Impaired dark adaptation in polycythemia. Improvement after treatment.
OBJECTIVE
To determine if dark adaptation is reduced in individuals with polycythemia and if so whether there is any improvement in dark adaptation after treatment.


METHODS
Dark adaptation was recorded monocularly by automatic dark adaptometry in ten consecutive patients with polycythemia before and after treatment. Analogue investigations were performed in 31 healthy control subjects.


RESULTS
Dark adaptation was markedly impaired in the patients as compared with the control subjects. After reduction of the red cell count and normalization of the hematocrit and hemoglobin the dark adaptation was markedly improved. There was no significant change in dark vision in the control subjects negating a confounding learning effect.


CONCLUSIONS
The findings indicate a sustained but reversible neuronal hypofunction secondary to polycythemia. As the rheological abnormality was normalized, dark adaptation was improved, probably secondary to normalized microcirculation within the retina or the brain, or both, possibly with reactivation of formerly inactive neuronal cells.
Havelius
U
U
Department of Ophthalmology, Internal Medicine, University Hospital MAS, University of Lund, Malmö, Sweden. Ulf.Havelius@oftal.mas.lu.se
Berglund
S
S
Falke
P
P
Hindfelt
B
B
Krakau
T
T
D000328:Adult; D000368:Aged; D003623:Dark Adaptation; D003941:Diagnostic Techniques, Ophthalmological; D004906:Erythrocyte Count; D005260:Female; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D018962:Phlebotomy; D011086:Polycythemia / Q000150:complications* / Q000628:therapy; D016896:Treatment Outcome; D014786:Vision Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology
D006454:Hemoglobins