The HEINE Miroflex 2 Bifocal Ophthalmoscope is a classic, specialized medical tool used for direct ophthalmoscopy—allowing a doctor or optometrist to look directly into the back of your eye (the fundus) to examine the retina, optic disc, and blood vessels.

While it is an older, vintage model compared to HEINE's modern BETA series, it relies on foundational optical principles that allow the examiner to bypass the patient's iris and see clearly into the eye.

Here is a breakdown of how it works:

1. The Coaxial Illumination System

In normal conditions, if you shine a flashlight into someone’s eye, their pupil shrinks, and the light reflects right back into your eyes, blinding your view.

• The Miroflex uses a coaxial design, meaning the path of the light shining into the patient's eye and the line of sight of the doctor looking out are perfectly parallel and closely aligned.

• A small mirror or prism inside the device head projects a beam of light (powered by a 3.5V handle battery) directly through the patient's pupil, illuminating the retina while allowing the doctor to look through a tiny viewing aperture right above the light beam.

2. The "Bifocal" or "C-F" Selector Switch

What makes the Miroflex distinct from standard ophthalmoscopes is its physical sliding selector (often marked as C-F).

• C (Coarse/Clear): This setting sets the internal lenses for standard, wide-field viewing of the general fundus and retina.

• F (Fine/Macula): This engages a "bifocal" optical shift. It narrows the focus and reduces glare, allowing the practitioner to look directly at the macula (the center of the retina responsible for sharp vision) or to get a higher-contrast, magnified view of fine structures without causing the patient's pupil to constrict heavily from bright light.

3. The Rekoss Disc (Focusing Wheel)

Human eyes have different focal lengths—the doctor might be nearsighted, and the patient might be farsighted.

• To fix this, the Miroflex features a prominent, knurled wheel called a Rekoss disc.

• Turning this wheel rotates a chain of tiny lenses (+ and - diopters) into the viewing path. The doctor clicks through these lenses until the blood vessels at the back of the patient's eye come into crisp focus, compensating for the refractive errors of both individuals.

4. Aperture and Filter Selection

The device features a wheel on the front to change the type of light beam being used:

• Large/Small Spots: For dilated or undilated pupils.

• Fixation Star: Projects a target for the patient to look at, allowing the examiner to map out eccentric fixation.

• Red-Free (Green) Filter: Filters out red light, making blood vessels and hemorrhages stand out as black lines against a green background for easier tracking.