Test-retest variability of frequency-doubling perimetry and conventional perimetry in glaucoma patients and normal subjects.
PURPOSE: To compare the test-retest variability characteristics of frequency-doubling perimetry, a new perimetric test, with those of conventional perimetry in glaucoma patients and normal control subjects. METHODS: The study sample contained 64 patients and 47 normal subjects aged 66.16+/-11.86 and 64.26+/-7.99 years (mean +/- SD), respectively. All subjects underwent frequency-doubling perimetry (using the threshold mode) and conventional perimetry (using program 30-2 of the Humphrey Field Analyzer; Humphrey Instruments, San Leandro, CA) in one randomly selected eye. Each test was repeated at 1-week intervals for five tests with each technique over 4 weeks. Empirical 5th and 95th percentiles of the distribution of threshold deviations at retest were determined for all combinations of single tests and mean of two tests, stratified by threshold deviation. The influence of visual field eccentricity and overall visual field loss on variability also were examined. RESULTS: Mean test time with frequency-doubling perimetry in patients and normal control subjects was 5.90 and 5.25 minutes, respectively, and with conventional perimetry was 17.20 and 14.01 minutes, respectively. In patients, there was a significant correlation between the results of the two techniques, in the full field and in quadrants, whereas in normal subjects there was no such correlation. In patients, the retest variability of conventional perimetry in locations with 20-dB loss was 120% (single tests) and 127% (mean tests) higher compared with that in locations with 0-dB loss. Comparative figures for frequency-doubling perimetry were 40% and 47%, respectively. Variability also increased more with threshold deviation in normal subjects tested with conventional perimetry. In both patients and normal subjects, variability increased with visual field eccentricity in conventional perimetry, but not in frequency-doubling perimetry. Both techniques showed an increase in variability with overall visual field damage. CONCLUSIONS: Frequency-doubling perimetry has different test-retest variability characteristics than conventional perimetry and may have potential for monitoring glaucomatous field damage. (+info)
Post-traumatic pituitary apoplexy--two case reports.
A 60-year-old female and a 66-year-old male presented with post-traumatic pituitary apoplexy associated with clinically asymptomatic pituitary macroadenoma manifesting as severe visual disturbance that had not developed immediately after the head injury. Skull radiography showed a unilateral linear occipital fracture. Magnetic resonance imaging revealed pituitary tumor with dumbbell-shaped suprasellar extension and fresh intratumoral hemorrhage. Transsphenoidal surgery was performed in the first patient, and the visual disturbance subsided. Decompressive craniectomy was performed in the second patient to treat brain contusion and part of the tumor was removed to decompress the optic nerves. The mechanism of post-traumatic pituitary apoplexy may occur as follows. The intrasellar part of the tumor is fixed by the bony structure forming the sella, and the suprasellar part is free to move, so a rotational force acting on the occipital region on one side will create a shearing strain between the intra- and suprasellar part of the tumor, resulting in pituitary apoplexy. Recovery of visual function, no matter how severely impaired, can be expected if an emergency operation is performed to decompress the optic nerves. Transsphenoidal surgery is the most advantageous procedure, as even partial removal of the tumor may be adequate to decompress the optic nerves in the acute stage. Staged transsphenoidal surgery is indicated to achieve total removal later. (+info)
Characteristics of discrepancies between self-reported visual function and measured reading speed. Salisbury Eye Evaluation Project Team.
PURPOSE: Visual impairment is a risk factor for morbidity in the elderly and is often screened for by self-report. This study evaluates whether there are subsets for whom there is a discrepancy between self-reported and measured function. METHODS: The prevalence of a discrepancy between self-reported difficulty reading a newspaper and measured reading speed was determined in 2520 community-based men and women, aged 65 to 84 years, and the discrepant group characterized by polychotomous regression. RESULTS: Of subjects who reported minimal difficulty reading a newspaper, 10.8% (227/2107) read newsprint-sized text (0.21 degrees) more slowly than 80 words/min, a level previously shown to be necessary for sustained reading. Poor visual acuity, presence of psychiatric symptoms, and less satisfaction with vision were associated with being in the group that read slowly and reported difficulty with reading. Better cognition, better visual acuity, more years of education, white race, and fewer psychiatric symptoms were associated with being in the group that read more quickly and reported minimal difficulty. When reading the text size at which subjects read their fastest, only 2.6% of those with minimal difficulty remained discrepant. These individuals were more likely to have less education, be male, be African American, and have poorer cognitive status than those who did not remain discrepant. CONCLUSIONS: A subset of the elderly population have a substantial discrepancy between self-reported reading difficulty and measured reading speed. In some, this discrepancy may be based on underlying expectations and experiences, and in others it may represent a transition from no visual impairment to visual impairment. (+info)
Space representation in unilateral spatial neglect.
Patients with unilateral brain lesions were given a task requiring exploration of space with the hand in order to assess the visual dependency of unilateral spatial neglect. The task was carried out both without visual control and under visual control. Performances were compared with that of normal subjects. Results were :(1) patients with right brain damage with no visual field defect demonstrated left-sided neglect only when the exploration was not controlled visually; (2) patients with left and right brain damage with visual field defect demonstrated contralateral neglect only when the exploration was under visual guidance. The performance of the patients with right brain damage without visual field defect in not clearly understood. The other results suggest that inner spatial representation remains intact in most cases of spatial neglect. The role of parietal lobe damage in the development of this visually induced phenomenon is hypothesised. The dominant position of vision among the senses is indicated. (+info)
Cyclic compression of the intracranial optic nerve: patterns of visual failure and recovery.
