BRIEF DISCUSSION OF TEAR FILM DYNAMICS

1. TEAR FILM DYNAMICS
DR ASHISH BADGUJAR

2. THE TEAR FILM
• THE MAIN ROLE OF LACRIMAL SYSTEM IS TO
ESTABLISH & MAINTAIN A CONTINUOUS TEAR
FILM OVER THE OCULAR SURFACE.
• THE PRESENCE OF THE PRE-CORNEAL TEAR FILM
WAS 1ST DEMONSTRATED: BY FISCHER IN 1928.
• ROLLET DESCRIBED IT AS THE MOST SUPERFICIAL
6TH LAYER OF CORNEA.

3. STRUCTURE OF THE TEAR FILM
• WOLFF WAS THE 1ST TO DESCRIBE IN DETAIL
THE STRUCTURE OF THE TEAR FILM.
• COINED THE TERM ‘PRE-CORNEAL FILM’.
• TEAR FILM CONSISTS OF 3 LAYERS.
1)OUTER LIPID LAYER
2)INTERMEDIATE AQUEOUS LAYER
&
3)INNER MUCIN LAYER

4. TEAR FILM…..

5. LIPID LAYER…
• IT IS THE OUTERMOST SUPERFICIAL LAYER
• DERIVED FROM SECRETION OF MEIBOMIAN, ZEISS & MOLL GLANDS,
• IT IS HOLOCRINE SECRETION
• MARGINAL TEAR STRIPS
• CHEMICAL- IT IS MADE OF LOW POLARITY LIPIDS (WAX, CHOLESTEROL
ESTERS)
• MINIMAL HIGH POLARITY LIPIDS (TG, FREE FATTY ACIDS,
PHOSPHOLIPIDS)
• BRAUNINGER ET AL- EXISTENCE & PHYSICAL INTEGRITY
• THICKNESS- 0.1MICROMETRE
• FUNCTION- PREVENTS OVERFLOW OF TEARS & RETARDS THEIR
EVAPORATION.

6. AQUEOUS LAYER…
• MIDDLE LAYER
• SECRETED BY MAIN & ACCESSORY LACRIMAL GLANDS.
• THICKNESS- 10 MICROMETER
• IT IS A AQUEOUS SOLUTION OF LOW VISCOSITY, CONTAINING IONS OF
INORGANIC SALTS, GLUCOSE, UREA & BIOPOLYMERS LIKE ENZYMES,
PROTEINS & GLYCO PROTEINS.
• HAS BUFFERING CAPACITY BECAUSE OF BICARBONATE.
• FUNCTION-
1. PROVIDES ATM O2 TO EPITHELIUM
2. WASHES AWAY DEBRIS & NOXIOUS IRRITANTS
3. CONTAINS ANTIBACTERIAL SUBSTANCES LIKE LYSOZYME & BETALYSIN

7. MUCUS LAYER….
• DEEPEST PART OF STRATUM WHICH IS HIGHLY HYDRATED, SEMISOLID
• IT PLAYS A VITAL ROLE IN STABILITY OF TEAR FILM
• SECRETED BY CONJUNCTIVAL GOBLET CELLS, CRYPTS OF HENLE & GLANDS OF
MANZ
• THICKNESS-30 MICROMETER
• CORNEAL EPITHELIUM IS HYDROPHOBIC, THIS MUCIN THAT IS PRODUCED GETS
ADSORBED ON CELL MEMBRANE OF EPITHELIAL CELLS & ANCHORED BY THEIR
MICORVILLI TO FORM A NEW HYDROPHILIC SURFACE ON WHICH AQUEOUS &
LIPID LAYERS CAN SPREAD
• FUNCTION-
a) VITAL ROLE IN STABILITY OF PREOCULAR TEAR FILM
b) LUBRICATES OCULAR & PALPEBRAL SURFACE

8. IN BRIEF
LIPID
•MEIBOMIAN,
ZEISS & MOLL
GLANDS,
•0.1 microm
•Retards
evaporation
AQUEOUS
•Main &
accessory
lacrimal
glands
•10
micrometer
•Diffusion of
atmospheric
oxygen
MUCIN
•conjunctival
goblet cells,
CRYPTS OF
HENLE &
GLANDS OF
MANZ
•stability

