Table 2.

The results of the proposed method measured against both the reference standard (i.e. the first observer) as well as against the second observer and the results of the second observer against the reference standard. All positioning errors ε are in pixels. From left to right the table shows the percentage of cases in which the structure was successfully located (accuracy), the mean positioning error, the median positioning error, the maximum positioning error, the minimum positioning error, the first quartile and the third quartile. Set 1 are the 500 regular screening images, Set 2 are the regular screening images in which the center of the fovea is inside the FOV and Set 3 are the images containing abnormalities.

Proposed Method vs. Reference Standard
Dataset	Accuracy	ε̄	ε̃	max(ε)	min(ε)	Q1	Q3
Set 1 optic disc	99.4%	8.4	7.2	150.0	1.0	4.2	10.3
Set 2 optic disc	99.4%	8.6	7.2	150.0	1.0	4.3	10.6
Set 3 optic disc	93.0%	20.5	9.9	250.5	1.0	5.8	15.1
Set 1 fovea	93.4%	28.9	6.4	514.5	0.0	3.6	10.7
Set 2 fovea	96.8%	16.1	6.0	514.5	0.0	3.6	9.2
Set 3 fovea	89.0%	25.4	7.3	479.6	0.0	4.5	14.6
Proposed Method vs. Second Observer
Dataset	Accuracy	ε̄	ε̃	max(ε)	min(ε)	Q1	Q3
Set 1 optic disc	99.6%	11.3	9.4	170.7	1.0	6.1	13.5
Set 2 optic disc	99.6%	11.4	9.4	170.7	1.0	6.1	13.5
Set 3 optic disc	93.0%	23.6	10.1	260.5	1.0	6.8	15.0
Set 1 fovea	93.2%	28.4	6.5	502.4	0.0	4.1	12.2
Set 2 fovea	94.8%	21.9	6.4	502.4	0.0	4.1	10.8
Set 3 fovea	87.0%	36.4	7.2	512.7	1.0	5.0	12.2
Second Observer vs. Reference Standard
Dataset	Accuracy	ε̄	ε̃	max(ε)	min(ε)	Q1	Q3
Set 1 optic disc	100.0%	8.3	7.3	43.5	0.5	4.5	10.8
Set 2 optic disc	100.0%	8.3	7.3	43.5	0.5	4.5	10.9
Set 3 optic disc	100.0%	4.8	4.1	16.6	1.0	2.2	6.1
Set 1 fovea	97.8%	7.5	4.3	82.5	0.2	2.7	7.6
Set 2 fovea	98.7%	6.9	4.1	82.5	0.2	2.4	6.9
Set 3 fovea	95.0%	9.6	5.4	67.7	0.0	3.2	10.3