Acuity Deficits Research Articles

Olfactory acuity deficits for the odour of schizophrenia in chronic and first-episode patients

Olfactory acuity deficits for the odour of schizophrenia in chronic and first-episode patients

Lateralized olfactory acuity deficits and olfactory misidentification in schizophrenia

Lateralized olfactory acuity deficits and olfactory misidentification in schizophrenia

Motion parallax: effects of blur, contrast, and field size in normal and low vision.

Can people with different forms of low vision use motion parallax to improve depth judgments? We used a staircase method to compare depth thresholds using motion parallax and static viewing. We tested eighteen normal-vision subjects with a range of simulated deficits in acuity, contrast sensitivity, and simulated peripheral-field loss, and ten low-vision subjects with a wide range of acuity, contrast sensitivity, and field loss. Subjects viewed three vertical cylinders monocularly and indicated which one was at a different depth from the other two. For motion-parallax trials, observers moved their heads (in a viewing assembly on rollers) from side to side over a range of 6-12 cm. For static trials, the viewing assembly was fixed in place. Normal-vision subjects' depth thresholds with motion parallax were significantly smaller than those with static viewing by an average factor of 1.95 (p < 0.05) across all levels of acuity and contrast. For low-vision observers, the depth thresholds exhibited large individual differences; however, the motion-parallax thresholds were smaller than the static thresholds by an average factor of 2.05 (p < 0.01). These findings indicate that motion parallax can provide useful depth information for people with low vision.

Grating acuity and visual-field development in children with intraventricular hemorrhage.

Visual development was studied in 171 preterm children who had intraventricular hemorrhage (IVH) and in 73 healthy preterm (HPT) children who did not develop IVH. Binocular grating acuity was assessed at age 1 month; monocular grating acuity and binocular visual-field extent were assessed at 4, 8, 12, 17, 24, 30, 36, and 48 months; and monocular H, O, T, V letter recognition acuity was tested at 36 and 48 months. A significantly greater proportion of IVH subjects than HPT subjects had ocular abnormalities. IVH subjects had significantly poorer grating acuity than HPT subjects at 1, 4, 8, 36, and 48 months, poorer recognition acuity than HPT subjects at 36 and 48 months, and smaller average field extent than HPT subjects at 4, 12, and 17 months. Acuity deficits were not related to grade of IVH or to the presence of periventricular leukomalacia, but may have been associated with the presence of ocular abnormalities or cerebral palsy in some IVH subjects.

A comparison of tests to determine acuity deficits in children with amblyopia

SummaryThe usefulness of the Cardiff Acuity Test in the detection of amblyopia was evaluated. Visual function was measured using pattern visual evoked potentials (VEPs), the Cardiff test, and the Bailey‐Lovie Chart in 21 visually normal children and 12 children with amblyopia. The Cardiff test gave higher scores than the Bailey‐Lovie test. The Cardiff test identified five of the 12 children who were classified as amblyopic by the Bailey‐Lovie test. Interocular VEP latency differences identified eight of the 12 children with amblyopia; interocular VEP amplitudes correctly identified nine. We suggest that the challenging Bailey‐Lovie test be used for older children who know their letters well. If the Bailey‐Lovie test cannot be used, VEPs give the most accurate assessment of interocular differences. The Cardiff test holds a bored child's attention and allows the examiner to obtain a useful measure of visual acuity, but it cannot detect mild amounts of amblyopia.

A comparison of tests to determine acuity deficits in children with amblyopia

The usefulness of the Cardiff Acuity Test in the detection of amblyopia was evaluated. Visual function was measured using pattern visual evoked potentials (VEPs), the Cardiff test, and the Bailey-Lovie Chart in 21 visually normal children and 12 children with amblyopia. The Cardiff test gave higher scores than the Bailey-Lovie test. The Cardiff test identified five of the 12 children who were classified as amblyopic by the Bailey-Lovie test. Interocular VEP latency differences identified eight of the 12 children with amblyopia; interocular VEP amplitudes correctly identified nine. We suggest that the challenging Bailey-Lovie test be used for older children who know their letters well. If the Bailey-Lovie test cannot be used, VEPs give the most accurate assessment of interocular differences. The Cardiff test holds a bored child's attention and allows the examiner to obtain a useful measure of visual acuity, but it cannot detect mild amounts of amblyopia.

