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PubMed2003

Cost of glaucoma in Canada: analyses based on visual field and physician's assessment.

PURPOSE: A longitudinal, retrospective study investigated the cost of primary open angle glaucoma (POAG). METHODS: Patient files from two tertiary care glaucoma practices were reviewed. Patients diagnosed with POAG and >/=2.5 years of follow-up data were included. Data collected included visual field mean deviation, physician's assessment, and resource utilization (physician visits, procedures, and medications). Costs, reported in 2001 Canadian dollars, were compared between groups, based on initial visual field mean deviation, including mild (<5 dB), moderate (5 to <12 dB), and severe (>/=12 dB), and based on physician's assessment, including controlled, uncontrolled, or patients initially uncontrolled for 12 months who become controlled. RESULTS: Of 411 patient charts extracted, 265 were included; 35 were excluded for ocular comorbidities and 111 patients with insufficient follow-up. Mean (standard deviation) yearly costs overall (N = 265) and for mild (n = 90), moderate (n = 91), and severe (n = 84) groups were $508 ($278), $408 ($266), $512 ($288), and $609 ($243), respectively. Differences between mean yearly costs were statistically significant for all three groups (P < 0.05). Costs for controlled (n = 110), uncontrolled (n = 76), and uncontrolled then controlled group (n = 79) were $423 ($243), $594 ($314), and $542 ($256), respectively. The controlled group cost was significantly lower than both of the other groups (P < 0.05). DISCUSSION AND CONCLUSIONS: The cost of treating POAG increases with visual field mean deviation severity and uncontrolled disease. Many patients diagnosed with glaucoma had already progressed to later stages in the disease process. Early disease detection may provide a substantial cost savings to the health care system.

Canada↗

PubMed1996

Visual field progression: comparison of Humphrey Statpac2 and pointwise linear regression analysis.

BACKGROUND: Humphrey Statpac2 "glaucoma change probability analysis' is a widely available analysis technique to aid the clinician in the diagnosis of glaucomatous visual field deterioration. A comparison of this technique with the more recently described pointwise linear regression analysis (PROGRESSOR) is given. METHODS: Series of visual field data from a group of nine eyes of nine patients with normal-tension glaucoma were selected. Each series had 16 fields with mean follow-up of 5.7 years (SD 0.6 years). Statpac2 "glaucoma change probability analysis' was used to define test locations that had unequivocally deteriorated in the last three fields of each series. The accuracy of both Statpac2 and PROGRESSOR in providing early detection of these deteriorated locations was assessed. RESULTS: The sensitivity and specificity of the two techniques in predicting deteriorated locations were similar when a rate of luminance sensitivity loss of faster than 1 dB/year (2 dB/year for outer locations beyond 15 deg of eccentricity) with a slope significance of P < 0.10 was used as the regression definition of deterioration. The difficulties of comparing two techniques in the early diagnosis of field progression without a true external standard for field loss are illustrated. CONCLUSIONS: PROGRESSOR closely emulates the performance of Statpac2 in detecting sensitivity deterioration at individual test locations. This new technique, which uses all available data in a field series and gives the rate of sensitivity loss at each location, may provide a clinically useful method for detecting field progression in glaucoma.

Disease Progression↗

PubMed2007

Frequency doubling technology perimetry in open-angle glaucoma eyes with hemifield visual field damage: comparison of high-tension and normal-tension groups.

