SlideShare a Scribd company logo
 Measurement of the convergence induced by
accommodation, per diopter of
accommodation.
 To determine the change in accommodative
convergence that occurs when the patient
accommodates or relaxes accommodates a
given amount.
 Unit = ∆∕D
 Normal range = ( 4 – 6) ∆/D
 Abnormalities of the AC/A ratio are very
important causes of strabismus.
 A high AC/A ratio may cause excessive
convergence & produce a convergent
squint during accommodation on a near
object.
 A low AC/A ratio may cause a divergent
squint when the patient looks at a near
object.
1. Stimulus AC/A Ratio
Ratio of accommodative convergence
to stimulus to accommodation.
2. Response AC/A Ratio
Ratio of accommodative convergence
to response to accommodation.
 Usually stimulus AC/A > Response AC/A
 Heterophoria method
 Gradient method
 Fixation disparity method
 Graphical method
 Simple method, consists of comparing the
measurement of the latent deviation of eyes
 Using prisms & alternate cover test at a point of
distance fixation ( 6m ) with refractive
correction.
 At a point of near fixation ( 33cm ) with
refractive correction.
 IPD should be measured.
 +ve sign for esodeviation, -ve sign for
exodeviation.
 AC/A ratio is calculated from this following
formula:-
AC/A = IPD + (∆n - ∆d/D)
 The change in the stimulus to
accommodation is produced by means of
ophthalmic lenses not by a change in
viewing distance.
 Concave lenses placed before the eyes
increase the requirement for accommodation
& convex lenses relax accommodation.
 -1D lenses produce an equivalent of 1D of
accommodation, where as +1D lenses relax
accommodation by 1D.
 Original deviation is found at near while the
patient wears optical correction & then with
additional lens.
 Ac/A ratio is calculated from this following
formula:-
AC/A = ∆L - ∆O/D
 Used by Ogle & co-workers.
 Indirect method, more reliable due to test
under binocular condition.
 Consists of 2 sets of data
 First changes in fixation disparity induced by force
convergence using prism
 Second change in fixation disparity induced by altering
the accommodative stimulus with lens
 From these 2 sets of data they determined
stimuli for convergence & accommodation
that gave same fixation disparity.
 Because of its complexity, this test is not
performed in routine clinical practice.
 Convergence (in prism diopter) is plotted
along the x- axis.
 Stimulus to accommodation is indicated
along the y-axis.
 Slope of graph represents AC/A ratio.
 Diagnosis of convergence excess type of
esodeviation.
 Divergence excess exodeviation
 Divergence insufficiency
 Convergence insufficiency
 Apply in those patient who have chance of
obtaining some fusion when eyes are straight
or within 10PD in distance with optical
correction.
 Try to keep eyes straight for distance upto
age of 8 years.
 If eso deviation is less then 10PD in distance-
has chance of developing fusion with full
optical correction.
 If eso deviation is greater than 10PD in
distance has no chance of developing fusion
unless the deviation is reduced to under
10PD.
 Prescribing Prism
 Prescribing Visual Training
 Alteration of Sph. Portion of Correction
 if AC/A sufficiently large additional plus for
convergence excess
 CONVERGENCE EXCESS:
 n>d
 high AC/A ratio
 Treatment
 Near add (overcorrection of plus power
or under correction of minus power
most effective) e.g.
 Base-out prism (alternative method)
 Base-in training(not so effective)
 CONVERGENCE INSUFFICIENCY
 n> d
 Low AC/A ratio
 Treatment
 Base-out training (most effective)
 “Pencil push-up” training
 DIVERGENCE EXCESS
 n< d
 high AC/A ratio
 Treatment
overcorrection of minus power or
undercorrection of plus power
in mild case base-in prism for full time
wear
 DIVERGENCE INSUFFICIENCY
 n>d
 low AC/a ratio
 Treatment
 Base-out prism
THANK YOU…….

