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Modified bell retinoscopy: measuring accommodative lag in children
1Division of Ophthalmology, Childrens Hospital Los Angeles, Los Angeles, California 90027, USA. ktarczyhornoch@chla.usc.edu
Insights
Modified Bell Retinoscopy (MBR) effectively quantifies accommodative lag in children, showing good repeatability and comparability with other methods. This technique offers a valuable tool for assessing accommodation in young patients.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Vision Science
Background:
- Accurate assessment of accommodative lag is crucial for understanding visual development in children.
- Existing methods for measuring accommodative lag may have limitations in repeatability and comparability.
Purpose of the Study:
- To introduce and describe the Modified Bell Retinoscopy (MBR) method for quantifying accommodative lag in pediatric populations.
- To evaluate the repeatability and comparability of MBR with established techniques like Nott Retinoscopy (NR) and the Monocular Estimate Method (MEM).
Main Methods:
- MBR involves advancing a target until the retinoscopic reflex is neutralized, with lag estimated using a standardized 40-cm target.
- Repeatability was assessed within-visit and between-visit in normal children, clinic patients, and children with Down syndrome.
- Comparisons were made with NR and MEM in a subset of clinic patients.
Main Results:
- MBR demonstrated strong correlations with NR (r=0.84) and MEM (r=0.82).
- Repeatability varied with the amount of accommodative lag, with a repeatability index of 0.49 D for 0.50 D lag and 0.80 D for 1.00 D lag.
- Repeatability was consistent across different age groups and refractive errors, and similar in children with Down syndrome.
Conclusions:
- MBR provides reliable estimates of accommodative lag, correlating well with traditional dynamic retinoscopy measures.
- The method exhibits comparable repeatability to existing techniques, making it a potentially valuable clinical tool.
- MBR may enhance the assessment of accommodation in young children, aiding in early detection and management of visual issues.
Purpose:
To describe a modified bell retinoscopy (MBR) method for quantifying accommodative lag in children and to assess its repeatability and comparability with other techniques.
Methods:
In MBR, the target is advanced toward the patient until the retinoscopic reflex is neutralized. A "standardized 40-cm target estimate" of lag was derived for each child using data from three retinoscope distances. Within-visit repeatability was assessed in normal children 5 to 23 months of age, a heterogeneous group of clinic patients, and a group of children with Down syndrome. Clinic patients were tested on separate days for between-visit repeatability and, also, with Nott retinoscopy (NR) and the monocular estimate method (MEM) on day 2.
Results:
MBR correlated with NR (r = 0.84) and MEM (r = 0.82). MBR and NR estimates were lower than MEM for high lags. Within-visit repeatability of the standardized 40-cm target estimate of MBR in normal children and clinic patients varied with the amount of lag (p < 0.0001). The repeatability index for 0.50 D lag was 0.49 D and for 1.00 D lag it was 0.80 D. Repeatability was similar in children with Down syndrome. In clinic patients, the between-visit repeatability index for 0.50 D lag was 0.60 D for the second estimate of each day, with lower repeatability for the first measure of each day. Repeatability did not vary with age or refractive error. The decrease in repeatability with high lag may be attributable to spatial measurement error.
Conclusions:
MBR estimates of accommodative lag correlate with traditional dynamic retinoscopy measures over a wide range of lags and show comparable repeatability. MBR may be a useful addition to the repertoire of clinical tools available for assessing accommodation in young children.
