Purchase this article with an account.
Kotaro Ishii, Yasuhiro Ishikawa, Hikaru Iwasaki, Toshihiro Kameda, Tetsuro Oshika; Vibrational Analysis Of The Ocular Surface Using Continuous Wavelet Transform. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2802.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The wall of the eyeball, which consists of the cornea and sclera, has the biodynamic features of a viscoelastic object. However, there have been very few reports that have analyzed the viscoelastic features of the eyeball wall. In this study, we applied external force by compressed air focusing on the cornea, and analyzed the vibrations which arose on the surface using continuous wavelet transform (CWT).
Ocular surface vibrations were measured from the fluctuation of the light signal intensity by reflection of the infrared light irradiated to the cornea. CWT was applied to the light signal-time sequence, and a time-frequency analysis was conducted. In 50 eyes of 25 healthy subjects, the frequency of vibration of the ocular surface, the central corneal thickness (CCT), the cornea curvature radius, and the axial length were measured. The intraocular pressure (IOP) was measured using Goldmann applanation tonometry (GAT) and a Dynamic Contour Tonometer (DCT).
In the frequency spectrum analysis of the ocular surface vibration, the frequency peak was obtained at 507.8±243.2 Hz, 1222.7±208.0 Hz, 1886.7±283.4 Hz, and 2460.9±318.2 Hz as the average value. The vibrations were put in order from the 1st to 4th peak based on the number region of the low frequency waves. The 4th peak showed a significant correlation with age (Pearson's r = -0.333, p = 0.0176), GAT-IOP (r = 0.460, p<0.001), DCT-IOP (r = 0.416, p = 0.0024), and the axial length (r = 0.428, p = 0.0017).
Two or more vibrations were intermingled in the ocular surface vibrations which arose in the minute external force resulting from compressed air. The time-frequency analysis which used CWT efficiently separated these vibrations. The possibility that the internal structure of the eyeball could be noninvasively studied from the oscillating analysis on the ocular surface was therefore demonstrated.
This PDF is available to Subscribers Only