Ultrasound and glaucoma

Cyclic sound pressure with a frequency greater than the upper limit of human hearing

Amplitude of echo spike over time

Ultrasound signal used to produce various points whose brightness depends on amplitude instead of the spiking vertical movements in A mode

• Axial length (primary and secondary iol)
• opaque media (hyphema, cataract, vitreous debris)
• trauma (posterior rupture of globe, no scan is sidel positive)
• pediatric cases (fundus view, leukocoria)

0.449mm

4.979 mm

2.794 mm

Between 2 and 50MHz

Amplitude mode

Brightness mode

Orbital fat

Optic nerve

Aging causes liquefaction of vitreous gel - low reflective

Calcium soaps - highly reflective dot like interfaces - usually with anechoic band

Less mobile than vitreous membrane

Contour smooth to globe, annular appearance within the anterior aspect of the globe is effusion with diffuse thickening posterior pole

Most common primary lesion of globe, single lesion, RD

Color or grey scale high resolution images of layers of retina,

Volume measurements of the macular region

A group of disorders that result in damage to the optic nerve and vision loss.

African Americans, age, elevated iop, family history

Rate of aqueous humor production, resistance to aqueous outflow, episcleral venous pressure

Juxtacanilicular

Shallow ant. Chamber, pupillary block, increased pressure in post chamber, Iris bomb'e, damage to lens epithelim, minute ant sub caps opacification, corneal edema

Trauma, inflammation, tumor or malformation, chronic retinal ischemia and increased VEGF, necrotic tumor, iridocorneal endothelial syndrome, episode down growth, cilliary body tumor

P=F/A. Pressure in sphere equals the force necessary to flatten its surface divided by the area flattened

Arcuate, superior, paracentral, seidel scotoma, complete arcuate, sup/inf arcuate, superior nasal step, vertical step

Swedish interactive threshold algorithm

<33%

<20%

Difference between measured threshold for each retinal point and age corrected normal

Total deviation adjusted to equal an average of the 17 worse test points, eliminating background noise like cataract

Measures localized defects and how they deviate from age corrected normals

Scanning laser polarimetry measures peripapillary RNFL, cell axons in retina cause polarization of light

Depicts different thicknesses of peripapillary RNFL

3.4 mm measuring RNFL

Time domain 5 micron

Fourier. Domain 2 microns

Confocal scanning laser, principle of spot illumination and spot detection.

Miotics, beta-blockers, alpha-agonists, carbonic anhydrase inhibitors, prostaglandin analogs

Argon laser trabeculoplasty, selective laser trabeculoplasty

Pigment dispersion, pseudoexfoliation, non compliant, allergic, what iop drop would you expect? How long does it last?

Trab, trab with express mini shunt, Ahmed valve, baerveldt valve, trabectome, canaloplasty, edocyclophotocoagulation, trans-scleral cyclophotocoagulation

Endocyclophotocoagulation

Trans-scleral cyclophotocoagulation