Visual function and mobility after multifocal versus monofocal intraocular lens implantation.

Clinical relevance: Mobility and fall risk may be important considerations in choosing between intraocular lenses.Background: Fall risk in older adults increases when wearing multifocal spectacles, but little is known about mobility among individuals with different types of intraocular lenses. This study compared visual function, fall risk and balance control following bilateral implantation of monofocal or multifocal intraocular lenses.Methods: This was a non-randomised, cross-sectional study involving adults with bilateral intraocular lenses. Participants completed questionnaires concerning physical functioning, fall history and balance-related confidence. Binocular visual acuity, contrast sensitivity (Pelli-Robson chart and computerized testing), depth perception and glare sensitivity were assessed. Physical performance measures included the Sensory Organization Test, preferred gait speed, Dynamic Gait Index and wayfinding in a virtual environment.Results: Fifteen participants (mean ± standard deviation, 67.1 ± 6.8 years) had monofocal intraocular lenses and 14 participants (68.1 ± 6.1 years) had multifocal intraocular lenses. Contrast sensitivity in the monofocal group was significantly better than that in the multifocal group (p = 0.02) at intermediate and high spatial frequencies. Contrast sensitivity of the monofocal group also was less affected by glare than the contrast sensitivity of the multifocal group, at an intermediate spatial frequency (p = 0.02). However, the multifocal group had significantly better Dynamic Gait Index scores (p = 0.04), even after controlling for perceived physical function.Conclusions: The participants with monofocal intraocular lenses generally had better contrast sensitivity than did those with multifocal intraocular lenses. However, the scores on a mobility test that is associated with fall risk were worse for those with monofocal lenses.

Age effects on visual-perceptual processing and confrontation naming.

The impact of age-related changes in visual-perceptual processing on naming ability has not been reported. The present study investigated the effects of 6 levels of spatial frequency and 6 levels of contrast on accuracy and latency to name objects in 14 young and 13 older neurologically normal adults with intact lexical-semantic functioning. Spatial frequency and contrast manipulations were made independently. Consistent with the hypotheses, variations in these two visual parameters impact naming ability in young and older subjects differently. The results from the spatial frequency-manipulations revealed that, in general, young vs. older subjects are faster and more accurate to name. However, this age-related difference is dependent on the spatial frequency on the image; differences were only seen for images presented at low (e.g., 0.25-1 c/deg) or high (e.g., 8-16 c/deg) spatial frequencies. Contrary to predictions, the results from the contrast manipulations revealed that overall older vs. young adults are more accurate to name. Again, however, differences were only seen for images presented at the lower levels of contrast (i.e., 1.25%). Both age groups had shorter latencies on the second exposure of the contrast-manipulated images, but this possible advantage of exposure was not seen for spatial frequency. Category analyses conducted on the data from this study indicate that older vs. young adults exhibit a stronger nonliving-object advantage for naming spatial frequency-manipulated images. Moreover, the findings suggest that bottom-up visual-perceptual variables integrate with top-down category information in different ways. Potential implications on the aging and naming (and recognition) literature are discussed.

Scotopic sensitivity in schizophrenia.

Among participants with schizophrenia there is evidence for early-stage visual processing deficits, which may arise in the rod pathways. Input to the earliest level of this pathway, however, has not been tested in this population. It has been widely hypothesized that schizophrenia participants have magnocellular deficits that occur at the pre-cortical level. To address this hypothesis, we studied absolute scotopic (dark-adapted) sensitivity in fifteen schizophrenia and fifteen matched control participants. Scotopic thresholds were assessed using a 1.85-deg, 510-nm circular test stimulus located at 10 degrees eccentricity in the left visual field and presented in Maxwellian-view. Thresholds were obtained using a two-alternative forced-choice paradigm (an average of 200 trials per participant was obtained). Threshold estimates were derived using probit analysis. In this procedure the transformed binomial data (the inverse of the normal probability integral) is fit with a weighted linear regression. Noise was defined as the average deviation from this line. Lens optical density was also assessed by comparing absolute scotopic thresholds to the extinction spectrum of rhodopsin. Scotopic thresholds and lens density values of the two groups were evaluated using independent samples t-tests. The scotopic thresholds, and associated noise, did not differ between the schizophrenia and control participants. Lens density was also nearly identical between groups. These results suggest that magnocellular deficits in schizophrenia may not be due to problems at the level of the rods but are more likely to occur later in the visual pathway.

Critical flicker fusion frequency: relation to resting systolic blood pressure.

OBJECTIVE: Past studies have shown that a number of factors, both acute and chronic, influence individual differences in critical flicker fusion frequency (CFF). In this study, we assessed whether CFF co-varied with resting systolic blood pressure (SBP). METHODS: SBP and CFF were assessed in one session in 221 subjects (mean age, 19.6 +/- 2.5 years), and SBP and CFF were assessed over 10 sessions in 12 subjects. CFF values were determined psychophysically using a 570 nm circular 1 degrees test field centrally fixated. Blood pressure was determined with an automated sphygmomanometer. RESULTS: There was a significant (p < 0.0002) positive relation between CFF and SBP for the larger sample (n = 221). Significant within-subject relations were found for 6 of the 12 subjects tested repeatedly. CONCLUSIONS: The combination of results strongly suggests that CFF and resting SBP are positively related.