Figure 1

Figure 2
![Cystatin C concentration in various biological matrices in healthy individuals. Concentration of cystatin C in each biological fluid (mean ± standard deviation [s.d.]; n = 28 [n = 13 healthy controls ≤ 40 years old + n = 15 healthy controls 41–60 years old]), since Table 1 shows a significant increase in cystatin C concentrations in serum and intraocular fluid (IOF) in 61–80 year old healthy controls, and thus, this age group was not included; cerebral spinal fluid (CSF) was obtained from an additional and separate group of cancer-free neurosurgical patients (n = 8) for the determination of the cystatin C concentration as described in the Materials and methods section.
a Significant difference (p < 0.001) from mean values indicated with the same letter.
b Significant difference (p < 0.001) from mean values indicated with the same letter.
c Significant difference (p < 0.01) from mean values indicated with the same letter.
d Significant difference (p < 0.01) from mean values indicated with the same letter.
e Significant difference (p < 0.01) from the mean value indicated with the same letter.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647356294e662f30ba53aaf0/j_raon-2021-0049_fig_002.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKDKQVH6AE%2F20260305%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260305T111346Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEAIaDGV1LWNlbnRyYWwtMSJHMEUCIQDNYo7aOQrTdOJ4QxXzWlPLnV6vZaJ3F5rqlyPrDapxawIgaMFe8jrY1E7bfPRDsK2ueqxJ9kzkJQV%2FzTNbhaxQKl4qxgUIy%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FARACGgw5NjMxMzQyODk5NDAiDOVDa4f7b7CsMQrwHSqaBXuSLq1jXyTA64h5XjdcxhGhNlFuAts1HPG0NMTPHHjKJegZKP4AqbaOpZiwC05zaE%2FEXBPSXy0ToGnpRfyqUyqQKDaN6Ff%2BPmKSwObhAK0cyGAWj6Xlth2JBrgt824dxtwpOxumAt0VgG6UfHON%2Fuw60Qk5X1oPmk5fEii%2BYG73xq%2F2k%2FOFkzVwqwST8CJQO8qt%2FHGgXDxOEGTczFjbccKpV%2B9JyMvABEC8ZQ4UxMmHINLcpiw7Ly90BL1QUwYQA6wqpp5jMfgB%2FUCpiR5UNvZx5bsxSE%2FdrHp%2Fonskh%2F5raLFPUa8qVKjHxC5TPBvONCOIWM%2FIkPvwMWtr%2BahWHPF1pMvOWwgVzjJeUUVSPkfmpr0pk2JU%2FEvMs%2FIjJd0r%2F60dMRgSQ9MDefdVvrbGLs%2FZriEEug3%2FgO1kVJdgGy1Hmcf5Bf4rSRoyRuEBmxqrfTq3hl0Z7ZjHgGx0q6eYfENixQvqxvyZoXojhJRtkntJrJUIiQD2%2FFpn3UlHFFKsFcQ%2Fm0yO3X35O0LtLp2XdDkATqpA9V%2Bdj5AvsDe1maIfJ8nlOpJmYSfXfNM9s40buILL0IiPmeau94Z8uJrAXJjoidamEGKh9Q69MItXAwjdB9WuIGynNJsKtH8Kw4wO8nXmlg08ZQv%2B41HYBZsa3TsPOO8br1oUgzOysnuGJiOM8TdI0hO%2BuWpGnZI4i59P5HeZG7TuKUfI1ST5TS4DMo04t0r7MTsSF89%2B37mHsnxbQ1MoctlERa3UfopWr0S85yDKuj6OnPpTJ%2Bn9ASUMKd1Tr8wffdIh4whqYGKfmDU1oQCwefMEcXm5%2BmVPbi5pG5NmR2i%2BqFywhtaMkr2DShBguTpVG%2BpFORQpSyV6Rv%2BXEmSufKmfROEb%2FTDmnaXNBjqxAb5mVQuZJq%2FXNxgZ%2BWa8HWBLEaycVfvOPb65MeSUkEBUsam3vzIqznIwpL80hOLtBRXeWSTrwWj68sc2FFaDMXkUb6HWeTHVnHGrRACqh0SfXX8W2RkO3U0t%2B3Ohwurcm23FyCBCXx1iMJOoyQDRE8N%2FlqOXJCeRAr8MMCRaDu4rzmg9RTgu4PZnawhCTM0mnyThjRU094MaFfUBUcFdF5RjSkSLCzByBmEYrL2bf5b%2BsA%3D%3D&X-Amz-Signature=955c2084372f234765db2f3eba4f9b2a02cfe5c6858648822666735d0b5d5893&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 3