A patient with a cystic craniopharyngioma below the right optic nerve had several recurrences requiring surgery. Finally the cyst was connected with a subcutaneous reservoir by means of a fine catheter. Symptoms of optic nerve compression recurred more than 50 times during the following year, and were relieved within seconds upon drainage of the reservoir. In each cycle, a drop in visual acuity preceded a measurable change in the visual field. The pattern of field changes was an increasingly severe, uniform depression. Optic nerve ischaemia induced by compression was probably the most important factor causing visual failure in this case. (+info)
Factors associated with the poor final visual outcome after traumatic hyphema.
In order to determine the factors related to the worse final visual outcome following nonperforating traumatic hyphema, the clinical characteristics of 18 patients with visual outcome of 0.1 or worse were compared with those of 166 patients with visual outcome of 0.15 or better. The presence of posterior segment injuries such as macula edema, retinal hemorrhage, epiretinal membrane, and choroidal rupture were significant factors of a poor final visual outcome (P < 0.01). The presence of anterior segment injuries such as corneal blood staining, traumatic mydriasis, iridodialysis, cataract, and lens subluxation had significant predictive factors on a poor final visual outcome and the concurrent posterior segment injuries were more frequent in these patients. Initial visual acuity of 0.1 or worse, glaucoma, vitreous hemorrhage, and eyelid laceration were also significant associations of a poor final visual outcome (P < 0.05). Patients with initially larger hyphema (grade I or more vs microscopic) and older age group (16 years or more vs 15 years or less) tended to have poor final visual acuities. Rebleeding was not associated with significant deterioration in visual prognosis. We conclude that the posterior segment injuries seem to be directly related to a poor visual outcome rather than the occurrence of secondary hemorrhage. (+info)
The need for cataract surgery: projections based on lens opacity, visual acuity, and personal concern.
AIM: To assess the projected needs for cataract surgery by lens opacity, visual acuity, and patient concern. METHODS: Data were collected as part of the Melbourne Visual Impairment Project, a population based study of age related eye disease in a representative sample of Melbourne residents aged 40 and over. Participants were recruited by a household census and invited to attend a local screening centre. At the study sites, the following data were collected: presenting and best corrected visual acuity, visual fields, intraocular pressure, satisfaction with current vision, personal health history and habits, and a standardised eye examination and photography of the lens and fundus. Lens photographs were graded twice and adjudicated to document lens opacities. Cataract was defined as nuclear greater than or equal to standard 2, 4/16 or greater cortical opacity, or any posterior subcapsular opacities. RESULTS: 3271 (83% response) people living in their own homes were examined. The participants ranged in age from 40 to 98 years and 1511 (46.2%) were men. Previous cataract surgery had been performed in 107 (3.4%) of the participants. The overall prevalence of any type of cataract that had not been surgically corrected was 18%. If the presence of cataract as defined was considered the sole criterion for cataract surgery with no reference to visual acuity, there would be 309 cataract operations per 1000 people aged 40 and over (96 eyes of people who were not satisfied with their vision, 210 eyes of people who were satisfied with their vision, and three previous cataract operations). At a visual acuity criterion of less than 6/12 (the vision required to legally drive a car), 48 cataract operations per 1000 would occur and people would be twice as likely to report dissatisfaction with their vision. CONCLUSIONS: Estimates of the need for cataract surgery vary dramatically by level of lens opacity, visual acuity, and patient concern. These data should be useful for the planning of health services. (+info)
Measuring the effectiveness of cataract surgery: the reliability and validity of a visual function outcomes instrument.
AIMS: To assess test-retest reliability and validity of the "TyPE" patient self assessed visual function questionnaire, as part of a study in two hospitals measuring the effectiveness of cataract surgery. The American TyPE questionnaire had minor adaptations made for use in Britain. METHODS: Test-retest reliability was assessed on 63 out of 378 adult cataract surgery patients in the study, using Spearman correlation coefficients and kappa coefficients of agreement. "Construct" validity was evaluated by comparing the association between changes in visual function questionnaire scores after surgery, with patients' perception of change in visual function obtained by independent interview of 24 patients. RESULTS: The TyPE questionnaire items showed very good test-retest reliability. Average Spearman and kappa coefficients for 39 patients from hospital 1 were 0.93 and 0.84 respectively. Spearman and kappa coefficients of 0.9 and 0.81 were obtained for those nine patients in hospital 2 where both the test and retest questionnaires were filled in by the same people. However, for the 15 patients from hospital 2, where the questionnaire was filled in by different people in the retest, reliability was less good: the Spearman coefficients were still high, average 0.72, but the kappa coefficients were poor, 0.27. Good construct validity was exhibited, with a correlation of 0.79 between change in distance vision score from the questionnaires and the independent interview. CONCLUSIONS: The adapted TyPE questionnaire is both very reliable and has good construct validity. The kappa coefficient should be used wherever possible to evaluate reliability. The test-retest reliability and validity and practicability of other visual function questionnaires have not been assessed adequately, and further development should be carried out of all such questionnaires, so that they may be introduced into routine clinical care. (+info)