Simultaneous drift, microsaccades, and ocular microtremor measurement from a single noncontact far-field optical sensor

Abstract

We report on the combined far-field measurement of the three involuntary eye movements, drift, microsaccades, and ocular microtremor (OMT), using a noncontact far-field optical method. We review the significance of the smallest and least measured, and thus least understood, of the three, OMT. Using modern digital imaging techniques, we perform detailed analysis, present experimental results, and examine the extracted parameters using a noncontact far-field sensor. For the first time, in vivo noncontact measurements of all fixational in-plane movements of the human eye are reported, which simultaneously provide both the horizontal (left-right) and vertical (up-down) displacement results.

Correlation between elastic energy stored in an eye and visual field progression in glaucoma

“…Some researchers explain this relationship in terms of similarity in tissue constitutions; the cornea, lamina cribrosa and peripapillary sclera have biomechanical properties in common[ 15 – 18 ], and consequently, a higher CH may somehow represent a more energy-dissipative structure at the optic nerve head. Considering recent studies that revealed eyes receive daily incessant stress in the form of ocular microtremors[ 19 ], pulsatility[ 20 ], blinking,[ 21 , 22 ] and general eye movements,[ 23 , 24 ] we hypothesize in the current study that external stress that occurs repeatedly within a short period of time contribute to glaucomatous change by giving excessive energy load to the optic disc. When external stresses are placed on an eyeball, some energy is absorbed by the damping capacity of an eye, but the remaining unabsorbed energy can be a stress on the posterior segments of an eye, including the structures around the optic nerve head, which can cause damage to the axons and eventually the retinal ganglion cells.…”

Comparison of two analyzer measurements focusing on material stiffness among normal, treatment-naïve, and treated glaucoma eyes

“…www.nature.com/scientificreports/ Furthermore, stiffer ocular tissues may have lower energy dissipation or damping capacity. We have argued in previous studies 39,40 that dynamic changes in IOP and eye globe deformation caused by daily phenomena such as pulsation 41 , blinking 42,43 , or eye movements 44,45 , may cause damage to the optic nerve head, and that eyes with smaller energy dissipation may be more vulnerable to such stress and prone to faster progression of glaucoma. Quassim et al 27 recently reported that a higher SP A1 value was significantly associated with faster structural and functional progression of glaucoma.…”

Measuring Ocular Aberrations Sequentially Using a Digital Micromirror Device

“…Larger variations between the reconstructed wavefronts appeared when measuring the real eye in comparison to the previous results with the artificial eye. This could be due to the natural movement of the eye, which includes both voluntary and involuntary movements, even when fixating on a given target [ 19 ]. Fixation time lasted approximately 200–300 ms [ 20 , 21 ], with large variability between subjects, which falls well below the required DMD-WFS scan time.…”

“…Scans performed at 13 FPS were to suffice when measuring ocular aberrations with both 5 × 5 and 10 × 10 DMD cell sampling, and the effect of scanning speed between 5 and 20 FPS was analyzed. However, variations in the measured wavefronts are still present due the continuous involuntary movements of the eye during fixation including tremors, drifts, and microsaccades [ 19 , 20 , 21 ], where further increasing the speed would improve accuracy and repeatability. Changes in the tear film, which is known to be dynamic, may also cause changes in the measurements of ocular aberrations [ 23 ].…”