Retinal Shifts Research Articles

Comprehensive Review on the Use of Artificial Intelligence in Ophthalmology and Future Research Directions.

Having several applications in medicine, and in ophthalmology in particular, artificial intelligence (AI) tools have been used to detect visual function deficits, thus playing a key role in diagnosing eye diseases and in predicting the evolution of these common and disabling diseases. AI tools, i.e., artificial neural networks (ANNs), are progressively involved in detecting and customized control of ophthalmic diseases. The studies that refer to the efficiency of AI in medicine and especially in ophthalmology were analyzed in this review. We conducted a comprehensive review in order to collect all accounts published between 2015 and 2022 that refer to these applications of AI in medicine and especially in ophthalmology. Neural networks have a major role in establishing the demand to initiate preliminary anti-glaucoma therapy to stop the advance of the disease. Different surveys in the literature review show the remarkable benefit of these AI tools in ophthalmology in evaluating the visual field, optic nerve, and retinal nerve fiber layer, thus ensuring a higher precision in detecting advances in glaucoma and retinal shifts in diabetes. We thus identified 1762 applications of artificial intelligence in ophthalmology: review articles and research articles (301 pub med, 144 scopus, 445 web of science, 872 science direct). Of these, we analyzed 70 articles and review papers (diabetic retinopathy (N = 24), glaucoma (N = 24), DMLV (N = 15), other pathologies (N = 7)) after applying the inclusion and exclusion criteria. In medicine, AI tools are used in surgery, radiology, gynecology, oncology, etc., in making a diagnosis, predicting the evolution of a disease, and assessing the prognosis in patients with oncological pathologies. In ophthalmology, AI potentially increases the patient's access to screening/clinical diagnosis and decreases healthcare costs, mainly when there is a high risk of disease or communities face financial shortages. AI/DL (deep learning) algorithms using both OCT and FO images will change image analysis techniques and methodologies. Optimizing these (combined) technologies will accelerate progress in this area.

Retinal displacement following pars plana vitrectomy with silicone oil tamponade for rhegmatogenous retinal detachment.

To evaluate the frequency of retinal displacement after pars plana vitrectomy (PPV) using silicone oil tamponade in patients with rhegmatogenous retinal detachment (RRD). Patients with fresh RRD were enrolled in this prospective interventional case series. A standard 3-port PPV with silicone oil tamponade was performed in all cases. A complete ocular examination, optical coherence tomography and fundus autofluorescence (FAF) imaging were performed at 1 and 3months follow-up. Orthoptic examinations including synoptophore and light on-off tests were also performed at 3months. Twenty-three eyes from 23 patients with mean age of 56.6 ± 11 (range: 38-82) years were included. All patients were pseudophakic. Downward retinal displacement was found in 2 eyes (8.7%) showing hyperautofluorescent lines parallel to retinal vessels in FAF image. The patients with retinal displacement did not complain of metamorphopsia and did not show abnormality in orthoptic tests. Unintentional retinal shift following PPV with silicone oil tamponade for RRD is uncommon and might have little clinical significance.

Retinal vessel shift and its association with axial length elongation in a prospective observation in Japanese junior high school students.

PurposeTo investigate retinal vessel shift (RVS) and its association with axial length (AL) elongation in junior high school students.MethodsTotal 161 eyes of 161 healthy junior high school students were prospectively studied. Optical AL and anterior chamber depth (ACD) measurements, and fundus photography were performed in the first and third grades. Eyes of subjects in the first and third grade that had perfect matching among all the retinal vessels were allocated to the RVS(−) group, otherwise allocated to the RVS(+) group. In the RVS(+) group, the peripapillary retinal arteries angle (PRAA) was measured for quantitative analysis of RVS; the angle between the major retinal arteries. The variables related to PRAA were identified using model selection with the corrected Akaike information criterion.ResultsForty-two eyes (26.1%) were allocated to the RVS(+) group. There were seven patterns in the RVS of those in the RVS(+) group, including clockwise shift in the supra temporal area (5 eyes), infra temporal area (7 eyes), and nasal area (9 eyes); anticlockwise shift in the supra temporal area (7 eyes), infra temporal area (5 eyes), and nasal area (2 eyes); and distal shift in the temporal area (7 eyes). The optimal model for the PRAA narrowing included larger AL and body weight in the first grade, and greater AL elongation.ConclusionVarious (seven) RVS patterns were observed in about 25% of the junior high school students within two years. RVS was associated with AL elongation, and useful to reveal the mechanism of myopic retinal stretch.