9. STRUCTURE OF TEAR FILM…..
Lipid layer – 0.1micrometer
Aqueous layer – 10
micrometer
Mucin layer –
30
micrometer

10. FUNCTIONS OF TEAR FILM….
1. OPTICAL SURFACE OF CORNEA
2. KEEPS SURFACE OF CONJUNCTIVA & CORNEA
MOIST
3. SERVES AS LUBRICANT
4. TRANSFERS OXYGEN FROM AIR TO CORNEA
5. PREVENTS INFECTION D/T PRESENCE OF
ANTIBACTERIAL SUBSTANCES
6. WASHES AWAY DEBRIS & IRRITANTS

11. • THICKNESS- PREVIOUSLY: 4-8 UM, IT IS THICKEST AFT BLINK IE 9UM & THEN
DECREASES IN LINEAR MANNER UNTIL 30 SEC WHERE IT DECREASES TO 4 UM.
• CONFOCAL MICROSCOPY: 40UM THICK.
• VOLUME- 7 MICROLITER (4-13 MICROLITER), IT IS HIGHEST IN YOUTH &
THEN GRADUALLY DECREASES AS AGE ADVANCES & IS ASSOCIATED WITH S/S
OF DRYNESS.
• RATE OF SECRETION-1.2MICROLIT/MIN, TOTAL 24HRS VOL IS 10ML.
• TURN OVER RATE- 18% /MIN. SINCE THE TURN OVER RATE IS HIGH, RESULTS
IN POOR RETENTION OF INSTILLED MEDICATION.
PHYSICAL PROPERTIES OF TEAR FILM

12. • PH- 7.4 (7.3-7.7), HENCE INSTILLATION OF SOLUTIONS OF PH<6.6 &
>7.8 RESULTS IN DISCOMFORT.
• OSMOTIC PR.- 0.9-0.95% NACL SOLUTION.
• RI- 1.357.
• TEMPERATURE – 35 DEGREE AT THE LIMBUS TO 30 DEGREE AT THE
CENTRE OF THE CORNEA
• OXYGEN TENSION -40 TO 160 MM HG
• CONTACT LENS – LESS THAN 20 MM HG

13. CHEMICAL COMPOSITION OF TEARS
WATER+SALTS+LOW MOLECULAR WT. SUBSTANCES
1. WATER- LARGEST PART- 98.2%, DISSOLVED SOLIDS-1.8%
2. PROTEINS- 0.6- 2 GM%
• GROUP A – SIMILAR TO SERUM PROTEINS
• < 15 % OF ALL TEAR PROTEINS
• IGG, ALB, TRANSFERRIN, ALPHA- 1 ANTITRYPSIN, ALPHA-1
ANTICHYMOTRYSIN, BETA2 MICROGLOBULIN (ARE ALWAYS PRESENT).
• OTHERS INCLUDE- CERULOPLASMIN, HAPTOGLOBINS, ZN ALPHA 2
GLYCOPROTEIN.

14. • GP B- THESE ARE SPECIFIC PROTEINS SYNTHESISED BY TEAR GLANDS
KNOWN AS RAPID MIGRATING PROTEINS.
• 3 MAIN PROTEINS ARE- LYSOZYME, LACTOFERRIN & IGA
• ELECTROPHORETIC SEPARATION
• ALBUMIN-
58.2% OF TOTAL PROTEINS IN BASIC TEARS &
20.2% OF TOTAL PROTEINS IN REFLEX
• TEAR SPECIFIC PROTEIN (PREALBUMIN)-
ACIDIC PROTEIN, CONSTITUTES MOST ALB CONTENT IN TEARS, IT
INCRESES IN REFLEX TEARING, WHEREAS TOTAL ALB DECREASES IN REFLEX
TEARING
FUNCTION- AIDS OILY MEIBOMIAN SECRETIONS IN STABILIZING THIN
TEAR FILM.

15. • IGA
• IG A IS THE MOST PROMINENT TEAR IG
• SECRETORY IG PRODUCED LOCALLY BY PLASMA CELLS
• IT DIFFERS FROM CIRCULATING IG, IN HAVING
ADDITIONAL SECRETORY PIECE.
• PROVIDES EFFECTIVE DEFENCE AGAINST EXTERNALLY
INVASIVE VIRAL OR BACTERIAL ANTIGENS.

16. •LYSOZYME:-
IT’S A PROTEOLYTIC ENZ.
ITS CONCENTRATION IS HIGHEST IN TEARS.
ITS BASIC PROT OF MOL WT 14000-25000
PROTECTIVE AGENT AGAINST BACTERIAL INFECTION.
IT FACILITATES SECRETORY IGA MEDIATED BACTERIOLYSIS.
IT IS ACTIVE ONLY AGAINST CERTAIN GRAM POSITIVE ORGANISMS.

