Comparing Methods for Standardising Photographic Periocular Measurements: Optical Biometer versus Reference Sticker Analysis
Author: Jeremy T. Moreau
Base Hospital / Institution: University of Calgary, Calgary, Canada
ePoster presentation
Abstract ID: 25-363
Purpose
Photographic periocular measurements commonly use the corneal white-to-white (WTW) distance as a reference standard to calculate other periocular measurements such as MRD1 and MRD2. However, this approach has inherent limitations due to natural anatomical variations in WTW measurements. This study aimed to compare two methods of scale standardisation for photographic digital periocular measurements: using a 10mm reference sticker placed on the patient’s forehead versus optical biometer-derived WTW measurements.
Methods
In this retrospective comparative study, we evaluated 50 patients presenting to an oculoplastic surgery clinic. For each patient, we obtained bilateral WTW measurements using both an optical biometer (Zeiss IOLMaster) and digital photographs captured with a blue 10mm reference sticker placed on the patient’s forehead. Statistical analyses were carried out in Python and included Bland-Altman plots, correlation coefficients, and kernel density estimations to assess agreement between methods.
Results
The mean WTW measurements for the right eye were 11.98mm (SD=0.45) with the optical biometer and 11.25mm (SD=0.53) with the sticker method. For the left eye, measurements were 11.90mm (SD=0.48) and 11.31mm (SD=0.56) respectively. Correlation analysis showed a significant positive correlation between methods (p ≤ 0.0001). Agreement between methods is also demonstrated in Bland-Altman plots. Overall, optical biometer measurements were consistently larger than sticker-derived measurements, with a mean difference 0.73mm for the right eye and 0.59mm for the left eye.
Conclusion
This study provides evidence supporting the validity of using a reference sticker as a low-cost alternative to optical biometry for standardising scale in photographic digital periocular measurements. Furthermore, our study redemonstrates the anatomical variability in corneal white-to-white measurements, highlighting the value of including an additional scale reference to minimise systematic errors in derived measurements.
Additional Authors
| First name | Last name | Base Hospital / Institution |
|---|---|---|
| Antonio | Florido | University of Calgary, Calgary, Canada |
| Karim G. | Punja | University of Calgary, Calgary, Canada |
