Visual Fields

To investigate the relationship between the microstructure of β-zone peripapillary atrophy (PPA) and the subsequent visual field (VF) progression in eyes with primary open-angle glaucoma (POAG), including highly myopic eyes. Retrospective cohort study. A total of 129 patients with POAG who had been followed up for a minimum of 2 years and had undergone at least 5 reliable standard automated perimetry tests after spectral-domain (SD) optical coherence tomography (OCT) examination. β-Zone PPA was evaluated from 3 SD OCT scans centered on the optic disc. Upper and lower scans were defined as scans at 30° above and below the horizontal scan, respectively. From 3 scans of each eye, β-zone PPA was classified as PPA+BM or PPA-BM on the basis of the presence or absence of Bruch's membrane (BM), respectively. Eyes were classified into 3 groups according to the horizontal scan images: group A (only PPA+BM), group B (both PPA+BM and PPA-BM), and group C (only PPA-BM). Factors associated wi...

Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) "spike-less" periods. We sho...

Background: Cataract is the leading cause of avoidable blindness in developing world, including India. The objective of this study is to measure the changes in quality of life (VRQoL) after cataract surgery and identify the predictors of an improvement in these outcomes. Methods: A multi-center prospective, longitudinal cohort study was conducted. At baseline patients aged ≥18 years with first-eye cataract were interviewed about VRQoL. Six months" later participants were re-interviewed at their residences. Multiple classification analysis (MCA) was performed to assess the variation in the intensities of mean change scores for general function, psychosocial impact and visual function with select factors. Results: The six-month follow-up rate was 87.3%. There was a significant improvement in visual acuity and VRQoL post-surgery. The mean general function, psychosocial impact and visual function scores were 34.6 (SD 10.9), 10.5 (SD 3.7) and 8.4 (SD 2.2) in the baseline and 15 (SD 5.5), 5 (SD 2.2) and 4.4 (SD 1.6) in the follow-up assessments, respectively. In MCA, patients prescribed spectacles post-surgery (β 0.137) and those from rural backgrounds (β 0.137) had the most impact on general function. Patients with complete follow-up visits had a relatively higher effect on the psychosocial impact (β 0.084) whereas patients from rural background and men had the most impact on the visual function scores (β 0.102 and 0.076) respectively. Conclusions: Cataract surgery is associated with meaningful improvements in VRQoL in general. The determinants of better VFQoL include regular and complete patient follow-up visits and prescription and provision of spectacles post-surgery.

Many older adults eventually experience difficulty in everyday visual activities, prompting them to consult with an eye care specialist. In some cases, a thorough examination may reveal no clinical basis for these difficulties. New techniques for evaluating age-related declines in visual function have substantiated the existence of deficits in visual attention that are not adequately captured by standard clinical measures, and which are predictive of real world problems in driving and mobility. These new techniques may serve an important function in guiding the diagnosis, and treatment of those older adults experiencing functional visual problems.

Background: Glaucoma is a progressive optic neuropathy and a leading cause of irreversible blindness worldwide. Hypothyroidism has been proposed as a potential risk factor for glaucomatous optic nerve damage; however the association remains controversial. This research explores the possible connection between hypothyroidism and glaucomatous alterations in the head of optic nerve. The research was conducted in the Department of Ophthalmology, Teerthanker Mahaveer Medical College and research centre in Moradabad. Materials and Methods: A case-control study design was employed, involving 150 patients with hypothyroidism and 150 age and gender-matched nonhypothyroid controls. Participants were evaluated for visual acuity (UCVA and BCVA), intraocular pressure changes in the optic disc, cup to disc ratio (CDR), Retinal Nerve Fiber Layer (RNFL) thickness and perimetry for visual field impairment. Results: No significant differences were observed in the average age or gender distribution and the UCVA and BCVA measurements between the hypothyroid patients and the control group. Average IOP was significantly higher in hypothyroid patients compared to controls (19.2 ± 3.5 mmHg vs 16.8 ± 2.9 mmHg; p < 0.01). Mean RNFL thickness was significantly reduced in the hypothyroid group (82.4 ± 12.7 µm vs 90.3 ± 10.5 µm; p < 0.01). The mean CDR was significantly greater in cases (0.55 ± 0.15 vs 0.48 ± 0.12; p < 0.05). Visual field defects were more frequent among hypothyroid patients (8.6% vs 4.6%; p < 0.05). Glaucoma prevalence was significantly higher in the hypothyroid group (10.67%) compared to controls (4.67%) (p = 0.046). Conclusion: The study identified a statistically significant link between glaucoma and hypothyroidism. These findings suggest that patients with thyroid disorders should undergo routine glaucoma screening to facilitate early detection and reduce the risk of vision impairment.

Peripheral vision is characterized in part by poor spatial resolution and impaired visual performance, particularly when the object is surrounded by flanking elements, a phenomenon popularly known as ''crowding''. Crowding scales with eccentricity irrespective of the target size, both in terms of magnitude and spatial extent, which is determined by varying the target-flanker separation. However, the extent to which crowding depends upon the flanking stimuli parameters alone without separating target and flankers is poorly understood. In the present study, we investigated the effect of flanking stimulus parameters on crowding in orientation and contrast discrimination tasks using closely located ''chain'' lateral Gabor stimuli in order to enhance our understanding of the underlying mechanisms of crowding in peripheral vision. We found a strong configural effect on crowding in both orientation and contrast discrimination tasks, with reduced crowding when the flanker parameters enhanced the target salience and increased crowding when the flankers were perceptually grouped with the target. While in orientation discrimination crowding was dependent on eccentricity, and in contrast discrimination it was dependent on flanker contrast and eccentricity, crowding showed little dependence on the number of flankers in either task. We conclude that crowding in peripheral orientation and contrast discrimination is configuration specific, which can be reduced without alterations to the target-flanker separation and that crowding is a combination of low-level as well as high-level cortical processing.

