Objective 3 Flashcards
What is cobalt Blue (Ultra violet ) filter used for?
In conjunction with sodium fluorescein dye.
What does the blue filter do to the fluorescein ?
Excites the fluorescein causing it to take on a greenish hue which is visable to the observer.
What is the Red Free (green) filter used for?
To view neovascularization and for fundus observations.
How does the Red Free (green) filter work?
The green filter removes red from the view and consquently blood vessels look black. This makes the blood vessels stand out and makes them more easily identifiable.
What is the Yellow Filter/ Wratten Filter#12 used for?
The yellow/wratten filter is used in conjunction with a cobalt blue filter and fluorescein to enhance the pattern behind a GP contact lens containing a UV filter.
The Yellow Wratten filter is used differently than the other filters, how?
This filter is placed in front of the observation system, not the illumination system.
What is a Diffuser (filter) used for?
This filter is like uncolored pebbled glass. The light passing through it is diffused and therefore more comfortable for the patient.
What is a Polarizing Filter used for ?
These prevent the passing of light from a specific angle and are used for tear film evaluation and some cataract assessments.
What is Fluorescein used for ?
To observe areas of roughened or absent epithelium. Helpful in locating: abrasions, corneal injuries, dryness, tears. Used with Tear break up time and assessing the fit of rigid contact lenses.
What is the best form of Fluorescein to use?
The paper strips are prefered over the liquid preparations as they can be easily contaminated.
How do you use the fluorescein strips?
Wet strip with sterile saline solution, ask px to look up, retract the lower lid, apply the orange end of the wet strip to the inferior palpebral conjunctiva, avoid contact with the cornea, ask px to blink two or three times, use cobalt blue filter on the biomicroscope for examination.
Alterative: Px looks down, grasp upper lashes, apply to superior bulbar conjunctiva.
How is Rose Bengal used?
Used in conjunction with the slit lamp, it stains the mucus and dead cells magenta.
Will cause stinging, use small amount touched on the bulbar conjunctiva and then rinse away with steril saline.
Will show smaller areas of irritiation than fluorescein, and does NOT need a filter for viewing.
How is Listhamine Green used?
The same as Rose Bengal without the stinging.
