This document discusses ocular motor functions including eye movements and their purposes. It explains that eye movements serve to keep visual images stable on the retina, change the angle of gaze, and prevent image fading. Specific eye movements like saccades, pursuits, and vergence are involved in these functions. The document also discusses the neural control of eye movements including the pulse-step theory and afferent and efferent systems that provide feedback and signals to move the eyes.
Ophthalmic Prisms: Prismatic Effects and DecentrationRabindraAdhikary
Ophthalmic Prisms: Prismatic Effects and Decentration
here we discuss about the ophthalmic prisms, the prismatic effects as caused by the decentration( moving the optical center away from the visual axis)
Ophthalmic Prisms: Prismatic Effects and DecentrationRabindraAdhikary
Ophthalmic Prisms: Prismatic Effects and Decentration
here we discuss about the ophthalmic prisms, the prismatic effects as caused by the decentration( moving the optical center away from the visual axis)
Presentation containing information about all types of absorptive lenses its manufacturing, uses, advantages and disadvantages and some information about lens coatings.
Presentation containing information about all types of absorptive lenses its manufacturing, uses, advantages and disadvantages and some information about lens coatings.
The presentation includes physiological mechanism of different functional classes of eye movements such as horizontal & vertical eye movements, saccades, persuits, vestibuloocular reflex, Bell's phenomenon and it also includes different disorders that causes abnormal supranuclear eye movements e.g. skew deviation, Perinaud syndrome, INO.
Role of various systems to maintain balance.
Role of sensory systems-vision,proprioceptors,vestibular
Role of Musculoskeletal system
Biomechanics in balance
Contextual factors in balance
Role of nervous system
Strategies-ankle, hip,stepping
Neuro anatomy and physiology of masticatory system/certified fixed orthodonti...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
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Medicines Used for Glaucoma Management _Optom LectureGauriSShrestha
the most commonly prescribe treatment for glucoma is eye drops. These medicine decreases IOP to the level that prevents damage to the optic nerve by either decrease acqueous secretion from the ciliary body or facilitating acqueous drainage through the trabecular or uveoscleral outflow systems. This presentation outlines the principal eye medicine currently used in ophthalmic practice.
Ocular steroids-Dexamethasone, Betamethasone, Prednisolone and FlurometholoneGauriSShrestha
Corticosteroids are secreted by the adrenal cortex.
Adrenocorticotrophic hormone(ACTH) stimulates the adrenal cortex to produce corticosteroids.
Types of adrenal cortex-related steroids are glucocorticoids and mineralocorticoids. Corticosteroids have anti-inflammatory and immunosuppressive effects
NSAIDs are analgesic, antipyretic and anti-inflammatory drugs.
Non-narcotic, non-opioid, aspirin-like drugs
Primarily, acts on peripheral pain mechanism and do not depress the central nervous system
Some protective role against cancer and cardiovascular diseases (e.g., aspirin, antithrombotic effects)
Accounts for 5% of all drugs prescribe globally
30 million people consume NSAIDs every day
Available over the counter medicine in most countries
Ocular anti-infective agents: Antibiotics, Antivirals and antifungalsGauriSShrestha
Anti-infective agents are effective against a variety of infections (e.g., virus, rickettsiae, bacteria, fungi and protozoa) and cause competitive inhibition of a biochemical process of pathogens. Minimum inhibitory concentration (MICs) are often used for common anti-infective drugs. In the eye, route of drug administration is determined by the locus of infection. However, this ppt covers mostly topical and common antibacterial, antiviral and antifungal medicines.
Pediatric refraction is one of the challenging areas of optometry practice. I am so glad to share some of the important aspect of pediatric refraction.
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
Integrating Ayurveda into Parkinson’s Management: A Holistic ApproachAyurveda ForAll
Explore the benefits of combining Ayurveda with conventional Parkinson's treatments. Learn how a holistic approach can manage symptoms, enhance well-being, and balance body energies. Discover the steps to safely integrate Ayurvedic practices into your Parkinson’s care plan, including expert guidance on diet, herbal remedies, and lifestyle modifications.