To determine visual outcome including the occurrence of radiation induced optic neuropathy (RION) as well as tumor control after fractionated stereotactic radiation therapy (FSRT) of benign anterior skull base meningiomas or pituitary adenomas. Thirty-nine patients treated with FSRT for anterior skull base meningiomas and 55 patients treated with FSRT for pituitary adenomas between January 1999 and December 2009 with at least 2 years follow-up were included. Patients were followed up prospectively with magnetic resonance imaging scans, visual acuity and visual field examinations. RION was found in four (10 %) patients with anterior skull base meningiomas and seven patients (13 %) with pituitary adenomas. The five-year actuarial freedom from 25 % RION visual field loss was 94 % following FSRT. Actuarial 2-, 5-and 10-year tumor control rates were 100, 88.4 and 64.5 % for anterior skull base meningiomas and 100, 98.2 and 94.9 % for pituitary adenomas, respectively. Patients with an impaired visual field function pre-FSRT were more likely to experience worsened function (p = 0.016). We found that RION, was a relatively uncommon event, in a large prospective cohort of patients that were systematically monitored following FSRT of benign anterior skull base tumors. Long term tumor control was favorable, especially for pituitary adenomas.

The macula is essential for visual functioning and is known to be affected even in early glaucoma. However, little is currently understood about the prevalence and nature of central vision loss in early glaucoma. To determine the prevalence and characteristics of visual field (VF) defects in the central 10° in glaucoma suspects and patients with mild glaucoma using a prospective design. This prospective observational cohort study was conducted at an outpatient glaucoma specialty clinic. One hundred eyes from 74 patients with glaucomatous optic neuropathy and a 24-2 VF with mean deviation better than -6 dB were prospectively studied and tested with a 10-2 test. Reliable: VF hemifields were classified as abnormal based on a cluster criterion, and abnormal 10-2 VFs were categorized based on the pattern of abnormal points: arcuatelike, widespread, or other. In addition, at each point of the 10-2 VF, the total deviation values were averaged across eyes and the number of abnormal points w...

To evaluate the accuracy and generalizability of a published model that derives estimates of retinal ganglion cell (RGC) counts and relates structural and functional changes due to glaucoma. Both the Harwerth et al. non-linear model (H-NLM) and the Hood and Kardon linear model (HK-LM) were applied to an independent dataset of frequency-domain optical coherence tomography and visual fields, consisting of 48 eyes of 48 healthy controls, 100 eyes of 77 glaucoma patients and suspects, and 18 eyes of 14 non-arteritic anterior ischemic optic neuropathy (ION) patients with severe vision loss. Using the coefficient of determination R(2), the models were compared while keeping constant the topographic maps, specifically a map by Garway-Heath et al. and a separate map by Harwerth et al., which relate sensitivity test stimuli locations to corresponding regions around the optic disc. Additionally, simulations were used to evaluate the assumptions of the H-NLM. Although the predictions of the HK...

The adult brain maintains the ability for reorganization or plasticity throughout life. Non-invasive techniques such as functional magnetic resonance imaging (f-MRI), Transcranial Magnetic Stimulation (TMS) and magnetoencephalography could be used to show recovery of function after stroke. Explanation of neuronal plastisity and intra-hemisferic reorganization with functional recovery of a case who has total extensive damage on the left hemisphere. case report: Twenty-five years old female patient was admitted to our hospital with a right-sided sequel hemiparesis and homonymous hemianopia. She had right-sided paresia after an inguinal hernia operation when she was one and a half years old. On neurological examination she was speaking fluently, and cooperated on complicated comments. Motor examination revealed right-sided spastic hemiparesis predominant on distal parts and right sided visual field defect. But she was continuing her activity of daily livings without help. Her detailed ...

Purpose-To report the incidence and clinical outcomes of non-cytomegalovirus (non-CMV) ocular opportunistic infections in patients with AIDS in the era of highly active antiretroviral therapy (HAART). Methods-Medical history, ophthalmologic examination, and laboratory tests were performed at enrollment and every 6 months subsequently. Once an ocular opportunistic infection was diagnosed, patients were seen every 3 months for outcomes. Results-At enrollment, 37 non-CMV ocular opportunistic infections were diagnosed: 16 patients, herpetic retinitis; 11 patients, toxoplasmic retinitis; and 10 patients, choroiditis. During

Aims: To determine waveforms of multifocal electroretinogram (mfERG) in patients with retinitis pigmentosa (RP) contributing signifi cantly to the overall retinal response by using principal components' analysis. Sett ings and Design: Prospective, non-randomized, single-visit, observational, case-control study from a single tertiary ophthalmic center. Materials and Methods: Patients with various forms of RP underwent mfERG testing for a period of one year. The fi rst-order kernel responses of RP cases were compared with concurrently recruited healthy controls. Statistical Analysis Used: Parametric data was analyzed using the unpaired t test for diff erences between the implicit time and amplitudes of cases and controls. Principal components' analysis was done for each implicit time and amplitude in cases with RP using the Varimax rotation method. Results: From March 2006 to March 2007, 24 cases with typical RP (56%, 47 eyes) were included in the fi nal analysis. Their mean age was 33.7 years (19-69+15.5 years). Comparison of latencies and amplitudes among RP cases with log MAR acuity < 0.18 and those > 0.18, revealed signifi cant diff erence in the implicit time (P1) in Ring 2 only (P=0.028). Two components (predominently from Ring 1 and 2) each contributing 66.8% and 88.8% of the total variance in the data for latencies and amplitudes respectively, were seen. Conclusions: The fi rst two rings of the mfERG contributed to the variance of waveforms in RP, irrespective of the visual acuity and poor visual fi eld results.

