Visual field loss in senile dementia of the Alzheimer's type.

BACKGROUND: Visual performance is impaired in patients with senile dementia of the Alzheimer's type (SDAT). We investigated the visual field topography of these deficits. METHODS: Humphrey automated perimetry (Program 30-2) was used to measure differential luminance sensitivity within the central 60 degrees of the visual field in SDAT patients (n = 61) and in visually and cognitively normal volunteer subjects of similar age (n = 61). Twenty-three SDAT patients were retested 18 months after the original examination. RESULTS: Reliable visual fields (by manufacturer's criteria) were obtained in 72.1% (44/61) of the control subjects and 55.7% (34/61) of the SDAT group. In the SDAT group, differential luminance sensitivity was significantly reduced relative to the control group. Visual sensitivity was reduced throughout the visual field, but deficits were most pronounced in the inferior visual field, where they presented most commonly as arcuate defects. Patients with more severe dementia exhibited greater reductions in visual sensitivity. On follow-up, 14 of 23 SDAT patients exhibited progression of visual field loss, whereas only two of 23 patients exhibited a regression of the visual field loss. CONCLUSIONS: Although automated perimetry requires considerable patient cooperation, many patients with SDAT can produce reliable visual field results. These patients exhibit significant reductions in global sensitivity. Visual field loss in SDAT is most pronounced in the inferonasal and inferotemporal arcuate regions of the visual field but also involves the central field.

Patient compliance--don't count on it!

Patient non-compliance which is a well recognized although poorly understood phenomena that affects patients in all areas of health care. A recent public health study reports that patient non-compliance to medical therapy is responsible for 125,000 deaths each year, hundreds of thousands of hospitalizations and millions of lost workdays. In the contact lens field, patient non-compliance is known to be a causitive factor in the development of contact lens related ocular infections that frequently result in permanently lost vision. This article reviews our current knowledge concerning patient non-compliance and the factors that are felt to be associated with it. It also describes the health belief model and discusses some of the reasons patients are non-compliant. In addition, methods that may be beneficial in improving compliance are discussed.

A nationwide evaluation of the academic performance of male and female optometry students.

The number of women entering optometry has risen steadily over the last two decades. The present study is a nationwide evaluation of the academic performance of male and female optometry students graduating in 1986. The data presented was obtained through the cooperation of 12 of the 15 U.S. schools and colleges of optometry. Factors which were investigated include preoptometry grade point average (GPA), GPA at the end of the first two years of optometry school, GPA for the second two years of optometry (calculated independently from the first two years GPA), Optometry College Admission Test (OCAT) scores, class rank at graduation and awards received at graduation. This analysis revealed very little difference in overall academic performance between male and female optometry students.

Visual field defects in patients with insulin-dependent and noninsulin-dependent diabetes.

Automated perimetry (Humphrey 30-2) was used to quantitate visual field sensitivity in diabetic patients with either little or no retinopathy (n = 38) or mild background diabetic retinopathy (n = 19) and in visually normal controls (n = 40). Foveal thresholds were unaffected in the diabetic patients but significant reductions in visual field sensitivity, measured by both the mean deviation and the pattern standard deviation indices of visual field sensitivity, were observed in the diabetic patients. Subgroup analyses showed that this sensitivity reduction primarily occurred in noninsulin-dependent diabetic patients. Among the diabetic patients, 26.3% of the visual fields were flagged as "probably abnormal." This percentage was greatest among the noninsulin-dependent patients with mild background diabetic retinopathy (72.3%). The sensitivity reductions observed in the noninsulin-dependent patients with mild background diabetic retinopathy tended to be localized in the superior quadrants and correlated with the extent of retinal vascular compromise evident from vitreous fluorophotometry (r = 0.603). These findings imply that in diabetic patients visual field defects (1) often can be detected in patients with at most moderate retinopathy, (2) occur more frequently in noninsulin-dependent patients than in insulin-dependent patients, and (3) may result from subclinical microangiopathy.

A comparison of academic performance of female and male optometry students at the University of Missouri-St. Louis.

The number of women entering optometry has risen steadily over the last 2 decades. The present study compares the academic performance of male and female optometry students in the 1984 through 1986 graduating classes at the University of Missouri-St. Louis School of Optometry. The female students had higher grade point averages upon entering optometry school than their male colleagues although they performed less well than the males on the Optometry College Admissions Test (OCAT) examination. An analysis of optometry grade point averages, class rank and honors received at graduation demonstrated that the women performed at least as well academically as their male counterparts.

Radial keratotomy increases the effects of disability glare: initial results.

Attempts to correct myopia by surgical intervention (radial keratotomy) are increasing, and disability glare is emerging as a common subjective postsurgical complaint. To date, efforts to quantify this complaint have failed. By measuring increment thresholds in the presence of a point-glare source, we have been able to measure large glare effects (up to six times normal) at low background luminance levels.

Investigation of contrast sensitivity following radial keratotomy.

