Puumala virus infection (nephropathia epidemica) is a disease in the group of hemorrhagic fevers with renal syndrome causing ocular manifestations, e.g. transient myopia and changes in intraocular pressure.Comprehensive and repeated ophthalmic examinations of a previously healthy 35-year-old woman with acute Puumala virus infection were performed. Special attention was paid to ophthalmic A-scan ultrasound measurements and simultaneous blood chemistry tests.The ocular manifestations of this patient's illness included transient myopia, low intraocular pressure, conjunctival hemorrhages and changes of intraocular dimensions. There was forward movement of the anterior diaphragm and thickening of the crystalline lens, which occurred simultaneously with prominent fluctuations in the electrolyte balance, especially potassium.The observed changes in intraocular dimensions may have been caused by simultaneous fluctuations in electrolyte and osmotic balance, which could explain the myopic shift. The symmetry of the ocular measurements implied a systemic infection as the underlying reason for the ophthalmic symptoms and signs.