The values of Heidelberg Retinal Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) stereometric parameters depend on the reference plane (RP), the instability of which results in parameter variability. Identification of change depends on RP stability. This study was undertaken to evaluate the influence of various RPs on rim areas (RAs) in a longitudinal image series. METHODS. A longitudinal image series of 31 subjects with ocular hypertension who had reproducible visual field loss and 19 normal subjects was analyzed using five different RPs: the standard RP (HRT software version 3.1.2.0), two 320-m RPs (software ver. 3.1.2.0 and 1.7.0), a previously described experimental RP, and a new Moorfields RP. The Moorfields RP takes the standard RP at baseline and then is fixed relative to the reference ring for subsequent images. Linear regression of RA over time was performed, and the slope and residual SD (RSD) were calculated for each RP. Comparisons between RPs were made by paired t-tests. RESULTS. In eyes with progressing disease, application of the standard RP resulted in significantly greater variability (as measured by the RSD) compared with other RPs (mean 0.057 mm 2 vs. 0.035-0.038 mm 2 ). There was a trend toward faster RA change/time (mean, Ϫ0.0123 mm 2 /y) for the standard RP and slower (Ϫ0.0095 mm 2 /y) for the experimental RP. There was a trend for the Moorfields RP to result in the best signal-to-noise ratio (speed of RA change/variability): mean RA slope Ϫ0.0118 mm 2 /y and mean global RSD 0.037mm 2 . CONCLUSIONS. Compared to the standard RP, the Moorfields RP has significantly lower variability and probably provides a greater facility for discriminating RA change from measurement variability in a longitudinal HRT image series. (Invest

To validate a method for visual field (VF) progression analysis, called ANSWERS (Analysis with Non-Stationary Weibull Error Regression and Spatial Enhancement), which takes into account increasing measurement variability as glaucoma progresses and spatial correlation among test locations. METHODS. ANSWERS outputs both a global index of progression and a pointwise estimate of rate of change at each VF location. ANSWERS was compared with linear regression of mean deviation (MD) and permutation of pointwise linear regression (PoPLR). Visual field series of up to 2 years from the United Kingdom Glaucoma Treatment Study were used. This consists of 9104 Swedish Interactive Thresholding Algorithm Standard 24-2 VFs. ANSWERS and PoPLR rate of change were used to predict the VF at the next visit using subseries that were within 7, 13, 18, or 22 months from the baseline. The comparison was carried out on the statistical sensitivity, specificity, and accuracy of predicting future VF. RESULTS. Across all subseries, statistical sensitivity of ANSWERS in detecting VF deterioration was significantly better than the linear regression of MD and PoPLR, especially in short time series. Prediction accuracy of ANSWERS was better than PoPLR at all series lengths, and the improvement was particularly marked in shorter series. Seventy-five percent of VF series were better predicted by ANSWERS compared with PoPLR. The average prediction error of ANSWERS was 15% lower than that of PoPLR. ANSWERS is more sensitive to detect VF progression and predicts future VF loss better than linear regression of MD and PoPLR, especially over short observation periods. ( number, ISRCTN96423140.

To validate a method for visual field (VF) progression analysis, called ANSWERS (Analysis with Non-Stationary Weibull Error Regression and Spatial Enhancement), which takes into account increasing measurement variability as glaucoma progresses and spatial correlation among test locations. ANSWERS outputs both a global index of progression and a pointwise estimate of rate of change at each VF location. ANSWERS was compared with linear regression of mean deviation (MD) and permutation of pointwise linear regression (PoPLR). Visual field series of up to 2 years from the United Kingdom Glaucoma Treatment Study were used. This consists of 9104 Swedish Interactive Thresholding Algorithm Standard 24-2 VFs. ANSWERS and PoPLR rate of change were used to predict the VF at the next visit using subseries that were within 7, 13, 18, or 22 months from the baseline. The comparison was carried out on the statistical sensitivity, specificity, and accuracy of predicting future VF. Across all subserie...

The values of Heidelberg Retinal Tomograph (HRT; Heidelberg Engineering, Heidelberg, Germany) stereometric parameters depend on the reference plane (RP), the instability of which results in parameter variability. Identification of change depends on RP stability. This study was undertaken to evaluate the influence of various RPs on rim areas (RAs) in a longitudinal image series. METHODS. A longitudinal image series of 31 subjects with ocular hypertension who had reproducible visual field loss and 19 normal subjects was analyzed using five different RPs: the standard RP (HRT software version 3.1.2.0), two 320-m RPs (software ver. 3.1.2.0 and 1.7.0), a previously described experimental RP, and a new Moorfields RP. The Moorfields RP takes the standard RP at baseline and then is fixed relative to the reference ring for subsequent images. Linear regression of RA over time was performed, and the slope and residual SD (RSD) were calculated for each RP. Comparisons between RPs were made by paired t-tests. RESULTS. In eyes with progressing disease, application of the standard RP resulted in significantly greater variability (as measured by the RSD) compared with other RPs (mean 0.057 mm 2 vs. 0.035-0.038 mm 2 ). There was a trend toward faster RA change/time (mean, Ϫ0.0123 mm 2 /y) for the standard RP and slower (Ϫ0.0095 mm 2 /y) for the experimental RP. There was a trend for the Moorfields RP to result in the best signal-to-noise ratio (speed of RA change/variability): mean RA slope Ϫ0.0118 mm 2 /y and mean global RSD 0.037mm 2 . CONCLUSIONS. Compared to the standard RP, the Moorfields RP has significantly lower variability and probably provides a greater facility for discriminating RA change from measurement variability in a longitudinal HRT image series. (Invest

