Retro illumination

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RETRO-ILLUMINATION Manahan, Maclester T. OP 1-1

description

retro-illumination

Transcript of Retro illumination

Page 1: Retro illumination

RETRO-ILLUMINATIONManahan, Maclester T. OP 1-1

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Retro-illuminationObject of interest is illuminated only by light

reflected from the structures behind it.

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Vary angle of illumination

Moderately wide beam

Slit beam is offset

Medium to high magnification

Reflected light from iris or fundus

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Objectives1. Assessment of pupils and all parts of the transparent ocular media (tear film, cornea, aqueous, lens, and vitreous). 2. Used to observe whether the opacity is -Obstructive – Opaque to light-Respersive – Scatters light-Refractile – Refracts, minimizes or distorts the views of background.3. Observe anterior capsular changes -Deposits, Foreign bodies, Opacities Below Capsule.

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Procedure

direct retro-illumination: The observed feature on the cornea is viewed in the direct pathway of reflected light. The angle between the microscope and the illuminating arm is about 60°.indirect retro-illumination: The angle between the microscope and slit-lamp arms is greatly reduced or increased so that the feature on the cornea is viewed against a dark background. It may be necessary to uncouple the beam.

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Alignment of reflected beam with area under observation

TYPE ALIGNMENT

Direct Direct and full view

Indirect Adjacent

Marginal Margin or edge

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Direct Retro-illumination

Look to the side of the corneal blockObjects viewed may have one color in direct and

a different color with retroillumination.

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The object (observed structure) is viewed in the direct pathway of the reflected light. The illuminated background is directly behind the observed structure.

direct retro-illumination

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Indirect Retro-illumination

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The object (observed structure) is not viewed in the direct pathway of the reflected light. The retro-illumination object is viewed against a dark non-illuminated background. The reflecting illuminated surface is to one side of the axis of observation.

observed structure

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observing:VascularizationEpithelial oedemaMicrocystsVacuolesDystrophiesCrystalline lens opacitiesContact lens deposits

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Limbal InjectionLimbal vessel engorgement seen with retro-illumination and very high magnification. This may be a prelude to vascularization.

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VascularizationVascular ingrowth into the cornea arising from a vaso-proliferative stimulus..Observe the looping and branching limbal vessels seen against the illuminated background of the clear cornea.

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Jelly BumpsLipoidal deposition on the lens surface, common with high water content hydrogel lenses.

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findings:Expectedabsence of:

VascularizationEpithelial oedemaMicrocystsVacuolesBullaeDystrophiesCrystalline lens opacitiesContact lens deposits

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