Oculomics in Schizophrenia Research

Oculomics: Current concepts and evidence

The eye provides novel insights into general health, as well as pathogenesis and development of systemic diseases. In the past decade, growing evidence has demonstrated that the eye's structure and function mirror multiple systemic health conditions, especially in cardiovascular diseases, neurodegenerative disorders, and kidney impairments. This has given rise to the field of oculomics-the application of ophthalmic biomarkers to understand mechanisms, detect and predict disease. The development of this field has been accelerated by three major advances: 1) the availability and widespread clinical adoption of high-resolution and non-invasive ophthalmic imaging ("hardware"); 2) the availability of large studies to interrogate associations ("big data"); 3) the development of novel analytical methods, including artificial intelligence (AI) ("software"). Oculomics offers an opportunity to enhance our understanding of the interplay between the eye and the body, while supporting development of innovative diagnostic, prognostic, and therapeutic tools. These advances have been further accelerated by developments in AI, coupled with large-scale linkage datasets linking ocular imaging data with systemic health data. Oculomics also enables the detection, screening, diagnosis, and monitoring of many systemic health conditions. Furthermore, oculomics with AI allows prediction of the risk of systemic diseases, enabling risk stratification, opening up new avenues for prevention or individualized risk prediction and prevention, facilitating personalized medicine. In this review, we summarise current concepts and evidence in the field of oculomics, highlighting the progress that has been made, remaining challenges, and the opportunities for future research.

Exploring the relationship between the density of the iris color and bipolar disorder: a case-control study, Egypt

BACKGROUND

The eyes serve as a portal to the brain and are highly connected neurologically, making them the only externally visible part of the brain. Moreover, the correlation between the physical attributes of the eye and psychiatric disorders has been increasingly established in recent years. Therefore, this study examined the association between iris color density and bipolar I disorder (BD).

METHODS

In a case-control study, 48 subjects diagnosed with BD are compared to an equal number of healthy controls. A semi-structured interview questionnaire is designed to collect sociodemographic, psychiatric, medical history, and clinical data from all participants. The Group with BD is diagnosed based on clinical assessment by the Consultant/specialist by using a semi-structured clinical interview for DSM 5 Clinician Version (SCID-5-CV) to diagnose BD's current episode and to exclude the other comorbid mental disorders. Additionally, the group with BD is further assessed by The Young Mania Rating Scale (YMRS) and Hamilton Depression Rating Scale (HDRS) to evaluate the severity of manic and depressive symptoms. The iris color of participants in both groups was evaluated using a standardized photographic system for iris imaging.

RESULTS

It showed a statistically significant increase in the percentage of the colored iris in the patients' group compared with the control group, and the presence of a colored iris significantly increases the risk of BD by 2.36 folds. There is no statistically significant difference between iris color and either hospitalization, suicide, Electroconvulsive Therapy (ECT), family history, medical history, duration, or frequency of episodes.

CONCLUSION

Our findings revealed a strong association between iris color and bipolar disorder (BD) but no significant association between iris color and clinical factors such as hospitalization, suicide, electroconvulsive therapy (ECT), family history, medical history, or the duration and frequency of episodes. These results suggest that iris color may serve as a trait marker rather than a state marker in BD, potentially offering a simple and non-invasive indicator of bipolarity.

Retinal structure and its relationship with premorbid, clinical, and cognitive variables in young Spanish patients with early course schizophrenia spectrum disorders

Emerging evidence suggests that retinal structural alterations are present in schizophrenia spectrum disorders (SSD), potentially reflecting broader neurodevelopmental and neurodegenerative processes. This cross-sectional study investigates retinal thickness and its clinical correlations in a sample of early-course SSD patients compared to healthy controls (HCs). One hundred-two eyes from 26 SSD cases and 25 age- and sex-matched HCs were included. Retinal structure was evaluated using Spectral-Domain Optical Coherence Tomography (SD-OCT), focusing on the peripapillary retinal nerve fiber layer (pRNFL), macular volume/thickness, and ganglion cell-inner plexiform layer (GCL+IPL) thickness. Although SSD cases showed increased peripapillary retinal nerve fiber layer (pRNFL) thickness in specific quadrants, most retinal parameters did not differ significantly between groups. Preliminary associations were observed between retinal measures, premorbid adjustment, DUP, and cognitive performance. These findings, while suggesting the potential of retinal imaging as a tool for early detection and monitoring of psychotic disorders, must be interpreted with caution. Further longitudinal and multimodal research is warranted to explore the association between these retinal changes and neuroinflammation, neurodegeneration, and overall brain health in SSD patients.

