Optometry and Vision Science最新文献

Significance: This study has shown a vibrotactile sensory substitution device (SSD) prototype, VibroSight, has the potential to improve functional outcomes (i.e., obstacle avoidance, face detection) for people with profound vision loss, even with brief familiarization (<20 minutes).

Purpose: Mobility aids such as long canes are still the mainstay of support for most people with vision loss, but they do have limitations. Emerging technologies such as SSDs are gaining widespread interest in the low vision community. The aim of this project was to assess the efficacy of a prototype vibrotactile SSD for people with profound vision loss in the face detection and obstacle avoidance tasks.

Methods: The VibroSight device was tested in a movement laboratory setting. The first task involved obstacle avoidance, in which participants were asked to walk through an obstacle course. The second was a face detection task, in which participants were asked to step toward the first face they detected. Exit interviews were also conducted to gather user experience data. Both people with low vision (n = 7) and orientation and mobility instructors (n = 4) completed the tasks.

Results: In obstacle avoidance task, participants were able to use the device to detect (p<0.001) and avoid (p<0.001) the obstacles within a significantly larger range, but were slower (p<0.001), when compared with without the device. In face detection task, participants demonstrated a great level of accuracy, precision, and sensitivity when using the device. Interviews revealed a positive user experience, although participants identified that they would require a lighter and compact design for real-world use.

Conclusions: Overall, the results verified the functionality of vibrotactile SSD prototype. Further research is warranted to evaluate the user performance after an extended training program and to add new features, such as object recognition software algorithms, into the device.

Significance: Loss of homeostasis and chronic inflammation result in ocular surface damage in dry eyes, which is also associated with corneal thinning in established cases. Yet, the correlation between corneal thickness and new cases of dry eyes remains inadequately supported by evidence.

Purpose: This study aimed to compare the central corneal thickness of new cases of dry eyes to that of age- and gender-matched controls.

Methods: A total of 45 dry eye patients were compared with 61 age- and gender-matched non-dry eye individuals. The Ocular Surface Disease Index (OSDI) questionnaire was used to evaluate symptoms, and the central corneal thickness was measured with a Nidek CEM-530 specular microscope. Patients were grouped based on disease severity (OSDI scores), and the clinical findings were compared between groups for slit-lamp examinations, Schirmer's I test, and tear film breakup time.

Results: The median age of patients was 25.0 (interquartile range [IQR], 20.0 to 32.0) and 27.0 (IQR, 20.0 to 32.0) years in the control and dry eye groups, respectively (p=0.63). The median (IQR) values of the OSDI scores, tear film breakup time scores, and Schirmer's test measurements in the control groups were 10.4 (8.3 to 10.4), 12.0 (11.0 to 14.0) seconds, and 16.0 (13.5 to 19.5) mm, respectively, which differed from the dry eye groups (p<0.0001). These values in the dry eye group were 29.1 (25.0 to 39.5), 4.0 (3.0 to 8.0) seconds, and 8.0 (3.5 to 11.0) mm, respectively. Patients with dry eyes had lower central corneal thickness than controls (p<0.01). The mean ± standard deviation central corneal thicknesses in patients with dry eyes and the control group were 520.3 ± 26.8 and 545.3 ± 18.8 μm, respectively.

Conclusions: The central corneal thickness in dry eyes was significantly reduced compared with the control group. These findings may be useful in monitoring and managing dry eyes and should be considered in intraocular pressure measurements and refractive surgical procedures.

Significance: An understanding of factors that affect the foveal avascular zone (FAZ) in healthy eyes may aid in the early identification of patients at risk of retinal pathology, thereby allowing better management and preventive measures to be implemented.

Purpose: The size and shape of the FAZ can change due to retinal diseases associated with oxidative stress, including diabetic retinopathy, glaucoma, and macular degeneration. This study aimed to assess the relationship, if any, between factors that may affect the superficial FAZ (i.e., vessel density, vessel perfusion, overweight/obesity) and possible links with macular pigment optical density in young, healthy participants.

Methods: One hundred thirty-nine participants aged 18 to 35 years were recruited to this cross-sectional study. The superficial FAZ area, foveal vascularity, and central macular thickness (CMT) were assessed using the Cirrus 5000. Health parameters, body mass index, trunk fat %, and macular pigment were analyzed to determine possible associations with the superficial FAZ.

Results: Mean FAZ area was 0.23 ± 0.08 mm2. Females had a significantly larger mean FAZ area than males (p=0.002). The FAZ area was positively correlated with body mass index (Pearson's r = 0.189, p=0.026). Significant correlates of the FAZ area in the multivariate model included vessel perfusion (central), CMT, and trunk fat %, collectively explaining 65.1% of the overall variability.

Conclusions: Study findings suggest that reduced vessel perfusion, thinner CMT, and higher trunk fat % are plausible predictors of a larger FAZ area in healthy Caucasian adults. Low macular pigment optical density was, however, not associated with increased FAZ size in young healthy eyes. Noninvasive optical coherence tomography angiography testing, in association with these predictors, may aid in the early detection and monitoring of retinal diseases associated with oxidative stress.

Significance: This is a review of the optics of various spectacle lenses that have been used in myopia control over the last 60 years, with emphasis on approximately the last 15 years.Myopia has become an increasing health problem worldwide, particularly in some East Asian countries. This has led to many attempts to slow its progression in children and reduce its endpoint value. This review is concerned with the optics of spectacle lenses for use in myopia control, from bifocal lenses to multisegment and diffusion optics lenses. Treatments are based on theories of the onset or progression of myopia. These include the hypotheses that eye growth and myopia in susceptible children may be stimulated by (1) poor accommodation response and the consequent hyperopic defocus with near vision tasks, (2) relative hyperopic peripheral refraction, and (3) high retinal image contrast as occurs in urban environments. Using spectacle lenses to slow myopia progression has a history of about 60 years. The review is laid out in approximately the order in which different types of lenses have been introduced: bifocals, conventional progressive addition lenses, undercorrection with single-vision lenses, specialized progressive addition lenses, defocus-incorporated multiple segments, diffusion optics, and concentric bifocals. In the review, some of the lenses are combined with an eye model to determine refractive errors for peripheral vision for the stationary eye and for foveal vision for the rotating eye. Numbers are provided for the reported success of particular designs in retarding myopia progression, but this is not an epidemiological paper, and there is no critical review of the findings. Some of the recent treatments, such as multiple segments, appear to reduce the eye growth and myopia progression by better than 50% over periods of up to 2 years.

Significance: Central corneal epithelial thinning associated with midperipheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet, the cellular mechanism governing the regional change in refractive power remains elusive.

Purpose: This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers.

Methods: A new human prototype of a polarization-dependent optical coherence microscope was developed to enable noncontact and noninvasive in vivo imaging of corneal epithelial cells in ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and midperipheral corneal locations in four ortho-k wearers and four spectacle wearers serving as controls.

Results: Polarization-dependent optical coherence microscope achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view of 0.5 × 0.5 mm 2 with an isotropic resolution of ~2.2 mm. The central epithelial thinning and midperipheral epithelial thickening were consistent across all ortho-k wearers. However, the inconsistency in their regional epithelial cell density highlighted a great variability in individual response to ortho-k treatment. There was no strong correlation between epithelial thickness and cell density, especially at the midperipheral cornea, in ortho-k participants.

Conclusions: This study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cells before and during ortho-k treatment to identify factors governing individual response to ortho-k treatment and ultimately inform the dynamics of epithelial cells taking place during the ortho-k treatment.