Molecular Vision: Markand, Mol Vis 2016; 22:1291-1308. Table 3

Table 3. Evaluation of OPL at P5. A consistent and the earliest detected morphological difference between WT and KO eyes was found in the OPL.

Average grade of the OPL at P5
WT	KO
2.3	1.3
2.7	2.7
3.0	1.0
3.0	1.3
2.3	2.3
2.0	1.3
2.0	2.0
2.0	3.0
2.7
3.0
2.7
3.0
2.0
3.0
2.7
2.0
Mean ± SD
2.53±0.426	1.86±0.746

The OPL appeared to be more clearly recognizable and continuous in the IRBP KO, while the OPL was less distinctive and less continuous in the WT at P5. Histological cross sections of plastic embedded eyes were cut at about one micron in thickness and stained with toluidine blue. Average OPL grades were collected by three blinded independent observers from independent WT and KO mice at P5. A grading scale from 1 to 3 was used. A score of one corresponds to a fully developed and continuous OPL, while a grade of 3 represents little evidence of any detectable OPL. A grade of 2 represents a partially formed and discontinuous OPL. Each row represents one mouse. A significant difference between the two groups was detected by Mann–Whitney U-test (p=0.041).