7 d domanico , f verboschi1, em vingolo visual rehabilitation with mp 1 biofeedback in advanced glau

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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