More Related Content

What's hot

Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
Bikash Sapkota
 
Acaratio
AcaratioAcaratio
Acaratio
Hossein Mirzaie
 
Pattern Strabismus | A.V Pattern
Pattern Strabismus | A.V Pattern Pattern Strabismus | A.V Pattern
Pattern Strabismus | A.V Pattern
DrAzmat Ali
 
Synaptophore
SynaptophoreSynaptophore
Synaptophore
Manjusha Lakshmi
 
Binocular vision and vision perception
Binocular vision and vision perceptionBinocular vision and vision perception
Binocular vision and vision perception
Tukezban Huseynova, MD
 
Rgp lens
Rgp lensRgp lens
Optics of contact lens
Optics of contact lensOptics of contact lens
Optics of contact lens
Aayush Chandan
 
Contrast sensitivity
Contrast sensitivityContrast sensitivity
Contrast sensitivity
Laxmi Eye Institute
 
Fusion
FusionFusion
Fusion
Anand shah
 
Pediatric refraction
Pediatric       refractionPediatric       refraction
Pediatric refraction
Yashaswee Bhattarai
 
Soft Contact Lens Fitting
Soft Contact Lens FittingSoft Contact Lens Fitting
Soft Contact Lens Fitting
Vishakh Nair
 
ARC: abnormal retinal correspondence, eccentric fixation
ARC: abnormal retinal correspondence, eccentric fixationARC: abnormal retinal correspondence, eccentric fixation
ARC: abnormal retinal correspondence, eccentric fixation
aditi Jain
 
Special purpose frames
Special purpose framesSpecial purpose frames
Special purpose frames
Eyenirvaan
 
Binocular refraction techniques, binocular balancing
Binocular refraction techniques, binocular balancing Binocular refraction techniques, binocular balancing
Binocular refraction techniques, binocular balancing
Mohammad Arman Bin Aziz
 
Maddox rod
Maddox rodMaddox rod
Active Vision Therapy in Management of Amblyopia (healthkura.com)
Active Vision Therapy in Management of Amblyopia (healthkura.com)Active Vision Therapy in Management of Amblyopia (healthkura.com)
Active Vision Therapy in Management of Amblyopia (healthkura.com)
Bikash Sapkota
 
Ac/a ratio
Ac/a ratio Ac/a ratio
Ac/a ratio
anupama manoharan
 
subjective refraction
  subjective refraction  subjective refraction
subjective refraction
Hossein Mirzaie
 
Pediatric contact lens
Pediatric contact lensPediatric contact lens
Pediatric contact lens
Noor Munirah Aab
 
Accommodation and convergence
Accommodation and convergenceAccommodation and convergence
Accommodation and convergence
SAMEEKSHA AGRAWAL
 

What's hot (20)

Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
Accommodation/ Accommodation of Eye, Measurement of Accommodation of Eye (hea...
 
Acaratio
AcaratioAcaratio
Acaratio
 
Pattern Strabismus | A.V Pattern
Pattern Strabismus | A.V Pattern Pattern Strabismus | A.V Pattern
Pattern Strabismus | A.V Pattern
 
Synaptophore
SynaptophoreSynaptophore
Synaptophore
 
Binocular vision and vision perception
Binocular vision and vision perceptionBinocular vision and vision perception
Binocular vision and vision perception
 
Rgp lens
Rgp lensRgp lens
Rgp lens
 
Optics of contact lens
Optics of contact lensOptics of contact lens
Optics of contact lens
 
Contrast sensitivity
Contrast sensitivityContrast sensitivity
Contrast sensitivity
 
Fusion
FusionFusion
Fusion
 
Pediatric refraction
Pediatric       refractionPediatric       refraction
Pediatric refraction
 
Soft Contact Lens Fitting
Soft Contact Lens FittingSoft Contact Lens Fitting
Soft Contact Lens Fitting
 
ARC: abnormal retinal correspondence, eccentric fixation
ARC: abnormal retinal correspondence, eccentric fixationARC: abnormal retinal correspondence, eccentric fixation
ARC: abnormal retinal correspondence, eccentric fixation
 
Special purpose frames
Special purpose framesSpecial purpose frames
Special purpose frames
 
Binocular refraction techniques, binocular balancing
Binocular refraction techniques, binocular balancing Binocular refraction techniques, binocular balancing
Binocular refraction techniques, binocular balancing
 
Maddox rod
Maddox rodMaddox rod
Maddox rod
 
Active Vision Therapy in Management of Amblyopia (healthkura.com)
Active Vision Therapy in Management of Amblyopia (healthkura.com)Active Vision Therapy in Management of Amblyopia (healthkura.com)
Active Vision Therapy in Management of Amblyopia (healthkura.com)
 
Ac/a ratio
Ac/a ratio Ac/a ratio
Ac/a ratio
 
subjective refraction
  subjective refraction  subjective refraction
subjective refraction
 