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.
Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
MIP 201T & MPH 202T
ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
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
ABDOMINAL TRAUMA in pediatrics part one.drhasanrajab
Abdominal trauma in pediatrics refers to injuries or damage to the abdominal organs in children. It can occur due to various causes such as falls, motor vehicle accidents, sports-related injuries, and physical abuse. Children are more vulnerable to abdominal trauma due to their unique anatomical and physiological characteristics. Signs and symptoms include abdominal pain, tenderness, distension, vomiting, and signs of shock. Diagnosis involves physical examination, imaging studies, and laboratory tests. Management depends on the severity and may involve conservative treatment or surgical intervention. Prevention is crucial in reducing the incidence of abdominal trauma in children.
Gaze shifting & gaze holding ocular motor functions
1. Gaze shifting & Gaze
holding Ocular motor
functions
Gauri S. Shrestha, M.optom, FIACLE
2. What do Eye Movements Do?
Keep visual images relatively stable on the retina
Change the angle of gaze
Prevent the fading of retinal images
Gauri S. Shrestha, M.optom
3. Keeping Visual Images Stable
Prevents retinal slip which leads to motion smear
5 deg/sec can cause motion smear
Example: head movement
Motion Smear causes blur and the inability to accurately
judge object location in space
Eye movements used to prevent motion smear
Vestibular Ocular Reflex (VOR)
Optokinetic Nystagmus (OKN)
Gauri S. Shrestha, M.optom
4. Change the Angle of Gaze
Align fovea with the object of interest
Eye movements used to change gaze angle
Saccades
Pursuits
Vergence
Gauri S. Shrestha, M.optom
5. Prevent Image Fading
Perfectly stabilized images fade
Troxler’s Effect
Eye Movements used to prevent image fade
Drifts
Tremors
Microsaccades
Miniature ocular movements that constantly occur
Gauri S. Shrestha, M.optom
6. Eye Movement Development
From birth and continues to develop
VOR, OKN
From birth and continues to develop
Saccadic movements
From 6-8 weeks and continues to develop
Pursuit movements
From 3 months and continues to develop
Vergence, accommodation
BINOCULAR VISION
Gauri S. Shrestha, M.optom
7. How does the eye move?
The eye is tightly packed in the orbit
2 forces must be overcome
Viscous drag of the orbit
Elastic restoring forces of the orbital tissues
(primary resting position)
2 types of neural activity required to overcome
these forces
Gauri S. Shrestha, M.optom
8. Neural Activity Required
Velocity (pulse) Signal
Phasic increase in neural activity allowing the
EOM to move quickly
Overcomes the viscous drag of the orbit
Position (step) Signal
Sustained increase in neural activity allowing the
eye to maintain the eye at the new position
Overcomes the elastic restoring forces of the
orbital tissues
Gauri S. Shrestha, M.optom
9. Velocity and Position Signals
Without pulse (velocity), eye movement is slow
Without step (position), eccentric eye position
cannot be maintained
Pulse and step signals must match for accurate eye
movements and steady fixation
How do we achieve this?
Gauri S. Shrestha, M.optom
10. Neural Integration
The brain converts the pulse (velocity) signal into
the step (position) signal
What happens if the system fails?
Eye is carried to new position, but drifts back to the
central position
Causes nystagmus (jerky eye movements)
Gauri S. Shrestha, M.optom
11. Motor Plasticity
Eye movements can undergo adaptation changes
When a patient receives new glasses
Larger movements needed for plus lenses
Cerebellum has important role in plasticity
Flocculus and nodulus
Dorsal vermis
Gauri S. Shrestha, M.optom
13. What is Needed for Accurate Eye Movements
The brain needs to know where the eye is located with
respect to the head and orbit
THE AFFERENT SYSTEM
The brain needs to know where and by how much to move
the eye
THE EFFERENT SYSTEM
Clinical Application: Disorders can cause the inability to
accurately judge visual space
Inaccurate ‘positional sense’ in targeting task
Gauri S. Shrestha, M.optom
14. The Afferent System
Provides information about eye position to the
brain
How is this achieved?
