[Systemic diagnostic error of senile dementia by cataract-related impairment of information processing?].

Purpose: According to several investigations, late-acquired diagnostically unspecified visual impairments lead to reduced intelligence levels. In cataracts, in particular, we measured reductions in IQ prior to IOL implantation.

Question: Do cataract-related IQ impairments reach the level of senile dementia?

Objective: To examine if cataracts and their removal have a particular relevance in senile dementia.

Methods: The IQ reduction measured in cataract samples in four studies are compared with normal values of dementia. In addition, research of the literature on diagnostic problems.

Results: Compared with the post-surgical score the IQ was much lower before IOL implantation. The difference corresponds to that of dementia with moderate to medium severity. Controls, however, displayed no change of IQ. According to ICD-10 and DSM-IV the cataract patients met the criteria of senile dementia. A review of the literature suggested statistical associations of prevalence of cataract and senile dementia, but did not deal with diagnostic problems.

Conclusions: One component of the psychometrically obtained cognitive impairment in late-acquired cataracts seems to be a methodical artifact. The remaining component, however, cannot be distinguished from that of a "senile dementia" and leads to an increase in severity. In this case, cataract surgery may lower or even abolish the symptoms of dementia within a few weeks which would be of great importance to the patients, their relatives and health insurance.