Ability of swept source OCT to detect retinal changes in patients with bipolar disorder

Can retinal nerve fiber layer (RNFL) thickness be a marker for distinguishing bipolar depression from unipolar depression?

OBJECTIVE

We aimed to compare retinal nerve fiber layer (RNFL) thickness and ganglion cell complex (GCC) thickness in bipolar disorder (BD) and major depressive disorder (MDD).

METHOD

The study included thirty MDD, thirty-two BD participants in depressive episode, and thirty-seven controls matched according to age, gender, body mass index (BMI), and smoking status. Optic coherence tomography (OCT) measurements were performed for both participants and controls. The RNFL and GCC thickness were measured and recorded automatically by a spectral OCT device. Participants were also subjected to Hamilton Depression Rating Scale (HAM-D).

RESULTS

RNFL superior thickness was significantly lower in BD participants, compared to the MDD participants and controls (p = 0.001). GCC inferior (p = 0.022) and inferonasal (p = 0.005) thickness were detected lower in BD group, compared to the control groups. In the BD group, HAM-D scores were negatively correlated with RNFL-temporal (p = 0.049, r= -0.357), GCC inferotemporal (p = 0.02, r= -0.416) and superotemporal thickness (p = 0.002, r= -0.546).

CONCLUSIONS

RNFL thickness were lower in BD participants compared to the MDD and controls and, GCC thickness were lower in BD participants compared to the controls. Our findings support the hypothesis that neurodegeneration is part of the pathogenesis of BD. Future research are needed to confirm the lack of RNFL thickness in MDD, which could have immediate therapeutic consequences as well as implications for distinguishing BD from MDD.

Optical coherence tomography angiography in patients with bipolar disorder and major depressive disorder

BACKGROUND

Cerebral microvascular dysfunction is a promising area for research into the pathogenesis of major depressive disorder (MDD) and bipolar disorder (BD). Despite the scientific and clinical potential of studying microvascular dysfunction, progress in this area has long been hampered by the lack of methods to study microvessels intravitally.

AIMS

The aim of the present study was to search for potential optical coherence tomography (OCT) and OCT-angiography (OCTA) biomarkers of BD and MDD.

METHODS

One hundred and five consecutive patients with a current depressive episode were enrolled in the study (39 - BD and 66 - MDD). In addition, forty-one generally healthy subjects were enrolled as a control group. Only the right eye was examined in all subjects. Structural OCT and OCTA scans with signal strength ≥7 were included.

RESULTS

Structural OCT measurements showed no significant differences between the groups. OCTA measurements of foveal avascular zone (FAZ), area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group. Several significant differences were found between the BD and control groups. In the BD group, the FAZ of the deep capillary plexus was increased, reflecting a reduction in capillary perfusion in the central subfield of this plexus.

CONCLUSIONS

OCTA measurements of FAZ, area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group.

Neuroretinal Alterations in Schizophrenia and Bipolar Disorder: An Updated Meta-analysis

Schizophrenia (SZ) and bipolar disorder (BD) are characterized by major symptomatic, cognitive, and neuroanatomical changes. Recent studies have used optical coherence tomography (OCT) to investigate retinal changes in SZ and BD, but their unique and shared changes require further evaluation. Articles were identified using PubMed and Google Scholar. 39 studies met the inclusion criteria. Diagnostic groups were proband (SZ/BD combined), SZ, BD, and healthy control (HC) eyes. Meta-analyses utilized fixed and random effects models when appropriate, and publication bias was corrected using trim-and-fill analysis ("meta" package in R). Results are reported as standardized mean differences with 95% CIs. Data from 3145 patient eyes (1956 SZ, 1189 BD) and 3135 HC eyes were included. Studies identified thinning of the peripapillary retinal nerve fiber layer (pRNFL, overall and in 2 subregions), m-Retina (overall and all subregions), mGCL-IPL, mIPL, and mRPE in SZ patients. BD showed thinning of the pRNFL (overall and in each subregion), pGCC, and macular Retina (in 5 subregions), but no changes in thickness or volume for the total retina. Neither SZ nor BD patients demonstrated significant changes in the fovea, mRNFL, mGCL, mGCC, mINL, mOPL, mONL, or choroid thicknesses. Moderating effects of age, illness duration, and smoking on retinal structures were identified. This meta-analysis builds upon previous literature in this field by incorporating recent OCT studies and examining both peripapillary and macular retinal regions with respect to psychotic disorders. Overall, this meta-analysis demonstrated both peripapillary and macular structural retinal abnormalities in people with SZ or BD compared with HCs.

