BACKGROUND AND OBJECTIVE

A parachiasmal lesion is defined as a mass or growth arising from structures around or near the chiasm. Ophthalmologic signs and symptoms may be observed in such condition, such as blurring of vision, visual field defects, and binocular double vision. The primary objective of this study was to describe the presenting ophthalmologic signs and symptoms of parachiasmal lesions among patients consulting at a single institution in the Philippines.

This was a single-center, retrospective, cohort study. Medical records of patients with parachiasmal lesions seen in the Neuro-Ophthalmology clinic of a tertiary Philippine hospital from January 2014 to December 2019 were reviewed. Clinical profile, neuro-ophthalmologic presentation, diagnosis, management, and visual outcomes were summarized by descriptive statistics.

One hundred thirty-three (133) patient records satisfied the study criteria. Most common presenting symptoms were blurring of vision. headache, and loss of vision. Visual acuity at initial visit ranged from 20/20 to no light perception. A relative afferent pupillary defect was present in half of the study population. Almost half presented with normal-looking discs or disc pallor. Bitemporal hemianopia is the most common visual field defect pattern seen in both confrontation and automated visual field testing. Histopathology was significantly associated with visual outcome.

Parachiasmal lesion should be suspected in patients who complain of unilateral blurring of vision, and those who present with normal or pale optic discs. Pituitary adenoma is the most common radiologic and histopathologic diagnosis. Visual outcome after intervention has improved or remained stable in two-thirds of patients; visual recovery is multi-factorial, which is influenced by duration, surgery, and histopathology.

Background and Objective: A parachiasmal lesion is defined as a mass or growth arising from structures around or near the chiasm. Ophthalmologic signs and symptoms may be observed in such condition, such as blurring of vision, visual field defects, and binocular double vision. The primary objective of this study was to describe the presenting ophthalmologic signs and symptoms of parachiasmal lesions among patients consulting at a single institution in the Philippines. Methods: This was a single-center, retrospective, cohort study. Medical records of patients with parachiasmal lesions seen in the Neuro-Ophthalmology clinic of a tertiary Philippine hospital from January 2014 to December 2019 were reviewed. Clinical profile, neuro-ophthalmologic presentation, diagnosis, management, and visual outcomes were summarized by descriptive statistics. Results: One hundred thirty-three (133) patient records satisfied the study criteria. Most common presenting symptoms were blurring of vision. headache, and loss of vision. Visual acuity at initial visit ranged from 20/20 to no light perception. A relative afferent pupillary defect was present in half of the study population. Almost half presented with normal-looking discs or disc pallor. Bitemporal hemianopia is the most common visual field defect pattern seen in both confrontation and automated visual field testing. Histopathology was significantly associated with visual outcome. Conclusion Parachiasmal lesion should be suspected in patients who complain of unilateral blurring of vision, and those who present with normal or pale optic discs. Pituitary adenoma is the most common radiologic and histopathologic diagnosis. Visual outcome after intervention has improved or remained stable in two-thirds of patients; visual recovery is multi-factorial, which is influenced by duration, surgery, and histopathology.
visual fields ; retrospective studies ; Philippines ; pituitary neoplasm ; visual acuity

BACKGROUND

Pediatric cataract is one of the most common preventable cause of childhood blindness worldwide. Early and timely intervention of pediatric cataract is important to maximize the visual outcomes and start prompt visual rehabilitation.

This study aimed to determine the average time from the day of initial consult at the outpatient clinic to the day of the cataract surgery and compare the effects of delayed surgery on visual outcomes of patients.

This is a retrospective chart review of medical records from January 2015 to June 2022. The dates of the different steps in the process up to the day of intervention were noted and the average interval duration and the total waiting time were determined. Patients operated on within 2 weeks from initial consult was defined as no delay while those operated >2 weeks had delayed surgery. Pre-operative and post-operative best corrected log MAR visual acuity were compared within each group to determine if delay in surgical intervention has a significant effect on the visual outcomes of patients.

Median age at initial consult was 4.9 years while median age at surgery was 5.2 years. Ninety-nine (99) patients had developmental cataract and 123 patients had bilateral cataract. Leukocoria was the most common chief complaint (63.45%). Pre-operatively, 94 patients had strabismus, 49 had eye preference, 48 had nystagmus, and 43 had amblyopia in the diagnosis. There was significantly faster admission to cataract surgery during the pandemic compared to pre-pandemic period but there was no difference in the total waiting time. Patients with congenital cataract had the least total waiting time followed by developmental, and rubella cataract. There is no significant difference in visual outcomes between patients operated without delay and with delay.

