What is a Welch Allyn Ophthalmoscope and How to Use One

In order to carry out accurate and useful physical examinations, doctors need access to high quality tools and diagnostic equipment. Welch Allyn has been producing precise, reliable medical products for over 100 years.

Founded in 1915, the manufacturer has grown to be one of the most trusted in the ophthalmology industry. Today, it supplies its high-quality tools, parts, and accessories to healthcare professionals and research centres around the world. Covering everything from traditional stethoscopes to iPhone-enabled ophthalmoscopes like this PanOptic+ enabled direct ophthalmoscope, Welch Allyn has a plethora of excellent options.

Welch Allyn was founded when Dr. Francis Welch and William Noah Allyn developed the world's first handheld, direct illuminating ophthalmoscope. The tool has been a big part of the company’s identity since the beginning and continues to be one of its most recognisable products. It's also among its biggest sellers, with hospitals and healthcare facilities around the world placing their trust in the Welch Allyn name. 

To help you choose the correct ophthalmoscope for your needs, we take a closer look at the Welch Allyn ophthalmoscope range, how you use it, and what value it can add to your medical practice.

What is a Welch Allyn Ophthalmoscope?

A Welch Allyn ophthalmoscope is an ophthalmoscope produced by specialist medical manufacturer Welch Allyn. It’s one of the brand’s signature products and is sold in countries around the world—either as a standalone tool or part of a complete diagnostic set that may also include an otoscope and aneroid sphygmomanometer. 

An ophthalmoscope is an instrument used to examine the retina. If you’ve ever been for an eye test or visited an ophthalmologist, there’s a good chance they would have taken a look at your retina with an ophthalmoscope. There are two main types of ophthalmoscope: direct and indirect. Direct ophthalmoscopes are used to examine the centre of the retina whereas indirect ophthalmoscopes check the entire retina.

Welch Allyn ophthalmoscopes use either halogen illuminators or SureColor LED technology. This ensures excellent illumination and allows medical professionals to see all elements of the retina.

Welch Allyn ophthalmoscopes come in a range of different sizes and designs. The Welch Allyn pocketscope LED ophthalmoscope is light, compact and easy to transport. The Welch Allyn 3.5 V ophthalmoscope is an advanced instrument with a range of specialist features, while the Welch Allyn Pocket Junior ophthalmoscope is the brand’s most basic model.

Other features include: 

• Rechargeable lithium-ion power handles for increased running time when compared to standard devices
• A range of diopter configurations
• Digital connectivity through the Welch Allyn iExaminer platform
• Advanced coaxial ophthalmoscopes designed to enable easy entry to the eye for increased field of view, true tissue colour, and reduced glare.

How Do Ophthalmoscopes Work?

Ophthalmoscopes work by illuminating either a dilated or undilated eye with an LED or halogen light. This allows the medical professional to see the various elements that make up the back of the eye and check for a number of injuries and conditions. The part of the eye that ophthalmoscopes focus on is called the fundus. It’s made up of the retina, the optic disc and a collection of blood vessels.

Ophthalmologists will check the fundus when screening for diseases and conditions that affect the eye. It’s also often included in standard eye examinations. An ophthalmoscope can be used to check for:

• Damage to the optic nerve
• Retinal detachment or tear
• Glaucoma
• Macular degenerations
• Melanoma
• Diabetic retinopathy
• Hypertension
• Infection
• Cataracts

More advanced ophthalmoscopes offer doctors the ability to alter the aperture, lens and aperture/filter combinations to gain a larger view of the fundus. This can help specialists to make a more accurate diagnosis.

Instrument Parts

Ophthalmoscopes may look straightforward, but these instruments are very complex, with several important parts that make them work.

1. Brow Rest: The brow rest is at the top of the instrument. It assists with proper placement by sitting against the brow of the user, reducing movement and making it easier to see through the ophthalmoscope. 
2. Lens Wheel: This adjustment tool allows the instrument to be focused. The number of lenses varies based on the type of ophthalmoscope you’re using, but the more lenses there are, the more focus options you’ll have.
3. Viewing Port: This is the most important part of an ophthalmoscope – it’s the part you look through.
4. Lens Viewing Window: The viewing window shows the user which lens is currently in use.
5. Diopter Adjustment: This wheel helps with focus and helps adjust the strength of the lens.
6. Head: The head of the ophthalmoscope is the name for the entire top portion, which is usually interchangeable.
7. On/Off Switch: This button turns the device on or off and, in some models, controls the light.
8. Batter Handle: The handle of the ophthalmoscope is used to hold the instrument, but it also contains the battery.
9. Aperture Selection Wheel: This is an additional wheel on the device that controls aperture settings.

Aperture Settings

Aperture refers to a small opening that can control how much light is able to move through a lens. The aperture settings on an ophthalmoscope change the size of that opening, allowing more or less light through.

Each aperture setting allows a different view:

• Small aperture is used to see the fundus while the pupil is undilated. This setting is used in a room with dim lighting. When the small aperture is used, the user has better visibility and depth perception. Issues like subtle microaneurysms, intraretinal microvascular abnormalities (IRMA), or areas of capillary nonperfusion are easier to see using a small aperture.
• Large aperture is used for dilated pupils, typically after mydriatic eyedrops have been given. The large aperture is more likely to be used during standard eye examinations. With this setting, the user gets plenty of light with which to look at the eyeball and its structures, providing a broad view. It is generally used when the room is dimly lit.
• Micro spot aperture is used when the pupil is undilated and constricted and when the room is well-lit. Micro spot aperture is perfect for when the light from the small aperture isn’t quite narrow and focused enough. This setting is used specifically for procedures and imaging procedures where there is a need for extreme precision. It offers a high resolution that is beneficial for retinal microsurgery, laser photocoagulation, and advanced imaging modalities like optical coherence tomography (OCT).

