Lecture on Composition of Tear Film & Dry Eye For 4th Year MBBS Undergraduate Students By Prof. Dr. Hussain Ahmad Khaqan

1. Composition of Tear Film
& Dry Eye
Prof. Dr. Hussain Ahmad Khaqan
 MD
 FRCS(Glasgow)
 FCPS(Ophth.)
 FCPS(Vitreo Retina)
 MHPE (KMU)
 CICO(UK)
 CMT(UOL)
 Fellowship in Medical Retina (LMU, Munich)
 Fellowship in Vitreo Retinal Surgery (LMU, Munich)
 Consultant Ophthalmologist & Retinal Surgeon
Professor of Ophthalmology
Lahore General Hospital, Lahore
Ameer Ud Din Medical College, Lahore
Post Graduate Medical Institute, Lahore
Shaukat Khanum Memorial Cancer Hospital & Research Centre ,Lahore

2. TRILAMINAR STRUCTURE
• Tear film is rather more complex. The layers blend
together, forming a muco-aqueous gradient on the
surface of the eye.

3. LAYERS OF TEAR FILM Continue..

4. PHOSPHOLIPID LAYER
• The aqueous layer is supported by a phospholipid
layer (secreted primarily by the meibomian glands)
that resists evaporative loss of aqueous and stabilizes
the tear film by increasing surface tension.

5. AQUEOUS LAYER Continue..
• The aqueous component (secreted by the lacrimal
gland and the accessory glands) consists primarily of
water, but also proteins such as epidermal growth
factor, lactoferrin, lysozyme, immunoglobulins and
cytokines.

6. MUCIN LAYER Continue..
• The mucin layer (secreted primarily by the goblet
cells) abuts the surface epithelium and provides a
smooth hydrophilic surface that stabilizes the
aqueous against the otherwise hydrophobic
epithelium.

7. DRY EYE

8. DEFINITION
• “Dry eye is a multifactorial disease of the ocular
surface characterized by a loss of homeostasis of the
tear film and accompanied by ocular symptoms, in
which tear film instability and hyperosmolarity,
ocular surface inflammation and damage and
neurosensory abnormalities play etiological roles.”

9. SYMPTOMS
• Burning
• Ocular and conjunctival irritation
• Foreign body sensation
• Dryness
• Photophobia
• Ocular fatigue
• Redness
• Blurred vision

10. SIGNS
• Conjunctival injection
• Decreased tears meniscus
• Loss of corneal sheen
• Rapid tear film break-up
• Filamentary keratitis
• Sterile ulceration of the cornea
• Thinning and perforation of these ulcers

11. Figure : Punctate epithelial erosions stained with
fluorescein
Figure : Filamentary keratitis stained with
fluorescein
Figure : Appearance of black spots as tear film
breaks.
Figure : Conjunctival injection in a patient with dry
eye disease

12. CAUSES
• Sjogren’s syndrome
• Lacrimal gland deficiencies
• Lacrimal gland duct obstruction
• Reflex hypersecretion
• Systemic drugs
• Intrinsic (direct effect on evaporation)
• Extrinsic (indirect effect via changes to ocular
surface)

13. WORK UP
• Tear film break up time<10s
• Schirmer test <5mm over 5min (without topical anaesthetic)
• Staining: Fluorescein, Rose Bengal stain and lissamine green
• Hyperosmolarity
• Inflammatory biomarkers, such as IL-1, IL-17, MMP-9,
interferon-γ(IFN-γ) and human leukocyte antigen–antigen D–
related (HLA-DR).
• Fluorophotometry for decreased protein content
• Lysozyme levels, ocular ferning, impression cytology and
lactoferrin assays.
• Noninvasive imaging of the tear film: meniscometry, lipid
layer interferometry, high speed videography, optical
coherence tomography and confocal microscopy.

14. TEAR SUBSTITUTES
Commonly used artificial tears and lubricants (selected)
Viscosity Frequency Preserved examples Preservative Free (PF)
examples
Low
Hypromellose/ polyvinyl
alcohol
q 4h-q 1/2h Hypromellose
Hypotears®
Liquifilm® (PF)
Refresh®
Medium
Carbomer/cellulose/guar gum
1-6x/d viscotears®
GelTears®
Systane®
celluvisc® (0.5%/1%) viscotears
PF®
Systane Ultra
High
Paraffins
1-4x/d Lacri-Lube®
Vit-A-Pos®
Simple eye ointment

15. TREATMENT
Treatment according to severity level
Level 1 Level 2 Level 3 Level 4
If level 1 treatment inadequate
add:
If level 2 treatment inadequate
add:
If level 3 treatment inadequate
add:
Educational and
environmental/dietary
Modifications
Topical anti inflammatory Autologous serum Systemic anti inflammatory
drugs
Elimination of offending
systemic medications
Tetracyclines (for
meibomianitis or rosacea)
Contact lens Surgery (lid surgery
tarsorrhaphy; salivary gland
transposition, mucous
membrane/ Amniotic
membrane
Artificial tear substitutes,
gels/ointments
Punctal plugs Permanent punctal occlusion
Lid hygiene Secretagogues