Definition Of The Accommodation Mechanism Of Accommodation Triggers Accommodation Terms Of Accommodation Accommodative Dysfunction Spasm Of Accommodation Accommodative Esotropia Controlling Accommodation In Vision Test Tips To Control Accommodation In Lifestyle References Clinical Procedures In Optometry By J.D. Bartlett, J.B. Eskridge, J.F. Amos Theory And Practice Of Squint And Orthoptics By A.K.Khurana Adler’s Physiology Of The Eye By L.A. Levin, S.F. Nilsson Borish’s Clinical Refraction By W.J. Benjamin Duke-elder’s Practice Of Refraction By David Abrams Optics & Refraction By A.K.Khurana Textbook Of Ophthalmology By E Ahmed Clinical Optics By A R. Elkington, Werner L, Trindade F, Pereira F, Werner L Physiology Of Accommodation And Presbyopia, ARQ. Bras. OFTALMOL, December 2000. Optometry And Ophthalmology Websites

2. Presenter
Mohamed said Ibrahim
Careers:
• Key Account sales Manger, Nikon Lenswear
• Sr.Optometrist, Hadi Hospital
• International Member of the American Optometric Association
• Certified International Professional Trainer (CIPT)
• Ambassador of the Arab British Academy for Higher Education
• Advanced Member of the UK Professional Board
• Trainer of BARAKA AND C&CO. Optics (earlier)
• Demonstrated and lecturer of the High optics technology institute (earlier)
Educational:
 PhD researcher in visual behavioural rehabilitation for vision defects
 Master Degree of projects management in optics and vision sciences by the
faculty of projects management at Maryland University, USA
 BS.C in optics technology and vision science
 achieved degree of many short diplomas in health, patient care, customer
service, business administration.
Experience:
 More than 15 years of experience for optical shops, optical products, and
optometry clinic

3. » Definition Of The Accommodation
» Mechanism Of Accommodation
» Triggers Accommodation
» Terms Of Accommodation
» Accommodative Dysfunction
» Spasm Of Accommodation
» Accommodative Esotropia
» Controlling Accommodation In Vision Test
» Tips To Control Accommodation In Lifestyle
Topics

4. » Accommodation Is The Mechanism By Which The Eye Changes Refractive Power By Altering
The Shape Of crystalline Lens In Order To Focus Objects At Variable Distances
60 D
70 D

5. » Mechanism of Accommodation

6. » Triggers Accommodation
Chromatic aberration
Image Blur
Apparent size and
distance of object
Disparate retinal images
ContrastLuminance

7. » Terms of Accommodation
Amplitude Of Accommodation (AA) :
Dioptric Power Difference Between Rest And Fully Accommodated Eye. A=p-r
A: Amplitude Of Accommodation, P: Dioptric Value Of Near Point, And R: Dioptric Value Of Far Point.
Accommodative Convergence /Accommodation (AC/A) Ratio :
The Number Of Prism Dioptres Of Convergence Which Accompanies Each Dioptre Of Accommodation.
The Normal Range For The AC/A Ratio Is 3:1 To 5:1

8. » Terms of Accommodation
Lag of Accommodation :
Time lapse between the presentation of an accommodative stimulus and occurrence of the accommodative
response = Accommodative stimulus – Accommodative response
Average time : - Far to near accommodation is 0.64 seconds
- Near to far accommodation is 0.56 seconds
Accommodative Facility :
The Ease of Accommodative Response To The Change In Stimulus, Provides An Index of How Quickly
Accommodation Can Change.
Accommodative Infacility = Decreased Accommodative Facility.

9. » Terms of Accommodation
Accommodation Fatigue :
decrease of Amplitude of Accommodation
Relative Accommodation :
The Amount Of Accommodation To Be Exerted Under Fixed Convergence.
- Negative Relative Accommodation : Decrease Accommodation While Maintaining Convergence At 40 Cm
- Positive Relative Accommodation : Increase Accommodation While Maintaining Convergence At 40 Cm

10. » Accommodative Dysfunction

11. » Spasm of Accommodation
Definition : Refers to Exertion of Abnormally Excessive Accommodation.
Causes :
- Excessive Near Work with Bad Illumination, Bad Reading Position, State of Neurosis, Stress or Anxiety.
- Compensate for a refractive error.
- Use of strong miotics.
Symptoms :
- blurred Far vision due to induced myopia (Pseudo Myopia), or latent hyperopia.
- Asthenopic (pain around the eyes, headache, dry or watery eyes, burning, sore, or tired eyes.
Treatment :
- Relaxation of ciliary muscle by cycloplegia eye drops and plus lens for near work.
- Elimination of the associated causative factors to prevent the recurrence

12. » Accommodative Esotropia
Definition : a condition (strabismus) the appearance of one eye "turning" inwards in relation to the other.
This eye turning may be constant, in which an eye turns all the time, or it may be intermittent. It may also
alternate so that either eye turns at any given time
Causes :
1) Uncorrected Farsightedness (hyperopia)
2) Over-reaction of the focusing system with small amounts of refractive error. (High ratio AC/A)

