Continuous Objective Assessment of Near Work.

Area of Science:

• Ophthalmology
• Vision Science
• Biomedical Engineering

Background:

• Conflicting evidence exists on the role of near work in myopia development.
• Accurate measurement of near work duration and intensity is crucial for myopia research.
• Existing methods for assessing near work are often subjective and lack precision.

Purpose of the Study:

• To develop and validate the RangeLife device for continuous, objective measurement of working distance.
• To quantify near work using objective diopter hours (dh) and compare weekday vs. weekend behaviors.
• To assess the correlation between objective near work measures and subjective reports.

Main Methods:

• The RangeLife device was developed, calibrated, and validated for measuring viewing distance.
• Adult subjects simultaneously wore RangeLife and actigraph devices, maintaining activity logs.
• Objective diopter hours (dh) were calculated from RangeLife data, binned by viewing distance and light exposure.
• Subjective visual activity questionnaires were administered.

Main Results:

• Objective diopter hours (dh) were significantly higher on weekdays (14.73 ± 4.67 dh) compared to weekends (11.90 ± 4.84 dh, p=0.05).
• Most near/intermediate viewing occurred under indoor lighting (<1000 lux) and during sedentary activity.
• Subjective reports significantly overestimated objective near and intermediate viewing time (p=0.002).

Conclusions:

• The RangeLife device provides reliable, objective measures of viewing distance and near work.
• Weekday near work, measured objectively, is significantly higher than on weekends.
• This technology can advance understanding of how viewing behaviors influence refractive error and myopia progression.