-
Journal of Vision Feb 2024Stereoscopic imagery often aims to evoke three-dimensional (3-D) percepts that are accurate and realistic-looking. The "gap" between 3-D imagery and real scenes is...
Stereoscopic imagery often aims to evoke three-dimensional (3-D) percepts that are accurate and realistic-looking. The "gap" between 3-D imagery and real scenes is small, but focus cues typically remain incorrect because images are displayed on a single focal plane. Research has concentrated on the resulting vergence-accommodation conflicts. Yet, incorrect focus cues may also affect the appearance of 3-D imagery. We investigated whether incorrect focus cues reduce perceived realism of 3-D structure ("depth realism"). Experiment 1 used a multiple-focal-planes display to compare depth realism with correct focus cues vs. conventional stereo presentation. The stimuli were random-dot stereograms, which isolated the role of focus cues. Depth realism was consistently lower with incorrect focus cues, providing proof-of-principle evidence that they contribute to perceptual realism. Experiments 2 and 3 examined whether focus cues play a similar role with realistic objects, presented with an almost complete set of visual cues using a high-resolution, high-dynamic-range multiple-focal-planes display. We also examined the efficacy of approximating correct focus cues via gaze-contingent depth-of-field rendering. Improvements in depth realism with correct focus cues were less clear in more realistic scenes, indicating that the role of focus cues in depth realism depends on scene content. Rendering-based approaches, if anything, reduced depth realism, which we attribute to their inability to present higher-order aspects of blur correctly. Our findings suggest future general 3-D display solutions may need to present focus cues correctly to maximise perceptual realism.
Topics: Humans; Cues; Accommodation, Ocular; Technology; Perception
PubMed: 38411956
DOI: 10.1167/jov.24.2.13 -
Clinical Optometry 2024Myopia control lenses have been shown to modify visual function; however, it is arguable if these changes are short-term or long-term. We investigated the changes in...
Myopia control lenses have been shown to modify visual function; however, it is arguable if these changes are short-term or long-term. We investigated the changes in accommodative behaviour and binocular vision functions of Malay myopic children who participated in a myopia control trial utilising spectacle lenses (n = 40). This article presents baseline accommodation and binocular vision measurements. The mean (± SD) age, spherical equivalent measured by cycloplegic autorefraction, and axial length (AL) for the right eyes were 10.00 ± 1.47 years, -3.02 ± 1.20 D, and 24.42 ± 0.93 mm, respectively. All participants had good distance and near visual acuities with high-contrast charts (100%), which were significantly better than low-contrast charts (10%) ( < 0.001). The mean (± SD) accommodative lag at baseline was 1.14 ± 0.35 D, while monocular and binocular accommodative amplitudes were 15.35 ± 2.07 D and 16.82 ± 2.27 D, respectively. Malay schoolchildren in this study were more esophoric at near compared to distance, with an accommodative-convergence over accommodation (AC/A) ratio of 5.64 ± 0.66 ∆/D. A higher degree of myopia was found to be associated with a longer AL ( = -0.49, < 0.05) and higher esophoria at near ( = -0.46, < 0.05). These baseline measures are consistent with data from other studies showing that myopic children have a high accommodative lag, an elevated AC/A ratio, a longer AL, and are more esophoric at near. The measures reported herein will serve as a basis for examining changes that occur within 12 months of wearing myopia control spectacle lenses.
PubMed: 38405333
DOI: 10.2147/OPTO.S432496 -
American Journal of Ophthalmology Case... Jun 2024To present an uncommon cause of intermittent angle closure in a young adult patient presenting with intermittent headache and blurry vision exacerbated by accommodation.
PURPOSE
To present an uncommon cause of intermittent angle closure in a young adult patient presenting with intermittent headache and blurry vision exacerbated by accommodation.
OBSERVATIONS
A 37-year-old man reported experiencing intermittent blurry vision, headache, and pain in both eyes associated with prolonged periods of reading beginning at age 17. Serial intraocular pressure (IOP) measurements showed an increase in IOP from 14 to 32 mmHg in the right eye and from 9 to 37 mmHg in the left eye after 145 minutes of sustained accommodation while sitting up. IOP did not normalize after laser peripheral iridotomy but did normalize after clear lens extraction.
