A Guide to Building Your Own Diagnostic Set

Infographic showing main components in a diagnostic set

iagnostic sets are a key tool for clinicians, allowing nurses, doctors and other medical staff to perform an initial diagnosis of the ears, eyes and throat. While the building blocks of any diagnostic set are the same, there are a plethora of options to choose from when it comes to different features and brands. Below, we briefly explain what a diagnostic set is, then dive into its two main components—ophthalmoscopes and otoscopes—as well as how to use them.

What Is a Diagnostic Set?

A diagnostic set is a set of medical tools used to diagnose patients by examining the ears, eyes and throat. The set may consist of a single powered handle with different attachments that can be switched out to examine different areas, or it may consist of two separate devices, an ophthalmoscope and an otoscope (much more on these below).

Whichever option you choose, the devices follow the same basic design. The base/handle of the device features a strong light source and a magnifying glass, which work together to illuminate and enlarge the ears, eyes or throat so clinicians can more easily exam these small, delicate areas with precision. Pediatric versions of these devices are often scaled down so they’re proportional to little patients.

If you’ve ever had an annual wellness exam, then your doctor has definitely used a diagnostic set to look down your throat or peek into the inside of your ears. A diagnostic set comes in handy during pretty much any routine visit, and it’s also usually the first tool clinicians reach for if a patient is complaining of pain or discomfort in the ears, eyes or throat so they can check for signs of inflammation.

While stock exam rooms and clinic suites do often store diagnostic sets, many nurses, doctors and other clinicians like to purchase their own personal set that is exactly to their specifications. Some even carry two versions if they see both adult and pediatric patients, since the scale of the devices is different. Welch Allyn diagnostic sets are the most well-known name in this category, but other brands do make them as well.

Below, we break down the different parts of the diagnostic set, explaining what to look for when you buy and how to use the devices.


Choosing an Ophthalmoscope
A critical part of any diagnostic set, an ophthalmoscope is used to examine the back of the eyes. There are two main types of ophthalmoscopes–the traditional standard direct attachment (which points straight up from the handle) and the Welch Allyn PanOptic head (which points out perpendicular to the handle). Each of these also comes in several versions that offer different features even within the same type.

Generally speaking, the standard direct ophthalmoscope uses a halogen light to illuminate the cornea for true tissue color and a polarizing filter to virtually illuminate corneal reflection. The apertures and filters can be combined in various pairs to examine different parts of the eye. However, the number of apertures, filters and lenses that come with the standard direct attachment vary depending on how advanced it is. (For example, a base model might have 28 focusing lenses, while a more advanced one might have 68.)

The PanOptic attachments are more expensive, but also a lot more powerful. This design uses a patented new optical design called Axial PointSource Optics which allows the user to more easily enter small pupils. The technology also provides a field of view of the fundus that’s five times larger than ever before achieved with a standard ophthalmoscope in an undilated eye (25° field of view).

PanOptic ophthalmoscopes use LED lights combined with a half-moon or slit aperture to illuminate the eye. The tube of the device allows you to work six inches from the patient’s eyes for improved comfort. More advanced versions also include red-free and cobalt-blue filters, as well as the ability to combine with the iExaminer app to digitally capture, store and share fundus images.

The standard direct ophthalmoscope is usually fine for doctors, nurses and other clinicians just starting out, but those who specialize in ophthalmology practices may want to consider upgrading to a PanOptic attachment.

Infographic showing main components in a diagnostic set
Male doctor using ophthalmoscope to examine a female patient’s eye

Using an Ophthalmoscope
To use an ophthalmoscope, you’ll first need to check that the device is fully charged and functioning properly. Turn on the power switch to make sure the light comes on. Remove the aperture cover (if it has one) and look through the ophthalmoscope to make sure everything is clear.

If the ophthalmoscope is good to go, you’ll need to select the appropriate aperture and filter setting. Obviously, this varies from patient to patient (not to mention how dark or light the examination room is), but here’s a quick overview of the core options:

  • Large, medium or small light source: depending on how well-lit the room is and how well the pupil is dilated
  • Half-light: used to pass light through only part of the pupil
  • Red-free light: improves contrast to better show blood vessels and hemorrhages
  • Blue light: used in conjunction with fluorescein staining to observe abrasions and ulcers in the cornea
  • Slit beam: illuminates contour abnormalities in the cornea, lens and retina
  • Grid: used to estimate distances between retinal abrasions

After selecting your aperture and light settings, you’ll focus the instrument using the (you guessed it) focusing wheel. The zero setting is the baseline. The positive/green numbers are used to focus on things that are close to you and the negative/red numbers are used to focus on things that are further away.

Now it’s time to find and examine the retina. Darken the room and ask the patient to look at the back wall in order to dilate the pupil. Position the scope against your right cheek and eye and then look into the patient’s right eye. If things look blurry, adjust the focusing wheel until they are clear.

