Dr. Monika Soni presented on the topic of tear film at the upgraded department of ophthalmology at MGMMC & MYH Indore. The presentation discussed the anatomy and physiology of tear film, including the three layers of the tear film, mechanisms of tear secretion and distribution, functions of the tear film, tests to evaluate tear film such as tear breakup time, Schirmer's test, and osmolarity. A variety of glands contribute secretions to form and maintain the tear film, which is essential for maintaining a clear cornea and proper vision.

1.  MODERATOR:DR.SHWETA WALIA
 PRESENTER:DR. MONIKA SONI
[ 1st YEAR RSO ]
UPGRADED DEPARTMENT OF OPHTHALMOLOGY
MGMMC & MYH INDORE

3.  The Value of tear fluid in preserving a clear cornea has
been understood since ages.
 Blinking action of lids was essential for spreading the tear
& maintaining a moist surface was obvious even in old ages.
 Presence of precorneal layer of liquid was first
demonstrated by: FISCHER [1928]: Reflectography.
 ROLLET : Described it as the most superficial, sixth layer of
cornea.

4. Lipid -secreted by
Meibomian glands -situated in upper and
lower lid margins
Gland of Zeis –situated near base of eye lashes
 Aqueous- secreted by
Lacrimal gland - it consists of an upper orbital
&lower palpebral part .
 orbital part ;situated in fossa for lacrimal gland at
the outer part of orbital plate of frontal bone.it is
larger about the size & shape of a almond.
 Palpebral part: it is small & consist of only one
or two lobules.
Glands of Krause -situated in the conjunctival
mucosa near the fornices, approximately 40-42 in
upper lid and 6-8 in lower lid

5. Cont…
Glands of Wolfring -situated near the upper border
of the superior tarsal plate &lower border of inf. tarsus
2-5 in no.
Mucous secreted by
Goblet cells –situated in the epithelium of
the conjunctiva.
Crypts of Henle –Invagination of superior
peripheral conjunctiva near the superior
fornix

6.  Mechanisms
 Normal and voluntary eyelid action, with each blink.
IACLE Module 1, page 67

7. Tears
Upper and lower puncta
Upper & lower canaliculi
Lacrimal sac
Naso-lacrimal duct
Nose(valve of hasner)

8.  WOLF[1946]: First describe the structure of tear film.
 He coined the term “ PRECORNEAL FILM”.
 He assumed that it consist of three layers:
 An outer oily layer.
 An intermediate aqueous layer.
 An inner mucoid layer.

10.  Derived from secretions of Meibomian, Zeiss & Moll
glands, cover the entire free surface of the tear fluid.
 WOLFF called it “MARGINAL TEAR STRIP”
 Chemically this layer mainly consists of lipids
having low polarity: Wax & Cholesterol esters. High
polarity lipids: Tg, FFA & phospholipids are
presents in negligible amount.
 Thickness of this layer is about .1µm

11.  Middle layer :secreted by Lacrimal gland & accessory
glands of Krause & Wolfring .
 Main bulk of tear film constituted by this film ; 95
%→60 %.
 The film covering the cornea is considerably thinner than
over the conjunctiva.
 This layer is an aqueous solution of low
viscosity, containing ions of inorganic
salts, glucose, urea, enzymes, protein& glycoproteins.
 Lysozyme, lactoferrin,TSP &secretory immunoglobulin-
A are main protein fraction.
 Buffering capacity of tear fluid is b/o bicarbonate ions &
proteins.

12. Mainly secreted by conjunctival goblet cells, crypts of Henle &
the glands of manz.
 Clear corneal epi. Is a relatively hydrophobic surface.
 Mucin mixed & spread by action of lids ,gets adsorbed on the
cell membrane of epithelial cells & anchored by their microvilli
forming a new hydrophilic surface on which aqueous & lipid
layer spread spontaneously.It thus play a vital role in stability
of tear film.
 Holly & Lemp consider it as the third layer of tear film

13. Functions of tear film
Lipid Layer
 To prevent evaporation of aqueous layer and
maintain tear film thickness
 As surfactant
Aqueous layer
 Provide atmospheric oxygen to the corneal
epithelium
 Atibacterial activity
 To wash away debris and noxious stimuli
 To provide smooth optical surface to the cornea
Mucin layer
 Convert corneal epithelium from a hydrophobic
to a hydrophilic surface.
 adhesion to the corneal surface
 responsible for maintaining the stability

14.  Tear fluid is clear ,salty ,slightly alkaline & watery.
1.Thickness of tear film :average thickness 4-8µm.
2.Volume : 7µl[4-13µl].Highest in youth & 10% of
youth value by age of 70 yrs.
3.Rate of tear secretion: 1.2µl per min. Total 24hr
secreting volume:10cu ml.

