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1. TEAR FILM
PRODUCTION,CIRCULATION AND DRAINAGE
Group members(Group 1)
Malaka M 20213802
Mashabathakga M.B
202108451
Swanepoel W 202124124
Pholoana B.E 202105532
Nxumalo N 202135070
Malaka M 2021123802
MOPA021
presentation assignment
Lecturer: Ms Khan
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.carlinvision.com%2Fwhat-are-tears-made-of%2F&psig=AOvVaw2CMuiwGQK-
4VteAEZeLxKG&ust=1680144327563000&source=images&cd=vfe&ved=0CBAQjRxqFwoTCIDtjcWPgP4CFQAAAAAdAAAAABAJ

2. FOCUS
• INTRODUCTION
• LAYERS OF THE TEAR FILM
• THE ROLE OF TEARS IN THE EYE
• PATHOLOGIES ASSOCIATED WITH PRODUCTION AND CIRCULATION
• PATHOLOGIES THAT CAN ARISE IN RELATION TO TEAR DRAINAGE
• NEGATIVE EFFECTS OF DEFICIENT OR EXCESS PRODUCTION OF THE TEAR FILM
RELATING TO SECRETION GLANDS
• CONCLUSION

3. Introduction
The tear film
The tear film is a thin fluid layer that covers the outer surface and
serves as the interface between the surface and the outside
world. It provides mechanical, environmental, and immunological
protection, keeps the conjunctival and corneal epithelium healthy,
and makes a smooth, refracting surface for vision. Moreover, the
tear film serves as the corneal epithelium's primary source of
oxygen and serves as a temporary holding area for topical
medicinal medicines.¹
 Characteristics of the tear film²
• Unique, thin, transparent fluid layer covering the ocular
surface
• Highly complex composition of water, electrolytes, mucins,
proteins, lipids

4. Looking at the tears you may think it has only 1
layer…but that’s not true.
-it actually has 3 layers

5. https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.intechopen.com%2Fchapters%2F77585&psig=AOvVaw0
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3
1
2
3
LAYERS OF THE TEAR FILM
• Our tear film is made up of
three layers – an oil (lipid) layer,
a water (aqueous) layer and a
mucin layer. These three layers
work together to help maintain
the health of our eyes and
ward off infection.³

6.  Drainage of the Lipid Layer
occurs through meibomian gland
Orifices allow for removal of excess meibum and debris from glands, which keeps Tear Film healthy3
Lipid Layer •Meibomian glands
•Cholesterol esters
•Waxes
•Delays
evaporation
•Lowers surface
tension
•Provides optically
smooth surface¹
Layer Origin Composition Function 1
 Circulation of the lipid layer
Meibum is pushed out onto the surface of eye with each
blink³
LAYERS OF THE TEAR FILM – LIPID LAYER

7.  Drainage of the Aqueous layer
. This drainage process helps to maintain proper balance of moistures on surface of eye,
allows excess tears to be carried from eye.
Aqueous Layer
•Lacriminal
glands
•Corneal epithelial
cells
•Conjunctival
epithelial cells
•Water
•Oxygen
•Lysozymes,
Lactoferrin,
Betalysin,
Immunoglobins
•VEGF
•Electrolytes
•Barrier to
infection
•Flushes debris
•Wound healing
•Provides energy
for corneal
metabolism
•Corneal
hydration
Layer Origin Composition Function 1
 Circulation of the Aqueous layer
Circulates over the surface of the eye and drains through tiny openings in the corners of
the eyelids called puncta > passes through small ducts into the lacrimal sac (found at the
inner corners of the eye) and eventually into the nose via the nasolacrimal duct
LAYERS OF THE TEAR FILM – AQUEOUS LAYER

8.  Drainage and Circulation of the Mucin layer
Circulation and drainage of tears are facilitated by a series of tiny ducts and channels that lead from eye
to nose
Ducts are collectively known as Drainage System or Lacrimal System
Tears flow from upper and lower towards inner corner of eye, where they are drained through small
openings called puncta > they travel through series of canals into Lacrimal Sac (located near the corner
of eye closest to the nose)
Tears are carried through nasolacrimal duct and drain into nasal cavity
Mucin Layer
•Corneal and
Conjunctival epithelial
cells (Glycocalyx)
•Conjunctival goblet
cells & Glands of Manz
(Mucous)
•Glycoprotein
•Mucin
•Converts corneal
epithelium to a
hydrophilic surface for
aqueous to hydrate.
•Assists Tear Film to
spread evenly and
adhere to eye,
contributing to tear
stability, lowers friction
during blinking and
provides underlying
cornea with
nourishment
Layer Origin Composition Function 1
LAYERS OF THE TEAR FILM – MUCIN LAYER

9. The Role of Tears in the eye
• Tears supports the eyes by keeping them moist and comfortable and
aid in the focus of light, allowing us to see properly. They also protect
our eyes from diseases and irritants such as dirt and dust. Also
prevents dryness by covering the eye's surface and safeguarding it
from external irritants. Since there are no blood vessels on the surface
of the eye, oxygen and nutrients are transported to the surface cells
by tears. Foreign bodies that enter the eye are washed out by tears.5
• Cornea
• Important structure nourished by tears
• Avascular and relies heavily on tears as its main source of nourishment
• The tears contain important nutrients, such as glucose and amino acids –
essential for maintaining health and function of cornea
• Cornea also relies on oxygen from tears for its metabolism

10. Pathologies associated with Production and
circulation of the tear film
Lacrimal secretory and drainage system – keep ocular surface lubricated
Tears produced by lacrimal gland are expelled into nose by lacrimal drainage
system
When tears aren’t working properly – accumulate in eye, lead to excessive crying
or infection
Overproduction of tears by lacrimal gland or blockage of lacrimal drainage
system can result in Epiphora (overflow of tears)7
The nasolacrimal ducts are tear ducts located in the inner corners of each
eye. They drain tears to prevent water buildup in the eyes. These ducts
can become clogged or congested, resulting in severe epiphora. This
condition can affect one or both eyes. Babies, children, and adults are all
affected by this illness.

