Clinical refraction

A presentation on applied aspects of clinical refraction.

1. CLINICAL REFRACTION
Dr Saurabh Kushwaha
Resident Ophthalmology

2. SCOPE
Introduction
Objective refraction
Retinoscopy
Autorefractometry
Subjective refraction
Monocular refraction
Binocular refraction
Correction for near vision

3. INTRODUCTION
History
Visual acuity
Ophthalmic examination
Retinoscopy/ Autorefractometry
Monocular Subjective refinement
Binocular balancing
Near vision correction

4. OBJECTIVE REFRACTION
Retinoscopy
Autorefractometry
Photorefraction
Electrophysiological methods

5. RETINOSCOPY
Prerequisite
•Dark room
•Trial set
•Trial frame
•Distance vision chart
•Near vision chart
•Retinoscope

6. TYPES OF RETINOSCOPE
Reflecting (mirror)
•Plane mirror
•Priestley Smith’s mirror

7. Self illuminated
•Spot retinoscope
•Streak retinoscope

8. TYPES OF RETINOSCOPY
Dynamic retinoscopy
Static retinoscopy
•Wet retinoscopy
•Dry retinoscopy

9. PROCEDURE OF RETINOSCOPY
Ask the patient to fixate on target
Patient’s RE examined with the examiner’s
RE with the retinoscope in right hand
Working Distance about 1 m.
Examiner’s both eyes should be open
Examiner not to obstruct the view of target
Examiner observes a red reflex in the
pupillaryarea
Retinoscope is moved in both horizontal or
vertical meridians

10. INFERENCES OF RETINOSCOPY
PROPERTIES OF REFLEX
Movement
With Need more plus
Against Need more minus
Brightness
Dim Far from neutralization
Bright Close to neutralization
Width
Narrow Far from neutralization
Wide Close to neutralization
Speed
Slow Far from neutralization
Fast Close to neutralization

11. NEUTRALISATION OF RED REFLEX
Myopia :Add -ve lenses
Hyperopia: Add +ve lenses

12. CYCLOPLEGICS IN RETINOSCOPY
S
N
o
DrugName AgePeak
Effect
Duratio
n of
action
Time of
retinosco
py
PCT Tonus
allowan
ce
1.Atropine 1%<5
yrs
2-3
days
10-20
days
4
th
DayAfter3
wks
1.0 D
2.Homatropine
2%
5-8
yrs
60-90
min
48-72
hrs
After90
mins
After3
days
0.5D
3.Cyclopentolate
1%
8-20
yrs
80-90
min
6-18 hrsAfter90
mins
After3
days
0.75 D
4.Tropicamide
0.5%, 1%
-20-40
min
4-6 hrs - - -
5.Phenylephrine
5%, 10%
-30-40
min
4-6 hrs - - -

13. PROBLEMS OF RETINOSCOPY
Poor or invisible red reflex
Changing retinoscopy findings
Scissoring shadows
Spherical aberrations
Conflicting shadows
Triangular shadow

14. AUTOREFRACTOMETRY
Optical principles
•The Scheiner’s principle
•The Optometer principle
Types of autorefractometer
•Objective
•Subjective

15. SUBJECTIVEREFRACTION
Monocular refraction
Binocular refraction
Correction for near vision

16. MONOCULAR REFRACTION
Baseline starting point lenses
Vision
Refractive Error
Spherical Astigmatic
6/6 Small Small
6/9 0.50 1.00
6/12 0.75 1.50
6/18 1.00 2.00
6/24 1.50 3.00
6/36 2.00 4.00
6/60 2.00–3.00 High

17. Refining the spherical lenses

18. Refining the cylindrical lenses
•Astigmatic clock dial & fogging

19. Jackson’scrosscylindertechnique
•Tobringcircleofleastconfusiononretina
•Torefineastigmaticaxisandthenpower

20. Finalisation of spherical lenses
•Fogging technique using Snellen’svisual
acuity chart
•Duochrometest
•Pinhole testing

21. BINOCULAR REFRACTION
Fogging & alternate occlusion method
Duochrometest with fogging
Prism dissociated method

22. CORRECTION OF NEAR VISION
Dynamic retinoscopy
Determination of near add

23. THANK YOU