Retina as a potential biomarker in schizophrenia spectrum disorders: a systematic review and meta-analysis of optical coherence tomography and electroretinography

INTRODUCTION

Abnormal findings on optical coherence tomography (OCT) and electroretinography (ERG) have been reported in participants with schizophrenia spectrum disorders (SSDs). This study aims to reveal the pooled standard mean difference (SMD) in retinal parameters on OCT and ERG among participants with SSDs and healthy controls and their association with demographic characteristics, clinical symptoms, smoking, diabetes mellitus, and hypertension.

METHODS

Using PubMed, Scopus, Web of Science, and PSYNDEX, we searched the literature from inception to March 31, 2023, using specific search terms. This study was registered with PROSPERO (CRD4202235795) and conducted according to PRISMA 2020.

RESULTS

We included 65 studies in the systematic review and 44 in the meta-analysis. Participants with SSDs showed thinning of the peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer- inner plexiform cell layer, and retinal thickness in all other segments of the macula. A meta-analysis of studies that excluded SSD participants with diabetes and hypertension showed no change in results, except for pRNFL inferior and nasal thickness. Furthermore, a significant difference was found in the pooled SMD of pRNFL temporal thickness between the left and right eyes. Meta-regression analysis revealed an association between retinal thinning and duration of illness, positive and negative symptoms. In OCT angiography, no differences were found in the foveal avascular zone and superficial layer foveal vessel density between SSD participants and controls. In flash ERG, the meta-analysis showed reduced amplitude of both a- and b-waves under photopic and scotopic conditions in SSD participants. Furthermore, the latency of photopic a-wave was significantly shorter in SSD participants in comparison with HCs.

DISCUSSION

Considering the prior report of retinal thinning in unaffected first-degree relatives and the results of the meta-analysis, the findings suggest that retinal changes in SSDs have both trait and state aspects. Future longitudinal multimodal retinal imaging studies are needed to clarify the pathophysiological mechanisms of these changes and to clarify their utility in individual patient monitoring efforts.

Collaboration between Psychiatrists and Other Allied Medical Specialists for the Treatment of Delusional Disorders

BACKGROUND

There is increasing evidence that individuals with psychosis are at increased risk for cardiovascular disease, diabetes, metabolic syndrome, and several other medical comorbidities. In delusional disorder (DD), this is particularly so because of the relatively late onset age.

AIMS

The aim of this narrative review is to synthesize the literature on the necessity for medical collaboration between psychiatrists and other specialists.

METHODS

A non-systematic narrative review was carried out of papers addressing referrals and cooperation among specialists in the care of DD patients.

RESULTS

Psychiatrists, the primary care providers for DD patients, depend on neurology to assess cognitive defects and rule out organic sources of delusions. Neurologists rely on psychiatry to help with patient adherence to treatment and the management of psychotropic drug side effects. Psychiatrists require ophthalmology/otolaryngology to treat sensory deficits that often precede delusions; reciprocally, psychiatric consults can help in instances of functional sensory impairment. Close collaboration with dermatologists is essential for treating delusional parasitosis and dysmorphophobia to ensure timely referrals to psychiatry.

CONCLUSIONS

This review offers many other examples from the literature of the extent of overlap among medical specialties in the evaluation and effective treatment of DD. Optimal patient care requires close collaboration among specialties.

Mapping Retinal Abnormalities in Psychosis: Meta-analytical Evidence for Focal Peripapillary and Macular Reductions

BACKGROUND

Several studies have suggested that the retina structure is affected in schizophrenia spectrum disorders (SSD). We aimed to investigate the location and size of the potential differences between patients and healthy controls (HC) in several thickness and volume measures across the retina.