To investigate the influence of intersubject variation in ocular parameters on the mapping of retinal locations to the retinal nerve fiber layer and optic nerve head. One hundred retinal nerve fiber layer (RNFL) bundle photographs from 100 subjects were optimized digitally and single RNFL bundles manually traced back to the ONH where their entry point was noted. A 24-2 visual field (VF) grid pattern was superimposed onto the photographs in order to relate VF test points to intersecting RNFL bundles and their entry angles into the ONH. Axial length, spherical equivalent, the position of the ONH in relation to the fovea, size, orientation, tilt, and shape of the ONH were assessed. Multilevel linear models were generated for predicting the entry angle of RNFL bundles, based on ocular parameters. A total of 6388 RNFL bundles were traced. The influence of ocular parameters could be evaluated for 33 out of 52 VF locations. The position of the ONH in relation to the fovea was the most prominent predictor for variations in the mapping of retinal locations to the ONH, followed by disc area, axial length, spherical equivalent, disc shape, disc orientation, and disc tilt. CONCLUSIONS. Mapping of retinal locations to the optic nerve head varies between patients according to a given patient's ocular parameters. By considering these parameters, patienttailored, structure-function maps can be built and structural and functional measurements can be correlated more accurately. Individualized maps may assist clinicians detecting glaucoma and monitoring glaucomatous progression.

We suggest a low-vision reading aid based on user-customized text presented on a head-mounted display (HMD), and make an initial comparison to optical aids in participants with age-related macular degeneration (AMD). Biomimetic scrolling, a novel method of text presentation which mimics the natural movements of the eye while reading, was previously invented: while the user maintains a steady gaze, text is scrolled horizontally across the display in a series of pauses and steps that resemble the natural fixations and saccades of reading. This method, along with rapid serial visual presentation, continuous scrolling, and static text, was presented on smart glasses to 23 participants with macular disease. Reading speed and subjective preference of the smart glasses was compared to reading text printed on paper using the participants' habitual optical reading aid. Reading using smart glasses, the mean (±standard error) maximum reading speed was 122 ± 15 words per minute (wpm), compared to 74 ± 9 wpm using each participants' habitual optical magnifier. This is a statistically significant difference as confirmed by a paired-sample ttest, t(17) = -4.61, p < .001. In total, 70% of the participants preferred reading from the smart glasses compared to reading from paper, and 84% found doing so easier. Data from this small patient cohort with AMD have demonstrated enhanced reading performance using dynamic text presented on a spectacle type HMD-device. Loss of reading ability marks a major decline in quality

I wrote this book to help in my own day-to-day job as an IP Optometrist who manages Glaucoma in the community under the Scottish Community Glaucoma Scheme.  This scheme was developed to manage treated ocular hypertension and lower-risk glaucoma in a primary care setting

Purpose-to evaluate disease progression in a cohort of patients with clinical and genetic diagnosis of Stargardt disease. Subjects-56 selected patients with a clinical and molecular diagnosis of Stargardt disease, an early age of onset and a median follow-up length of two years. Methods-patients underwent routine examination including full-field electroretinography, microperimetry and optical coherence tomography. Main Outcome Measures-best corrected visual acuity, mean retinal sensitivity, fixation stability, preferred retinal locus, inner-outer segment (IS/OS) junction loss, atrophic lesion area. Results-56 patients with a mean age of disease onset of 15.3 years (range: 3 -28 years), a mean disease length of 12.1 years and a mean age at baseline of 27.4 years were analyzed. The median best corrected visual acuity was 20/200 in both eyes. Optical coherence tomography parameters (IS/OS alteration and retinal pigment epithelium lesion area) were obtained in 49 patients because signal quality was poor in the remaining 7 patients. Optical coherence tomography revealed a mean retinal pigment epithelium lesion area of 2.6 mm 2 , preserved foveal IS/OS in 4.1% of patients, loss of foveal IS/OS in 59.2%, and extensive loss of macular IS/OS in 36.7%. Microperimetric findings showed a reduced macular sensitivity (mean 10 dB) and an unstable fixation in half of the patient cohort. The longitudinal analysis showed a significant progressive reduction of best corrected visual acuity and macular sensitivity (at an estimated rate of 0.04 decimals and 1.19 dB per year, respectively) associated with a significant enlargement of retinal pigment epithelium lesion area (0.282 mm 2 per year). No significant changes in ophthalmoscopic findings and electroretinographic responses were detected.

Primary visual cortex (PVC) contains a retinotopic map in which the central visual field (CVF) is highly magnified compared to the peripheral field. Several studies have used functional magnetic resonance imaging (fMRI) in patients with macular degeneration to assess the reorganization of visual processing in relationship with the development of extrafoveal preferred retinal locus (PRL). We evaluated the functional response in PVC and its correlation with retinal parameters in patients with Stargardt disease due to ABCA4 mutations (STGD1). Twenty-four STGD1 patients underwent best-corrected visual acuity, full-field standard electroretinogram (ERG), optical coherence tomography, and microperimetry. Furthermore, patients underwent fMRI to assess cerebral activation during visual stimulation by a flickering checkerboard in four PVC subdivisions, corresponding to 0° to 5° (V1), 5° to 10° (V2), 10° to 15° (V3), and 15° to 40° (V4) of CVF. Higher ERG responses were significantly (P &lt; ...

