Practicing certain visual tasks leads, as a result of a process termed ''perceptual learning,'' to a significant improvement in performance. Learning is specific for basic stimulus features such as local orientation, retinal location, and eye of presentation, suggesting modification of neuronal processes at the primary visual cortex in adults. It is not known, however, whether such low-level learning affects higher-level visual tasks such as recognition. By systematic low-level training of an adult visual system malfunctioning as a result of abnormal development (leading to amblyopia) of the primary visual cortex during the ''critical period,'' we show here that induction of low-level changes might yield significant perceptual benefits that transfer to higher visual tasks. The training procedure resulted in a 2-fold improvement in contrast sensitivity and in letter-recognition tasks. These findings demonstrate that perceptual learning can improve basic representations within an adult visual system that did not develop during the critical period.A mblyopia is characterized by several functional abnormalities in spatial vision (for reviews see refs. 1-4), including reductions in visual acuity (VA), contrast-sensitivity function (CSF), and vernier acuity as well as spatial distortion (5), abnormal spatial interactions (6, 7), and impaired contour detection (8,9). In addition, amblyopic individuals suffer from binocular abnormalities such as impaired stereoacuity and abnormal binocular summation. The visual deficiencies are thought to be irreversible after the first decade of life (10-12), by which time the developmental maturation window has been terminated. The loss of vision is thought to result from abnormal operation of the neuronal network within the primary visual cortex, particularly of orientation-selective neurons and their interactions (13). The perceptual learning procedure described in this study was designed to train this network by efficiently stimulating these neuronal populations and effectively promoting their spatial interactions.Spatial interactions in human vision can be probed by contrast detection of a localized target in the presence of flankers (Fig. 1). These experiments show that the contrast threshold of a foveal Gabor signal (GS) is reduced in the presence of cooriented and coaligned (collinear) high-contrast GS flankers (14-18). The excitatory interaction is range-dependent and is maximal for target-flanker separation of approximately three times the GS wavelength. Smaller separations can raise the target threshold, depending on flanker contrast and phase (19). Singleunit recordings suggest that the underlying mechanisms reside within the primary visual cortex (20,21). Neuronal responses in the visual cortex are tuned for location, orientation, and spatial frequency. Recent evidence from studies in the cat and the monkey (20,(22)(23)(24)(25) shows that neuronal responses in the primary visual cortex are modulated by remote image parts, with both excitatory and inhibitory effects observ...

Recent studies have shown that perceptual learning has the potential to treat amblyopia. In this study we tested whether a recent perceptual learning technique that improved visual functions in adults can be applied to improve the vision of children after the conventional treatment of patching has failed. A prospective clinical pilot study was carried out in children who were non-compliant with patching or in whom patching had failed despite good compliance. Each child underwent a complete eye examination before and after treatment. The treatment was based on a perceptual learning technique that was similar to the adult study [Polat, U., Ma-Naim, T., Belkin, M., & Sagi, D. (2004). Improving vision in adult amblyopia by perceptual learning. Proceedings of the National Academy of Sciences of the United States of America, 101(17), 6692-6697]. Between blocks, children played a computer game to engage and maintain their attention in order to increase compliance. Each child received two treatment sessions a week, with a total of not more than 40 sessions. Each session lasted for about 1h and included a total practice time of about 30min. The age of the children (n=5) was between 7 and 8years (mean 7.3years). For the whole group, the average improvement in visual acuity was 1.5 Snellen lines or 2.12 ETDRS lines. The training improved the contrast sensitivity, which reached the normal range after treatment. Thus, the perceptual learning technique can be successfully used to treat children with amblyopia even after the conventional treatment of patching fails.

