SPECIAL LENSES Flashcards by Eve Buesnel | Brainscape

Q

Options for underwater use

A

modular rx goggles
full Rx goggles
plastic insert for diving mask
flat form glass lenses bonded to mask

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Q

Optical principals for lenses underwater

A

plano front to maintain BVD
n=1.333 meaning increased image size by 33%
BSEN 2738 (full Rx may be incorporated)
BSV = sphere + 1/2cyl
CD’s can’t be specified

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Q

Recumbent prism

A

used to rotate field through 90 degrees
used by bedridden patients / climbers / someone with a stoop

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Q

Optical principals of recumbent prisms

A

silvered prisms where light is reflected twice and emerges through the third surface

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Q

Fresnel prism

A

high powered prism correction
temporary/ short term
cheap
light weight
not cosmetically appealing

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Q

Optical principals of fresnels

A

1mm sheet of PVC
small parallel prisms
up to 40 diopters
reduce acuity by 2 lines

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Q

Ptosis props

A

projects to sit under brow to maintain eyelid position
bar / loop fitted to back of frame

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