Purpose-to evaluate disease progression in a cohort of patients with clinical and genetic diagnosis of Stargardt disease. Subjects-56 selected patients with a clinical and molecular diagnosis of Stargardt disease, an early age of onset and a median follow-up length of two years. Methods-patients underwent routine examination including full-field electroretinography, microperimetry and optical coherence tomography. Main Outcome Measures-best corrected visual acuity, mean retinal sensitivity, fixation stability, preferred retinal locus, inner-outer segment (IS/OS) junction loss, atrophic lesion area. Results-56 patients with a mean age of disease onset of 15.3 years (range: 3 -28 years), a mean disease length of 12.1 years and a mean age at baseline of 27.4 years were analyzed. The median best corrected visual acuity was 20/200 in both eyes. Optical coherence tomography parameters (IS/OS alteration and retinal pigment epithelium lesion area) were obtained in 49 patients because signal quality was poor in the remaining 7 patients. Optical coherence tomography revealed a mean retinal pigment epithelium lesion area of 2.6 mm 2 , preserved foveal IS/OS in 4.1% of patients, loss of foveal IS/OS in 59.2%, and extensive loss of macular IS/OS in 36.7%. Microperimetric findings showed a reduced macular sensitivity (mean 10 dB) and an unstable fixation in half of the patient cohort. The longitudinal analysis showed a significant progressive reduction of best corrected visual acuity and macular sensitivity (at an estimated rate of 0.04 decimals and 1.19 dB per year, respectively) associated with a significant enlargement of retinal pigment epithelium lesion area (0.282 mm 2 per year). No significant changes in ophthalmoscopic findings and electroretinographic responses were detected.

Yet the synaptic processes that transmit visual information through cortex remain unresolved. This gap exists because most earlier studies have employed techniques unable to reveal intracellular events or have used in vitro preparations where natural means of stimulation are impossible. To study directly the synaptic patterns of signal transfer through the cortical circuit, we combined the techniques of whole-cell recording and intracellular labelling in vivo (Pei et al. 1991; Ferster & Jagadeesh, 1992) with traditional types of visual stimulation. Taken together, studies of the early visual pathway suggest that sensory information is strongly gated as it is relayed from layer 4 to layer 2+3 -from the first to the second cortical station. Layer 4 is defined as the first stage of cortical integration because it is the main recipient of thalamic input (

The work of Mircea Steriade demonstrated that the neocortex could synchronize large regions of the thalamus within 10-100 milliseconds (for review see Timofeev, 2003, Steriade, 2005). Unlike the synchrony generated by the cortex, the retinal afferents synchronize a restricted group of neighboring thalamic neurons with <1-millisecond precision . Here, we use a large sample (n= 372) of simultaneous recordings from neighboring neurons in the Lateral Geniculate Nucleus (LGN) to illustrate the high specificity of the synchrony generated by retinal afferents and its dependency on sensory stimulation. First, we demonstrate that cells sharing a retinal afferent show a balanced receptive field diversity: while slight receptive field mismatches are common, the largest mismatches in a specific property (e.g. receptive field size) are restricted to cells that are precisely matched in other properties (e.g. receptive field overlap). Second, we show that these receptive field mismatches are functionally important and can lead to a 5-fold variation in the percentage of synchronous spikes driven by the shared retinal afferent under different stimulus conditions. Based on these and other findings, we speculate that the precise synchronous firing of cells sharing a retinal afferent could serve to amplify local stimuli that may be too brief and small to generate a large number of thalamic spikes.

Against a hierarchical model, previous studies by Mal-Spain peli (1983) showed that the pharmacological blockade 3 Department of Psychology of a main layer (layer A) in lateral geniculate nucleus University of Connecticut (LGN) inactivated layer 4 simple cells but not layer 2ϩ3 Storrs, Connecticut 06269 complex cells. The activity of layer 2ϩ3 cells was thought to be maintained by inputs that originate in other thalamic structures either through a direct projection Summary to area 17 or indirectly through feed back connections (Malpeli, 1983; Malpeli et al., 1986; Mignard and Malpeli, In primary visual cortex, neurons are classified into 1991). Malpeli's results, and the discovery that some simple cells and complex cells based on their response complex cells receive direct geniculate input (Hoffmann properties. Although the role of these two cell types and Stone, 1971; Singer et al., 1975; Bullier and Henry, in vision is still unknown, an attractive hypothesis is 1979; Ferster and Lindstrom, 1983; Tanaka, 1983; Martin that simple cells are necessary to construct complex and Whitteridge, 1984), motivated compelling alternareceptive fields. This hierarchical model puts forward tives to the hierarchical model. two main predictions. First, simple cells should con-"Parallel models" proposed that simple cells and comnect monosynaptically to complex cells. Second, complex cells were both constructed from direct geniculate plex cells should become silent when simple cells are inputs. Based on the fact that simple cells, but not cominactivated. We have recently provided evidence for plex cells, show linear spatial summation (Skottun et al., the first prediction, and here we do the same for the 1991), parallel models suggested that simple cells were second. In summary, our results suggest that the recreated from the convergence of linear X geniculate ceptive fields of most layer 2ϩ3 complex cells are inputs and complex cells from the convergence of nongenerated by a mechanism that requires simple cell linear Y geniculate inputs (Hoffmann and Stone, 1971; inputs.