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Adults with amblyopia were recently shown to perform abnormally in tasks requiring integration of local features into global percepts. Moreover, spatial interactions in amblyopic patients, though often found to be abnormal, showed marked variability. Here we measured collinear lateral interactions using Gabor patches in a large number of amblyopic (N=75) and normal subjects (N=25), testing four spatial frequencies (1.5, 3, 6, 9 cpd). We used the lateral masking paradigm, in which the contrast-detection threshold is measured in the presence of high-contrast flankers at different distances from a central target. Whereas in normal subjects spatial interaction patterns were evident across all spatial frequencies, amblyopic subjects showed abnormal spatial interactions and increasing deficiencies with increasing spatial frequencies. These abnormalities depended on the axis of astigmatism (in meridional amblyopia) and were more pronounced in strabismic than in anisometropic amblyopia. Spatial interactions were independent on the contrast-detection thresholds. Thus, adults with amblyopia might perform as well as normal observers for some stimulus parameters and abnormally for others. Our results indicate a close relationship between abnormal visual input to the visual cortex during development and abnormal functionality of the collinear spatial interactions in adults with amblyopia.

Our findings of elevated IOP emphasize the need for prophylactic treatment (medical or combined cataract and glaucoma surgery) to prevent IOP spikes in high-risk patients.

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Background This study is aimed to evaluate the clinical approach of non-pediatric ophthalmologists, working in community-based clinics towards Pediatric Patients and their management including referral rates to Pediatric Ophthalmologists and Orthoptists. Methods an online survey was sent to all community ophthalmologists through national society and social media platforms. The questionnaire included questions regarding the responders’ professional experience as well as regarding the responders’ approach to children younger than 8 years, and the level of confidence in 4 main aspects of children’s management and referral rates. Results 93 physicians working as general ophthalmologists completed the questionnaire. Most respondents have been in practice for over 10 years (64/93, 68.8%) and over two-thirds were also hospital affiliated (65/93, 69.1%). The responders estimated on average that 35.1 ± 29.6% of patients under 8 years of age are referred for a consult to a pediatric ophthalmologist The level of confidence of three aspects unique to Pediatric Ophthalmology; cycloplegic refraction, strabismus evaluation, and prescribing glasses were significantly lower ( p < 0.01) than confidence in performing a basic eye exam. Conclusions many Ophthalmologists do not feel fully capable or experienced to perform the appropriate tests for the pediatric population, especially during the critical timeframe, before 8 years of age. The very high rate of referrals stands in contradiction to the reported low rate of eye pathologies in the pediatric population. These findings suggest that more pediatric-specific training is needed to improve the physician’s skills to perform a comprehensive evaluation of pediatric patients in order to reduce the referral burden.

Continuous circular capsulorhexis (CCC) is the preferred technique for removal of the anterior capsule during cataract surgery(1) due to this technique assuring accurate centration ofthe intraocular lens. During modem cataract surgery, especially with small or foldable intra ocular lenses, centration ofthe lens is obligatory(2). Radial tears at the margin of an anterior capsulotomy may be associated with the exit of at least one loop of an intraocular lens out of the capsular bag ("pea pod" effect) and its subsequent decentration. The anterior capsule is more likely to remain intact if the continuous circular capsulorhexis (CCC) technique is used (3).Although manual capsulorhexis is an ideal anterior capsulectomy technique for adults, many ophthalmologists are still uncomfortable with it and find it difficult to perform, especially in complicated cases such as these done behind small pupil, cataract extraction in children and pseudoexfoliation syndrome. We have developed a technique using a CO2 laser system for safe anterior capsulotomy and tested it in animal eyes. Materials and methodsThe laser used in these experiments was a DC excited CO2 Laser.(Kaplan PenduLaser 1 1 5, OPTOMEDIC Ltd. Or-Yehuda ISRAEL). This laser has output power of 5W to 15W. It can be operated either in continuous (CW) mode or pulsed, 1 p.p.s. -10 p.p.s. mode. Pulse width is 5Oms for all pulse rates. The output radiation (wavelength 1O.55m -1O.65tm) was delivered to the tissue by means of an articulated arm, (2 or 3 mirrors). A hand piece, with a f= 125mm ZnSe lens, was attached to the articulated arm. A 1 7G ( O.D. = 1.4mm), 50mm long stainless steel needle with a 45 degrees mirror at the distal end was added to the hand-piece. Through the needle both laser radiation and continuos flow of air were delivered to the anterior chamber. The air 196 SPIE Vol. 3246 • 0277-786X/98/$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/29/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx