This case report describes a new binocular treatment for amblyopia called antisuppression therapy. The researchers developed a way to measure suppression in amblyopic patients using dichoptic global motion stimuli. They then treated three strabismic amblyopes using prolonged viewing conditions that reduced suppression, allowing information from both eyes to be combined. This led to a strengthening of binocular vision over time. Eventually, the patients could combine information from both eyes under natural viewing conditions. The treatment also improved monocular acuity in the amblyopic eye and established stereoscopic function in all three patients. The findings provide support for a new binocular treatment approach that targets suppression reduction as the first step.
Visual Evoked Potential in Normal and Amblyopic Childreniosrjce
IOSR Journal of Dental and Medical Sciences is one of the speciality Journal in Dental Science and Medical Science published by International Organization of Scientific Research (IOSR). The Journal publishes papers of the highest scientific merit and widest possible scope work in all areas related to medical and dental science. The Journal welcome review articles, leading medical and clinical research articles, technical notes, case reports and others.
Visual Evoked Potential in Normal and Amblyopic Childreniosrjce
IOSR Journal of Dental and Medical Sciences is one of the speciality Journal in Dental Science and Medical Science published by International Organization of Scientific Research (IOSR). The Journal publishes papers of the highest scientific merit and widest possible scope work in all areas related to medical and dental science. The Journal welcome review articles, leading medical and clinical research articles, technical notes, case reports and others.
Binocular interaction in amblyopia and its clinical feasibilityBABLI SHARMA
BINOCULAR INTERACTION ITS ASSOCIATION WITH AMBLYOPIA
Apart from binocular summation, the two eyes can influence each other in at least three ways.
Pupillary diameter. Light falling in one eye affects the diameter of the pupils in both eyes. One can easily see this by looking at a friend's eye while he or she closes the other: when the other eye is open, the pupil of the first eye is small; when the other eye is closed, the pupil of the first eye is large.
Accommodation and vergence. Accommodation is the state of focus of the eye. If one eye is open and the other closed, and one focuses on something close, the accommodation of the closed eye will become the same as that of the open eye. Moreover, the closed eye will tend to converge to point at the object. Accommodation and convergence are linked by a reflex, so that one evokes the other.
Interocular transfer. The state of adaptation of one eye can have a small effect on the state of light adaptation of the other. Aftereffects induced through one eye can be measured through the other.
Singleness of vision
Active Vision Therapy in Management of Amblyopia (healthkura.com)Bikash Sapkota
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/lazy-eye-amblyopia/❤❤
In the request of my viewers, I have compiled my works here in a website. Visit this website (healthkura.com) to freely download this presentation along with other tons of presentations. Some useful links are given here.____Remember___healthkura.com
Active Vision Therapy in Management of Amblyopia
- Pleoptics
- Near activities
- Active stimulation therapy using CAM vision stimulator
- Syntonic phototherapy
- Role of perceptual learning
- Binocular stimulation
- Software-based active treatments
- Exposure to dark
- Pharmacological Therapy
Background: Strabismic amblyopia is characterized by an imbalance of the sensorial and motor system. Differences between both
eyes due to squinting during 1st months of life can originate an entire fovea fixation and ARC, which is a binocular condition generated
by the absence of a correct bi-foveal fixation [2]. Accommodative esotropia usually presents between 2 and 4 years of age with an
increase in accommodative needs and is directly linked to the amount of hypermetropia [9]. Although patching remains the gold
standard therapy of amblyopia, several new treatment options have emerged over the years. These include refractive adaptation,
atropine penalization, and several binocular activities with varying success rates [10].
Case Report: 6-year-old male presented with complaints of inward deviation, and blurring of vision for distance and near. A proper
squint evaluation was performed to determine the presence of the type of squint. Accommodative esotropia with amblyopia in one
eye was reported. Synoptophorehaidinger brushes were recommended for foveal stimulation for the amblyopic eye followed by
patching. The patient reported good compliance and significant vision improvement in the amblyopic eye and no longer blur and
deviation with glasses were observed.
Conclusion: Accommodative esotropia with amblyopia showed substantial improvement with the help of Haidinger brushes in the
amblyopic eye. A combination of patching and Haidinger brushes is an efficacious approach for achieving an improvement in visual
acuity and binocular function in strabismic amblyopia.