CONCLUSIONS AND IMPORTANCE
This case characterized a rare presentation of accommodation-induced IOP elevation in a young adult male that resolved only after clear lens extraction. The clinical takeaway was the importance of considering accommodation-associated angle closure in patients presenting with high intraocular pressures, eye strain, and/or headache with accommodative activities. Notable symptoms that should raise suspicion for this syndrome include halos, changes in visual acuity, and headache with accommodation. We suggested that patients presenting with these symptoms be followed closely, with a full glaucoma evaluation including gonioscopy and possible ultrasound biomicroscopy to assess for pediatric eversional angle closure with headache, plateau iris, angle closure glaucoma, and lens-induced angle closure.
PubMed: 38389701
DOI: 10.1016/j.ajoc.2024.102014 -
International Journal of Ophthalmology 2024To investigate the frequency and associated factors of accommodation and non-strabismic binocular vision dysfunction among medical university students.
AIM
To investigate the frequency and associated factors of accommodation and non-strabismic binocular vision dysfunction among medical university students.
METHODS
Totally 158 student volunteers underwent routine vision examination in the optometry clinic of Guangxi Medical University. Their data were used to identify the different types of accommodation and non-strabismic binocular vision dysfunction and to determine their frequency. Correlation analysis and logistic regression were used to examine the factors associated with these abnormalities.
RESULTS
The results showed that 36.71% of the subjects had accommodation and non-strabismic binocular vision issues, with 8.86% being attributed to accommodation dysfunction and 27.85% to binocular abnormalities. Convergence insufficiency (CI) was the most common abnormality, accounting for 13.29%. Those with these abnormalities experienced higher levels of eyestrain (=69.518, <0.001). The linear correlations were observed between the difference of binocular spherical equivalent (SE) and the index of horizontal esotropia at a distance (=0.231, =0.004) and the asthenopia survey scale (ASS) score (=0.346, <0.001). Furthermore, the right eye's SE was inversely correlated with the convergence of positive and negative fusion images at close range (=-0.321, <0.001), the convergence of negative fusion images at close range (=-0.294, <0.001), the vergence facility (VF; =-0.234, =0.003), and the set of negative fusion images at far range (=-0.237, =0.003). Logistic regression analysis indicated that gender, age, and the difference in right and binocular SE did not influence the emergence of these abnormalities.
CONCLUSION
Binocular vision abnormalities are more prevalent than accommodation dysfunction, with CI being the most frequent type. Greater binocular refractive disparity leads to more severe eyestrain symptoms.
PubMed: 38371255
DOI: 10.18240/ijo.2024.02.22 -
Scientific Reports Feb 2024This research uses mathematical modelling to evaluate the influence of the ligament of Wieger on the crystalline lens shape at rest, and during accommodation. An...
This research uses mathematical modelling to evaluate the influence of the ligament of Wieger on the crystalline lens shape at rest, and during accommodation. An axisymmetric model of the anterior segment, including the ligament of Wieger, was created using the finite element method. Different conditions including variations of stiffness and positions of the ligament, with and without the ligament, were tested to see how they affected lens curvature and optical power. Adding the ligament of Wieger to the simulation had a noticeable impact on the optical power of the lens, particularly on the posterior surface power and total power. Ligament stiffness and width significant influenced the accommodative range of the eye by - 0.95D and - 2.39D for ligaments with the same and 3× the stiffness of the capsular bag, respectively. Ligament width and inner diameter had negligible effects on lens thickness but did have significant effects on posterior surface power and accommodation. In this simulation, we found that the ligament of Wieger can significantly affect the lens shape, both at rest and during accommodation, and may need to be considered in lens models.
PubMed: 38369631
DOI: 10.1038/s41598-024-54674-w -
Journal of Biological Rhythms Jun 2024The pupil modulates the amount of light that reaches the retina. Not only luminance but also the spectral distribution defines the pupil size. Previous research has...
