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Department of Ophthalmology, Sun Yat-sen
Memorial Hospital, Sun Yat-sen University of Medical Sciences,
Guangzhou 510120, China.
OBJECTIVE: The study was designed
to analyze the relationship among the three electrophysiological
tests and visual fields in primary open angle glaucoma (POAG)
in order to find some more sensitive and specific parameters
in earlier and early diagnosis of patients with POAG. METHODS:
Thirty-six(70 eyes) patients with POAG, 8(12 eyes) glaucoma
suspects and 30 (60 eyes) normal subjects underwent pattern
electroretinogram (PERG), oscillatory potentials (OPs),
pattern visual evoked potentials (PVEP) and Humphery automated
perimetry tests respectively. RESULTS: The abnormal rate
of PERG was the highest among the three electrophysiological
tests in the glaucoma suspects and those of PERG and automated
perimetry results were higher than others after early stage.
In the correlation analysis of all objects, the amplitude
of PERG had negative correlated with IOP and visual indices,
but no correlation with C/D and VA. OPs had negative correlated
with C/D, and no correlation with visual fields indices,
intraocular pressure (IOP) and visual acuity (VA). The latency
of PVEP had positive correlation with visual fields indices
and C/D, but no correlation with IOP. CONCLUSION: Statistical
result showed that different parameters could be selected
according to different appearance of POAG. In the earlier
stage before visual field defects could be found, PERG would
be a more sensitive indicator if IOP were high; once C/D
was abnormal, OPs and PVEP would be the better signs even
though IOP was normal. PERG and Humphery automated perimetry
were very useful indicators after early stage. It was significant
in combination of many visual function tests on earlier
or early diagnosis of POAG.
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Augenklinik mit Poliklinik, Univ. Erlangen-Nurnberg.
BACKGROUND: Of the three glaucoma-defining
criteria intraocular pressure, optic-nerve damage, and visual
field damage, the latter is a late symptom. Therefore, in
order to improve an early sensory diagnosis, new tests are
necessary. It is the aim of the present paper to test new
sensory methods, to rank them in an order of sensitivity,
and to base them on possible pathophysiological mechanisms.
PATIENTS AND METHODS: The tests were carried out in subjects
of the Erlangen Glaucoma registry: Normals, patients with
ocular hypertension, and patients with open-angle glaucoma
without or with field defects. The tests are designed to
preferentially probe the function of different groups of
ganglion cells. Psychophysical methods: Temporal contrast
sensitivity in a ganzfeld as "Erlangen flicker test"
and spatio-temporal contrast sensitivity to test Magno-cell
function. Electrophysiological methods: Pattern-reversal
electroretinogram with a luminance-contrast pattern to test
Magno-cell function, color-contrast pattern electroretinogram
for Parvo-cell function, and blue-on-yellow visual evoked
potential to test the "blue-sensitive" pathway.
RESULTS: The most sensitive test is the temp.CS, it is significantly
reduced in OHT (p < 0.01). The spatio-temp.CS is reduced
in perimetric stages (p < 0.01). The BY-VEP is altered
in the preperimetric stage (p < 0.01), the PR-ERG in
perimetric stages (p < 0.01). The CC-ERG is reduced in
even later stages. These results are in agreement with the
hypothesis that tests selective for non-redundant neurons
are of early diagnostic value. Multivariate analyses increase
the early diagnostic value when different functions are
tested in combination. CONCLUSIONS: When a particular test
is taylored to the the special needs of certain groups of
ganglion cells sensory defects can be observed before the
occurrence of optic-nerve damage (OHT). The most sensitive
psychophysical test is the "Erlangen flicker test"
which is a screening test selective for M cells. The most
sensitive electrophysiological test is the BY-VEP testing
the blue-sensitive ganglion cells.
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Zhongshan Ophthalmic Center, Sun Yat-sen
University of Medical Sciences, Guangzhou.
OBJECTIVE: To evaluate the application
of high-pass resolution perimetry (HRP) in detecting the
early visual field loss of glaucoma. METHOD: According to
the method described by Frisen, we developed HRP in a personal
computer. The HRP was used to examine the visual field of
22 normal subjects (44 eyes), 27 cases (41 eyes) of primary
open-angle glaucoma (POAG) with abnormal automated visual
fields and 10 cases (13 eyes) of early POAG or suspected
POAG with normal automated visual fields. RESULTS: The mean
resolution threshold in the normal subjects was 3.96+/-
0.55db in the right eyes and 3.98+/- 0.55dB in the left
eyes. It is demonstrated that HRP was more sensitive than
automated perimetry in detecting the glaucomatous visual
field defects, its sensitivity was 93.75% and specificity
was 97.7%. The early visual field loss of glaucoma might
present increment of the retinal resolution threshold. CONCLUSION:
HRP is a relatively sensitive method for the detection of
the early visual field loss in POAG, and it can be used
extensively.
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Department of Ophthalmology, Friedrich-Alexander-University
Erlangen-Nurnberg, Germany.