Depressive Styles and Social Acuity

Social acuity has been identified as an important skill in promoting positive interpersonal and psychological functioning. Because research examining the accuracy of depressives' social perceptions has revealed inconsistent findings, the authors proposed that it may be helpful to consider the dimension of personality. Specifically, they examined whether dependency and self-criticism, 2 personality types that have been linked with depression, were related to social acuity. They hypothesized that whereas self-critical persons would show deficits in social acuity, dependent persons would be more skilled in this area. Ninety university students completed 2 measures of social acuity; the Interpersonal Perception Task and a task requiring subjects to estimate how they were perceived by peers on 10 trait dimensions. Results showed that self-critical persons were significantly less accurate on both tasks, even when controlling for depressive symptomatology. Dependency was unrelated to either measure of social acuity. Results support previous studies showing serious impairments in the interpersonal functioning of self-critical persons and point to distinct interpersonal correlates of dependency and self-criticism.

Color and luminance vision in human amblyopia: Shifts in isoluminance, contrast sensitivity losses, and positional deficits

The deficits for contrast detection and positional accuracy were compared for chromatic and luminance mechanisms within a group of strabismic and anisometropic amblyopes. We found that the isoluminant point was shifted towards red in the amblyopic compared to the fellow normal eye. This was not accounted for by eccentric fixation by the amblyopic eye. Contrast sensitivity deficits were similar for luminance and color stimuli in normal and amblyopic visual systems. In the majority of our amblyopic subjects, however, the deficits in positional acuity were greater for the chromatic than the luminance stimuli.

Velocity Criteria for ???Foveation Periods??? Determined from Image Motions Simulating Congenital Nystagmus

Foveation periods are brief intervals in the congenital nystagmus (CN) waveform when the image is on or near the fovea and eye velocity is relatively slow. The purpose of this study was to determine how visual acuity depends on image velocity for foveation periods of different durations. Visual acuity was measured using high-contrast, single Landolt Cs in four normal observers during image motion simulating that in jerk nystagmus. The "simulated foveation periods" ranged from 20 to 100 ms in duration and 0 to 16 degrees approximately in velocity. The "critical velocity" was defined as the velocity during simulated foveation periods that produced a just-noticeable worsening of acuity (0.05 and 0.1 logMAR) from that in the zero-velocity condition. Critical velocity increased from approximately 3 degrees approximately for simulated foveation durations between 100 and 40 ms to approximately 5 degrees approximately for a simulated foveation duration of 20 ms. Critical velocities increased further when the targets were presented peripherally or with optical blur, to introduce an additional acuity loss. A consequence of these findings is that less recovery of acuity should be expected when retinal image motion is reduced in individuals with CN if a sensory acuity deficit coexists.

Vernier acuity in amblyopic and nonamblyopic children.

We measured vernier acuity in normal and amblyopic children using a procedure that resembles a video game and is suitable for testing most children older than 4 years old. In this procedure, subjects align bars using two keys of a computer keypad. Following binocular practice trials, monocular vernier acuity was measured in 38 control children, 5 to 15 years old, and in 18 children with histories of amblyopia. Vernier acuity was defined as the standard deviation of adjusted position across a block of six trials. Vernier acuity improved as a function of age in the control subjects, indicating developmental improvement. Amblyopic subjects with strabismus (n = 5) and with both anisometropia and strabismus (n = 8) showed markedly impaired vernier acuity in their amblyopic eyes, with vernier acuitys four to five times larger than those of age-matched controls. However, the amblyopic subjects who were anisometropic (n = 5), without any history of strabismus, were not significantly different from control subjects in either eye. Testing with bars and gratings gave similar results. To our knowledge, this is the first study showing that vernier acuity deficits seen in adult amblyopes are also seen in child amblyopes.

