A humble effort to present a brief yet comprehensive and illustrative description of one of the most delicate albeit amazingly balanced finesse perfected by mother nature herself, working right within our very own eyes, that is the Aqueous Humor.

1. Aqueous Humour
Dynamics
- Vaibhav Shriya
VI Sem.

2. Introduction
• Aqueous Humour – watery fluid
• Properties – Volume, pH,
Specific gravity, osmolarity,
refractive index

3. Applied Anatomy
• Ciliary Body – continuation of choroid, 5
layers, processes (70-80, 2mm, 0.5mm dia.,
core)
• Irido-corneal Angle –aka???; Root of Iris,
Anterior part of ciliary process, Scleral spur,
TM, Schwalbe’s Line
• Outflow system – TM {Uveal,
Corneoscleral, Juxtacanalicular), Schlemm’s
Canal, Collector channels (plexus + aq. V.)

6. 1) Perf. Br. Of Ant. Cil. A.; (2) MjAC of iris; (3) First Vasc.
Territory; (4a) Second Vasc. Territory {Marginal Route}; (4b)
{Capillary Network in center of territory}; (5) Third Vasc.
Territory; (6)(7) Aa. To Ciliary mm.; (8) Recurr. Choroidal aa.

7. Applied Physiology
• Formation – Rate (formn., excretion diff. 1-1.5% of rate)
1. Ultrafilteration (15%): Hydrostatic Pressure, BCOP; BP
fluctuation
2. Active secretion (80%): BAB; Zona Occludens (IMW, HMW
molecules  Glucose, Urea, Protein); systemic BP effects (-);
Na+-K+-ATPase & CA (CA-II, CA-IV), HCO3
- is main
3. Diffusion (5%): D/t active secretion
**(1) and (3) form reservoir  (2)
• Control of Aqueous formation –
1. Diurnal variation (3-6 mm Hg/day; >8mm  Glaucoma?; peak
in morning, repeated evaluation to avoid misreading); p.
cortisol
2. ADH, adenyl cyclase (affect Na+ active transport)

9. Stimuli that Break BAB

10. • Functions of Aqueous – IOP (normal?),
Metabolic & Nutritional, Transparency, Clearing
• Composition – Water (99.9%), Protein (5-16
mg%) {iridocyclitis}, amino acid (5 mg/kg), non-
colloids in mmol/kg {Glucose (6), urea (7),
ascorbate (0.9), lactate (7.4), inositol (0.1), Na+
(144), K+ (4.5), Cl- (10), HCO3
- (34), oxygen
dissolved
• Difference between anterior & posterior
chamber aqueous humour –
higher HCO3
- , lactate, pyruvate, ascorbate
(Vit. C) ??; lower chlorine

11. Drainage of Aqueous Humour
• 2 pathways – CONVENTIONAL/ Trabecular,
UNCONVENTIONAL/ Uveoscleral
1) Conventional – 80%, TM (Juxtacanalicular resistance)
 SC  episcleral & Conjunctival vv., Vacoulation Theory

14. • Conventional – Biomechanical/ Active pump
mechanism (Cardiac diastole  low BP in choroid
vessels  TM retracted in  negative pressure in SC,
aqueous valves open  aqueous flows in SC 
systole…); IOP = 15 mm Hg, Pe = 10mm Hg {MoA}

15. 2) Unconventional – 20%; aqueous exits via root
of iris, ciliary body base, uveal TM elastic tissue
between ciliary muscles  Suprachoroidal lamina
 scleral tissue; decreased with cholinomimetics,
age (thickened elastic tissue between ciliary
muscles), PG’s
** UVEOVORTEX pathway – unconventional;
passive process; confirmed by Tracer studies;
Tracer crosses vessels of iris, ciliary muscles,
anterior choroid, reaches Vortex v.
• Intrascleral vv. – 2 types { aqueous vv. (larger
caliber, shorter course, less number); intrascleral
plexus (opposite)}  Episcleral & Conjunctival vv.

16. IOP Maintenance
A. Local factors :
1.Rate of aqueous formation (permeability of
ciliary capilaries, BCOP)
2.Resistance to aqueous drainage (mostly at
TM)
3.Raised Pe (Valsalva’s manoeuvre)
4.Pupil dilation (with narrow iridocorneal angle
 reduced drainage)
5.Errors of refraction (raised in MYOPIA)

17. B.General factors
1.Heredity (Enlarged CDR (Cup to Disk Ratio),
relatives having open angle glaucoma)
2.Age (after 40’s d/t reduced outflow)
3.Gender (Increase with age in females)
4.Diurnal variation (3-6 mm Hg/day; >8mm 
Glaucoma?; peak in morning, repeated
evaluation to avoid misreading); p. cortisol
correlation
5.Postural Variation (sit  supine  increase by
0.3-6 mm Hg)
6.Seasonal Variation ( more in winter d/t lower
Pe)

18. 7. BP (HTN is P/F for glaucoma)
8. BCOP {rise (i.v mannitol 20%, uraemia, oral
glycerol)  low IOP; fall (water drinking
provocative test)  raised IOP}
9. Others ( Raised IOP  caffeine, smokers, LSD,
steroids; Low IOP  Heroin, marijuana,
alcohol, low fat diet)
10. Exercise ( Low IOP  strenous exercise)
11. GA {Raises IOP  GA in child, muscle
relaxants, tracheal intubation, raised pCO2 , low
O2; Lowers IOP  GA, Hypnotics}

19. MCQ’s

20. Thank You