Keywords: Accommodative Esotropia; Strabismic Amblyopia; Haidinger Brushes; Synoptophore
Strabismus is a condition in which the eyes do not properly align with each other when looking at an object. The eye which is focused on an object can alternate. The condition may be present occasionally or constantly.If present during a large part of childhood, it may result in amblyopia or loss of depth perception. If onset is during adulthood, it is more likely to result in double vision.
Amblyopia is characterized by several functional abnormalities in spatial vision, including reductions in visual acuity, contrast sensitivity function, and vernier acuity, as well as spatial distortion, abnormal spatial interactions, and impaired contour detection. In addition, individuals with amblyopia suffer from binocular abnormalities such as impaired stereoacuity (stereoscopic acuity) and abnormal binocular summation
Those with strabismic amblyopia tend to show ocular motion deficits when reading, even when they use the nonamblyopic eye. In particular, they tend to make more saccades per line than persons with normal stereo vision, and to have a reduced reading speed.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
2. cortex functionally monocular. The consequence is that amblyopia
is an intrinsically binocular problem and not the monocular prob-
lem on which current patching treatment is predicated. Thought
of in this way, the binocular problem involving suppression should
be tackled at the very outset if one is to achieve a good binocular
outcome as opposed to hoping binocular vision will be regained
simply as a consequence of acuity recovery in the amblyopic eye,
which is the current approach and which is often not found to be
the case.2
Recently, we developed a novel way of quantifying suppression.6
We showed, under a wide variety of conditions, when the signal to
the fellow fixing eye is reduced in strength (in this context this is
the contrast of the stimuli), strabismic amblyopes can combine
information between their two eyes, as normal patients do. Thus,
our current notion of suppression is that it reduced the efficiency
with which the signal seen by the amblyopic eye is transduced. The
extent to which the signal strength to the fellow fixing eye needs to
be reduced allows one to quantify the degree of suppression. Here,
we report the results of three case studies where continual and
intensive measurement of the degree of suppression leads, in itself,
to a reduction of the degree of suppression until it is eliminated. In
other words, providing artificial viewing conditions under which
binocular combination can take place results in a strengthening of
binocular vision, so that it can occur under a wider variety of
interocular viewing conditions. Eventually, binocular combina-
tion can occur under more natural viewing conditions when the
eyes view objects of the same physical contrast. This finding pro-
vides the basis for a new binocularly based treatment of amblyopia
in which the suppressive imbalance is measured and treated as a
first step. We found that in many cases, the reduction in suppres-
sion led not only to a reestablishment of stereoscopic function but
also to a reduction in the monocular acuity deficit, attesting to the
primal importance of suppression in the amblyopic syndrome.
METHODS
Observers
We discuss the case results of three adult strabismic amblyopes
who underwent antisuppression therapy. Refraction in all observ-
ers was undertaken, and vision was corrected to best visual acuity.
The “Declaration of Helsinki” was followed and informed consent
was obtained from all observers before data collection.
Dichoptic Global Motion
The Measurement of Suppression
To measure the ability of amblyopic observers to binocularly
combine motion information, we used random dot kinemato-
grams and a coherence motion discrimination task (see Ref. 6 for
details). These stimuli are constructed of two populations of mov-
ing dots. The “signal” population consists of dots that all move in
the same direction, termed the “coherent” direction. Conversely,
the “noise” population has no common motion direction because
all the dots move in random directions. The ratio of signal to noise
dots required to determine the coherent motion direction is called
the motion coherence threshold. Therefore, by using these stimuli
with signal and noise separated dichoptically, one can assess the
degree to which underlying mechanisms combine information
from two eyes.
We have previously used this approach to study binocular inter-
actions in normals8
and strabismic amblyopes,6
and the test has a
high test/retest reliability (r ϭ 0.89; p Ͻ 0.0001). Performance
(that is the signal magnitude required to reach the threshold crite-
rion) was quantified by changing the signal to noise ratio in the
random dot kinematogram. The extent to which information was
combined binocularly was quantified by only allowing one eye to
see the signal and the other eye to see the noise (Fig. 1). In a
binocularly normal individual, the noise seen by one eye makes the
detection of the motion direction of the signal elements seen by the
other eye more difficult. However, it does not matter which eye
sees the signal and which sees the noise. There is a “dichoptic
balance” in the threshold performance. In amblyopes with sup-
pression, it matters which eye sees the signal and which eye sees
the noise. In the most extreme case, if the fellow fixing eye sees the
signal and the amblyopic eye sees the noise, then owing to the
suppression of the amblyopic eye by the fellow fixing eye, perfor-
mance will be at ceiling. On the other hand, if the amblyopic eye
sees the signal and the fellow fixing eye sees the noise, then the
performance will be at chance. Thus, one would expect there to be
an imbalance in the dichoptic thresholds because of suppression.
