Realistic Eye Research Articles

Optical Analysis of PresbyLASIK Treatment By a Light Propagation Algorithm

To evaluate the changes in the optical quality of corneas of hyperopic patients operated using central multifocal presbyLASIK treatment through the study of light patterns around the retinal plane. This study included eight hyperopic eyes that underwent central presbyLASIK surgery with Presby-one software using an H. Eye Tech Technovision excimer laser platform. Mean patient age was 57 years. Mean preoperative spherical equivalent refraction was 1.28 +/- 0.87 diopters (D). Mean distance decimal visual acuity with correction was 1.02 +/- 0.13 and without correction was 0.37 +/- 0.15. The optical quality was characterized by the Strehl ratio, the spot size on the retina, and objective decimal visual acuity calculated based on measured corneal topography using Fresnel propagation algorithm based on a realistic eye model. The postoperative spherical equivalent refraction was -0.55 +/- 0.48 D. The distance decimal visual acuity with correction was 0.94 and without correction was 0.70. The pseudoaccommodation range was 1.60 +/- 0.40 D. A good Pearson correlation coefficient was obtained (r2 = 0.86) for the linear fit between the real and calculated decimal visual acuity for the eight eyes. The Strehl ratio value on the retinal plane increased after the surgery by a mean factor of 4.7. With a complete characterization of the eye and a complete propagation algorithm (that takes into account all refractive surfaces in the eye at the same time), it is possible to evaluate the optical quality in eyes of patients who have undergone central presbyLASlK treatment.

Searching for asymmetries in the detection of gaze contact versus averted gaze under different head views: a behavioural study

Eye contact is a crucial social cue constituting a frequent preliminary to interaction. Thus, the perception of others' gaze may be associated with specific processes beginning with asymmetries in the detection of direct versus averted gaze. We tested this hypothesis in two behavioural experiments using realistic eye stimuli in a visual search task. We manipulated the head orientation (frontal or deviated) and the visual field (right or left) in which the target appeared at display onset. We found that direct gaze targets presented among averted gaze distractors were detected faster and better than averted gaze targets among direct gaze distractors, but only when the head was deviated. Moreover, direct gaze targets were detected very quickly and efficiently regardless of head orientation and visual field, whereas the detection of averted gaze was strongly modulated by these factors. These results suggest that gaze contact has precedence over contextual information such as head orientation and visual field.

Automated Eye Motion Using Texture Synthesis

Modeling human eyes requires special care. The goal of this paper is to synthesize realistic eye-gaze and blink motion, accounting for any possible correlations between the two. The technique adopts a data-driven texture synthesis approach to the problem of synthesizing realistic eye motion. The basic assumption is that eye gaze probably has some connection with eyelid motion, as well as with head motion and speech. But the connection is not strictly deterministic and would be difficult to characterize explicitly. A major advantage of the data-driven approach is that the investigator does not need to determine whether these apparent correlations actually exist. If the correlations occur in the data, the synthesis (properly applied) will reproduce them.

Mesoscale Assimilation of TMI Rainfall Data with 4DVAR: Sensitivity Studies

Sensitivity studies are performed on the assimilation of TRMM (Tropical Rainfall Measuring Mission) Microwave Imager (TMI) derived rainfall data into a mesoscale model, using a four-dimensional variational data assimilation (4DVAR) technique. A series of numerical experiments is conducted to evaluate the impact of TMI rainfall data on the numerical simulation of Hurricane Bonnie (1998). The results indicate that rainfall data assimilation is sensitive to the error characteristics of the data, and the inclusion of physics in the adjoint model. In addition, assimilating the rainfall data alone is helpful for producing a more realistic eye and rain bands in the hurricane, but does not ensure improvements in hurricane intensity forecasts. Further study indicated that it is necessary to incorporate TMI rainfall data together with other types of data, such as wind data into the model, in which case the inclusion of the rainfall data further improves the intensity forecast of the hurricane.

Centering mechanism for soft contact lenses.