Multimodal imaging of eyes with metamorphopsia after vitrectomy for rhegmatogenous retinal detachment.

Purpose:To assess the retinal features in eyes with postoperative metamorphopsia (POM) following rhegmatogenous retinal detachment (RRD) repair using multimodal imaging (MMI).Methods:In this cross-sectional; case-control study, patients after successful RRD repair following 25-gauge vitrectomy, clear vitreous cavity, and corrected distance visual acuity (CDVA)>20/200 were categorized using Amsler chart: cases with POM and controls without POM. MMI was performed on swept-source platform (Triton, Topcon Inc) and the confocal scanning laser ophthalmoscope system (Spectralis HRA, Heidelberg). The measures assessed were CDVA, morphological features on optical coherence tomography, autofluorescence, and multicolor imaging (MCI).Results:Thirty-nine eyes were included in each group. Cases had greater number of eyes with total RRD (P = 0.029) preoperatively; abnormal foveal contour (P = 0.036), ellipsoid zone (EZ) disruption (P < 0.001) and poorer postoperative CDVA (P = 0.046) as compared to controls. Outer retinal folds and retinal shift (unintentional translocation of retina after reattachment surgery for RRD) did not differ significantly between the groups (P = 0.48 and 0.35, respectively). On MCI, the distribution of detected ERM was similar between the groups (P = 0.25). Postoperative CDVA was significantly worse in eyes with POM.Conclusion:POM is affected by extent of RRD, postoperative foveal contour, and EZ status but not by retinal shift.

Long-term outcome of macular shift after retinal detachment repair.

This study aimed to evaluate the long-term change of postoperative retinal shift after pars plana vitrectomy for macular off retinal detachment. In this retrospective study, patients with retinal shift after pars plana vitrectomy for macula-off rhegmatogenous retinal detachment (RRD) were examined at 3weeks and 12months postoperatively. Fundus autofluorescence images were obtained to visualize retinal rotation. Best-corrected visual acuity was measured and metamorphopsia assessed using the Amsler grid. Nine patients with postoperative retinal shift were included in the study. Retinal shift decreased significantly in these patients, on average by 1.07° (range 0.52-1.62, p = 0.002) after 12months. However, more patients complained of distorted vision after 12months (odds ratio for change = 3.0, 95% CI: 0.24 to 157.49). The main reason was the new formation of an epiretinal membrane (odds ratio for change = infinity, 95% CI: 0.41 to infinity). There was no change in visual acuity observed (p = 0.16). Postoperative retinal shift after RRD repair decreases over a 1-year span. While retinal shift is the main cause for metamorphopsia in the early postoperative period, formation of an ERM is the main reason for distorted vision long term.

Displacement detection is suppressed by the post-saccadic stimulus

To establish a perceptually stable world despite the large retinal shifts caused by saccadic eye movements, the visual system reduces its sensitivity to the displacement of visual stimuli during saccades (e.g. saccadic suppression of displacement, SSD). Previous studies have demonstrated that inserting a temporal blank right after a saccade improves displacement detection performance. This ‘blanking effect’ suggests that visual information right after the saccade may play an important role in SSD. To understand the mechanisms underlying SSD, we here compare the effect of pre- and post-saccadic stimulus contrast on displacement detection during a saccade with and without inserting a blank. Our results show that observers’ sensitivity to detect visual displacement was reduced by increasing post-saccadic stimulus contrast, but a blank relieves the impairment. We successfully explain the results with a model proposing that parvo-pathway signals suppress the magno-pathway processes responsible for detecting displacements across saccades. Our results suggest that the suppression of the magno-pathway by parvo-pathway signals immediately after a saccade causes SSD, which helps to achieve the perceptual stability of the visual world across saccades.

Direction of Apparent Motion During Smooth Pursuit Is Determined Using a Mixture of Retinal and Objective Proximities.