Optic nerve head neurovascular assessments in patients with schizophrenia: A cross-sectional study

Objective

The retina is a protrusion of the brain, so researchers have recently proposed retinal changes as a new marker for studying central nervous system diseases. To investigate optic nerve head neurovascular structure assessed by optical coherence tomography angiography (OCTA) in schizophrenia compared to healthy subjects.

Methods

The study was conducted from 2019 to 2021 at the Ibn Sina Psychiatric Hospital in Mashhad, Iran. We enrolled 22 hospitalized known cases of schizophrenia, treated with risperidone as an antipsychotic drug, and 22 healthy subjects. The two groups were matched in age and gender. In the schizophrenic group, the positive and negative syndrome scale test was used to assess the illness severity. All subjects underwent complete ophthalmic evaluations and OCTA imaging.

Results

We found that the cup/disc area ratio, vertical cup/disc ratio, and horizontal cup/disc ratio are significantly higher in patients with schizophrenia than in healthy subjects (with p-values of 0.019, 0.015, and 0.022, respectively). No statistically significant difference in the peripapillary retinal nerve fiber layer and vascular parameters of the optic nerve head was observed between schizophrenia and healthy groups.

Conclusion

We found evidence regarding the difference in the optic nerve head tomographic properties in schizophrenia compared to healthy subjects. However, ONH vascular parameters showed no significant difference. More studies are needed for a definite conclusion.

Assessment of metacognition and retinal optical coherence tomography findings in shift workers

It is known that working in the shift system, especially the night shift, affects physical, mental, and social well-being. We investigated the changes in the inner retinal layers and choroidal layer of the eyes of nurses working night and day shifts using optical coherence tomography (OCT). We also explored the effect of night shift work on metacognition and the relationships between these variables. A total of 79 nurses participated in the study, of whom 40 worked night shifts. The researcher gave the participants sociodemographic information and the Metacognition Questionnaire-30 (MCQ-30) form. Retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL) thickness, inner nuclear layer (INL) thickness, inner plexiform layer (IPL) thickness, central macular thickness (CMT), and subfoveal choroidal thickness (SFCT) were measured with OCT. It was found that the level of metacognitive activity associated with cognitive confidence was higher (p = 0.044) for nurses who worked night shifts and that the level of metacognitive activity associated with cognitive awareness was lower (p = 0.015) for nurses who worked night shifts. RNFL-nasal superior (NS) thickness was lower in night shift workers than the day shift group (p = 0.017). Our study revealed significant relationships between metacognition and the OCT findings among night and day shift workers. Our study revealed that RNFL measurements and metacognitive activity may differ and there may be a relationship between these parameters in nurses who work shifts. Further research is needed to investigate the long-term effects of night shift work on retinal health.

Optical Coherence Tomography Findings in Bipolar Disorder Patients and the Related Factors

Background

This study's purpose is to determine the effects of current episode and the mood stabilizers on chorioretinal layer thicknesses of bipolar disorder (BD) patients using spectral-domain optical coherence tomography (SD-OCT).

Methods

Sixty-seven patients were diagnosed with BD I and using lithium (Li) or valproic acid (VPA), of whom 20 were manic, 24 were depressive, and 23 were in remission, and 49 healthy individuals were included in the study. Peripapillary retinal nerve fiber layer (RNFL), ganglion cell layer, and macular thicknesses of the participants were measured automatically using SD-OCT, and their choroid layer thicknesses were measured manually using the depth imaging mode of SD-OCT. Statistical analysis of the data was performed using Statistical Package for the Social Sciences version 23.0.

Results

The patient group's mean age was 39.78 ± 11.78, and the control group's mean age was 42.06 ± 12.10. The mean disease duration was 13.22 ± 8.23 in the patient group, and 26 patients were using Li. While peripapillary RNFL thicknesses were lower in the patient group (P < .05), other layer measurements were similar between the groups. Moreover, the episodes experienced by BD patients did not affect chorioretinal SD-OCT measurements. The patients on VPA had significantly lower RNFL thicknesses compared to the control and the Li groups, and all chorioretinal measurements were similar between the Li and the control groups.

Conclusion

As a result of the study, it was established that neurodegenerative processes play a role in the pathophysiology of BD and the usage of Li is protective against the neurodegeneration of RNFL. Retinal changes measured with SD-OCT can be used for the diagnosis and prognosis of BD and for evaluating responses to mood stabilizers.

