5. A solid objective with two l denticalends and flat sides the shape of
the ends give the prism a nam such as triangular prism .
.Type ofprism :
1. Reliving prism
2. Prism reflex
4. prism adaptation
5. corrective prism
6. .In order to move the image to where the eye is
looking „ thus restoring fixation and binocular vision:
.Base of the prism is placed over the weak ( or
8. Krimsky test
▪️This test is used to
centralize the corneal
rflaction in the
squinting eye with
compared to the fixing
9. Prism reflex test (krimesky’s corneal reflex test)
1- objective method .
2- performed at near with point
light as fixing target .
3- materials required : prism bar ,
pen light .
4- useful in large squint .
10. 1. Used to investigate BSV and find small angled deviation in infant and
2. Fixation pattern of fixing eye is studied with horizontal BO prism in
front of fellow eye.
3. Same procedure is repeated for next eye too.
4. Commonly used prism is (10▲BO _ 25▲BO)
5. By inducing tropia, fixation preference is studied.
Prism reflex test (induced tropia test)
14. - also known as the corneal light reflex test .
- is quick and simpl way to check ocular alignment.
- this assessment is particularly useful for testing for
- in newborns, young children, patients with poor vision,
patients that are not able to fixate or track well.
- or in any situation where a full motility evaluation is not
Hirscheberg Test (cont) :
15. measurement and the gold standard in
measuring strabismus, i.e. ocular
misalignment, or a deviation of the
Prism cover testis an objective
16. - :Measures manifest component only
Utilises cover - uncover - Used for a
patient who has underlying latent
deviation in addition to a small manifest
deviation ( i.e. microtropia )
Simultaneous prism cover test
18. 1 –Case history
3 –Visual acuity
4 –Cover test
6 –Binocular function
19. :some children with esotropia manifest only aproportion of their full angle
of squint and if they are corrected either whith prisms or surgery the will
increase to this full angle . preoperative prism adaptation helps to
diagnose the maximum angle of deviation and potential for abinocular
result in these children it is most useful in those who ,on testing , can be
shown to demonstrate peripheral fusion at an angle great than their angle
of deviation these patients fusion at an angle rected surgically if they were
not prism and the amount of surgery is there fore correspondingly
increased it is therefore important to know the full angle of squint before
surgical intervention .
Prism adaptation test
20. - correct the refractive errior and treat
amblyopia if present
-the angle of deviation often reduces following
amblyopia treatment resulting in fewer cases
that actually require surgical managment for
-surgery may be for acorrective or functional
Corretion of tropia by prisms
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