Highlights d Directionally selective (DS) neurons in the rabbit LGN project to the visual cortex d We examine the synaptic impact of single LGN DS axons within the cortex d LGN DS neurons provide a fast and powerful synaptic drive to layers 4 and 6 d LGN DS neurons strongly activate cortical fast-spike interneurons in these layers Authors

To investigate the relationship between reaction time (RT), stimulus intensity and visual field eccentricity. We generated frequency of seeing (FOS) curves and measured RTs by testing 10 perimetrically experienced normal subjects with a Humphrey perimeter controlled by a custom program. Subjects were tested from 10°to 50°eccentricity along the nasal horizontal meridian in 10°i ncrements. A range of 20 dB, centered on threshold, was tested in 1 dB steps along with 60 and 0 dB intensities as catch trials. Twenty repetitions for each intensity at each location were used. Linear regression showed a significant increase in suprathreshold RT (to the 0 dB stimulus) with increasing eccentricity. The RT at the calculated FOS 50% threshold was prolonged by about 200 ms compared with the RT using the 0 dB target at the equivalent eccentricities. Also, when the difference between the RT at 0 dB stimulus and the RT at threshold was regressed against visual field eccentricity there was a significant decrease with eccentricity. When the RT pi (RT prolongation from threshold relative to the 0 dB stimulus) was plotted as a function of decreasing stimulus attenuation, the results fit the function RT pi ¼ a þ bi 3 (i ¼ stimulus intensity) with r 2 > 0:94 at all eccentricities. However, the slope of the function flattened with increasing eccentricity. Using conventional automated perimetry stimuli in perimetrically experienced young subjects, suprathreshold RT increases but threshold RT prolongation decreases with increasing visual field eccentricity. RT fits a power function with decreasing stimulus attenuation but the slope flattens with eccentricity. This relationship found along the nasal horizontal meridian may allow use of RT to cross-check threshold results or to define response windows for reliability indices of conventional automated perimetry. Published by Elsevier Science Ltd.

To investigate the relationship between reaction time (RT), stimulus intensity and visual field eccentricity. We generated frequency of seeing (FOS) curves and measured RTs by testing 10 perimetrically experienced normal subjects with a Humphrey perimeter controlled by a custom program. Subjects were tested from 10°to 50°eccentricity along the nasal horizontal meridian in 10°i ncrements. A range of 20 dB, centered on threshold, was tested in 1 dB steps along with 60 and 0 dB intensities as catch trials. Twenty repetitions for each intensity at each location were used. Linear regression showed a significant increase in suprathreshold RT (to the 0 dB stimulus) with increasing eccentricity. The RT at the calculated FOS 50% threshold was prolonged by about 200 ms compared with the RT using the 0 dB target at the equivalent eccentricities. Also, when the difference between the RT at 0 dB stimulus and the RT at threshold was regressed against visual field eccentricity there was a significant decrease with eccentricity. When the RT pi (RT prolongation from threshold relative to the 0 dB stimulus) was plotted as a function of decreasing stimulus attenuation, the results fit the function RT pi ¼ a þ bi 3 (i ¼ stimulus intensity) with r 2 > 0:94 at all eccentricities. However, the slope of the function flattened with increasing eccentricity. Using conventional automated perimetry stimuli in perimetrically experienced young subjects, suprathreshold RT increases but threshold RT prolongation decreases with increasing visual field eccentricity. RT fits a power function with decreasing stimulus attenuation but the slope flattens with eccentricity. This relationship found along the nasal horizontal meridian may allow use of RT to cross-check threshold results or to define response windows for reliability indices of conventional automated perimetry. Published by Elsevier Science Ltd.

Objective: To measure the short-and long-term variability of automated perimetry in patients with optic neuritis and normal subjects. Design: Prospective case-control design of patients with recovered optic neuritis with intraday and interday repetitions to obtain robust variability measurements. Entry criteria included a corrected pattern SD that was worse than the normal 5% probability level and a mean deviation worse than -3 dB but better than -20 dB. Five Humphrey 30-2 full threshold tests were administered during a 7-hour period (1 test every 2 hours) on the same day and at the same periods on 5 separate days. Subjects: Seventeen patients with recovered optic neuritis and 10 healthy subjects of similar age. Main Outcome Measures: Short-term variability and long-term variability for global visual field data. Results: Patients with optic neuritis demonstrated variations in visual field sensitivity that were outside the entire range of variability for normal controls. These variations occurred for multiple tests performed on the same

Italian children (n ¼ 125) were classified into dyslexics, poor readers and ordinary readers. The dyslexics were further classified into the Boder and Bakker subtypes. The children were tested with the form-resolving field (FRF), which measures central and peripheral visual recognition. Dyslexics show higher correct identification of letters in the periphery, supporting the notion of a different distribution of lateral masking. A numerical characterization of individual FRFs--C2R--reliably distinguishes between dyslexics and ordinary readers. The wider distribution of recognition, similar across the various subtypes of dyslexia, suggests a general characteristic of visual perception, and possibly a different visual-attentional mode.

When the eye saccades to eccentric word targets, it tends to land in a position which can be described as the center of gravity of the configuration. By manipulating the relative intensity of the word-initial and -ending letters, it was shown that the 'global effect' of luminance distribution within words is strongly attenuated when the word-initial letters are informative and orthographically irregular. Results show that the orthographic structure of the word-initial letters exerts an influence on the saccadic computation that may cancel the luminance distribution effect.

When the eye saccades to eccentric word targets, it tends to land in a position which can be described as the center of gravity of the configuration. By manipulating the relative intensity of the word-initial and -ending letters, it was shown that the 'global effect' of luminance distribution within words is strongly attenuated when the word-initial letters are informative and orthographically irregular. Results show that the orthographic structure of the word-initial letters exerts an influence on the saccadic computation that may cancel the luminance distribution effect.

Photobiological eyewear, defined as spectacle lenses engineered to selectively attenuate specific wavelength bands based on published photoreceptor action spectra, represents an emerging category in optometric practice. Unlike generic blue-light-filtering (BLF) lenses that provide broad-spectrum attenuation across the 400-450 nm range, photobiological lenses target discrete wavelength regions implicated in specific clinical conditions: the melanopsin-ipRGC activation band (460-490 nm) for migraine photophobia, the full melanopsin sensitivity envelope (460-560 nm) for circadian disruption and sleep disorders, and the high-energy visible (HEV) band (400-450 nm) for daytime photic comfort. This paper presents a clinical decision framework to assist optometrists in selecting condition-appropriate photobiological lenses based on patient presentation, symptom profile, and time-of-day considerations. We review the photobiological basis for each lens category, summarise the relevant clinical evidence, present three representative clinical scenarios, propose a structured patient assessment protocol, and discuss integration with existing prescription workflows. The framework addresses a gap in current optometric practice where a single generic BLF coating is commonly prescribed regardless of the patient's specific photobiological condition, contrary to the established principle of condition-specific optical management.

