Vascular risk factors in normal-tension glaucoma and techniques for evaluating ocular blood flow Naczyniowe czynniki ryzyka w jaskrze normalnego ciśnienia i metody pomiaru ocznego przepływu krwi

The most common optic neuropathy is the glaucomatous neuropathy. It involves progressive loss of retinal ganglion cells including their axons and disc damage resulting in visual field loss. The disease, if not treated, can lead to irreversible vision loss. Apart from the age-related macular degeneration glaucoma is the main cause of blindness in civilized countries. Until recently the diagnosis and treatment of glaucoma mainly focused on the detection and reduction of the intraocular pressure, which is found the main risk factor for glaucoma. However, in spite of the normal intraocular pressure some glaucoma patients develop the neuropathy and experience progression of the disease. These patients mostly suffer from the normal-tension glaucoma. According to the current state of knowledge it is believed that one of the leading causes of the optic disk damage in glaucoma is the ischemia of the secondary to elevated intraocular pressure or a disturbance of ocular blood flow. It is considered that the intraocular pressure within statistically normal limits is relatively too high for disk resistance in eyes with normal-tension glaucoma. In these patients the failure of blood circulation in eye usually co-exists with systemic hemodynamic alternations. It is also possible that the disturbances of blood supply to the optic nerve head may cause increased susceptibility of the retinal nerve fibres to the intraocular pressure. The review discusses the mechanisms that (may) affect the regulation of the ocular blood flow and the vascular risk factors that may compromise the systemic and ocular blood flow. The second part of the article summarizes some new visualization techniques for evaluating ocular blood flow.