There is delayed age at diagnosis and surgery of pediatric cataract patients in the Philippine General Hospital. Early surgery did not reflect better visual outcomes compared to delayed surgery probably due to delay in consultation of patients.

Even though retinal images of objects change their locations following each eye movement, we perceive a stable and continuous world. One possible mechanism by which the brain achieves such visual stability is to construct a craniotopic coordinate by integrating retinal and extraretinal information. There have been several proposals on how this may be done, including eye-position modulation (gain fields) of retinotopic receptive fields (RFs) and craniotopic RFs. In the present study, we investigated coordinate systems used by RFs in the lateral intraparietal (LIP) cortex and frontal eye fields (FEF) and compared the two areas. We mapped the two-dimensional RFs of neurons in detail under two eye fixations and analyzed how the RF of a given neuron changes with eye position to determine its coordinate representation. The same recording and analysis procedures were applied to the two brain areas. We found that, in both areas, RFs were distributed from retinotopic to craniotopic representations. There was no significant difference between the distributions in the LIP and FEF. Only a small fraction of neurons was fully craniotopic, whereas most neurons were between the retinotopic and craniotopic representations. The distributions were strongly biased toward the retinotopic side but with significant craniotopic shifts. These results suggest that there is only weak evidence for craniotopic RFs in the LIP and FEF, and that transformation from retinotopic to craniotopic coordinates in these areas must rely on other factors such as gain fields.
Animals ; Macaca ; Visual Fields ; Frontal Lobe/physiology* ; Eye Movements ; Brain

During natural viewing, we often recognize multiple objects, detect their motion, and select one object as the target to track. It remains to be determined how such behavior is guided by the integration of visual form and motion perception. To address this, we studied how monkeys made a choice to track moving targets with different forms by smooth pursuit eye movements in a two-target task. We found that pursuit responses were biased toward the motion direction of a target with a hole. By computing the relative weighting, we found that the target with a hole exhibited a larger weight for vector computation. The global hole feature dominated other form properties. This dominance failed to account for changes in pursuit responses to a target with different forms moving singly. These findings suggest that the integration of visual form and motion perception can reshape the competition in sensorimotor networks to guide behavioral selection.
Animals ; Pursuit, Smooth ; Macaca mulatta ; Motion Perception/physiology* ; Photic Stimulation

Integrating multisensory inputs to generate accurate perception and guide behavior is among the most critical functions of the brain. Subcortical regions such as the amygdala are involved in sensory processing including vision and audition, yet their roles in multisensory integration remain unclear. In this study, we systematically investigated the function of neurons in the amygdala and adjacent regions in integrating audiovisual sensory inputs using a semi-chronic multi-electrode array and multiple combinations of audiovisual stimuli. From a sample of 332 neurons, we showed the diverse response patterns to audiovisual stimuli and the neural characteristics of bimodal over unimodal modulation, which could be classified into four types with differentiated regional origins. Using the hierarchical clustering method, neurons were further clustered into five groups and associated with different integrating functions and sub-regions. Finally, regions distinguishing congruent and incongruent bimodal sensory inputs were identified. Overall, visual processing dominates audiovisual integration in the amygdala and adjacent regions. Our findings shed new light on the neural mechanisms of multisensory integration in the primate brain.
Animals ; Macaca ; Acoustic Stimulation ; Auditory Perception/physiology* ; Visual Perception/physiology* ; Amygdala/physiology* ; Photic Stimulation