Radial keratotomy is a surgical procedure for the correction of myopia in which the cornea is flattened by partial-thickness radial incisions. While postoperative visual acuity is usually good, measurements of acuity are of only limited value and do not describe visual performance for a variety of spatial frequencies and contrasts. In the present study, the effect of radial keratotomy on the contrast-sensitivity function was examined. Six spatial frequencies were tested (0.5, 1.0, 3.0, 6.0, 11.4, and 22.8 cycles/degree) using the Nicolet CS 2000 with patients wearing corrective lenses. The results revealed that, at least for the conditions tested, radial keratotomy does not produce a statistically significant decline in contrast sensitivity.

Optimal incision diameter in YAG laser capsulotomy.

As YAG laser capsulotomy has become increasingly popular, concern over its side effects has grown. Because side effects appear to be dose related, they are minimized by using the smallest incision consistent with good optical performance of the eye. This paper uses diffraction theory to calculate the minimum incision diameter necessary to allow a patient to achieve optimum acuity.

Age-related alterations in retinal function.

Age-related visual deficits that occur in the absence of recognized visual disease are frequently observed. Many of the optical factors contributing to these deficits have been delineated, but the contributing neurophysiological alterations have not been clearly defined. This investigation examined age-related variations in the retinal and cortical processing of visual information. Pattern-specific retinal potentials (pattern electroretinogram or PERG in this series) and cortical potentials (VECPs) were recorded from nine young visual normals (20-30 years) and nine healthy elderly individuals (70-80 years). All subjects had best corrected visual acuity of 20/30 or better. Checkerboard patterns (7.5-60 min. checks) were modulated in a counterphase mode (2.0 and 7.5 rps). PERGs and VECPs were simultaneously recorded. Significant age-related alterations in waveform amplitude and latency were observed for both biopotentials. The VECP alterations were largely the result of the reduction in retinal illumination associated with senile miosis, but this factor could not account for most of the observed PERG alterations. These results suggest that neurophysiological changes in the retina may underlie some of the visual deficits observed in healthy elderly adults.

Altered pattern evoked retinal and cortical potentials associated with human senescence.

Physiologically healthy elderly individuals often exhibit visual deficits which result from age-related changes in both the transmission characteristics of the ocular media and the functional properties of the neural elements in the visual pathway. Many of the age-related changes in the optical quality of the ocular media have been identified, but the age-dependent variations in visual neurophysiology have not been clearly delineated. This investigation examined age-related alterations in pattern-specific biopotentials generated in the human retina and visual cortex. Counterphasing (2.0 and 7.5 rps) patterns (7.5', 15', 30' and 60' checks) were used to simultaneously monitor pattern-reversal visual evoked potentials (PRVEPs). Young visual normals (20-30 years of age) and healthy elderly observers (70-80 years of age) with visual acuity of 20/30 or better were studied. All data were corrected for the effects of senile miosis on retinal illumination. Significant variations in the waveform characteristics of both biopotentials were noted for the elderly individuals. PRRP amplitude was uniformly reduced for all stimulus conditions. PRVEP amplitude reductions were also noted but were more stimulus specific than the PRRP amplitude reductions. No significant PRVEP or PRRP latency changes were observed. These results suggest that alterations in the physiological properties of neural elements in both the retina and visual cortex are associated with normal aging.

Adverse consequences of altering the Farnsworth-Munsell 100-Hue test.

Modifications of the Farnsworth-Munsell 100-Hue test (e.g., selection of new fixed-reference caps from within the test) have been proposed, with little or no theoretical justification or experimental verification. Predictions based on theoretical considerations of the underlying nature of the test and verified by experimental measurements on subjects with known color defects demonstrate that (1) modification can destroy the very nature of the test; (2) modification can alter axis determination and therefore, potentially, the diagnosis; (3) the resulting test scores cannot be compared reliably to established norms; and (4) accurate predictions of test performance can be made from theoretical considerations.

Power spectral analysis of visual evoked potentials in multiple sclerosis.

Power spectral analysis (PSA) was performed on the visual evoked potentials (VEPs) to counterphased checkerboard stimuli from 98 eyes in 49 patients with multiple sclerosis (MS) and 54 eyes of 27 normal volunteers. Attenuation of high frequency components of the transient visual evoked potential was found in 53% of MS patients and 4% of controls. Loss of high frequency components was poorly correlated with prolonged latency (r = 0.346). The consideration of both PSA and latency of the VEP increased the percentage of MS patients exhibiting visual pathway conduction abnormalities from 61% to 86%. The use of PSA in the diagnosis of MS is useful in increasing detection especially in cases where deformed waveforms preclude a reliable estimation of latency.

LASCER Bode plots for normal, amblyopic, and stereoanomalous observers.

Indices of laterality, interocular response latency difference, and binocular summation derived from Bode plots (amplitude-versus-temporal frequency and phase lag-versus-temporal frequency) of cortical responses evoked by laser speckle (LASCER) are correlated with common tests used in clinical refraction. We evaluated eight normal observers and eleven observers with histories of amblyopia and/or stereoanomalies. We find that: (1) LASCER amplitude is reduced in the amblyopic eyes relative to the unaffected fellow eyes, (2) LASCER response latency is increased in the amblyopic eyes relative to the unaffected fellow eyes, and (3) binocular LASCER summation is reduced in stereoanomalous observers. The phenomenal appearance of laser speckle is different for amblyopic eyes than unaffected fellow eyes. Neural disturbances in pattern perception may account for these results.