15.  4. Turn over rate:18% per min.
 5.Refractive index:1.357.
 6.pH of tear:about 7.4[7.3-7.7]. Tear pH is lowest on
awakening d/t acid by product of anaerobic
condition & increases on eye opening d/t loss of
CO2.
Age,Sex ,time of examination,+nce of Pterygium &
Pinguecula have little effect on ph.
inflammatory cond. Of cornea &conjunctiva
decreases pH.
.

16.  Osmotic pressure: 2mmhg[higher than aquous
humor 0.1 & lower than plasma 25mmhg].
Optical integrity of the cornea is significantly
influenced by tonicity of tear .o.p. significantly
changed with reflex stimulation of tears.
 osmolarity: 300-310 mosm/l [0.9%NaCl aq. Sol.]
More osm. of tear more severe is dry eye.
Oxygen tension: 40- 160 mmhg.

17.  HORMONAL-
1.androgens are the prime hormones that regulate lipid
production
2.Oestrogen & progesterone receptors in conjunctiva
&lacrimal gland are essential for normal function of
these tissue
 NEURAL-
neural fibers adjacent to the lacrimal gland & goblet
cells result in aqueous &mucus secretion

19.  The primary role of tear film is to establish a
refractive surface of high quality for the cornea & to
ensure the well being of the cornea & conjunctiva.
 Tear film accomplishes its functions by the highly
specialized &well-organized dynamic activities:
1. Secretion of tears.
2.Formation of tear film.
3.Retention & redistribution of tear film .
4.Displacement phenomenon.
5.Evaporation from the tear film.
6.Drying & break up of tear film .
7.Dynamic events during blinking.
8.Elimination of tear.

20.  Tears are continuously secreted throughout the day by
accessary(basal secretion) & main (reflex secretion) lacrimal
glands.
 Concept of “basal tear secretion” is thought to be now obsolate.
 Even minimal tear secretion in undisturbed eye is thought to
be secondary to light or temperature stimulation or both.
 Afferent pathway of this secretion is formed by Fifth nerve &
efferent by parasympathetic(secretomotor) supply of lacrimal
gland.
 82% of full term newborn secretes tear within 24 hrs and 95%
by 1st week
 Abnormal tearing start only after 4 months- b/o low
innervation of cornea

21.  Corneal epithelium is a relatively hydrophobic surface
 Lemp and holly found that principal constituent of tear
mucin responsible for wetting of corneal surface by
converting the corneal surface from hydrophobic to
hydrophilic one.
 Sequence of events in formation of tear film
a. Lids surfacing cornea with a thin layer of mucus
b. On this new surface, aqueous component of tear now
spreads spontaneously
c. Superficial lipid layer spread over the aqueous film
contributing to its stability and retarding evaporation
between blink

22.  Tear film is retained at a uniform thickness over
the corneal surface against a gravitational force
– wolff 1954
 Outermost layer of the corneal epithelium and
mucopolysaccharides play an important role in
retaining tear film
 The fluid in the tear film is stagnant unless it is
mixed by blinking and eye movements with the
tear fluids in the marginal strip

23.  Surface of the cornea is covered by a film
possessing a certain stability compressibility
and elasticity which is almost unaffected by
gravity
 This property is responsible for movement of
particle in the film when lower lid is displaced
upwards.

24. All lipids in the tear film including wax ester and
cholesterolester retards the evaporation of the
tear
 Evaporation of the tear film is estimated to be
10% of the production rate(1.2µl/min)
 Air motion has no effect on the evaporation rate
because resistance to evaporation is mainly due
to oily layer in tear film

25.  In humans the tear film has a short lived
stability

Normal tear film breakup time is 15-40
secs,when blinking is prevented the tear film
ruptures and dry spot appear.

26.  When eyes open there is relaxation of orbiculris oculi
 Canaliculi and sac expand, creating negative pressure
 Draws the tear from the eye into empty sac
 When eye closes , contraction of pretarsal orbicularis
oculi
 Compression of ampulla and horizontal canaliculi

27.  Simultaneously , contraction of lacrimal part of
orbicularis oculi ( horners muscle)
 Compression of sac , creating positive pressure
 Tears flows down into the NLD & then into nose.

