Understanding Specular Microscopy.ppt

This presentation explained about specular microscopy for corneal examination in ophthalmology practice. Endothelial counts is important to maintain corneal clarity after cataract surgery using phacoemulsification to remove the cloudy lens.

1. Dr. Johan A. Hutauruk
How to read
SpecularMicroscopy

2. Corneal anatomy
at a glance

3. Descemet’s membrane
Thick basal lamina secreted by endothelium
–Anterior banded 3 μm at birth and stable
–Posterior non-banded 2 μm at birth, increased to 10 μm in adults
•Mainly Type IV collagen, Type VIII and Laminin
•Dua’s Layer
•Just anterior to Descemet's membare
•A very thin and strong layer, 15 microns thick
•Function ?

4. Endothelium
•Single cell, 4-6 mm thick, total 400,000 cells
–At birth :3,500 to 6,000 cell /mm
2
–Adult :1,400 to 2,500 cell /mm
2
•Hexagonal, 20mm wide : amitotic
•Has a single primary cilium : function?
•Large nucleus
•Smolin G, Thoft RA. The Cornea, 3rd Ed. Boston : Little, Brown & Co., 1994

5. Endothelium
•Function :
–Effective barrier from the aqueous
–Maintain metabolic pump
–Maintain corneal transparency

6. Endothelium
Kaufman HE, Barron BA, McDonald MB. The Cornea. New York: Churchil Livingstone 1989

7. Endothelium
•Cytoplasm :
–Numerous mitochondria
–Smooth & rough ER
–Golgi apparatus
•Critical density : Less than 500 cells/mm2
–Not enough room on the lateral cell membrane for the metabolic
pump site corneal edema

8. Endothelium
•Endothelial barrier :
–Permeable
–Tight junction very sensitive to calcium, cause the
junction to break down
–Also regulated by the cytoskeleton (F-action) of
endothelial cells

9. Endothelium
•Endothelial pump :
–Each cell pumps its own value every 5 minutes
–Na
+
K
+
ATPase
•Located in lateral cell membrane
•Glucose fueled
•3 million pump sites per endothelial cells
–Not fluid pump
•Transport ions : Na, bicarbonate from stroma to aqueous
•Water follows passively

10. Smolin G, Thoft RA. The Cornea, 3rd Ed.
Boston : Little, Brown & Co., 1994

11. Endothelium
•Fuchs’ dystrophy :
•Endothelial secrete abnormal collagen
•Endothelial cells stretch
•Permeability increases
–Early stages : normal corneal thickness due to increase pump
rate
–Late stages : corneal edema
•Exhausted Na K pump
•Lateral cell membrane lack of room for additional pump site

12. VISITING PROFESSORSHIP PROGRAM : INASCRS JEC
OPTICAL PRINCIPLE OF SPECULAR MICROSCOPY
▸Light striking a surface :
▸Reflected
▸Transmitted
▸Absorbed
▸Specular microscopy :
▸Light is reflected specularly (mirror-like)
▸Angle of reflection = angle of incidence

13. INTRODUCTION
SPECULAR MICROSCOPE
▸First described by Maurice (1968)
▸Modified by Laing, Bourneand
Kaufman: replacing the original water
immersion lens

14. ORIGINAL ARTICLE

15. CORNEAL
ENDOTHELIAL
CELL
MORPHOLOGY•Cell Area ±S.D. (µm
2
)
•Cell Density (cells / mm
2
)
•Polymegethism (CV)
•Pleomorphism
(% hexagonal 6 sided)

16. Number: the number of analyzed cells
CD : cell density
AVG : Average cell area
SD: standard deviation of cell area
CV : Coefficient of variation of cell area
Max: maximum cell area
Min: minimum cell area
Area: Polymegathism distribution
Apex: Pleomorphism distribution

17. Cell Density
•At birth : 3,000 -4,000 cell /mm
2
•At middle age : 2,500 cell /mm
2
•At old age : 2,000 cell /mm
2
Endothelial cell loss should be biillaterally symmetrical
Difference > 280 cells/mm
2
is clinically significant
Craig T. Use of specular microscopy to
diagnosie corneal disease

18. Cell Density
•Central endothelial cells density decreases 0.6% / year
•Surgical procedures the rate of endothelial cell loss
increases 4 times : 2.5% / year for at almost10 year after surgery
Albon J, Tullo AB, Apoptosis in the endothelium of
human cornea for transplantation. Invest Ophthalmol Vis
Sci 2000; 41: 2887-2893

19. Coefficient of Variation
•Represents the polymegathism
CV increases with increasing SD

20. POLYMEGATHISM
Refers to variation in cell sizes
The first sign of endothelial disease
•Normal young adult 0.27
•CV values 0.32 to 0.40 are elevated
•CV values > 0.40 are abnormal

21. POLYMEGATHISM
CV 45 CD 3268 CV 76 CD 2976 CV 58 CD 3121

22. POLYMORPHISM
Refers to variation in cell shape
Hexagonal shape <
50% is abnormal

23. Fuchs Endothelial Dystrophy
Early stage Moderate Severe

24. ICE Syndrome
ICE cells : large pleomorphic cells with prominent hypereflective nuclei
Liu YK, Wang IJ. Clinical and specular microscopic
manifestation of ICE syndrome. Jpn J Ophthalmol 45. 2001
Dark area with central
spot of light and
peripheral bright zone

25. THANK YOU
For your kind attention