Manual Refraction

[Deepak]

Friends,

This is my happiest moment joining three O's party,Hi all!

I am studying manual refraction and always get difficulty locating correct axis. Any hints will be very much appreciated.

Good wishes,
Deepak

[Optom]

Hello Deepak,
Get this small book called MONOCULAR SUBJECTIVE REFRACTION by Freeman. You can this from ABDO bookshop.
I hope this will answer your questions.
Regards,
Optom

[Stopper]

If you really want to learn to how to narrow down your axis. Learn to do retinoscopy before you start the refraction. This should give you a good starting point to refine the refraction.

[Deepak]

Optom
Thanks for directing on right book,that is what I needed.

Stopper
I do not learn retinoscopy at the moment,noted your hint.

Harry Jilson

My appreciation and gratitude for your warm welocome mail.

Deepak
Dispening in UK;)

[Optom]

Hello Deepak,

I guess you mean locating axis using trial & error method of subjective refraction. Use astigmatic fan & block chart. It is best way for subjective assessment of astigmatic cases of refraction. You can also do manual refraction with staenopic slit. Staenopic slit is an opaque disc with 1 mm thick slit running across the center. It can be found in your trial lens set or phoropter head.
Do as follows:
1) Take patient’s PD, center trial frame to the measurement and direct patient to Snellen chart.
2) Insert slit in right eye cell of frame and block the left eye.
3) Rotate slit by 180 degrees. If the patient has astigmatism his vision will significantly improve in one particular position than the other. Read off the axis at the position of the first improvement. This represents axis of one of the two principal meridians. Add spheres in this meridian until you achieve the best visual acuity, for example @ 030 degree you bring your patient to 6/6 with –2.00DS. Rotate slit right angle to first meridian position i.e. @ 120 degree and continue adding spheres until you again achieve best visual acuity, let say you get –3.50 @ 120 which brings your patient vision to 6/6.
4) Put down your findings on an optical cross. Weaker power is sphere power, difference of two is amount of cylinder, axis at weaker power.
In this example his subjective refraction is: -2.00DS/-1.50X030.
Repeat the same for left eye.
Refine your results with cross cyl, duochrome test, binocular balancing etc as per instructions given in your books on refraction.
You can check vertex distance too using staenopic slit. Ask patient to close the eye and pass mm rule through slit until it touches lid, read off the distance in mm and deduct 1 mm for lid thickness.
Regards,
Optom

I too recommend you learn to use retinoscopy (streak type), it is an effective tool in determining the presence of refractive errors in adults. Retinoscopy with cycloplegia is the most appropriate method of determining refractive errors in children, given the accommodative status of children. But you will still have to check with subjective refraction and so forth…

[Deepak]

Thank you for making subjetive refraction easy for me.Liked you idea of meauring bvd with slit n mm rule.
How many retonoscopes types are om market.

[Stopper]

There are two types of retinoscopes. Spot and Streak. You want a streak retinoscope. Copeland is a great brand for this. Also Heine and Welch Allyn make good ones as well. We have all three types and all work well.

[Maria]

In what capacity are you learning it? DO, OO, or contacts?

[Deepak]

Thanks,many tahnks Stopper my guru,now tell me the best types for me,spot is cheaper.I got quotation of whooping sterling pounds 700 for a set.
which one should i buy n whu?

Maria darling

i m DO studying delegated refraction;)

[Stopper]

Buy the streak retinoscope. It will be the best at refining astigmatic axis which was your original Question if I remember correctly. My favorite is the copeland but it tends to eat batteries compared to others. Heine would be my second choice. I'm not sure what the conversion to dollars would be but that sounds like alot.

Also FYI, Retinoscopy is VERY helpful when refracting Children. Especially young ones.

Do you refract with a + or - cyl Phoropter?

[Deepak]

I refract suing trail case,never used phoropter

[Stopper]

Really? I'm impressed. That must be time consuming. Invest in a phoropter. It will be more effecient.

[chip anderson]

Stopper: A phoropter/refracter may be more efficent in terms of your valuable "chair time" but the results as far as accuracy do not compare to a good refractionist using a trial frame.

Chip

[Stopper]

Chip,
I never mentioned anything about accuracy. I'm sure that he does an excellent job with his manual refraction. Like I said " I'm impressed". But efficency is important. I imagine that is why most lenses are surfaced, edged and beveled with machines and computers these days instead of manually even though a good optician could do it manually. It would take too much time and wouldn't allow an optician to make enough spectacles to stay in business.

[Optom]

Deepak is still a student, I believe he has plenty of chair time to play with human guinea pigs:D. Anyway,for starter I would recommend trial lens set & trial frame.
Once he qualifies and gets busy doing refractions,phoropter will be right gadget for him.
Regards,
Optom

[Deepak]

I have no problem using refractor head at distance testing,but when it comes to testing for near i feel more comfortable with trail frame,so I dubbed phoropter for trial frame.
Thank you evry one for the all help.

[Deepak]

I acquired used sterak retinoscope make of Keller for US$ 200.Is the price OK?

[Stopper]

Keeler is a good brand also. That sounds like a fair price. But I haven't bought a new one in 12 years.

[sarahr]

Deepak, have you discovered the brilliant interactive cross cyl tutorial on the ABDO website. (Student area)
Sarah:)

[Optom]

American Academy of Optometry(British chapter).I hope you'll find it useful.
Regards,
Optom