The macula is essential for visual functioning and is known to be affected even in early glaucoma. However, little is currently understood about the prevalence and nature of central vision loss in early glaucoma. To determine the prevalence and characteristics of visual field (VF) defects in the central 10° in glaucoma suspects and patients with mild glaucoma using a prospective design. This prospective observational cohort study was conducted at an outpatient glaucoma specialty clinic. One hundred eyes from 74 patients with glaucomatous optic neuropathy and a 24-2 VF with mean deviation better than -6 dB were prospectively studied and tested with a 10-2 test. Reliable: VF hemifields were classified as abnormal based on a cluster criterion, and abnormal 10-2 VFs were categorized based on the pattern of abnormal points: arcuatelike, widespread, or other. In addition, at each point of the 10-2 VF, the total deviation values were averaged across eyes and the number of abnormal points w...

To evaluate the accuracy and generalizability of a published model that derives estimates of retinal ganglion cell (RGC) counts and relates structural and functional changes due to glaucoma. Both the Harwerth et al. non-linear model (H-NLM) and the Hood and Kardon linear model (HK-LM) were applied to an independent dataset of frequency-domain optical coherence tomography and visual fields, consisting of 48 eyes of 48 healthy controls, 100 eyes of 77 glaucoma patients and suspects, and 18 eyes of 14 non-arteritic anterior ischemic optic neuropathy (ION) patients with severe vision loss. Using the coefficient of determination R(2), the models were compared while keeping constant the topographic maps, specifically a map by Garway-Heath et al. and a separate map by Harwerth et al., which relate sensitivity test stimuli locations to corresponding regions around the optic disc. Additionally, simulations were used to evaluate the assumptions of the H-NLM. Although the predictions of the HK...

PURPOSE. We measured macular inner retinal layer thicknesses using frequency-domain optical coherence tomography (fd-OCT) and correlated these measures with visual field (VF) in eyes with temporal hemianopia from chiasmal compression and band atrophy (BA) of the optic nerve. METHODS. Macular fd-OCT scans and VFs were obtained from 33 eyes of 33 patients with temporal hemianopia and 36 control eyes. The macular retinal nerve fiber layer (mRNFL), combined retinal ganglion cell and inner plexiform layers (RGCLþ), and the inner nuclear layer (INL) were segmented. Measurements were averaged for each macula quadrant. Scans were assessed qualitatively for microcysts in the INL. The VF was estimated from the central 16 test points. The two groups were compared. Correlations between VF and OCT measurements were assessed. RESULTS. The mRNFL, RGCLþ, and total retinal (TR) macular thickness measurements were significantly smaller in BA eyes than controls. In the nasal quadrants, INL measurements were significantly greater in BA eyes than controls. The mRNFL and RGCLþ measurements had greater discrimination ability than TR measurements in the temporal quadrants. A significant correlation was found between most OCT parameters and their corresponding VF parameters. The strongest association was observed between RNFL and RGCLþ thickness, and VF loss in the corresponding area. The INL microcysts were found in seven eyes with BA, but not in controls. CONCLUSIONS. Band atrophy leads to mRNFL and RGCLþ thinning, and INL thickening, and mRNFL and RGCLþ measurements are correlated strongly with VF loss. Segmented macular thickness measurements may be useful for quantifying neuronal loss in chiasmal compression.

To describe a macrodeletion spanning entire RCC1-like doman in the RPGR gene in one Japanese family with X-linked retinitis pigmentosa (XLRP). Clinical ophthalmologic examinations were performed and genomic DNA was extracted from blood samples. Genomic DNA was analyzed by Southern blot and PCR amplification with specific primers. Patients had severe symptoms with early onset and rapid deterioration. PCR amplification and Southern blot analysis revealed the absence of the 5&#39; half of the RPGR gene. The deletion was confirmed and characterized by designing flanking PCR primers: the deletion start point was located 80 bp upstream of the translation start site in exon 1, the end point was 42 bp downstream of exon 11. This 30 kb deletion contains the exons coding for the RCC1-like domain of RPGR. It is the first report of a macrodeletion that spans the entire RCC1-like domain of RPGR in X-linked retinitis pigmentosa patients, and suggests that loss of function of this domain disrupts ...

Fifty-seven eyes of 49 patients with senile retinoschisis were treated by argon laser photocoagulation and followed up for 3 to 6 years. In most of the treated eyes the retinoschisis either completely or partially collapsed and in none did the retinoschisis or loss of visual field progress further. No long-term complications due to the treatment were noted. In none of the treated eyes did retinal detachment develop. In view of this the indications at present for argon laser treatment in retinoschisis may be extended to include any case in which the retinoschisis progresses beyond the equator and visual field loss continues. This may prevent further visual field damage and other rare complications of slowly progressive retinoschisis and facilitate the many years' follow-up of elderly patients with retinoschisis who develop cataracts. Senile, or degenerative, retinoschisis which is noted in adult life, is believed to be the end result of cystoid peripheral retinal degeneration. 1-3 The disease was described as involving splitting of the retina through the anterior plexiform layer between the nuclei of the visual cells and the bipolars. I 2I4 S In a comprehensive study based on clinical and pathological observations Foss6 and Straatsma and Foos7 differentiated between 'typical' or 'flat' and 'reticular' or 'bulbous' retinoschisis. The prevalence of the disease was report to be 0-7% of adult eyes in the typical retinoschisis and 0 95% of adult eyes in the reticular retinoschisis.7 The process starts at the extreme periphery of the retina and spreads towards the posterior pole.89 Sometimes this process is multifocal, and there is no communication between the retinoschisis bullae.'°T here is still a significant difference of opinion on the rate of progression and symptomatology of the disease, the importance of demarcation line, and the risk of retinal detachment.'0 In most cases the disease remains stationary indefinitely, while in others it progresses very slowly. However, although rare, the disease may lead to a considerable loss of vision either by involving the macula or as a result of breaks in the outer or both retinal layers which lead to true retinal detachment.' 89 11 12 The expected rate of retinal detachment was found to be very low by Byer,' while other authors considered the risk to be much higher. 11-11