PURPOSE: To evaluate the performance of frequency doubling technology (FDT) perimetry in open-angle glaucoma eyes with hemifield visual field damage and to compare it between open-angle glaucoma with high pressure [high-tension glaucoma (HTG)] and those with normal pressure [normal-tension glaucoma (NTG)] groups. METHODS: FDT perimetry with the N-30 full threshold protocol and standard automated perimetry (SAP) using the Humphrey Field Analyzer with the 30-2 full threshold protocol were performed in 20 eyes of 20 HTG patients and 36 eyes of 36 NTG patients with visual field damage confirmed with SAP in only one hemifield. RESULTS: There was no significant difference in demographics, the Heidelberg Retina Tomography indices, and the Humphrey Field Analyzer indices between HTG and NTG groups. Regarding the FDT perimetry results, mean deviation in the global field (P=0.009) and mean sensitivity in the SAP-spared (P=0.001) and SAP-impaired (P=0.011) hemifields were lower; the numbers of FDT abnormal test points (probability of abnormality <5%) in the SAP-spared hemifield were significantly greater (P=0.005) in HTG than in NTG groups. Eyes in which FDT results of the SAP-spared hemifield were judged as abnormal was more frequent in HTG groups (P=0.007). CONCLUSIONS: The performance of FDT perimetry to detect early or preperimetric glaucomatous functional changes should be different between HTG and NTG eyes.

Cross-Sectional Studies↗

PubMed2001

[Ocular hemodynamics and visual field in glaucoma treated with dorzolamide].

OBJECTIVE: It has been shown that oral carbonic anhydrase inhibitors improve visual function in glaucoma. Furthermore topical dorzolamide might improve ocular hemodynamics, as was demonstrated previously. This study was undertaken to evaluate whether topical dorzolamide affects visual function and ocular hemodynamics in glaucoma. METHODS: In a retrospective, open clinical trial, dorzolamide eye drops were administered to 28 patients with confirmed primary open angle glaucoma (POAG) in both eyes, 3 times daily for a mean follow up of 9 months. One eye was randomly chosen for evaluation. IOP, blood pressure, heart rate, pulsatile ocular blood flow (POBF) and Humphrey 30-2 visual fields were measured at baseline and after the start of the therapy. POBF was determined by pneumotonography. For statistical analysis the Wilcoxon-matched-paired test and the Bonferoni-Holm adjustment were used. RESULTS: In dorzolamide-treated patients the IOP dropped from 18 mmHg to 15.5 mmHg after 9 months therapy (p < 0.01) and the visual field improved significantly by 18% (p < 0.05). A statistically significant change was found for POBF from 543 microliters/min to 675 microliters/min (p < 0.05). CONCLUSIONS: The results showed the expected drop in intraocular pressure. Visual function and pulsatile ocular blood flow improved significantly which might be explained by an analogous, vasodilatory effect as was observed in orally applied carbonic anhydrase inhibitors.

Aged↗

PubMed2005

Combining perimetric suprathreshold and threshold procedures to reduce measurement variability in areas of visual field loss.

PURPOSE: Several current perimetric test strategies use information from neighboring test locations to seed the procedure. When this initial estimate is close to the true threshold, the algorithms terminate quickly with low error. However, when neighboring thresholds are dissimilar, seeding procedures in this manner results in poor accuracy and repeatability. This study aims to develop a test procedure that avoids assumptions based on neighboring locations yet terminates with an acceptable number of presentations. We explore the utility of a combined screening and threshold approach. METHODS: Our approach [estimation minimizing uncertainty (EMU)] first applies suprathreshold screening and then in those locations that fail the screening, a ZEST procedure commencing with a uniform probability density function (pdf). EMU was compared with full threshold (FT) using computer simulation. Input to the simulation was empirical standard automated perimetry data (FT) from 265 normal subjects and 163 observers with glaucomatous visual field loss. Test performance was assessed using four patient error models designed to represent patients who respond with no errors, typical false-positive errors, typical false-negative errors, and extremely unreliable patients. RESULTS: When patients made typical false-positive errors, EMU required about 20% fewer presentations than FT averaged across the visual field. EMU required a greater number of presentations than FT when false-negative errors were made. The percentage of locations misclassified as either normal (defined as the thresholds greater than the lower 95% confidence limit of age-corrected norms) or abnormal by EMU was lower than for FT. Point-wise analysis demonstrated that in the presence of false-positive errors, the average error and SD of error of thresholds returned by EMU were reduced compared with FT. CONCLUSIONS: EMU enabled accurate estimates of threshold for situations in which neighboring locations are a poor predictor of true threshold. Combining suprathreshold and threshold strategies enables an acceptable number of total visual field presentations, while improving the accuracy and repeatability of threshold estimates in regions of abnormal sensitivity.

