Glaucoma Flashcards
Ciliary body parts
Pars plicata - anterior. makes aqueous humour, finger like
Pars plana - posterior
Aqueous humour outflow
- Trabecular meshwork and Schlemm’s canal
- Uveoscleral outflow - choroidal and vortex veins
Control of aqueous humour secretion
Symphathetic
beta 2 stimulation - increases secretion
alpha 2 stimulation - decreases secretion
Trabecular meshwork parts
- uveal, inner most, large holes
- Corneoscleral - smaller holes
- Juxtacanalicular meshwork - connect trabecular meshwork with Schlemm canals
Schlemm’s canal
Endothelial lined oval canal - contains holes for channels joining episcleral veins
Iridocorneal angle structures
Glaucoma triad
- raised IOP (not necessary)
- Optic disc changes
- Visual field changes
IOP
Goldmann tonometry
11-21mmHg
high at morning and supine
affected by: CCT, astigmatism and axial length
Neuroretinal rim thickness
ISNT rule
Inferior (thickest)
Superior
Nasal
Temporal (tinnest)
Glaucoma optic disc changes
Neuroretinal rim becomes thin
Optic disc cupping - cup/disc ratio increases >0.3
Visual field testing
Perimetry (Humphry is automated)
Gonioscopy anterior chamber structures
- Posterior corneal surface (Descemet membrane)
- Schwalbe line
- Non pigmented TM
- Pigmented TM
- Scleral spur
- Ciliary body
- Iris
Trabeculotomy
Fistula between anterior chamber and sub-Tenon capsule
Antimetabolites (5FU, mitomycin c) used to prevent bleb failure
Selectiev laser trabeculoplasty
In open angle glaucoma - laser to trabecular meshwork
Frequency doubled Nd:YAG
Peripheral iridotomy
Definitive in closed angle glaucoma
Nd:YAG (1064 nm)
Peripheral iridoplasty
temporary in closed angle glaucoma, burning the iris and pulling it away from TM
Argon (455-529nm)
Causes of post vitreo-retinal surgery glaucoma
- Scleral bukling
- Intraocular gasses
- silicon oil
- Viterectomy
Post cataract surgery glaucoma
inflammation due to leaked visco-elastic material
Ocular HTN
IOP > 21mmHg but no glaucomatous changes
monitor. treat if consistently > 30mmHg
Risk factors for primary open angle glaucoma
- MYOC and OPTN mutations
- Myopia
- Afro-Caribbean
- Age
- smoking and steroids
Primary angle closure glaucoma risk factors
Age
East asian
Hypermetropia (short axial length)
FHx
Pathophysiology of PACG
- Relative pupillary blocl
- Plateau iris (chinese)
PACG mx
Supine, IV acetazolamide, topical timolol
Iridotomy (Nd:YAG)
Past resolved APAC
Descemet folds
Glaukomflecken
Congenital glaucoma
Bilateral, AR
Raised IOP (>12mmHg)
mx
cornea clear - goniotomy
cornea cloudy - trabeculotomy
Features of pigment dispersion syndrome
raised IOP, can lead to glaucomatous changes
- Pigmented TM
- Raised IOP
- mid peripheral spoke like defects on transillumination
- Spindle like pigments on corneal endothelium (Krukenberg spindles)
