High resolution imaging of ultrafine bubbles in water by Atmospheric SEM-CL.

Various analytical methods such as high-resolution observation of ultrafine bubbles in water are required to clarify the mechanisms and interrelationships of various effects brought about by ultrafine bubbles. In this study, we used atmospheric scanning electron microscopy-cathodoluminescence (ASEM-CL) method for observing ultrafine bubbles in water. ASEM can observe samples in water, and the fine electron beam provides high spatial resolution. Furthermore, the gas in the bubble can be estimated from the CL emission spectrum. We have measured characteristics such as bubble size and particle number density. Also, the CL spectra has shown that the ultrafine bubbles contained nitrogen.

Investigation of the pathophysiology of the retina and choroid in Parkinson's disease by optical coherence tomography.

PURPOSE: The pathology of Parkinson's disease (PD) is suspected to affect the retina and choroid. We investigated changes in the retina and choroid of patients with PD using optical coherence tomography. METHODS: We examined 14 patients with PD and 22 patients without PD. Patients without PD had no ophthalmic disease other than cataracts. In addition, it was also confirmed that there was no neurodegenerative disease. The retinal nerve fiber layer, ganglion cell layer + inner plexiform layer, and choroidal thickness were compared between both groups. Additionally, the choroidal image was divided into the choroid area, luminal area, and interstitial area using the binarization method, and the area of each region and the percentage of luminal area in the choroid area were analyzed. RESULTS: Patients with PD had a significantly thinner ganglion cell layer + inner plexiform layer compared to those without PD. The choroid area, luminal area, and interstitial area were significantly decreased in patients with PD compared to those without PD. Seven patients with PD who were successfully followed up showed decreased retinal nerve fiber layer and interstitial area after 3 years. CONCLUSION: Autonomic nervous disorders and neurodegeneration in PD can cause thinning of the retina and choroid, as well as a reduction in the choroid area.

Posterior Vitreous Detachment in Normal Healthy Subjects Younger Than Age Twenty.

Purpose: To describe the initiation of posterior vitreous detachment (PVD) in the eyes of normal individuals, under 20 years of age, using wide-angle optical coherence tomography (OCT). Methods: This is an observational cross-sectional study. Montaged images of horizontal and vertical OCT scans were obtained in 63 healthy eyes of 35 consecutive subjects ranging in age from 4 to 17 years. Results: Forty-five eyes (71.4%) had obvious PVD, defined as a contiguous line of posterior cortical vitreous separated from the surface of the retina. Eighteen eyes (28.6%) had no PVD. The mean age of the individuals without PVD was significantly younger than those with PVD (P = 0.008). The spatial distribution of PVD initiation was highest in the superior quadrants, with the nasal, inferior, septum papillomaculae, and temporal quadrants following in descending order of frequency (P < 0.001). PVD was observed to begin anterior to the premacular liquefied lacuna, where the vitreous gel directly adheres to the vitreoretinal interface. In the majority of subjects (80.6%), PVD was initiated anterior to the vascular arcades. Conclusions: PVD can be observed by OCT to begin in the first and second decade of life. It begins in the mid-peripheral vitreous, most frequently in the superior quadrants anterior to the vascular arcades. In this study, all PVDs originated outside of the macular liquefied lacunae, where the vitreous gel adheres directly to the retina.

Differences in the Stimulus Accommodative Convergence/Accommodation Ratio using Various Techniques and Accommodative Stimuli.

PURPOSE: To investigate differences in the stimulus accommodative convergence/accommodation (AC/A) ratio using various techniques and accommodative stimuli, and to describe a method for determining the stimulus AC/A ratio. METHODS: A total of 81 subjects with a mean age of 21 years (range, 20-23 years) were enrolled. The relationship between ocular deviation and accommodation was assessed using two methods. Ocular deviation was measured by varying the accommodative requirement using spherical plus/minus lenses to create an accommodative stimulus of 10.00 diopters (D) (in 1.00 D steps). Ocular deviation was assessed using the alternate prism cover test in method 1 at distance (5 m) and near (1/3 m), and the major amblyoscope in method 2. The stimulus AC/A ratios obtained using methods 1 and 2 were calculated and defined as the stimulus AC/A ratios with low and high accommodation, respectively, using the following analysis method. The former was calculated as the difference between the convergence response to an accommodative stimulus of 3 D and 0 D, divided by 3. The latter was calculated as the difference between the convergence response to a maximum (max) accommodative stimulus with distinct vision of the subject and an accommodative stimulus of max minus 3.00 D, divided by 3. RESULTS: The median stimulus AC/A ratio with low accommodation (1.0 Δ/D for method 1 at distance, 2.0 Δ/D for method 1 at near, and 2.7 Δ/D for method 2) differed significantly among the measurement methods (P < 0.01). Differences in the median stimulus AC/A ratio with high accommodation (4.0 Δ/D for method 1 at distance, 3.7 Δ/D for method 1 at near, and 4.7 Δ/D for method 2) between method 1 at distance and method 2 were statistically significant (P < 0.05), while method 1 at near was not significantly different compared with other methods. CONCLUSIONS: Differences in the stimulus AC/A ratio value were significant according to measurement technique and accommodative stimuli. However, differences caused by measurement technique may be reduced by using a high accommodative stimulus during measurements.

[One-year longitudinal change in parameters of myopic school children trained by a new accommodative training device--uncorrected visual acuity, refraction, axial length, accommodation, and pupil reaction].