BACKGROUND: Patients with mass-forming pancreatitis (MFP) or pancreatic ductal adenocarcinoma (PDAC) presented similar clinical symptoms, but required different treatment approaches and had different survival outcomes. This meta-analysis aimed to compare the diagnostic performance of contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT) in differentiating MFP from PDAC. METHODS: A literature search was performed in the PubMed, EMBASE (Ovid), Cochrane Library (CENTRAL), China National Knowledge Infrastructure (CNKI), Weipu (VIP), and WanFang databases to identify original studies published from inception to August 20, 2021. Studies reporting the diagnostic performances of CEUS and CECT for differentiating MFP from PDAC were included. The meta-analysis was performed with Stata 15.0 software. The outcomes included the pooled sensitivity, specificity, positive likelihood ratio (+LR), negative likelihood ratio (-LR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves of CEUS and CECT. Meta-regression was conducted to investigate heterogeneity. Bayesian network meta-analysis was conducted to indirectly compare the overall diagnostic performance. RESULTS: Twenty-six studies with 2115 pancreatic masses were included. The pooled sensitivity and specificity of CEUS for MFP were 82% (95% confidence interval [CI], 73%-88%; I2  = 0.00%) and 95% (95% CI, 90%-97%; I2  = 63.44%), respectively; the overall +LR, -LR, and DOR values were 15.12 (95% CI, 7.61-30.01), 0.19 (95% CI, 0.13-0.29), and 78.91 (95% CI, 30.94-201.27), respectively; and the area under the SROC curve (AUC) was 0.90 (95% CI, 0.87-92). However, the overall sensitivity and specificity of CECT were 81% (95% CI, 75-85%; I2  = 66.37%) and 94% (95% CI, 90-96%; I2  = 74.87%); the overall +LR, -LR, and DOR values were 12.91 (95% CI, 7.86-21.20), 0.21 (95% CI, 0.16-0.27), and 62.53 (95% CI, 34.45-113.51), respectively; and, the SROC AUC was 0.92 (95% CI, 0.90-0.94). The overall diagnostic accuracy of CEUS was comparable to that of CECT for the differential diagnosis of MFP and PDAC (relative DOR 1.26, 95% CI [0.42-3.83], P  > 0.05). CONCLUSIONS CEUS and CECT have comparable diagnostic performance for differentiating MFP from PDAC, and should be considered as mutually complementary diagnostic tools for suspected focal pancreatic lesions.
Humans ; Contrast Media ; Bayes Theorem ; Tomography, X-Ray Computed/methods* ; Pancreatic Neoplasms/diagnostic imaging* ; Carcinoma, Pancreatic Ductal/diagnostic imaging* ; Sensitivity and Specificity ; Pancreatitis/diagnostic imaging* ; Ultrasonography/methods*

With inherent sparse spike-based coding and asynchronous event-driven computation, spiking neural network (SNN) is naturally suitable for processing event stream data of event cameras. In order to improve the feature extraction and classification performance of bio-inspired hierarchical SNNs, in this paper an event camera object recognition system based on biological synaptic plasticity is proposed. In our system input event streams were firstly segmented adaptively using spiking neuron potential to improve computational efficiency of the system. Multi-layer feature learning and classification are implemented by our bio-inspired hierarchical SNN with synaptic plasticity. After Gabor filter-based event-driven convolution layer which extracted primary visual features of event streams, we used a feature learning layer with unsupervised spiking timing dependent plasticity (STDP) rule to help the network extract frequent salient features, and a feature learning layer with reward-modulated STDP rule to help the network learn diagnostic features. The classification accuracies of the network proposed in this paper on the four benchmark event stream datasets were better than the existing bio-inspired hierarchical SNNs. Moreover, our method showed good classification ability for short event stream input data, and was robust to input event stream noise. The results show that our method can improve the feature extraction and classification performance of this kind of SNNs for event camera object recognition.
Visual Perception ; Learning ; Action Potentials ; Neural Networks, Computer ; Neuronal Plasticity

Three different preclinical evaluation methods of MTF through-frequency response, MTF through-focus-response and expected visual acuity were used to compare and analyze the imaging differences of IOLs with four different optical designs. The research work could be used in the simultaneous vision IOLs in the optical design stage and verify the optical quality of the IOLs, the results can predict the visual representation of the patients better. The evaluation results can provide reference for IOL manufacturers and users in product design, development, validation and application selection.
Humans ; Prosthesis Design ; Lenses, Intraocular ; Vision, Ocular ; Visual Acuity

Accurate self-motion perception, which is critical for organisms to survive, is a process involving multiple sensory cues. The two most powerful cues are visual (optic flow) and vestibular (inertial motion). Psychophysical studies have indicated that humans and nonhuman primates integrate the two cues to improve the estimation of self-motion direction, often in a statistically Bayesian-optimal way. In the last decade, single-unit recordings in awake, behaving animals have provided valuable neurophysiological data with a high spatial and temporal resolution, giving insight into possible neural mechanisms underlying multisensory self-motion perception. Here, we review these findings, along with new evidence from the most recent studies focusing on the temporal dynamics of signals in different modalities. We show that, in light of new data, conventional thoughts about the cortical mechanisms underlying visuo-vestibular integration for linear self-motion are challenged. We propose that different temporal component signals may mediate different functions, a possibility that requires future studies.
Animals ; Humans ; Motion Perception/physiology* ; Bayes Theorem ; Optic Flow ; Cues ; Vestibule, Labyrinth/physiology* ; Photic Stimulation ; Visual Perception/physiology*