By suitably imbalancing the strength of the signals seen by the
fellow fixing eye (be it signal or noise), we found that balanced
dichoptic performance could be obtained, reflecting the fact that
the information from the two eyes was being combined binocu-
larly. In other words, imbalancing the input to the amblyopic
binocular visual system can result in a balanced output, namely
normal binocular combination. The extent of the signal imbalance
needed to achieve this balanced performance provides a measure of
the degree of suppression.
The dichoptic stimuli were produced using a large, eight-mirror
stereoscope to allow signal and noise dots to be presented sepa-
rately to each eye, and thresholds were measured using a standard
up/down staircase procedures. The testing field was circular with a
diameter of 7°, having an outer peripheral fusion frame that was
used to ensure correct alignment of dichoptic images in the case
where strong suppression prevented the central nonius markers
from being used. This was the case for the first strabismic amblyope
(case 1).
Stimulus
Visual Acuity and Stereo Acuity
Visual acuity was measured with a Snellen letter chart at 6 m,
and stereo acuity using the preschool Randot test at 30-cm viewing
distance.
RESULTS
Case 1
Case 1, a 44-year-old man, who was an emmetrope, presented
with a constant 20° left esotropia and grossly reduced acuity (20/
400) in the left eye that could not be improved with a refractive
correction. He had a history of strabismic amblyopia from the age
of 4 years, when the strabismus was first detected but had not
698 Binocular Interactions in Amblyopia—Hess et al.
Optometry and Vision Science, Vol. 87, No. 9, September 2010
3. undertaken any patching and had not had surgery. He did not
show fusion on the Worth 4 dot test (distance and near) and had
no measurable stereopsis on the preschool Randot test (near). Our
measurement of his suppression using our dichoptic global motion
stimulus is shown in Fig. 2A. Here, we are plotting the dichoptic
threshold ratio, which is the ratio of the performance when the
amblyopic eye sees the noise and the fellow eye the signal compared
with vice versa. In a binocularly normal observer, it does not matter
whether the right eye sees the signal and the left eye sees the noise
or vice versa because the information from the two eyes is com-
bined and the binocular signal to noise ratio is the same in these
two situations. In this case, we would expect the dichoptic thresh-
old ratio as expressed in Fig. 1A, B to be at unity. The extent to
which the dichoptic ratio is above unity signifies that there is an
imbalance in the combination of binocular information, and in the
case of strabismus, this is because of suppression. We quantify
the degree of suppression by seeing how much we have to offset the
contrast (i.e., reduce it in the fellow fixing eye) to establish equal
performance (i.e., a dichoptic threshold ratio of unity). The ab-
scissa is the contrast ratio of the stimulus (be it signal or noise) seen
by each eye. The contrast of his fellow fixing eye had to be reduced
by a factor of ϳ8 before there was evidence that information was
being combined between his two eyes (the balance point is indicated
by the interocular contrast ratio that corresponds to a dichoptic
threshold ratio of unity, i.e., x axis intercept). This indicates a strong
level of suppression exerted on the amblyopic by the fixing eye under
binocular viewing conditions.
This subject came in for 3 weeks, (4 days a week, average of 350
threshold measurements per week) repeating this measurement of
the balance point under the assumption that by providing condi-
tions over an extended time where the suppression by the fixing eye
is reduced (by reducing the contrast of the signal and noise seen by
the fixing eye) that this would lead to a strengthening of the bin-
ocular connections that underlay the combination of left and right
eye information. Summary measurements of the balance point
after the first (dashed line) and last (filled symbols) week of training
are shown in Fig. 2B. It is clear that after a substantial amount of
binocular training, the degree of suppression is reduced, as re-
flected in the fact that the contrast of stimuli shown to the fixing
eye now needed to be reduced to a much lesser extent. In this case,
the balance point (i.e., the contrast ratio at which the dichoptic
threshold ratio was unity) only changed a little (i.e., from a contrast
ratio of eight before treatment to one of five after treatment);
however, large changes occurred in the extent to which the fellow
fixing eye’s signal needed to be reduced in contrast for binocular
combination to take place (i.e., for stimuli of equal contrast, the
FIGURE 1.