Look 15 degrees of the center of the eye to find the red reflex, and then follow it until you find the retina. Once you locate the retina, you can angle the ophthalmoscope around the eye to examine it. If you’re using the PanOptic, simply ask the patient to look in whatever direction you want to examine and you’ll be able to see the retina or macula.


Choosing an Otoscope
The other half of the diagnostic set, an otoscope (sometimes also called an ear speculum) is used to examine the ears and throat. Otoscopes follow the same basic design, and the main difference is that some come with a throat illuminator while others don’t. Mini pocket versions, called otolites, are also available but these aren’t nearly as powerful as full otoscopes.

At a very basic level, otoscopes all look the same, but there are subtle differences among them that can affect the price point. For example, Welch Allyn’s MacroView otoscopes (either with or without the throat illuminator) offer twice the field of view and 30 percent greater magnification than a traditional otoscope. Also, they have the ability to adjust the focus to fine-tune the view, thanks to the use of advanced fiber optics. These features virtually eliminate the need for panning and simplify seeing past wax and locating fluid behind the eardrum.

Other possible features include a focusable eyepiece that lets you perform examinations without your glasses or adjust for the variable ear canal length, a tip grip for secure fastening of ear specula along with an ejection feature for disposal and a detachable head for high-intensity throat illumination or penlight.

Just as with the ophthalmoscopes, you’ll need to consider how much power and fine-tuning you need to get from your otoscope before selecting a model. Ears, nose and throat (ENT) specialists often invest in a more precise device that offers a lot of features, whereas nurses and doctors working in other areas often do fine with a basic otoscope. No matter what type of device you choose, you’ll also need to get a supply of hygienic plastic covers for the speculum to help keep the device sanitary.

Male doctor using an otoscope to examine a young child’s ear
Otoscope and macroview otoscope against a gray background

Using an Otoscope
As with the ophthalmoscope, you’ll want to turn on the device and look through the lens to make sure you have power and that nothing obscures your view. If you’re examining the ears, hold the back of the ear lightly with one hand while maneuvering the otoscope with the other. Bring your eye towards the viewing end of the otoscope and gently insert the device into the ear, carefully moving it around until you can see the ear canal. Make a note of any abnormalities and then repeat the process on the other ear.

If you place your pinky finger against the patient’s cheek while examining the ear, that will brace the otoscope and keep it from accidentally slipping. This is especially important when examining children, as they have a tendency to wiggle suddenly and you don’t want the otoscope to slip and damage the eardrum.

As for examining the ears, have the patient open wide (“say ahhh!”) and inspect the oral cavity using the light of the otoscope. Use a tongue depressor to gently press down on the tongue to expose the tonsils and the pharynx if you need to, and don’t forget to have them lift their tongue so you can examine its underside and also the floor of the mouth, making a note of any abnormalities just like with the ears.


Whether you purchase a single handle plus attachments or two separate devices for your diagnostic set is up to you. The handle plus two attachments gives you more pieces overall to keep track of, but you also only have to remember to charge one device (the handle) as opposed to both the ophthalmoscope and the otoscope.

If you’re purchasing a diagnostic kit with interchangeable attachments, you’ll choose the handle separately from the instruments themselves. While the handle may seem very humble, the instruments are totally useless without the light and power from the base. While all handles do the same basic tasks (providing light and power to the ophthalmoscope and otoscope attachments), there are certain features you should look out for.

You’ll be handling the devices a lot, so it’s important that the base sits comfortably in your handle while still being made of durable material that will stand up to daily use. For example, Welch Allyn makes their diagnostic handles out of chrome-plated brass for durability, and etches the metal with a smooth, non-abrasive knurled finish for a no-slip grip. The head connectors that attach to the instruments are also made from metal for durability. Finally, the handle is also designed to distribute the weight evenly so it sits comfortably in your hand.

The handle also needs to combine the necessary intensity of light with battery life. Welch Allyn handles run on a long-lasting rechargeable nickel-cadmium battery, plus a safety switch to prevent accidental draining of the battery. The handle also features an adjustable rheostat control and a free-floating reserve setting that facilitates optimal intensity and battery life.

Of course, batteries don’t last forever, which is why you’ll want to look for convenient built-in chargers that plug into conventional wall outlets for overnight recharging. Certain models include a battery converter accessory that allows the handle to be powered by C-cell batteries in a pinch, a very helpful feature if you're on call or have forgotten to charge the battery.

As with any expensive product, you should check to see if the brand offers a warranty in case something goes wrong. And of course, you’ll want the handle to be compatible with your attachments, so you should buy them all from the same brand to ensure the proper fit.

Only you can know the right diagnostic set for you, based on your patients, specialty and personal preferences. However, if you need help deciding, we’re happy to provide assistance or you can check out the Welch Allyn diagnostic set builder for some interactive online support.