Question:medium
Corneal transparency is maintained by which of the following glycosaminoglycans (GAGs)?
Corneal transparency is maintained by which of the following glycosaminoglycans (GAGs)?
Show Hint
Think about which glycosaminoglycan is unique to the corneal stroma and controls collagen fibril spacing.
Updated On: Jun 23, 2026
- Hyaluronic acid
- Chondroitin sulphate
- Keratan sulphate
- Heparan sulphate
Show Solution
The Correct Option is C
Solution and Explanation
The corneal stroma is a highly organised matrix of type I collagen fibrils embedded in proteoglycans. Corneal transparency depends on the precise uniform spacing of collagen fibrils (~60 nm apart), which causes destructive interference of scattered light.
The dominant glycosaminoglycan in the corneal stroma is $\text{keratan sulphate}$, carried by proteoglycans such as lumican and keratocan. Keratan sulphate chains regulate fibril spacing; when these chains are abnormal or absent (e.g., in macular corneal dystrophy due to CHST6 mutations), fibril spacing becomes irregular and the cornea becomes opaque.
Other GAGs compared:
- Hyaluronic acid: vitreous humor, synovial fluid -- not cornea
- Chondroitin sulphate: cartilage, minor corneal component
- Heparan sulphate: basement membranes, liver
\[\boxed{\text{Keratan sulphate}}\]
The dominant glycosaminoglycan in the corneal stroma is $\text{keratan sulphate}$, carried by proteoglycans such as lumican and keratocan. Keratan sulphate chains regulate fibril spacing; when these chains are abnormal or absent (e.g., in macular corneal dystrophy due to CHST6 mutations), fibril spacing becomes irregular and the cornea becomes opaque.
Other GAGs compared:
- Hyaluronic acid: vitreous humor, synovial fluid -- not cornea
- Chondroitin sulphate: cartilage, minor corneal component
- Heparan sulphate: basement membranes, liver
\[\boxed{\text{Keratan sulphate}}\]
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