Many studies have investigated various effects of smooth pursuit on visual motion processing, especially the effects related to the additional retinal shifts produced by eye movement. In this article, we show that the perception of apparent motion during smooth pursuit is determined by the interelement proximity in retinal coordinates and also by the proximity in objective world coordinates. In Experiment 1, we investigated the perceived direction of the two-frame apparent motion of a square-wave grating with various displacement sizes under fixation and pursuit viewing conditions. The retinal and objective displacements between the two frames agreed with each other under the fixation condition. However, the displacements differed by 180 degrees in terms of phase shift, under the pursuit condition. The proportions of the reported motion direction between the two viewing conditions did not coincide when they were plotted as a function of either the retinal displacement or of the objective displacement; however, they did coincide when plotted as a function of a mixture of the two. The result from Experiment 2 showed that the perceived jump size of the apparent motion was also dependent on both retinal and objective displacements. Our findings suggest that the detection of the apparent motion during smooth pursuit considers the retinal proximity and also the objective proximity. This mechanism may assist with the selection of a motion path that is more likely to occur in the real world and, therefore, be useful for ensuring perceptual stability during smooth pursuit.

Retinal Shift with Perfluorocarbon Liquid without Air-Fluid Exchange

A 61-year-old pseudophakic man who had pneumatic retinopexy 7 days prior, presented with counting fingers vision and a total rhegmatogenous retinal detachment with no proliferative vitreoretinopathy. He underwent 23-gauge pars plana vitrectomy and perfluorocarbon liquid (PFCL) injection. While PFCL was injected slowly, it was noted that subretinal fluid (SRF) was displaced inferiorly and temporally before exiting the retinal breaks (Fig A). One week postoperatively while PFCL was in the eye as a short-term tamponade, the retina was attached but with significant retinal displacement on fundus autofluorescence imaging in the direction of SRF flow (Fig B). PFCL removal was performed 1 week later (Fig C). The retinal displacement on FAF did not resolve (Fig D). (Magnified version of Fig A-D is available online at www.aaojournal.org).

Influence of Postoperative Posture on Macular Slippage after Macula-Off Retinal Detachment: A Randomized Controlled Trial.

IntroductionTo evaluate the effect of postoperative posture on the retinal shift after retinal detachment repair.MethodsPatients who underwent pars plana vitrectomy (PPV) for macula-off rhegmatogenous retinal detachment (RRD) were included prospectively in the current study. Patients were randomized into two groups: group A included patients who did a log roll postoperatively, and group B included patients who had to lie flat on their backs for 6 h postoperatively before moving into the end position. Patients in group A and patients in group B were reviewed after 3 weeks and after 6 weeks, respectively, and fundus autofluorescence images (FAF) were obtained to visualize the retinal rotation.ResultsThe sample included 50 eyes from 49 patients. Retinal shift occurred after RRD repair in 17 patients (34%). There was no statistically significant difference between the two groups (p = 0.94). Postoperative macular shift occurred significantly less often (p = 0.049) in participants in whom heavy fluid was used in the procedure. Metamorphopsia was reported postoperatively by 10 of 17 patients with retinal shift (p < 0.001).ConclusionIn our study, postoperative posture did not significantly influence postoperative macular slippage after RRD repair. The use of intraoperative heavy liquid appears to be associated with a lower occurrence of retinal shift.

The influence of retinal image motion on the perceptual grouping of temporally asynchronous stimuli.

Briefly presented stimuli can reveal the lower limit of retinal-based perceptual stabilization mechanisms. This is demonstrated in perceptual grouping of temporally asynchronous stimuli, in which alternate row or column elements of a regular grid are presented over two successive display frames with an imperceptible temporal offset. The grouping phenomenon results from a subtle shift between alternate grid elements due to incomplete compensation of small, fixational eye movements occurring between the two presentation frames. This suggests that larger retinal shifts should amplify the introduced shifts between alternate grid elements and improve grouping performance. However, large shifts are necessarily absent in small eye movements. Furthermore, shifts follow a random walk, making the relationship between shift magnitude and performance difficult to explore systematically. Here, we established a systematic relationship between retinal image motion and perceptual grouping by presenting alternate grid elements (untracked) during smooth pursuit of known velocities. Our results show grouping performance to improve in direct proportion to pursuit velocity. Any potential compensation by extraretinal signals (e.g., efference copy) does not seem to occur.

