Table 1

Alterations seen in the aging cornea

CharacteristicResult of change
(1) Changes in shape and optical properties(i) Steepening of keratometry and a shift from with the rule to against the rule astigmatism38 39
(ii) Transparency is unaffected in central cornea in absence of scar or degeneration40
(iii) Collagen intramolecular and interfibrillar spacing increases—possibly via increased protein glycation41 42
(iv) Increased thickness of Descemet’s membrane
(2) Corneal degenerations (influenced by environmental and genetic factors)(i) Cornea farinata
(ii) White limbus girdle
(iii) Mosaic degeneration
(iv) Deep crocodile shagreen
(v) Hassall–Henle bodies
(vi) Arcus senilis
(3) Physical properties(i) Resistance to infection reduced
(ii) Failure to upregulate ICAM-1 and reduced inflammatory cell infiltration43
(iii) Reduced phagocytically active cells after infection44
(iv) Decline in high energy metabolism45
(v) Increased tear contact time46
(vi) Increased epithelial permeability to flourescein47