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Nicola Szostek, Hetal Buckhurst, Christine Purslow, Avril Collinson, Phillip J Buckhurst; Relationship between the subjective measurement of accommodative facility and the objective assessment of the dynamic accommodative response. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):6008.
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© ARVO (1962-2015); The Authors (2016-present)
The dynamic accommodative response can be assessed objectively using a modified open field autorefractor. Previous studies have utilised the results of autorefraction to describe accommodative latency and lag. Accommodative facility is a subjective method, used in clinical practice for the assessment of the speed of accommodative change. This study proposes new metrics for assessing accommodative dynamics and relates these metrics to the measurement of accommodative facility.
Accommodative dynamics were measured using the Grand Seiko WAM 5500 autorefractor (RyuSyo, Japan) on 42 healthy adults (mean 30±8yrs, range 19-47yrs). A 4.00D accommodative stimulus was presented in 5-second cycles using the DynaWAM Badal adaption. A 4-parameter sigmoidal regression curve function was fitted to each data set and used to determine: time taken to full accommodation (SoA) and disaccomodation (SoD), latency of accommodation (LoA) and disaccommodation (LoD). The total objective speed of accommodative change (oSoAC) was defined as the sum of SoA and SoD. In addition LoA was calculated again using a data smoothing method used in previous studies (sLoA). Accommodative facility (AF) with a 4.00D stimulus change was assessed via the number of cycles achieved per minute (CPM). Spearman’s Rho test was conducted to examine the correlation between accommodative dynamics metrics, AF and age.
The mean SoA: 2.45s±1.32; SoD: 1.88s±0.56; AF: 11.5±6.5; oSoAC: 4.36s±1.42; LoD: 1.04s±0.50; LoA: 1.17s±0.4; and sLoA: 0.93s±0.41. The age of the subject was found to correlate with the measures of SoA (r=0.339, p<0.028), SoD (r=0.415, p<0.06), AF (r=-0.611, p<0.001), and total oSoAC (r=0.661, p<0.001). However, neither metric for determining accommodative latency correlated with age (p>0.05). AF showed a significant, inverse correlation with SoD (r =-0.454, p<0.03), LoD (r =-0.325, p <0.36) and oSoAC (r =-0.390, p <0.11) but failed to show any significant association with SoA and both measures of accommodative latency (p>0.05).
The traditional assessment of accommodative latency via accommodative dynamics did not correlate with age or AF. The novel metrics of SoD, LoD and SoAC proposed in this study correlated with both AF and age and may provide additional insight into accommodative dynamics that relate to clinical measurements and patient symptoms.
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