Objective and subjective assessment of accommodative insufficiency.

SIGNIFICANCE: A variety of subjective and objective procedures are available to measure the amplitude of accommodation. However, it is unclear whether the standard criterion of Hofstetter's minimum minus 2 D can be used to diagnose accommodative insufficiency with each of these techniques. PURPOSE: The use of objective dynamic retinoscopy and three subjective techniques to diagnosis accommodative insufficiency was examined. METHODS: A total of 632 subjects between 8 and 19 years of age were enrolled. Accommodative lag, monocular accommodative facility, and subjective (push-up, modified push-down, and minus lens) and objective (dynamic retinoscopy) amplitude of accommodation were quantified. Accommodative insufficiency was diagnosed based on Hofstetter's minimum minus 2 D for each subjective method, as well as adding an additional subjective criterion (either accommodative lag exceeding 0.75 D or monocular accommodative facility falling below the age-expected norms). RESULTS: The prevalence of accommodative insufficiency was lowest and highest with the push-up (7.9 and 1%) and dynamic retinoscopy (94 and 12%) procedures when measured without and with the additional subjective criteria, respectively. Comparing the validity of dynamic retinoscopy against the traditional criterion, moderate to low sensitivity and high specificity were found. However, adding the additional subjective criteria improved the findings with moderate to high sensitivity and high specificity. Using a cutoff for dynamic retinoscopy of 7.50 D showed moderate diagnostic accuracy based on likelihood ratios. CONCLUSIONS: It is clear that a revised definition of accommodative insufficiency is required, which must include the method of assessing accommodation. The various objective and subjective methods for quantifying the amplitude of accommodation are not interchangeable, and subjective assessment does not provide a valid measure of the accommodative response.

A comparison of the reliability of dynamic retinoscopy and subjective measurements of amplitude of accommodation.

PURPOSE: Dynamic retinoscopy (DR) is an objective technique for assessing maximum accommodative responsivity. The present study examined the test-retest reliability of this procedure when measuring the amplitude of accommodation (AA). METHODS: In the first trial, the within-session repeatability of the AA was measured in 79 subjects between 18 and 30 years of age using DR and two subjective procedures, namely the modified push-down (MPD) and minus lens (ML) techniques. Data were collected by two different examiners. In a second trial, the inter-session repeatability of the AA was assessed in 76 subjects by a single evaluator with a time interval of 7 days between the first and second sessions. The repeatability, reproducibility and agreement between the methods were determined using the mean difference, 95% limits of agreement, intraclass correlation coefficient and concordance correlation coefficient. RESULTS: DR showed the lowest mean value of AA in each trial (average for the two trials = 7.44 D) while the equivalent mean values for the MPD and ML techniques were 9.84 and 9.43 D, respectively. Further, DR showed the best repeatability in both the repeatability trials and poorer inter-examiner agreement was observed for the MPD and ML procedures. The concordance correlation coefficient for DR-MPD, DR-ML and MPD-ML procedures were 0.32, 0.33 and 0.62, respectively for the within-session trial and 0.31, 0.36 and 0.76, respectively for the inter-session trial. CONCLUSION: The DR technique provides a more veridical measurement of the AA because it avoids the overestimation resulting from the depth-of-field. Moreover, the DR technique exhibited higher reproducibility, when compared with subjective methods. These differences may be important when evaluating accommodative dysfunctions or monitoring accommodative therapy. The fact that the DR procedure can be performed using standard clinical equipment makes this a valuable technique both for vision screening programs and routine eye care.