Optometrist, Lady Willington Hospital, Manali, Himachal Pradesh; Department of Ophthalmology, Christian Medical College, Vellore, Tamil Nadu, India.
Department of Ophthalmology, Christian Medical College, Vellore, Tamil Nadu, India.
Indian J Ophthalmol. 2021 Jul;69(7):1702-1706. doi: 10.4103/ijo.IJO_3160_20.
To study the relationship between the amplitude of accommodation (AA) measured by the Royal Air Force (RAF) rule and near addition (NA) prescribed in presbyopic patients to assess how far practice is different from theoretical recommendations.
Patients, aged 40 to 60 years with best corrected vision of 6/6 N5 were included in this cross sectional observational study. AA was measured using the RAF rule. Refined with near Duochrome chart, the NA was given with the chart at 40 cm. Accommodative reserve was calculated from the measured AA, NA required and the calculated additional accommodation expended by the patient for reading. The percentage of reserve was calculated with and without the correction for depth-of-field.
A total of 130 patients were studied. In the patients above 50 years of age, the negative correlation of AA with age was -0.298 (P = 0.065) and AA and NA was -0.365 (P = 0.002) was weak. Among the patients aged between 40 and 50 years, the negative correlation of AA with Age and NA were strong; -0.853 (P < 0.0001) and -0.823 (P < 0.0001) respectively. When prescribing glasses, 62.01% (CI 58.78 to 65.23) and 90.93% (CI 62.50 to 119.37) of the AA was found to be kept in reserve for patients below and above 50 years of age respectively.
Accommodative reserve kept in our study patients when prescribing NA was two to three times the theoretical recommendation. High percentage of accommodation kept in reserve suggest that the measured AA is not activated normally and require higher NA and one should not rely on patient's ability to generate accommodative power especially in patients over 50 years.
通过研究皇家空军（RAF）法则测量的调节幅度（AA）与远视附加（NA）之间的关系，评估实践与理论推荐之间的差异。
本横断面观察性研究纳入了年龄在 40 至 60 岁、最佳矫正视力为 6/6 N5 的患者。使用 RAF 法则测量 AA。使用近双色图表对其进行修正后，在 40cm 处使用图表给予 NA。从测量的 AA、患者为阅读而计算出的所需 NA 和额外调节力中计算调节储备。计算有和没有景深校正时的储备百分比。
共研究了 130 例患者。在 50 岁以上的患者中，AA 与年龄的负相关系数为-0.298（P=0.065），AA 与 NA 的负相关系数为-0.365（P=0.002），相关性较弱。在 40 至 50 岁的患者中，AA 与年龄和 NA 的负相关系数较强，分别为-0.853（P<0.0001）和-0.823（P<0.0001）。在为患者配眼镜时，发现 50 岁以下和 50 岁以上患者的 AA 储备分别为 62.01%（95%CI 58.78 至 65.23）和 90.93%（95%CI 62.50 至 119.37）。
本研究中，为患者开具 NA 处方时保留的调节储备是理论推荐值的两到三倍。高比例的调节储备表明，所测量的 AA 不能正常激活，需要更高的 NA，并且不应依赖患者产生调节力的能力，尤其是在 50 岁以上的患者中。