13. » Accommodative Esotropia
Symptoms :
- Double Vision (diplopia), difficulty judging distances, eyestrain, blurred vision, sleepiness.
- Asthenopic (pain around the eyes, headache, dry or watery eyes, burning, sore, or tired eyes.
- Difficulty concentrating, movement of print while reading, and loss of comprehension after short periods
of reading or performing close activities.
- A person with a constant eye turn may only notice a few of these symptoms or none at all
Treatment :
- The best prescription glasses possible. These glasses may include bifocals and prism.
- Vision therapy can include the use of lenses, prisms, filters, computerized procedures and/or Manual.
- Surgery the last treatment option considered and then post-op vision therapy.

14. » Controlling Accommodation In Vision Test
INTRODUCTION :
- Complicated part of vision is accommodation.
- Accommodation must be controlled by the examiner as most patients do not even realise accommodating
- Very active accommodation (Such as Kids) difficulty controlling it.
- A patient who has poorly controlled accommodation will give you unexpected refraction results.
- uncontrolled accommodation can cause errors in refraction
- The patient will need to over accommodate to see clearly when spectacles with too much minus (or not
enough plus), This can cause asthenopia (eye strain and headaches).

15. » Controlling Accommodation In Vision Test
In Eye Test Room :
- Prepare the suitable room light and distance to stop stimulus triggers for accommodation.
- Recognise the signs that indicate that a patient’s accommodation is uncontrolled
- Avoid over-minus (or under-plus) during a refraction ( Using +1.00 blur TEST ).
- Measure the unaided VA can estimate the amount of refractive error that each 0.25 D refractive error
= approximately one line of VA:

16. » Controlling Accommodation In Vision Test
How To Control Accommodation :
1) Stop the eye accommodating from the beginning.
2) Always show plus lenses before minus lenses (minus lens for eye does not need it will accommodate).
3) Check to see that the person is really seeing better or just make it look smaller and blacker, “smaller
and blacker” means that the person is probably accommodating and you are adding too much minus.
4) When refracting hyperopic eyes : put the higher plus trial lens first.
5) When refracting myopic eyes : put the lower minus trial lens first.
6) Check the VA before adding minus lenses (or removing plus lenses), VA does not improve, do not add
the minus lens (or remove the plus lens).
7) If you think the patient is accommodating, add more plus and decrease the plus power slowly and
encourage the person to try hard or “guess” the next VA line even if they are not sure
8) Cycloplegic eye drops are used to temporarily that the eye cannot accommodate.

17. » Controlling Accommodation In Vision Test
+1.00 Blur TEST (Humphriss's Fogging Method) :
1) Fog the left eye with +0.75 or +1.00DS until the VA has been
reduced to 2 or 3 lines less than the BCVA.
2) Repeat the best vision sphere assessment for the right eye.
3) If significant positive power needs to be added (e.g. latent
hyperopia) this should relax accommodation in both eyes.
4) To ensure the amount of fogging is still effective, place additional
plus power over the left eye.
5) Remove the fog from the left eye and fog the right eye, repeat BSV
technique for the left eye.

18. » Patient’s tips to Control Accommodation In Lifestyle
Adjust The Lighting
Reduce Glare And Balance Light Between The Room And The Screen
Take Breaks
Take Occasional Breaks And Rest Your Eyes By Looking Away From The
Digital Screen.

19. » Patient’s tips to Control Accommodation In Lifestyle
The Right Eyewear
If You Need Glasses Or Contacts For Near Work Consider It, Designed
Specifically For Computer Work ( Lens Coatings And Tints) That Might
Help Too.
Adjust Your Position At Near Work :
Sitting About 68cm (Right About At Arm's Length) From The Target.
Also, Position The Target So Your Eye Gazes Slightly Downward, Not
Straight Ahead Or Up.

20. » Patient’s tips to Control Accommodation In Lifestyle
Follow The “20-20-20” Rule :
Every 20 Minutes, Shift Your Eyes To Look
At An Object At Least 20 Feet Away, For At
Least 20 Seconds.

21. » References
I. Clinical Procedures In Optometry By J.D. Bartlett, J.B. Eskridge, J.F. Amos
II. Theory And Practice Of Squint And Orthoptics By A.K.Khurana
III. Adler’s Physiology Of The Eye By L.A. Levin, S.F. Nilsson
IV. Borish’s Clinical Refraction By W.J. Benjamin
V. Duke-elder’s Practice Of Refraction By David Abrams
VI. Optics & Refraction By A.K.Khurana
VII. Textbook Of Ophthalmology By E Ahmed
VIII.Clinical Optics By A R. Elkington, Werner L, Trindade F, Pereira F, Werner L
IX. Physiology Of Accommodation And Presbyopia, ARQ. Bras. OFTALMOL, December
2000.
X. Optometry And Ophthalmology Websites