A systematic review and meta-analysis of optical coherence tomography studies in schizophrenia, bipolar disorder and major depressive disorder

OBJECTIVES

Due to the common neurodevelopmental origin and easy accessibility, the retina serves as a surrogate marker for changes in the brain. Hence, Optical Coherence Tomography (OCT), a tool to examine the neuronal layers of retina has gained importance in investigating psychiatric disorders. Several studies in the last decade have reported retinal structural alterations in schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). However, the findings are inconsistent. Hence, we conducted a meta-analysis to investigate alterations in OCT parameters in patients with SCZ, BD and MDD.

METHODS

We searched electronic databases for studies that examined OCT parameters in patients with SCZ, BD and MDD published up to January 2023. The primary outcome measures were thickness and volumes of the retinal Nerve Fibre Layer (RNFL). We conducted meta-analysis using a random effects model.

RESULTS

The searches yielded 2638 publications of which 43 studies were included in the final analysis across all disorders. Compared to controls, the RNFL was thinner in SCZ patients (SMD = -0.37, p = <0.001) and BD patients (SMD = -0.67, p = < 0.001), but not in MDD patients (SMD = -0.08, p = 0.54). On quadrant wise analysis, temporal quadrant RNFL was thinner in SCZ but not in BD, while all other quadrants were thinner in both SCZ and BD.

CONCLUSION

We found significant reductions in RNFL thickness in SCZ and BD, but not in MDD. The differential involvement in various quadrants and parameters across the disorders has potential implications for using retinal parameters as a diagnostic biomarker.

Choroidal Structural Alterations and Choroidal Vascularity Index in Bipolar Disorder Patients

PURPOSE

The aim of this study was to compare bipolar disorder (BD) patients with age- and sex-matched healthy individuals in order to assess the choroidal structural alterations, retinal nerve fiber layer (RNFL) thickness, and retinal changes in BD patients using encanhed depth imaging optic coherence tomography (EDI-OCT).

METHOD

For this research, 39 eyes of BD patients and 36 eyes of age-matched healthy volunteers were used. Five locations were used to assess the choroidal thickness (CT): subfoveal, 500 µm nasal and 1500 µm nasal to the fovea, 500 µm temporal and 1500 µm temporal to the fovea. Image-J was used to determine the total choroidal area (TCA), luminal area (LA), and choroidal vascularity index (CVI). The Spectralis-OCT device was used to evaluate the central macular thickness (CMT), retinal nerve fiber layer (RNFL), and ganglion cell layer (GCL). The data were statistically compared.

RESULTS

BD patients had significantly decreased subfoveal, nasal, and temporal CTs than controls (for all three, p = 0.0001). The results of CMT and GCL were found to be thinner than controls. (for all p=0.0001) In comparison to the controls, the mean TCA and LA were decreased in the BD group. (p=0.0001, p=0.0001  respectively,).  Between the RNFL and CVI values in the BD and control groups, there was no statistically significant difference (p>0.05).

CONCLUSION

The results of this investigation showed that the retina and choroid of patients with BD had considerable anatomical changes.

Optical coherence tomography angiography in patients with euthymic bipolar disorder

OBJECTIVE

The number of studies conducted on the evaluation of retinal microvascularity in patients with Bipolar Disorder (BD) is very few. Therefore, in the present study it was aimed to provide a significant diagnostic support and to better understand the relationship between BD and vascular changes by making vascular measurements with Optical Coherence Tomography Angiography (OCTA).

METHOD

The statistical analysis was performed by comparing OCTA measurements of 48 eyes of 48 euthymic patients followed up with a diagnosis of BD and in remission for at least 6 months, and 45 eyes of 45 age-matched healthy volunteers in the control group. Among the OCTA measurements compared were retinal vessel density analysis, foveal avascular zone measurements, retinal nerve fiber layer, radial peripapillary capillary plexus, ganglion cell-inner plexiform layer values.

RESULTS

In the multivariate regression model, such variables as nasal quadrant of retinal nerve fiber layer, inferior and nasal quadrants of radial peripapillary capillary plexus and superficial vessel density variables were determined to have a significant and independent effect in differentiating patients with BD from the participants in the healthy control group.

CONCLUSION

In the present study, for the first time, the OCTA method was used to compare both retinal neurodegeneration and vascularization measurements in those in the BD and the healthy groups. That the effects of drugs other than mood stabilizers were not taken into account is among the limitations of our study.

