Autorė: Irina Kezika

1. Refraction
Author: Irina Kezika

2. Case history
 Patient’s personal details
 Visual history
 When patient will use his new glasses: concerning
professional and leisure activities
 Eye health: family history of eye problems, eye infections,
eye surgery, vision trainings undertaken etc.
 Patient’s general health: diabetes, high blood pressure,
allergies, medications taken
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3. Case history
 Reason of the visit
 Nature of the problem: visual fatigue, blurred vision, double
vision
 Location at which problem occurs: in far distance, middistance, close-up, centrally, peripherally
 The circumstances in which the problem occurs: reading,
working at computer screen driving
 The time and frequency of occurrence
 Date and mode of occurrence: sudden or gradual
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4. Objective Refraction
 Auto-Refractometry (the
sphere often over-minused,
because of the stimulation of
accommodation. Cylinder often
over-estimated). The higher
degree of ametropia, the
greater the degree of
imprecision.
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5. Objective Refraction
 Retinoscopy (or skiascopy)
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6. Subjective Refraction
Distance vision
 Determining the sphere
- fogging method (reduce patient’s vision to the
level 0,16)
 Determining the cylinder
-
- Cross cylinder
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7. Subjective Refraction
Distance vision
 After determining the cylinder
- final check of sphere (+/- 0,25 D)
- with an extra +0,25D vision
should be
slightly
reduced; if it is not add the +0,25D
and repeat the checking of sphere
- with an extra -0,25D, vision
should remain the same (or slightly
reduced)
- duochrome test
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8. Binocular Balance
Dissociate the two eyes by:
- alternate occlusion
- vertical prism (3ΔBDR and 3ΔBUL)
- polarizing filters
Note which is patient’s dominant eye, a slight imbalance in favour
of that eye may be conserved. Be careful never to reverse the
natural dominance of one eye relative to the other
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9. Binocular Vision Evaluation
 Evaluation of motor component:
 Head position
 Eye movements
 Tropia and Phoria recognition
Hirschberg
Madox
Von Graefe
Cover test un Prism cover tests
Polarized cross test
 Physional reserves
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10. Head position
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11. Eye Movements
 Ductions : - adduction- nasal
- abcuction- lateral
- elevation- superior
movement of one eye
- depression- inferior
 Versions: - in 8 directions
movement of two eye (conjunctive)
 Vergences: - convergence
- divergence
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movement of two (disjunctive)

12. Tropia and Phoria recognition
 Cover test
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 Prism Cover test

13. Hirschberg
0°
15° 30° 45°
Light source
Precise:
Aprox:
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1°=1,75 ∆
1∆=0,57°
1°=2 ∆
1∆=0,5°

14. Madox
orto
exo
eso
Madox cylinder in fron of OD +
light source
orto
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hipo (od)
hiper (os)
hipo (os)
hiper (od)

15. Von Graefe
+
Prism
Light source
5-6 pd base up in front of OD
os
od
orto
exo
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eso

16. Polarized cross test
Polarized glases + distance polarized test
Helps to evaluate phoria. Depending on the test conditions (type of
dissociation) the phoria will be said to be associated or dissociated.
Whether the test used involves the an element of fusion, perceived in
common by both eyes or not.
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17. Physional reserves
 Prism bar and fixation object
 For divergence (have the patient focus on vertical line)
- base in prism  blur/break/recovery
 For convergence (have the patient focus on vertical line)
- base out prism  blur/break/recovery
 Vertical reserves (have the patient focus on horizontal line)
 Sheard’s criteria fusional reserves opposing the phoria should be
equal to at least twice the phoria for the phoria correctely
compensated
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18. Binocular Vision Evaluation
 Evaluation of sensory component:
 Type of binocular vision:
Bagolini test
Worth test
Schober test
 Stereovision:
Lang test
Titmus test
Polarized bar test
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19. Bagolini test
Binocular
Monocular
+
Monocular alternating
Simultaneous
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Light source

20. Worth test or 4 dot test
Red-green filters + projector test
4 objects = binocular
3 objects = monocular (green filter)
2 objects = monocular (red filter)
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5 objects = simultaneous
Either 3 or 2 (changing) =
alternating

21. Schober test
Red-green filters + projector test
Can be phoria test and type of binocular vision test (but will not
show simultaneous type of binocular vision, because no
physional stimulus)
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22. Lang test
Near distance stereopsis test
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23. Polarized bar test
Polarized glases + distance polarized test
Far distance stereopsis test
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24. Polarized bar test
Binocular and stereovision
direction of gaze
No stereovision in far distance
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25. Titmus test
Polarized glases + polarized test
Near distance stereopsis test
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26. Subjective Refraction. Near Vision
 Minimum addition method
1. Correct distance vision precisely
2. Determine the minimum addition at 40 cm
3. Add +0,75D 0r +1,00D to the minimum addition
4. Check the patient’s visual comfort
- bring the test closer to the patient until the smallest characters are no longer
able to be seen clearly. This should occur at approximately 25 cm from the eyes
(if < 20 cm, the addition is too strong, if > 30 cm the addition is too weak.)
- adjust the value of addition (from 0,25D to 0,50 D) in accordance with required
working or reading distance. If different from 40 cm at which the test was
conducted. Reduce the addition for longer working distance, increase for shorter
working distance.
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27. Verification of Binocular Balance at Near
 Dissociate the patient’s binocular vision
at near
- optoprox at 40 cm, gaze lowered (polarized or
red-green filters)
 Have the subject compare the vision of the right and left eyes
and determine the balance:
- if there is equality of vision between OD and OS the balance is achieved
- if there is difference in vision between two eyes , balance by introducing
+0,25DS on the worse eye or -0,25DS on better eye. Usually no more that
0,50D adjustment is necessary.
Remember about the dominant eye
 Assess acceptance of near vision balance at distance
If the near vision balance differs from the distance balance, in general it is
preferable to favour the near balance and check for that it is acceptable at
distance.
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28. Amsler
Directions:
1. Do remove glasses or contacts normally worn for reading.
2. Distance 13 in/33 cm from the grid in a well-lighted room.
3. Cover one eye say to the patient to focus on the center dot
uncovered eye. Repeat with the other eye.
4. If patient sees wavy, broken or distorted lines, or blurred or missing areas
of vison, you may be displaying symptoms of AMD.
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29. In the Case of Non-Presbiopic Patient
1. Uncorrected ametropia ( hypermetropia, astigmatism)
2. Binocular vision disorder (convergence insufficiency, severe
heterophoria)
3. Accommodative problems:
- excess/spam (low NRA , ok PRA, low AA)
- insufficiency (not corrected myopia, low PRA, low AA)
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30. Prescribing prism
 Minimum value of the prism that restores comfortable fusion
 Prefer trial frame rather than phoropter
 Consider associated phoria tests and dissociated
 Distribute most of the prism value on non dominant eye (aberration)
 Remember decentration rule P=d(cm)xF(D)
 Follow up visits each 0,5 year
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31. Referrences
 Essilor. Ophtalmic and Optics Files. Practical Refraction.
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32. Thank you!
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