All items demonstrated acceptable fit to the model after collapsing categories to order the response thresholds. The original subscales did not prove valid, and there is some evidence of multidimensionality and poor targeting.

The new Mars Letter Contrast Sensitivity Test shows excellent agreement with the Pelli-Robson test and has similar repeatability. There are subtle differences in the actual contrast levels on different forms of the Mars test, and adjusting for these differences leads to superior repeatability of the Mars test. Thus, the Mars test may be a useful alternative to the Pelli-Robson test offering several advantages, including smaller size, improved durability, and ease of use.

Purpose To investigate abandonment rate of prescribed low vision devices for near tasks and factors associated with abandonment in a U.S. outpatient population. Methods A telephone survey was administered to 88 patients with low vision from four clinical sites approximately one year after examination and prescription of devices. Patients were surveyed on timing and frequency of use and reasons for abandonment of devices. The main outcome measure (abandonment) was defined as patient report of no use of prescribed device in the previous three months. Multivariate logistic regression was used to investigate significant vision and demographic factors related to abandonment. Results Of 119 prescribed devices, 19% (95% CI, 12–26) had not been used within the previous three months. Mean (±SD) better eye visual acuity at examination was 0.61±0.29 logMAR and mean age was 77±17 years. Mean time between device prescription and survey was 11±3 months. Device abandonment was not associated with age (p = 0.863), time since prescription (p = 0.125), visual acuity (p = 0.804), or category of magnification device (spectacle, handheld, stand, or video) (p = 0.412). There was a significant association between documented non-central visual field loss and abandonment of magnification device (p=0.046). Repeat administration of the survey resulted in the same abandonment classification in 15 of 15 patients (100%). Conclusions Abandonment rate was similar for this outpatient population to those previously reported in the U.S. veteran inpatient population and in other countries. Patients with visual field loss may be more likely to abandon prescribed devices.