Depth of Focus: Clinical Manifestation

Abstract

Purpose

To assess depth of focus on the basis of measurements of the point spread function, which involve Stiles and Crawford phenomenon.

Setting

Department of Ophthalmology of National Academy of Postgraduate Education.

Methods

Gullstrand's schematic eye parameters and data of subjective measurement of size of diffusion circles were used for calculation of depth of focus. Data of 1171 eyes with visual acuity 1.0–2.0 were included in the study.

Results

Under condition of visual acuity 1.5 data of the depth of focus were 0.38 D, 0.64 D, and 1.92 D for pupil diameter 5.0 mm, 3.0 mm, and 1.0 mm, respectively. Visual acuity 1.0 is characterized by larger value and visual acuity 2.0 by lesser value of the depth of focus.

Conclusions

Depth of focus and normal levels of visual acuity have a close relation: the higher the visual acuity, the smaller the depth of focus.