Technical note: measurement of retinal contour and supine axial length using the Zeiss IOLMaster.

Accurate and repeatable assessments of ocular biometric factors are of vital importance to research laboratories conducting studies of ametropia. This is of particular importance to studies assessing the efficacy of myopia control strategies, and when investigating the effect of accommodation and posture on ocular biometry. In this technical note, two novel adaptations of the Zeiss IOLMaster are described: an adaptation to enable measurement of the axial length of the eye of a subject in a supine position, and an attachment to enable measurement of peripheral ocular dimensions and plotting of the central 80 degrees of the retina relative to the anterior corneal surface. Pilot data obtained using these modifications to the instrument are presented.

Transient Axial Length Change during the Accommodation Response in Young Adults.

PURPOSE: To measure the degree of transient axial elongation during the accommodation response in emmetropic and myopic young adults. To evaluate the effect of refractive error and accommodative demand on transient axial elongation of the eye. METHODS: Axial length of the right eye was measured in 30 emmetropes and 30 myopes, by using the IOLMaster (Carl Zeiss Meditec, Inc., Dublin, CA), while accommodative stimuli of 0, 2, 4 and 6 D were presented with a Badal optometer. RESULTS: Axial length increased in both emmetropic and myopic subjects during short periods of accommodative stimulation. Greater transient increases in axial length were observed in myopic than in emmetropic subjects. The mean axial elongation with a 6-D stimulus to accommodation was 0.037 mm in emmetropes and 0.058 mm in myopes (P = 0.02). The degree of transient axial elongation correlated well with the stimulus to accommodation in emmetropes and myopes. Anterior chamber depth decreased, on average, by 0.19 mm in emmetropes and 0.18 mm in myopes when observing a 6-D stimulus to accommodation. CONCLUSIONS: During relatively short periods of accommodative stimulation, axial length increases in both emmetropic and myopic young adults. At higher levels of accommodative stimulation, a significantly greater transient increase in axial length is observed in myopic subjects than in their emmetropic counterparts.