Pediatric contact lens
Pediatric contact lensPediatric contact lens
Pediatric contact lens
 
Accommodation and convergence
Accommodation and convergenceAccommodation and convergence
Accommodation and convergence
 

Similar to AC/A

accommodative-convergence by jubairiya firoz
accommodative-convergence by jubairiya firozaccommodative-convergence by jubairiya firoz
accommodative-convergence by jubairiya firoz
OPTOM FASLU MUHAMMED
 
AC/A ratio
AC/A ratio AC/A ratio
AC/A ratio
mahendra singh
 
Examination protocol for binocular vision
Examination protocol for binocular visionExamination protocol for binocular vision
Examination protocol for binocular vision
Puneet
 
Accommodation presentation by Tamalika
Accommodation presentation by TamalikaAccommodation presentation by Tamalika
Accommodation presentation by Tamalika
Tamalika Biswas
 
Refraction Method by Siddhartha Khandewal ( Click below for Online Lecture)
Refraction Method by Siddhartha Khandewal ( Click below for Online  Lecture)Refraction Method by Siddhartha Khandewal ( Click below for Online  Lecture)
Refraction Method by Siddhartha Khandewal ( Click below for Online Lecture)
Mero Eye
 
Refraction
RefractionRefraction
Refraction
Irina Kezik
 
PRESBYOPIA the presentation ophthalmology
PRESBYOPIA the presentation ophthalmologyPRESBYOPIA the presentation ophthalmology
PRESBYOPIA the presentation ophthalmology
kadayathsandeep
 
Synoptophore.pptx
Synoptophore.pptxSynoptophore.pptx
Synoptophore.pptx
Anisha Heka
 
Accomodative convergance and accommodation
Accomodative convergance and accommodationAccomodative convergance and accommodation
Accomodative convergance and accommodation
Paramedical college, U.P.University of Medical Sciences
 
Methods of subjective refraction
Methods of subjective refractionMethods of subjective refraction
Methods of subjective refraction
Maryam Fashola
 
Objective Refraction and Subjective Refraction
Objective Refraction and Subjective RefractionObjective Refraction and Subjective Refraction
Objective Refraction and Subjective Refraction
AnuMusyakhwo7
 
Visual function assessment in low vision
Visual function assessment in low visionVisual function assessment in low vision
Visual function assessment in low vision
Puneet
 
Accommodative convergence
Accommodative convergenceAccommodative convergence
Accommodative convergence
SHREYA TALDEOKAR
 
Accommodative convergence
Accommodative convergenceAccommodative convergence
Accommodative convergence
SHREYA TALDEOKAR
 
Subjective refraction
Subjective refractionSubjective refraction
Subjective refraction
sanju_95
 
Prism
PrismPrism
Prism
meenank
 
Refraction
RefractionRefraction
Refraction
Aivaras Daukontas
 
Hirschberg and krimsky test.pptx
Hirschberg and krimsky test.pptxHirschberg and krimsky test.pptx
Hirschberg and krimsky test.pptx
jyotishah48
 
Synoptophore Information Guide
Synoptophore Information GuideSynoptophore Information Guide
Synoptophore Information Guide
Haag-Streit UK (HS-UK)
 
AC/A
AC/AAC/A

Similar to AC/A (20)

accommodative-convergence by jubairiya firoz
accommodative-convergence by jubairiya firozaccommodative-convergence by jubairiya firoz
accommodative-convergence by jubairiya firoz
 
AC/A ratio
AC/A ratio AC/A ratio
AC/A ratio
 
Examination protocol for binocular vision
Examination protocol for binocular visionExamination protocol for binocular vision
Examination protocol for binocular vision
 
Accommodation presentation by Tamalika
Accommodation presentation by TamalikaAccommodation presentation by Tamalika
Accommodation presentation by Tamalika
 
Refraction Method by Siddhartha Khandewal ( Click below for Online Lecture)
Refraction Method by Siddhartha Khandewal ( Click below for Online  Lecture)Refraction Method by Siddhartha Khandewal ( Click below for Online  Lecture)
Refraction Method by Siddhartha Khandewal ( Click below for Online Lecture)
 
Refraction
RefractionRefraction
Refraction
 
PRESBYOPIA the presentation ophthalmology
PRESBYOPIA the presentation ophthalmologyPRESBYOPIA the presentation ophthalmology
PRESBYOPIA the presentation ophthalmology
 