Schematic presentation of the random dot kinematogram shown to each eye during dichoptic viewing. Black arrows show the signal dots schematically,
which were moving, in the same direction (up vs. down) within a trial. White arrows represent the noise dots schematically, which were moving in
random directions. In different trials, signal dots were shown to the fixing eye and noise dots to the fellow amblyopic eye and vice versa. The ratio of
the thresholds obtained for these two types of dichoptic presentations was computed as the dichoptic threshold ratio.
Binocular Interactions in Amblyopia—Hess et al. 699
Optometry and Vision Science, Vol. 87, No. 9, September 2010
4. FIGURE 2.
Results are shown for Case 1 in terms of (A) the initial measurement of suppression (see text), (B) how this changed with prolonged artificial binocular
viewing, (C) how the dichoptic threshold for both eyes changed with prolonged artificial binocular viewing, (D) how visual acuity changed for each
eye as a function of the training, and (E) the reinstating of stereopsis after training.
700 Binocular Interactions in Amblyopia—Hess et al.
Optometry and Vision Science, Vol. 87, No. 9, September 2010
5. dichoptic threshold ratio was 11 before treatment, and three after
treatment).The fact that it took 1 or 2 weeks before improvements
were seen was probably because of the limited treatment duration.
Another way of quantifying the extent to which suppression is
reduced, and as a consequence binocular combination is strength-
ened, is to compare results where each eye receives stimuli of the
same contrast (conditions where suppression is maximal). This is
relevant to everyday viewing where the physical contrast of stimuli
impinging on the retinae is of identical contrast. This corresponds
to the condition where dichoptic motion thresholds (e.g., Fig. 2A,
B) are most different (leftmost data in these figures, i.e., an intero-
cular contrast ratio of unity) owing to the strong suppression that
occurs from the fellow fixing eye to the amblyopic eye under these
conditions. In Fig. 2C, we plot the dichoptic motion thresholds of
each eye (from which the ratios were computed for Fig. 2A, B) as a
function of the weeks of training. Our binocular training regime
improves the dichoptic motion threshold of the amblyopic eye
(i.e., when the amblyopic eye sees the signal and the fixing eye the
noise) although having much less impact on the dichoptic motion
thresholds of the fixing eye (i.e., when the fixing eye views the
signal and the amblyopic eye the noise). Over time, the threshold
of the amblyopic eye approaches that of the fixing eye (i.e., the ratio
of the dichoptic thresholds is approaching unity in Fig. 2A, B).
What this means is that, over time, suppression is being reduced
and the two eyes of this strabismic amblyope are now successfully
combining information of comparable contrasts between the two
eyes. The improved binocular combination that results was re-
flected in the establishment of stereoscopic function. Stereoscopic
sensitivity was limited to 200 arc secs but was present for the first
time (Fig. 2E).
We were surprised to find that monocular acuity of the am-
blyopic eye improved as a result of our antisuppression therapy.
These results are shown in Fig. 2D where Snellen line letter
acuity is plotted against the period of training. A significant
improvement accompanies the reduction of suppression even in
this adult amblyope.
Case 2
Case 2 was a 45-year-old man who had a history of anisome-
tropic amblyopia [R, Ϫ1.75 diopter (D)/ϩ0.50 ϫ 90°; L, ϩ1.25
D] which had been first detected at the age of 11 years and treated
with a mixture of patching for 1 to 2 years and refractive correction
at the age of 11 years. No surgery had been undertaken. He pre-
sented with a 3-D anisometropia, a 6° constant esotropia (also
detected at the age of 11 years), a mild degree of amblyopia (20/
63), no fusion on the Worth 4 dot test, and no measurable stere-
opsis at near.
Using our global motion measurement of suppression, we found
a degree of suppression that could be nullified when the contrast of
the stimuli viewed by the fixing eye were reduced by a factor of 4
(Fig. 3A).
Over the antisuppression treatment period of 5 weeks (4 days a
week, average of 350 threshold measurements per week), there was
a steady change in the degree of suppression exerted by the fixing
eye. This is reflected in a change in the derived balance point (i.e.,
the interocular contrast ratio where the dichoptic threshold ratio
between the fixing and amblyopic eyes is unity, x axis intercept in
Fig. 3B) or by the progressive improvement in the dichoptic mo-
tion threshold for the amblyopic eye for stimuli of equal contrasts
in the two eyes (Fig. 3C). Monocular acuity improved in the am-
blyopic eye from 20/63 to 20/30 (Fig. 3D), and stereopsis was
established with an acuity of 20 arc secs (Fig. 3E).
