Age-associated increase in pulsatile axial motion of the cornea

Abstract

Purpose : Pulsatile axial motion of the cornea has been reported in the past. However, it is unclear which factors determine such motion. The objective of this study was to quantify pulsatile corneal displacements in healthy human subjects and evaluate associations with age and intraocular pressure (IOP).

Methods : The study was approved by the Ohio State University IRB and was conducted according to the Declaration of Helsinki. Volunteers with no known corneal diseases (n=22) were recruited and informed consent was obtained. The IOP and ocular pulse amplitude (OPA) of both eyes were measured by a PASCAL Dynamic Contour Tonometer. The corneas of both eyes were imaged using a high-frequency ultrasound system (MS700, FUJIFilm VisualSonics, Toronto) at 128 frames per second. During measurements, the subject sat at an anti-vibration table and the head was secured to a head-and-chin rest. One thousand consecutive ultrasound B-mode images and radiofrequency data of the central 5.7 mm cornea along the nasal-temporal meridian were obtained from each eye. Corneal axial displacements were calculated using an ultrasound speckle tracking technique (Clayson et al, TVST, 2020) and the average magnitude from three displacement cycles was obtained in each eye. Pearson correlation was used to evaluate the relationship between corneal displacements and age, IOP, and OPA.

Results : The measured subjects were from 22 to 72 years old (mean±SD = 41.6±14.9 years). The IOP was 16.7±2.7 mmHg, and the OPA was 2.6±0.7 mmHg. The peak magnitudes of corneal axial displacement were 46.2±27.1 µm (n=44, including both eyes). Corneal displacement was significantly associated with age (r=0.478, p=0.024; Fig. 1), but not IOP or OPA (r=0.1 or 0.05, p’s>0.2) in OD. Similar results were found in OS (data not shown).

Conclusions : This study showed an age-associated increase in corneal axial motion, which was not related to IOP or OPA. As age is known to be associated with tissue stiffening, the results indicated that tissue properties may affect pulsatile corneal motion. Future studies will investigate the spatial distribution of axial displacements in the cornea and determine eye-specific corneal biomechanical properties that may change with age or disease.

This is a 2020 ARVO Annual Meeting abstract.

 

Fig. 1: Corneal axial motion increased with age in normal human subjects (n=22) as measured by ultrasound speckle tracking (R=0.478, p=0.024).