An N-spot retinal photography exam means that “N” predefined locations on the retina are examined.
A routine N-spot retinal photography exam is ordered for both eyes. There is nothing unusual observed during the exam, so N pictures are taken of each retina. This healthcare facility also specifies that in an N-spot exam a routine external picture is captured of both eyes, that the current intraocular pressure (IOP) is measured, and that the current refractive state is measured.
The resulting study contains:
2N pictures of the retina and one external picture. Each retinal picture is labeled in the acquisition information to indicate its position in the local N-spot definition. The series is not labeled, each picture is labeled OS or OD as appropriate.
Note: DICOM uses L, R, and B in the Image Laterality Attribute (0020,0062). The actual encodings will be L, R, or B. Ophthalmic equipment can convert this to OS, OD, and OU before display.
In the acquisition information of every picture, the IOP and refractive state information is replicated.
Since there are no stereo pictures taken, there is no Stereometric Relationship IOD instance created.
The pictures may or may not be in the same Series.