Using ophthalmoscope - refractive error for examiner and patient

[doubledoubleswifty]

Hello,

I was wondering if both the patient and the examiner had a refractive error, is there a way to estimate which lens would one use on the ophthalmoscope?

For example I am short sighted ~-1.5D, if the patient was longsighted for example ~+5D. What lens should I use on the ophthalmoscope?

And also, should I remove my glasses when using the ophthalmoscope?

Thank you!

[apugrad]

Yes, It is simple to apply. Add the two numbers together i.e -1 plus +5 = +4 lens on the ophthalmascope. However, what you tend to find is that you are accommodating and to counter this you need to look through a more minus lens, so don't be surprised if you have a -5 in the ophthalmascope. Doesn't really matter as long as the fundus is clear.
I would recommend no glasses unless you have significant astigmatism, added lenses in the system leads to more abberations and reflections.

My tip would be to start with a +8 lens, which has a focal length of 12.5cm, observe the anterior eye and report this to an examiner, then slowly rack to 0 or minus lens as you get closer to the eye. Thus, you will focus through the crystalline lens (and be able to say if its clear or not) and then through the vitreous and eventually the fundus (I hope!)

There are many different querks to direct ophthalmoscopy, but just do what you feel comfortable.

[doubledoubleswifty]

Thank you very much for your very helpful reply!

I must say when using the ophthalmoscope I have never really considered looking at the anterior eye, lens and vitreous. I kind of jump straight in and look directly at the fundus but your explaination has been superb!