Computer Simulation↗

PubMed1981

[Correlation of infarctions of the visual cortex with homonymous visual field defects. A computer tomographic study (author's transl)].

Computed tomography (CT) is a simple and non-invasive method of demonstrating infarctions of the visual cortex. Seventy-eight CT-proven infarctions were correlated with the visual field defects. This correlation between cortical infarctions and visual field defects is difficult to achieve by angiography because of the variations in the vascular supply. CT, on the other hand, provides a far better correlation, showing the functional-anatomical structure of the visual cortex by projection in three planes (transverse, sagittal, coronar). CT, however, can not replace angiography in cases where arteriovenous malformations are suspected.

Acute Disease↗

PubMed2000

Deficit-undamaged visual field area monitoring in glaucomatous patients with advanced perimetric damage: its usefulness.

This report contains the observations of the authors on the behaviour with time of the visual field areas (VF) which appear undamaged by deficit within the perimetric findings where at the same time there is advanced glaucomatous damage. A retrospective study has been made on the records of a Humphrey perimeter 640 VFA relating to glaucomatous patients with these perimetric characteristics in whom at least 12 examinations (programme "Central 30-2 threshold test") had been made and who, for a good part of the period of observation at least, had recorded a topographic stability of the deficits. There were found 12 series of examinations responding to the required necessities. The analysis of the findings used a method that separated from the global mean deviation (MD) that part concerning the pathological area and that referring to the "healthy" area of the visual field (VF). In 7 of the 8 cases where, at a certain point in the follow-up, there became evident a trend towards worsening, there was also a significant increase in the MD of the undamaged, which occurred before the deterioration of the "healthy" area became evident by the appearance of "probability symbols" in the "total deviation" map. In the 4 cases where there was stability with time, the MD values relating to the undamaged area of the VF were quite constant with time.

Chronic Disease↗

PubMed1982

Binocularity in comitant strabismus: binocular visual fields studies.

A critical review is made of the literature on binocular perimetry in strabismus. A broad range of results was obtained by various authors, because different testing techniques were used. The concept of sensory testing of strabismic patients in casual seeing condition should be introduced also into binocular perimetry. Therefore a series of experiments is presented in which patients with small-angle comitant strabismus were tested. It was shown that: a) in small-angle esotropia the areas of single vision previously thought to be due to suppression are, instead, areas of binocular vision sustained by anomalous retinal correspondence (ARC); b) this can be seen only when using fusable stimuli as test targets; c) no suppression scotomas were found in patients with small-angle strabismus in the whole visual field; d) appropriate control-marks for binocularity are necessary, i.e. monocularly presented items. They influence the results, as well e) the area of binocular single vision in strabismus (called pseudo-Panum's area) is wider than the Panum's area of normals. Moreover it is easier to disrupt binocular cooperation sustained by ARC causing diplopia than binocular cooperation in normals; f) ARC seems to be more deeply rooted in the center than in the periphery of the visual field; g) superimposable findings were obtained in small-angle constant exotropia; h) in large-angle exotropia wide suppression scotomas were found, which often override the midline. Hemianopic suppression scotomas in exotropia can be found only when 'dissociating' testing techniques are used; i) the same group of patients with small-angle esotropia was examined with the author's technique and with the classical method proposed by Harms. The results were strongly dependent on the method used and the same patient responded differently to the two tests. It is concluded that in small-angle strabismus there is an anomalous type of binocular single vision, which can be tested with binocular visual field techniques. This binocularity can only be found when non-artificial testing conditions are used. The usefulness of this anomalous binocular vision in the every day seeing condition of the patient is discussed.

