Lab Info Flashcards
the ciliary muscle and iris sphincter are supplied by what nerve fibers from what ganglion?
parasympathetic nerve fibers from ciliary ganglion
the dilator muscle of the iris is supplied by what nerve fibers from what ganglion?
sympathetic nerve fibers from superior cervical ganglion
mydriatics have what affect on accommodative amplitude
decrease because pupil can’t constrict and you lose depth of focus
mydriatics have what affect on distance phoria
little to no change because of pinholes
mydriatics have what affect on near phoria
little to no change because pinholes and ciliary muscle not changed
mydriatics have what affect on NPC
no change or little receding change due to DOF
cycloplegics have what affect on accommodative amplitude
decreased
variation based on iris color
cycloplegics have what affect on distance phoria
no significant change because pinhole and no accommodation needed at distance
cycloplegics have what affect on near phoria
should go more eso- trying to accommodate more
cycloplegics have what affect on NPC
can’t see stimulus clear enough to fuse
how is AC/A ratio calculated
AC/A= (15-d+n) / 2.5
eso is + value
exo is - value
what test evaluates the quality of the tear film
TBUT
how can TBUT change with artificial tears and anesthetics?
stayed the same or increased- so lower TBUT because faster time (because increased evaporation rate)
what is evaluated with the Jones I and II tests?
drainage
tears running onto the cheek (epiphora) may be caused by:
- hypersecretion
- insufficient drainage
where is the blockage if the Jones II test shows dye and saline in nose
blockage in sac/duct
{(this assumption 78% accurate)
where is the blockage if the Jones II test shows only saline in the nose
blockage in canaliculi or puncta (fluorescein didn’t reach sac)
where is the blockage if the Jones II test shows nothing in the nose
complete obstruction of sac/duct
Jones Test I is falsely positive (no dye discovered) in ___% of tests
22%
the Schirmer I test measures the reflex and basic secretion of the ____ layer
aqueous
norms for Schirmer I Test in 20s age group is
40-50 mm wetting
what is considered a normal Schirmer test I values?
10 mm or more- normal and dry eye problem should not be based on aqueous production problems
why is the basic secretion test used?
to isolate if defective secretion seen in Schirmer 1 is from the reflex lacrimal glands, accessory lacrimal glands, or both
reduced tear volume causes what issues that the rose bengal tests for?
reduced tear volume causes a degeneration of corneal and conjunctival epithelium especially in the exposed interpalpebral aperture
the diagnosis of keratoconjunctivitis sicca (aqueous deficient dry eye) is positive when:
a characteristic triangular stippled staining of the temporal and nasal bulbar conjunctiva (base towards limbus) in the interpalpebral area and punctate staining of the inferior 2/3 of the cornea is observed
what does the ophthalmometer/ keratometer measure and compute?
determines the radius of curvature of the cornea, from which the dioptric power is computed
how does the ophthalmomometer/ keratometer neutralize the measuring problem caused by minute eye movements?
the image of the mire is doubled and minified
main assumptions of the ophthalmometer/ keratometer
- spherical surfaces
- regular astigmatism
how do you record findings on keratometry?
minus cylinder form with the axis of the weaker meridian
is the cornea flatter or steeper in periphery?
steeper?
the keratoscopic disc card is based on what imagery
they use the first Purkinje image formed by reflections from a small portion of the central corneal zone
how would you use measurements from a photokeratoscopy image to record cylinder?
-long axis is the (-) cyl axis
4 examples of how the sensitivity of the cornea is changed by local pathological processes
- chemical injuries
- corneal ulcers
- glaucoma
- herpetic keratitis
average corneal diameter
11.5
most important clinical factors in distinguishing different types of glaucoma
- drainage angle
- visual field changes
- optic disc appearance
- intraocular pressure
the water drink test is for what type of glaucoma?
open angle
water drink test resulting in an increase of ___ mmHg IOP is suggestive of open-angle glaucoma suspect
8 mmHg
what conclusions can be made for an abnormal dark room prone provocative test?
8 mmHg increase in pre- to post-testing suggestive of narrow angle glaucoma
mydriasis test results can suggest:
an increase of 8 mmHg in an hour suggested an angle-closure mechanism
the pressure increment when changing from the seated to supine position averaged ___ mmHg
- 9 mmHg in normal eyes
3. 9 mmHg in glaucomatous eyes
how does IOP change with corticosteroid use differ in normal versus open angle glaucoma patients?
5% of general population sustains an elevation in IOP
90% of pts with chronic open angle glaucoma sustained increased IOP
a suggested theory on how the IOP increases in corticosteroid use is
mucopolysaccharides content of the trabecular meshwork might be altered with increased resistance to aqueous outflow