29.  Tear break up time  Conj. Scrapping
• Schirmer test  CIC
 phenol red thread test  Ph
 Tear lysozyme assay  Tear evaporation rate
 Tear lactoferrin assay  Tear fern test
 Flouresene test  Flurophotometry
 Rose bengal staining  Tear osmolarity
 Tearscope

30. 1.Tear film breakup time - It is abnormal in
aqueous tear deficiency and meibomian gland
disorder.
 2% flouorescein is instilled in lower fornix, and ask pt.
to blink several times.
 Tear film is examined at the slit lamp with a broad
beam using the cobalt blue filter.
 After an intrval, black spot or lines appears in the
fluorescein stained film-dry areas

31.  TBUT is the interval b/w the last blink and the
appearance of the first randomly distributed dry spot.
 Normal TBUT: 15 to 45 seconds.
 No significant relation between age,sex,corneal
sensation,palpebral fissure width,IOP,humidity or
temp. with TBUT found.
 A significant decreae in TBUT-on holding lids aparts.
 TBUT decreaded significantly after use of
BENZALKONIUM CHLORIDE & TOPICAL BETA
BLOCKER,CIGARETTE SMOKE.
 TBUT <10 sec is abnormal.

33. 2. Schirmer’s test - For tear quantity
Done with a strip of filter paper measuring 5 by 35 mm
-Type-I –Done by placing the strip on lower fornix at
the junction of outer 1/3 and inner 2/3
for 5 mins.
More than 15mm of wetting in 5 min.-normal.
Whatman filter paper 41 now standered.
-gives the value for basic and reflex secretion of tears
*Basal secretion test– conjunctiva is anaesthetized
before performing the test

34. -Type-II
- to know basal secretion of tears
-Done by stimulating unanaesthetised nasal mucosa
by cotton tip, and note the wetting aft 2 min.
-This is seldom used
 Normal wetting is 15mm
 <5mm indicates severe KCS

35.  Type III-
-To know the reflex secretion
-ask the pt. to look directly in sun
-no diagnostic value, and is potentially dangerous.

36.  Modification of Schirmers test-
# Jones multiplied the distance of wetting of standard
strip placed for 1 min by a factor of 3 &found it to
correlate with a 5 minute reading
#A modified schirmer test in which the standard strip
intended to be placed for 5 min was moved to a
different place if there was no wetting aft 1st 2 min, has
been reported to obviate false positive results.

37. 3.Phenol Red thread test –obviate the disadvantage of
schirmer ‘s test by eliminating the need for anesthesia.
more efficient than filter paper.
 fine dye impregnated 75mm cotton thread is placed
at the point of 1/3 distance from lateral canthus with
eye in primary gaze for 15 sec.,alkalinity changes its
colour to bright orange from tear contact.
 10mm or less indicate dry eye.
.

38. Tear lysozyme assay - Most often tear lysozyme decreases
before dry eyes are clinically evident. So it is of great
diagnostic &prognostic value.
Not popular
4.Lactoferrin radial inmmuno diffusion assay –major
protein secreted by lacrimal glands.performed using
readily available kits
-it is more sensitive &specific than any other test.
-In milder cases, should be combined with schirmers test.
Amt.of this molecule is closely resembles to tear
production.
Tear lactoferrin decreased in sjogren synfrome.

39. 5.Flourescein clearance Test
5micro lt. of flouorescein on the ocular surface&
measuring the residual dye in shirmer strip at
interval of 1,10,20&30 mins. {under blue light using
florophotometry}
in normal eyes the values will have fallen to zero
after 20mins.delay clearance is observed in dry eye.
6. Tear osmolarity -normal value 302±6.3 mOsm/l
-in KCS osmolarity increases(330 to 340 mOsm/l)
-It is measured with 0.2 micro lt of tears, by
measuring freezing point depression.
- it is very specific diagnostic test for KCS

40. 7.Conjunctival scraping - stains with giemsa stain -in
dry eyes it shows numerous goblet cells with pink
cytoplasm and nucleus on one side of cell.

41. 8.Conjunctival impression cytology -
 It is a substitute for conjunctival biopsy.
 It is simple, easy, reliable, accurate, low cost, non
invasive technique which can be repeated as often as
required.
 Abnormal pattern precedes the ocular signs of
xerophthalmia.

42.  It is to identifying the pathological changes occurring
in conjunctiva i.e. squamous metaplasia.
 Technique-
1.samples are collected on Millipore cellulose acetate
paper strips (3×10mm size with a diagonal edge).
2.Paper is applied near the limbus on the bulbar
conjunctiva inferonasally and inferotemporaly.
3.kept for 3-5 sec , then removed with peeling motion
by using glass rod and forcep.