Grating Visual Acuity in Eyes With Retinal Residua of Retinopathy of Prematurity

To compare grating visual acuity of eyes with varying severity of retinal residua of retinopathy of prematurity to grating visual acuity of eyes that did not have acute-phase retinopathy of prematurity, showed no ocular abnormalities on follow-up, and were from patients who passed neurodevelopmental screening questions. Monocular grating visual acuity was measured by means of the Teller acuity card procedure when children reached 1, 2, 3 1/2, and 4 1/2 years of age. A total of 1398 children with birth weights less than 1251 g whose acute-phase retinopathy of prematurity was documented as part of the Multicenter Cryotherapy for Retinopathy of Prematurity Study and who participated in follow-up visual acuity testing. Eyes with no or mild residua of retinopathy of prematurity showed a mean visual acuity similar to that of the comparison group. Eyes in a subgroup with abnormally straightened temporal retinal vessels showed a mean visual acuity approximately 1 octave below that of the comparison group. Mean visual acuity scores from eyes with macular heterotopia ranged from 1 octave (at 1 year) to more than 2 octaves (at 4 1/2 years) below the mean visual acuity of the comparison group. Mean visual acuity scores for the few eyes in the retinal fold or partial detachment group that had quantifiable visual acuity were well below the means for the comparison group. Acute-phase retinopathy of prematurity that regresses without retinal residua produces no deficit in grating visual acuity between 1 and 4 1/2 years of age. In contrast, eyes with macular heterotopia show a visual acuity deficit, and the deficit is greater at older than at younger ages. Eyes with retinal fold or partial detachment that have measurable visual acuity show large visual acuity deficits at all ages.

The course of myopia in children with mild retinopathy of prematurity

The courses of spherical equivalent in patients (n = 62) who had mild, non-cicatricial retinopathy of prematurity (ROP), and in those without a history of ROP (n = 25) were modeled as a linear function of age; an exponential model was also considered. A few (n = 5) without ROP have abnormal courses characterized by hyperopia in early infancy; none have poor acuity. Although the majority of patients with ROP have courses indistinguishable from those of term born controls, 27 (43.5%) have abnormal courses, most of which are toward myopia. Optotype acuities were significantly poorer among the ROP patients with abnormal than normal refractive courses. Thus abnormal refractive development and acuity deficits are associated in eyes that have had mild ROP.

GRATING ACUITY AND VISUAL FIELD DEVELOPMENT IN INFANTS FOLLOWING PERINATAL ASPHYXIA

Grating acuity and visual fields were assessed in 66 children who had had perinatal asphyxia (ASPH). Also tested were 41 healthy preterm children (H-PT). Subjects were tested at birth to one month, and four, nine, 12, 17, 24, 30 and 36 months corrected age. The mean acuity scores of the ASPH group were lower than those of the H-PT group at most test ages, and significantly so at 30 and 36 months. The mean visual field size of the infants in the ASPH group was significantly smaller than that of the H-PT group at nine, 12, 30 and 36 months. No significant effects were found for preterm vs term birth, gestational age at birth, degree of asphyxia and presence of strabismus. However, central nervous system abnormalities (intraventricular haemorrhage and periventricular leukomalacia) were related to deficits in acuity and visual field size.