![Cystatin SN concentration in various biological matrices in healthy individuals. Concentration of cystatin SN in each biological fluid (mean ± standard deviation [s.d.]; n = 28 [n = 13 healthy controls ≤ 40 years old + n = 15 healthy controls 41–60 years old]), since Table 1 shows a significant increase in the cystatin SN concentration in the serum of 61–80 year old healthy controls, and thus, this age group was not included; cerebral spinal fluid (CSF) was obtained from an additional and separate group of cancer-free neurosurgical patients (n = 8) for the determination of the cystatin SN concentration as described in the Materials and methods section.
a Significant difference (p < 0.001) from the mean value indicated with the same letter.
b Significant difference (p < 0.05) from mean values indicated with the same letter.
c Significant difference (p < 0.001) from the mean value indicated with the same letter.
d Significant difference (p < 0.01) from the mean value indicated with the same letter.
e Significant difference (p < 0.001) from the mean value indicated with the same letter.](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647356294e662f30ba53aaf0/j_raon-2021-0049_fig_003.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKDKQVH6AE%2F20260305%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260305T111346Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEAIaDGV1LWNlbnRyYWwtMSJHMEUCIQDNYo7aOQrTdOJ4QxXzWlPLnV6vZaJ3F5rqlyPrDapxawIgaMFe8jrY1E7bfPRDsK2ueqxJ9kzkJQV%2FzTNbhaxQKl4qxgUIy%2F%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FARACGgw5NjMxMzQyODk5NDAiDOVDa4f7b7CsMQrwHSqaBXuSLq1jXyTA64h5XjdcxhGhNlFuAts1HPG0NMTPHHjKJegZKP4AqbaOpZiwC05zaE%2FEXBPSXy0ToGnpRfyqUyqQKDaN6Ff%2BPmKSwObhAK0cyGAWj6Xlth2JBrgt824dxtwpOxumAt0VgG6UfHON%2Fuw60Qk5X1oPmk5fEii%2BYG73xq%2F2k%2FOFkzVwqwST8CJQO8qt%2FHGgXDxOEGTczFjbccKpV%2B9JyMvABEC8ZQ4UxMmHINLcpiw7Ly90BL1QUwYQA6wqpp5jMfgB%2FUCpiR5UNvZx5bsxSE%2FdrHp%2Fonskh%2F5raLFPUa8qVKjHxC5TPBvONCOIWM%2FIkPvwMWtr%2BahWHPF1pMvOWwgVzjJeUUVSPkfmpr0pk2JU%2FEvMs%2FIjJd0r%2F60dMRgSQ9MDefdVvrbGLs%2FZriEEug3%2FgO1kVJdgGy1Hmcf5Bf4rSRoyRuEBmxqrfTq3hl0Z7ZjHgGx0q6eYfENixQvqxvyZoXojhJRtkntJrJUIiQD2%2FFpn3UlHFFKsFcQ%2Fm0yO3X35O0LtLp2XdDkATqpA9V%2Bdj5AvsDe1maIfJ8nlOpJmYSfXfNM9s40buILL0IiPmeau94Z8uJrAXJjoidamEGKh9Q69MItXAwjdB9WuIGynNJsKtH8Kw4wO8nXmlg08ZQv%2B41HYBZsa3TsPOO8br1oUgzOysnuGJiOM8TdI0hO%2BuWpGnZI4i59P5HeZG7TuKUfI1ST5TS4DMo04t0r7MTsSF89%2B37mHsnxbQ1MoctlERa3UfopWr0S85yDKuj6OnPpTJ%2Bn9ASUMKd1Tr8wffdIh4whqYGKfmDU1oQCwefMEcXm5%2BmVPbi5pG5NmR2i%2BqFywhtaMkr2DShBguTpVG%2BpFORQpSyV6Rv%2BXEmSufKmfROEb%2FTDmnaXNBjqxAb5mVQuZJq%2FXNxgZ%2BWa8HWBLEaycVfvOPb65MeSUkEBUsam3vzIqznIwpL80hOLtBRXeWSTrwWj68sc2FFaDMXkUb6HWeTHVnHGrRACqh0SfXX8W2RkO3U0t%2B3Ohwurcm23FyCBCXx1iMJOoyQDRE8N%2FlqOXJCeRAr8MMCRaDu4rzmg9RTgu4PZnawhCTM0mnyThjRU094MaFfUBUcFdF5RjSkSLCzByBmEYrL2bf5b%2BsA%3D%3D&X-Amz-Signature=1ba9bf04f0fd158c781b558ccb63e1db1268d059f38c2bddcc3350d7f88bfdd6&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 4

Figure 5

Concentrations of cystatin C and cystatin SN in biological fluids of healthy individuals as a function of age (Mean ± s_d_)
| Groups | Inhibitor | Serum (ng/mL) | Tears (ng/mL) | IOF (ng/mL) |
|---|---|---|---|---|
| Healthy | Cystatin C | 561 ± 10.0 | 296 ± 11.1 | - |
| (≤ 40 years) [n = 13] | Cystatin SN | 2.24 ± 0.20 | 0.49 ± 0.30 | |
| Healthy | Cystatin C | 539 ± 111 | 256 ± 82.3 | 414 ± 28 |
| (41–60 years) [n = 15] | Cystatin SN | 2.96 ± 0.70 | 0.6 ± 0.35 | 2.7 ± 1.40 |
| Healthy | Cystatin C | a1,341 ± 177 | 382 ± 116 | a844 ± 113 |
| (61–80 years) [n = 9] | Cystatin SN | b4.77 ± 0.10 | 0.75 ± 0.14 | 2.18 ± 0.20 |