43. 4.specimens are dropped into fixative sol. (ethyl
alcohol, formaldehyde,and glacial acetic acid in 20:1:1
volume ratio )
5.stained with PAS and HEMATOXYLIN or PAS &
MODIFIED PAPANICOLAOU’S stain.
6.Examined under light microscope & staged according
to the degree of squamous metaplasia, the finding on
conjunctival impression cytology have been graded
according to the severity of dry eye state from 0 to 5 as
follows

44. Stage 0: normal cellular structure
Stage 1: early loss of goblet cells without
keratinisation
Stage 2: total loss of goblet cells with slight
enlargement of epithelial cells
Stage 3: early and mild keratinisation
Stage 4: moderate keratinisation
Stage 5: advanced keratinisation

45. - Marginal tear strip characteristics :
Marginal tear strip or tear meniscus is a
continuous, full and slightly concave meniscus formed
by the tears between the eyelid margin and the inferior
bulbar conjunctiva
- A height of 0.5mm of tear strip is considered a normal
Scanty, discontinuous or absent tear strip is an
important sign of dry eye.

46. 10.pH ( hydrogen ion concentration)
- Normal range 7.3 – 7.7
- KCS patient exhibits slight alkaline shift in pH which
was statistically insignificant
11.Tear evaporation rate
- Rolando and refojo devised a tear evaporimeter
- Significant increased rate of evaporation is found in
conditions like KCS, SJS, ocular pemphigoid and
meibomitis
- The instrument complex for routine diagnosis serve as
a noninvasive diagnostic and research tool.

47.  TEAR FERN TEST -1.tears when dried on slide shows
ferning.
2.classified in the 4 group:
A. Uniform arborisation and numerous branching are
seen. little or no space between ferns.
B. Branching is less and there is abundent space between
ferns.
C. Ferns are thicker and smaller with little branching
and very large spaces between them.
D. No ferning but amorphous patter is seen.

48. 3.Pattern A is normal while D suggests severe disease.
Pattern C and D are associated with lack of lactoferrin
and lysozymes in tears, prone to frequent infections.

49.  Fluophotometrey is considered a laboratory or research
technique rather than a clinical technique
 Measuring the thickness of the tear film
 Assessing the tear fluid turn-over in normal and contact
lens- wearing conditions
 Assessing the the permeability of the cornea in general and
its component layers in particular in
 The normal eye
 The diseased eye
 the dystrophic eye
 The contact lens wearing eye
 Determination of corneal pH

50.  It uses a cold light source to minimize any
drying of the tear film during the examination.
 It can be used directly in front of the eye or in
conjunction with a slit-lamp biomicroscope to
gain more magnification.
 Evaluation of the interference patterns of the
anterior surface of the tear film lipid layer
facilitates the diagnosis of the cause of dry eye
symptoms, as well as screening patients for
contact lens wear.
 It also allows the measurement of the non-
invasive break-up time.

51.  FLUORESCEIN STAINING –
 Recorcinolphthalein with MW 376.27,orange red
hygroscopic poweder producing intense green
fluorescent colour at pH>5.
 large molecule unable to traverse normal corneal
epithelium tight junctions .
 Shows area of denuded corneal epithelium and
Punctate staining of cornea

52.  Pattern of srain;
interpalpebral staining of
cornea & conj. Is common
in aquous tear deficiency
 sup. Conj. Staining –sup.
Limbic
keratoconjuctivitis
 Inf.corneal &conj.
;blepheritis & exposure
keratitis.

53.  ROSE BENGAL STANING
- Derivative of flouorescein
- Affinity for dead and devitalized epithelial cells that
have a lost or altered mucous layer
- 1%sol. Or a moistened impregnated strip
Stains damaged conj. And corneal epithelium, mucus
threads and filaments as readily visible red color
 .

54. - bijsterveld found the dye to be very useful in diagnosis
of KCS
- He suggested a grading system of rose bengal staining
in which palpebral aperture was divided into 3
areas, nasal and temporal conjunctiva and the cornea.
- A score of 0 for absent,1 for just present, 2 for
moderate staining and 3 for gross staining.
- Total score of 3.5 of 9 considered abnormal

55. False-positive staining may occur in
conditions such as chronic
conjunctivitis, acute chemical
conjunctivitis secondary to hair spray use
and drugs such as tetracaine and
cocaine, exposure keratitis, superficial
punctate keratitis secondary to toxic or
idiopathic phenomena, and foreign bodies
in the conjunctiva.