Depth Perception↗

PubMed1998

[Association between watershed zone and visual field defect in normal tension glaucoma].

In order to evaluate the association between the watershed zone and glaucomatous optic damage, we performed indocyanine green fluorescence angiography with a scanning laser ophthalmoscope in 54 eyes of 27 patients with normal tension glaucoma. The visual field indices were measured with a Humphrey Field Analyzer. We identified 8 eyes (14.8%) of 7 patients with a watershed zone not including the optic nerve head (type I), 32 eyes (59.3%) of 20 patients with the zone partially including the optic nerve head (type II), and 14 eyes (26.0%) of 10 patients with the zone including the optic nerve head (type III). Of the total of 27 patients, 10 patients (37.0%) had different types in each eye. In these patients, the mean deviation (MD) of visual field indices was worse in the eye with the watershed zone which included a larger part of the optic disc than in the contralateral eye (p < 0.05). Conversely, the eye with worse MD than the contralateral eye had a watershed zone which included a larger part of the optic disc than the other eye (p < 0.05). The location of watershed zone appeared to influence the progression of the visual field defect.

Adult↗

PubMed2005

Effect of the menstrual cycle on standard achromatic and blue-on-yellow visual field analysis of women with migraine.

BACKGROUND: It has been postulated that migraine and glaucoma may have common vascular causative factors. Significant sex-based differences in the incidence of many important ocular conditions raise the possibility that estrogens may have direct effects on the eye. We performed a study to determine the effect of the menstrual cycle on standard achromatic automated perimetry (SAP) and short-wavelength automated perimetry (SWAP) (blue-on-yellow perimetry) of women with migraine. METHODS: Both eyes of 73 normally menstruating women (31 subjects with migraine and 42 healthy control subjects) were included in the study. Subjects underwent a complete ocular examination including SAP and SWAP in both the follicular phase (12th to 13th day of the cycle) and the luteal phase (1 to 2 days before the onset of bleeding) of two consecutive menstrual cycles.We performed visual field analysis using the Humphrey Field Analyzer II with the full-threshold central 30-2 program. Mean sensitivity was calculated for the superior temporal, inferior temporal, superior nasal and inferior nasal regions separately. RESULTS: Thirteen subjects were lost to follow-up (5 in the migraine group and 8 in the control group), leaving 26 subjects and 34 subjects respectively. There was no significant difference in mean age between the two groups (33.9 years [standard deviation (SD) 3.4 years] vs. 35.1 years [SD 3.3 years]). The mean duration of migraine was 7.6 (SD 3.1) years (range 3-14 years). In both groups, serum estradiol levels were significantly lower (p = 0.001) and serum progesterone levels were significantly higher (p < 0.001) in the luteal phase than in the follicular phase. In the control group, the mean sensitivity values with SWAP were significantly lower in the luteal phase than in the follicular phase (p = 0.04). A similar decrease was observed for the subjects with migraine with both SAP and SWAP (p = 0.01). There was no difference in regional mean sensitivity between the two phases with either perimetric test in the control group. For the subjects with migraine, there was no difference in regional mean sensitivity between the two phases with SAP. However, with SWAP, the mean sensitivity for the nasal visual field locations was significantly lower in the luteal phase than in the follicular phase (p = 0.01). INTERPRETATION: Our study provides further evidence of an effect of sex hormones on the visual field of women with migraine. In addition to assessment of intraocular pressure, menstrual cycle phases should be considered in women with migraine at risk for glaucomatous optic neuropathy.

Adult↗

PubMed1999

Improving awareness of peripheral visual field using sectorial prism.

