Examination Light

What Is An Examination Light?

Also known as a penlight or examination lamp, this handy little tool is pretty much what its name suggests – a small torch roughly the same shape and size as a pen that produces a focused beam of light to help the physician conduct medical examinations in greater detail.

The whole thing is not usually much longer than 15cm, so it fits neatly into the hand. There’s usually a pocket clip, which in some models doubles up as the on-off switch, and it’s battery-powered, allowing for unrestricted movement and use in any setting. What’s really special, though, is the intensity of its illumination, with the light from the LED or halogen bulbs concentrated into a far narrower beam than you’d get from an ordinary lamp or torch to bring out every last detail in the area under investigation.

Using An Examination Light To Test The Pupillary Response

The eyes have long been dubbed “the windows to the soul”, and while examination of that particular organ would take instruments of a far different nature than you’d find in the typical medical bag, the eyes can certainly open a window onto greater understanding of a patient’s health.

Checking pupil size and reactivity is a staple not only of ophthalmologists but also in general care, neurology, the emergency department and ICU. Shining an examination light into the patient’s eyes and observing the pupillary light reflex – how the pupil size changes with variations in incident light – provides an overview of the autonomous nervous system’s function, uncovering disease symptoms and eye-specific health issues.

Pupil-response tests include:

• Assessing each pupil’s size and shape, and checking for anisocoria (disparity in pupil sizes). Physiologic anisocoria (up to 1mm difference) is a benign condition found in 20% of the population. Anything greater than this should be further investigated as it may indicate underlying pathology,  including concussion, glaucoma and brain tumour.
• Swinging light test – this assesses the pupils’ reaction to the exam light as you quickly move it from one eye to the other. Shining a light into one pupil should cause it to constrict (direct response) and also cause simultaneous constriction in the other pupil (consensual response). If one pupil will only constrict via that consensual response and not when light is shone directly into it, this is known as RAPD (relative afferent pupillary response or Marcus Gunn pupil). RAPD is indicative of a range of pathologies, including retinal infection, ischemic optic disease or optic nerve damage.

The exam light also provides good illumination for general inspection of the conjunctiva, eyelids and corneas, which can reveal signs of many conditions – including common skin cancers such as melanoma, squamous cell and basal cell on both eye and lid, diabetic retinopathy (with dilated examination), rheumatoid arthritis (manifesting as scleritis) and early cardiovascular disease (indicated by a white ring around the cornea).

Is A Pupil Gauge A Must-Have On An Examination Light?

A pupil gauge is a series of circles of increasing diameter on the side of the examination light, which can be used as a guide for measuring pupil size. It’s unlikely to be of much use to a qualified doctor or nurse with many years’ experience in making eye assessments, but it can help students and other trainees feel more confident about developing their own skills.

Reusable V Disposable Examination Lights

Reusable examination lights are built for high-frequency use, with a robust case and pocket clip typically made from brass, aluminium or stainless steel to protect them from knocks and breakage. Look for one with at least a 1-year warranty – premium models may be guaranteed for longer. They’re the best choice if you know you’ll be relying on them during the majority of your shifts and also if you’re keen to minimise your impact on the environment by purchasing products with a longer lifespan.

If you like the reassurance of always having a couple of exam lights to hand (so if one wanders, you’re still covered), or if you’re at the start of your medical career and buying your kit on a tight budget, you might find disposable penlights are your best option. They’re lower in price than reusables, which means losing one (or having to scrap one that’s become heavily contaminated) is in in “small potatoes” rather than blow-the-doors-off-your-bank-account territory. Plus, they’re often sold in multi-packs, so you’ll have enough to squirrel away in a multitude of different places for both convenience and peace of mind – a couple in your pocket (one for you and one for that inevitable loan), one in your bag and a couple in your locker. They’re more likely to be made of plastic than metal, but a good one will still come with a 1-year guarantee.

Additional Uses For Your Exam Light

With its narrow, concentrated beam, the exam light is an excellent tool for assessing other small areas of the body, including the mouth, nose and ears, as well as cuts, grazes, burns and wounds – in fact, anywhere that close attention needs to be paid.

It’s also very handy when checking on patients throughout the night shift. Many studies have found that hospital patients experience impaired sleep, which is associated with weakened immunity, cognitive impairment and slower recovery rates. One way to minimise sleep disturbance during night-time ward rounds is to use a penlight as a torch rather than switch on the overhead lights. As well as being shone directly around the room, the exam light can be aimed at the ceiling, bouncing off to produce a soft, even illumination.

Quick Facts About Examination Lights

• Exam lights owe their existence to an Englishman in New York. In 1899, David Misell created the world’s first electric torch by fitting 3 dry cell batteries into a tube that served as a handle, connecting them to a carbon-filament lightbulb with a brass reflector and adding a switch. His invention became known as a “flashlight” because the inefficiencies of both those early batteries and the filament meant it could only be used for short periods – or flashes – before it had to be rested.
• In 2019, while out jogging in Carmel Valley, California, retired public health researcher Dianne Travers-Gustafson ran into a thick cloud of tiny face flies. A month later, with her eyes watering continuously, she investigated with an examination light and a magnifying mirror, and found several roundworms wriggling around in her conjunctiva. These were later identified as cattle eye worms, Thelazia gulosa, whose vector is Musca autumnalis – the face fly. Travers-Gustafson’s case, documented in the journal Clinical Infectious Diseases, is only the second reported case of human T. gulosa infection in the world.