accommodation

1. ACCOMMODATION
Presented By…
Biprojit Saha

2. WHATIS ACCOMMODATION?
• It is the ability to see the near object clearly by
increasing the converging power of the eye.
• This is by increasing the refractivity of the lens by
increasing the curvature of its anterior surface.

4. MECHANISM
• CONSTRACTION OF THE CILIARY MUSCLE
• REDUCTION OF CIRCLE FORMED BY CILIARY PROCESSES
• SUSPENSORY LIGGAMENT RELAXES
• ELASTIC CAPSULE OF THE LENS ACTS UNRESTRAINLLY
TO DEFORM THE LENS SUBSTANCE
• LENS THEN ALTERS ITS SHAPE TO BECOME MORE
SPHERICAL

5. mechaniasm

6. FAR POINT, NEAR POINT, RANGE & AMPLITUDE
OF ACCOMMODATION
THE DISTANCE (FARTHEST) POINT
AT WHICH A OBJECT CAN BE SEEN
CLEARLY IS CALLED FAR POINT OR
PUNCTUM REMOTUM.
THE NEAREST POINT AT WHICH A
SMALL OBJECT CAN BE SEEN
CLEARLY IS CALLED NEAR POINT OR
PUNCTUM PROXIMUM.

7. Range& Amplitudeof accommodation
• THE DISTANCE BETWEEN THE NEAR POINT AND
FAR POINT IS CALLED RANGE OF
ACCOMODDATION.
• THE DIFFERENCE BETWEEN THE DIOPTRIC
POWER NEEDED TO FOCUS AT THE NEAR POINT
AND THE FOCUSA AT FAR POINT IS CALLED
AMPLITUDE OF ACCOMODDATION.

8. OCULAR CHANGES IN ACCOMMODATION
• Slackening of the zonules.
• Changes in the curvature of lens surface.
• Bulging of the anterior lens surface.
• Increase axial thickness of lens.
• Slackening of anterior lens capsule.
• Shallow anterior chamber.
• Pupillary constriction and convergence of eyes.
• Forward stretching of choroid.

9. ANOMALIES OF ACCOMMODATION
1.Diminished
• physiological
• Pharmacological
• Pathoiogical:
• 1.Insuffiency .
• 2.Ill-sustained .
• 3.Inertia .
• 4.Paralysis .
2.Increase
• Excessive
• Spasm of accomodation

10. • PRESBYOPIA: THIS IS A PHYSIOLOGICAL
AGEING PROCESS IN WHICH THE NEAR POINT
GRADUALLY RECEDES BEYOND THE NORMAL
REDDING OR WORKING DISTANCE DUE TO
INSUFFIENCY OF ACCOMMODATION.

11. • CAUSES OF PRESBYOPIA:
1. Lens capsule less elastic
2. Lens size increase progressively
3. Weakening of cilliary muscle
A. SYMPTOMS PRESBYOPIA :
• Headache during near work
• Sewing
Optical TREATMENT :
Provide the convex lens. Better to under-correct then
to over-correct

12. ARaughgideforthepresbiopicnearadd
• 45year:+1.00to1.25D
• 50year:+1.50to1.75D
• 55year:+2.00to2.25D
• 60year:+2.50to3.00D

13. • PHARMACOLOGICAL:
Drug induced cyclopiegia result due to effect of
atropine,homatropine,cyclopentolet or other
drug.

14. • INSUFFICIENCYOFACCOMMODATION:Accommodationpowerissignificantlylessthanthe
normalphysiologicallimits.
• ILL-SUSTANDEDACCOMMODATION:Accommodationcannotsustainedfora
sufficienttime.
• ACCOMMODATIVEINERTIA:
Ittakesometimesandsomeefforttofocusnearobjectsafterlookingatadistance.
• PARALYSISOFACCOMMODATION:
 Completeabsenceofaccommodation.
 Itisknownascycloplegia.

15. • EXCESSIVE ACCOMMODATION:
 An individual exerts more than normal accommodation for
performing a certain near work.
• SPASM OF ACCOMMODATION:
 Exertion of abnormally excessive accommodation which is out
of voluntary control of an individual.
INCREASED ACCOMMODATION

16. THANKU...