PURPOSE: School children with myopia were trained using a visual stimulation device that generated an isolated blur stimulus on a visual target, with a constant retinal image size and constant brightness. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and papillary reaction were measured to investigate the effectiveness of the training. SUBJECTS AND METHODS: There were 45 school children with myopia without any other ophthalmic diseases. The mean age of the children was 8.9 +/- 2.0 years (age range; 6-16)and the mean refraction was -1.56 +/- 0.58 D (mean +/- standard deviation). As a visual stimulus, a white ring on a black background with a constant ratio of visual target size to retinal image size, irrespective of the distance, was displayed on a liquid crystal display (LCD), and the LCD was quickly moved from a proximal to a distal position to produce an isolated blur stimulus. Training with this visual stimulus was carried out in the relaxation phase of accommodation. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and pupillary reaction were investigated before training and every 3 months during the training. RESULTS: Of the 45 subjects, 42 (93%) could be trained for 3 consecutive months, 33 (73%) for 6 months, 23 (51%) for 9 months, and 21 (47%) for 12 months. The mean refraction decreased by 0.83 +/- 0.56 D (mean +/- standard deviation) and the mean axial length increased by 0.47 +/- 0.16 mm at 1 year, showing that the training bad some effect in improving the visual acuity. In the tests of the dynamic accommodative responses, the latency of the accommodative-phase decreased from 0.4 +/- 0.2 sec to 0.3 +/- 0.1 sec at 1 year, the gain of the accommodative-phase improved from 69.0 +/- 27.0% to 93.3 +/- 13.4%, the maximum speed of the accommodative-phase increased from 5.1 +/- 2.2 D/sec to 6.8 +/- 2.2 D/sec and the gain of the relaxation-phase significantly improved from 52.1 +/- 26.0% to 72.7 +/- 13.7% (corresponding t-test, p < 0.005). No significant changes were observed in the pupillary reaction. CONCLUSION: The training device was useful for improving the accommodative functions and accommodative excess, suggesting that it may be able to suppress the progression of low myopia, development of which is known to be strongly influenced by environmental factors.

Training regimen involving cyclic induction of pupil constriction during far accommodation improves visual acuity in myopic children.

PURPOSE: Myopia in school-age children has become increasingly prevalent in industrialized countries, especially in Asia. A large population of school-age children still suffers from low visual acuity. We have developed a novel, safe and noninvasive training method to activate a pupillary constriction response during far accommodation that results in improved visual acuity. METHODS: Myopic children (n = 95) were treated for 3-minute sessions up to twice a week for 12-106 weeks. We stimulated quick cycles of near/far accommodation by displaying a visual object on a LCD screen and moving the screen in cycles from a near (25 cm) to a far (70 cm) point and back, while keeping the retinal projection size and brightness of the object constant. RESULTS: Mechanistically, we noted pupillary constriction upon far accommodation in trained myopic children, which was not seen in normal subjects or in untrained myopic children. Eighty five percent (52/61) of trained myopic right eyes with two sessions weekly experienced improved visual acuity (VA) by more than 0.1 logMAR units with an average improvement of 0.30 +/- 0.03 standard error of mean (SEM) logMAR units. With maintained training, most eyes' improved VA stayed almost constant, for more than 50 weeks in the case of 12 long trained subjects. CONCLUSIONS: This simple, short and safe accommodation training greatly improves the quality of vision in a large population suffering from refractive abnormalities.

[Influence of accommodative response and visual symptoms on visual display terminal adult operators with asthenopia through adequately corrected refractive errors].

PURPOSE: Application of adequate correction of refractory errors for the treatment of asthenopia of young visual display terminal (VDT) workers was evaluated from subjective complaints and the effect on accommodation dynamics (step response) before and after 6 months. METHODS: Young VDT workers who visited the clinic because of eye strain were consecutively selected. Fifteen workers who were under-corrected for myopia and three workers who were over-corrected for myopia were treated by "adequate correction of refractory errors" with spectacles or soft contact lenses. The adequate correction was defined as minimum convex lenses which could obtain visual acuity of 1.2 or better, similar to daily life conditions, without cyclopegia or fogging. The workers were in their 20's. Accommodative responses to step stimuli were recorded by infrared optometer, and questionnaires were filled out by the VDT workers concerning the severity (a severity rating in percent in five steps) of subjective symptoms (headache, dry eye, eye strain, and eye irritation). Spectacles or disposable contact lenses were prescribed for the workers for "adequate correction". Six months later, accommodative responses and subjective symptoms were evaluated and compared with under-or over-corrected conditions and adequate correction. RESULTS: In under-corrected workers, the adequate correction significantly improved complains i.e. headache, eye strain, eye tiredness (p < 0.005). Accommodative responses also improved in gain (%), maximum velocity (D/sec), and time of accommodation and relaxation (p < 0.05). Three over-corrected workers showed improvement of complains and also accommodative response in gain, maximum velocity, and time of accommodation and relaxation. CONCLUSIONS: Application of "adequate correction" to young VDT workers with asthenopia by using adequately corrected spectacles or soft contact lenses improved the asthenopia and accommodative dynamics.

Ischemic optic neuropathy associated with subarachnoid hemorrhage after rupture of anterior communicating artery aneurysm.

Two clinical cases in which ischemic optic neuropathy (ION) occurred after subarachnoid hemorrhage (SAH) are reported. Hemorrhage in the proximity of the optic chiasm was confirmed in 2 cases following rupture of an anterior communicating artery aneurysm. Optic disk atrophy with excavation and permanent visual field defect (altitudinal superior hemianopia) occurred in both cases. ION seems to occur in association with the optic nerve coincidental with the hyperdensity side of SAH on head CT scan. The incidence of ION appears to be attributable to an insufficient blood supply to arteries distributed in the posterior part of the optic nerve as a result of SAH.