Two sources (subsystems)
Proprioception
Efference copy/Corollary discharge
Gauri S. Shrestha, M.optom
15. Afferent System-Proprioception
Includes Muscle Spindles in the human EOM that
respond to stretch
Includes the Palisade Tendon Organ in the human
EOM that responds to tension
These signals are sent to the brain through the
trigeminal nerve
Gauri S. Shrestha, M.optom
16. The Afferent System-Efference Copy
AKA: Corollary Discharge
This is a ‘copy’ of the motor signal to move the
eye that is sent back to the brain
Anatomical origin: unknown
Also involved in distinguishing between real
motion or self motion
Gauri S. Shrestha, M.optom
17. The Efferent System
Provides brain with information about how much
and where to move the eye
Neural information from this system provides
innervation to the ocular motor nuclei to move
the EOM
Gauri S. Shrestha, M.optom
18. Innervation of the EOMs
Oculomotor (Cranial Nerve 3)
MR, SR, IR, IO
Trochlear (Cranial Nerve 4)
SO
Abducens (Cranial Nerve 6)
LR
Gauri S. Shrestha, M.optom
19. Review of these systems
Afferent System
Proprioception
Corollary Discharge or Efference Copy
Efferent System
Sends pulse and step neural signals to the EOM
Gauri S. Shrestha, M.optom
20. The EOM Fibers
Two Major Function
Move the eyes (quickly or slowly)
Change eye position
Keep the eyes relatively stationary
Maintain new eye position
Gauri S. Shrestha, M.optom
21. Physiological Types of Fibers
Twitch Fibers (burst)
All or none action potential
Non-Twitch Fibers (tonic)
Graded contractions
Few fibers are a combination
Gauri S. Shrestha, M.optom
22. Twitch Fibers (Burst)
All or None response
Fast-fatiguing fibers
Known as global fibers
Fibers that are closer to the eyeball
Good for rapidly moving the eye to a new position
Gauri S. Shrestha, M.optom
23. Non-Twitch Fibers (step)
Receive the step signal
Graded contraction
High oxidative capacity
Known as orbital fibers
Fibers that are closer to the orbit
Good for maintaining the new eye position
Gauri S. Shrestha, M.optom
26. Actions of EOMs
From Primary Position
Primary Secondary Tertiary
MR Adduction
LR Abduction
IR Depression Extorsion Adduction
SR Elevation Intorsion Adduction
IO Extortion Elevation Abduction
SO Intorsion Depression Abduction
Gauri S. Shrestha, M.optom
27. Five movement subsystems:
1. Saccadic systems
2. Pursuit systems
3. Vestibulo-ocular reflex
4. Optokinetic reflex
5. Vergence
Gauri S. Shrestha, M.optom
28. Saccadic systems
Saccade named after the French
word describing the rapid turning of
a horse's head
Saccades are very fast yoked eye
movements that have a variety of
function
Speed of saccade – 400-700/s
Saccades produce the quick phase
of vestibular & OKN to avoid
turning the eyes to their mechanical
limitations
Saccades also occur withS.head M.optom
Gauri Shrestha,
movements.
29. Saccadic systems
∀ Undershoot or overshoot during saccades is corrected by
micro saccades or glissade
∀ Saccadic waltz (pulse-slide-step) called glissade (pulse) &
tonic (step) innervations of the saccade
∀ Saccade in neonates is inaccurate . Developed by 1 yr.
∀ Saccade respond very quickly because of their burst or
pulse innervations
∀ Saccadic system involves pulse step mechanism.