The pupil modulates the amount of light that reaches the retina. Not only luminance but also the spectral distribution defines the pupil size. Previous research has identified steady-state pupil size and melatonin attenuation to be predominantly driven by melanopsin, which is expressed by a unique subgroup of intrinsically photosensitive retinal ganglion cells (ipRGCs) that are sensitive to short-wavelength light (~480 nm). Here, we aimed to selectively target the melanopsin system during the evening, while measuring steady-state pupil size and melatonin concentrations under commonly experienced evening light levels (<90 lx). Therefore, we used a five-primary display prototype to generate light conditions that were matched in terms of L-, M-, and S-cone-opic irradiances, but with high and low melanopic irradiances (~3-fold difference). Seventy-two healthy, male participants completed a 2-week study protocol. The volunteers were assigned to one of the four groups that differed in luminance levels (27-285 cd/m). Within the four groups, each volunteer was exposed to a low melanopic (LM) and a high melanopic (HM) condition. The two 17-h study protocols comprised 3.5 h of light exposure starting 4 h before habitual bedtime. Median pupil size was significantly smaller during HM than LM in all four light intensity groups. In addition, we observed a significant correlation between melanopic weighted corneal illuminance (melanopic equivalent daylight illuminance [mEDI]) and pupil size, such that higher mEDI values were associated with smaller pupil size. Using pupil size to estimate retinal irradiance showed a qualitatively similar goodness of fit as mEDI for predicting melatonin suppression. Based on our results here, it remains appropriate to use melanopic irradiance measured at eye level when comparing light-dependent effects on evening melatonin concentrations in healthy young people at rather low light levels.
Topics: Humans; Male; Melatonin; Pupil; Young Adult; Rod Opsins; Adult; Light; Circadian Rhythm; Retinal Ganglion Cells
PubMed: 38348477
DOI: 10.1177/07487304241226466 -
Journal of Optometry 2024To analyze binocular vision of individuals aged 18 to 35 years diagnosed with keratoconus, utilizing spectacles and rigid gas-permeable (RGP) contact lenses. Research... (Comparative Study)
Comparative Study
PURPOSE
To analyze binocular vision of individuals aged 18 to 35 years diagnosed with keratoconus, utilizing spectacles and rigid gas-permeable (RGP) contact lenses. Research was led by the Universidad Autónoma de Aguascalientes, México and Fundación Universitaria del Área Andina Pereira, Colombia.
METHODS
A single center, prospective non-randomized, comparative, interventional, open-label study, in which the differences in binocular vision performance with both spectacles and RGP contact lenses was carried out from December 2018 to December 2019. Sampling was performed according to consecutive cases with keratoconus that met the inclusion criteria until the proposed sample size was reached.
RESULTS
Rigid gas-permeable (RGP) contact lenses notably enhanced distance and near visual acuity in keratoconus patients compared to spectacles. Visual alignment analysis shows exophoria at both distances and is slightly higher with RGP contact lenses. The difference was statistically significant (p<0.05), with 82.5 % presenting compensated phoria with spectacles and pnly 42.50% with RGP contact lenses. Stereoscopic vision improved while wearing RGP contact lenses (42.59 %), although accommodation and accommodative flexibility remained within normal ranges.
CONCLUSIONS
Patients with keratoconus fitted with RGP contact lenses have improved binocular vision skills such as visual acuity, stereopsis, and accommodative flexibility. However, even when the vergence and motor system is decompensated with respect to normal ranges, the range between break and recovery points for both fusional reserves and the near point of convergence (NPC) improves with the use of RGP contact lenses, giving indications of an adaptive condition of the motor system from the medium to the long term.
Topics: Humans; Keratoconus; Eyeglasses; Adult; Vision, Binocular; Visual Acuity; Male; Prospective Studies; Young Adult; Female; Contact Lenses; Adolescent
PubMed: 38324957
DOI: 10.1016/j.optom.2024.100514 -
Experimental Eye Research Mar 2024The ocular lens is the primary organ within the eye responsible for accommodation. During accommodation, the lens is subject to biomechanical forces. We previously...