Retinal changes in bipolar disorder as an endophenotype candidate: Comparison of OCT-detected retinal changes in patients, siblings, and healthy controls

Optical coherence tomography (OCT) is a non-invasive imaging technique that detects retinal changes reflecting neurodegeneration. In recent studies in patients with bipolar disorder (BD) abnormal OCT findings have shown. In this study, we aimed to investigate the retinal changes in BD patients and their healthy siblings (HS) by comparing them with the healthy control (HC) group and to explore these findings as potential endophenotype candidates. 31 patients with BD, 31 age-matched HSs and 46 HCs were included and peripapillary retinal nerve fiber layer (RNFL), ganglion cell layer (GCL)+inner plexiform layer (IPL) and macular volume (MV) thicknesses were measured by OCT. The relationship between disease severity parameters, functionality and OCT measurements in the patient group was also investigated. In results, the mean RNFL thicknesses did not differ between groups. All GCL+IPL thicknesses were found to be significantly lower in the patient and sibling groups compared to the HCs. GCL+IPL thicknesses were significantly correlated with functionality of patients and severity of the disorder. Our findings suggest that analysis of retinal layers with OCT may be a beneficial indicator to show neuronal changes in BD and GCL+IPL may be a suitable endophenotype candidate.

Sex-Specific Changes in Choroid Vasculature Among Patients with Schizophrenia and Bipolar Disorder

Purpose

While structural changes within the retina of psychosis patients have been established, no detailed studies of choroidal microvasculature in these patients have been performed. Given evidence of microvascular disruption in psychosis patients, this study sought to determine whether there exists evidence of microvascular disruption in the choroids in these patients.

Methods

Fifty-six subjects (20 controls and 36 psychosis patients) were recruited from April 2018 to February 2020. Five were excluded due to imaging artifact or missing demographic information. Swept-source optical coherence tomography angiography (SS-OCTA) images were obtained. Choroid vascular enface images (12 mm × 9mm) were exported every 2.6 μm from Bruch’s membrane to the choroid–scleral interface from Topcon to ImageJ. The images were binarized using Otsu’s method, signal from the optic disk and retinal vasculature was removed, and average choroid vascular density (CVD) was calculated as the average of percent area occupied by choroidal vasculature across images in the stack. Choroid vascular volume (CVV) was calculated as the CVD multiplied by maximum CT and image area. During image analysis, study staff were blinded to the phenotype of the study subjects.

Results

Compared with same-sex controls, male psychiatric patients had significantly lower CVD. Compared with same-sex controls, female psychiatric patients had significantly lower maximum CT with correspondingly decreased CVV, after adjusting for age. When all psychiatric patients were compared with all healthy controls, no significant differences in CT, CVD, or CVV were noted.

Conclusion

These results suggest that the pathogenesis of psychotic illness affects choroidal microvasculature in a sex-specific manner.

Ganglion cell complex thickness changes in patients with different states of bipolar disorder

OBJECTIVES

Neuroimaging studies in patients with bipolar disorder have suggested that a neuropathological process may be effective in this disease. Neurodegenerative changes in the retina can be followed by optical coherence tomography, a non-invasive imaging method that allows in vivo visualization of the retinal layers. The aim of this study was to investigate the possible differences in optical coherence tomography parameters during euthymic, manic, and depressive episodes in patients diagnosed with bipolar disorder.

METHODS

A total of 150 patients with bipolar disorder were included in the study, divided into three groups (50 patients in a euthymic state, 50 patients in a manic state, and 50 patients in a depressive state) and compared with 50 healthy controls. Ganglion cell complex thickness was measured with automated macular segmentation software of spectral-domain optical coherence tomography.

RESULTS

Ganglion cell complex thicknesses were thicker in all quadrants in patient groups than the control group but the differences were significant in perifoveal superior and perifoveal inferior quadrants (p < 0.001, p < 0.001). There were no differences in ganglion cell complex thickness among the patient groups (p > 0.05).

CONCLUSION

The evaluation of ganglion cell complex thickness by spectral-domain optical coherence tomography may give a clue for monitoring neurodegenerative changes in patients with bipolar disorder.

Evaluation of progressive retinal degeneration in Bipolar disorder patients over a period of 5 years

PURPOSE

To quantify visual and retinal changes in patients with bipolar disorder (BD) over 5 years, compared with controls.

