BIO Technique Flashcards
Red free filter on BIO differentiates retinal from choroidal lesions but decreases visibility of
The choroid, and may enhance visibility of the retina
Cobalt blue filter on BIO
Auto fluorescence of OHN drusen
Yellow filter on BIO decreases risk of
Phototoxicity/ less photophobia , less glare
When you turn in BIO make sure you set
Rheostat to about 50%
Set mydriatic pupil setting to maximum dilated
How to do BIO on small pupil (4)
- increase power of lens
- increase WD
- decrease instrument PD
- decrease separation between viewing beams and illumination beam
You maybe adjust mirror height during BIO to
Maintain binocularity and fit the light beam through the slit like aperture if the oblique pupil
If diplopia is encountered during BIO you could adjust (4)
- PD
- headband
- increase WD
- relax accommodation
Adjust IPD ____ until the object is centered in the field of view
Monocularly
20D condensing lens is a good balance between
Mag and FOV
Higher power lenses offer ___ FOV
Greater FOV
Higher power lenses can aid w/examination through ____ pupils
Small pupils
Silver edge in condensing lens points
Away from observer
Yellow condensing lenses are helpful for
Decrease blue light hazard
Reduces pt discomfort
( can miss ONH color)
BIO on seated pt is possible but
Will hinder examination of the periphery
When pt is reclined for BIO adjust their height to
Waist high or slightly lower
Position of pt best for most views
Reclined in primary position
Holding the condensing lens
The extended 3rd finger hold the pts lid and acts as a pivot that allows us to tilt lens
Do not rest your hand on more than a single finger
As the condensing lens is gradually moved away from the pts eye, the pupil becomes
Magnified until it fills the entire area of the lens
If the condensing lens is moved too close to the iris
The peripheral fundus will not be illuminated
If the condensing lens is moved too far from the patients eye
Light from the peripheral retina will not reach the observers eye
How does WD affect magnification
Decrease in WD, increases magnification
WD that’s too short will produce
Difficulties with accommodation, convergence, and possibly diplopia
Excessive tilting of the lens will induce
Cylinder that will distort the fundus image
Entire periphery may be inspected by examining __ meridians using a __ lens. How are you supposed to scan the meridians?
8 meridians
20D lens
Radially from posterior to the equator out to the anterior limit of the fundus
Landmarks from center to periphery?
Equator -> ora serrated -> pars plans
Absorption of UV light ___ with age
Increases
How much UVR reaches retina
Almost no UVR
Cornea absorbs UVR
Lens UVB + UVA
Photothermal AKA
Photocoagulation
Light generates temp increase of 10 degrees above body temp
Photochemical aka
Photic injury
Visible light linitiates non thermal, non mechanical damage, probably by generation of free radicals
Photo mechanical aka
Photodisruption
Mechanically disrupted by acoustic transient and gaseous formation
Photochemical damage is associated with
Longer exposure and extreme wavelength (short wavelength)
A more heavily pigmented iris will ___ retinal irradiance, ___ photic injury
Decrease
Decrease
Greater photochemical damage occurs in ____ state
Dark adapted
Higher levels of macular pigment, usually associated with higher dietary intake of the carotenoids
Lutein and zeaxanthin, believed to be more protective
Factors affecting risk of photochemical damage
Location of retina Macular pigment optical density Iris pigmentation Dark adaptation state Phasing state Preexisting disease
Photochemical damge in aphasia
Higher risk
Possible protective effect of blue blocker IOLs
Physical factors of light that are cause risk
Shorter wavelength of visible light
Higher intensity
Continuous exposure
A thermally enhanced photo toxic reaction at the outer retina and RPE associated with sun gazing
Thermally enhanced photo toxic reaction
Symptoms of maculopathy
Decrease vas Central scotoma Metamorphosia Micropsia Dyschromatopsia
In solar maculophathy acute phase, there’s usually a smal yellowish fovea lesion which usually
Fades after 2 weeks and is replaced by small multifaceted outer retinal hole w a pigment halo
Slit lamp vs BIO retinal irradiance
Slit lamp causes 2-3 times greater retinal irradiance than BIO
Use of a yellow lens during BIO increased safe periods by
Factor of 20 to about an hour
Retinal irradiance vs lens power
Retinal irradiance decreases with increased lens power
There are numerous reports of retinal light injury caused by operating microscopes during cataract and virectomy surgery
True
20D lens provides an ___ FOV
8DD field of view
Lesions that are more peripheral in the fundus are
More anterior in the eye
What’s at the center of fundus drawings
Fovea
For scleral depression the tip is places
On horizontal fold which is the tarsal plate
During scleral depression do not
Lift handle of inventor any more than necessary to accommodate the condensing lens
Slide it laterally and move it more posteriorly
