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Showing papers on "Foveal published in 2007"


Journal ArticleDOI
TL;DR: Visual signals from the fovea are not essential for normal refractive development or the vision-induced alterations in ocular growth produced by form deprivation, and the peripheral retina, in isolation, can regulate emmetropizing responses and produce anomalous refractive errors in response to abnormal visual experience.
Abstract: Purpose Because of the prominence of central vision in primates, it has generally been assumed that signals from the fovea dominate refractive development. To test this assumption, the authors determined whether an intact fovea was essential for either normal emmetropization or the vision-induced myopic errors produced by form deprivation.

272 citations


Journal ArticleDOI
TL;DR: A representation of eye position is demonstrated in monkey primary somatosensory cortex, in the representation of the trigeminal nerve, near cells with a tactile representations of the contralateral brow, which represents the position of the eye in the head and not the angle of gaze in space.
Abstract: The cerebral cortex must have access to an eye position signal, as humans can report passive changes in eye position in total darkness, and visual responses in many cortical areas are modulated by eye position. The source of this signal is unknown. Here we demonstrate a representation of eye position in monkey primary somatosensory cortex, in the representation of the trigeminal nerve, near cells with a tactile representation of the contralateral brow. The neurons have eye position signals that increase monotonically with increasing orbital eccentricity from near the center of gaze, with directionally selectivity tuned in a Gaussian manner. All directions of eye position are represented in a single hemisphere. The signal is proprioceptive, because it can be obliterated by anesthetizing the contralateral orbit. It is not related to foveal or peripheral visual stimulation, and it represents the position of the eye in the head and not the angle of gaze in space.

222 citations


Journal ArticleDOI
TL;DR: The hypothesis that the ulnar fovea sign is a useful clinical maneuver to detect foveal disruptions and UT ligament tears is supported and represents 2 common sources of ulnar-sided wrist pain.
Abstract: Purpose Eliciting tenderness in the region of the ulnar fovea is a possibly useful clinical test for defining the source of ulnar-sided wrist pain. Until now, no reports of the clinical sensitivity and specificity of this test have been available. Based on anecdotal observations, a hypothesis was developed stating that ulnar fovea tenderness (positive "ulnar fovea sign") is sensitive and specific in detecting two ulnar-sided wrist conditions: foveal disruption of the distal radioulnar ligaments and ulnotriquetral (UT) ligament injuries. Methods The clinical records of 272 consecutive patients with wrist arthroscopy performed by the senior author from 1998 through to 2005 were reviewed. Relevant clinical and surgical data were abstracted. The ulnar fovea sign test is executed by pressing the examiner's thumb distally into the interval between the ulnar styloid process and flexor carpi ulnaris tendon, between the volar surface of the ulnar head and the pisiform. A positive ulnar fovea sign is designated when there is exquisite tenderness that the patient claims replicates their pain, with comparisons made with the contralateral side. Results There were a total of 90 foveal disruptions and 68 UT ligament injuries diagnosed during wrist arthroscopy. The ulnar fovea sign was positive in 156 patients. The sensitivity of the fovea sign in detecting foveal disruptions and/or UT ligament injuries was 95.2%. Its specificity was 86.5%. Conclusions The hypothesis stating that the ulnar fovea sign is a useful clinical maneuver to detect foveal disruptions and UT ligament tears is supported. The conditions represent 2 common sources of ulnar-sided wrist pain. The differentiation between the 2 conditions may be made clinically, where UT ligament tears are typically associated with a stable distal radioulnar joint and foveal disruptions are typically associated with an unstable distal radioulnar joint. Type of study/level of evidence Diagnostic II.

215 citations


Journal ArticleDOI
TL;DR: Contrary to traditional views, it is found that availability of attentional capacity determines neural representations related to unconscious processing of continuously suppressed stimuli in human primary visual cortex.

