Figure 5. Electron micrograph and digital images of proteoglycans (PG) of normal, keratoconus (KC), and cross-linked (CXL) corneas. A: Electron micrograph of PGs which are present of normal corneas. B: Digital image is obtained after processing image shown in A, showing variable area distribution of PGs. C: Electron micrograph which are present in PGs of KC corneas. D: Digital image is obtained after processing image shown in C, showing variable area distribution of PGs. E: Electron micrograph of PGs of CXL corneas. F: Digital image obtained after processing image shown in E, showing variable area distribution of PGs. PG=Proteoglycan Proteoglycans color coding: Red=50–350 nm², Green=350–650 nm², Blue=650–950 nm², Yellow=950–1250 nm², Aqua=1250–1550 nm², Pink=1550–1850 nm², Brown=1850–2150 nm².