The ocular lens is the primary organ within the eye responsible for accommodation. During accommodation, the lens is subject to biomechanical forces. We previously demonstrated that stretching the porcine lens can increase lens epithelial cell proliferation. Although murine lenses are commonly employed in lens research, murine lens stretching has remained unexplored. Murine lens stretching thus represents a novel source of potential discovery in lens research. In the present study, we describe a method for stretching the murine lens by compressing the murine globe embedded in a hydrogel. We hypothesized that, as the eye is compressed along the optic axis, the lens would stretch through zonular tension due to the equatorial region of the eye bulging outward. Our results showed that this led to a compression-dependent increase in murine lens epithelial cell proliferation, suggesting that compression of the embedded murine globe is a viable technique for studying the mechanobiology of the lens epithelium.
Topics: Animals; Swine; Mice; Hydrogels; Lens, Crystalline; Accommodation, Ocular; Cell Proliferation
PubMed: 38311284
DOI: 10.1016/j.exer.2024.109809 -
Journal of Physiological Anthropology Jan 2024Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of... (Review)
Review
BACKGROUND
Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of myopia during early childhood has heightened the risk of developing high myopia and related sight-threatening eye conditions in adulthood. This surge in myopia rates, occurring within a relatively stable genetic framework, underscores the profound influence of environmental and lifestyle factors on this condition. In this comprehensive narrative review, we shed light on both established and potential environmental and lifestyle contributors that affect the development and progression of myopia.
MAIN BODY
Epidemiological and interventional research has consistently revealed a compelling connection between increased outdoor time and a decreased risk of myopia in children. This protective effect may primarily be attributed to exposure to the characteristics of natural light (i.e., sunlight) and the release of retinal dopamine. Conversely, irrespective of outdoor time, excessive engagement in near work can further worsen the onset of myopia. While the exact mechanisms behind this exacerbation are not fully comprehended, it appears to involve shifts in relative peripheral refraction, the overstimulation of accommodation, or a complex interplay of these factors, leading to issues like retinal image defocus, blur, and chromatic aberration. Other potential factors like the spatial frequency of the visual environment, circadian rhythm, sleep, nutrition, smoking, socio-economic status, and education have debatable independent influences on myopia development.
CONCLUSION
The environment exerts a significant influence on the development and progression of myopia. Improving the modifiable key environmental predictors like time spent outdoors and engagement in near work can prevent or slow the progression of myopia. The intricate connections between lifestyle and environmental factors often obscure research findings, making it challenging to disentangle their individual effects. This complexity underscores the necessity for prospective studies that employ objective assessments, such as quantifying light exposure and near work, among others. These studies are crucial for gaining a more comprehensive understanding of how various environmental factors can be modified to prevent or slow the progression of myopia.
Topics: Child, Preschool; Child; Humans; Prospective Studies; Myopia; Refraction, Ocular; Accommodation, Ocular; Circadian Rhythm
PubMed: 38297353
DOI: 10.1186/s40101-024-00354-7 -
Scientific Reports Jan 2024Previous studies have demonstrated that the visual system adapts to the specific aberration pattern of an individual's eye. Alterations to this pattern can lead to...
Previous studies have demonstrated that the visual system adapts to the specific aberration pattern of an individual's eye. Alterations to this pattern can lead to reduced visual performance, even when the Root Mean Square (RMS) of the wavefront error remains constant. However, it is well-established that ocular aberrations are dynamic and can change with factors such as pupil size and accommodation. This raises an intriguing question: can the neural system adapt to continuously changing aberration patterns? To address this question, we measured the ocular aberrations in four subjects under various natural viewing conditions, which included changes in accommodative state and pupil size. We subsequently computed the associated Point Spread Functions (PSFs). For each subject, we examined the stability in the orientation of the PSFs and analyzed the cross-correlation between different PSFs. These findings were then compared to the characteristics of a distribution featuring PSF shapes akin to random variations. Our results indicate that the changes observed in the PSFs are not substantial enough to produce a PSF shape distribution resembling random variations. This lends support to the notion that neural adaptation is indeed a viable mechanism even in response to continuously changing aberration patterns.
Topics: Humans; Eye; Accommodation, Ocular; Face; Refraction, Ocular; Pupil
PubMed: 38280921
DOI: 10.1038/s41598-024-52612-4