cataract. etiopathogenesis and lens anatomy

2. What is cataract???
What is the need to know
about it ?????????

3. 62.6%
“BURDEN OF
CATARACT “

4. Global urban blindness
- 50 million in 2000
Will grow to
- 75 million by 2020
unless special efforts
to arrest / reverse this

5. THIS BURDEN IS
HEAVIER FOR A
DEVELOPING COUNTRY
LIKE OURS
WHYYY???????

6. poor uptake of
services due to llack
Projected in population of pt information
the burden becomes heavier
in our countryOccurs a decade earlier
life expectancy

7. TREATABLE
CAUSE
OF BLINDNESS
•

8. VISION 2020 - RIGHT TO SIGHT

9. ANATOMY – LENS
&
ETIOPATHOGENESIS OF CATARACT

12. Who said ……..
“ UNION IS AN ONION “
We can say…….
“ LENS IS AN ONION “

14. A
REGULAR
RECORD OF
OUR AGE !!!
zonules

15. Do you know…!!!!!!!!!…
organ that grows through out life..???
Thickest basement membrane in our
body..??
Least hydrated organ in our body…??
Structure with Highest protein
content…….??
Blood supply of lens………. ??

16. CAPSULE :
BY THE – Lens Epithelium
FOR THE – Accommodation
OF THE - Type 4 collagen
Capsule arround the lens is not uniform in thickness !!
Thickest - para equatorial region
Thinnest - at poles
esp posterior pole

17. THICKNESS OF CAPSULE AT VARIOUS PARTS :-

18. EPETHELIUM :
single layer of epithelium just beneath the ant. capsule
, it forms
Capsule
Lens fibers (ant. Preequatorial region)
That’s why,
Oldest lens fibers are - Deepest
Oldest capsule is - Most superficial
EPETHELIUM :
single layer of epithelium just beneath the ant. capsule
, it forms
Capsule
Lens fibers (ant. Preequatorial region)
That’s why,
Oldest lens fibers are - Deepest
Oldest capsule is - Most superficial
EPETHELIUM :
single layer of epithelium just beneath the ant. capsule
, it forms
Capsule
Lens fibers (ant. Preequatorial region)
That’s why,
Oldest lens fibers are - Deepest
Oldest capsule is - Most superficial
EPITHELIUM :
single layer of epithelium just beneath the ant. capsule
, it forms
Capsule - anteriorly
Lens fibers - posteriorly
(ant. Preequatorial region)
That’s why,
Oldest lens fibers are - Deepest
Oldest capsule is - Most superficial

19. Post.capsule
Epithelium Cortex
Ant.capsule Nucleus
epithelium maturing
to lens fiber
ANTERIOR POSTERIOR
ANTERIOR POSTERIOR

20. CORTEX & NUCLEUS:
 No cells (lens fibers) are lost
 As new fibers laid down – it crowds &
compacts the previously formed fibers
thus……., Center to periphery
embryonic nuclei
fetal nuclei
infantile nuclei
adult nuclei
cortex
BUT SURGICAL NUCLEUS & CORTEX????

21. As you travel from capsule towards nucleus
through LENS
Age of fiber
Density
Protein conc.
Enzyme conc.
Glutathione
O2 Conc.

22. Na+
K+
Amino acid
Inositol
Ca2+
Glucose
LACTIC ACID
Active
Passive
NOTE :
O2 not allowed into the
lens
Lactic acid from anaerobic
metabolism –high conc.
With in lens , so passively
diffuses out
Aqueous is the only
source of glucose,so it
passively diffuses in

23. GLUCOSE
G – 6 – P
Triose – P
Pyruvate
Sorbital
Fructose
POLYOL PATHWAY
CO2 + Acetyl CoA
KREB’S
CYCLE
CO2 CO2
NADP GSH
HMP Path (15%)
NADPH GSSG
Pentoses
Lactate
GLYCOLYSIS (50%)
(Anerobic)
Aldose
reductase

24. Reactive O2 species :-
superoxide O 2
-
H2O2 Hydroxyl ion.OH -
Inflamation Mitochondrial e-
transport chain
2O2
-
+ 2H+
SOD
H2O2
GPX GSH
At cytoplasm
2 H2O
(HMP) NADPH GSSG PSH
GR TT
NADP GSH PSSG
Fenton’s reaction
At cell membrane
Catalase
H2O + ½ O2

