Objective and subjective measurement of tonic accommodation.

Measurements of tonic accommodation (TA) were made on 25 subjects using He-Ne laser optometry (HNL), infra-red optometry (IR) and near retinoscopy (NR) under darkroom conditions. All three techniques were shown to produce comparable mean estimates of TA (HNL: 1.10 D; IR: 1.15 D; NR: 1.07 D). Significant correlations were found between HNL and IR (r = 0.88, p less than 0.001) and between HNL and NR (r = 0.81. p less than 0.001). Control studies under cycloplegia indicate that the estimates are not seriously affected by fluctuations in accommodative state. These findings indicate that ophthalmic practitioners can gain access to refractive data that aids the clinical management of the "anomalous myopias" and asthenopia associated with VDU work.