Tips for shooting good stereo pairs
Patients can be difficult for all sorts of reasons and shooting stereo pairs on them can be very challenging. The following four reasons are probably the most common:
- Most study patients will have poor vision making fixation difficult, resulting in lots of eye movement.
However nearly all will be able to fixate on something whether it is the external or internal fixator. If using the internal fixator line up the correct field move to view the left member of the pair and remove the pointer just before you take the shot. Repeat for the right member of the pair.
- Patients who are photophobic, moving away from the camera after every shot. This is very common with young children, not so much with the elderly.
Patients with AMD tend not to be photophobic and are well used to being photographed. More common is that they have droopy eyelids or they feel tired and their eyes close naturally. Hold the eyelid or, if you can’t manage it yourself, ask a nurse to help, remembering that if you are using the external fixator, that the fellow eye must also be open in order to fixate. Allow the patient to blink between shots as if the eye dries this will result in hazy images.
- Elderly patients, possibly with a disability, will find it difficult to position themselves at the camera.
These patients may be in a wheelchair and therefore positioning them at the camera can be awkward. Most, with the assistance of a nurse, will be able to get out of the wheelchair and sit at the camera. Always take time to position them (as with any patient) at the camera so that they are comfortable. Be sure not to lower the table too far and crush legs. If necessary use a pillow on the front edge of the chair in order to tilt the legs downwards.
- The patient feels sick due to the FA injection. This will result in difficulty in sticking to the FA protocol.
If for example the patient feels sick at around 1 min., just as you decide to move to the fellow eye, you will miss these shots. Remember that you can only do your best in these circumstances but talk to the patient and try to encourage them back to the camera, explaining that you only need a few more shots and then they can have a 5 min. break etc., etc.
It is important that the photographer constantly communicates with the patient, letting them know what he/she is trying to do. Tell them that the photographs are taken in pairs and that if necessary they can rest back after every second shot.
If the photographer feels that the movement of the patient is a one off, simply reposition the patient and shoot the pair again.
As the photographer’s skills improve he/she will become quicker. Remember however that it’s not the time interval between the shots that produces the stereoscopic effect; it’s the lateral movement between the shots. Therefore it is possible to capture the two images even after the patient has moved away from the camera.
You can use this technique if you encounter a very difficult patient. If you have captured the first image (the left member of the pair) and the patient pulls back, simply reposition the patient, line up centrally on the correct field, move to the right and then capture the right member of the pair.