L8 Flashcards
(13 cards)
What are the key components of a modern direct ophthalmoscope?
Sight-hole lenses, diaphragms, multi-element condensing system, light bulb, wheel for changing lens power, aperture selector, and inclined mirror.
How does the ophthalmoscope illuminate the retina for examination?
Light from the source is reflected at 90° by a two-way mirror at 45° in the head, allowing the examiner to view the fundus through the mirror.
What are some common apertures, graticules, and filters in a direct ophthalmoscope?
Wide angle, intermediate, macular, slit, glaucoma graticule, fixation cross, red free, cobalt blue.
How can lens changes be detected with direct ophthalmoscopy?
By using low illumination and oblique observation; opacities appear dark in retroillumination.
What causes the mottled appearance of the fundus background?
The retinal pigment epithelium (RPE).
What is a tegroid fundus?
A fundus where choroidal vessels are visible due to thin RPE.
How is the position and size of fundus details recorded?
Relative to the optic disc, using disc diameters (DD) and direction.
What are some common abnormalities detected with ophthalmoscopy?
Cataract, glaucoma, diabetes, hypertension, age-related macular degeneration.
What are some normal variations in fundus appearance?
Physiological cup, myopic/scleral crescents, pigmented disc margins, cilioretinal vessels, tegroid fundus, choroidal vessels.
What are some difficulties in fundus examination?
Uncooperative patient, high myopia, high astigmatism, opacity, poor ophthalmoscope, bright room, small pupils.
What are the main advantages of direct ophthalmoscopy?
Portable, easy to use, erect image, moderate/high magnification, simple patient setup, useful for detecting lenticular opacities.
What are the main disadvantages of direct ophthalmoscopy?
Monocular (no stereopsis), small field of view, poor representation of colour/elevation, poor image through opacities, scanning fundus is difficult.
What are the advantages of binocular indirect ophthalmoscopy (BIO) over direct?
Wide field of view, stereoscopic view, less affected by media opacities, range of magnification, increased working distance, useful for uncooperative patients.
