LENS & CATARACT
Prof. Naimatullah Khan Kundi
Head, Department of Ophthalmology
Khyber Teaching Hospital
Peshawar
Lens
 Crystalline Lens
 Position behind the iris
 Refract light rays
 Focuses on the retina
Lens
 Functions







Maintains its own clarity
Provides refractive power (by contributing
to the optical system of ...
Lens
 Aphakia – absence of the lens
 Results in loss of 20 D of refractive

power
 A vascular – Obtains nutrition from ...
Lens
 Biconvex
 Anterior Pole – The most anterior part
 Posterior Pole – The most posterior part
 Equator – The periph...
Lens & Cataract

Anatomy

 Normal Crystalline Lens


Transparent , Biconvex, Avascular



Refractive Power:



Axis: I...
Lens & Cataract

Anatomy

 Normal Crystalline Lens (Cont’d)


Zonular Fibers: From CB to Lens (Ant. & Post.)



Capsule...
Lens & Cataract

Anatomy

 Normal Crystalline Lens (Cont’d)


Older lens:
 More Curved – More refractive power
 Refrac...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Lens Capsule


Elastic, Transparent,



BM (Type IV Collagen, Laid...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Lens Capsule


Thickest regions:

Ant. & Post. Pre-equatorial zones...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Zonular Fibers


Support the lens



Origin: Basal lamina of non-p...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Lens Epithelium
 A single layer beneath the anterior lens capsule
...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Lens Epithelium
 Newly formed lens cells migrate toward equator 
...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Lens Epithelium
 The cells loose organells (mitochondria, nuclei,
r...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Nucleus & Cortex
 New lens fibers laid down through out the life
 ...
Lens & Cataract
 Normal Crystalline
Lens
 Nucleus & Cortex
 Lens sutures (anterior
and posterior “Y”)

 Formed by
inte...
Lens & Cataract

Anatomy

 Normal Crystalline Lens
 Nucleus & Cortex
 SL biomicroscopy
 Shows multiple optical zones, ...
Anatomy  of EYE
Anatomy  of EYE
Anatomy  of EYE
Anatomy  of EYE
Anatomy  of EYE
Upcoming SlideShare
Loading in …5
×

Anatomy of EYE

764 views

Published on

This presentation is orginaly uploaded to http://kpkmedicalcolleges.tk by Dr.Suleman

Published in: Health & Medicine, Business
0 Comments
1 Like
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
764
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
22
Comments
0
Likes
1
Embeds 0
No embeds

No notes for slide

Anatomy of EYE

  1. 1. LENS & CATARACT Prof. Naimatullah Khan Kundi Head, Department of Ophthalmology Khyber Teaching Hospital Peshawar
  2. 2. Lens  Crystalline Lens  Position behind the iris  Refract light rays  Focuses on the retina
  3. 3. Lens  Functions     Maintains its own clarity Provides refractive power (by contributing to the optical system of the eye) Provides accommodation - Allows the eye to clearly focus objects (within a 6 m range) Absorbs UV light
  4. 4. Lens  Aphakia – absence of the lens  Results in loss of 20 D of refractive power  A vascular – Obtains nutrition from the surrounding fluids  Glucose – provides the lens with chemical energy required to continue growth and maintain transparency
  5. 5. Lens  Biconvex  Anterior Pole – The most anterior part  Posterior Pole – The most posterior part  Equator – The peripheral area
  6. 6. Lens & Cataract Anatomy  Normal Crystalline Lens  Transparent , Biconvex, Avascular  Refractive Power:  Axis: Imaginary line between Ant. & Post. 15-20 of convergence Poles of the lens  Equater: Greatest circuference  Meridians: Lines on the surface from one pole to the other
  7. 7. Lens & Cataract Anatomy  Normal Crystalline Lens (Cont’d)  Zonular Fibers: From CB to Lens (Ant. & Post.)  Capsule: BM that Encloses the nucleus, Cortex and Lens epithelium  Growth: Grows Continuously through life  At birth: Wt. 90mg, AP – 3.5 mm, Equatorially – 3.5mm  Adult: Wt. 225 mg, AP – 5 mm, Equatorially – 9mm
  8. 8. Lens & Cataract Anatomy  Normal Crystalline Lens (Cont’d)  Older lens:  More Curved – More refractive power  Refractive index decrease with age (? Increased insoluble proteins)  Eye – Hyperopic / Myopic with age depending upon the balance of these opposing changes
  9. 9. Lens & Cataract Anatomy  Normal Crystalline Lens  Lens Capsule  Elastic, Transparent,  BM (Type IV Collagen, Laid down by epithelial cells)  Moulds the lens substance during the accommodative changes  Outer layer (zonular lamella) serves as the point of attachment of zonular fibers
  10. 10. Lens & Cataract Anatomy  Normal Crystalline Lens  Lens Capsule  Thickest regions: Ant. & Post. Pre-equatorial zones  Thinnest regions: Central Post. Pole (2-4µ m)
  11. 11. Lens & Cataract Anatomy  Normal Crystalline Lens  Zonular Fibers  Support the lens  Origin: Basal lamina of non-pigmented epithelium of Pars Plana & Pars Plicata of CB  Insertion: Equatorial region 1.5 mm onto Ant. & Post. Capsule  Equatorial zonular fibers regress with age, leaving triangular area
  12. 12. Lens & Cataract Anatomy  Normal Crystalline Lens  Lens Epithelium  A single layer beneath the anterior lens capsule  Active metabolically
  13. 13. Lens & Cataract Anatomy  Normal Crystalline Lens  Lens Epithelium  Newly formed lens cells migrate toward equator   Change to lens fibers  In the bow region begins the process of terminal differentiation into lens fibers
  14. 14. Lens & Cataract Anatomy  Normal Crystalline Lens  Lens Epithelium  The cells loose organells (mitochondria, nuclei, ribosomes)  Lens fibers dependent on glycolysis for energy production  Advantage: No light absorption/scatter
  15. 15. Lens & Cataract Anatomy  Normal Crystalline Lens  Nucleus & Cortex  New lens fibers laid down through out the life  Thus crowding and compression of older fibers  Embryonic and fetal nuclei oldest  Outer most fibers recent (cortex)
  16. 16. Lens & Cataract  Normal Crystalline Lens  Nucleus & Cortex  Lens sutures (anterior and posterior “Y”)  Formed by interdigitations of apical and basal cell process Anatomy
  17. 17. Lens & Cataract Anatomy  Normal Crystalline Lens  Nucleus & Cortex  SL biomicroscopy  Shows multiple optical zones, having different optical densities  Nucleus, epinucleues, Cortex

×