Measurement Of Accommodation Response Research Articles

Dynamic Measurement of Accommodation and Pupils Size Under Different Lighting Condition

Purpose : This study investigated the dynamic measurement of accommodation response and pupil size change by different lighting conditions and its effect on visual function. Methods : Seventeen (23.06±0.51) students participated who had no history of ocular surgery. All participants had normal binocular vision and more than 0.8 visual acuity. Dynamic accommodation and pupil size were measured using open-type auto-refractor(WAM-5500) with 5 Hz frequency under three lighting conditions (photopic vision, mesopic vision, and scotopic vision). Accommodation stimulus in the distance of 40 cm, 40~30 cm, 30 cm, 30~20 cm, and 20 cm were induced for 5 seconds. In addition, the visual function such as VA and contrast sensitivity were measured. Results : The accommodation response was the highest in photopic vision and the lowest in scotopic vision(p＜0.050). The change of pupil size was measured to be the smallest under photopic vision and the largest under scotopic vision(p＜0.050). The visual acuity and contrast sensitivity also showed the highest value in photopic vision and the lowest value in scotopic vision(p＜0.050). Conclusion : This study demonstrated the dynamic changes of accommodation and pupil size under different lighting conditions. Under low lighting condition, accommodative response were less than accommodative stimulus and visual function deteriorated accordingly. It showed continuous changes of accommodation under static condition, therefore several measurement of accommodation or visual function may be recommend.

Measurement of accommodation response in integral photography images

A method of displaying a multiview image set prepared by a computer on an electronic display device based on integral photography has been formulated. With the device, accommodation response was measured and the result that the accommodation response linearly changed within and outside the range of depth of focus was obtained. In contrast, in the measurement of the accommodation response using the stereoscopic image, the accommodation response showed a linear change within and outside the depth of focus at the spatial resolution of three cycle per degree (cpd) or less. Therefore, it can be considered that the measurement result of the accommodation response for integral photography with a spatial resolution of 3 cpd or less cannot be used to determine whether it is influenced by the integral photography display method or spatial resolution reduction. From these results, we found that spatial resolution is required to be 3 cpd or more when outside of the range of depth of focus in the measurement of the accommodation response for integral photography.

Effect of even and odd-order aberrations on the accommodation response.

To investigate the potential effect that odd and even-order monochromatic aberrations may have on the accommodation response of the human eye. Eight healthy subjects with astigmatism below 1 D, best corrected visual acuity 20/20 or better and normal findings in an ophthalmic examination were enrolled. An adaptive optics system was used in order to measure the accommodation response of the subjects' eyes under different conditions: with the natural aberrations being present, and with the odd and even-order aberrations being corrected. Three measurements of accommodation response were monocularly acquired at accommodation demands ranging from 0 to 4 D (0.5 D step). The accommodative lag was greater for the accommodative demands of 1.5, 3, 3.5 and 4 D for the condition in which the even-order aberrations were corrected, in comparison to that obtained for the natural aberrations and corrected odd-order aberrations for the same accommodation demands. No statistically significant differences were found between the accommodation responses under the three conditions. The odd and even-order aberrations are not helping the visual system to accommodate, because their partial correction do not affect the accommodation performance.

Assessing the accommodation response after near visual tasks using different handheld electronic devices.

To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0.25 m from the subject's eyes. Three measurements of accommodation response were monocularly acquired at stimulus vergences ranging from 0 to 4 D (1-D step). No statistically significant differences were found in the accommodation responses among the conditions. A moderate but gradually increasing root mean square, coma-like aberration was found for every condition. Conversely, the spherical aberration decreased as stimulus vergences increased. These outcomes were identified in comparison to the one-to-one ideal accommodation response, implying that a certain lag value was present in all stimulus vergences different from 0 D. The results support the hypothesis that the difference between the ideal and real accommodation responses is mainly attributed to parameters associated with the accommodation process, such as the near visual acuity, depth of focus, pupil diameter, and wavefront aberrations. The wavefront aberrations were dependent on the 3-mm pupil size selected in this study. The accommoda tion response was not dependent on the electronic device employed in each condition, and it was mainly associated with young age and level of amplitude of accommodation of the subjects.

Analysis of Condition for Integral Floating Display Inducing Proper Accommodation Responses

The condition for the integral floating display is analyzed and evaluated, which elicits the distinguished accommodation responses to different axial locations of targets. The analysis is carried out to derive condition which helps to devise such a system. And measurements of accommodation response from four subjects are conducted to confirm the agreements with the analytical results, by using the auto-refractometer. The two sample Kolmogorov–Smirnov test is applied to evaluate the measurement results qualitatively. The robust agreements between the analysis and the empirical results are observed. This research can be applied in the optimization of augmented reality or virtual reality devices to provide effective three-dimensional depth cues and relieve viewing discomforts.