Synoptophore.pptx
Synoptophore.pptxSynoptophore.pptx
Synoptophore.pptx
 
Accomodative convergance and accommodation
Accomodative convergance and accommodationAccomodative convergance and accommodation
Accomodative convergance and accommodation
 
Methods of subjective refraction
Methods of subjective refractionMethods of subjective refraction
Methods of subjective refraction
 
Objective Refraction and Subjective Refraction
Objective Refraction and Subjective RefractionObjective Refraction and Subjective Refraction
Objective Refraction and Subjective Refraction
 
Visual function assessment in low vision
Visual function assessment in low visionVisual function assessment in low vision
Visual function assessment in low vision
 
Accommodative convergence
Accommodative convergenceAccommodative convergence
Accommodative convergence
 
Accommodative convergence
Accommodative convergenceAccommodative convergence
Accommodative convergence
 
Subjective refraction
Subjective refractionSubjective refraction
Subjective refraction
 
Prism
PrismPrism
Prism
 
Refraction
RefractionRefraction
Refraction
 
Hirschberg and krimsky test.pptx
Hirschberg and krimsky test.pptxHirschberg and krimsky test.pptx
Hirschberg and krimsky test.pptx
 
Synoptophore Information Guide
Synoptophore Information GuideSynoptophore Information Guide
Synoptophore Information Guide
 
AC/A
AC/AAC/A
AC/A
 

Recently uploaded

The Ultimate Guide in Setting Up Market Research System in Health-Tech
The Ultimate Guide in Setting Up Market Research System in Health-TechThe Ultimate Guide in Setting Up Market Research System in Health-Tech
The Ultimate Guide in Setting Up Market Research System in Health-Tech
Gokul Rangarajan
 
nurs fpx 4050 assessment 4 final care coordination plan.pdf
nurs fpx 4050 assessment 4 final care coordination plan.pdfnurs fpx 4050 assessment 4 final care coordination plan.pdf
nurs fpx 4050 assessment 4 final care coordination plan.pdf
Carolyn Harker
 
CHAPTER 1 SEMESTER V COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
CHAPTER 1 SEMESTER V  COMMUNICATION TECHNIQUES FOR CHILDREN.pdfCHAPTER 1 SEMESTER V  COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
CHAPTER 1 SEMESTER V COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
Sachin Sharma
 
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
5sj7jxf7
 
3. User Guide Activity Budget Tracking App Steps to apply.pptx
3. User Guide Activity Budget Tracking App Steps to apply.pptx3. User Guide Activity Budget Tracking App Steps to apply.pptx
3. User Guide Activity Budget Tracking App Steps to apply.pptx
habtegirma
 
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdfnhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
Carolyn Harker
 
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
rightmanforbloodline
 
Solution manual for managerial accounting 18th edition by ray garrison eric n...
Solution manual for managerial accounting 18th edition by ray garrison eric n...Solution manual for managerial accounting 18th edition by ray garrison eric n...
Solution manual for managerial accounting 18th edition by ray garrison eric n...
rightmanforbloodline
 
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
The Lifesciences Magazine
 
DAHL APPROACH a novel technique to raise bite
DAHL APPROACH a novel technique to raise biteDAHL APPROACH a novel technique to raise bite
DAHL APPROACH a novel technique to raise bite
SuraiyaTaranum
 
Columbia毕业证书退学办理
Columbia毕业证书退学办理Columbia毕业证书退学办理
Columbia毕业证书退学办理
ozcot
 
Mental Health and Physical Wellbeing.pdf
Mental Health and Physical Wellbeing.pdfMental Health and Physical Wellbeing.pdf
Mental Health and Physical Wellbeing.pdf
shindesupriya013
 
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
xkute
 
Friendly Massage in Ajman - Malayali Kerala Spa Ajman
Friendly Massage in Ajman - Malayali Kerala Spa AjmanFriendly Massage in Ajman - Malayali Kerala Spa Ajman
Friendly Massage in Ajman - Malayali Kerala Spa Ajman
Malayali Kerala Spa Ajman
 
Pneumothorax and role of Physiotherapy in it.
Pneumothorax and role of Physiotherapy in it.Pneumothorax and role of Physiotherapy in it.
Pneumothorax and role of Physiotherapy in it.
Vishal kr Thakur
 
