advertisement
Abstract #10364 Published in IGR 6-1
Diurnal axial length fluctuations in human eyes
Stone RA; Quinn GE; Francis EL; Ying GS; Flitcroft DI; Parekh P; Brown J; Orlow J; Schmid GInvestigative Ophthalmology and Visual Science 2004; 45: 63-70
PURPOSE: This study sought diurnal variations of eye length in human subjects, analogous to those reported in laboratory animals. METHODS: Seventeen subjects, aged seven to 53 (median 16) years with mean spherical equivalent refractive error -0.68 D (range, -3.00 to +1.00 D), underwent axial length measurements at multiple times during the day between 7 a.m. and 1 a.m. the following day, using partial coherence interferometry (PCI), a highly precise, noncontact method. Diurnal axial length measurements were obtained on two or more days in ten of these subjects. RESULTS: During at least one day, 15 subjects showed a statistically significant (ANOVA, p < 0.05) diurnal fluctuation of axial length, with a magnitude generally between 15 and 40 μm. From the diurnal tracings that fit a sine curve using statistical criteria, the mean period of fluctuation was 21.6 ± 4.33 hours (SD), the mean amplitude was 27.1 ± 11.9 μm (SD; range, 12.8-41.4 μm), and the maximum axial length tended to occur at midday. Each of the subjects with multiple daily measurements showed axial length fluctuations on at least one day, but there were day-to-day differences in the diurnal variations: most notably, four subjects showed axial length fluctuations on each day; in others, the fluctuations were not observed on each testing day. CONCLUSIONS: The human eye undergoes diurnal fluctuations in axial length, with a pattern suggesting maximum axial length at midday. Based on repeated measurements, these daily fluctuations may not appear regularly in all subjects, suggesting the possibility of physiologic influences that must be defined.
Dr. R.A. Stone. Division of Pediatric Ophthalmology, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
Classification:
6.12 Ultrasonography and ultrasound biomicroscopy (Part of: 6 Clinical examination methods)