Visual rehabilitation with MP-1 biofeedback in advanced glaucoma: a crosssectional study D. Domanico1 , F. Verboschi 1, EM. Vingolo 1
1
Department of Ophthalmology, University of Rome “Sapienza”, Polo Pontino, “A.Fiorini”
Hospital, Via Firenze, 04019 Terracina (LT), Italy.
Corresponding author: Verboschi Francesca Via Cerveteri 61, 04100 Latina Mobile: +393294024963 e- mail: francesca.verboschi@libero.it
Keywords: advanced glaucoma, microperimetry, fixation, BCEA, rehabilitation.
Abstract PURPOSE: To evaluate the efficacy of
submitted to rehabilitation protocol that
visual
MP-1
consisted of: measurement of visual acuity;
(NIDEK
Reading Speed Test; Microperimetry with
Technologies Srl, Padova, Italy) in advanced
fixation study by BCEA (bivariate contour
glaucoma to improve fixation stability, retinal
ellipse
sensitivity and reading speed.
Rehabilitation
METHODS: 16 patients (20 eyes) with
training sessions, once a week, 10 minutes for
advanced primary open angle glaucoma were
each eye. Statistical analysis was performed
rehabilitation
Microperimeter
with
biofeedback
area)
and protocol
retinal
sensitivity.
consisted
of
10
using the Student’s t-test; p values less than 0.05 were considered statistically significant. RESULTS: at the end of rehabilitation protocol mean retinal sensitivity, BCEA and reading speed were improved; while BCVA had results no statistically significant. CONCLUSIONS: Rehabilitation with MP-1
Introduction
biofeedback is a useful means to improve the
Glaucoma is a complex disease that
fixation stability of patients with advanced
comprises a group of heterogeneous optic
glaucoma, to stabilize PRL and to increase
neuropathies characterized by a progressive
visual acuity improving the patient quality of
degeneration of the optic nerve head and
life.
visual field defects.[1] It affects 70 million people and is the second leading cause of blindness worldwide. It is estimated that by the year 2020, this number would rise to around 79.6 million.[1] The prevalence of glaucoma varies widely across the different ethnic groups and is significantly higher in blacks (4.7%) than in the white population (1.3%).[2] POAG may be associated with or without an elevated IOP and has an adult onset (usually >35 years) or juvenile onset (usually <35 years).[3] Glaucoma is characterized by irreversible damage to the retinal nerve fiber layer (RNFL) and ganglion cell layer with
corresponding typical visual field (VF)
them; automatically control the function
changes. [4] In the evaluation of glaucoma,
through practice even in the absence of the
RNFL thickness assessment is relevant,
return signal .[6]
because thinning of the RNFL is directly
The purpose of this study is to evaluate the
correlated with loss of ganglion cells, which
efficacy of visual rehabilitation with MP-1
is assumed to be a primary site of
biofeedback
glaucomatous damage.[5]
glaucoma through the study of BCEA.
The management of patients with advanced
Methods
glaucoma presents difficulties. Advanced
We have enrolled 16 patients (9 female and 7
glaucoma is considered to be enough loss of
male), who had come to Department of
vision to produce significant symptoms and
Ophthalmology A. Fiorini Hospital, ‘‘La
functional
Sapienza’’
impairment
that
can
include
in
patients
University
of
with
advanced
Rome,
with
difficulty in performing visual tasks and tiring
advanced open angle glaucoma and we have
easily from those visual tasks. It is for these
examined a total of 20 eyes, from January
reasons that we thought to submit patients
2013 to March 2014. The mean patient age
with
was 69 years old (range: 59–80 years old).
advanced
rehabilitation
with
glaucoma MP-1
to
visual
microperimeter
Were enrolled patients aged between 40 and
(NIDEK Technologies Srl, Padova, Italy)
75 years, with diagnosis of glaucoma by at
biofeedback.
least 10 years, treated with hypotonic therapy.