17. • METABOLITES:-
• GLUCOSE:-
MIN AMT 3-10MG/ML
(1/10TH THE CONC IN
BLOOD)
• LACTATE:-
1-5 MMOL/LIT, HIGHER
THAN NORMAL BLOOD
LEVELS
• PYRUVATE:-
SAME AS THAT OF
BLOOD.
• UREA:-
0.004MG/100ML
• ELECTROLYTES
Na- 142mEq/L
Cl- 120-135 mEq/L
HCO3- 26mEq/L
Ca- 2.29mg/100ml

18. PHYSIOLOGY OF TEAR FILM
• NORMAL CAPACITY OF CONJUNCTIVAL SAC IS 20-30
MICROLITRES, WHEN VOL OF TEARS SECRETED EXCEEDS
THIS AMT, RESULTS IN TEARING.

19. NERVE SUPPLY
SENSORY
LACRIMAL NERVE
SECRETOMOTOR
SUPERIOR
SALIVATORY
NUCLEUS-
7
SYMPATHETIC
SYMPATHETIC
PLEXUS – CERVICAL –
AROUND CAROTID
ARTERY

20. SYMPATHETIC
• POST GANGLIONIC FIBRES - FROM SUPERIOR CERVICAL
SYMPATHETIC GANGLION
• TRAVEL IN PLEXUS OF NERVES AROUND ICA-
• JOIN DEEP PETROSAL NERVE

22. • SECRETOMOTOR IE PARASYMPATHETHIC-
• SUPERIOR SALIVARY NUCLEUS
• SPHENOPALATINE GANGLION :
• FUNCTIONALLY – FACIAL NERVE, TOPOGRAPHICALLY – MAXILLARY
NERVE
• LARGEST PARASYMPATHETIC GANGLION

23. TEAR FILM DYNAMICS…..
THE MAIN ROLE OF LACRIMAL
APPARATUS IS TO ESTABLISH &
MAINTAIN A CONTINOUS TEAR
FILM OVER PREOCULAR SURFACE…

24. • DYNAMICS……- 8 CARDINAL HEADINGS
SECRETION OF TEARS.
FORMATION OF TEAR FILM.
RETENTION & REDISTRIBUTION OF TEAR FILM.
DISPLACEMENT PHENOMENON.
EVAPORATION FROM TEAR FILM
DRYING & BREAK UP OF TEAR FILM
DYNAMIC EVENTS DURING BLINKING
ELIMINATION OF TEARS….

25. 1. SECRETION OF TEARS….
• CONTINOUSLY SECRETED THROUGHOUT THE DAY
• BASAL SEC- ACCESSORY GLANDS & REFLEX- MAIN LAC GLANDS
• HYPERLAC D/T IRRITATIVE SENSATION FROM CORNEA & CONJUNCTIVA
• AFF-5TH NERVE, EFF- PARASYMPATHETIC SECRETOMOTOR FIBERS
• RATE-1.2MICROLT/MIN, VOL-7MIRCOLT, TURNOVER RATE-5-7MIN.
• NEWBORN DON’T PRODUCE EXCESS FLUID EVEN WHEN CRYING

26. 2. FORMATION OF PREOCULAR TEAR FILM….
• WETTABILITY OF A SURFACE- DETERMINED BY THE
TENDENCY OF LIQUIDS TO SPREAD ON IT.
• CORNEA IS A HYDROPHOBIC SURFACE
• CONJUNCTIVA FORMS A THIN LAYER OF MUCUS.
• ON THIS, AQUEOUS COMPONENT SPREADS
SPONTANEOUSLY.
• THEN FINALLY, SUPERFICIAL LIPID LAYER SPREADS
CONTRIBUTING TO ITS STABILITY & RETARDING
EVAPORATION BETWEEN BLINKS.

27. 3. RETENTION & REDISTRIBUTION OF TEAR FILM…
• TEAR FILM IS RETAINED AT UNIFORM THICKNESS OVER CORNEAL
SURFACE AGAINST GRAVITATIONAL FORCE.
• THE OUTER MOST LAYER OF CORNEAL EPITHELIUM, ALONG WITH
MUCOPOLYSACCHARIDES PLAY IMPORTANT ROLE IN RETAINING
FLUID ON CORNEAL SURFACE
• TEAR FILMS REMAINS STAGNANT, UNTIL BLINK OR EYE MOVEMENT
• REDISTRIBUTION OCCURS BY WAY OF BRINGING IN OF NEW TEAR
FILM- MARGINAL TEAR FILM STRIP

28. 4. DISPLACEMENT PHENONMENON…
• SURFACE OF CORNEA IS COVERED BY A FILM POSSESSING CERTAIN
STABILITY, COMPRESSIBILITY & ELASTICITY, WHICH IS UNAFFECTED BY
GRAVITY.
• DISPLACEMENT PHENOMENON (IE PARTICLES IN THE TEAR FILM MOVE
UP OR DOWN THE CORNEA AS AN INTEGRAL WHOLE, ALL PARTICLES
ON THE SURFACE INCLUDING THOSE LYING FAR AWAY FROM MARGIN
OF THE LID) IS POSSIBLE DUE TO THIN MONOMOLECULAR LAYER ON
THE SURFACE OF CORNEA.