Development of grating acuity, letter acuity, and visual fields in small-for-gestational-age preterm infants

Visual acuity and visual field development were assessed longitudinally in 21 preterm children who were born small-for-gestational-age (SGA) and in 51 preterm children who were appropriate-for-gestational-age (AGA). Grating acuity was tested binocularly at 0–1 month and monocularly at 4, 9, 12, 18, 24, 30, 36 and 48 months corrected age, using Teller acuity cards. Visual fields were measured binocularly using kinetic perimetry at the same ages. Recognition (letter) acuity testing was attempted using the crowded HOTV test in all subjects who came in for testing at 36 and 48 months. Children in the SGA group were matched to children in the AGA group by gestational age (± 3 weeks) and type of perinatal medical complications. There were no significant differences in grating acuity or binocular visual field size between the SGA and AGA groups. 78% of acuity scores for individual SGA-AGA pairs fell within one octave of perfect agreement. Binocular visual field size for each SGA-AGA pair also showed good agreement. Fewer SGA than AGA subjects were able to perform recognition acuity testing, and those SGA subjects who were able to perform the test, showed consistently poorer recognition acuity than their AGA counterparts. Thus, being SGA does not pose an additional risk for the development of grating acuity or binocular visual field size over the first 4 years of life in preterm children. SGA preterm children may be at risk, however, for acuity deficits when acuity is measured with the more complex targets and the greater test distance used to measure recognition acuity.

Effects of posterior segment disorders on oscillatory displacement thresholds, and on acuities as measured using the potential acuity meter and laser interferometer.

Oscillatory displacement thresholds (ODTs) were measured in 67 subjects with clear ocular media, but known posterior segment disorders. The ability of these thresholds to assess reduced visual function, as quantified by visual acuity deficits, was compared with that of the Potential Acuity Meter (PAM) and the Rodenstock Retinometer (RR). ODTs were found to be sensitive to acuity deficits which were retinal/neural in origin. Despite the fact that interferometric acuities are, unlike ODTs, a measure of resolution, the RR proved no more accurate in assessing the level of letter acuity which existed than did ODT measurement. As would be expected, the PAM provided for the most accurate means of assessing non-optical visual acuity deficits. However, the PAM proved to be less useful in eyes with: very poor levels of acuity, and certain anomalous conditions. The results have implications for the relative ability of each of the three tests to identify reduced visual function behind cataract.

Visual dysfunction in the spontaneously hypertensive rat

We report two forms of visual defect in the spontaneously hypertensive rat (SHR) compared to its normotensive control strain (WKY). Ten-month-old male SHR and WKY were tested for intensity discrimination ability using a Y-maze and food reward. The SHR took more trials in the acquisition phase of the task using white light. In the test phase, in which the white light intensity difference was reduced, there was no significant difference in performance between SHR and WKY. Also, there was no significant difference between the strains when red light was used. The defect in SHR occurred in the blue range of the spectrum. Using blue light, the performance of SHR declined significantly at an intensity difference of 1.15 lux, whereas the performance of WKY did not decline significantly until the difference reached 0.01 lux. The defect in SHR for intensity discrimination was not related to cataract formation, but we detected a strain difference in the nuclei of the photoreceptor cells. Thus, this visual dysfunction may involve the rod photoreceptors. Further testing revealed a deficit in visual acuity in SHR aged 40–66 days, prior to the development of hypertension. Thus, the visual dysfunction of SHR is not secondary to their development of hypertension, but rather a discrete characteristic of the strain.

The aged mouse as a model of cognitive decline with special emphasis on studies in NMRI mice

The use of the aged mouse as an integrated model of age-related cognitive decline is reviewed, with special emphasis on experiments covering the life span of NMRI mice, using different age-groups ranging from 3 through to 22 months. Age-related changes in the sensorimotor profile, spontaneous behaviour and performance in learning and memory tasks are considered. The data provide evidence for cognitive impairment and decreases in spontaneous activity and exploration from middle age onwards. Chronologically, this age depends on the longevity of the strain selected; in NMRI mice, middle age corresponds to 11–12 months. Complex learning tasks, such as the Morris water maze for spatial learning, appear to be the most sensitive to age-related changes, as are tests requiring prolonged retention of acquired information, for example, using passive avoidance. Cued and simple discrimination learning are only impaired in the oldest animals. Age-related changes in non-cognitive variables, including sensorimotor capacity, pain sensitivity, emotionality, or locomotor activity, do not account for the learning impairments, although deficits in visual acuity cannot be excluded in the very old animals. Detailed analysis of the individual data for middle aged and old mice, using discriminant and correlation studies highlight a marked heterogeneity between animals of any given chronological age. Furthermore, individual aged mice do not exhibit similar degrees of impairment across all the behavioural variables, showing that aging is not a uniform process. The possible relationship between age-related behavioural decline and neurochemical changes is an area as yet unexplored apart from a few isolated investigations, including a study on ChAT and AChE in NMRI mice. The studies in the NMRI mice illustrate the value of investigating the full age-range to detect an age group which shows cognitive decline dissociable from physical or emotional changes and which is representative of the population as a whole.