25. LENS OPACITY
Capable of causing
some visual loss,
measured as acuity
loss
FUNCTIONAL
CATARACT:
Len opacity causing
visual loss sufficient to
produce functional
disability

26. CONGENITAL
METABOLIC
ACQUIRED
TRAUMATIC
COMPLICATED
TOXIC
SENILE
INFECTIOUS
DIABETICMETABOLIC

27. Most common type of cataract,
Out of people aged bt,
52 – 64 yrs 4.6 %
65 – 74 yrs 18 % are with
75 – 85 yrs 46 % cataract

28. CATARACT IS ALWAYS,
But 3 mechanisms of great importance :-
OXIDATIVE STRESS
PHOTOOXIDATION
GLYCATION

29. 2O-
2 + 2H+
SOD
H2O2
GPX GSH
H2O
GSSG
HMP NADPH PSH FREE
RADICAL
GR TT
NADP GSH PSSG
2
1 2
1
2
3
GSH
with aging Deterioration of mech. that protect
against oxidative damage

30. CHROMOPHORE ????
Proteins & DNA are the chromophores in
lens
LIGHTS ABSORBED,
UVA
UVB
VISIBLE LIGHT
All cells of our body are equally exposed to
Light but why damage specifically occur in
Lens…??????????

31. CHROMOPHORE
Direct photochemical Photosensitised
chemically changed chemically unchanged bt
chromophore can cause it in another
molecule
eg. tryptophan
free radicals

32. LYCATION a condensation reaction bt
amino grp of protiens &reducing sugars
GLYCATING AGENTS :-
GLUCOSE
G – 6 – P
Ribose
DHA (Oxidised ASA)
DIABETIC

33. Protien – NH2 + Glucose
EG Pdt (MORE IN CORTEX)
AGE Pdt (MORE IN NUCLEUS)
Crosslinking with protiens
conformational change
aggregation
Brown
Pigmentation

35. To summaries as we grow older…….
 Mitochondrial func.
 Superoxide
production
 Loss of UV filters in nucleus
 UV absorption
 Photosensitisers
 Total no: of photons absorbed
 Every 5 th person
visiting a physician is
diabetic
 Amount of AGEs
 CORTEX – NUCLEUS
interface develops

36. INDIA - DIABETIC CAPITAL OF THE WORLD
11.6% of urban indians are diabetic
3 to 4 fold increase in incidence of cataract in
diabetic pts under 65 yrs,
High Diabetic age
Poor control
Invites cataract earlier

37. Do You Think A Person Above 50 Is Going
To come With Problem of cataract
Alone…….??????
CATARACT is always MULTIFACTORIAL

38. GSH PROTEIN MODIFICATION CATARACT
↓ GSH
↓Free a.a
↓Protein syn.
loss of enzymes
↓Glycolysis
↓ ATP
DIABETES
↑Glucose Sorbital
↓NADPH ↑G-6-P fructose
PROTEIN MODIFICATION
Croslinkng bt proteins
Aggregation of proteins
Na+-K+ ATPase
Ionic imbalance
↑Ca2+ osm shock
proteolysis

39. Malnutrition
DIARRHOEA FAILURE
↑ Urea
↑ Cyanate
STEROID
↑Glucose Sorbital
↓NADPH ↑G-6-P fructose
↓ GSH PROTEIN MODIFICATION
Croslinkng bt proteins
Aggregation of proteins
Ionic imbalance
OTHER FACTOR INFLUENCING CATARACT :-

40. CONGENITAL
ACQUIRED
METABOLIC
TRAUMATIC
COMPLICATED
TOXIC
SENILE
INFECTIOUS
14% Of all cases of childhood blindness
20% - RUBELLA
20% - HEREDITARY . DOMINANT
6% - WITH OCCULAR ANOMALIES
35-50% - SPORADIC
5 % EACH

41. 
TAKE HOME……
Senile Cataract Is always
multifactorial….
Poor control &
high diabetic age…..
Congenital cataract –
rubella,again is preventable
Public education- can result better
utility of services

42. And…