How to Prevent Retinal Shift after Rhegmatogenous Retinal Detachment Repair: A Prospective, Randomized Study

To evaluate the effect of intraoperative use of heavy liquid on retinal shift after retinal detachment repair. Prospective, randomized study. Patients who underwent pars plana vitrectomy for macula-off rhegmatogenous retinal detachment were included in the current study. Patients were randomized into 2 groups: group A included patients in whom heavy liquid was used during the procedure and group B included patients in whom no heavy liquid was used. Group A and B patients were reviewed after 3 weeks and after 6 weeks, respectively, and fundus autofluorescence (FAF) images were obtained to visualize the retinal rotation. Postoperative macular shift, visualized with FAF. A total of 50 eyes from 49 patients were included. Overall, retinal shift was observed in 17 patients (34%). Patients in whom heavy liquid was used during the procedure showed significantly less macular shift after surgery (P= 0.049). There was a strong association between retinal shift and postoperative symptoms of metamorphopsia. Ten of 17 patients with retinal shift reported distorted vision (P < 0.001). The use of intraoperative heavy liquid seems to be associated with lower occurrence of retinal shift after retinal detachment repair.

Feature-based attention across saccades: Pop-out in color search is spatiotopic.

Our perception of the world remains stable despite the retinal shifts that occur with each saccade. The role of spatial attention in matching pre- to postsaccadic visual information has been well established, but the role of feature-based attention remains unclear. In this study, we examined the transsaccadic processing of a color pop-out target. Participants made a saccade towards a neutral target and performed a search task on a peripheral array presented once the saccade landed. A similar array was presented just before the saccade and we analyzed what aspect of this preview benefitted the postsaccadic search task. We assessed the preview effect in the spatiotopic and retinotopic reference frames, and the potential transfer of feature selectivity across the saccade. In the first experiment, the target and distractor colors remained identical for the preview and the postsaccadic array and performance improved. The largest benefit was observed at the spatiotopic location. In the second experiment, the target and distractor colors were swapped across the saccade. All responses were slowed but the cost was least at the spatiotopic location. Our results show that the preview attracted spatial attention to the target location, which was then remapped, and suggest that previewed features, specifically colors, were transferred across the saccade. Furthermore, the preview induced a spatiotopic advantage regardless of whether the target switched color or not, suggesting that spatiotopy was established independently of feature processing. Our results support independent priming effects of features versus location and underline the role of feature-based selection in visual stability.

Transsaccadic transfer of distortion adaptation in a natural environment.

Spatially varying distortions in optical elements-for instance prisms and progressive power lenses-modulate the visual world disparately in different visual areas. Saccadic eye movements in such a complexly distorted environment thereby continuously alter the retinal location of the distortions. Yet the visual system achieves perceptual constancy by compensating for distortions irrespective of their retinal relocations at different fixations. Here, we assessed whether the visual system retains its plasticity to distortions across saccades to attain stability. Specifically, we tapped into reference frames of geometric skew-adaptation aftereffects to evaluate the transfer of retinotopic and spatiotopic distortion information across saccades. Adaptation to skew distortion of natural-image content was tested at retinotopic and spatiotopic locations after a saccade was executed between adaptation and test phases. The skew-adaptation information was partially transferred to a new fixation after a saccade. Significant adaptation aftereffects were obtained at both retinotopic and spatiotopic locations. Conceivably, spatiotopic information was used to counterbalance the saccadic retinal shifts of the distortions. Therefore, distortion processing in a natural visual world does not start anew at each fixation; rather, retinotopic and spatiotopic skew information acquired at previous fixations are preserved to mediate stable perception during eye movements.