29. 5. EVAPORATION FROM TEAR FILM…
• RETARDATION OF EVAPORATION OF WATER
IS BECAUSE OF LIPID LAYER MADE OF CHOLESTEROL
ESTERS & WAX
• EVAPORATION IS ABOUT 10% OF PRODUCTION RATE, WHICH
ACCOUNTS TO ABT 0.12MICROLT/MIN ( TEAR PRODUCTION
RATE IS 1.2 MICROLT/MIN)

30. 6. DRYING AND BREAK UP OF TEAR FILM
• TEAR FILM BREAK UP…
• PRECORNEAL TEAR FILM HAS A SHORT LIVED STABILITY.
• IF BLINKING IS PREVENTED FOR 15-40 SEC, TEAR FILM RUPTURES & DRY SPOTS APPEAR
ON CORNEA
• HOLLY & LEMPS MECHANISM OF TEAR FILM BREAK UP..
1. 1ST – FILM THINS UNIFORMLY BY EVAPORATION
2. AFT A CRITICAL THICKNESS, LIPID MOLECULES BEGIN TO BE ATTRACTED BY MUCIN
LAYER.
3. WHEN MUCIN LAYER ON EPITHELIUM IS SUFFICIENTLY CONTAMINATED BY LIPID
MIGRATING DOWN FROM TOP SURFACE OF THE FILM, MUCIN BECOMES HYDROPHOBIC
& TEAR FILM RUPTURES
4. BLINKING CAN REPAIR THE RUPTURE BY RESTORING THICK AQUEOUS LAYER.
5. DRY SPOT IS LOCALISED NON-WETTING, MORE ON TEMPORAL QUADRANT THAN

31. .

32. 7. DYNAMIC EVENTS DURING BLINKING…
• ACC. TO HOLLY..
• AS UPPER LID MOVES DOWNWARDS, SUPERFICIAL LAYER IS
COMPRESSED
• LIPID CONTAMINATED MUCUS IS ROLLED UP IN A THREAD LIKE
SHAPE & DRAGGED INTO LOWER FORNIX
• WHEN EYE OPENS, AT FIRST LIPID SPREADS IN FORM OF
MONOLAYER AGAINST THE UPPERLID, SPREADING OF EXCESS
LIPID FOLLOWS & MULTIMOLECULAR LAYER IS FORMED.
• SPREADING LIPID DRAGS SOME AQUEOUS TEARS WITH IT &
THICKENS THE FILM

33. • ELIMINATION OF TEARS….
DRAINAGE OF LACRIMAL FLUID FROM LACUS
LACRIMALIS INTO NASO LACRIMAL DUCT
Lacrimal fluid flows over the
preocular surface, reaches
marginal tear strip along
ciliary margin of each eye &
colllects as lacus lacrimalis
in inner canthus..From here
into lac passage into nasal
cavity

34. LACRIMAL PUMP MECHANISM…
CONSTITUTED BY FIBRES OF PRESEPTAL PORTION OF
ORBICULARIS WHICH ARISES FROM LAC FASCIA &
POSTERIOR LAC CREST( HORNER’S MUSCLE)
ON EYELID CLOSING 3 EVENTS OCCUR
CONCOMITANTLY
1.Contraction of pretarsal fibres of
orbicularis, compresses ampulla &
shortens canaliculi- this movement
propels tear fluid present in Ampulla
& horizontal part of canaliculi towards
lacrimal sac.

35. 2. CONTRACTION OF PRESEPTAL FIBRES
OF ORBICULARIS PULLS LAC FASCIA &
LATERAL WALL OF LAC SAC LATERALLY,
HENCE OPENING NORMALLY CLOSED LAC
SAC- PRODUCES RELATIVE NEGATIVE
PRESSURE & DRAWS TEARS FROM
CANALICULI INTO SAC.
3. WITH THE INCREASING TENSION ON THE
LACRIMAL FASCIA (WHICH OPENS THE SAC),
INFERIOR PORTION CLOSES MORE TIGHTLY,
PREVENTING ASPIRATION OF AIR FROM
NOSE.