Through these methods, adopted in various
Patients with angle-closure and secondary
branches of medicine, the patient learns in
glaucoma, previous corneal diseases, uveitis,
successive stages to appreciate the variations
vitreo-retinal interface diseases and retinal
of a bodily function through a system that
detachment were excluded.
measures and converts these in acoustic
The diagnosis of advanced glaucoma was
and/or luminous signals; modify these signals
based on a complete eye examination which
and, therefore, the function connected to
included: biomicroscopic examination of
anterior and posterior segment, visual acuity,
which was converted to logarithm of the
Goldmann
tonometry,
minimum angle of resolution (logMAR) for
gonioscopy with three mirror Goldmann lens,
statistical analyses; near visual acuity was
visual field (VF) examination by Octopus 30-
determined at 30 cm with an appropriate
2
addition.
static
applanation
perimetry,
Tomography
(OCT)
Optical
Coherence
Spectral
Domain
The reading speed for each eye was measured
(Heidelberg HRA-2, TMB module Heidelberg,
by
Germany) with RNFL study and pachimetry.
background (Times New Roman font) at 30
Advanced glaucoma was defined as having
cm of distance with an appropriate addition.
either cup-to-disk ratio ≥ 0.7 or a cup-to-disk
Subjects were asked to read aloud as quickly
ratio asymmetry ≥ 0.2 between adjacent eyes,
as possible without skipping words (the size
with a severely affected eye with best-
of the press corps has been adapted to the
corrected visual acuity below 20/200.
patient's visual acuity and was measured in
Institutional Review Board (IRB) approval
electronic points). The sentences contained
and a written informed consent were obtained
words that occur frequently in Italian and had
from all patients. All procedures adhered to
no punctuation.
the tenets of the Declaration of Helsinki.
Microperimetry
All the patients underwent the same low-
performed
vision rehabilitation protocol which consisted
NIDEK Technologies Srl, Padova, Italy,
of: the assessment of distance and near visual
using
acuity,
threshold test of 4–2 strategy, and a 2° single
reading speed
test
(words/min),
reading
the
black
with
letters
and
fixation
MP-1
automated
fixation
target;
on
a
white
test
were
Microperimeter,
programme,
however,
at
the
fixation test, microperimetry, 10 training
cross
the
sessions with MP-1 biofeedback with the
beginning of the study the size was enlarged
study of BCEA.
to a 3° single cross fixation target when
Best distance spectacle corrected visual acuity
patient was not able to see the 2° single cross
(BCVA) was determined using Snellen chart,
fixation target. Retinal threshold sensitivity
was measured in all eyes using the mire of
Statistical analysis was performed using
Goldmann III (round shape with a white
paired Studentâ&#x20AC;&#x2122;s t-test. p values less than 0.05
background) with stimulus intensity ranging
were considered statistically significant for all
from 0 to 20 dB. Stimulus presentation time
tests because of the preliminary nature of this
was 200 ms. Fixation stability was quantified
study.
by calculating a bivariate contour ellipse area
Results
(BCEA) encompassing 68% of fixation points
We have examined 16 patients (9 female and
based on collected fixation data by the MP-1
7 male), for a total of 20 eyes, with advanced
Microperimeter.
glaucoma from January 2013 to March 2014.
The rehabilitation protocol consisted of 10
The mean patient age was 69 years old (range:
training sessions of 10 minutes for each eye,
59â&#x20AC;&#x201C;80 years old). All partecipants completed
performed once a week using the MP-1
the rehabilitation period. All patients had
biofeedback examination. The patients were
advanced glaucomatous visual field loss, with
asked to move their eyes according to an
a mean deviation (MD) worse than -24 dB,
audio feedback which advised them whether
having only a central or temporal island
they were getting closer to the desired final
remaining in the VF gray scale, and clear
fixation position.
evidence of glaucoma in the fellow eye
At
the
end
of
the
rehabilitation,
the
(manifest as glaucomatous appearing discs
assessment of distant and near visual acuity,
and a glaucomatous VF).
reading
and
Fixation stability, quantified by calculating a
repeated.
BCEA encompassing 68% of fixation points
Microperimetry was repeated with follow-up
based on data collected by the MP-1
function, which automatically retests the
Microperimeter, become from 2.08+0.21 deg2
retinal
to 0.98+0.33 deg2 (p=0.21) and this result was
speed
microperimetry
test, tests
fixation were
sensitivity in exactly the same
locations and under the same conditions as in the previous examination.
statistically significant.
Mean
retinal
sensitivity
became
from
possible resistance point of aqueous humor
4.78+3.39 dB to 8.87+5.44 dB and this result
outflow in primary open angle glaucomatous
was statistically significant (p=0.035).
eyes.
