Anterior ocular surface sagittal height prediction

Agreement between extrapolated corneoscleral topographical data obtained during natural and retracted eyelid positions

PURPOSE

To examine the influence of aperture size (corneoscleral data coverage) on extrapolated scleral sagittal height data generated by the Pentacam HR derived from the Corneo Scleral Profile (CSP) software, by comparing measurements obtained during natural and retracted eyelid positions.

METHODS

Corneoscleral topography of the left eye of 20 young (age: 22 [3] years) healthy adults with normal corneas was measured using the Pentacam HR CSP with the eyelids in their natural primary gaze resting position and during eyelid retraction with a wire speculum. The measured and extrapolated sagittal height data were exported from the instrument and analysed over a range of chord diameters (10.0, 12.5, 15.0 and 17.5 mm) and locations (superior, inferior, nasal and temporal) using customised software.

RESULTS

Eyelid retraction increased data coverage (% of available data points within 360°) for the 12.5 and 15.0 mm chord diameters (by 25% and 35%, respectively, p < 0.001), but by less than 10% for the 10.0 and 17.5 mm chord diameters. Significant differences in extrapolated sagittal height data were observed between the natural and retracted eyelid positions with respect to chord diameter and location (both p < 0.001), with the greatest difference observed superiorly for a 17.5 mm chord diameter (mean extrapolated sagittal height difference, retracted minus natural: -447 ± 401 μm, p < 0.0001).

CONCLUSIONS

Eyelid retraction substantially increased data coverage for the 12.5 and 15.0 mm chord diameters. Significant differences in the extrapolated sagittal height data generated from measurements obtained during natural and retracted eyelid positions were observed for the superior location (12.5, 15.0 and 17.5 mm chord diameters) and inferior and nasal locations (17.5 mm chord diameter). Extrapolated sagittal height values obtained during the natural eyelid position were typically greater than those obtained with eyelid retraction, most likely due to the amount of measured data available for extrapolation.

2022 Glenn A. Fry Award lecture: Enhancing clinical assessment for improved ophthalmic management

ABSTRACT

Detailed clinical assessment is critical to allow sensitive evaluation of the eye and its management. As technology advances, these assessment techniques can be adapted and refined to improve the detection of pathological changes of ocular tissue and their impact on visual function. Enhancements in optical medical devices including spectacle, contact, and intraocular lenses have allowed for a better understanding of the mechanism and amelioration of presbyopia and myopia control. Advancements in imaging technology have enabled improved quantification of the tear film and ocular surface, informing diagnosis and treatment strategies. Miniaturized electronics, large processing power, and in-built sensors in smartphones and tablets capacitate more portable assessment tools for clinicians, facilitate self-monitoring and treatment compliance, and aid communication with patients. This article gives an overview of how technology has been used in many areas of eye care to improve assessments and treatment and provides a snapshot of some of my studies validating and using technology to inform better evidence-based patient management.

Corneoscleral junction angle in healthy eyes assessed objectively

PURPOSE

To introduce a fully objective method to measure corneoscleral junction (CSJ) angle and evaluate the CSJ angle in healthy eyes.

METHODS

Corneoscleral topography (Eye Surface Profiler, ESP) was acquired from the right eye of 105 healthy Caucasian subjects, ranging from 18 to 59 years old. From the raw anterior eye height data, the topographic limbus was automatically demarcated in 360 semi-meridians. Further, in limbal location, the CSJ angle was automatically calculated from corneoscleral height data using neighbouring auxiliary points for angle calculation. Additionally, CSJ angle was statistically analysed regionally.

RESULTS

The mean CSJ angle was 177.5 ± 1.1°. There is a mean difference of 7.7 ± 3.7° between the steepest (smallest) and flattest (largest) CSJ angle within the same eye. There exist statistically significant differences between temporal (178.2 ± 1.4°) and nasal (176.4 ± 1.1°) regions (paired t-test, p < 0.001), and between superior (178.1 ± 1.1°) and inferior (177.9 ± 1.1°) regions (p = 0.038). CSJ angle is correlated with limbus position (r = 0.43, p < 0.001).

CONCLUSION

CSJ angle is rotationally asymmetric. CSJ varies regionally, being the smallest (steepest) in the nasal region. Significant rough changes in CSJ angle were observed for some healthy individuals.