Test bank clinical nursing skills a concept based approach 4e pearson educati...
Test bank clinical nursing skills a concept based approach 4e pearson educati...Test bank clinical nursing skills a concept based approach 4e pearson educati...
Test bank clinical nursing skills a concept based approach 4e pearson educati...
rightmanforbloodline
 
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
Pristyn Care Reviews
 
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
Media Logic
 
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 BathindaBathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
varun0kumar00
 
Emotional and Behavioural Problems in Children - Counselling and Family Thera...
Emotional and Behavioural Problems in Children - Counselling and Family Thera...Emotional and Behavioural Problems in Children - Counselling and Family Thera...
Emotional and Behavioural Problems in Children - Counselling and Family Thera...
PsychoTech Services
 

Recently uploaded (20)

The Ultimate Guide in Setting Up Market Research System in Health-Tech
The Ultimate Guide in Setting Up Market Research System in Health-TechThe Ultimate Guide in Setting Up Market Research System in Health-Tech
The Ultimate Guide in Setting Up Market Research System in Health-Tech
 
nurs fpx 4050 assessment 4 final care coordination plan.pdf
nurs fpx 4050 assessment 4 final care coordination plan.pdfnurs fpx 4050 assessment 4 final care coordination plan.pdf
nurs fpx 4050 assessment 4 final care coordination plan.pdf
 
CHAPTER 1 SEMESTER V COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
CHAPTER 1 SEMESTER V  COMMUNICATION TECHNIQUES FOR CHILDREN.pdfCHAPTER 1 SEMESTER V  COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
CHAPTER 1 SEMESTER V COMMUNICATION TECHNIQUES FOR CHILDREN.pdf
 
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
1比1制作(uofm毕业证书)美国密歇根大学毕业证学位证书原版一模一样
 
3. User Guide Activity Budget Tracking App Steps to apply.pptx
3. User Guide Activity Budget Tracking App Steps to apply.pptx3. User Guide Activity Budget Tracking App Steps to apply.pptx
3. User Guide Activity Budget Tracking App Steps to apply.pptx
 
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdfnhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
nhs fpx 4000 assessment 4 analyzing a current health care problem or issue.pdf
 
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
TEST BANK FOR Health Assessment in Nursing 7th Edition by Weber Chapters 1 - ...
 
Solution manual for managerial accounting 18th edition by ray garrison eric n...
Solution manual for managerial accounting 18th edition by ray garrison eric n...Solution manual for managerial accounting 18th edition by ray garrison eric n...
Solution manual for managerial accounting 18th edition by ray garrison eric n...
 
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
Cyclothymia Test: Diagnosing, Symptoms, Treatment, and Impact | The Lifescien...
 
DAHL APPROACH a novel technique to raise bite
DAHL APPROACH a novel technique to raise biteDAHL APPROACH a novel technique to raise bite
DAHL APPROACH a novel technique to raise bite
 
Columbia毕业证书退学办理
Columbia毕业证书退学办理Columbia毕业证书退学办理
Columbia毕业证书退学办理
 
Mental Health and Physical Wellbeing.pdf
Mental Health and Physical Wellbeing.pdfMental Health and Physical Wellbeing.pdf
Mental Health and Physical Wellbeing.pdf
 
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
一比一原版(UoA毕业证)昆士兰科技大学毕业证如何办理
 
Friendly Massage in Ajman - Malayali Kerala Spa Ajman
Friendly Massage in Ajman - Malayali Kerala Spa AjmanFriendly Massage in Ajman - Malayali Kerala Spa Ajman
Friendly Massage in Ajman - Malayali Kerala Spa Ajman
 
Pneumothorax and role of Physiotherapy in it.
Pneumothorax and role of Physiotherapy in it.Pneumothorax and role of Physiotherapy in it.
Pneumothorax and role of Physiotherapy in it.
 
Test bank clinical nursing skills a concept based approach 4e pearson educati...
Test bank clinical nursing skills a concept based approach 4e pearson educati...Test bank clinical nursing skills a concept based approach 4e pearson educati...
Test bank clinical nursing skills a concept based approach 4e pearson educati...
 
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
Enhancing Hip and Knee Arthroplasty Precision with Preoperative CT and MRI Im...
 
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
2024 Media Preferences of Older Adults: Consumer Survey and Marketing Implica...
 
