Disturbances of functional parameters of the visual system in conservatively treated and haemodialysed patients with non-diabetic chronic kidney disease

Aim
Chronic kidney disease is becoming a serious problem of public health also because in its initial stage, the disease is latent. Haemodialysotherapy may contribute to negative biochemical processes and also may affect the function of the visual system. The aim of the study was to evaluate changes in functional parameters of the visual system in patients with severe and end-stage chronic kidney disease.

Material and methods
Depending on the value of estimated glomerular filtration rate (eGFR) and applied therapy, the studied individuals were divided into three groups. Group I: patients with chronic renal failure on haemodialysis (chronic kidney disease, stage 5); Group II: patients with markedly decreased estimated glomerular filtration rate (chronic kidney disease, stage 4); Group III: people with normal estimated glomerular filtration rate. Distance and near best-corrected visual acuity, contrast sensitivity, colour vision, carboxymethyllysine (CML) concentration, lens and macula were examined.

Results
Mean best-corrected distance visual acuity were statistically different (p = 0.000815) in Group I and III. Mean near visual acuity was similar in all groups (p = 0.0886). Contrast sensitivity differed between Group II and III (p = 0.004895). Colour vision differed statistically between study groups (p = 0.027). Carboxymethyllysine concentration differed significantly between Groups I and III (p = 0.001450) and between Group II and III (p = 0.001325).

Conclusions
Chronic kidney disease considerably affects the functional state of the visual system. Patients with chronic kidney disease demonstrate impaired contrast sensitivity and colour vision disturbances. Chronic haemodialysis may improve colour vision and, to some extent, parameters regarding contrast sensitivity.