PC - Direct and Monocular Indirect Ophthalmoscopy - Week 1 Flashcards
What is the image of the fundus in direct vs MIO?
Direct - virtual
MIO - real
Which has the greater field of view, direct or MIO?
MIO
Which has the greater magnification, direct or MIO?
Direct
What is the visual limitation of direct vs MIO?
Direct - equator
MIO - beyond the equator
What is the purpose of various sized apertures?
Selected according to pupil sizes
What is the purpose of the fixation target aperture?
Measures eccentric fixation.
What is the purpose of the slit beam aperture?
Highlights contours and an indicator for depth.
What is the red-free filter absorbed by, and and what can it differentiate? What does it localise, and allow visualisation of?
Absorbed b the RPE and haemoglobin
Allows differentiation of pigment/naevus from blood
Localises pigmentary lesions
Allows visualisation of the nerve fibre layer
What are 3 possibilities if you are unable to focus the fundus image?
Uncorrected high refractive error
Uncorrected astigmatism >1.50D
Media opacities
Name 4 potential problems during ophthalmoscopy, and how to address them.
Insufficient field of view -move closer to the patient Unable to visualise the fundus -check alignment -dilate Unable to visualise macula -direct patient to look at top edge of the light -change aperture/intensity Excessive reflections -check alignment -direct patient fixation
Describe the recording when conducting ophthalmoscopy.
R, L or BE Dilated (drug and %) or undilated Vitreous clear? Media clear? C:D ratio, lamina cribrosa (visible, shape, orientation of pores), SVP, disc/cup margin distinct, peripapillary area (pigment, scleral crescent?) NRR colour, ISNT rule? AV ratio, calibre RNFL - B/D/B observed Macula (reflex?, NAD?, pigmentary changes) Mid or periphery NAD?