205 citations


Journal ArticleDOI
TL;DR: Investigating the correlation between integrity of the photoreceptor layer after resolution of macular oedema associated with branch retinal vein occlusion and final visual acuity found it to be associated with VA in resolved MO, and status of the third HRB before treatment might be predictive of visual outcome.
Abstract: Aim: To study the correlation between integrity of the photoreceptor layer after resolution of macular oedema (MO) associated with branch retinal vein occlusion (BRVO) and final visual acuity (VA), and to determine prognostic factors for visual outcome. Methods: We retrospectively studied 46 eyes from 46 patients with resolved MO secondary to BRVO, the foveal thickness of which was less than 250 µm at final observation. We assessed the status of the third high reflectance band (HRB) in the fovea using optical coherence tomography (OCT) at final observation, and studied OCT images taken at the initial visit in the hope of identifying a factor that would be prognostic of visual outcome. Results: No differences were found in initial VA or in foveal thickness between eyes with or without complete third HRB at final observation. However, final VA in eyes without a complete HRB was significantly poorer (p Conclusion: Integrity of the photoreceptor layer in the fovea is associated with VA in resolved MO, and status of the third HRB before treatment might be predictive of visual outcome.

141 citations


Journal ArticleDOI
TL;DR: In this paper, the authors showed that attention can selectively enhance neuronal responses and exclude external noise, but the neuronal computations that underlie these effects remain unknown, and that noise exclusion might result in altered spatial integration properties.
Abstract: Attention can selectively enhance neuronal responses and exclude external noise, but the neuronal computations that underlie these effects remain unknown. At the neuronal level, noise exclusion might result in altered spatial integration properties. We tested this proposal by recording neuronal activity and length tuning in neurons of the primary visual cortex of the macaque when attention was directed toward or away from stimuli presented in each neuron's classical receptive field. For cells with central-parafoveal receptive fields, attention reduced spatial integration, as demonstrated by a reduction in preferred stimulus length and in the size of the spatial summation area. Conversely, in cells that represented more peripheral locations, attention increased spatial integration by increasing the cell's summation area. This previously unknown dichotomy between central and peripheral vision could support accurate analysis of attended foveal objects and target selection for impending eye movements to peripheral objects.

126 citations


Proceedings Article
06 Jan 2007
TL;DR: This paper presents a novel method for identifying and tracking objects in multiresolution digital video of partially cluttered environments and uses a learned "attentive" interest map on a low resolution data stream to direct a high resolution "fovea".
Abstract: Human object recognition in a physical 3-d environment is still far superior to that of any robotic vision system. We believe that one reason (out of many) for this--one that has not heretofore been significantly exploited in the artificial vision literature--is that humans use a fovea to fixate on, or near an object, thus obtaining a very high resolution image of the object and rendering it easy to recognize. In this paper, we present a novel method for identifying and tracking objects in multiresolution digital video of partially cluttered environments. Our method is motivated by biological vision systems and uses a learned "attentive" interest map on a low resolution data stream to direct a high resolution "fovea." Objects that are recognized in the fovea can then be tracked using peripheral vision. Because object recognition is run only on a small foveal image, our system achieves performance in real-time object recognition and tracking that is well beyond simpler systems.

87 citations


Journal ArticleDOI
TL;DR: The prognostic value of foveal hypoplasia as assessed by OCT in young patients with albinism is superior to grades based on iris transillumination or macular transparency.

82 citations


Journal ArticleDOI
TL;DR: Anomalies in foveal anatomy by OCT may be a vestige of prematurity, appear to be independent of prior retinopexy, and can still be associated with excellent visual acuity.
Abstract: PURPOSE: To describe the optical coherence tomography (OCT) findings for patients with a history of retinopathy of prematurity (ROP). METHODS: Clinical records, fundus photographs, and OCT findings for consecutive patients aged 8 years and older who had a history of ROP were reviewed. The main outcome measures were best-corrected visual acuity, central foveal thickness (CFT), macular anatomy, and foveal contour by OCT. RESULTS: Twenty eyes of 12 patients (median age, 15 years) were studied. Median gestational age at birth was 25 weeks. Six eyes had received peripheral retinal ablation for threshold ROP. Median best-corrected visual acuity was 20/40 (range, 20/20 to counting fingers). CFT was >220 microm in 70% of eyes and >240 microm in 35% of eyes. In all eyes, foveal contour was abnormal, with foveal depression either absent (n = 7 [35%]) or shallow (n = 13 [65%]). Preservation of multiple inner retinal layers within the fovea was seen in 14 eyes (70%). Vitreomacular traction or subretinal fluid was not seen in any eye. CONCLUSIONS: Anomalies in foveal anatomy by OCT may be a vestige of prematurity, appear to be independent of prior retinopexy, and can still be associated with excellent visual acuity.