METHODS

Thirty-eight patients with BD and 122 healthy subjects underwent visual acuity (VA) evaluation, contrast sensitivity vision testing (CSV) with the Pelli Robson and CSV 1000E tests, and retinal thicknesses measurement (ganglion cell layer - GCL- and retinal nerve fiber layer -RNFL-) using Spectralis Optical Coherence Tomography (OCT). All subjects were re-evaluated after 5 years. The relationship between progressive structural changes and disease duration was analysed.

RESULTS

Visual function parameters in BD patients remained unchanged during the follow up period. A progressive decrease affecting macular and peripapillary RNFL thickness (p < 0.050) was observed in patients. Progressive changes in BD were more pronounced when compared with healthy controls (p < 0.050). A significant correlation between GCL thickness changes and disease duration was found (GCL outer temporal, r=-0.680, p = 0.016; GCL central, r=-0.540, p = 0.038).

CONCLUSIONS

Progressive axonal loss was detected in BD patients. Visual function parameters were not affected after the 5-year follow up. Despite observed changes in the neuroretina of patients with BD, axonal degeneration in these patients seemed to be mild and might be slowed down by other factors such as BD treatments.

Bipolar disorders and retinal electrophysiological markers (BiMAR): Study protocol for a comparison of electroretinogram measurements between subjects with bipolar disorder and a healthy control group

BACKGROUND

Bipolar disorders (BD) is a common, chronic and disabling psychiatric condition. In addition to being characterized by significant clinical heterogeneity, notable disturbances of sleep and cognitive function are frequently observed in all phases of the disease. Currently, there is no readily available biomarker in current clinical practice to help diagnose or predict the disease course. Thus, identification of biomarkers in BD is today a major challenge. In this context, the study of electrophysiological biomarkers based on electroretinogram (ERG) measurements in BD seems highly promising. The BiMAR study aims to compare electrophysiological data measured with ERG between a group of euthymic patients with BD and a group of healthy control subjects. Secondarily, we will also describe the existing potential relationship between clinical, sleep and neuropsychological phenotypes of patients and electrophysiological data.

METHODS

The BiMAR study is a comparative and monocentric study carried out at the Expert Center for BD in Nancy, France. In total, 70 euthymic adult patients with BD and 70 healthy control subjects will be recruited. Electrophysiological recordings with ERG and electroencephalogram (EEG) will be performed with a virtual reality headset after a standardized clinical evaluation to all participants. Then, an actigraphic monitoring of 21 consecutive days will be carried out. At the end of this period a neuropsychological evaluation will be performed during a second visit. The primary outcome will be electrophysiological measurements with ERG flash and pattern. Secondary outcomes will be EEG data, sleep settings, clinical and neuropsychological assessments. For patients only, a complementary ancillary study, carried out at the University Hospital of Nancy, will be proposed to assess the retinal structure and microvascularization using Optical Coherence Tomography. Recruitment started in January 2022 and will continue until the end of July 2023.

DISCUSSION

The BiMAR study will contribute to identifying candidate ERG electrophysiological markers for helping the diagnosis of BD and identify subgroups of patients with different clinical profiles. Eventually, this would allow earlier diagnosis and personalized therapeutic interventions.

CLINICAL TRIAL REGISTRATION

The study is registered at Clinicaltrials.gov, NCT05161546, on 17 December 2021 (https://clinicaltrials.gov/ct2/show/NCT05161546).

The relation of optical coherence tomography findings with oxidative stress parameters in patients with bipolar disorder and unaffected first-degree relatives

BACKGROUND

We aimed to evaluate the optical coherence tomography(OCT) findings and oxidative stress parameters in patients with bipolar disorder(BD) and their unaffected first-degree relatives(FDRs) and to explore OCT findings and oxidative stress parameters as potential endophenotype candidates.

METHODS

Fifty patients with BD, 40 FDRs of BD, and 50 healthy controls(HCs) were included. OCT was performed to measure peripapillary retinal nerve fiber layer(RNFL), ganglion cell layer(GCL), inner plexiform layer(IPL), central macular, and minimum foveal thicknesses(CMT and MFT), choroidal thickness(ChT). 4-hydroxy-2-nonenal(HNE), total thiol(TT), native thiol(NT), total oxidant status(TOS), total antioxidant status(TAS), disulfide(DIS) and oxidative stress index(OSI) were measured from serum samples.

RESULTS

TOS was higher patients with BD and FDRs than HCs (p < .001 and p = .012, respectively). OSI, DIS, HNE levels were higher patients with BD and FDRs than HCs (p < .001). TAS, TT, NT levels were lower patients and FDRs than HCs (p < .001). MFT of patients was thinner than HCs (p = .001). CMT of patients was thinner than HCs (p = .006); the same trend was observed in FDRs but did not reach the statistical significance level (p = .07). The groups did not differ on RNFL and choroidal thickness or GCL and IPL volume.