STUDY DESIGN

We included cross-sectional studies comparing peripapillary retinal nerve fiber layer (pRNFL) thickness, macular volume, macular thickness (MT), foveal thickness, ganglion cell and inner plexiform layer thickness (GCL+IPL), cup volume, and cup/disc ratio (C/D) in the right and/or left eyes and/or the pRNFL and MT quadrants between patients with SSD and HC. Search databases were MEDLINE, Web of Science, PsycINFO, Cochrane Central, and medrxiv.org. Risk of bias was assessed with the Newcastle-Ottawa Scale. Standardized mean differences (SMD), subgroup analysis, and meta-regression with several variables were computed using the dmetar package in R. PROSPERO: CRD42021287873.

STUDY RESULTS

Data from 22 reports (942 patients, 742 HC) were included. We found a retinal thinning in pRNFL (-0.30; 95% CI: -0.46, -0.14), macula (-0.37; 95% CI: -0.61, -0.13), and GCL+IPL (-0.33; 95% CI: -0.57, -0.10). The retinal thinning was especially pronounced in the superior and inferior quadrants of the inner ring of the macula. We also observed a decrease of macular volume (-0.44; 95% CI: -0.68, -0.20) and an increase in C/D ratio (0.35; 95% CI: 0.03, 0.67).

CONCLUSIONS

Current evidence demonstrates retinal thinning in SSD, affecting both axonal and cellular structures, specially focused in the inner ring of the macula.

Eyes, the window on psychosis?

Much has been written on the theory that congenital blindness might protect against schizophrenia, but proof remains elusive. It has been suggested that visual ability might be associated with schizophrenia in a bell-shaped distribution, with both lifelong absent and perfect vision being protective. Alternatively, ocular aberrations and schizophrenia may share an aetiology. Any neuronal pathology implicated in schizophrenia could affect the retina, since it is an embryological extension of the brain. The retina is more amenable to direct imaging than other parts of the central nervous system and may give unique insights into schizophrenia-associated neuropathology. It is also possible that psychosis causes visual impairment: people with psychotic illnesses are probably not accessing optical care optimally and have higher levels of risk factors for visual loss.

Study on the Correlation Between Iris Characteristics and Schizophrenia

BACKGROUND

Recently, researchers have conducted many studies on the potential contribution of the retina and other eye structures on schizophrenia. This study aimed to evaluate differences in iris characteristics between patients with schizophrenia and healthy individuals so as to find more easily accessible and easily measurable biomarkers with a view to improving clinical assessments and furthering our understanding of the disease.

METHODS

Overall, 80 patients with schizophrenia and 52 healthy individuals were included in the case group and the control group, respectively. Iris images were collected from all subjects to compare differences in the structure and color of the iris. The Positive and Negative Symptom Scale (PANSS) and the Modified Overt Aggression Scale (MOAS) were used to evaluate the clinical symptoms and characteristics of 45 first-episode untreated schizophrenics, and analyzed correlations between iris characteristics and schizophrenia symptoms.

RESULTS

There were significant differences in iris crypts (P<0.05) and pigment spots (P<0.01) between the case and control group, but no significant difference was found in iris wrinkles (P<0.05). The logistic regression analysis demonstrated that the total iris crypts [odds ratio (OR) 1.166, 95% confidence interval (CI) 1.022-1.330] and total iris pigment spots (OR 1.815, 95% CI 1.186-2.775) increased the risk of suffering from schizophrenia. Furthermore, it was demonstrated that the number of iris crypts was positively associated with the MOAS score (r=0.474, P<0.01). Moreover, the number of the iris pigment spots (r=0.395, P<0.01) and wrinkles (r=0.309, P<0.05) were positively correlated with the subjects' negative symptom scores, respectively.

CONCLUSION

Iris crypts and pigment spots were identified as potential biomarkers for detecting schizophrenia. In patients with first-episode untreated schizophrenia, iris characteristics may help psychiatrists to identify the illness and its severity, and to detect characteristic clinical symptoms.