This document summarizes accommodation and its anomalies. Accommodation allows the eye to focus on near objects by changing the lens shape. With age, the lens loses elasticity causing presbyopia. Anomalies include decreased accommodation like insufficiency and inertia, as well as increased accommodation like spasm. Accommodation insufficiency results in blurred near vision. Treatments include lenses, vision therapy, and ciliary muscle relaxation for spasm.

1. ACCOMMODATION
AND ITSANOMALIES
Sahibzada Hakim Anjum Nadeem
Co-Incharge OTTC, Optician, Refractionist, COAVS
CEO Anjum Eye Care & Optical Company
Optometrist, Al-Khair Eye Hospital Lahore
Email: shanjum92@gmail.com

2. • Dioptric adjustment of the crystalline lens of the eye
- to obtain clear vision for a given target of regard
• Process by which the refractive power of eye is altered
- to ensure a clear retinal image
Accommodation

3. • In an emmetropic eye
- parallel rays of light coming from infinity are brought to
focus on retina being accommodation at rest
- eyes can also focus diverging rays coming from near
object on retina to see clearly due to ACCOMMODATION

5. Mechanism of Accommodation
As a result
Allowing near object to be
focused clearly on retina
Ciliary muscle contracts Ciliary ring shortens
Increase in
dioptric power
Lens becomes spherical i.e.
convexity increases
Tension in capsule is relievedZonules are relaxed
Equator of lens move forward

7. With Age
lens fibers & lens
capsule lose elasticity
the size & shape of
the lens increase
reduction of
accommodative amplitude
onset of presbyopia

8. Ocular changes during Accommodation
Anterior r =11 mm
Posterior r = 6 mm
T = 4 mm

9. Ocular changes in Accommodation
• Slackening of zonules – due to contraction of
ciliary muscles
• Change in curvature of lens
- almost no change in posterior surface (6 mm)
- anterior surface radius of curvature
(from 11 mm to 6 mm)

10. • Anterior pole along with iris moves forward
- shallowing of anterior chamber in centre
• Pupillary constriction and convergence of eyes
- near triad
• Choroid moves forward
• Ora serrata moves by 0.05mm forward with each
diopter of accommodation

11. Lens shape change with Accommodation
Anterior r =6 mm

12. What triggers Accommodation ??
• Image blur
• Apparent size and
distance of object
• Disparate retinal images
• Contrast
• Luminance
• Chromatic aberration

13. Components of Accommodation
Components
Tonic
Proximal
Vergence
Reflex

14. Reflex Accommodation
• The normal involuntary response to blur which
maintains a clear image
• Largest and most important component
• Automatic adjustment of refractive state to obtain
clear retinal image
• Occurs for small amount of blur, upto 2.00 D, beyond
which voluntary effort is required
Voluntary Accommodation

15. Vergence Accommodation
• Induced due to action of disparity (fusional) Vergence.
• Second major component of accommodation

16. Proximal Accommodation
• Due to influence or knowledge of apparent nearness
of object
• Stimulated by targets located within 3m of the
individual
• Tertiary component of accommodation

17. Tonic Accommodation
• Revealed in absence of blur, disparity, and proximal
inputs as well as any voluntary or learned unusual
aspects.
• Reflects baseline neural innervation from the midbrain.
• In young adults, ranges from 0 to 2 D

18. Measurement of Accommodation
A full clinical examination includes assessment of
accommodative function in five parameters
o Amplitude of accommodation
o Lag of accommodation
o Accommodative facility
o Relative accommodation
o Accommodation fatigue

19. Amplitude of Accommodation
• Punctum Remotum
- The farthest point at which the objects can be seen
clearly
- Infinity for emmetropic eyes
• Punctum Proximum
- The nearest point at which objects can be seen clearly

21. • Range of accommodation
- Distance between near point and far point
• Amplitude of accommodation
- The dioptric difference between near point
and far point
(A= P-R)
Amplitude of Accommodation

22. Measurement of Amplitude of Accommodation
• Push up method
• Minus lens method

23. Push Up Method
- To determine maximum amount of accommodation that
eyes are capable of producing individually or together
- Done by RAF Rule, Livingstone Binocular Gauge,Prince Rule
Measurement of Amplitude of Accommodation

24. Royal Air Force Rule
Wing like support that fits over
nose and rests against lower orbital
margins
Test chart
Metal rod
1st side : divided into cm for NPA
2nd side : divided into diopter(NPA in D)
3rd side : age
Prince Rule

25. Procedure:
• Near visual acuity chart placed on near
point rod
• Direct patient’s attention to 20/20 line of
letters on near point card
• Patient left eye occluded

26. • Near point card brought closer to
patient (2-3 inches per second)
• Patient instructed to keep the letters as
clear as possible and report when it
blurs
• Prompt the patient to clear the target

27. • Stop when patient can no longer clear the
print within 2 to 3 seconds of viewing
• Record the dioptric points on the near point
rod that corresponds with the blur
• Procedure repeated for left eye