11. Pathologies associated with Production and
circulation of the tear film
DRY EYE
• Dry eye is a disorder of the tear film caused by tear deficiency or
excessive tear evaporation that causes damage to the interpalpebral
ocular surface and is associated with symptoms of ocular discomfort
From this definition, two major classes of dry eye were established:
tear deficient and evaporative.6
• -Dry Eye (common and excruciating visual condition) – brought on by
localized eye issues, systemic inflammatory disorders, drugs. The
symptoms are now treated, but novel methods may be developed as
our understanding of function of Tear Film improves
• -Dry Eyes (Keratoconjunctivitis Sicca) and Dry Mouth (Xerostomia),
two symptoms of primary Sjogren Syndrome, are brought on by
lymphocytic infiltration of lacrimal and salivary glands9

12. Pathologies that can arise due to tear drainage
Blocked tear duct:
Tear duct draining tears from eye to nose becomes
blocked
Lead to excessive tearing, discharge, and infection
Caused by variety of factors – congenital abnormalities,
infections, trauma, tumours
Dacryocystitis:
Infection of tear sac – small pouch collecting tears before
drained into nose
Lead to pain, swelling, discharge, fever, redness in area
around eye 8
Ectropion:
Lower eyelid turns outward – prevent tears from draining
properly10
Caused by aging, trauma, underlying medical conditions
Entropion:
Lower eyelid turns inward – cause eyelashes to rub against
eye
Lead to irritation, tearing, infection
Caused by aging, trauma, underlying medical conditions10

13. NEGATIVE EFFECTS OF DEFICIENT OR
EXCESS PRODUCTION OF THE TEAR FILM
RELATING TO SECRETION GLANDS
• Tears are vital to health and function
of eyes
• Keep eyes lubricated, clear of debris,
protected from infection.
• Tear Film – composed of several
layers (incl Lipid, Aqueous, and Mucin
Layers) produced by various Secretion
Glands
• Imbalance (deficient and excessive)
in production of Tear Film can lead to
negative effects on eyes

14. • NEGATIVE EFFECTS OF DEFICIENT OR EXCESS PRODUCTION OF THE
TEAR FILM RELATING TO SECRETION GLANDS(cont)
Deficient Production of the Tear Film: Excess Production of the Tear Film:
Dry Eye Syndrome (DES):
- Multifactorial disease of Tear Film and ocular surface
- Symptoms – dryness, irritation, blurred vision.
- Underlying cause – deficiency in Aqueous Layer
produced by Lacrimal Gland.
Reduction in volume or quality of tears produced by
Lacrimal Gland can lead to development of DES.
Watery Eyes or Epiphora:
- Excessive tearing causing discomfort, blurry vision, skin
irritation around eyes
- Underlying cause – overproduction of Aqueous Layer –
caused ocular surface irritation, inflammation,
obstruction of Lacrimal Drainage System.

15. • Tear Film plays crucial role in maintaining health and function of eyes
• imbalance in production of Tear Film can lead to negative effects on eyes
• Lacrimal Gland and other secretion glands must function correctly to maintain optimal eye
health
• Understanding negative effects of deficient or excessive production of Tear Film relating to
secretion glands is essential for diagnosing and treating ocular surface diseases
 As research continues to advance our understanding of tear film and its functions, new
treatments and management strategies will likely emerge, further improving our ability to
care for the health of the eye
CONCLUSION

16. REFERENCES
1. Drew, V.J., Tseng, C.L., Seghatchian, J. and Burnouf, T., 2018. Reflections on dry eye syndrome treatment:
therapeutic role of blood products. Frontiers in Medicine, 5, p.33.
2. Dartt DA, Willcox MD. Complexity of the tear film: importance in homeostasis and dysfunction during disease. Exp Eye Res. 2013 Dec;117:1-3
doi: 10.1016/j.exer.2013.10.008. PMID: 24280033; PMCID: PMC4225770.
3. Refresh,So what is exactly dry eyes. https://www.refreshbrand.com/dryeye/tear-film. Date of access:24 march 2023
4. Napoli, P.E., Nioi, M., Mangoni, L., Gentile, P., Braghiroli, M., d’Aloja, E. and Fossarello, M., 2020. Fourier-domain
OCT imaging of the ocular surface and tear film dynamics: a review of the state of the art and an integrative model of
the tear behavior during the inter-blink period and visual fixation. Journal of Clinical Medicine, 9(3), p.668.
5. Kayal A (2022) The Physiology of Tear Film. Dry Eye Syndrome - Modern Diagnostic Techniques and Advanced
Treatments. IntechOpen. DOI: 10.5772/intechopen.98945.
6. Tasman, William; Jaeger, Edward A.Duane's Ophthalmology, 2009 Edition,2018. https://ophed.net/system/files/2009/07/tear-
film-duanes-ophthalmology-1768-1768.pdf Date of access:05 April 2023
7. "Epiphora: a practical approach to diagnosis and m.anagement" by S. P. Hamada, Eye, 2019
8 Dacryocystitis: Clinical Presentation, Diagnosis, and Management" by M. A. Callahan and R. J. Callahan, American
Family Physician, 2018
9 Dry Eye Syndrome: Diagnosis and Management" by D. A. Schaumberg and D. A. Sullivan, Current Opinion in
Ophthalmology, 2019.
.