∀ Burst of electrical activity is required to move the eye to
the desired position-pulse
Gauri S. Shrestha, M.optom
30. Saccadic systems
∀ After pulse, further energy required to maintain the eye in
desired position & counter elastic recoil –step
∀ Speed of saccade is greatest midway between 1/3 &
halfway of saccade movement -max. Velocity peak (MVP)
∀ Larger the saccade greater the MVP
Gauri S. Shrestha, M.optom
31. Pulse –Step theory
∀ Pulse –step theory is due to 3 groups of neuron.
∀ Burst neuron
∀ Cause rapid electrical discharge with rapid acceleration
medium
∀ At the end stage of the saccade inhibitory burst neuron
stimulate antagonist muscle to stop the movement.
Pause neuron
∀ Inhibit firing of burst neuron until initiation of the saccade
∀ Its activity is suspended immediately after the start of the
saccade
Gauri S. Shrestha, M.optom
33. Pulse –Step theory
Tonic neuron
∀ Responsible for maintaining muscle tone
∀ Its activity increase after saccade to maintain gaze
position represents the step
Gauri S. Shrestha, M.optom
34. Pulse –Step theory
∀ Saccade are regulated by Neural integraters (NI).
NI converts velocity command into appropriate
position command – step (pulse step mechanism)
i.e. pulse is integrated to produce steps.
∀ The pulse innervation produced by the burst cell,
controls the velocity of the saccade and the step of
innervation produced by tonic cell, controls the
final position of the eye upon completion of the
saccade.
Gauri S. Shrestha, M.optom
35. Anatomical pathways
Frontal eye field (frontal cortex,
area 8)-->
ant. Limb of internal capsule-- >
decussate in lower midbrain-- >
synapse at horizontal gaze center
(PPRF-Paramedian Pontine
Reticular Formation) -- >
CN VI nucleus-->
motor neurons to LR and
Interneurons to MR
subnucleus(CNIII)
Gauri S. Shrestha, M.optom
36. Anatomical pathways
Motor neurons of MR i.e. right
frontal cortex initiates saccades to
left
Also superior colliculus initiate
the contralateral saccade in
response to novel visual stimuli
Cerebellum also plays a major role
in controlling saccadic pulse size
and so aids in co-ordinated eye
movements.
Gauri S. Shrestha, M.optom
37. Smooth pursuit
Tracking or following movement
∀ Much slower than saccadic with maximum speed
at 400/s, if speed higher than that??
∀ Latency- 100- 125msec
∀ Slow eye movements are also generated by
vestibules
In neonates tracking usually accompanied by
series of saccades. Full development by 3-4
months of age
Gauri S. Shrestha, M.optom
38. Smooth pursuit
Functions
∀ Cancellation of VOR during head tracking foveas
∀ Cancellation of OKN during fixation and tracking
∀ Foveate moving isolate targets (stabilizes moving objects
on retina when background.
Gauri S. Shrestha, M.optom
39. Smooth pursuit
Control of pursuit
∀ Parietal cortex (medial,
temporal..)
∀ MT, MST
∀ Horizontal pursuit is initiated by
ipsilateral occipito-paritetal
cortex--> PPRF--> motor
neurons of LR & MR i.e. left
occipital cortex is responsible for
left pursuit
∀ Vertical pursuit originate in
occipito parietal region,
interstitial nucleus of cajal
(INC)--> CN IV, III Gauri S. Shrestha, M.optom
40. Vestibulo-ocular reflex (VOR)
∀ The first class of stabilizing eye movement that
components for brief head and body rotation
∀ Generates slow eye movements in response to head
movement maintaining steady eye position
∀ Semicircular canals of the vestibulo labyrinth
signals how fast the head is moving and oculomotor
system responds to this signal by rotating the eyes
in an equal and opposite velocity.
