时周边屈光状态的变化

Effect of sustained near reading on the relative peripheral refractive error in myopes

目的 研究近视者在持续性近距离工作状态下,近视眼周边屈光状态的变化及其变化规律,探讨其对近视发生、发展产生影响的可能机制.方法 25名近视志愿者参加本实验,年龄为23～33岁,平均年龄为（26.6±0.4）岁,等效球镜度数为-1.50～-6.50 D,平均为（-3.75±0.33）D,散光量〈0.75 D.用软性角膜接触镜对其双眼进行全矫,采用Grand Seilko WAM-5500红外自动验光仪,测量视远5 m和近注视33 cm调节状态下,以及33 cm注视距离下持续阅读45 min后右眼中心和颞侧30°的周边屈光度数20次,排除（均数±2×标准差）范围外的数据,然后取均值.屈光度数和周边屈光状态分别采用等效球镜和相对周边屈光度进行描述和分析.采用配对t检验和Pearson相关分析对测量结果进行统计学分析.结果 在视远状态时,人眼的相对周边屈光度为（0.99±0.66）D,呈现远视化状态;近注视调节状态时,周边屈光度为（0.73±0.61）D,远视化程度下降,较视远状态下差异无统计学意义（t=1.71,P=0.10）;持续性近距离阅读工作后,周边屈光度为（1.05±0.68）D,远视化程度更明显,较阅读前近注视状态时差异有统计学意义（t=-8.33,P=0.00）;近距离阅读前调节反应为（2.15±0.32）D,近距离阅读后略有上升至（2.19±0.33）D.但两者差异无统计学意义（t=1.43,P=0.17）.对持续近距离工作前、后的调节反应变化值与周边屈光状态变化值进行相关性分析,两者无显著相关性（r=-0.272,P=0.188）.结论 近视眼在持续近距离工作状态下周边屈光度数有显著变化,呈现暂时性的远视性漂移,比近距离工作前周边远视性离焦更大.由此推测,近视的发生及发展可能与持续性近距离阅读状态下周边屈光度数的变化（即周边显著离焦）有关.

Objective To investigate the changes in the relative peripheral refractive error （RPRE） of the human eye and its regularity under sustained near work conditions. Methods Twenty-five myopic subjects were enrolled, ranging in age from 22 to 33 years with an average age of （26.6±0.4）years. The spherical equivalent refractive error ranged from -1.50 D to -6.50 D, with an average of （-3.75±0.33）D, and astigmatism was less than 0.75 D. Soft contact lenses were used to correct refractive error for both eyes during the study. Autorefractive measurements at the fovea and at 30° eccentricity in the temporal retina at distances of 5 m, 33 cm, and 33 cm after 45 min of sustained reading at 33 cm were obtained using the spherical equivalent calculated with a Grand Seilko WAM-5500 autorefractor. Only the right eye of each subject was tested. Twenty readings were taken for each gaze condition and the mean value was used for analysis after excluding any values that were outside a certain range （mean±2SD）. Measurements of relative peripheral refractive error （RPRE） were analyzed by a paired samples t test and Pearson＇s correlation analysis. Results The RPRE was （0.99±0.66）D at a distance of 5 m as a baseline, indicating myopes displayed hyperopic shifts in the peripheral field and became less hyperopic with accommodation [（0.73±0.61）D], but there were no significant differences （t=1.71, P=0.10）. After 45 min of sustained reading at 33 cm, there was a hyperopic shift of （l.05±0.68）D, and there was a significant difference relative to pre-reading （t=-8.33, P=0.00）. The accommodative response for the pre-reading condition was （2.15±0.32）D, and increased to （2.19±0.33）D after 45 min of sustained reading at 33 cm, but there was no significant difference （t =1.43, P =0.17） and there was no correlation between the subject＇s change in accommodative response and the change in RPRE （r=-0.272, P=0.188）. Conclusion Sustained reading may have a significant effect on RPRE. There is an immediate hyperopic shift after sustained reading, indicating greater hyperopic defocus. The transient nature of these changes suggests that hyperopic defocus in the peripheral field may play a role in the relationship between sustained reading and myopia.