HaloGlow variant of the spot retinoscope bulb, German made. Halogen-mimetic light spectrum but in LED spot retinoscope bulb. Unlike the original keeler LED spot bulb, attenuates some of the shortest visible wavelengths to facilitate refraction of photophobic patients or those with media opacities (such as Fuchs’ or cataract) by reducing scatter. Scatter varies (after Rayleigh) according to a fourth power inverse relationship (380nm scatters 16x more than 760nm).

This LED can run off 2.8 or 3.6v power source with the same brightness as the keeler Halogen spot 3.6v bulb. At low rheostat settings it’s brighter (see video) saving battery power.

Reversed vergence (concave mirror) effect bulb. Designed for use with old Heine spot retinoscopes (where the bulb screws into the mount in the neck of the retinoscope), I have found that by modifying the metal housing of the bulb and fitting a base plate, it works perfectly in a keeler professional retinoscope.

Moving the collar up/down does not flip the vergence but with collar fully down the reflex movement is fast (beneficial for an initially dim ret reflex) and sliding the collar up makes the movement slower to aid refining an uncertain end point close to neutral. It could be used with the collar almost always in the position highlighted in the video: project on to wall set at your normal working distance (67cm for +1.50DS), slide collar up until beam becomes crisp circle, this is a nice collar position for everyday refraction.

Reversed Vergence: WITH = ADD MINUS, AGAINST = ADD PLUS, takes a bit of getting used to.

Every bulb has been tested by UK registered optom using a B&L Fischer Schematic Eye.