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 BathindaBathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
Bathinda ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 7742996321 ℂ𝕒𝕝𝕝 𝔾𝕚𝕣𝕝𝕤 Bathinda
 
Emotional and Behavioural Problems in Children - Counselling and Family Thera...
Emotional and Behavioural Problems in Children - Counselling and Family Thera...Emotional and Behavioural Problems in Children - Counselling and Family Thera...
Emotional and Behavioural Problems in Children - Counselling and Family Thera...
 

AC/A

  • 1.
  • 2.  Measurement of the convergence induced by accommodation, per diopter of accommodation.  To determine the change in accommodative convergence that occurs when the patient accommodates or relaxes accommodates a given amount.  Unit = ∆∕D  Normal range = ( 4 – 6) ∆/D
  • 3.  Abnormalities of the AC/A ratio are very important causes of strabismus.  A high AC/A ratio may cause excessive convergence & produce a convergent squint during accommodation on a near object.  A low AC/A ratio may cause a divergent squint when the patient looks at a near object.
  • 4. 1. Stimulus AC/A Ratio Ratio of accommodative convergence to stimulus to accommodation. 2. Response AC/A Ratio Ratio of accommodative convergence to response to accommodation.  Usually stimulus AC/A > Response AC/A
  • 5.  Heterophoria method  Gradient method  Fixation disparity method  Graphical method
  • 6.  Simple method, consists of comparing the measurement of the latent deviation of eyes  Using prisms & alternate cover test at a point of distance fixation ( 6m ) with refractive correction.  At a point of near fixation ( 33cm ) with refractive correction.  IPD should be measured.  +ve sign for esodeviation, -ve sign for exodeviation.
  • 7.  AC/A ratio is calculated from this following formula:- AC/A = IPD + (∆n - ∆d/D)
  • 8.  The change in the stimulus to accommodation is produced by means of ophthalmic lenses not by a change in viewing distance.  Concave lenses placed before the eyes increase the requirement for accommodation & convex lenses relax accommodation.  -1D lenses produce an equivalent of 1D of accommodation, where as +1D lenses relax accommodation by 1D.
  • 9.  Original deviation is found at near while the patient wears optical correction & then with additional lens.  Ac/A ratio is calculated from this following formula:- AC/A = ∆L - ∆O/D
  • 10.  Used by Ogle & co-workers.  Indirect method, more reliable due to test under binocular condition.  Consists of 2 sets of data  First changes in fixation disparity induced by force convergence using prism  Second change in fixation disparity induced by altering the accommodative stimulus with lens
  • 11.  From these 2 sets of data they determined stimuli for convergence & accommodation that gave same fixation disparity.  Because of its complexity, this test is not performed in routine clinical practice.
  • 12.  Convergence (in prism diopter) is plotted along the x- axis.  Stimulus to accommodation is indicated along the y-axis.  Slope of graph represents AC/A ratio.
  • 13.
  • 14.  Diagnosis of convergence excess type of esodeviation.  Divergence excess exodeviation  Divergence insufficiency  Convergence insufficiency
  • 15.  Apply in those patient who have chance of obtaining some fusion when eyes are straight or within 10PD in distance with optical correction.  Try to keep eyes straight for distance upto age of 8 years.
  • 16.  If eso deviation is less then 10PD in distance- has chance of developing fusion with full optical correction.  If eso deviation is greater than 10PD in distance has no chance of developing fusion unless the deviation is reduced to under 10PD.
  • 17.  Prescribing Prism  Prescribing Visual Training  Alteration of Sph. Portion of Correction  if AC/A sufficiently large additional plus for convergence excess
  • 18.  CONVERGENCE EXCESS:  n>d  high AC/A ratio  Treatment  Near add (overcorrection of plus power or under correction of minus power most effective) e.g.  Base-out prism (alternative method)  Base-in training(not so effective)
  • 19.  CONVERGENCE INSUFFICIENCY  n> d  Low AC/A ratio  Treatment  Base-out training (most effective)  “Pencil push-up” training
  • 20.  DIVERGENCE EXCESS  n< d  high AC/A ratio  Treatment overcorrection of minus power or undercorrection of plus power in mild case base-in prism for full time wear
  • 21.  DIVERGENCE INSUFFICIENCY  n>d  low AC/a ratio  Treatment  Base-out prism