Session: Poster session A

Depth perception and intraocular differences in older spectacle wearers

Introduction: To explore the clinical relationship between age, interocular differences in the corrected distance and near logMAR visual acuities, refractive errors, eyeball lengths, pupil sizes and higher order ocular aberrations on clinical measures of stereoacuity and aniseikonia in asymptomatic presbyopic habitual spectacle wearers.

Methods: 91 subjects underwent clinical assessment of i) subjective refractive error, ii) stereoacuity at 6m and 40 cm (Randot Stereotests), iii) aniseikonia at 6m (Awaya test along vertical and horizontal meridia) iv) higher order aberrations (Hartman-Shack aberrometer) v) eyeball length and pupil size (IOL master 700). The Pythagorean theorem was applied to each pair of aniseikonia values to calculate the resultant aniseikonia (AR).

Results: Mean (±sd,95%CI) age of the subjects was 56.2 years (±8.10,54.6-57.9). Root mean square (RMS) interocular differences(±sd,95%CI) in spherical refractive errors, eyeball lengths and pupil sizes were 0.66D(±0.93,0.47-0.85), 0.24mm(±0.33,0.17-0.31), 0.15mm(±0.11,0.12-0.17). The median (mode, interquartile range) values for AR were 2.8(1.0,1.3-4.0).

Significant correlations (p<.01) were revealed between:

a) distance stereoacuity and age as well as difference in the corrected distance visual acuity.

b) near stereoacuity and difference in the corrected distance and near visual acuities.

Conclusions: Depth perception is age-related, influenced by interocular difference in the corrected visual acuities but not related to interocular difference in pupil sizes, higher order aberrations or aniseikonia in older habitual spectacle wearers. Assessment of stereoacuity, and aniseikonia, in older persons may be useful in relation to preventing accidental mis-location and falls.