73 citations


Journal ArticleDOI
TL;DR: It is suggested that a range of stimuli, slightly varying in size, may all be processed by the same neural channel--the channel with the smallest receptive fields of the visual system, which can use different mechanisms for the discrimination of different test stimuli in the presence of particular surround.
Abstract: We describe several experiments on contour interactions and crowding effects at the resolution limit of the visual system. As test stimuli we used characters that are often employed in optometric practice for testing visual acuity: Landolt C's, Snellen E's, and rectangular gratings. We tested several hypotheses that have been put forward to explain contour interaction and crowding effects. In Experiment 1 and Experiment 2, Landolt C's were the test stimuli, and bars, or Landolt C's, or gratings served as distractors. In Experiment 1, we showed that neither scale invariance nor spatial frequency selectivity is a characteristic of foveal crowding effects. These results allowed us to conclude that mechanisms other than lateral masking contribute to observers' performance in 'crowded' tasks. R. F. Hess, S. C. Dakin, and N. Kappor (2000) suggested that the spatial frequency band most appropriate for target recognition is shifted by the surrounding bars to higher spatial frequencies that cannot be resolved by observers. Our Experiment 2 rejects this hypothesis as the experimental data do not follow theoretical predictions. In Experiment 3, we employed Snellen E's, both as test stimuli and as distractors. The masking functions were similar to those measured in Experiment 1 when the test Landolt C was surrounded by Landolt C's. In Experiment 4, we extended the range of test stimuli to rectangular gratings; same-frequency or high-frequency gratings were distractors. In this case, if the distracting gratings had random orientation from trial to trial, the critical spacing was twice larger than in the first three experiments. If the orientation of the distractors was fixed during the whole experiment, the critical spacing was similar to that measured in the first three experiments. We suggest that the visual system can use different mechanisms for the discrimination of different test stimuli in the presence of particular surround. Different receptive fields with different spatial characteristics can be employed. To explain why crowding effects at the resolution limit of the visual system are not scale invariant, we suggest that a range of stimuli, slightly varying in size, may all be processed by the same neural channel--the channel with the smallest receptive fields of the visual system.

70 citations


Journal ArticleDOI
TL;DR: Overall results showed depressed fMRI signal magnitude for amblyopic eyes compared with sound eyes, although a few subjects did not show this trend, and assessment of the spatial extent of activation using an ocular dominance index did show significantly larger interocular differences for both strabismics and anisometropes compared with control subjects for whom eye dominance was carefully defined.
Abstract: Purpose Although previous neuroimaging efforts clearly indicate visual cortical dysfunction in adults with amblyopia, the extent of abnormalities remains unclear. Methods This functional magnetic resonance imaging (fMRI) study directly compared activity in visual cortex produced by monocular stimulation in 18 adults (six esotropic strabismics, six anisometropes, and six controls). Measures were made in three cortical regions-of-interest, individually defined using standard retinotopic mapping techniques in the nonamblyopic eye, corresponding to extrafoveal V1, extrafoveal V2, and the foveal representation at the occipital pole. Fixation stability was monitored and found not to differ significantly between subject groups. Results Overall results showed depressed fMRI signal magnitude for amblyopic eyes compared with sound eyes, although a few subjects did not show this trend. Assessment of the spatial extent of activation using an ocular dominance index did show significantly larger interocular differences for both strabismics and anisometropes compared with control subjects for whom eye dominance was carefully defined. In addition, both amblyopic groups showed less cortical area able to be significantly driven by either eye. The magnitude of these effects was equivalent in V1, V2, and the foveal representation, as well as between amblyopic groups. No difference was detected in the strength of signal from the nasal versus temporal retina in either amblyopic group. Conclusions Asymmetries in magnitude of monocular activation do occur in subjects with amblyopia, but these basic measures are limited in terms of sensitivity for mild to moderate amblyopia and for specificity between subtypes.

