The Coma Flashcards
Arterial supply of the optic nerve
Anterior: Ophthalmic artery to posterior ciliary arteries
Central retinal artery penetrates optic nerve 15 mm behind the globe
Prelaminar: short posterior ciliary arteries and circle of Zinn Haller
Glaucoma risk factors
Age African ancestry Visual field severity Diabetes Disc hemorrhage Follow up IOP Cup to disc ratio CCT PXE Initial IOP Perfusion pressure Hispanic ancestry
Glaucoma Genes
GLC1A (TIGR/MYOC) - 3%
Childhood sporadic risk 2%
CYP1b1 : primary congenital
FOXC1: iridogoniodysgenesis
PITX2: rieger
LOXL1: PXG
Aqueous Humor Outflow
Trabecular Meshwork
Schlemms Canal
Venous plexus
(Uveoscleral pathway)
Active secretion
Ultrafiltration is pressure dependent
Diffusion is based on ions
Goldman Equation
P0 = (F-U) C + Pv
F = aqueous formation
U = pressure independent uveoscleral outflow - 45%
C = pressure dependent TM outflow
* uveal trabecular, corneoscleral, Juxtacanilicular
Pv: Episcleral venous pressure
Fluorophotometry: 2-3 microliters per minute
Visual Fields in specific cases
Early glaucoma affects M cells - FDT and FDF
SWAP targets the small bistratified ganglion cells
Collaborative Normal Tension Glaucoma Study
IOP lowering by 30% reduced the 5 year risk of visual progression from 35 % to 12%
Low Pressure Glaucoma Treatment Study
High rate of glaucomatous progression in those treated with timolol - with a grain of salt as high attrition
Collaborative Initial Glaucoma Treatment Study (CIGTS)
Visual Field defects are 7 times more likely to progress in patients 60 years or older than in those younger than 40 years
Newly diagnosed glaucoma to trab vs meds , similar firms progression
Ways iris can be pushed forward from behind
Pupillary block Aqueous misdirection Ciliary body swelling, inflammation or cysts Plateau iris configuration Chorodial swelling Posterior segment tumor or space occupying lesion Contracture of retrolental tissue Anterior lens Sclera buckle
Iris is pulled forward
Contraction of inflammatory membrane ICE fibrous ingrowth Epithelial ingrowth Iris incarceration
Anesthetics and IOP
Most of them lower IOP
Chloral Hydrate doesn’t effect it
Ketamine increases it
Prostaglandin Analogues
Prodrug that is activated by cornea esterase (except bitmatoprost)
Increase outflow via uveoscleral pathway by remodeling
Less effective when used twice daily
Increased number of melanosomes within melanocytes
Periorbitopathy: due to fat atrophy
Beta antagonist
Inhibit cAMP and reduce aqueous humor secretion , can get contralateral lowering
Alpha agonist
NoNselective : epinephrine and dipivefrin reduce aqueous humor production, increase outflow
Alpha2 selective - reduce aqueous humor production due to inhibitory G protein
A1 activity results in conjunctival vasoconstriction, pupillary dilation, eyelid retraction
