1. Objective, Subjective and
Objective, Subjective and
Cyclopegic refraction
Cyclopegic refraction
Gauri S Shrestha, M.Optom, FIACLE
Lecturer and Optometrist

2. Objective refraction
Objective refraction
• Examiner determines the refractive state of the eye on
the basis of the Optical Principles of refraction.
• Purpose: To obtain an objective measurement of the
patient’s refractive state.
• Example
– Keratometry
– Retinoscopy
– Optometers
– Auto refractometer
Gauri S Shrestha, M.Optom,
FIACLE

3. Retinoscopy
Retinoscopy
• Static retinoscopy
– To determine refractive state by patient fixating at distance
so that accommodation is at rest
• Dynamic retinoscopy
– To determine refractive state by patient fixating at near,
accommodation is active.
• Principle:
– Estimate the patients refractive state by bringing patient’s
far point at the entrance pupil of examiner with the help of
appropriate lens.
– The state of refraction at this particular point is called as
neutralization.
neutralization
Gauri S Shrestha, M.Optom,
FIACLE

4. Gauri S Shrestha, M.Optom,
FIACLE

5. Gauri S Shrestha, M.Optom,
FIACLE

6. Procedure
Procedure
• Working distance
• Fixation target
• Patient instructions
• Starting point
• Locating principal meridian
• Procedure for spherical ametropia
• Procedure for astigmatism
Gauri S Shrestha, M.Optom,
FIACLE

7. Principle of subjective refraction
Principle of subjective refraction
• Subjective determination of the combination
of sphere and cylindrical lenses that
artificially places the far point of Each Eye of
patient at infinity
• This is the combination of lenses that provides
best VA with accommodation relaxed
Gauri S Shrestha, M.Optom,
FIACLE

8. Purpose
Purpose
• To find the strongest plus lens or the weakest
minus lens which allows the patient to obtain
the best possible visual acuity
Gauri S Shrestha, M.Optom,
FIACLE

9. When to start subjective refraction?
When to start subjective refraction?
• After objective retinoscopy/Auto refraction
• Accurate refining when objective retinoscopy
is inaccurate
– Media opacities, keratoconus, oblique and
irregular astigmatism
• Post mydriatic cycloplegic refraction
• When retinoscope or auto-refractor is absent
Gauri S Shrestha, M.Optom,
FIACLE

10. Subjective refraction techniques
Subjective refraction techniques
• Fogging
• Stenopaic slit
• Jackson’s cross-
cylinder
Gauri S Shrestha, M.Optom,
FIACLE

11. Subjective refraction techniques
Subjective refraction techniques
• Astigmatic fan/
Clock dial/ Sunburst
dial
• Phoropter
Gauri S Shrestha, M.Optom,
FIACLE

12. The sequence of the subjective
The sequence of the subjective
refraction
refraction
• Monocular sphere check
– The Step-Down Technique (Visual acuity method) for
monocular sphere check
– The Red-Green Technique for monocular sphere check
Gauri S Shrestha, M.Optom,
FIACLE

13. The sequence of the subjective
The sequence of the subjective
refraction
refraction
• Astigmatism power and axis
– Jackson Cross Cylinder
– power→axis→power
– If the power of cylinder is
1.00 diopter or more
• Axis check
• Power check
• Note: Add constant spherical equivalent
Gauri S Shrestha, M.Optom,
FIACLE

14. The sequence of the subjective
The sequence of the subjective
refraction
refraction
Fan chart Clock Dial
Gauri S Shrestha, M.Optom,
FIACLE

15. The sequence of the subjective
The sequence of the subjective
refraction
refraction
• Monocular sphere endpoint
– The Step-Down Technique for monocular sphere
check
– The Red-Green Technique for monocular sphere
check
– Note: Perform monocular visual acuity test
Gauri S Shrestha, M.Optom,
FIACLE

16. Binocular Balancing
Binocular Balancing
• Purpose:
– Equalize accommodation between the 2 eyes
• Method
– Prism dissociation technique
– Prism dissociation bichrome balance
– Alternate occlusion technique
Final Fused Binocular Shrestha, M.Optom, Determination
Gauri S
Final Fused Binocular Sphere Power Determination
Sphere Power
FIACLE

17. Difficulties with Subjective
Difficulties with Subjective
Refractive Testing
Refractive Testing
• Intelligence
• Cooperation
• Past experience
• Poor JND ability
• Language barrier
Gauri S Shrestha, M.Optom,
FIACLE

18. Principle of cycloplegic refraction
Principle of cycloplegic refraction
• Determination of total
refractive error during Total Hyperopia
temporary paralysis of
cilliary muscles as an Latent Manifest
instillation of hyperopia hyperopia
cycloplegic drugs which
otherwise doesn’t
manifest on subjective
non-cycloplegic facultative Absolute
hyperopia hyperopia
refraction
Gauri S Shrestha, M.Optom,
FIACLE

19. Indication for cycloplegic refraction
Indication for cycloplegic refraction
• Accommodative esotropia
• All children younger than 3 yrs
• Suspected latent hyperopia
• Suspected pseudomyopia
• Uncooperative/noncommunicative patients
• Variable and inconsistent end point of
refraction
Gauri S Shrestha, M.Optom,
FIACLE

20. Indication for cycloplegic refraction
Indication for cycloplegic refraction
• Visual acuity not corrected to a predicted level
• Strabismic children
• Amblyopic children
• Suspected malingering and hysterical patients
Gauri S Shrestha, M.Optom,
FIACLE

21. Selection and use of specific
Selection and use of specific
cycloplegic agents
cycloplegic agents
• Variable degree of pupil dilatation and cycloplegia
• Instill cycloplegic alone or with mydriatrics
Agent [C%] Dosage Max Duration Residual
cyclople of effect accom
Atropine 1, 2 1D TID 3-6 hrs 10-18 Ngble
sulfate 3 days days
Sco-mine 0.25% 1D TID 60 mins 5-7 days ngble
HBR
Cyclo- 0.5, 1, 2 1D TID 30-45 24 hrs minimal
late HCL mins
Tro-mide 0.5, 1 1D TID 20-30 4-8 hrs moderate
HCL mins
Gauri S Shrestha, M.Optom,
FIACLE

22. Cyclopentolate HCl is the drug of
Cyclopentolate HCl is the drug of
choice in most of the time
choice in most of the time
• Use 1% [C] in children and adult,
• Use 0.5% [C] in infants in combination with 2.5%
phenylephrine
Age (Yrs) Amount deduced
0-6 1.00 DS
10 0.75 DS
15 0.50 DS
20 0.25 DS
30 0-0.25 DS
40 0 DS
Gauri S Shrestha, M.Optom,
FIACLE

23. What does our practice say?
What does our practice say?
• Advise atropine cycloplegic refraction invariably in
the children younger than 2 years
• Advise atropine cycloplegic refraction in esotropic
children (accommodative type) up to 4 years
• After 4 years, advise cyclopentolate cycloplegic
refraction up 25-30 years
• Above 30 years, check amplitude and lag of
accommodation, then advise cycloplegic refraction
Gauri S Shrestha, M.Optom,
FIACLE

24. Spectacle prescribing
Spectacle prescribing
• Prescribing spectacle from cycloplegic finding
is an art rather precise science
• How to prescribe spectacle?
– Concept of emmetropization is necessary
– Esotropic children younger than 4 years, full
refractive correction is prescribed
– With older children, amount of plus can be
reduced till fusion is maintained
Gauri S Shrestha, M.Optom,
FIACLE

25. Gauri S Shrestha, M.Optom,
FIACLE