Journal ArticleDOI
TL;DR: The results showed that foveal splitting effects in visual word recognition were observed in N1 the earliest, and could extend far enough to interact with the sex of the reader as revealed in N350.

Journal ArticleDOI
TL;DR: Using fMRI in healthy subjects, the authors demonstrated the existence of two systems, differently modulated by the two reaching conditions, that are engaged in reaching to targets in the central and peripheral visual field.
Abstract: Lesions of the posterior parietal cortex in humans can produce a specific disruption of visually guided hand movements termed optic ataxia. The fact that the deficit mainly occurs in peripheral vision suggests that reaching in foveal and extrafoveal vision relies on two different anatomical substrates. Using fMRI in healthy subjects, the authors demonstrated the existence of two systems, differently modulated by the two reaching conditions. Reaching in central vision involves a restricted network, including the medial intraparietal sulcus (mIPS) and the caudal part of the dorsal premotor cortex (PMd). Reaching in peripheral vision engages a more extensive network, including the parieto-occipital junction (POJ). Interestingly, POJ corresponds to the site of the lesion overlap that the authors recently found to be responsible for optic ataxia. These two sets of results converge to show that there is not a unique cortical network for reaching control but instead two systems engaged in reaching to targets in the central and peripheral visual field.

Journal ArticleDOI
TL;DR: The finding of substantial interaction between first- and second-order stimuli suggests that the processing of these stimuli is not independent at the stage of processing at which crowding occurs, and suggests that these stimuli are processed by separate pathways.
Abstract: Evidence that the detection of first- and second-order visual stimuli is processed by separate pathways abounds. This study asked whether first- and second-order stimuli remain independent at the stage of processing where crowding occurs. We measured thresholds for identifying a first-order (luminance defined) or second-order (contrast defined) target letter in the presence of two second- or first-order flanking letters. For comparison, we also measured thresholds when the target and flanking letters were all first or second order. Contrast of the flankers was 1.6 times their respective contrast thresholds. Measurements were obtained at the fovea and 10- in the lower visual field of four normally sighted observers. Two observers were also tested at 10- nasal visual field. As expected, in both the fovea and periphery, the magnitude of crowding (threshold elevation) was maximal at the closest letter separation and decreased as letter separation increased. The magnitude of crowding was greater for second- than for first-order target letters, independent of the order type of flankers; however, the critical distance for crowding was similar for first- and second-order letters. Substantial crossover crowding occurred when the target and flanking letters were of different order type. Our finding of substantial interaction between first- and second-order stimuli suggests that the processing of these stimuli is not independent at the stage of processing at which crowding occurs.

Journal ArticleDOI
TL;DR: Nanophthalmic patients rarely have best-corrected visual acuity (BCVA) better than 20/40 at any point in their lives, even with an absence of known complications, such as uveal effusion or glaucoma.

Journal ArticleDOI
TL;DR: The results demonstrate that interhemispheric communication is required for foveal word recognition and asymmetric representations of language and processes of interhemisphere transfer should be taken into account in theoretical models of visual word recognition to ensure neurological plausibility.
Abstract: The left cerebral hemisphere is dominant for language processing in most individuals. It has been suggested that this asymmetric language representation can influence behavioral performance in foveal word-naming tasks. We carried out two experiments in which we obtained laterality indices by means of functional imaging during a mental word-generation task, using functional transcranial Doppler sonography and functional magnetic resonance imaging, respectively. Subsequently, we administered a behavioral word-naming task, where participants had to name foveally presented words of different lengths shown in different fixation locations shifted horizontally across the screen. The optimal viewing position for left language dominant individuals is located between the beginning and the center of a word. It is shifted toward the end of a word for right language dominant individuals and, to a lesser extent, for individuals with bilateral language representation. These results demonstrate that interhemispheric communication is required for foveal word recognition. Consequently, asymmetric representations of language and processes of interhemispheric transfer should be taken into account in theoretical models of visual word recognition to ensure neurological plausibility.