Case 3
Case 3 was a 33-year-old woman with a history of strabismic
amblyopia (R, Ϫ1.00 D; L, Ϫ0.50 D) having been first detected at
the age of 5 years. Two years of constant patching was undertaken,
but there had been no surgical intervention (visual acuity at the end
of this patching was not available). She presented with a small but
bilaterally equivalent amount of myopia, a small angle (4°) con-
stant esotropia with intermittent fusion on the Worth 4 dot (dis-
tance and near) test but no measurable stereopsis (near). The acuity
in the deviating eye was 20/80. The measurement of suppression
using the balance point determination with the dichoptic motion
stimulus showed a mild suppression by the fixing eye that could
only be neutralized by reducing the contrast in the fellow fixing eye
by a factor of 3 (Fig. 4A).
During a period of 5-week training (3 days a week, average of
100 threshold measurements per week), using our antisuppression
therapy, the degree of suppression gradually disappeared (indi-
cated by a dichoptic ratio of 1 for equal interocular contrasts in Fig.
4B). Another reflection of this reduction in suppression is the
improvement that occurred in her dichoptic motion thresholds for
her amblyopic eye (signal to amblyopic eye, noise over the training
period). Stereopsis (near) was established with an acuity of 30 arc
secs (Fig. 4E), and monocular acuity in the amblyopic eye im-
proved from 20/80 to 20/25 (Fig. 4D).
DISCUSSION
We describe a new quantitative method for the clinical measure-
ment of suppression, something that is done in either a binary
fashion (i.e., worth 4 dot test) or using methods that are coarse (i.e.,
the Sbisa Bar) or uncalibrated (i.e., reducing illumination for one
eye on the synoptophore) in the clinic at present. The method is
based on a signal to noise approach but applied within the context
of dichoptic stimulation. This allowed us to demonstrate, for the
first time, that threshold and suprathreshold information can be
combined between the eyes of strabismic amblyopes under suit-
able, albeit artificial, viewing conditions.5–7,9
Suppression is a well-
known clinical entity, but it is rarely measured quantitatively and
rarely used to direct the treatment approach. We believe this is
unfortunate because the current animal3,4,10,11
and human5,6
research on amblyopia suggests that it is primarily a binocular
problem with suppression being the key feature. We strongly rec-
ommend that suppression is measured in a quantitative way along
the lines suggested here.
Furthermore, we show here, for three subjects, that intensive
training using this suppression measurement approach leads to a
progressive strengthening of binocular vision in strabismic am-
blyopes such that they can eventually operate under natural view-
ing conditions where the left and right image contrast is equal. We
found this to be the case in 8/10 amblyopes tested so far, and it
should be emphasized that all subjects were adult amblyopes well
Binocular Interactions in Amblyopia—Hess et al. 701
Optometry and Vision Science, Vol. 87, No. 9, September 2010
6. FIGURE 3.
Results are shown for case 2 in terms of (A) the initial measurement of suppression (see text), (B) how this changed with prolonged artificial binocular
viewing, (C) how the dichoptic threshold for both eyes changed with prolonged artificial binocular viewing, (D) how visual acuity changed for each
eye as a function of the training, and (E) the reinstating of stereopsis after training.
702 Binocular Interactions in Amblyopia—Hess et al.
Optometry and Vision Science, Vol. 87, No. 9, September 2010
7. FIGURE 4.
Results are shown for case 3 in terms of (A) the initial measurement of suppression (see text), (B) how this changed with prolonged artificial binocular
viewing, (C) how the dichoptic threshold for both eyes changed with prolonged artificial binocular viewing, (D) how visual acuity changed for each
eye as a function of the training, and (E) the reinstating of stereopsis after training.
Binocular Interactions in Amblyopia—Hess et al. 703
Optometry and Vision Science, Vol. 87, No. 9, September 2010
8. beyond the accepted “critical period” for patching therapy.1
Con-
current with this improvement in the efficacy of binocular combi-
nation, we also found that stereopsis in all three cases presented
here, and in a majority of cases studied so far, was established and
the monocular acuity also improved. These improvements were
significant, stable, and in some cases large.
ACKNOWLEDGMENTS
This study is supported by a CIHR grant MOP 53346 (to RFH).
Received February 23, 2010; accepted April 29, 2010.
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Robert F. Hess
687 Pine Avenue West (H4-14)
Montreal, Quebec, Canada PQ H3A 1A1
e-mail: robert.hess@mcgill.ca
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Optometry and Vision Science, Vol. 87, No. 9, September 2010