37. WHEN EYELIDS OPEN, TONE OF ORBICULARIS
MUSCLE DECREASES & FOLLOWING EVENTS
OCCUR CONCOMITANTLY…
1. RELAXATION OF PRETARSAL FIBERS OF
ORBICULARIS–
CANULICULI TO EXPAND & REOPEN.
EXPANSION OF
CANALICULI & AMPULLA DRAWS IN LAC
FLUID
THROUGH PUNCTI FROM LAC LAKE.
2. RELAXATION OF PORTION OF PRESEPTAL
FIBRES
(HORNERS MUSCLE) ALLOWS LAC SAC TO
COLLAPSE.
THIS COLLAPSE OF LAC SAC EXPELS FLUID
DOWNWARDS INTO NASOLACRIMAL DUCT.

39. 8. DRAINAGE OF LACRIMAL FLUID FROM NASO LACRIMAL
DUCT INTO NASAL CAVITY…
• ONCE FLUID ENTERS UPPER END OF NLD, INFLUENCE OF
EYELID MOVEMENTS ON ITS FURTHER DOWNWARD FLOW
ENDS.
• FACTORS WHICH INFLUENCE FLOW OF TEARS ALONG
NLD ARE-
1. GRAVITY IN DOWNWARD MOVEMENT.
2. AIR CURRENT MOVEMENT WITHIN THE NOSE- INDUCE
NEGATIVE PR WITHIN NLD & THUS DRAWS FLUID
DOWN THE POTENTIAL LUMEN OF DUCT INTO NOSE.

40. 3. HASNER’S VALVE PRESENT AT LOWER END
OF NLD REMAINS OPEN AS LONG AS
PRESSURE WITHIN THE NOSE IS LESS THAN
NLD & THUS ALLOWS TEARS TO FLOW FROM
NLD INTO NOSE.
WHEN INTRANASAL PRESSURE
INCREASES( EG: BLOWING OF NOSE)
HASNERS VALVE CLOSES, HENCE
PREVENTING REFLUX UPWARD
FROM NOSE, TEARS PASS POSTERIORLY
WITH NASAL MUCUS SECRETIONS.

41. TEAR FUNCTION TESTS
• TEAR BREAK UP TIME
• SCHIRMER TEST
• PHENOL RED THREAD
TEST
• TEAR LYSOZYME ASSAY
• TEAR LACTOFERRIN
ASSAY
• FLOURESENE TEST
• ROSE BENGAL STAINING
 CONJ. SCRAPPING
 PH
 TEAR EVAPORATION
RATE
 FLUROPHOTOMETRY
• TEAR OSMOLARITY

42. 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
TEAR FILM TESTS

43. • 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.

44. DRY SPOT

45. 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 STANDARD.
-GIVES THE VALUE FOR BASIC AND REFLEX SECRETION OF TEARS
*BASAL SECRETION TEST– CONJUNCTIVA IS ANAESTHETIZED
BEFORE PERFORMING THE TEST

46. -TYPE-II
- TO KNOW REFLEX 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

47. • TYPE III-
-TO KNOW THE REFLEX SECRETION
-ASK THE PT. TO LOOK DIRECTLY IN SUN
-NO DIAGNOSTIC VALUE, AND IS POTENTIALLY DANGEROUS.

48. • 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.

49. 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.

50. 4. TEAR LYSOZYME ASSAY
- MOST OFTEN TEAR LYSOZYME DECREASES BEFORE DRY EYES ARE
CLINICALLY EVIDENT. SO IT IS OF GREAT DIAGNOSTIC &PROGNOSTIC VALUE.
NOT POPULAR
5.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 CLOSELY RESEMBLES TO TEAR PRODUCTION.
TEAR LACTOFERRIN DECREASED IN SJOGREN SYNFROME.

51. 6.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.
7 TEAR OSMOLARITY -NORMAL VALUE 3.02±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

52. 8.CONJUNCTIVAL SCRAPING -
STAINS WITH GIEMSA STAIN -IN DRY EYES IT SHOWS NUMEROUS
GOBLET CELLS WITH PINK CYTOPLASM AND NUCLEUS ON ONE SIDE
OF CELL.
9.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.

53.  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.

54. 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

55. 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
KERATINIZATION
STAGE 4: MODERATE
KERATINISATION
STAGE 5: ADVANCED
KERATINISATION

56. - 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.

57. 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.

58. 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
STAINING PROCEDURE

59. 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
• .

60. - 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

61. 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.

62. • 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