28.  Hofstetter formulae for expected
amplitude as a function of age (using
the data of Donders, Duane and
Kaufman)
• Maximum amplitude = 25 - 0.4(age)
• Probable amplitude = 18.5 - 0.3(age)
• Minimum amplitude = 15 - 0.25(age)
Formula to determine Amplitude of Accommodation

29. Example :
• For 20 years old patient
Minimum AA is given by :
15 – 0.25 x age= 15 – 0.25 x 20
= 10 DS
NPA = 1 /10
= 0.1m
= 0.1 x 100 cm
= 10 cm

30. Accommodation Insufficiency & presbyopia
AI PRESBYOPIA
Accommodative power is
significantly less than the
normal physiological limit
for the patient’s age
Physiological insufficiency
of accommodation is
normal for age
Asthenopic symptoms are
more prominent
Symptoms of decreased
near VA is more
prominent

31. Amplitude of accommodation and age
The amplitude of accommodation declines throughout life
until at about 50 or 60 years of age when it becomes zero

32. • Rule of 4’s
Amplitude= 4x4-(Age/4)
Example:
Age of 20,
Amplitude = 16-20/4
= 11 diopters
Amplitude of accommodation and age

33. ANOMALIES OF ACCOMMODATION
Classification
Decreased
Accommodation
Insufficiency
Ill-Sustained
Accommodation
Inertia Paralysis
Increased
Accommodation
Excess Spasm

34. • General symptoms:
• Intermittently blurred vision
• Eyestrain and/or headache with visual tasks
• Fatigue/sleepiness with visual tasks
• Inattentiveness over time

35. ACCOMMODATION INSUFFICIENCY
• The accommodative amplitude is distinctly below the
lower limit of the expected amplitude in relation to
the age of the individual
• Similar to presbyopia
• Can result from systemic conditions such as diabetes
mellitus, multiple sclerosis, anemia, general physical
fatigue, myasthenia gravis, trauma, malnutrition,
convalescence from debilitating illnesses and chronic
alcoholism

36. • Specific symptoms:
• Blurred vision/eyestrain with NEAR visual tasks
• Intermittent diplopia due to associated disturbances of
convergence

37. RULE OUT…
Causes of Unilateral Accommodation Failure:
• Congenital unilateral third nerve palsy
• Transient, post traumatic, accommodation failure associated with traumatic
mydriasis
Causes of Bilateral Accommodation Failure:
• Cortical vision impairment
• Foveal hypoplasia (albinism, aniridia)
• Down syndrome
• Iso-ametropic amblyopia
• Ectopia lentis
• Macular degeneration
• Nanophthalmos
• Near vision palsy

38. TREATMENT:
• Spectacle correction
• For near- weakest convex lenses should be
prescribed
• If there is associated convergence insufficiency
base out prism may be added to patient
comfort
• In cases with convergence excess full spherical
correction should be prescribed

39. • Vision Therapy: To stimulate accommodation mono-
ocularly
• Small print targets that are slowly moved CLOSER to the eye
• Reading print through MINUS lenses (gradually increasing the
power) using “Monocular minus lens rock”
• Monocular lens flippers
• Monocular minus lens clear/blur/clear (for fine voluntary
control)
• Binocular lens flippers

40. ILL-SUSTAINED ACCOMMODATION
• Initial stage of true insufficiency
• Range is normal
• During prolonged near work, accommodative
power weakens, the near point gradually
recedes and vision becomes blurred

41. INERTIA OF ACCOMMODATION
• Rare condition
• Difficulty in altering the range of accommodation
• Requires time and effort to focus a near object after
looking into distance
• Treatment:
• Correction of refractive error
• Accommodative Exercises

42. PARALYSIS OF ACCOMMODATION
• Causes:
• Drug induced cycloplegia –atropine ,homatropine
• Internal opthalmoplegia [paralysis of cilliary muscle & sphincter pupillae]
• Neuritis associated with chronic alcoholism, diabetes
• CNS infections
• Head Injury
• Specific Symptoms:
• Blurring of near vision
• Photophobia [glare]

43. TREATMENT:
• Self recovery occurs in drug induced paralysis
• Dark glasses are effective in reducing the glare
• Convex lenses for near vision may be
prescribed

44. TREATMENT: ACCOMMODATION EXCESS
• Prescribing lenses
• Distance lens prescription
• Added plus lenses are not usually accepted for near work
• Vision Therapy: To relax accommodation monocularly
• Small print targets slowly moved AWAY from the eye
• Reading print through PLUS lenses (gradually increasing the
power)

45. SPASM OF ACCOMMODATION
• Abnormally excessive accommodation which is
out of voluntary control of the individual
• Causes:
• Drug induced spasm after use of strong miotics
• Spasm of near reflex

46. • Specific symptoms:
Blurred vision at DISTANCE after performing near
visual tasks
• Treatment:
Relaxation of ciliary muscle: the most effective
method of treatment is complete ciliary paralysis with
atropine