BACKGROUND: The authors wish to alert optometrists that an increased awareness of peripheral visual field is possible in selected patients with complete homonymous hemianopsia through the use of ground-in sectorial prisms. METHOD: A case series of nine patients prospectively completed activities of daily living (ADL) questionnaires before and after the use of sectorial prism spectacles for the treatment of complete homonymous hemianopsias. RESULTS: Of the nine enrolled patients, seven reported subjective quantitative improvement in ADL scores on questionnaire responses and two patients did not report improvement. CONCLUSION: Patients with homonymous hemianopic visual-field loss may improve their functional vision and activities of daily living through the use of hemianopic prism spectacles. These sectorial prisms--along with proper training--may enhance peripheral awareness through more efficient visual scanning skills.

Adaptation, Ocular↗

PubMed2001

A comparison of upper vs. lower and right vs. left visual fields using lexical decision.

A series of experiments using the lexical decision task was conducted in order to investigate the functional differences between the upper and lower visual fields (UVF, LoVF) in word recognition. Word-nonword discrimination was swifter and more accurate for word stimuli presented in the UVF. Changing the eccentricity did not affect the UVF advantage over the LoVF. UVF superiority over LoVF was found to be equivalent for both right and left visual hemifield (RVF, LVF). In general, presenting related word primes enhanced all visual field differences in a similar manner (UVF over LoVF and RVF over LVF). However, primes consisting of semantically constraining sentences enhanced the RVF advantage over the LVF, but did not affect the UVF and LoVF differentially. The argument is made that UVF superiority cannot be due to perceptual or attentional differences alone, but must also reflect top-down information flow.

Adult↗

PubMedDate not supplied

A curriculum for training patients with peripheral visual field loss to use bioptic amorphic lenses.

This article describes the experimental protocol used to instruct fifteen patients with peripheral visual field loss due to retinitis pigmentosa, choroideremia, or Usher's syndrome Type II how to effectively use bioptic amorphic lenses. The factors that contributed to the successful use of these lenses, as well as difficulties the patients encountered, are discussed. The results of the study (published in detail in Szlyk et al. Use of bioptic amorphic lenses to expand the visual field in patients with peripheral loss. Optom Vis Sci 1998;75:518-24) indicate that bioptic amorphic lenses, when combined with a comprehensive training program, can expand visual function in the areas of peripheral detection, recognition, scanning, tracking, visual memory, and mobility.

Adult↗

PubMed1995

Quadrant analysis of peripheral colour contrast thresholds can be of significant value in the interpretation of minor visual field alterations in glaucoma suspects.

Peripheral colour contrast thresholds were investigated in glaucoma suspects with no or minor visual field alterations, determining the average colour contrast threshold at 12.5 degrees off axis. The technique was introduced as a rapid screening test for pre-glaucomatous visual loss. Using this 'ring' test, all definite glaucoma patients in the initial study had elevated colour contrast thresholds. In our experience, however, a substantial proportion of early glaucoma patients were found to have normal thresholds. The peripheral colour contrast threshold determined by the ring test is an average threshold in the entire annular zone at 12.5 degrees eccentricity. We therefore modified the test procedure without a major increase in test duration. An arcade subtending 45 degrees at 12.5 degrees eccentricity was used to determine colour contrast thresholds in four quadrants of the visual field separately ('quadrant' test). We present here the first results of this novel procedure, investigating peripheral colour contrast thresholds in glaucomatous patients. The quadrant test is shown to be more sensitive than the ring test in the detection of functional loss.

Adult↗

PubMed2002

Visual field defects and neural losses from experimental glaucoma.

