Accommodation is the ability of the eye to focus on near objects by increasing the curvature of the lens. It occurs through contraction of the ciliary muscle which relaxes the suspensory ligaments, allowing the elastic lens to bulge and become more spherical. The range of accommodation is the distance between the near and far points, while the amplitude is the dioptric difference needed for focus. Presbyopia occurs due to weakening of the ciliary muscle with age, decreasing the near point. Treatment involves convex lenses to compensate. Other anomalies include diminished accommodation from aging, drugs, or pathology, as well as increased accommodation from spasm.

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...