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What is Pin hole can reduce refractive error upto - and explain in detail?
Looking through a pinhole reduces the patients refreactive error and improves vision by increasing depth of focus. However, the pinhole vision is limited by diffraction. The opitimal apeure size of a pinhole is 1.2mm, which may correct up to 3D of refreactive error. Reference : Essentials of ophthalmology by Kaiser p.20