A soft contact lens, because of its elasticity, can re-center itself over the cornea after it has been displaced by a blink. In this paper, a potential energy method is used to simulate the centering mechanism. Specifications for commercially available soft contact lenses and realistic eye shapes are used for the examples. With this technique we can compare the centering attributes of different lens and eye geometries.

Heating of spherical versus realistic models of human and infrahuman heads by electromagnetic waves

A numerical method based on a tensor integral equation has been employed to quantify the induced EM heating in realistic models of the human and infrahuman head. The head consists of a brain of realistic shape and eyes that are surrounded by a bony structure. The numerical method has also been used to determine the induced EM heating in spherical models of human and infrahuman heads and brains. The EM heating induced in the brain of the realistic model is lower than that induced in the brain of the spherical model. The bony stucture of the skull tends to attenuate heating of the brain, including the eyes.

Perceptual determinants of gaze aversion by normal and psychotic children: the role of two facing eyes.

AbstractThe perceptual determinants of gaze aversion by humans were examined in psychotic children with autistic symptoms, who persistently avoid eye-contact, and in normal children. Previous studies of normal adults have indicated that two concentric discoid elements, schematically resembling two facing eyes, are arousing stimuli. It was of interest to determine if similar eyelike schemata, as compared with less eyelike schemata of greater or lesser complexity, would elicit the least visual inspection as an arousal-reducing cut-off act. To clarify discrepancies in the literature as to whether normal and psychotic children differ in their sensitivity to prolonged eye-contact and concomitant readiness to gaze avert, these groups were compared for differential responsiveness to the same stimuli. Measurement of different inspection of eyelike schemata was accomplished using a special model-viewing apparatus in which two models were presented side-by-side in paired comparisons. The duration of each glance directed at a particular model was recorded on video tape and later measured with a stopwatch. Three experiments were performed. The first examined 10 normal and 10 psychotic children during presentations of 5 models comprising a blank model and models with I through 4 concentric discoid elements separated by the same interpupillary distance as are real human eyes. The second experiment examined 15 psychotic children using models presenting two concentric discoid elements in vertical, diagonal, and horizontal orientations. The third experiment examined 10 normal and 10 psychotic children using 5 models comprising two schematic facing eyes as represented by concentric discoid elements, more realistic eyes with staring and adverted irises, and closed eyes. The following results were obtained: I. A model won a particular comparison bout if it was looked at longer than its comparison model. In all experiments and in both groups of children, the model presenting two horizontally placed concentric discoid elements won the fewest number of paired comparison bouts against the field of other models. The only exception occurred for normals in the first experiment in which the blank model won fewer comparison bouts than the model presenting two concentric discoid elements. 2. For the over-all duration of model inspection in the first experiment, the psychotics looked longer at the models than did the normals. However, these groups did not differ as much for the model with two concentric discoid elements. Both groups, particularly the psychotics, looked less at the model presenting two concentric discoid elements than at models presenting other arrangements of concentric discoid elements in the first experiment. Similarly in the third experiment, both groups looked less at the model with two concentric discoid elements than at models with staring and averted irises, albeit these differences were not significant. Normals and psychotics did not differ appreciably in their over-all looking at the more realistic eyelike schemata in the third experiment. With respect to the spatial orientation of two concentric discoid elements in the second experiment, the psychotics looked the least at the model presenting two discoid elements in the horizontal plane. In light of the clinical observations that normals and psychotics differ in gaze behavior, the findings that normal adults are aroused by two concentric discoid elements, and the theoretical aspects of the cut-off hypothesis, the results suggest the following: I. Two horizontally placed concentric discoid elements, schematically resembling two facing eyes, are provocative stimuli eliciting less visual inspection in accordance with the cut-off hypothesis. 2. The lack of differential gazing by normals and psychotics during presentations of models with two schematic facing eyes seems to indicate that, in the absence of supporting features of a human face, two schematic facing eyes were equally provocative to both groups of children.