LIMITATIONS

Evaluation of only a few retinal layers.

CONCLUSIONS

TOS, TAS, OSI, TT, NT, DIS, HNE can be useful endophenotype biomarkers in BD. Among the OCT findings, CMT was determined as the closest parameter to being an endophenotype biomarker. Our study corroborates that oxidative stress parameters are more effective than OCT findings in endophenotype studies.

Assessment of Optical Coherence Tomography Findings in Adults with Attention Deficit Hyperactivity Disorder: A Case-Control Study

Background

To assess retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness using optical coherence tomography in attention deficit hyperactivity disorder adults on regular methylphenidate treatment, comparing them to healthy controls.

Methods

A total of 33 attention deficit hyperactivity disorder adults and 31 healthy subjects, matched for age, gender, and education (control group), were included in this study. Retinal nerve fiber layer and ganglion cell-inner plexiform layer thickness of both eyes were measured using optical coherence tomography, and symptom severity was evaluated using Adult Attention Deficit Hyperactivity Disorder Self-Report Scale and Wender Utah Rating Scale.

Results

There was no significant difference in retinal nerve fiber layer thickness between the attention deficit hyperactivity disorder and control groups (P > .05). Thinner ganglion cell-inner plexiform layer total (P = .044), inferior (P = .012), and inferior nasal quadrant thickness (P = .049) were observed in attention deficit hyperactivity disorder patients as compared to the controls.

Conclusion

Findings detected thinner ganglion cell-inner plexiform layer in some quadrants of attention deficit hyperactivity disorder adults, indicating an early disorder in retinal structure development. Whether retinal structures are sensitive attention deficit hyperactivity disorder biomarkers should be supported and investigated in future multimodal studies.

Analysis of the Peripapillary and Macular Regions Using OCT Angiography in Patients with Schizophrenia and Bipolar Disorder

PURPOSE

To measure RNFL and vasculature around the optic disc and in the macula in patients with schizophrenia (SZ) and bipolar disorder (BD) using optical coherence tomography angiography (OCTA).

METHODS

24 eyes of patients with SZ and 16 eyes of patients with BD as well as 30 eyes of healthy subjects were examined with OCTA. The radiant peripapillary capillary (RPC) density and RNFL thickness were measured in the peripapillary area. Moreover, macular thickness and vessel density were measured in both superficial and deep layers.

RESULTS

Significantly decreased values of vessel density in the macular deep vascular complex were found in the eyes of patients with SZ, compared to BD and the control group. The macular thickness in the whole vascular complex and in the fovea was significantly lower in SZ and BD group than in the control group. The radiant peripapillary vascular density and RNFL thickness were similar across groups.

CONCLUSIONS

The retinal microvascular dysfunction occurs in the macula in patients with SZ and BD, but not around optic disc. OCTA can become an essential additional diagnostic tool in detection of psychiatric disorders.

Automatic Diagnosis of Bipolar Disorder Using Optical Coherence Tomography Data and Artificial Intelligence

Background: The aim of this study is to explore an objective approach that aids the diagnosis of bipolar disorder (BD), based on optical coherence tomography (OCT) data which are analyzed using artificial intelligence. Methods: Structural analyses of nine layers of the retina were analyzed in 17 type I BD patients and 42 controls, according to the areas defined by the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. The most discriminating variables made up the feature vector of several automatic classifiers: Gaussian Naive Bayes, K-nearest neighbors and support vector machines. Results: BD patients presented retinal thinning affecting most layers, compared to controls. The retinal thickness of the parafoveolar area showed a high capacity to discriminate BD subjects from healthy individuals, specifically for the ganglion cell (area under the curve (AUC) = 0.82) and internal plexiform (AUC = 0.83) layers. The best classifier showed an accuracy of 0.95 for classifying BD versus controls, using as variables of the feature vector the IPL (inner nasal region) and the INL (outer nasal and inner inferior regions) thickness. Conclusions: Our patients with BD present structural alterations in the retina, and artificial intelligence seem to be a useful tool in BD diagnosis, but larger studies are needed to confirm our findings.

Retinal structural changes in mood disorders: The optical coherence tomography to better understand physiopathology?