Journal ArticleDOI
TL;DR: It is concluded that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations.
Abstract: Amblyopia is a developmental visual disorder associated with loss of monocular acuity and sensitivity as well as profound alterations in binocular integration Abnormal connections in visual cortex are known to underlie this loss, but the extent to which these abnormalities are regionally or retinotopically specific has not been fully determined This functional magnetic resonance imaging (fMRI) study compared the retinotopic maps in visual cortex produced by each individual eye in 19 adults (7 esotropic strabismics, 6 anisometropes and 6 controls) In our standard viewing condition, the non-tested eye viewed a dichoptic homogeneous mid-level grey stimulus, thereby permitting some degree of binocular interaction Regions-of-interest analysis was performed for extrafoveal V1, extrafoveal V2 and the foveal representation at the occipital pole In general, the blood oxygenation level-dependent (BOLD) signal was reduced for the amblyopic eye At the occipital pole, population receptive fields were shifted to represent more parafoveal locations for the amblyopic eye, compared with the fellow eye, in some subjects Interestingly, occluding the fellow eye caused an expanded foveal representation for the amblyopic eye in one early–onset strabismic subject with binocular suppression, indicating real-time cortical remapping In addition, a few subjects actually showed increased activity in parietal and temporal cortex when viewing with the amblyopic eye We conclude that, even in a heterogeneous population, abnormal early visual experience commonly leads to regionally specific cortical adaptations

Journal ArticleDOI
TL;DR: In this paper, the authors used an adapted version of the Reicher-Wheeler paradigm to test the split fovea theory and found that a minimal amount of graphic input is necessary to induce a P1 event.

Journal ArticleDOI
TL;DR: An eye fixation monitor that detects the fovea by its radial orientation of birefringent nerve fibers is developed and reported, and a linear transformation to obtain horizontal and vertical eye position coordinates from the four photodetector signals is proposed.
Abstract: We recently developed and reported an eye fixation monitor that detects the fovea by its radial orientation of birefringent nerve fibers The instrument used a four-quadrant photodetector and a normalized difference function to check for a best match between the detector quadrants and the arms of the bow-tie pattern of polarization states surrounding the fovea This function had a maximum during central fixation but could not tell where the subject was looking relative to the center We propose a linear transformation to obtain horizontal and vertical eye position coordinates from the four photodetector signals, followed by correction based on a priori calibration information The method was verified on both a computer model and on human eyes The major advantage of this new eye-tracking method is that it uses true information coming from the fovea, rather than reflections from other structures, to identify the direction of foveal gaze

Journal ArticleDOI
TL;DR: OCT and the foveal cone ERG together appear to be sufficient to identify the basis for visual acuity loss in these patients, and may result from photoreceptor loss or fveal malfunction without photorecept loss, which are indicators of occult macular dystrophy.

01 Jan 2007
TL;DR: An architecture for reactive visual analysis of dynamic scenes that responds to unique visual stimuli and is capable of top-down modulation of attention towards regions and cues relevant to tasks is developed.
Abstract: We develop an architecture for reactive visual analysis of dynamic scenes. We specify a minimal set of system features based upon biological observations. We implement feature on a processing network based around an active stereo vision mechanism. Active rectification and mosaicing allows static stereo algorithms to operate on the active platform. Foveal zero disparity operations permit attended object extraction and ensures coordinated stereo fixation upon visual surfaces. Activedynamic inhibition of return, and task dependent biasing result in a flexible, preemptive and retrospective system that responds to unique visual stimuli and is capable of top-down modulation of attention towards regions and cues relevant to tasks.

