Visual evoked potentials in diagnostics of optic neuropathy associated with renal failure.

Chronic renal failure is associated with many neurological complications. Due to accumulation of uremic neurotoxins axonal degeneration with its secondary demyelination occurs, which results in development of polineuropathy in 60­100% of patients with chronic renal failure. One of the most severe peripheral neuropathy is optic neuropathy. It is associated with visual deterioration and reduction in quality of life. Symptoms of the optic neuropathy may appear either before or after dialysis therapy. They often worsen after renal transplant, probably due to immunosuppressive regimen. Early diagnostics of the optic neuropathy became possible by using visual evoked potentials (VEP). This reliable, sensitive and noninvasive technique provides a direct measure of subclinical impairment of visual pathways. Among hemodialysed or immunosupressed patients one can observe abnormal VEP parameters - especially prolonged latency of the P100 component, less often fluctuation of its amplitude. These alterations are pronounced even if clinical examination reveals no abnormalities. This review presents a summary of current use of visual evoked potentials in monitoring of patients with chronic renal failure.

The gamma knife in ophthalmology. Part One--Uveal melanoma.

The Gamma Knife was designed by Lars Leksell in the early 1950's. It gave rise to a new discipline of medicine--stereotactic radiosurgery. Primarily dedicated to neurosurgery, the Gamma Knife has become an alternative, widely used surgery technique. According to Elekta's statistics, approximately 60,000 people are treated with Leksell Gamma Knife every year and it is the most extensively studied stereotactic radiosurgery system in the world. The Leksell Gamma Knife can also be used in ophthalmology. The gamma ray beam concentration enables effective treatment of uveal melanoma, choroidal hemangioma, orbital tumors or even choroidal neovascularization. The virtue of Leksell Gamma Knife is its extreme precision, non-invasiveness and the possibility of outpatient treatment, which significantly reduces costs and diminishes post-operative complications. Innovative solutions shorten a single session to a minimum, which is very comfortable and safe for both staff and patients. Advantages and possible side effects of gamma knife radiosurgery are well-documented in the professional literature. The objective of this review is to present the recognized applications of Leksell Gamma Knife in ophthalmology.

The gamma knife in ophthalmology. Part Two--Other ocular diseases.

Gamma Knife was designed by Lars Leksell in the early 1950's. It gave rise to a new discipline of medicine--stereotactic radiosurgery. Main use of Gamma Knife in ophthalmology--discussed in the first part of this paper--is non-invasive treatment of uveal melanoma. Another uses of LGK in ophthalmology cover choroidal hemangioma, orbital tumors and even choroidal neovascularization.

The Effect of Maintenance Treatment with Twice-Daily or Prolonged Once-Daily Tacrolimus Formulation on Visual Evoked Potentials in Stable Kidney Transplant Recipients.

In kidney transplant recipients (KTRs), uraemia-induced central nervous system damage partly subsides, while the long-lasting exposure to tacrolimus may cause pathologic visual evoked potentials (VEP) findings, which have not been investigated yet. Thus, the aim of the present study was to assess the effect of tacrolimus maintenance treatment on bioelectrical function of optic nerves in stable KTRs. Sixty-five stable KTRs were enrolled, including 30 patients treated with twice-daily (Prograf) and 35 patients treated with prolonged once-daily (Advagraf) tacrolimus formulation. In all patients, pattern and flash VEP measurements were performed. Tacrolimus dosing and exposure were also analyzed. Overall, 129 eyes were analyzed. In pattern VEP, both (1°) and (15') latencies of P100 waves were significantly longer, whereas (1°) and (15') amplitudes were lower in the Advagraf group as compared with the Prograf group. Multivariate regression analyses revealed that the use of Advagraf (vs. Prograf) was independently associated with longer (1°) and (15') P100 latencies and lower corresponding amplitudes, whereas log tacrolimus daily dose was only related to amplitudes in a whole study group. In flash VEP, log tacrolimus trough level was associated with negative changes in P2 wave amplitude irrespective of tacrolimus formulation, whereas its association with P2 latency was observed only in the Prograf group. Both the type of tacrolimus formulation and drug exposure influenced the VEP parameters in stable KTRs.