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=ASIA6AP2G7AKBXMRUHLN%2F20260305%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260305T095155Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEAAaDGV1LWNlbnRyYWwtMSJIMEYCIQDFYxdKUAYc9NlRI1hb%2FiofOc%2BSDL59IJvJDh8nk7S4xAIhAOWo%2FGEPMCEnypust1PwSVcZPNilT7Cz6PHc2zdmBxLJKsQFCMn%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQAhoMOTYzMTM0Mjg5OTQwIgwnJ45zC3nwUXeNTTMqmAVbXdIDeuXm2UULB6coMp5lFKLlRq2dY2FU045sFc%2BfkmeIVoeOixWGQALh2xYPB1C96eSG3eMu99hEmbtnBirURid4O0hjlGR2X9H1xGVqqYpTU3kt%2B6cqiWS4Pb4onYYvYP0qqFs7YJecHHHt0AwEZC1Cv0Jsz9PY4TyPovsiH8cJOVu1pxndTjqyrXby%2FPckz0euxbQQwujnb40WFEDhkCVd2cBAZtGLCT%2BHj0JtUmBdwpEujzBRxQ2X%2FBGPza0D%2BbSDYr94JmREGZOZWvdmCDP0gMBaXW9rK6%2FPIXxEGbTlQGavVFt3qZX35T3tStHxMr%2FDkw4szlYKRC7dgtmtZHKC%2F%2B%2FZk8VQsIsGcOk6ZSoBeFuuezNUuSxrhZwpo2XbRxdHt%2FDkWijhDoCkHdl48Smp%2F00XbDvGLoskQM43bQcvDo0BcSPQKBJTjXWd5qs50rdSCtgFIn%2FvkJUB3r8x%2BvL6kify%2BWlOrz%2FXbkrYmNgB6jLx0r%2FYvZOLUHqXOh2iFLMgNwg4L2xW9l5vudXbHd7f7kaJIjTftf6pSGM%2BeL9SnNzAdhGxXTP%2FWr08bMwIwjfNBTuEl9xmD8qZMAGCn3VW1ULMx%2FXSMBvkDccXVV3mMXwJ5UFEX2WdY5862bwjQIy7KcCsP17m4pp1dEuRTRwlalzspGowrqBtnNdbGHeOEmW%2Bg%2FaNgFCrIblIyUzsADW%2FbT8eTNDsR3qx486SZ4AhUvZkrFLPwZTiNL%2F6tfoPupbG4jNWs7pUBIYFcFiiy5eo4hv%2FuVkHo2iX6TEi%2BfwEt5rrLbw9LitPIvlfgeUDLwXoScXGT%2FPP0HpISmbs2QuIGofshazYirb9UFXg5VUzwbyeproz0rEw7MPvirwK%2F6AG045xMPbfpM0GOrABnBz0Z8ImOHe2NFSeIciNlUXuX%2BAtwWbqHdtJ0WSQq0pILmdTyaH98oZ35%2BIliDrR5YV%2BsgV%2FQD6ehoDMyxLuKOXqjs1gsyX6O1qk%2BiPqITLnxRVUUs7dE9WkQGrI9dlSui3MfFjEJyyZSTH%2BzM%2B88Ljy3SLW4m01pkAC6eMt2pGkB8ZSODvVh1my5Foli6LnAye%2BlWL8J5Zj6o%2FqrSBA%2BoeRQhr23tchaxVn%2B4Ig8Dw%3D&X-Amz-Signature=b535acb3607477c00a716fc6f2f050bb87e4123594b7aeac6f69745610f83c2b&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=ASIA6AP2G7AKBXMRUHLN%2F20260305%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20260305T095155Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEAAaDGV1LWNlbnRyYWwtMSJIMEYCIQDFYxdKUAYc9NlRI1hb%2FiofOc%2BSDL59IJvJDh8nk7S4xAIhAOWo%2FGEPMCEnypust1PwSVcZPNilT7Cz6PHc2zdmBxLJKsQFCMn%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEQAhoMOTYzMTM0Mjg5OTQwIgwnJ45zC3nwUXeNTTMqmAVbXdIDeuXm2UULB6coMp5lFKLlRq2dY2FU045sFc%2BfkmeIVoeOixWGQALh2xYPB1C96eSG3eMu99hEmbtnBirURid4O0hjlGR2X9H1xGVqqYpTU3kt%2B6cqiWS4Pb4onYYvYP0qqFs7YJecHHHt0AwEZC1Cv0Jsz9PY4TyPovsiH8cJOVu1pxndTjqyrXby%2FPckz0euxbQQwujnb40WFEDhkCVd2cBAZtGLCT%2BHj0JtUmBdwpEujzBRxQ2X%2FBGPza0D%2BbSDYr94JmREGZOZWvdmCDP0gMBaXW9rK6%2FPIXxEGbTlQGavVFt3qZX35T3tStHxMr%2FDkw4szlYKRC7dgtmtZHKC%2F%2B%2FZk8VQsIsGcOk6ZSoBeFuuezNUuSxrhZwpo2XbRxdHt%2FDkWijhDoCkHdl48Smp%2F00XbDvGLoskQM43bQcvDo0BcSPQKBJTjXWd5qs50rdSCtgFIn%2FvkJUB3r8x%2BvL6kify%2BWlOrz%2FXbkrYmNgB6jLx0r%2FYvZOLUHqXOh2iFLMgNwg4L2xW9l5vudXbHd7f7kaJIjTftf6pSGM%2BeL9SnNzAdhGxXTP%2FWr08bMwIwjfNBTuEl9xmD8qZMAGCn3VW1ULMx%2FXSMBvkDccXVV3mMXwJ5UFEX2WdY5862bwjQIy7KcCsP17m4pp1dEuRTRwlalzspGowrqBtnNdbGHeOEmW%2Bg%2FaNgFCrIblIyUzsADW%2FbT8eTNDsR3qx486SZ4AhUvZkrFLPwZTiNL%2F6tfoPupbG4jNWs7pUBIYFcFiiy5eo4hv%2FuVkHo2iX6TEi%2BfwEt5rrLbw9LitPIvlfgeUDLwXoScXGT%2FPP0HpISmbs2QuIGofshazYirb9UFXg5VUzwbyeproz0rEw7MPvirwK%2F6AG045xMPbfpM0GOrABnBz0Z8ImOHe2NFSeIciNlUXuX%2BAtwWbqHdtJ0WSQq0pILmdTyaH98oZ35%2BIliDrR5YV%2BsgV%2FQD6ehoDMyxLuKOXqjs1gsyX6O1qk%2BiPqITLnxRVUUs7dE9WkQGrI9dlSui3MfFjEJyyZSTH%2BzM%2B88Ljy3SLW4m01pkAC6eMt2pGkB8ZSODvVh1my5Foli6LnAye%2BlWL8J5Zj6o%2FqrSBA%2BoeRQhr23tchaxVn%2B4Ig8Dw%3D&X-Amz-Signature=b8d1677026ebbdcab1dadd46d8e6708cb3bff94edd462cd86f27e5684dc36d4a&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 |