The document discusses factors that maintain corneal transparency. It notes that transparency is maintained by two key factors: 1) the physical arrangement of corneal layers and 2) the relative dehydration state of the cornea. The epithelium and endothelium play important roles by acting as barriers to fluid diffusion and creating an osmotic gradient to remove water from the stroma. Additional factors like the corneal epithelium, tear film, arrangement of stromal lamellae, and vascularization can also impact transparency when abnormal.

1. CORNEALTRANSPARENCY
ANATOMY OF CORNEA
PART IV

2. FUNCTIONS
OF
CORNEA

3. CORNEALTRANSPARENCY:
MAINTAINENCE OF CORNEAL
TRANSPARENCY OF HIGH DEGREE:
• To perform this function two factors are involved:
1. Physical factors.(corneal layer arrangement )
2. Anatomical factors. (relative state of corneal
dehydration)
• If we upset these two factors than corneal
transparency should get lost to some degree.

4. CORNEALTRANSPARENCYISMAINTAINEDBY:
• The epithelium and endothelium plays a important
role in maintaining corneal transparency by :
1.Serving as mechanical barrier to fluid diffusion .
2.By creating gradient that allows osmotic transport
of water out of stroma.

5. FACTORS
AFFECTING
CORNEAL
TRANSPARENCY.
CORNEAL EPITHELIUM
AND TEAR FILM.
ARRANGEMENT OF
STROMAL LAMALLAE
CORNEAL
VASCULARIZATION

6. CORNEAL
EPITHELIUMAND
TEARFILM.
Normal epithelium is
transparent due to
homogeneity of its
refractive index.
Tight intercellular junctions
account for its
transparency.
As well as its resistance
towards water, electrolyte
and glucose, i.e. BARRIER
FUNCTION.
To maintain normal tear film .
The tear osmolality averages
around 295 mOsmol/L. Which
is isotonic with blood.
And the normal tear breakup
time is generally less than 10
sec.
The abnormality with tear
film is with the dry eye and
Meibomian gland
dysfunction.

7. Arrangementofstromal
lamellae
twotheorieshavebeenput
forwardtoexplainpeculiar
arrangementofstromal
lamellae
Maurice
theory
 State that the loss of
corneal transparency will
result if regular
arrangement of fibrils in a
lattice is separated by less
than a wavelength by
stromal oedema or
mechanical stress.
Theory of
Goldman-
et-al
 After applying diffraction ,
they postulated , that the
cornea is transparent
because the fibrils are small
in relationship to the light
and do not interfere to the
light transmission unless
they are larger than one half
of the wavelength of light
2000 A

8. Corneal
vascularization
 Cornea is avascular
except the small loops
which invade the
periphery about 1mm .
 Various disease
processes of cornea
may be associated
with corneal
vascularisation.
 It brings the defence
mechanism into play
against the noxious
agents .
 It facilitates nutrition,
transport systemic
antibiotics, and drugs.
 If corneal hydration
increases there is a loss
of corneal transparency.
 May be by:
1. Corneal surface
irregularity.
2. Changes in Corneal
thickness.

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