Measurement accuracy in accommodative response by the Nott method

The measurement of accommodative response is usually performed by means of the Nott method. The accommodative response values were obtained as described in the bibliography and considering that the neutralizing lens shapes the target image. The values in accommodative response differ according to the calculation method utilized.The accommodation and convergence values when the target is placed 40cm away from the glasses are not the same in emmetropic and ametropic subjects. At the position of the effective binocular object, the initial values are indeed the same for both types of subjects. Comparing with experimental measurements using the Monocular Estimate Method (Mem), it was obtained the same values given the effect of the neutralizing lens.Optimizing the Nott method would require placing the target at a position where the effective binocular object is 40cm. Furthermore, the effect of the neutralizing lens should be considered in the calculation method.

Measurement of accommodation response of human eye to integral floating display.

The dioptric responses of human eyes to floating images at different depths reconstructed by an integral floating display are measured with an open-field autorefractor and analyzed according to observer recognition of the accommodation depth cue. Two targets are randomly presented approximately 1.75D from the observers and have a separation of 0.15D, corresponding to approximately 5cm. Two subjects participate, and over 500 responses are measured during each experimental trial. The frequency distribution profiles of the responses to targets at different locations are obtained and analyzed. The results confirm that the subjects focused on the floating targets and not on the surface of the optical component. In this paper, an analysis of the separation between the peaks of the frequency distribution profiles is presented that confirms that the integral floating display could induce the accommodation response to provide the corresponding depth stimulus.

Simultaneous measurement of objective refraction, accommodation response and axial length of the human eye

Accurate measurements of ocular biometry and objective refraction are of vital importance to research laboratories working in the area of refractive error development and oculomotor function. A number of commercially available instruments can provide these measurements, and are used in both their intended modes, and with modifications to increase their research utility. A limitation that exists currently is the inability to conduct simultaneous measurements of refractive error or accommodation response, and the axial length of the same eye. In this technical note we provide details of a method to adapt the Zeiss IOLMaster and the Shin-Nippon SRW-5000 infrared optometer to simultaneously measure refraction and axial length. The optical modification used to combine the measurement paths of the IOLMaster and SRW-5000 instruments consists of a narrow band-pass filter, and optical relay to extend the working distance of the IOLMaster, and an electronic system to provide synchronisation between the IOLMaster and the SRW-5000 continuous accommodation recording system. The optical modification was tested on model eyes, and on a cohort of 20 human eyes. The combined system was then used to measure accommodation response and axial length simultaneously in a single participant. Inclusion of the optical modification in the IOLMaster pathway induced a 0.004 mm shift in the average measurement of a calibration eye, and an average difference of 0.001 mm for a cohort of human eyes. For the SRW-5000, inclusion of the modified optics induced a +0.15 D shift in the spherical component of refraction measurements made on a model eye, and an average shift of +0.12 D in the spherical component of measurements made on a cohort of human eyes. Simultaneous measurement of accommodation response and axial length in a single participant revealed that a change in stimulus vergence from 0 to 5 D caused an average accommodation response of 3.89 D, and an average transient axial length change of 0.059 mm. The system described provides a useful method of achieving simultaneous measurements of axial length, objective refraction and accommodation response in a human eye.

37.4: Accommodation Response in Viewing Integral Imaging

AbstractVisual discomfort has been the subject of considerable research in relation to stereoscopic and autostereoscopic displays. In this paper, the measurement of accommodation response in viewing integral imaging has been performed. Integral imaging is the three‐dimensional display technology proposed by Lippmann which shows full parallax images and does not need any additional equipment. Recently the integral imaging system was rapidly improved thanks to the progress of flat panel displays such as liquid crystal display, however so far, no definitive answer has been given to the visual fatigue related with viewing integral imaging system. The measurement results indicate that the accommodation response was in proportion to the perceived depth in integral imaging just as when the observer views real objects. The accommodation response is concluded not to be fixed on the display panel, but to follow similar response as if the physical objects exist on each depth.

Overaccommodation, Underaccommodation, and the Clinical Phoropter

To explore the degree to which a phoropter can induce overaccommodation (instrument myopia) and/or underaccommodation , 19 college-age subjects participated in a series of measurements of accommodation response. Accommodation responses were assessed while subjects looked through a phoropter (both with standard 19-mm viewing apertures and through 2-mm artificial pupils) and when no phoropter was present. Subjects were tested both monocularly and binocularly, and under three stimulus conditions (near target, far target, and total darkness). Even without the phoropter , subjects tended to overaccommodate for the far target. The 19-mm phoropter produced no significant overaccommodation or underaccommodation effects over and above those observed without the presence of the phoropter . The 2-mm artificial pupils produced significantly more underaccommodation for the near target. Results indicate a tendency for accommodation response to approach an intermediate resting position as the viewing situation becomes impoverished.