Subjective and objective symptoms following intraocular lymphoma could lead to a misdiagnosing at the beginning of disease what is the cause for delay of an effective treatment. The most common manifestation of lymphoma is an inflammatory disease affecting uvea. A multidisciplinary approach to the diagnosis is required. Suspicion based on the ophthalmologic examinations has to be verified by histology. We present a case report of a 78-year-old patient examined at our clinic with progressive loss of vision on the left eye in 6 months, suspected of retinal detachment. Objectively the visual acuity was counting fingers in front of the left eye. Intraocular pressure changed from normotensive into hypertensive values during regular examinations. We realised imaging exams, ultrasonography and magnetic resonance, which proved intraocular tumour with retrobulbar infiltration and retinal detachment. The patient was indicated for enucleation which enabled assignment of a histologic type of intraocular lymphoma B-Non-Hodgkin lymphoma from marginal zone B-cells. We sent the patient to a haematologist-oncologist for managing of the following treatment and we prescribed individual prosthesis to the patient after the enucleation. The patient remains in observation, no surgical treatment, chemotherapy or radiotherapy have been used for 23 months after the enucleation. The enucleation was both a diagnostic and treatment modality.