56.  Lissamine green staining:
- Dark green water soluble substance
- Norn first employed the dye for vital staining of the
cornea and conjunctiva
- He employed 1% soln and found that lissamine green
has vital staining properties almost identical with that
of rose bengal
- It is less irritating as compared to rose bengal

57.  Dry Eye is a multifactorial
disease of the tears & ocular
surface that results in symptoms
of the discomfort, visual
disturbance, & tear film
instability with potential damage
to the ocular surface

58. Dry eye
Aqueous deficient evaporative
Sjögren syndrome dry eye Non-Sjögren syndrome dry eye Intrinsic Extrinsic
Mebiomian oil
Primary Lacrimal deficiency Vitamin-A deficiency
deficiency
Lacrimal duct Disorder of lid Topical drugs
Secondary
obstruction aperture preservatives
Reflex block Low blink rate Contact lens wear
Systemic drug Occular surface
disease
e.g.- allergy

59.  Increased discomfort after periods of reading, watching
TV, or working on a computer.
 The symptoms of dry eye syndrome include persistent
 Dryness
 Redness
 Scratching
 Irritation
 Burning
 Often people with this condition may experience a feeling
that something is in the eye.

60. Though dry eyes cannot be
cured, there are a number of steps that
can be taken to treat them. Treatments
for dry eyes may include:
 Artificial tear drops and ointments
 Temporary punctal occlusion
 Permanent punctal occlusion
 Other medications
 Surgery
 Natural remedies

61.  Almost all are of aqueous substitutes.n0 mucus
substitutes .paraffin is only approx.to the action of tear
lipids.
 Drops & gels; cellulose derivatives [0.25-1%
methyl cellulose.& hypermellose]
 Carbomers :adhere to the ocular surface & so are
long lasting.
 Polyvinyl alcohol: increase the persistence of tear film
 Sodium hyluronate: promotes conj.& corneal healing

62.  Acetylcysteine [5%] drops may help in dispersing the
mucus threads & decreasing the tear viscocity.

63.  Low dose of topical steroids : very effective in acute
exacerbation.
 Topical cyclosporines[0.05-0.1%]: very effective drug
.reduces t-cell mediated inflammation ,resulting in
increase no. of goblet cells & reversal of squamous
metaplasia.
 Systemic tetracyclines: may controls associated
blepheritis & reduces inflammatory mediators .

64.  Useful in reversing the cellular changes in conj.of dry
eye.[squamous metaplasia]

65.  Temporary punctal occlusion. Sometimes it is
necessary to close the ducts that drain tears out of the eye.
This is first done via a painless test where a collagen plug
that will dissolve over a few days is inserted into the tear
drain of the lower eyelid to determine whether permanent
plugs can provide an adequate supply of tears.
 Initially the inferior punctal occlusion done.
 Permanent punctal occlusion. If temporary plugging of
the tear drains works well, then silicone plugs (punctal
occlusion) may be used. The plugs will hold tears around
the eyes as long as they are in place.

66.  Low water content HEMA lenses : moderately dry eyes
 Silicone rubber lenses: no water & transmits oxygen
.very effective in protecting cornea in extreame tear
fillm deficiency,although deposition of debris on
surface of lens may blur the vision.
 Occlusive gas permeable lenses: provides a reservoir of
saline over the cornea.

67.  Reduction of room temprature
 Room humidifiers
 tarsorrhaphy

68.  Botulinum toxin injection :may control s the
blepherospasm in severe dry eye
 Zidovudine: may be beneficial in primary
sjogren syndrome.
 Submendibular gland transplantation; for
extreme degrees of dry eye

69.  Vitamin A: cod liver oil, liver, carrots, sweet
potatoes, butternut squash.
 Lutein and
zeaxanthin: spinach, kale, collard greens.
 Vitamin C: strawberries, broccoli, oranges,
 Bioflavonoids: citrus
fruits, cherries, grapes, plums.
 Vitamin E: sunflower
seeds, almonds, hazelnuts.
 Selenium: brazil nuts, yeast, seafood.
 Zinc: oysters, hamburgers, wheat, nuts
 Fatty acids: cold-water fish

70.  Omega-3
 Flaxseed Oil
 Vitamin A (Beta Carotene)
 Hyaluronic Acid
 N-Acetyl-L Cysteine
 Evening Primrose Oil
 Glucosamine and Chondroitin
Sulfate

71. Thank you