1. PRACTICE OF REFRACTION
Dr. C. R. Thirumalachar

2. Practice of Retinoscopy
Importance of art & science of refraction
Mastery over the principles & practice
Nearly 15 million visually impaired
Refractive errors constitutes 10% of blindness second only to cataract
Early detection, precise estimation , optimum correction is essential

3. Importance of Retinoscopy
Restoration of vision
Prevention of strabismus & amblyopia
Children with poor vision wrongly dubbed dyslexic & mentally retarded
Good vision helps in mental, social, emotional and psychological development and scholastic pursuits
Refraction accounts for more than 50% of ophthalmic OPD work

4. Retinoscopy Objective method of estimation of ref status
Can be done with out cycloplegics (dry refraction)-Will be fallacious – latent & facultative : missed
Precise assessment of astigmatism & axes difficult
Difficult in children, uncooperative patients & small pupils(old & DM) opacities in Media
Cycloplegic refraction essential in children, strabismus

5. Retinoscopy… Cycloplegic refraction essential when
Objective refraction does not tally with subjective acceptance, clarity , comfort
Pts’ symptoms out of proportion to abs. fraction of manifest error
Best cycloplegic – short acting, quick acting, effective, adequate duration , good safety profile, good shelf life, cost factor , side effects

6. Homatropine, atropine, Cyclopentolate
Upto 5 yrs atropine ointment t.i.d. 3 days
Upto 15 yrs atropine drops / Cyclopentolate
Upto 45 yrs Homatropine drops

7. Equipment required
Lister’s bulb, retinoscope, trial frame, trial lenses, occluder , pin hole, dark room, VT charts
Ophthalmologist/ refractionist sits at 1 mt
Pts ‘ accommodation relaxed – pupil dilated
Listers bulb placed behind, above & to one side of pts’ head
Retinoscope mirror reflects light to pts’ eye

8. Retinoscopy Procedure
Begins with directing light into pts’ eye and illuminating area of retina
Emergent rays from pts eye forms an image
It is referred to as red fundal glow
By convention referred to patients’ pupillary area
Formed at far point (at infinity) of pts eye in emmetropia, in front of pts’ eye in myopia and behind pts’ eye in hypermetropia

9. Retinoscopy Procedure…
Moving the light across the pts’ retina & observing the movement of the fundal glow- ref status is assessed
With suitable lenses, movement of fundal glow is neutralized & error estimated

10. Retinoscopy Procedure…
If fundal glow moves with the mirror(plane), neutralized with plus lenses
If fundal glow moves against the mirror – neutralized with minus lenses
Point of neutralization – no movement of fundal glow will be seen, cross checked with concave mirror
Ultimately pt of neutralization is to achieve 1.0D myopia using suitable lenses

11. Retinoscopy Procedure…
Two meridians (vertical & hori) checked to take care of astigmatism
Both eyes checked to take care of anisometropia
Concentrate on pupillary zone(corneal centre), avoid extreme periphery

12. Calculations Distance (1 mt) factor- 1.0D
Cycloplegic D, to be deduced 1.5D
Eg.
-2.0D
To be deducted : 1.5D
-2.0D
-3.5D
Ref error: -3.5D sph
-3.5D

13. Cycloplegic atropine 1.0D
Distance 1 mt D
Cycloplegic atropine 1.0D
To be deducted D
+6.0D
+6.0D
+4.0D
Ref error +4.0D
+4.0D

14. Eg3. Distance 1mt 1.0D Cycloplegic homatropine 0.5D
To be deducted D
Eg3.
+2.5D
+3.5D
+1.0D
Ref. error +1.0D sph, +1.0D cyl at 900
+2.0D

15. Cycloplegic homatropine 0.5D
Distance 1 mt D
Cycloplegic homatropine 0.5D
To be deducted D
-2.00D, 450
-3.5D, 1350
Error D sph, -1.5D cyl axis 450
-3.5D, 450
-5.0D, 1350

16. After calculations- transcribe into spectacle format
If pt is over 40 yrs ,near vision addition
at 40 yrs- +1.0D , add 0.5D for every 5 yrs upto 60 yrs
Instead of Lister’s bulb & mirror,self illuminated streak retinoscope can be used
With advent of autorefractometer craze for computer testing, art of retinoscopy is dying
With skill, patience & perseverance it is the best method for estimation of ref errors.

17. Thank you.