PURPOSE: To evaluate whether the
full-field flicker test, a psychophysical test employing
full-field flickering stimuli to measure temporal contrast
sensitivity, can detect glaucomatous optic nerve damage
in patients with increased intraocular pressure and glaucomatous
optic disk abnormalities but normal visual fields. METHODS:
Temporal contrast sensitivity was determined with a sinusoidally
flickering light (frequency, 37.1 Hz) of constant mean photopic
luminance (10 cd/m2) presented in a full-field bowl of 58-cm
diameter. The prospective study included three groups of
individuals: the "preperimetric" glaucoma group
of 80 patients with increased intraocular pressure, glaucomatous
optic disk abnormalities, and normal visual fields; the
"perimetric" glaucoma group of 56 glaucomatous
patients with increased intraocular pressure and glaucomatous
changes of the optic disk and visual field; and the control
group of 96 normal subjects. RESULTS: Temporal contrast
sensitivity was significantly (P < .001) lower in the
two glaucoma groups than in the control group. In the preperimetric
glaucoma group, 34% of the patients (27/ 80) were recognized
by the full-field flicker test at a specificity of 99%.
For all study subjects, temporal contrast sensitivity decreased
significantly (P < .001) with decreasing neuroretinal
rim area, enlarging peripapillary atrophy, and diminishing
retinal nerve fiber layer visibility. CONCLUSIONS: The full-field
flicker test can detect glaucomatous optic nerve damage
in patients with increased intraocular pressure, glaucomatous
optic disk abnormalities, and normal visual fields. Considering
its feasibility, simplicity, quick performance, and low
costs, the full-field flicker test may be helpful in clinics
and in screening examinations as a supplement to glaucoma
diagnosis.
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University of Erlangen-Nurnberg.
This review reports findings of the
recent literature about electrophysiologic techniques that
are used in glaucoma diagnosis and research. Included in
this review are results obtained by recording electrical
responses from the eye (electroretinograms) and from the
brain (visual evoked potentials). Studies concerned the
electroretinogram evoked by patterned stimuli that originates
in the proximal retina and with flash-evoked responses that
originate from the proximal retina, such as oscillatory
potentials and scotopic threshold responses, from middle
layers of the retina (B wave), and from the outer retina
(A waves and C waves). Regarding the pattern electroretinogram,
the authors agree on its usefulness in the diagnosis of
glaucoma. However, the optimal stimulus conditions (temporal
and spatial frequency, retinal location, contrast, and color),
which component of the response to evaluate, and the value
of the pattern electroretinogram in follow-up treatment
are debatable. Flash-evoked components of the electroretinogram
that have been considered in the past to be of low value
in diagnosis of glaucoma now seem to be more important.
New developments in visual evoked potentials techniques,
such as photostress methods, contrast sensitivity measurements,
ramp stimulation, and selective adaptation for isolating
blue-cone activity seem to be promising in further increasing
the diagnostic value of visual evoked potential measurements.
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In a group of 46 patients with moderately
elevated intraocular pressure (22-30 mmHg), signs of early
glaucoma were found in half of them after a follow-up of
5-7.5 years. Most of the patients showed only a small increase
in optic disc cupping revealed by stereophotography. Initial
IOP higher than 25 mmHg, large pressure differences between
the two eyes, large diurnal pressure variation, occurrence
of pseudoexfoliation, pressure drop of more than 8 mmHg
after topical epinephrine, and a pressure rise of more than
4 mmHg after water loading were more frequent in the group
of patients who developed signs of glaucoma. Age, a positive
family history, occurrence of cardiovascular disease, and
the cup/disc ratio did not differ in the two groups of patients.
The pilocarpine test and steroid provocation had no predictive
value. Surprisingly, there was a small drop of pressure
after topical steroids in 6 of the 8 patients with pseudoexfoliation.
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Department of Neuroradiology, Hospital
of the University of Pennsylvania, Philadelphia 19104.
OBJECTIVE. The purpose of this study
was to determine whether the CT attenuation value of the
lens is helpful in diagnosing acute traumatic cataracts
in patients with complicated eye injuries that preclude
evaluation by any other means. SUBJECTS AND METHODS. The
CT attenuation values of the lenses of 69 patients with
acute orbital trauma, including 24 patients with clinically
and surgically diagnosed acute traumatic cataracts, were
compared with attenuation values of their own contralateral
lens and with the attenuation values of the lenses of 103
consecutive asymptomatic control subjects. The study group
was composed of consecutive patients with unilateral orbital
trauma who were clinically evaluated and referred for CT
examination within 48 hr after their initial injury. In
all patients, attenuation measurements of the injured lenses
were obtained and compared with those of the contralateral
lens as an internal control. All surgically diagnosed cataracts
were histologically confirmed. RESULTS. The CT attenuation
measurement of a lens in any asymptomatic control subject
was identical (within the range of the standard deviation)
to the measurement of the contralateral lens of that control
patient. In patients with orbital injury, the CT attenuation
of the patient's cataractous lens was markedly lower than
in the contralateral lens (mean density difference, 30 H,
p < .0001). This decreased attenuation corresponds to
acute cataract formation with increased fluid within the
lens. No patient with normal attenuation values of the lens
in the traumatized globe (as compared with the contralateral
lens) was found to have an acute traumatic cataract or have
a cataract develop within a 1-year follow-up period. CONCLUSION.
CT may be useful in the examination of patients with acute
traumatic cataracts, unsuspected lens injury, opacification
of the anterior chamber, or other injuries of the globe
with complications that preclude lens evaluation by any
other means. This prompt diagnosis may allow timely removal
of the lens in appropriate clinical circumstances, preventing
damage to the anterior chamber of the globe and other complications
of delayed diagnosis and treatment. Further, normal CT findings
at the time of trauma suggest that the lens will not undergo
acute traumatic cataract formation.
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