The mean best corrected visual acuity
Measurements of intraocular pressure and
(BCVA) was
standard visual fields are the endpoints
0.76+0.32 logMAR at the
baseline assessment,
generally accepted by the FDA in evaluations
and 0.84+0.60 logMAR at the end of visual
of new therapies for glaucoma. Recently, we
rehabilitation; this result was not statistically
have seen that structural changes (e.g., in the
significant (p=0.29).
optic disc measured by stereophotography)
Reading speed improved from a mean value
predict standard visual field outcomes.[10]
of 24.6+3.2 words/minute at the beginning of the study to 48.9+2.5 words/minute at the end of the training; this result was statistically significant (p=0.037). Discussion
At the early stage of the disease, macular function is mostly spared. However, at the advanced stage, the scotoma threatens to the fixation area becomes particularly important. At present, visual acuity testing, static and
Glaucoma affects more than 60 million
kinetic perimetry are used to monitor macular
people worldwide; more than 10% are
function of glaucoma patients. Visual acuity
consequently legally blind in both eyes.[1]
is a good indicator of foveal function, but it
The World Health Organization predicts that
reveals only one aspect of macular function.
44.7 million people will suffer from primary
Perimetry can show the functioning of
open-angle glaucoma (POAG).[7]
individual retinal locations in the macula, but
Abnormally high intraocular pressure (IOP) is
the number and location of the testing points
related to the development of glaucoma.[8-9].
might not be adequate to detect subtle
Comparative anatomy results suggest that the
changes around the fixation region and in
Schlemmâ&#x20AC;&#x2122;s canal, which connects the
advanced glaucoma reliable test results are
trabecular meshwork and collector canals, is a
difficult to obtain because of unstable fixation.
Advanced glaucoma is considered to be
for reading and usually not the most profitable
strong enough to produce significant loss of
considering retinal sensitivity .[12]
vision and functional impairment that create a
Contestabile, Vingolo, Giorgi, Mezawa et al.
hardship for patients.
[6,13-15] have all proposed different visual
Itâ&#x20AC;&#x2122;s for these reasons that we have tested the
rehabilitation techniques and instruments
efficacy of MP-1 Microperimeter to improve
using biofeedback strategies starting from
the behaviour of fixation and to rehabilitate
basic systems like Accomotrack Vision
patients with advanced glaucoma. Takanori et
Trainer (which is a high- speed infrared
al. investigated fixation behaviour in 39 eyes
optometer which records the vergence of light
with advanced glaucoma using the MP-1
reflected from the retina at a rate of 40 Hz,
Microperimeter and they concluded that the
than converts the signal into an auditory tone
MP-1 is able to illustrate the fixation patterns
which increases in pitch and rate as
in glaucomatous eyes and that patterns are
accommodation decreases; the subject listens
well correlated with retinal sensitivity.[11]
to the tone and thus receives immediate
Biofeedback applied to vision is still being
auditory
studied both in its methodological and
accommodative
physiological aspects. Crossland et al. showed
biofeedback integrated system (IBIS) devices,
that the MP-1 Microperimeter uses cerebral
merging to more complex instruments as the
plasticity and neurosensorial adaptation to the
fundus
central scotoma of patients with macular
(NIDEK Technologies Srl, Padova, Italy).
diseases to improve their visual abilities and
The
more manageable visual aids. Indeed, such
examination allows the ophthalmologist to
patients often develop a new PRL, which can
train the patient to fixate the target with a new
be defined as a discrete retinal area that
PRL. Patients are asked to move their eyes
contains more than 20% of the fixation points
according to an audio feedback which tells
in a location that is considered unfavourable
them whether they are getting closer to a
feedback
related
MP-1
as
status)
MP-1
to or
his/her improved
Microperimeter
Microperimeter
biofeedback
specific
the
limitations: it does not make allowances for
ophthalmologist. Sound perception increases
the typical elliptical nature of fixation
the conscious attention of the patient, thereby
distributions.[23]
facilitating the lock-in of the visual target and
fixation patterns frequently exhibited by
increasing the permanence time of the fixation
people with macular disease.[24-26]
target itself on the retina. This mechanism
cannot differentiate between a subject who
probably
transmission
has good fixation within 2 discrete, yet
between intraretinal neurons as well as
spatially distant, retinal loci and one who has
between the retina and brain, where the
genuinely poor fixation, and it is very poorly
highest degree of stimuli processing takes
related to any parameter of reading.
