Trial Lens Set Auxiliary Lenses | Generated by AI
In the context of trial lenses and trial frames used in optometry for eye examinations, PH and BL are abbreviations for specific auxiliary lenses included in a trial lens set. These lenses are inserted into the trial frame to perform various vision tests.
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PH: Stands for Pinhole. This is an opaque disc with a small central hole (typically 1-2 mm in diameter). It’s used to assess whether reduced visual acuity is due to refractive error or a pathological issue by reducing the blur circle on the retina and blocking peripheral light.
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BL: Stands for Occluder (also known as Black Lens). This is an opaque lens used to cover one eye during monocular testing, preventing light from entering the uninspected eye.
These auxiliary lenses are standard components in most trial lens sets (e.g., 158-piece or 266-piece kits) and help in subjective refraction alongside spherical, cylindrical, and prism lenses.
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