Table 1.
Characteristics of the thirteen CSNB2 and nine CSNB1 patients that participated in the study.
Figure 1.
Target locations of the scotopic visual field.
The scotopic visual field locations (black) were based on the locations used in the Esterman test (black and grey). The large diamonds represent the locations that were used to determine the homogeneity of the visual field by comparing the average threshold at 7°, 45°, 60°, and 75°.
Figure 2.
The constructed image of a living room used in the 2D Light Lab.
The image contained 22 everyday objects that varied in size, colour and contrast. The objects were (from left to right and top to bottom): small television, alarm clock, table-lamp, armchair, trashcan, cupboard, bench, coat hanger, vase, plant, playing card, mug, dark table, pencil, white table, telephone, chair, pair of gloves, newspaper, hammer, screwdriver and watch. The left image (A) shows the image at full intensity, the right image (B) shows the image at a low intensity.
Figure 3.
Results of Parts 4 to 7 of the questionnaire.
Top: answers of CSNB2 patients. Bottom: answers of CSNB1 patients. The black horizontal lines indicate the medians. The grey vertical lines extend from the first quartile to the third quartile and thus indicate the range of the mid 50% ranked answers. A black dot is used when the mid 50% ranked date contained one answer only.
Figure 4.
Dark adaptation curves of the CSNB2 patients (A) and CSNB1 patients (B), and a control subject (green curve).
The normal DA curve shows a biphasic form, with an early cone-mediated phase and a later rod-mediated phase. The DA curves of the CSNB2 patients also showed such a biphasic form. Their final thresholds were variably elevated. The DA curves of the CSNB1 patients only showed a cone-mediated phase. Their final thresholds were all approximately 3 log units elevated.
Figure 5.
Scotopic visual field results of the normal subjects, the CSNB2 patients, and the CSNB1 patients.
A: The threshold found at each location of the scotopic visual field, plotted per subject. The open markers represent the average threshold found in that subject. The dashed lines indicate the measuring range, which was 28 to 75 dB in control subjects and CSNB2 patients, and 0 to 47 dB in CSNB1 patients. We found slightly elevated thresholds in CSNB2 patients compared to the thresholds of normal subjects. The thresholds were more elevated in the CSNB1 patients. B: The averaged thresholds of four locations at 7°, 45°, 60° and 75° on the horizontal axes per subject. Thresholds were slightly elevated towards the far end of the visual field in control subjects. We found an equal decline in the control subjects, the CSNB2 and the CSNB1 patients.
Figure 6.
2D Light Lab results of the normal subjects, the CSNB2 patients, and the CSNB1 patients.
A: Three representative examples of the results from the 2D Light Lab. The figure shows the cumulative of the relative number of objects detected or recognized, the fit of the psychometric curve, and the crossmarks that indicate the intensity at which 50% of the objects were detected or recognized (i50d and i50r). B: The psychometric fit to the cumulative of objects detected at increasing light levels in the 2D Light Lab for each subject. The green dots (control subjects), black diamond (CSNB2 patients) and blue triangles (CSNB1 patients) in each fit indicate i50d and i50r. C: The parameters (slope, left) and (i50, right) of the psychometric fit to the 2D Light Lab results of all subjects. Overall we found equal slopes for detection and recognition in control subjects and in CSNB2. However, in the CSNB2 patients the curves were shifted toward higher intensities. The two curves of the CSNB1 patients were steeper, closer together and shifted towards higher intensities compared to control subjects.
Table 2.
Statistical analyses of sloped, sloper, i50d, i50r, and the difference between i50d and i50r (i50r–i50d) between control subjects, CSNB2, and CSNB1 patients.
Figure 7.
Linear regression between the intensity at which 50% of the objects were detected (i50d) or recognized (i50r) and the visual acuity.
The lines resemble the simple linear regression fits. A: The Pearson correlation coefficient for i50d and the visual acuity was R = 0.84, p<0.01 for the CSNB2 patients, and R = 0.41, p>0.05 for the CSNB1 patients. B: The Pearson correlation coefficient for i50r and the visual acuity was R = 0.92, p<0.01 for the CSNB2 patients, and R = 0.86, p<0.01 for the CSNB1 patients.