Contrast sensitivity and vernier acuity in amblyopic monkeys

Human psychophysical studies suggest that strabismic and anisometropic amblyopes may have characteristically different patterns of visual loss. In particular, anisometropic amblyopes often show deficits on spatial localization tasks that scale with their spatial resolution losses, whereas strabismic amblyopes can show localization deficits that are large relative to their losses in spatial resolution. We have compared the performance of non-human primates with experimentally-induced anisometropic and strabismic amblyopia on contrast detection and vernier acuity tasks. The performance of both groups of animals was fundamentally similar: both strabismic and anisometropic monkeys showed deficits in spatial localization that were large relative to their resolution losses, although the animals with the most disproportionate losses were strabismic. We investigated the extent to which contrast sensitivity losses accounted for the vernier acuity deficits. The results showed that, in most cases of either strabismic or anisometropic amblyopia, when the vernier stimuli for each eye were equated in terms of effective contrast, the extent of the vernier acuity deficit was reduced to approximately the extent of the spatial resolution deficit. In two cases, both of strabismic amblyopia, we found that equating the stimuli in this way was not sufficient to make the deficits equal, a pattern that has been described for human strabismic amblyopes.

A Retrospective Analysis of Pituitary Apoplexy

Thirty-seven patients with pituitary apoplexy were analyzed with an emphasis on clinical presentation and visual outcome. Their mean age was 56.6 years, with a male to female ratio of 2:1. Presenting symptoms included headache (95%), vomiting (69%), ocular paresis (78%), and reduction in visual fields (64%) or acuities (52%). Computed tomographic scanning correctly identified pituitary hemorrhage in only 46% of those scanned. Thirty-six patients underwent transsphenoidal decompression. By immunostaining criteria, null-cell adenomas were the most frequent tumor type (50%). Long-term steroid or thyroid hormone replacement therapy was necessary in 82% and 89% of patients, respectively. Long-term desmopressin therapy was required in 11%, and 64% of the male patients required testosterone replacement therapy. Surgery resulted in improvement in visual acuity deficits in 88%, visual field deficits in 95%, and ocular paresis in 100%. Analysis of the degree of improvement in preoperative visual deficits with the timing of the surgery demonstrated that those who underwent surgery within a week of apoplexy had significant recovery in their visual acuities. In the stable, conscious patient with residual vision in each eye, surgical decompression should be performed as soon as possible, because delays beyond 1 week may retard the return of visual function.

'Correctable undetected visual acuity deficit' in patients aged 65 and over attending an accident and emergency department.

The rate of occurrence of correctable undetected visual acuity deficit (CUVAD) in a population of patients aged 65 and over was investigated, using a pinhole screening method, to compare the sociodemographic and optical eye care habits of patients with or without a functionally significant CUVAD. Of 136 patients 46 (34%) were found to have a functionally significant CUVAD in one or both eyes which was not significantly associated with optician or general practitioner contact, age, sex, social class, living situation, or number of medications. Half the patients with significant CUVAD had not attended for 2 years mainly because of financial considerations. Three quarters attended of their own volition; only one in seven were prompted by opticians' postal invitations. It was concluded that a significant degree of CUVAD could be detected using a simple procedure which can be carried out by general practitioners as part of their general elderly health screen.