L1 Flashcards
(20 cards)
Why can’t we see a persons retina normally
Because the observers eyes block the rays of light that illuminate the part of the retina they are trying to see
What 2 systems must an ophthalmoscope have
An illuminating and viewing system
How does the ophthalmoscope help to view the retina
It illuminates the retina where the observer normally gets in the way
What are the 3 things that must happen during ophthalmoscopy
- The fundus must be illuminated
- The light reflecting from the fundus has to enter the examiners eye
- There has to be an optical system for focusing the light from the patients eye onto the examiners retina
During indirect ophthalmoscopy what does the condensing lens do to the image
It it inverts and reverses the image
What does slit lamp indirect ophthalmoscopy allow?
Binocular viewing of the fundus with stereoscopic examination, using a slit lamp and condensing lenses to form an aerial image.
Why is additional magnification needed in slit lamp indirect ophthalmoscopy?
Because the high-powered condensing lenses provide low magnification.
What is the observation system in a slit lamp?
A binocular system with variable magnification, which can be adjusted by changing eyepieces or objectives.
What is the advantage of a zoom (continuous magnification) system in a slit lamp?
Easy for maintaining focus, though more expensive.
How should eyepieces be set to avoid eyestrain?
Slightly convergent and adjustable for pupillary distance and refractive error.
What is the illumination arm in a slit lamp?
A short focus projector with a slit aperture, allowing variable light intensity, filters, slit width, slit height, and angle of illumination.
What filters may be present on a slit lamp?
Diffuser, heat reduction, neutral density, polarising, red free, cobalt blue.
How is slit beam height controlled in Haagstreit and Zeiss systems?
Haagstreit: top of illumination arm; Zeiss: bottom of illumination arm.
How is slit beam width controlled in Haagstreit and Zeiss systems?
Both: bottom of illumination arm.
How is slit beam angle controlled in Haagstreit systems?
By rotating the top of the illumination arm; a degree gauge displays the angle.
What is the typical use of the 90D lens?
General central fundus examination.
What are the typical uses for the 78D and 60D lenses?
Disc and macula examination.
What is the typical use of the SuperField lens?
General central fundus examination.
What is the typical use of the SuperPupil XL lens?
General exam through small pupils.
What is the typical use of the Super66 lens?
Disc and macula examination.