BACKGROUND

Mood disorders are particularly common, disabling conditions. Diagnosis can be difficult as it may involve different pathophysiological assumptions. This could explain why such disorders are resistant to treatment. The retina is part of the central nervous system and shares a common embryonic origin with the brain. Optical coherence tomography (OCT) is an imaging technique for analysing the different layers of the retina. We reviewed studies that examined the retina with OCT in mood disorders.

METHODS

We conducted Pubmed search and additional manual research based on the bibliography in each of selected articles. We found and analysed 11 articles relevant to our subject.

RESULTS

This literature review confirms that it is possible to use OCT to detect neurodegeneration and neuroinflammation in mood disorders. Their impact is thought to depend on the duration and severity of the disease, and whether it is in acute or chronic stage. The differences seen in studies dealing with depression and those looking at bipolar disorder may reflect the particular characteristics of each disorder. A number of OCT parameters can be proposed as biomarkers of active or chronic inflammation and neurodegeneration. Markers of predisposition to an at-risk mental state are also suggested.

LIMITATIONS

The main limitation is selection bias, studies including more varied population would help to confirm and precise these results.

CONCLUSION

OCT is thus a particularly promising tool for evaluating some of the etiopathogenetic mechanisms involved in mood disorders. The combination with other approaches could help to find more specific biomarkers.

Ganglion Cell and Retinal Nerve Fiver Layers Correlated with Time Disease of Bipolar Disorder Using 64 Cell Grid OCT Tool

MATERIALS AND METHODS

Twenty-five eyes of 25 patients with bipolar disorder and 74 eyes of 74 healthy controls underwent retinal measurements of retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) thickness. Measurements were obtained using the Spectralis-OCT device with the new Posterior Pole protocol which assesses the macular area by analyzing retinal thickness in a grid of 64 (8*8) cells.

RESULTS

Significant differences (p < 0.05) in RNFL and GCL thickness were found between BD patients and healthy controls, in parafoveal and perifoveal cells respectively. Significant inverse correlations were found between RNFL and GCL thinning at their thickest location and the duration of bipolar disorder. Several predictive variables were observed with a binary logistic regression for the presence/absence of BD: cell 1.3 RNFL (p = 0.028) and GCL in cells 7.8 (p = 0.012), 2.7 (p = 0.043) and 1.3 (p = 0.047).

CONCLUSION

Posterior Pole OCT protocol is a useful tool to assess changes in the inner retinal layers in bipolar disorder. These observed changes, especially those affecting the GCL, may be associated with disease evolution and may be predictive of the presence of the disease. OCT data could potentially be a useful tool for clinicians to diagnose and monitor BD patients.

The use of optical coherence tomography in the evaluation of patients with bipolar disorder

Bipolar disorder (BD) is a mental disorder characterised by episodes of extremal mood changes. In recent years, some researchers found neurodegeneration in patients with BD using Magnetic Resonance Imaging. Evaluation of the optic nerve and the retinal layers using optical coherence tomography (OCT) has proved to be a useful, non-invasive tool for diagnosis and monitoring of neurodegenerative diseases. Accordingly, a decrease in the retinal nerve fibre layer and the ganglion cell complex measured by OCT was found in patients with BD in different studies, suggesting that BD is a neurodegenerative process in addition to a psychiatric disorder. Therefore, the neuro-ophthalmological evaluation of these patients could be used as a marker for diagnosis of this disease. This work analyses literature on retinal degeneration in bipolar disorder patients, and evaluates the ability of OCT devices in the detection of neuronal degeneration affecting the different retinal layers in these patients, and its possible role in the diagnosis and monitoring of the disease.

Retinal layer abnormalities and their association with clinical and brain measures in psychotic disorders: A preliminary study

Studies utilizing optical coherence tomography (OCT) in psychosis have identified abnormalities in retinal cytoarchitecture. We aim to analyze retinal layer topography in psychosis and its correlation with clinical and imaging parameters. Macular retinal images were obtained via OCT in psychosis probands (n = 25) and healthy controls (HC, n = 15). Clinical, cognitive and structural MRI data were collected from participants. No thinning was noted for the retinal nerve fiber, ganglion cell or inner plexiform layers. We found significant thinning in the right inner temporal, right central, and left inner superior quadrants of the outer nuclear layer (ONL) in probands compared to HC. Thickening of the outer plexiform layer (OPL) was observed in the right inner temporal, left inner superior, and left inner temporal quadrants. The right inner temporal and left inner superior quadrants of both the OPL and ONL showed significant inverse correlations. Retinal pigment epithelium thinning correlated with worse mania symptoms, and thinning in the ONL was associated with worse cognitive function. ONL thinning was also associated with smaller total brain and white matter volume. Our findings suggest that outer retinal layers may provide additional insights into the pathophysiology of psychosis, possibly reflecting synaptic or inflammatory aberrations that lead to retinal pathologies.