Glaucoma is a relatively common disease in which the death of retinal ganglion cells causes a progressive loss of sight, often leading to blindness. Typically, the degree of a patient's visual dysfunction is assessed by clinical perimetry, involving subjective measurements of light-sense thresholds across the visual field, but the relationship between visual and neural losses is inexact. Therefore, to better understand of the effects of glaucoma on the visual system, a series of investigations involving psychophysics, electrophysiology, anatomy, and histochemistry were conducted on experimental glaucoma in monkeys. The principal results of the studies showed that, (1) the depth of visual defects with standard clinical perimetry are predicted by a loss of probability summation among retinal detection mechanisms, (2) glaucomatous optic atrophy causes a non-selective reduction of metabolism of neurons in the afferent visual pathway, and (3) objective electrophysiological methods can be as sensitive as standard clinical perimetry in assessing the neural losses from glaucoma. These experimental findings from glaucoma in monkeys provide fundamental data that should be applicable to improving methods for assessing glaucomatous optic neuropathy in patients.

Animals↗

PubMed1985

A clinical comparison of visual field testing with a new automated perimeter, the Humphrey Field Analyzer, and the Goldmann perimeter.

Automated threshold static perimetry with the Humphrey field analyzer and kinetic and suprathreshold static perimetry with the Goldmann perimeter were performed on 171 eyes: 69 with glaucoma or ocular hypertension, 69 with "neurologic" disorders, and 33 normal. The two fields were similar or differed only slightly in 78% of eyes overall and in 88% when both fields appeared reliable. In general, defects were slightly more extensive using the Humphrey than the Goldmann perimeter. In 21% of the eyes with glaucoma or ocular hypertension, defects were found with the Humphrey perimeter that were not present with the Goldmann perimeter. Patient fixation was more difficult to maintain on the Humphrey than Goldmann perimeter. Poor fixation accounted for 9% of the automated fields being inadequate whereas only 2% of the manual fields were inadequate. The results indicate that the Humphrey Field Analyzer is capable of reliably detecting and quantitating visual field defects.

Adolescent↗

PubMed1991

[Diffuse and localized glaucomatous visual field changes in light sense, flicker and visual acuity perimetry. Evidence of pressure damage].

75 eyes of 75 patients with different types of glaucoma (21 eyes with normal-tension glaucoma, 49 eyes with primary open-angle glaucoma and 5 eyes with pigmentary glaucoma) were examined by automated light-sense, flicker and resolution perimetry. All fields were classified as being "normal" (N) or having "diffuse loss" (D), "localized loss" (L) and "diffuse plus localized loss" (DL) in masked fashion. The frequency distributions for the various field loss categories against the highest intraocular pressure ever reported in the patients' records were plotted. The frequency distributions for the purely localized defects show a peak at 20 mmHg and are markedly skewed to low pressure values, while the diffuse plus localized damage and the purely diffuse loss, however, show a peak at about 30 mmHg. The data support the hypothesis that diffuse field loss may be an indicator of pressure-induced damage.

Adult↗

PubMed1987

Mechanisms for binocular depth sensitivity along the vertical meridian of the visual field.

By removing the visual cortex unilaterally, and recording along the intact 17/18 border, we have investigated the influence of the corpus callosum on the tuning curves for stimulus disparity of cat cortical neurons. Responses to binocular stimulation were examined to movement in the same (in-phase) and in the opposite direction (antiphase) across the two retinae. In lesioned cats, as in normal cats, units were encountered which showed high sensitivity and narrow tuning for stimulus disparity. In contrast to normal cats, however, lesioned cats showed a reduced proportion of units displaying moderate binocular interactions, as well as a substantial increase in disparity-insensitive cells. The loss of disparity sensitivity after decortication was associated with a reduced incidence of both selectivity for the direction of stimulus motion and binocular activation. No large differences between the preparations were seen, however, in the ocular dominance of the total populations of cells. Differences between the normal and lesioned cats were found in binocular responses to in-phase but not to antiphase stimulation motion. Tuning curves in lesioned cats showed reduced binocular inhibition but no changes in binocular facilitation. Our findings indicate that callosal input contributes to unit disparity sensitivity by enhancing direction-selective binocular inhibition. The corpus callosum generates disparity sensitivity in a population of units in the superficial cortical layers which may play a particular role in the perception of stereoscopic depth.

Animals↗