Assessing the Relationship Between Accomodative Response and Varying Working Distance Using Dynamic Methods

Background: Two common dynamic clinical techniques used to quantify a patient’s accommodative response/posture are Nott retinoscopy and Monocular Estimation Method (MEM) retinoscopy. A standard test distance of 40 centimeters (cm) is utilized in both of these methods. However, outside of clinic, it is not uncommon for patients to hold their near work at distances other than 40 cm. This project will explore how other working distances affect the accommodative response. Methods: The design of this research project utilized Nott retinoscopy, MEM retinoscopy and the WAM-5500 auto-refractor for estimating accommodative response. Each technique was performed on the subject’s right eye at three different test distances: 25 cm, 40 cm, and 50 cm. Results: When evaluating the MEM method using a one-way analysis of variance (ANOVA), we determined that the accommodative lag differed between the three working distances (p = 0.0377). A one-way ANOVA was also performed on the Nott retinoscopy data with a corresponding p-value of 0.8700. The Nott method showed the working distance did not significantly change the accommodative lag measurement. Next, both methods were analyzed using two-way ANOVA. Together, the data did not show a statistically significant relationship between the change in working distance to accommodative posture with p= 0.06416. Conclusion: Based on the analysis of our data, we cannot conclude overall that the accommodative response changes with different working distances; however, our results did reveal that the answer may be dependent on which dynamic test is used. MEM retinoscopy showed that the working distance does in fact change how much a patient may under/over focus on a target. Conversely, Nott retinoscopy did not show a significant change in measurements with respect to the target distance. Therefore, when evaluating accommodative response at working distances other than 40 cm, the two methods cannot be used interchangeably.