Accommodation is the mechanism by which the eye changes refractive power by altering the shape of lens in order to focus objects at variable distances

1. Presented by :
Dhaneshawar Pal
B. Optometry
5th Semester
Guided by :
Sravani Reddy

2. Introduction
• Accommodation, is the mechanism by which the eye changes
focus from distant to near images, this is produced by a
change in lens shape resulting from the action of the ciliary
muscle on the zonular fibers.

3. FAR AND NEAR POINT OF ACCOMMODATION
• The nearest point at which small objects can be seen
clearly is known as near point of accommodation or
puncutum proximum
• The farthest point at which small objects can be seen clearly
is known as far point of accommodation or puncutum
remotum

4. RECORDING NEAR POINT OF ACCOMMODATION
• The recording of NPA is carried out with a RAF ruler
(Royal Air Force Ruler)

5. POSITION OF FAR POINT & NEAR POINT OF
ACCOMMODATION IN EMMETROPE & AMMETROPE
• Far & near point of
accommodation in
emmetropes :
The far point lies at infinity
The near point varies with
age
• Far & near point of
accommodation in
ammetropes :
In hypermetropic eye
In myopic eye

6. RANGE AND AMPLITUDE OF ACCOMMODATION
• The distance between the near point of accommodation &
far point of accommodation is known as range of
accommodation
• The difference between the dioptric powers needed to
focus at near point & far point is known as amplitude of
accommodation;
• AOA can be calculated as :
A = P - R

7. THEORIES OF ACCOMMODATION
i. HELMHOLTZ THEORY :
Known as “Relaxation Theory”
Also known as “ Capsular Theory”

8. SCHACHAR’S THEORY
• This theory states that accommodation occurs when
ciliary muscle contraction tenses, rather than relaxes the
equatorial zonules

9. THEORY OF INCREASED TENSION
• This theory was given by Tscherning
• This theory attributes to increased curvature of capsule to
tension on zonules;
• It states that contraction of ciliary muscle pull on zonules
directly & increases tension on capsule

10. ANOMALIES OF ACCOMMODATION
• Presbyopia
• Insufficiency of accommodation
• Paralysis of accommodation
• Spsam of accommodation

11. Presbyopia
Insufficiency of
accommodation
• Also known as eye sight of old
age
• This is caused due to decrease
in accommodation power of
crystalline lens with increasing
age
• Loss in accommodation occurs
due to: age related changes in
lens; age-related decline in
ciliary muscles
• Clinical features: blurring of
vision; accommodation
problems; intermediate diplopia
• Treatment: optical treatment,
surgical treatment
• This condition occurs when
the accommodative power
decreases than normal limits
for patients age
• This is caused due to:
premature sclerosis of lens,
weakening of ciliary muscles
• Clinical features: difficulty of
vision at near, intermediate
diplopia, asthenopic
symptoms
• Treatment: optical correction
for near vision,
accommodation exercise

12. Paralysis of
accommodation
Spasm of
accommodation
• Also known as Cycloplegic
• This is caused due to: effect of
atropine, homatropine,
paralysis of ciliary muscles &
sphincter muscles, paralysis of
accommodation
• Clinical features: blurring at
near, photophobia, decreased
rate of range of accommodation
• Treatment: dark glasses,
correction with convex lenses,
self recovery
• Refers to abnormally excess
accommodation
• This is caused due to drug
induced spasm,
spontaneous spasm
• Clinical features: defective
vision asthenopic symptoms
• Treatment: atropine for
relaxing the ciliary muscles

13. OCULAR CHANGES IN ACCOMMODATION
Changes in zonules
Changes in lens
Other changes

14. Reference
• Anatomy & physiology, 3rd edition, Ch. The
crystalline lens, pg. 139-146
• https://www.slideshare.net/RohitRao2/accomm
odation-of-eye