Journal ArticleDOI
TL;DR: The objective was to assess the predictive value of optical coherence tomography mapping of retinal thickness and intraretinal morphological changes after macular grid for diffuse diabetic macular oedema (DMO).
Abstract: Purpose: To assess the predictive value of optical coherence tomography (OCT) mapping of retinal thickness and intraretinal morphological changes after macular grid for diffuse diabetic macular oedema (DMO). Methods: We carried out a prospective, non-controlled, case series study, in which 28 consecutive eyes with previously untreated diffuse DMO underwent fundus photography and OCT at baseline and at 1, 3 and 6 months after treatment. Results: Macular photocoagulation was followed by a significant reduction in retinal thickness in the foveal centre () 80 lm) and in the foveal subfield () 65 lm) from baseline to 6 months (p 0.05). The relative decrease in retinal thickness at 6 months was highest in the foveal centre () 22%), followed by the foveal region () 18%), the inner parafoveal region () 8%), and the outer parafoveal region () 2%). Thus, the effect of photocoagulation on retinal thickness decreased with increasing eccentricity (p < 0.025). Overall, there was no statistically significant change in best corrected visual acuity (BCVA) between baseline and follow-up (p < 0.05), but changes in foveal subfield thickness and changes in VA were highly correlated (r = 0.66, p < 0.0001). Visual outcome (final BCVA) and final foveal subfield thickness at 6 months were correlated with the pattern of intraretinal morphological changes at baseline (Spearman’s correlation coefficient r = ) 0.41, p = 0.03 and r = 0.45, p = 0.02, respectively). In addition, visual outcome (final BCVA) and final foveal subfield thickness at 6 months were correlated with baseline foveal thickness (Spearman’s correlation coefficient (r = ) 0.37, p = 0.05 and r = 0.5, p = 0.01, respectively). Conclusions: It seems that the 1-month time-point after macular laser treatment is a critical point for establishing the outcome of this modality of management of DMO. Baseline OCT mapping of intraretinal fluid accumulation patterns and foveal thickness can help to predict the final visual outcome and final foveal thickness, but not the absolute change in either of these parameters after macular laser therapy.

Journal ArticleDOI
TL;DR: A single intravitreal bevacizumab injection provides short-term improvement in visual acuity and foveal detachment associated with IPT and should be followed by further studies to evaluate the long-term effects on retinal structure and function.

Proceedings ArticleDOI
05 Aug 2007
TL;DR: In this paper, a novel technique that combines eye tracking with subtle image-space modulation to direct a viewer's gaze about a digital image is presented, which exploits the fact that our peripheral vision has very poor acuity compared to our foveal vision.
Abstract: This article presents a novel technique that combines eye-tracking with subtle image-space modulation to direct a viewer's gaze about a digital image. We call this paradigm subtle gaze direction. Subtle gaze direction exploits the fact that our peripheral vision has very poor acuity compared to our foveal vision. By presenting brief, subtle modulations to the peripheral regions of the field of view, the technique presented here draws the viewer's foveal vision to the modulated region. Additionally, by monitoring saccadic velocity and exploiting the visual phenomenon of saccadic masking, modulation is automatically terminated before the viewer's foveal vision enters the modulated region. Hence, the viewer is never actually allowed to scrutinize the stimuli that attracted her gaze. This new subtle gaze directing technique has potential application in many areas including large scale display systems, perceptually adaptive rendering, and complex visual search tasks.

Journal ArticleDOI
TL;DR: Spatial attention modulates the activity of inferior parietal neurons, which may have different roles in the shift of attention preceding motor behaviors and may underlie shifts in parietal retinotopic maps observed with intrinsic optical imaging.
Abstract: Spatial attention modulates the activity of inferior parietal neurons. A statistically rigorous approach to classical retinotopic mapping was used to quantify the receptive fields of area 7a neurons under two attentional conditions. Measurements were made with retinal stimulation held constant and the locus of attention manipulated covertly. Both tasks required central fixation but differed in the locus of covert attention (either on the center fixation point, or on a peripheral square target in one of 25 locations). The neuron's identity over the recording session was confirmed using chaos theory to characterize unique temporal patterns. Sixty-six percent of the neurons changed prestimulus activity based on task state. Retinotopic mapping showed no evidence for foveal sparing. Attentional factors influenced visual responses for ∼30% of the neurons. Two types of modulation were equally observed. One group of cells had a multiplicative scaling of response, with equal instances of enhancement and suppression. A second group of cells had a complex interaction of visual and attentional signals, such that spatial tuning was subject to a non-linear modulation across the visual field based on attentional constraints. These two cell groups may have different roles in the shift of attention preceding motor behaviors and may underlie shifts in parietal retinotopic maps observed with intrinsic optical imaging.

