Using the indirect ophthalmoscope proficiently is a difficult skill to master, nevertheless is an indispensable one. With adequate practice, you will eventually come to terms with it. Here are a few tips and tricks to help you with it.
Important but often likely to be missed:
- Every day, check if the optics of the indirect ophthalmoscope is working properly and, if wireless- that the battery pack is charged. (Finding out that the optics is not working properly or the indirect ophthalmoscope switching off in the middle of the examination is not only embarrassing but may also undermine the impression that your patient will have about you).
- Have a dedicated switch to turn off the room light nearby your examination station. It is often easier to “do it yourself” than to command to others/assistant for the lights on and off.
- Ask them if they are driving or riding or have an important work immediately after the visit at your clinic. Defer the examination to a later time/date if any of the above exists.
- Firstly, explain the procedure to the patient and keep them at ease as well as get their verbal consent to carry out the procedure. It is also better to explain and test them with “ocular motility” evaluation like tests before the actual examination with a bright light shining in front of their face. Also rule out any eyelid pathology– such as ptosis at this stage.
Dilatation and examination :
- Make sure the patient’s eyes are well dilated so that the peripheral retina can be viewed easily and adequately. You can use 1% tropicamide and 2.5% phenylephrine combination eye drops, if no contraindication exists.
- Rule out any eyelid, anterior segment and vitreous pathology at a slit lamp examination before beginning.
- The most optimal position for the patient is supine or reclined at 45-60 degrees with enough room for you to move around the patient’s head and examine from various angles. You will be viewing the retina directly opposite of where you are looking from.
- To align the oculars and light spot of your indirect headset after you put it on, extend your thumb at an arms’ length and close each eye at a time to make sure you can see properly from both.
- Make sure you don’t keep the brightness too high. It will make the patient uncomfortable as well as initiate the Bell’s reflex causing uprolling of the eyes. You can initially start with a lesser brightness level and increase it as the patient gets acclimatized.
- It will be easy for you to hold the lens properly if you use your thumb and index finger and keep your fifth digit on the patient’s forehead or cheek.
Tip of Mentors:
When teaching your residents / colleagues or friends, in my practice (using the law of optics), you can aid/guide them in visualization of the retina and get an idea if they are aligning well or not.
The rays of light which exists from the condensing lens converges to form a “smallest appreciable” point. This can be checked by moving the 20D lens forward or backwards. This point can be used as an indicator to predict if the alignment or the focus is correct or not. The mentee will usually be able to appreciate the posterior segment of the eye when using this technique and the point as an indicator most of the time.
Additional Tips to the mentee:
To focus the image, go farther away from the lens and not towards it.
a. Starting the examination from the macula can cause discomfort to the patient and decrease their cooperativeness also. You can rather start from the periphery.
b. You can ask the patient to slightly turn their head towards the side you are on, if their nose causes any hurdle.
c. Giving the patient verbal directions to move their gaze a certain direction can sometimes cause confusion. You can instead gently tap their face towards the direction you want them to be looking at.
d. To evaluate the far periphery of the patient’s retina, you can try tilting your own head at 45 degrees towards the left or right.
Scleral indentation must not be missed, especially in patients complaining of flashes and floaters. Although a proper scleral depressor of appropriate shape and size are much more efficient in getting the job done, you can make-shift use a cotton tip applicator also. While examining, ask the patient to look slightly off-axis rather than towards an extreme peripheral gaze. (This is usually done in the end of the examination – and sometimes you can instill proparacaine to numb the eye to make it comfortable to the patient)
If you don’t have an indirect ophthalmoscope with you, you can use a 20D lens and a direct ophthalmoscope to perform a type of monocular indirect ophthalmoscopy known as a direct ophthalmoscopic indirect ophthalmoscopy.
For this, look through the direct ophthalmoscope while keeping the lens between you and the patient’s eyes, as with any indirect ophthalmoscopy. You can use the various filters in the direct ophthalmoscope as per need, as well as use the grid to measure the size of the lesion. However, as there is no binocular view you will lack a stereoscopic view with this.