This study investigates the genetic connections between retinal and brain structures using multimodal retinal and brain imaging data. The retina, an extension of the brain, forms physiological connections with the visual cortex. Retinal imaging biomarkers were found to be genetically linked to brain structure and function measures, particularly in the primary visual cortex and visual pathways. Genetic overlaps were identified between retinal imaging traits and brain MRI traits in 65 genomic regions, with 18 showing genetic overlap with brain MRI traits. Mendelian randomization suggested bidirectional genetic causal links between retinal structures and neurological and neuropsychiatric disorders, such as Alzheimer's disease. The study revealed the genetic basis for eye-brain connections, suggesting that retinal images can help uncover genetic risk factors for brain disorders and disease-related changes in intracranial structure and function. The retina, a critical component of the central nervous system, plays a key role in the visual pathway. It connects synaptically to the visual cortex through the optic nerve, thalamus, and optic radiations. The retina and brain share anatomical, physiological, and embryological similarities. Retinal imaging biomarkers were found to be associated with various brain disorders, including Alzheimer's disease, Parkinson's disease, stroke, and schizophrenia. Retinal neurodegeneration is strongly associated with amyloid β burdens in Alzheimer's disease and has been widely studied as an easily accessible biomarker for identifying individuals at high risk of developing Alzheimer's disease. Retinal imaging traits, such as retinal thickness and vertical cup-to-disc ratio, were found to be genetically linked to brain structure and function measures. These traits were associated with brain volumes, cortical thickness, and diffusion tensor imaging (DTI) parameters. The study used the UK Biobank dataset to analyze the genetic relationships between retinal and brain imaging traits. A total of 156 retinal imaging traits were examined, including 46 derived from OCT images and 110 from fundus photographs. These traits were found to be genetically linked to 458 brain MRI traits, including 101 regional brain volumes, 63 cortical thickness traits, 110 DTI parameters, and 92 functional connectivity and activity traits. The study identified significant genetic correlations between retinal imaging traits and brain MRI traits, with many associations involving the primary visual cortex and visual pathways. The results suggest that retinal imaging can serve as a valuable tool for uncovering genetic risk factors for brain disorders and disease-related changes in intracranial structure and function. The study also found genetic overlaps between retinal imaging traits and brain-related complex traits and diseases, including Alzheimer's disease, Parkinson's disease, and schizophrenia. These findings highlight the potential of retinal imaging as a biomarker for brain disorders and provide insights into the genetic basis of eye-brain connections.This study investigates the genetic connections between retinal and brain structures using multimodal retinal and brain imaging data. The retina, an extension of the brain, forms physiological connections with the visual cortex. Retinal imaging biomarkers were found to be genetically linked to brain structure and function measures, particularly in the primary visual cortex and visual pathways. Genetic overlaps were identified between retinal imaging traits and brain MRI traits in 65 genomic regions, with 18 showing genetic overlap with brain MRI traits. Mendelian randomization suggested bidirectional genetic causal links between retinal structures and neurological and neuropsychiatric disorders, such as Alzheimer's disease. The study revealed the genetic basis for eye-brain connections, suggesting that retinal images can help uncover genetic risk factors for brain disorders and disease-related changes in intracranial structure and function. The retina, a critical component of the central nervous system, plays a key role in the visual pathway. It connects synaptically to the visual cortex through the optic nerve, thalamus, and optic radiations. The retina and brain share anatomical, physiological, and embryological similarities. Retinal imaging biomarkers were found to be associated with various brain disorders, including Alzheimer's disease, Parkinson's disease, stroke, and schizophrenia. Retinal neurodegeneration is strongly associated with amyloid β burdens in Alzheimer's disease and has been widely studied as an easily accessible biomarker for identifying individuals at high risk of developing Alzheimer's disease. Retinal imaging traits, such as retinal thickness and vertical cup-to-disc ratio, were found to be genetically linked to brain structure and function measures. These traits were associated with brain volumes, cortical thickness, and diffusion tensor imaging (DTI) parameters. The study used the UK Biobank dataset to analyze the genetic relationships between retinal and brain imaging traits. A total of 156 retinal imaging traits were examined, including 46 derived from OCT images and 110 from fundus photographs. These traits were found to be genetically linked to 458 brain MRI traits, including 101 regional brain volumes, 63 cortical thickness traits, 110 DTI parameters, and 92 functional connectivity and activity traits. The study identified significant genetic correlations between retinal imaging traits and brain MRI traits, with many associations involving the primary visual cortex and visual pathways. The results suggest that retinal imaging can serve as a valuable tool for uncovering genetic risk factors for brain disorders and disease-related changes in intracranial structure and function. The study also found genetic overlaps between retinal imaging traits and brain-related complex traits and diseases, including Alzheimer's disease, Parkinson's disease, and schizophrenia. These findings highlight the potential of retinal imaging as a biomarker for brain disorders and provide insights into the genetic basis of eye-brain connections.