place, thereby supporting a â&#x20AC;&#x153;remapping
Studies have demonstrated the efficacy of
phenomenonâ&#x20AC;?
of
low-vision rehabilitation by means of MP-1
biofeedback have been performed in the
biofeedback examination in patients with
treatment of ametropia (myopia, astigmatism
different
presbyopia), nystagmus and amblyopia .[15,
demonstrated an improvement in visual acuity,
18-19] Various studies have demonstrated
fixation behaviour, retinal sensitivity and
that
reading speed .[13]
a
retinal
region
facilitates
stimuli
.[16-17]
bivariate
chosen
by
Techniques
contour
ellipse
area
or for the multimodal
macular
disease
and
It
they
(BCEA )can describe the locus of fixation in
Some authors have evaluated the visual
normal and affected individuals.[20-22] The
training biofeedback with Visual Pathfinder
area of this ellipse gives an indication of
(LACE inc.) system in patients with high
fixation
myopia and retinitis pigmentosa.[28-29]
stability,
with
larger
areas
corresponding to poorer fixation stability. The
Various
hypotheses
regarding
the
parameters of both measurements are now
mechanisms of visual function improvement
incorporated within the MP-1 test report. We
after visual training techniques can be put
have chosen to study fixation with BCEA
forth. There could be improvement in ocular
because the Fujii classification has significant
motor control and in 'searching capacity'.
Furthermore, learning to use eccentric fixation
In this study we wanted to demonstrate that it
could be a mechanism contributing to
is possible to apply visual rehabilitation with
amelioration .[29] In particular it is very
MP-1 biofeedback also to patients with
important to note that visual function could be
advanced glaucoma obtaining satisfactory
improved
undergoing
results. In fact, an increased fixation stability
training improve their ability to demonstrate
and retinal sensitivity improve reading speed
their best visual acuity and other visual
and visual efficiency. We also evaluate the
abilities.
utility of BCEA to assess visual function in
Sabel et al. proposed the "residual vision
advanced glaucoma. This bivariate contour
activation theory" of how visual functions can
ellipse area (BCEA) provides a precise
be reactivated and restored.[30]
continuous value for fixation stability, with
The possibility and to what extent vision
smaller values corresponding to more stable
restoration can be achieved is a function of
fixation.[22] In the past decade, reports
the amount of residual tissue and its activation
arising mostly from Germany have suggested
state.
that a specific pattern of visual stimulation
because
Sustained
patients
improvements
require
repetitive stimulation which may take days or
directed to the border between the seeing and
months.
the blind field, Vision Restoration Therapy
Surely a certain role in the determination of
(VRT), can result in expansion of visual fields
the results could be due to subjective
in those with brain or optic nerve injury.[32-
variables such as learning effect, motivation,
33] Romano et al. demonstrated that visual
level of attention, psycho-physical capacities,
restoration therapy (VRT) improves stimulus
kind of environment and influence of the
detection and results in a shift of the position
examiner. Connection between visual acuity,
of the border of the blind field as measured on
central retinal sensitivity and fixation stability
suprathreshold visual field testing. These
has been demonstrated .[31]
results support prior reports and support VRT as a useful rehabilitative intervention for a
proportion of patients with visual field defects
the usefulness of BCEA to achieve better
from retrochiasmatic lesions.[34]
analytical
The possibility and to what extent vision
classification of the fixation pattern using
restoration can be achieved is a function of
microperimetry. It is important to highlight
the amount of residual tissue and its activation
the strict correlation between BCEA fixation
state. Sustained improvements require
values with reading speed. In conclusion, the
repetitive stimulation which may take days or
implementation of BCEA measurement in
months.
MP1 may result in a more accurate evaluation
Our experience with low-vision rehabilitation
of the efficacy of visual rehabilitation and/ or
in patients with advanced glaucoma suggests
medical or surgical treatment in patients with
that it could be possible to improve their
advanced glaucoma.
residual vision, to restore a better visual
Would be desirable to perform studies with a
performance and a much more positive
larger number of patients to confirm the
psychological situation. These results confirm
significance
.
study
and
of
more
the
accurate
data
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