1. Pathogenesis of Glaucoma Translaminar-pressure difference
부천 성모병원 안과 홍승우

2. Pathogenesis of Glaucoma Conventional concepts
The Mechanical Hypothesis
Glaucoma is fundamentally caused by intraocular pressure deforming the optic nerve head and lamina cribrosa
The Vascular Hypothesis
Elevated intraocular pressure alters the blood flow within the optic-nerve head

3. Definition of Glaucoma
The definition of Glaucoma is any ocular disease that will cause characteristic optic neuropathy or optic nerve damage which may result in progressive visual field loss and it can be associated with either normal or abnormal intraocular pressure. Abnormal intraocular pressure can be high or low

4. Characteristic optic neuropathy or optic nerve damage
Characteristic of glaucomatous field defect
Progressive field defect
Never cross horizontal merdian
Sectoral field defects correspond to RNFL defects
* Glaucoma – Optic neuropathy or optic nerve damage occurs within the lamina cribrosa level

5. Pathogenesis of Glaucoma Conventional concepts
The Mechanical Hypothesis
It itself can not explain the characteristic glaucomatous damage
Focused investigation
Structural Properties of Lamina cribrosa
The Vascular Hypothesis
Except arteritic AION, vascular occlusive diseases which even occurs within the lamina cribrosa do not represent glaucomatous damage
- Properties of Microvasculature of Lamina cribrosa

6. Pathogenesis of Glaucoma Translaminar pressure difference
Optic nerve fiber (Retinal ganglion cell)
Lies in 2 pressurized compartment
Intraocular space and subarachnoid space
- Endure pressure gradient
Peripheral nerve
Can tolerate high pressure up to 3800mmHg
However, pressure gradients significantly reduce rapid orthograde axonal transport

7. Pathogenesis of Glaucoma Translaminar pressure difference
Axonal transport
Pressure gradient
4.5mmHg/100um (46mmHg/mm)
Rapid axonal transport is inhibited

8. Pathogenesis of Glaucoma Translaminar pressure difference
Axonal transport in animal glaucoma model

9. Pathogenesis of Glaucoma Translaminar pressure difference
11-21mmHg
(Sitting position)
5 to 15mmHg
(Supine Position)

10. Pathogenesis of Glaucoma Translaminar pressure difference
Translaminar Pressure Gradient
(IOP-intracranial pres.)
/Depth of Lamina Cribrosa
At IOP 15mmHg, ICP 0mmHg, Depth of Lamina Cribrosa 500um
= 30mmHg/mm

11. Pathogenesis of Glaucoma Translaminar pressure difference
POAG
High IOP, Low CSF pressure
NTG
Low CSF pressure
High glaucoma prevalence in Myopic Pt.
Thin Lamina cribrosa
OHT
High CSF pressure

12. Translaminar pressure difference Animal Model
1979 Yablonski ME
Settings
Cats
Negative CSF pressure (-4mmHg)
One eye – Zero IOP
The other eye – no intervention
After 3 weeks unchanged eyes developed glaucomatous damage

13. Cerebrospinal Pressure
* In animal model, ON subarachnoid spaces secure their space when CSF pressure drops below zero.
CSF Pressure at Brain
0 to -1 mmHg
CSF Pressure at Lumbar Puncture site
8 to 15mmHg
CSF Pressure at Lower Spine
60 mmHg

14. Translaminar pressure difference Limitations
Normal Tension Glaucoma
Normal subarachnoid pressure of optic nerve (0 to -1mmHg)
Subarachnoid pressure can be substantially low in NTG patient?
NTG patients showed larger subarachnoid space in optic nerve in radiologic studies
Glaucoma prevalence in Myopic Pt.
Glaucoma prevalence is not so high in myopic Pt. considering lamina cribrosa thickness
OHT
Subarachoid pressure can be substatially High in OHT patient?

15. Pathogenesis of Glaucoma Translaminar pressure difference
Lamina cribrosa

16. Pathogenesis of Glaucoma Translaminar pressure difference
* Orbital space (Pressure)
CSF pressure
Intraocular Pressure
Pia mata
Structures of Subarachnoid space