21. Slit-lamp, red reflex and ophthalmoscopy. Flashcards
what is a slit lamp examination?
a table mounted binocular microscope with an adjustable light source - to view th optically transparent translucent tissues of the eye and anterior portion of the eye - such as the eyelids , conjuctiva , cornea , sclera , cornea , iris and aqueous humour
patient seated and head is stabilised by an adjustable chin rest
the forehead strap where the forehead has to be right against it
start from the front of the eye to the back
angle of illumination varied , along with width , length , intensity of light beam
maginfication variation
what is fluorescein staining of in slit lamp examination
specialized dye that stains the cornea & highlights any irregularities of its epithelial surface
applied to the inner surface of the lower lid - instilling the yellowish dye into tear film
illuminating light of the slitlamp is made blue with a filter
why is there abnormalities in fluorescein staining of slit lamp examination ?
tiny punctate dots of excessive dye absorbtion which indicate excessive dryness of the cornea or UV-damage
Large areas of excessive dye absorption indicate corneal abrasions/ infective ulcers
what is red reflex and what technique is used to see it ?
reddish reflection of the retina produced when light from the fundoscope is directed towards the retinal cells
best observed in dark room , fundoscope arms length and the patient look towards the illuminating light
lens wheel focus the light ray to the plane of the pupil
clear transmission of reddish light indicated healthy eye
what could indicate pathology in fundascope in red reflex ?
lack of a red reflex or the presence of dark spots or asymmetries
Focal opacities which are moving/floating -located in the
vitreous humor , due to small haemorrhages
Focal opacities which are stationary
probably located in the lens
-. cataract or the cornea -scar
Absent red reflex - highly indicative of retinoblastoma
white reflection - leukocoria
two mai types of ophthalmoscopy / fundoscopy which are they ?
direct and indirect
what is the direct method of fundoscopy ?
hand held fundoscope
intensity , colour and spot seize of illumination light can be adjusted
different types of lenses arranged to ensure better view of the multiple structures
with direct method of ophthalmoscopy how is the anterior segment examined ?
using high plus lenses - magnified view of conjuctiva , cornea , iris
what method of fundoscopy examination allows visualisation of the retina ? what structure are visible ?
fundoscope in a dark room , as the patient look towards the illuminating light
the fundoscope needs to be directly placed as close as possible in from of the eye
optic disc
macula
proximal retinal asculature
pharmacologicaly dilating the pupil may enhance the view
in direct fundoscopy what are at the abnormalities which can be seen ?
the disk which is the pale central spot - any dilation - glaucoma
a small pinpoint white reflection - marks the central fovea which is surrounded by more darkly pigmented macula and presents the only AVASCULAR SPOT on retina
vessels studied for aneurysm , hemorrhages and exudates
what is the indirect method for retinal examination ?
binocular indirect opthalmoscope
REQUIRES PUPILLARY DILATION
indirect ophthalmoscope worn on examiners head , allow binocular viewing through a set of lens on fixed power
bright adjustable light source attached to headband worn - directed towards patient eye
additional convex lens held several cm away from patients eye to visualise the image of retina
what are the advantages of indirect method ?
brighter light source - better visualisation through cloudy media
uses both eyes for examination
used to examine the entire retina to the ora errata
these advantages causes indirect ophthalmoscopy to be used pre or intraoperatvely for surgicall repairs in retinal detachment
what is the disadvantage of indirect method ?
inverted images of the funds (back of the eye)
what is a lens wheel in a fundoscope do ?
to focus the light ray in the plane of the pupil
