Ophthalmoscope Guide for General Practice

Direct ophthalmoscopy remains a core general practice skill, and the instrument is simpler than the dial of apertures suggests.

What the controls do

Dioptre wheel — compensates for your refractive error and the patient's, and lets you focus at different depths from cornea to retina. A range of roughly −20 to +20 covers general practice.

Aperture selector:

• Large circle — standard, dilated pupils.
• Small circle — undilated pupils, which is most of general practice. Reduces reflection off the iris.
• Red-free (green) filter — makes blood vessels and haemorrhages appear black against the retina. Genuinely useful for nerve fibre layer and vessel detail.
• Slit — assesses elevation and contour of lesions.
• Grid — rough measurement of lesion size.
• Blue filter — used with fluorescein for corneal abrasions.

What matters when buying

Illumination. LED and coaxial optics, which put the light on the same axis as your view, dramatically reduce corneal reflection — the main reason fundoscopy feels impossible through an undilated pupil.

Handle compatibility. Buy a head that fits the handle system you already own, or buy a combined set. See diagnostic sets.

Aperture set. Large, small and red-free covers nearly all general practice. Extra apertures are rarely used outside specialist work.

Practical technique notes

• Darken the room — it dilates the pupil naturally and saves using drops.
• Right eye to right eye, left to left.
• Start at about 30 cm, find the red reflex, then follow it in.
• Ask the patient to fix on a distant point and keep looking at it.

The alternative worth knowing about

Panoptic-style wide-field ophthalmoscopes give a much larger field of view through an undilated pupil and are substantially easier to learn on. They cost more and are bulkier, but if fundoscopy is a routine part of your practice they are worth considering.

Ophthalmoscopes and sets are in diagnostic equipment. See the diagnostic kit guide for the wider room.

Equipment guidance only, not training in fundoscopic interpretation.