Other aperture settings may be included with your ophthalmoscope depending on the model, including slit aperture, cobalt blue filters, and red-free filters.

Dioptre Settings

The dioptre settings on an ophthalmoscope are the device’s way of adjusting which lens is being used. The higher the number, the more convex the lens is. The lower the number, the more concave the lens. This is controlled with a focusing wheel.

The patient’s focal point will determine the dioptre setting you should choose. Different conditions of the eyeball cause variations in the focal point, so your examination will be customized for each patient.

For example, if your patient has hypermetropia, you will need to use a more convex lens for the examination. On the other hand, patients with myopia should be checked using a concave lens.

Red Reflex

The red reflex refers to the reddish-orange reflection of light from the back of the eye that can be seen during an ophthalmoscopy. Checking the red reflex is important as abnormalities in the reflex can point to a more serious issue.

When using an ophthalmoscope for red reflex, it’s important the lights in the room are turned down low. Doctors should use a direct ophthalmoscope, and the lens power should be set to ‘0’.

The doctor should sit around 50cm from the patient and place the ophthalmoscope close to the eye. The patient should then be asked to look straight into the ophthalmoscope.

When the doctor looks through the ophthalmoscope into the eye, they should see the bright red reflex. The colour and brightness of the red reflex should be identical in both eyes. If it isn’t, this may indicate a problem, and further tests should be carried out.

How to Use a Standard Ophthalmoscope from Welch Allyn

Ophthalmoscopes should always be used by trained professionals. While the instruments are non-invasive, incorrect use can still potentially cause damage to the eye.

When using an ophthalmoscope, it’s essential the patient is seated and still and the correct working distance maintained. Exam lights in the room need to be turned down low, or switched off completely, to optimise the view of the fundus.

Welch Allyn ophthalmoscopes are very intuitive to use. Adjustments can be made to the lens, lighting and filter simply by moving switches and dials on the ophthalmoscope head. Most of these adjustments can be made without removing the ophthalmoscope from the eye, allowing doctors to fine tune their examination quickly and easily.

Filters can be applied to the ophthalmoscope to check different parts of the eye. Red filters are used to look closely at the blood vessels and a red-free filter or cobalt blue filter can be used to check for corneal abrasions or ulcers with fluorescein dye. Slit apertures allow doctors to look at contour abnormalities of the cornea, lens or retina and grids can be used to approximate the relative distance between any retinal lesions found during the examination.

Let’s look at a step-by-step guide for using the direct ophthalmoscope during an eye exam. We recommend this for medical students to supplement your favorite OSCE guide like Geeky Medics!

1. First, make sure the patient is seated, and the ophthalmoscope can be comfortably held at eye level.
2. Adjust the aperture settings on the instrument. Inform the patient that you will be using a bright light to look at their eye.
3. Ask the patient to look straight ahead at the wall and focus their vision.
4. When you’re examining the patient’s right eye, you should use your right hand to hold the ophthalmoscope and look through it with your right eye. To view their left eye, use your left hand to hold the instrument and look with your left eye.
5. Use the hand that is not holding the device to hold the patient’s head still. It’s easiest to put your thumb on their eyebrow to help reduce movement.
6. For placement, make sure to keep the ophthalmoscope approximately 15 centimetres from the patient’s eyeball. You’ll also want to hold it slightly to the right of their head.
7. Now, look for the red reflex. Gradually get closer to the patient until the optic nerve comes into view. 
8. Take the necessary measurements, such as the cup-to-disc ratio.
9. Slowly, move in every direction to examine the vasculature.
10. Back up again so that you can locate the macula and fovea.

Understanding the difference between direct ophthalmoscopy and indirect ophthalmoscopy is important during your exam. Direct ophthalmoscopy is used for stereoscopic vision. You’ll get an upright image with roughly 15 times magnification.

Indirect ophthalmoscopy will give a wider view, and it’s done by mounting the ophthalmoscope to the examiner’s head, who will then put about an arm’s length distance between themselves and the patient.

What is the Difference Between Retinoscope and Ophthalmoscope?

A retinoscope is an instrument used to carry out retinoscopies. A retinoscopy is an exam that’s used to determine the refractive error of the eye. This allows medical professionals to diagnose patients that are farsighted, nearsighted or have astigmatism by examining the field of view. 

During the retinoscopy, light needs to be moved quickly from side to side. From the speed and direction that light moves across the eye, opticians and ophthalmologists can estimate the level of refractive error. Ophthalmoscopes are unable to provide this type of fast moving illumination. The existing Welch Allyn catalogue also includes a range of retinoscopes. These are often sold in conjunction with ophthalmoscopes.

What is The Meaning of Fundoscopy?

A fundoscopy is an exam that looks in detail at the fundus of the eye. It’s also known as a fundoscopic exam. An ophthalmoscope is generally used to carry out fundoscopies as they provide doctors with excellent visuals and a choice of useful tools and filters.

Investing in a high quality Welch Allyn ophthalmoscope is an excellent way for ophthalmologists and other medical professionals to provide their patients with high quality care. Find out more, and learn about the Welch Allyn ophthalmoscopes we offer, by exploring the Medshop store today.

Additionally, stay tuned to the Medshop blog for more information on healthcare equipment and supplies. 

 

Author: Steven John Cumper, B.App.SC. (Osteo.), M.Ost., is a businessman with a strong foundation in biomedical science and osteopathic medicine, who founded and led Medshop to international success, culminating in its acquisition by the Bunzl Group in September 2021, where he continues to serve as Managing Director (Medshop Group).