The stenopaeic slit is a black disk with a thin slit through it used by optometrists in detecting the level of an astigmatism.[1]

The disk is rotated so that the slit is oriented at different angles, changing the retinal blur size. The stenopaeic slit is more useful to screen for a high degree of astigmatism in patients who have poor vision.

References

edit
  1. ^ Muñoz-Escrivá, L.; Furlan, W. D. (2001-07-01). "The stenopaeic slit: an analytical expression to quantify its optical effects in front of an astigmatic eye". Ophthalmic & Physiological Optics. 21 (4): 327–333. doi:10.1046/j.1475-1313.2001.00582.x. ISSN 0275-5408. PMID 11430627. S2CID 5717844.