I have taught a lot of Medical Students and PA students over the years and dread the requirement that they purchase a direct ophthalmoscope for their studies--it is expensive and not very handy instrument that doesnt lead to many "Dr House" style moments in their lives.  The otoscope is another matter, but for an eye exam a couple things become obvious very quickly--you cannot see much of anything through a undilated pupil and when you dilate what you see is of little importance.  But the requirement for physical examination must be honored.  (The new scopes from welch-allen with the bellows do give great views by the way...but the price...!) So I have devised a cheap alternative that gives great video views with your old iphone.  Cheap meaning about 10 bucks.  It wont work through undilated pupils just like the real thing but works great with a little Tropicamide and Phenylephrine drops just like the real thing.  The trick with using the iphone is to get the LED, normally a few millimeters lateral to the lens, to align with the lens through a fiberoptic  light guide. This allows the light to become coaxial with the view through the pupil.  It also works well as an indirect ophthalmoscope too.

Step 1: Modding the Cheap Case

Find yourself a cheap hard plastic snap in single piece case on the internet--it should be a couple mm thick. I got mine for a couple of bucks.  The hard plastic seems to enable the use of epoxy to stick to them which is nice. To make it easy to slide in and slide off of your phone you should slice off the bottom half leaving the top intact with the oblong Lens/LED window intact.  You can do this with a bench band saw or any other method you choose.  The opening over the LED has to accommodate a neoprene washer that will sit just centered over the LED but not obscure the lens opening.  You may have to slightly enlarge the case window opening to accommodate it loosely and allow perfect alignment  with the LED.  Place your Iphone in the truncated case and inspect that the washer will center well in the opening.  Do not worry if it is loose as you will be gluing this in place. If a portion of the washer extends over the lens area truncate it off with a sander. I got these from Loews they are called "sealing washers #8" and have an aluminum washer with a bonded neoprene core which works well to seal the light and align the glass fibers. Place a piece of clear plastic tape over your iphone lens  area and replace back into case--this will allow you to glue the neoprene washer in place in perfect alignment while not getting excess glue on your lens.  Center the washer over the LED and epoxy it  to hold it in position.  
cool idea.
Very interesting design.

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