given all information about accommodation in eye....

1. ACCOMMODA
TION
PRESENTED BY : SWATI PANARA
FROM : BHARTIMAIYA COLLEGE OF
OPTOMETRY
3rd YEAR 5th SEMESTER

2. ACCOMMODATION
 An emmetropic eye , parallel rays of light coming from
infinity are brought to focus on the retina , with
accommodation at rest.
 Our eyes have been provided with a unique mechanism by
which we can even focus the diverging rays coming from a
near object on the retina in a bid to see clearly.
 This mechanism is called accommodation.

4. STIMULUS FOR ACCOMMODATION
• Apparent size for distance of object
• Chromatic aberration
• Blurred retinal image
• oscillation of accommodation
• Scanning movement of the eye.

5. TERMS
 Far point of accommodation
 It is the farthest point at which object can be
seen clearly with minimum accommodation
 It is also called punctum remotum
 Near point of accommodation
 It is the nearest point at which object can be
seen clearly with maximum accommodation
It is also called punctum remotum

7.  Range of accommodation
 It is the distance between far point and near
point of accommodation
 a = r- P
 Amplitude of accommodation
 The difference between dioptric power
needed to focus near and to focus far object
 A= P-R

8. • In a emmetropic eye , far point is at infinity.

9. • In a hypermetropic eye far point is virtual and
lies behind the eye.

10. • In a myopic eye , far point is real and lies in
front of the eye.

11. DEPTH OF FIELD
• The range of distance from the eye in which an
object appears clear without change of
accommodation is termed as depth of field

13. DEPTH OF FOCUS
• THE RANGE AT THE RETINA ON WHICH
AN OPTICAL IMAGE MAY MOVE
WITHOUT IMPAIRED OF Clarity IS
TERMED AS DEPTH OF FOCUS.

16. PATHWAY OF ACCOMMODATION

18. MECHANISM OF ACCOMMODATION
• Some fish retract their lenses to focus on
distant object.
• Snakes and frogs have mechanism to move
the lens forward for near vision.
• In man the process of accommodation is
achieved by a change in the shape of the lens.

19. MECHANISM
Changes during accommodation:
(A), contraction of ciliary
muscles; (B), approximation of
ciliary muscles to lens; (C),
relaxation of suspensory
ligament; (D), increased
curvature of anterior surface of
lens.

20. REACTION TIME
“ far-to-near” accommodation - 0.64 sec
 “near-to-far” accommodation - 0.56 sec
Contraction of the pupil - 0.26 to 0.30 sec
Convergence response - 0.20 sec

21. ANOMALIES OF ACCOMMODATION
DIMINISHED
ACCOMMODATION INCREASED
ACCOMMODATION

22. DIMINISHED ACCOMMODATION
PHYSIOLOGICAL PHARMACOLOGICAL PATHOLOGICAL

23. PHYSIOLOGICAL
PRESBYOPIA :::
 Presbyopia = “old man’s eye”
 It is not an error of refraction but a condition
of physiologic insufficiency of accommodation
leading to a progressive fall in near vision.

24. TYPES OF PRESBYOPIA
INCIPIENT
PRESBYOPIA
FUNCTIONAL
PRESBYOPIA
ABSOLUTE
PRESBYOPIA
PREMATURE
PRESBYOPIA
NOCTURNAL
PRESBYOPIA

25. • (1) incipient presbyopia
 The beginning of presbyopia
 (2)functional presbyopia
 When it disturbs the visual function
 (3)absolute presbyopia
 When no accommodation ability remains

26. • (4) premature presbyopia
At an early age
• (5) nocturnal presbyopia
Decrease amplitude of accommodation in dim
light.

27. SYMPTOM
DIFFICULTY IN NEAR VISION
ASTHENOPIC SYMPTOM
INTERMITTENT DIPLOPIA
TREATMENT
OPTICAL
SURGICAL

28. PATHOLOGICAL ACCOMMODATION
INSUFFICIENCY OF
ACCOMMODATION
ILL – SUSTAINED
ACCOMMODATION
INERTIA OF
ACCOMMODATION
PARALYSIS OF
ACCOMMODATION

29. INSUFFICIENCY OF ACCOMMODATION
• It is used when the accommodative power is
significantly less than the normal physiologic
limits for the patient’s age.
• Can result from systemic conditions such as
diabetes mellitus, multiple sclerosis, anemia,
general physical fatigue, trauma.

30. CLINICAL FEATURES
• Headache & fatigue
• Blurred vision for near
• Irritability of the eye
• Accommodative failure & convergence
insufficiency which may cause intermitted
diplopia

31. TREATMENT
o Treatment of the cause
o Near vision spectacle
o Accommodation exercise

32. ILL SUSTAINED ACCOMMODATION
• It is a condition of accommodation fatigue
refers to a situation in which although the
range of accommodation is normal but cannot
be sustained for a sufficient time period.

33.  CAUSES:
• Asthenopic symptoms
• Ill health
• Uncorrected refractive error
• Over work & emotional stress
 TREATMENT
• Correction of refractive error
• Push-up test
• Distance & near chart exercise

34. ACCOMMODATION INERTIA
• It is a condition in which there is difficulty in
adjusting the accommodation according to the
distance of the object of regard so as to gain
clear vision.

35. TREATMENT
• Correct any refractive error.
• Practise of any accommodation exercise.

36. PARALYSIS OF ACCOMMODATION
• Paralysis of accommodation also known as
cycloplegia refers to complete absence of
accommodation.

40. TREATMENT
• Self recovery occurs in drug induced paralysis
and in diphtheric cases { once the systemic
disease is treated}
• Dark glasses are effecting in reducing glare
• Convex lenses for near vision may be
prescribed if the paralysis is permanent.

41. INCREASED ACCOMMODATION
EXCESSIVE
ACCOMMODATION SPASM OF
ACCOMMODATION

42. EXCESSIVE ACCOMMODATION
• The term excessive accommodation is used to
describe a situation in which an individual
exerts more than normal accommodation for
performing certain near work.

43. CAUSES
 young hypermetropes
Young myopes
Astigmatic error
Presbyopes
Use of improper spectacle

44. CLINICAL FEATURES
• Varying degree of blurred vision due to
induced pseudo myopia
• Asthenopic symptoms
• Both the far point and near point are brought
nearer to the eye

46. TREATMENT
Optical
treatment
General
treatment

48. SPASM OF ACCOMMODATION
• It refers to exertion of abnormally excessive
accommodation which is out of the voluntary
control of the individual.

50. CLINICAL FEATURES
• Varying blurred vision due to induced
pseudomyopia
• Asthenopic symptom
• Headache and browache are typical feature
• Near point is abnormally close

51. TREATMENT
Relaxation of
ciliary muscle
optical
general