Gauri S. Shrestha, M.optom
41. Vestibulo-ocular reflex (VOR)
∀ Stabilizes the eyes relative to the external world and
keep visual images fixed on the retina
∀ Works in total darkness responds to acceleration and
deceleration but not to constant velocity
∀ Control initial image stabilization
∀ Otoliths (saccula) compensates for head tilt movement that
cause torsional eye movement
∀ Proprio-receptors in neck muscles also contribute towards
VOR
Gauri S. Shrestha, M.optom
42. Vestibulo-ocular reflex (VOR)
∀ Can be tested with Doll head movement and
inducing vestibular nystagmus using swinging
baby test or caloric test
∀ Caloric test --> Pt head inclined at 600 so that
Horizontal Semicircular canals lies vertically-->
∀ COWS (Cold water – fast phase of nystagmus
towards opposite labyrinth, warm water – fast
phase towards same labyrinths)
Gauri S. Shrestha, M.optom
44. Optokinetic Reflex (OKN)
∀ 2nd ocular stabilization system that responds to
currents of image motion
∀ Also referred as railway / parade nystagmus
∀ OKN supplements VOR in several ways
∀ OKN responds to constant velocity
∀ Both OKN & VOR exhibit jerk nystagmus
(following movement and then saccade)
Gauri S. Shrestha, M.optom
45. Optokinetic Reflex (OKN)
∀ Active OKN or pursuing, the phase follows target
towards the periphery away from primary gaze
∀ Passive OKN or starring, the fast phase (saccade)
to where the target is emerging from and then has
a slow phase back to primary gaze.
∀ OKN is responsible to large fields 20- 500
∀ Max. Velocity rarely exceeds 500/sec usually in
close to the stimulus velocity below 300/sec
Gauri S. Shrestha, M.optom
46. Optokinetic Reflex (OKN)
∀ Can be demonstrated with OKN drum, look at the
stripes, pursuit and saccades occurs --> refers
OKN
∀ Slow target velocities --> good correspondence
∀ >30-1000/s velocities- eye movement lags behind
target movement
∀ Beyond 1000/s – OKN can't be demonstrated
Gauri S. Shrestha, M.optom
47. Optokinetic Reflex (OKN)
∀ OKN development in an infant from the sub-
cortical crossed input—stimulates a nasal ward
slow phase of OKN (Both eyes move smoothly
towards covered eye)
∀ After 3 months, infants cortical projection
predominate and horizontal OKN responds to both
temporal ward and nasal ward image motion.
∀ Vertical OKN can also tested
Gauri S. Shrestha, M.optom
48. Vergence
∀ Disjunctive or Vergence eye movements are movements of
the eyes in opposite direction
∀ They can be horizontal , vertical and cyclo
∀ Vergence doesn't appear in animals with laterally placed
eyes
∀ Units of measurement- degrees, prism Diopters, meter
angle
∀ Maddox classification of Vergence- tonic, proximal,
disparity & accommodative
∀ Stimuli- retinal disparity, diplopia, accommodation,
convergence
Gauri S. Shrestha, M.optom
50. Vergence
∀ Development – in full term from neonates but un-
coordinated- accurate convergence developed by 2-3
months of age
∀ Slower than saccades
∀ Supra nuclear control of Vergence- unclear- frontal eye
fields and occipital regions produces convergence.
∀ Middle temporal region and parietal cortex discharge in
response to retinal disparity and objects moving in depth
∀ Neurons near oculomotor nucleus act as immediate pre-
motor neurons for Vergence
Gauri S. Shrestha, M.optom
51. Vergence
The supraoculomotor
nucleus contains burst
and tonic cells as well
as phasic-tonic cells
that are characteristic
of the saccadic
pathways.
Gauri S. Shrestha, M.optom
52. Vergence
It is thought that velocity signals related to disparity
stimlui innervate the bursters and that velocity information
is integrated to form the position signal that is processed
by the tonic cells.
Accommodative-vergence is already represented by these
cells so that the wiring for cross-coupling between
accommodation and convergence must occur more
centrally in the pathways.
Gauri S. Shrestha, M.optom
53. Supranuclear disorders
∀ Gaze palsies – disorders of saccade amplitudes
and appropriateness
∀ Saccadic dysmetria
∀ Vertical gaze palsy
∀ Internuclear ophthalmoplegia
Gauri S. Shrestha, M.optom