Highly Precise Eye Length Measurements in Children Aged 3 Through 12 Years

Abstract

To determine the feasibility, reliability, and validity of using partial coherence interferometry, a noncontact method that detects interference patterns from various layers of the eye, to measure axial length in young children. Methods: The right eye of 64 subjects (mean age, 8.4 y; age range, 3.4-12.9 y; best-corrected visual acuity Ն20/ 30) was measured. Subjects fixated monocularly on the collimated light pattern from a laser diode (the alignment beam) and the operator used a video monitor to align the corneal reflection in the optical path. Axial length was measured during an 0.8-second scan using interference patterns from a collimated short coherence superluminescence diode aligned coaxially with the laser diode. Five series of 16 readings each were obtained. The average axial length for each of the 5 series of readings was calculated. Main Outcome Measure: Axial length. Results: Within-subject precision of axial length measurements was high, with an overall SE of measurement of 8 µm for individual subjects across the 5 sessions (95% confidence interval, ±16 µm). Subgroup analysis showed that sex, age, spherical equivalent, and refractive error exerted statistically significant effects on precision, but all of the differences among subgroups were 3 µm or less and likely to be insignificant clinically. Axial length measured by partial coherence interferometry varied systematically, with factors known to influence eye length (ie, age and refractive error), further validating the measurement method. Conclusion: The partial coherence interferometry technique provides reproducible, extraordinarily precise eye length measurements in young children and should enable novel approaches to study eye growth and refractive development.

Effect of axial length and keratometry measurement error on intraocular lens implant power prediction formulas in pediatric patients

“…18,19 Partial coherence interferometry for axial length measurement has been shown to be very accurate but requires patient cooperation, and thus, may not be a viable option in infants, young children, and uncooperative children. 20,21 Our analysis demonstrates that an error in axial length or keratometry measurement can lead to a different post- The difference is not constant in the SRK/T, Holladay I, Hoffer Q, and Haigis formulas. The sensitivity of IOL prediction formulas to axial length change increases in the short axial length and higher keratometry range for all formulas, especially the Hoffer Q formula and less for the SRK/T, Holladay I, and Haigis formulas.…”

Axial Length Measurement Using Partial Coherence Interferometry in Myopic Children: Repeatability of the Measurement and Comparison with Refractive Components

“…Statistically, with an increase in the number of scans (n), the repeatability improves by 1/√n -, but consideration should be given to the trade-off relationship between the repeatability and safety of the measurement. Recently, Quinn et al 27 developed another noncontact AL measurement device that uses a super luminescence diode. This device is reported to reduce dispersion in the optic medium, and requires a lower level of measurement light, making possible a higher number of repetitive scans than with the IOLMaster.…”

In Vivo Human Choroidal Thickness Measurements: Evidence for Diurnal Fluctuations

“…15,16 The first group was composed of 64 patients of the Division of Pediatric Ophthalmology at The Children’s Hospital of Philadelphia (Philadelphia, PA) and ranged in age from 3 to 12 years. 15 The second group was composed of 39 University of Pennsylvania undergraduates, medical students, and employees (Greenberg KP, et al IOVS 2003;44: ARVO E-Abstract 3612). The third group was composed of 10 University of Pennsylvania undergraduates ranging in age from 18 to 24 years.…”

“…15,16 During each measurement session, the subject’s head position and corneal reflex were monitored and adjusted so that the central corneal reflex and alignment beam were coaxial. Subjects were encouraged to maintain fixation on the alignment beam of the PCI for the 0.8 second required for each measurement, and 80 PCI axial length tracings were acquired over a period of 5 to 7 minutes.…”

“…To extend our understanding of the choroid in humans, we then applied these methods to the question of diurnal variations in human choroidal thickness using data from subjects who participated in a previous study of diurnal variation in axial length. 15 …”