Journal ArticleDOI
TL;DR: In this article, the Humphrey visual field analyzer central 30-2 foveal threshold test for best-corrected visual acuity was evaluated and found to provide a reliable estimate.

Journal ArticleDOI
TL;DR: A maximum a posterior probability zero disparity filter (MAP ZDF) ensures coordinated stereo fixation upon an arbitrarily moving, rotating, re-configuring hand, performing marker-less pixel-wise segmentation of the hand.

Journal ArticleDOI
TL;DR: This study aimed to evaluate foveal function, using three different methods, in children treated for monocular amblyopia with mixed results.
Abstract: PURPOSE: This study aimed to evaluate foveal function, using three different methods, in children treated for monocular amblyopia. METHODS: A sample of 24 otherwise healthy children with treated amblyopia and an age-matched control group of 25 healthy children were examined for best corrected visual acuity (BCVA) using a standard decimal (KM) chart and the computerized TriVA method at 50% and 10% contrasts. Foveal function was also measured with the rarebit fovea test (RFT), which is included in the rarebit perimetry program package. This test uses very small and bright dots against a dark background. The result is expressed as mean hit rate (MHR). RESULTS: Amblyopic eyes showed significantly lower BCVA when evaluated with the KM chart and with the TriVA test at different contrast levels, compared with both fellow eyes and control eyes. No statistically significant difference between amblyopic and fellow eyes was found when foveal function was evaluated with the RFT (median MHRs 91.5% and 94.5%, respectively), although results for both amblyopic and fellow eyes were statistically lower than those of the control group (median MHR 97%) (p = 0.001 and p = 0.046, respectively). This might indicate that the RFT provides different information about foveal function than conventional VA tests. CONCLUSIONS: The findings in the current study accord with those of other studies reporting abnormalities in the fellow eyes of previously treated amblyopic patients. These findings may reflect a general disturbance in the visual system rather than a monocular adaptation to refractive error or ocular motor disturbance.

Journal ArticleDOI
TL;DR: A case selection algorithm to assess suitability for macular translocation for subfoveal neovascular membrane (CNV) secondary to age‐related macular degeneration and surgical outcomes as selected by the algorithm is proposed.
Abstract: Purpose: We propose a case selection algorithm to assess suitability for macular translocation for subfoveal neovascular membrane (CNV) secondary to age-related macular degeneration. The algorithm is based on preoperative assessment of residual foveal function, as assessed by a slit-lamp fixation task and duration of visual loss, in patients with poor acuity. We validate our slit-lamp fixation task against an objective analysis (Nidek MP-1 Microperimetry) and proceed to examine surgical outcomes as selected by the algorithm. Methods: A prospective series of 27 consecutive patients with CNV underwent translocation at Moorfields Eye Hospital, London between May 2003 and May 2006. Results: Validation of the slit-lamp fixation task revealed 100% concordance in classification of fixation between the slit-lamp task and the microperimeter. At an average follow up of 12.2 months, the mean Early Treatment of Diabetic Retinopathy Study distance acuity improved from logMAR 0.88 to 0.68 (P < 0.03). Sixty-six per cent of patients achieved an acuity of ≤logMAR 0.8 (6/30), 22% an acuity of ≤logMAR 0.3 (6/12) and 33% gained three lines of acuity. The mean MN Read reading acuity improved from logMAR 1.23 to 0.91 (P < 0.01). Forty-four per cent of patients achieved an acuity of ≥logMAR 0.7 (N10), 15% an acuity of ≥logMAR 0.4 (N5) and 44% gained three lines of acuity. Discussion: We have demonstrated a simple case selection algorithm that is based on residual foveal function and suggests good outcomes. The strongest indicators of foveal function are fixation characteristics and duration of visual loss. In contrast to previous studies, our algorithm suggests good outcomes independently of preoperative visual acuity and CNV characteristics.

Journal ArticleDOI
TL;DR: The results highlight the role of the left hemisphere in linguistic analysis and point out possible limitations of foveal stimulus presentation for drawing conclusions about natural reading.