A vintage portable trial aperture lens set used by optometrists and ophthalmologists for specialised diagnostic eye examinations with graduated circular aperture discs in green/red and blue/white, this set served multiple clinical functions:​ Primary Uses: Aperture Selection Testing: The graduated circular apertures (ranging from very small to large) were used to test vision through different pupil sizes, simulating various lighting conditions and pupil dilation states.​ Colour Vision and Filter Testing: The distinct green (lime) and blue coloured filter discs were diagnostic tools for: Red-green duochrome testing (the green filters) to refine spherical lens prescriptions​ Colour perception assessment and colour blindness screening Blue light filtration testing for specialised retinal examinations​ Retinoscopy and Fundoscopy Support: These aperture discs would be used in conjunction with ophthalmoscopes and retinoscopes to: Control light beam size during fundal examination (back of the eye)​ Assess patients with varying degrees of pupil dilation​ Test visual acuity under different aperture conditions The graduated sizing allowed practitioners to systematically test how the patient's vision responded to different aperture sizes—crucial for diagnosing conditions like glaucoma, cataracts, and refractive errors where pupil size affects visual performance.​ Age and Dating Circa 1930s-1950s Portable compact format designed for house calls, common before centralised optical practices became standard (1930s-1960s)​ The set also includes a tri part handle and is complete with all contents, unusual for an item of this age.