Ophthalmic microscopes

Applications of an ophthalmic microscope

In anterior segment surgery, the microscope is used for cataract surgery, corneal and glaucoma procedures, microsuturing and the treatment of selected injuries to the eyeball, among other applications. Depending on the procedure, the surgeon observes the edges of the lens capsule, corneal layers, a thin graft, the position of fine sutures and instruments and, in selected glaucoma procedures, structures visible using intraoperative gonioscopy. Contrast, depth perception and a stable viewing axis matter alongside maximum magnification.

In posterior segment surgery, the microscope provides a viewing platform for vitreoretinal procedures, including vitrectomy. It enables assessment of the position of instruments relative to the retina, small vessels, membranes and the boundaries of structures within the available field of view. A configuration intended for these procedures may be supplemented with wide-angle viewing systems or contact lenses for fundus viewing used with intraocular illumination. These solutions extend the area of the posterior segment that can be observed and allow the optical path to be adapted to the procedure.

In each of these areas, the microscope provides magnification and illumination of the surgical field, but requirements for the image, viewing method and control may differ. Individual models and configurations do not offer the same range of functions. The device should therefore be selected for the procedures actually performed, taking into account the microscope head parameters, suspension system and equipment of the individual unit.

What matters when choosing an ophthalmic microscope

Illumination and red reflex

The red reflex is particularly important during cataract surgery and phacoemulsification because it facilitates observation of the lens structures and posterior lens capsule. Its quality depends not only on light intensity but also on how illumination is directed and how the optical system is aligned. Comparing light source power ratings alone is therefore insufficient to assess actual viewing conditions.

Different models use different solutions. Leica M844 uses OttoFlex II, Leica M822 uses coaxial OttoFlex, ZEISS OPMI Lumera T uses Stereo Coaxial Illumination, and Haag-Streit Hi-R 900 NEO uses the adjustable C.RED 900 module, which can be switched off during corneal surgery. These systems help produce the red reflex but differ in their construction and operation. When choosing a particular microscope, it is therefore worth considering the type of light source, the way illumination is adjusted, the design of the illumination path and the equipment in that configuration.

Optics, magnification and focusing

When assessing the optics of an ophthalmic microscope, maximum magnification alone is not decisive. Image resolution and contrast, sharpness across the field of view, stereoscopic vision and the usable magnification range are more important. Low magnification makes orientation and instrument insertion easier, while higher magnification allows details to be observed. As magnification increases, the field of view, depth of field and image brightness decrease, so these parameters should be considered together.

Smooth magnification adjustment, precise focusing and a working distance suited to the procedure and workstation arrangement also matter. The viewing conditions depend on the configuration of the entire optical path, including the objective, zoom system, eyepieces and binocular tubes. Models may differ in their magnification range, field of view and working distance, as well as in the available objective, eyepiece and binocular tube options.

Suspension system and image stability

The suspension system comprises the stand, arms, joints, balancing mechanism, brakes and mechanisms for positioning the microscope head. In ophthalmology, the stability of this system is particularly important because, at high magnification, even a small movement can shift the viewing field or cause loss of focus or the red reflex. The suspension system should dampen vibrations and hold the head in the selected position.

Correct balancing and smooth movement of the head are equally important. The suspension system should suit the complete microscope configuration, including the assistant view, camera and equipment for viewing the posterior segment of the eye. Additional components affect the load and weight distribution, so adequate load capacity, effective brakes and the ability to position the head freely above the surgical field matter when selecting the suspension system.

XY system and positioning

The XY system enables precise movement of the microscope’s optical axis in two directions without repositioning the entire suspension system. In ophthalmology, this is particularly useful when working at high magnification, when even a slight movement of the eye can cause loss of pupil centration or the red reflex.

Operating the XY system via the foot control allows the surgeon to make precise corrections to the position of the optical axis without removing their hands from the surgical field. Smooth, precise movement and the available positioning range are important.

Assistant view

An ophthalmic microscope in its basic configuration is most often offered without an optical assistant view. Depending on the model, it can be fitted with a module attached via a beam splitter or supplied in a higher configuration with an integrated assistant view. For an assistant actively participating in surgery, the integrated solution is more advantageous because it provides better light distribution and greater scope for individual image adjustment.

Depending on its design, the integrated assistant view may allow independent adjustment of focus and magnification and rapid transfer of the viewing module from the left to the right side. In an add-on solution, the beam splitter directs part of the light to the assistant module, reducing the amount remaining in the main optical system and affecting its distribution. This difference matters to both the surgeon and the assistant.

Illumination is one of the key elements in ophthalmology because procedures should be performed at the lowest possible light intensity that allows adequate observation of the surgical field. This limits the patient’s eye exposure to light. For this reason, the way the assistant view is provided should be considered together with the design of the microscope’s optical and illumination systems.

Control and working ergonomics

The controls of an ophthalmic microscope should allow its main functions to be operated without removing the hands from the surgical field. Using the foot control, the surgeon can adjust magnification and focus, operate the XY system and, depending on the model and configuration, control other assigned functions. Button layout and programming options vary between models, so the ability to adapt the controls to the surgeon’s working method matters.

Ergonomics also depend on the binocular tube position, working distance, range of movement of the suspension system and arrangement of equipment around the operating table. An appropriate workstation configuration allows a natural posture during the procedure and free positioning of the microscope without collisions with the assistant viewing module, camera or equipment for viewing the posterior segment of the eye.

Selected ophthalmic microscope models

Ophthalmic microscope models differ in the design of their optical and illumination systems, the way the assistant view is provided and the available suspension system configurations. Devices designed for ophthalmic applications include:

• Leica M844 — uses the QuadZoom optical system and OttoFlex II illumination and is intended for anterior and posterior segment surgery;
• Leica M822 — combines main illumination with the coaxial OttoFlex system and can be configured for anterior and posterior segment procedures;
• Leica M620 — a model for ophthalmic applications, including retinal, corneal and cataract procedures;
• ZEISS OPMI Lumera T — uses Stereo Coaxial Illumination and is intended for anterior and posterior segment procedures;
• Haag-Streit Hi-R 900 NEO — uses the adjustable C.RED 900 red reflex module, and the 900A variant includes an assistant view.

Further information about devices from individual brands can be found on the manufacturer pages: Leica, ZEISS and Haag-Streit / Möller-Wedel.

Refurbished ophthalmic microscopes at Medical Elektro

What determines the price of a used ophthalmic microscope?

The price of a used ophthalmic microscope depends on the model, year of manufacture, suspension system and optical and illumination configuration. The XY system and foot control, type of assistant view, camera or recording path and equipment intended for anterior or posterior segment work also affect the valuation. Technical condition, completeness of the set and the scope of work carried out matter as well. Offers should therefore be compared by the actual configuration of the individual unit, rather than by model name alone.

At Medical Elektro, we offer refurbished ophthalmic microscopes. The work required and the cost of parts used vary between units, but every microscope we offer is refurbished to the same standard. Each product is presented with individual photographs and a technical description relating to that specific unit. This makes it possible to check which solutions the device includes and compare it with other microscopes. Every microscope we offer is covered by a 12-month warranty.

The range of procedures performed and requirements for the red reflex, assistant view and suspension system can be considered when choosing a microscope. Currently available devices are shown in the product list. If you are interested in a model that is not currently offered, please contact us.