Saccades Influence the Visibility of Targets in Rapid Stimulus Sequences: The Roles of Mislocalization, Retinal Distance and Remapping

Briefly presented targets around the time of a saccade are mislocalized towards the saccadic landing point. This has been taken as evidence for a remapping mechanism that accompanies each eye movement, helping maintain visual stability across large retinal shifts. Previous studies have shown that spatial mislocalization is greatly diminished when trains of brief stimuli are presented at a high frequency rate, which might help to explain why mislocalization is rarely perceived in everyday viewing. Studies in the laboratory have shown that mislocalization can reduce metacontrast masking by causing target stimuli in a masking sequence to be perceived as shifted in space towards the saccadic target and thus more easily discriminated. We investigated the influence of saccades on target discrimination when target and masks were presented in a rapid serial visual presentation (RSVP), as well as with forward masking and with backward masking. In a series of experiments, we found that performance was influenced by the retinal displacement caused by the saccade itself but that an additional component of un-masking occurred even when the retinal location of target and mask was matched. These results speak in favor of a remapping mechanism that begins before the eyes start moving and continues well beyond saccadic termination.

Impact of stride-coupled gaze shifts of walking blowflies on the neuronal representation of visual targets.

During locomotion animals rely heavily on visual cues gained from the environment to guide their behavior. Examples are basic behaviors like collision avoidance or the approach to a goal. The saccadic gaze strategy of flying flies, which separates translational from rotational phases of locomotion, has been suggested to facilitate the extraction of environmental information, because only image flow evoked by translational self-motion contains relevant distance information about the surrounding world. In contrast to the translational phases of flight during which gaze direction is kept largely constant, walking flies experience continuous rotational image flow that is coupled to their stride-cycle. The consequences of these self-produced image shifts for the extraction of environmental information are still unclear. To assess the impact of stride-coupled image shifts on visual information processing, we performed electrophysiological recordings from the HSE cell, a motion sensitive wide-field neuron in the blowfly visual system. This cell has been concluded to play a key role in mediating optomotor behavior, self-motion estimation and spatial information processing. We used visual stimuli that were based on the visual input experienced by walking blowflies while approaching a black vertical bar. The response of HSE to these stimuli was dominated by periodic membrane potential fluctuations evoked by stride-coupled image shifts. Nevertheless, during the approach the cell’s response contained information about the bar and its background. The response components evoked by the bar were larger than the responses to its background, especially during the last phase of the approach. However, as revealed by targeted modifications of the visual input during walking, the extraction of distance information on the basis of HSE responses is much impaired by stride-coupled retinal image shifts. Possible mechanisms that may cope with these stride-coupled responses are discussed.

No perisaccadic mislocalization with abruptly cancelled saccades.

Every saccadic eye movement that we make changes the image of the world on our retina. Yet, despite these retinal shifts, we still perceive our visual world to be stable. Efference copy from the oculomotor system to the visual system has been suggested to contribute to this stable percept, enabling the brain to anticipate the retinal image shifts by remapping the neural image. A psychophysical phenomenon that has been linked to this predictive remapping is the mislocalization of a stimulus flashed around the time of a saccade. If this mislocalization is initiated by saccade preparation, one should also observe localization errors when a saccade is planned, but abruptly aborted just before its execution. We tested this hypothesis in human subjects using a novel paradigm that combines a flash localization task with a countermanding component that occasionally requires saccade cancellation. Surprisingly, we found no trace of mislocalization, even for saccades cancelled close to the point of no return. This strongly suggests that the actual execution of the saccade is a prerequisite for the typical localization errors, which rejects various models and constrains neural substrates. We conclude that perisaccadic mislocalization is not a direct consequence of saccade preparation, but arises after saccade execution when the flash location is constructed from memory.

Single-Molecule Observation of the Ligand-Induced Population Shift of Rhodopsin, A G-Protein-Coupled Receptor

Rhodopsin is a G-protein-coupled receptor, in which retinal chromophore acts as inverse-agonist or agonist depending on its configuration and protonation state. Photostimulation of rhodopsin results in a pH-dependent equilibrium between the active state (Meta-II) and its inactive precursor (Meta-I). Here, we monitored conformational changes of rhodopsin using a fluorescent probe Alexa594 at the cytoplasmic surface, which shows fluorescence increase upon the generation of active state, by single-molecule measurements. The fluorescence intensity of a single photoactivated rhodopsin molecule alternated between two states. Interestingly, such a fluorescence alternation was also observed for ligand-free rhodopsin (opsin), but not for dark-state rhodopsin. In addition, the pH-dependences of Meta-I/Meta-II equilibrium estimated by fluorescence measurements deviated notably from estimates based on absorption spectra, indicating that both Meta-I and Meta-II are mixtures of two conformers. Our observations indicate that rhodopsin molecules intrinsically adopt both active and inactive conformations, and the ligand retinal shifts the conformational equilibrium. These findings provide dynamical insights into the activation mechanisms of G-protein-coupled receptors.

