AB061. Changes in eye movement strategies during a discrimination task in the presence of artificial central scotomas

Background:The goal of the present research was to study whether the presence of an artificial central scotoma resulted in changes in eye movement strategies over the course of multiple days of training.We wished to determine how central vision loss,similar to age macular degeneration(AMD),affects eye movements,specifically the foveal-target alignment.We also wished to determine if an invisible compared to a visible scotoma led to delayed or different strategies,given that AMD patients are mostly unaware of their condition as they are unconscious of the presence of their central scotoma.Methods:Eleven healthy participants(6 females,M=22.18,SD=1.94)were asked to perform a discrimination task,where they responded whether the orientation of an eccentric target(Gabor,10 deg to the left of fixation)was clockwise or counter-clockwise.The target was surrounded by four distractor Gabors,thus making discrimination more difficult using peripheral vision.The target’s orientation varied 10°clockwise to 10°counter-clockwise in 1°intervals.Each participant performed four blocks of 75 trials each per day over 10 days,the first day being a baseline as the participant were tested without any scotoma.We measured discrimination performance and precision(position of the eye in X and Y).Results:Results showed similar patterns of discrimination reaction time and accuracy as well as changes to eye position for both the visible and the invisible scotoma conditions.Discrimination time significantly decreased on the last day of training compared to the first(first day M=2,965 ms,last day M=1,567 ms,P<0.05),while accuracy increased though not significantly so(first day=87.4%,last day=93.15%).There was no change in the final horizontal(X)position of first saccade relative to the target(first=−0.4°,last=−0.13°)but there was a significant upward shift(first=0.08°vs.last=0.58°,P<0.05);participants shifted their eye position on the Y axis so that they were looking at a point slightly above the target.Conclusions:These findings suggest that the presence of an artificial central scotoma induces both changes in saccade planning mechanisms as well as changes in peripheral visual function,possibly attentional,resulting in improved discrimination performance.This study allows a better comprehension of eye movement and attentional strategies during central visual loss and provides insight into possible rehabilitation strategies.

Fifteen acute retrobulbar optic neuritis associated with COVID-19:A case report and review of literature

BACKGROUND A subtype of the Omicron variant of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is suggested to be responsible for the outbreak in Northern China since the quarantine was lifted in December 2022.The coronavirus disease 2019 virus is primarily responsible for the development of respiratory illnesses,however,it can present a plethora of symptoms affecting a myriad of body organs.This virus has been theorized to be linked to demyelinating lesions of the peripheral and central nervous system including transverse myelitis and acute retrobulbar optic neuritis(ARON).For example,magnetic resonance imaging(MRI)of the orbit and brain showed enlargement of the retrobulbar intraorbital segments of the optic nerve with high T2 signal,and no abnormalities were seen in the brain tissue.In this case series,we analyzed the connection between SARSCoV-2 infection and the onset of ARON.CASE SUMMARY Fifteen patients,and a teenage boy who did not have any pre-existing ocular or demyelinating diseases suddenly experienced a loss of vision after SARS-CoV-2 infection.The patients expressed a central scotoma and a fever as the primary concern.The results of the fundus photography were found to be normal.However,the automated perimetry and MRI scans showed evidence of some typical signs.Out of the 15 patients diagnosed with ARON after SARS-CoV-2 infection,only one individual tested positive for the aquaporin-4 antibody.CONCLUSION Direct viral invasion of the central nervous system and an immune-related process are the two primary causes of SARS-CoV-2-related ARON.

AB060.Peripheral attentional allocation during visual search in the presence of an artificial scotoma in younger and older adults

Background:Age related macular degeneration(AMD)is one of the main causes of vision loss in older adults,generating,in most cases,a central scotoma that reduces central visual acuity(Noble&Chaudhary,2010).People affected by AMD have to rely on peripheral visual information and would highly benefit from efficiently allocating their attention to the periphery.Indeed,attention can improve peripheral spatial resolution(Carrasco,Ling&Read,2004)and can be allocated to a certain expanse of space outside of the central visual span,known as the attentional span.Attentional span has been shown to be decreased in people with AMD with less attention allocated to the periphery and more to the central visual field(Cheong et al.,2008),however it remains unknown whether aging is also a contributing factor.Methods:Fourteen healthy younger(mean age=21.8 years,SD=1.5)and 8 older adults(mean age=69.6 years,SD=7.3)performed a pop-out and a serial version of a visual search task,in the presence of different sized gaze-contingent invisible and visible artificial central scotomata(no scotoma,3°diameter,5°and 7°).Participants were asked to indicate as quickly as possible whether a target was present or not among distractors whose number varied(16,32 or 64 objects).We wished to determine whether the size of the scotoma,occluding different degrees of central vision,affected visual search differently for younger vs.older participants.Results:Both the younger and older participants showed higher reaction times(RTs)to find the target for the serial version(M=2,074 ms for younger adults,M=3,853 ms for older adults)compared to the pop-out version(M=866 ms,M=1,475 ms,P<0.001)and for more distractors(32 distractors compared to 16,and 64 compared to 32,P<0.01).Older adults showed longer RTs than younger adults for both versions of the task(P<0.01).We found a significant effect of scotoma size on older adults(3°scotoma M=3,276 ms;7°scotoma M=3,877 ms,P<0.05),however,accurate performance was higher with no scotoma(96%vs.92%,P<0.05)in the pop-out search task.This suggests that older participants privileged a fast decision at the expense of performance in those cases.For the younger adults,RTs were higher in the serial search task in the presence of a scotoma(M=2,074 ms)compared to the control condition(M=1,665 ms,P>0.05).Conclusions:These results suggest that older adults take longer to perform visual search compared to younger adults and tend to use peripheral visual less than younger adults;larger central scotomas disrupted their performance but not that of younger participants,who performed equally well with different central scotoma sizes.These findings suggest that aging is a contributing factor in the decrease of the peripheral attentional span.