Most patients with vitreoretinal lymphoma (VRL), a form of diffuse large B-cell lymphoma, will lose their eyesight and eventually die from the disease. Clinical symptoms of vitreous opacities and creamy white subretinal lesions are indicative of lymphoma cell infiltration into the vitreous body and/or subretinal space. Intraocular symptoms can provide hints that point to VRL, but they are not diagnostically definitive and could just as easily be mistaken for uveitis. However, cytological examination of the vitreous often has a low success rate because of the limited quantity and poor quality of tissues and cells in the sample, and histopathological proof of malignant cells on vitreous biopsy is the gold standard for diagnosis of VRL. A proper diagnosis of VRL is now attainable, thanks to recent developments in immunological, molecular, and gene analysis employing intraocular samples. When it comes to treating VRL, intravitreal injections of anti-tumor medicines like methotrexate or rituximab, as well as local treatments like irradiation, can effectively decrease intraocular VRL lesions. It is still debatable, however, whether or not systemic chemotherapy, with or without brain irradiation, is effective in preventing central nervous system involvement. Based on the existing research and some unpublished findings, the following topics will be discussed in this review article: In this article, researchers discuss the most up-to-date methods for examining the eyes, including optical coherence tomography and fundus autofluorescence; the immunological, molecular, and gene expression characterization of intraocular biopsies, with a focus on flow cytometry; polymerase chain reaction-based assays for detecting rearrangements in the immunoglobulin genes; cytokine assays; and gene mutations (MYD88, CD79B).