A Retinotopic Attentional Trace after Saccadic Eye Movements: Evidence from Event-related Potentials

Saccadic eye movements are a major source of disruption to visual stability, yet we experience little of this disruption. We can keep track of the same object across multiple saccades. It is generally assumed that visual stability is due to the process of remapping, in which retinotopically organized maps are updated to compensate for the retinal shifts caused by eye movements. Recent behavioral and ERP evidence suggests that visual attention is also remapped, but that it may still leave a residual retinotopic trace immediately after a saccade. The current study was designed to further examine electrophysiological evidence for such a retinotopic trace by recording ERPs elicited by stimuli that were presented immediately after a saccade (80 msec SOA). Participants were required to maintain attention at a specific location (and to memorize this location) while making a saccadic eye movement. Immediately after the saccade, a visual stimulus was briefly presented at either the attended location (the same spatiotopic location), a location that matched the attended location retinotopically (the same retinotopic location), or one of two control locations. ERP data revealed an enhanced P1 amplitude for the stimulus presented at the retinotopically matched location, but a significant attenuation for probes presented at the original attended location. These results are consistent with the hypothesis that visuospatial attention lingers in retinotopic coordinates immediately following gaze shifts.

Looking at Op Art: Gaze Stability and Motion Illusions

Various Op artists have used simple geometrical patterns to create the illusion of motion in their artwork. One explanation for the observed illusion involves retinal shifts caused by small involuntary eye movements that observers make while they try to maintain fixation. Earlier studies have suggested a prominent role of the most conspicuous of these eye movements, small rapid position shifts called microsaccades. Here, we present data that could expand this view with a different interpretation. In three experiments, we recorded participants' eye movements while they tried to maintain visual fixation when being presented with variants of Bridget Riley's Fall, which were manipulated such as to vary the strength of induced motion. In the first two experiments, we investigated the properties of microsaccades for a set of stimuli with known motion strengths. In agreement with earlier observations, microsaccade rates were unaffected by the stimulus pattern and, consequently, the strength of induced motion illusion. In the third experiment, we varied the stimulus pattern across a larger range of parameters and asked participants to rate the perceived motion illusion. The results revealed that motion illusions in patterns resembling Riley's Fall are perceived even in the absence of microsaccades, and that the reported strength of the illusion decreased with the number of microsaccades in the trial. Together, the three experiments suggest that other sources of retinal image instability than microsaccades, such as slow oculomotor drift, should be considered as possible factors contributing to the illusion.

Binocular Onset Rivalry at the Time of Saccades and Stimulus Jumps

Recent studies suggest that binocular rivalry at stimulus onset, so called onset rivalry, differs from rivalry during sustained viewing. These observations raise the interesting question whether there is a relation between onset rivalry and rivalry in the presence of eye movements. We therefore studied binocular rivalry when stimuli jumped from one visual hemifield to the other, either through a saccade or through a passive stimulus displacement, and we compared rivalry after such displacements with onset and sustained rivalry. We presented opponent motion, orthogonal gratings and face/house stimuli through a stereoscope. For all three stimulus types we found that subjects showed a strong preference for stimuli in one eye or one hemifield (Experiment 1), and that these subject-specific biases did not persist during sustained viewing (Experiment 2). These results confirm and extend previous findings obtained with gratings. The results from the main experiment (Experiment 3) showed that after a passive stimulus jump, switching probability was low when the preferred eye was dominant before a stimulus jump, but when the non-preferred eye was dominant beforehand, switching probability was comparatively high. The results thus showed that dominance after a stimulus jump was tightly related to eye dominance at stimulus onset. In the saccade condition, however, these subject-specific biases were systematically reduced, indicating that the influence of saccades can be understood from a systematic attenuation of the subjects' onset rivalry biases. Taken together, our findings demonstrate a relation between onset rivalry and rivalry after retinal shifts and involvement of extra-retinal signals in binocular rivalry.