LKC TECHNOLOGIES RETeval - Managing and Using Reference Data

Reference Intervals
RET eval Device User Manual 69
Turning reference data reporting on and off
Reference data reporting can be turned on and off through the user interface and through
custom protocols. Turning off reference data can be useful, for example, if you know that the
subjects you are testing are outside the reference population tested in the database (e.g., testing
subjects significantly outside the age range, testing natural-pupil subjects with constant
luminance protocols, or testing non-human animals).
To see if reference data is currently enabled on the device, follow these steps:
Step 1. Turn on the RET eval device.
Step 12. Select Settings then Reporting then Reference data.
A protocol can set a flag to override this system-default for displaying reference data. Please
contact LKC support for assistance in creating a custom protocol that always shows (or always
doesn’t show) reference data.
Using your own reference data
The reference information database is located on the RET eval device in a folder called
ReferenceData. The database is a text file that can be opened in any text editor (e.g., Notepad,
vi, or Emacs). If you want to add your own reference data information, it can be added to this
file and the RET eval device will automatically start using it. The reference data is version
controlled by the year and week number as specified in the database file, along with the first 7
characters of a cryptographic hash (sha1) of the file. This information is displayed on the PDF
report, so it is clear which reference data set is being used. During firmware updates, the current
reference database will be saved as a backup in the same folder and replaced with a new
reference database. Make backups of any changes you make to the reference database. Please
contact LKC support for assistance in incorporating your own reference data.
The reference data released by LKC is version “2022.01 0c0c194”.
Reference data details
The reference individuals were 309 subjects aged 4 to 85 from 6 trial sites in the United States
and Canada who were carefully examined to have normal vision.
Dark adapted test results came from the Canadian site, which had 42 subjects aged 7 – 64 and
used the protocol ISCEV 6 Step Dark First Td. This cohort has been published (Liu et al. 2018),
although the analysis herein was separately done. These dark-adapted subjects all had the
Troland version of the test, and these values are used in this reference data for both the Troland
and candela version of the tests. All other tests used only the exact protocol in computing the
reference data (i.e., the equivalence of the two stimulation methods was not used / assumed).
Eyes were classified as normal if the following criteria were met: BCVA of 20/25 (0.1 logMAR) or
better, optic nerve cupping < 50%, no glaucoma or retinal diseases, no prior intraocular surgery
(excepting non-complicated cataract or refractive surgery performed more than one year
before), IOP ≤ 20 mmHg, no diabetes, and no diabetic retinopathy as determined by the
ophthalmologist or optometrist.