Rare ischaemic complications have been reported after oral nifedipine, but none of these affected the retinal circulation. We report on a patient who developed repeated transient unilateral retinal ischaemia after administration of nifedipine. Seven years after suffering an anteroseptal myocardial infarction a 67 year old man presented with angina of one year's duration that did not respond unit ISAAC LIPSHITZ, MD, senior registrar, neuro-ophthalmological unit GERSHON PERRY, MD, registrar, department of internal medicine C JOSEPH ROSENFELD, MD, professor and chief, department of

Orbital lymphoma represents a small fraction of all systemic lymphomas that has been accounted for approximately in 1-2% of non-Hodgkin lymphomas (NHL). Some diagnostic delays might be occurred due to the fact that there are non-specific clinical signs. Furthermore, an orbital CT scan can determine the location of the orbital mass and assist in ophthalmological surgery as well as to obtain an optimal sample for an accurate diagnosis. CT scan was performed and revealed the pattern of orbital lymphoma in order to pursue the proper diagnosis. In accordance to the imaging result, immunohistochemical studies were performed from biopsy specimens of all three patients. It showed that there were a non-Hodgkin's lymphomas originating in the orbit, lids, and oculi adnexa.

Stereotactic radiosurgery (SRS) may be an alternative to anterior temporal lobectomy (ATL) for mesial temporal lobe epilepsy (MTLE). Visual field defects (VFD) occur in 9-100% of patients following open surgery for MTLE. Postoperative VFD after minimally invasive versus open surgery may differ. Methods: This prospective trial randomized patients with unilateral hippocampal sclerosis and concordant video-EEG findings to SRS versus ATL. Humphries perimetry was obtained at 24 m after surgery. VFD ratios (VFDR = proportion of missing homonymous hemifield with 0 = no VFD, 0.5 = complete superior quadrantanopsia) quantified VFD. Regressions of VFDR were evaluated against treatment arm and covariates. MRI evaluated effects of volume changes on VFDR. The relationships of VFDR with seizure remission and driving status 3 years after surgery were evaluated. Results: No patients reported visual changes or had abnormal bedside examinations, but 49 of 54 (91%) of patients experienced VFD on formal perimetry. Neither incidence nor severity of VFDR differed significantly by treatment arm. VFDR severity was not associated with seizure remission or driving status. Conclusion: The nature of VFD was consistent with lesions of the optic radiations. Effective surgery (defined by seizure remission) of the mesial temporal lobe results in about a 90% incidence of typical VFD regardless of method.

To investigate whether implantation of a glaucoma shunt device leads to inappropriate accumulation of plasma derived proteins in the aqueous humor. Aqueous humor samples were collected from 11 patients (study group) with a glaucoma shunt device undergoing either cataract surgery or a corneal transplant and 11 patients (control) with senile cataract undergoing routine cataract extraction. Of the study group, 9 had an Ahmed valve implant and 2 eyes had a Baerveldt implant. Tryptic digests of the mixture of proteins in aqueous humor (AH) were analyzed using Liquid Chromatography/Mass Spectrometry (LC-MS/MS). Proteins were identified with high confidence using stringent criteria and compared quantitatively using a label-free platform (IdentiQuantXL™). We identified 135 proteins in the albumin-depleted fraction in both the study and control group AH. Using stringent criteria, 13 proteins were detected at a significantly higher level compared to controls. These proteins are known to play ...

Introduction: There are several limitations of the Amsler chart as a screening tool due to its low sensitivity and high false-negative results. The Berkeley central visual field test (BCFT), which is a simple power-point presentation of a 50-point scoring system for the central 10-degree of the visual field, was devised as an alternative to the Amsler chart.Objectives: To compare the efficacy of measuring the central visual field using the Berkeley central field test (BCFT) and the Amsler grid test.Materials and methods: In a comparative and validity study, 30 subjects with maculopathy and 35 controls were recruited. The maculopathy subjects with the best corrected visual acuity of 20/200 or better and 2.5M for distant and near vision respectively, were included. All the subjects under went a complete eye examination where visual assessment was done using the distant and near vision Log MAR Chart. The subjects were assessed with the Amsler chart-II at a distance of 30 cm. The BCFT w...

The exquisite ability of primates to grasp and manipulate objects relies on the transformation of visual information into motor commands. To this end, the visual system extracts object affordances that can be used to program and execute the appropriate grip. The macaque anterior intraparietal (AIP) area has been implicated in the extraction of affordances for the purpose of grasping. Neurons in the AIP area respond during visually guided grasping and to the visual presentation of objects. A subset of AIP neurons is also activated by two-dimensional images of objects and even by outline contours defining the object shape, but it is unknown how AIP neurons actually represent object shape. In this study, we used a stimulus reduction approach to determine the minimum effective shape feature evoking AIP responses. AIP neurons responding to outline shapes also responded selectively to very small fragment stimuli measuring only 1-2°. This fragment selectivity could not be explained by diff...