Insomnia Might Influence the Thickness of Choroid, Retinal Nerve Fiber and Inner Plexiform Layer

Sleep may play a fundamental role in retinal regulation and the degree of retinal variables. However, no clinical study has investigated optical coherence tomography (OCT) parameters in patients with primary insomnia. All participants were evaluated with the insomnia severity index (ISI) and the Pittsburgh sleep quality index (PSQI). The retinal nerve fiber layer (RNFL), ganglion cell layer (GC), inner plexiform layer (IPL), macula and choroidal (CH) thickness were compared between 52 drug-naïve patients with primary insomnia and 45 age-gender-BMI-smoke status matched healthy controls (HC). The patients with primary insomnia differed from the HC regarding RNFL-Global (p = 0.024) and RNFL-Nasal inferior (p = 0.010); IPL-Temporal (p < 0.001), IPL-Nasal (p < 0.001); CH-Global (p < 0.001), CH-Temporal (p = 0.004), CH-Nasal (p < 0.001), and CH-Fovea (p = 0.019). ISI correlated with RNFL-Global and RNFL-Nasal inferior. The regression analysis revealed that ISI was the significant predictor for the thickness of RNFL- Nasal inferior (p = 0.020), RNFL-Global (p = 0.031), and CH-Nasal (p = 0.035) in patients with primary insomnia. Sleep disorders are seen commonly in patients with psychiatric, including ocular diseases. Adjusting the effect of insomnia can help to clarify the consistency in findings of OCT.

Retinal correlates of psychiatric disorders

Diagnosis and monitoring of psychiatric disorders rely heavily on subjective self-reports of clinical symptoms, which are complicated by the varying consistency of accounts reported by patients with an impaired mental state. Hence, more objective and quantifiable measures have been sought to provide clinicians with more robust methods to evaluate symptomology and track progression of disease in response to treatments. Owing to the shared origins of the retina and the brain, it has been suggested that changes in the retina may correlate with structural and functional changes in the brain. Vast improvements in retinal imaging, namely optical coherence tomography (OCT) and electrodiagnostic technology, have made it possible to investigate the eye at a microscopic level, allowing for the investigation of potential biomarkers in vivo. This review provides a summary of retinal biomarkers associated with schizophrenia, bipolar disorder and major depression, demonstrating how retinal biomarkers may be used to complement existing methods and provide structural markers of pathophysiological mechanisms that underpin brain dysfunction in psychiatric disorders.

A Meta-analysis of Retinal Cytoarchitectural Abnormalities in Schizophrenia and Bipolar Disorder

BACKGROUND

Schizophrenia (SZ) and bipolar disorder (BD) are characterized by reductions in gray matter and white matter. Limitations in brain imaging have led researchers to use optical coherence tomography (OCT) to explore retinal imaging biomarkers of brain pathology. We examine the retinal layers that may be associated with SZ or BD.

METHODS

Articles identified using PubMed, Web of Science, Cochrane Database. Twelve studies met inclusion for acutely/chronically ill patients. We used fixed or random effects meta-analysis for probands (SZ and BD), SZ or BD eyes vs healthy control (HC) eyes. We adjusted for sources of bias, cross-validated results, and report standardized mean differences (SMD). Statistical analysis performed using meta package in R.

RESULTS

Data from 820 proband eyes (SZ = 541, BD = 279) and 904 HC eyes were suitable for meta-analysis. The peripapillary retinal nerve fiber layer (RNFL) showed significant thinning in SZ and BD eyes compared to HC eyes (n = 12, SMD = -0.74, -0.51, -1.06, respectively). RNFL thinning was greatest in the nasal, temporal, and superior regions. The combined peripapillary ganglion cell layer and inner plexiform layer (GCL-IPL) showed significant thinning in SZ and BD eyes compared to HC eyes (n = 4, SMD = -0.39, -0.44, -0.28, respectively). No statistically significant differences were identified in other retinal or choroidal regions. Clinical variables were unrelated to the RNFL or GCL-IPL thickness by meta-regression.

CONCLUSION

The observed retinal layer thinning is consistent with the classic gray- and white-matter atrophy observed on neuroimaging in SZ and BD patients. OCT may be a useful biomarker tool in studying the neurobiology of psychosis.