The value of vision.
BACKGROUND
The value of vision is assumed to be very high. To verify this assumption and to assign resources in medical care accordingly, it is necessary to quantify the value of vision. Although the value of vision is difficult to measure, visual quality of life can be quantified as a surrogate criterion. The measured value gains even more relevance if a comparison can be made between visual quality of life and systemic diseases. Multidisciplinary comparisons are only possible by using utility analysis. Two established methods to measure utility values are the standard gamble method and the time trade-off method. The purpose of this review is to find ophthalmologic utility values, and utility values affected by systemic diseases that correlate to the ophthalmologic ones.


METHODS
A literature search was conducted through PubMed of the National Library of Medicine ( http://www.ncbi.nlm.nih.gov ; date: 06.02.2006). The search terms were: "time trade-off / standard gamble" [text word] and "eye / vision / visual" [text word]; results 24. A report was classified as relevant if visually impaired persons were tested by the time trade-off method or the standard gamble method, or if information was provided on the reliability and validity of these measurements in a group of visually impaired persons. Additional searches were done to find associated publications. A total of 42 publications were found to be of interest.


RESULTS
Results showed that patients, with 20/30-20/50 visual acuity would be willing to pay 19% of their lifetime to get back normal visual acuity. Patients with 20/200-20/400 visual acuity would give up 48% of their lifetime, and blind people would give 60% of their lifetime to regain normal visual acuity. Comparable utility values are seen in patients with AIDS (21%), patients after a stroke who are unable to walk and wash themselves without assistance (46%), and bedridden and incontinent patients following a stroke (66%).


CONCLUSIONS
Patients attach great value to vision. The time trade-off method appears to be an appropriate tool to quantify visual quality of life, and one that can be used to compare utility values of different diseases.
Knauer
Christine
C
Universitäts-Augenklinik, Langenbeckstrasse 1, Gebäude 102, 55131 Mainz, Germany. knauer@augen.klinik.uni-mainz.de
Pfeiffer
Norbert
N
D006801:Humans; D011788:Quality of Life; D012720:Severity of Illness Index; D018434:Sickness Impact Profile; D014785:Vision, Ocular / Q000502:physiology*