Dry eye, also known as keratoconjunctivitis sicca, is a condition caused by either a deficiency in tear production or abnormalities in the tear film that lead to increased tear evaporation. There are two main types - aqueous deficiency dry eye and evaporative dry eye. Common tests used to diagnose dry eye include tear film break-up time (TBUT), Schirmer test to measure tear production, and rose Bengal staining to detect damage to the ocular surface. Signs and symptoms include irritation, dryness, redness, and punctate erosions seen on fluorescein staining of the cornea. Treatment focuses on managing the underlying cause, supplementing tears, and preventing further tear film evaporation

1. DRY EYE ( INTRODUCTION , INVESTIGATIONS & BASIC )
DR. REENA
SCEH, LAHAN
CORNEA CONSULTANT

2. TEAR FILM : Structure of tear film
• Wolff was the first to describe the detailed structure of the fluid covering the
cornea & called it precorneal film.
• It consist of three layers, which from posterior to anterior are mucus layer,
aqueous layer & lipid or oily layer
• Normal thickness of tear film will be 7 to 9 um

3. Components & structure

4. Normally there are 3 layers of tear lilm
• 1. Mucus layer. It is the innermost & about 0.2 mm thick stratum of the tear film. It
consists of mucin secreting conjunctival goblet cells & glands of
Manz. It converts the hydrophobic corneal surface into hydrophilic one.

5. • 2. Aqueous layer. The bulk of tear film (7.0 mm) is formed by this intermediate
layer which consists of tears secreted by the main & accessory lacrimal glands.
The tears mainly comprise of water & small quantities of solutes such as sodium
chloride, sugar, urea & proteins. Therefore, it is alkaline & salty in taste. It also
contains antibacterial substances like lysozyme, betalysin & lactoferrin.

6. • 3. Lipid or oily layer.
• This is the outermost & thinnest (0.1 mm) layer of tear film formed at air-tear
interface from the secretions of meibomian, zeis & moll glands.
• This layer prevents the overflow of tears, retards their evaporation & lubricates
the eyelids as they slide over the surface of the globe

7. Function of the tear film
• 1. Keeps moist the cornea & conjunctiva.
• 2. Provides oxygen to the corneal epithelium.
• 3. Washes away debris & irritants.
• 4. Prevents infection due to presence of anti-bacterial substances.
• 5. Facilitates movements of the lids over the globe

8. Secretion of the tear ( basic mechanism )
• Tears are continuously secreted throughout the day by accessory (basal secretion)
& main (reflex secretion) lacrimal glands.
• Reflex secretion is in response to sensations from the cornea & conjunctiva.
• Hyperlacrimation occurs due to irritative sensations from the cornea & conjunctiva.
• Afferent pathway of this secretion is formed by fifth nerve & efferent by
parasympathetic (secretomotor) supply of lacrimal gland .

9. Elimination of tear & lacrimal pump mechanism ?
• About 70% tears is drained via inferior canaliculus & 30% via the superior
canaliculus by an active lacrimal pump mechanism….
• When the eyelids close with each blink there occurs:
• • Contraction of pretarsal orbicularis oculi which compresses the ampulla &
shortens the canaliculi. This movement expel the tear fluid present in the
ampulla & horizontal part of canaliculi towards the lacrimal sac.

10. lacrimal pump is for tear elimination & it occure with each blink
response

11. • • Contraction of preseptal fibers of orbicularis distends the lacrimal sac &
creates therein a negative pressure which draws the tear fluid from canaliculi
into the lacrimal sac .
Similarly other mechanism of lacrimal pump is due to relaxation of preseptal &
pretarsal orbicularis .( when eyelids open )

12. • When the eyelids open following events occur:
• • Relaxation of pretarsal orbicularis allows the canaliculi & ampulla to expand &
reopen, and to draw the tear fluid from the lacus lacrimalis and marginal tear
strips.
• • Relaxation of preseptal fibres (Horner’s muscle) results in collapse of sac, as a
consequence a positive pressure is created which forces the tears down the
nasolacrimal duct (NLD) into the nose. Gravity also helps in downward flow of tears
along the NLD.

13. DRY EYE (OSD) : The dry eye is not a disease entity, but a symptom complex
occurring as a sequelae to deficiency or abnormalities of the tear film.
• According to International Dry Eye Workshop report (DEWS report 2007), the
causes of dry eye can be classified as :
• I. Aqueous deficiency dry eye
• II. Evaporative dry eye

14. Classification (table DEWS)

15. Etiology & causes of dry eyes
• I. Aqueous deficiency dry eye
• It is also known as keratoconjunctivitis sicca (KCS). Its causes include:
• a. Sjogren’s syndrome (Primary keratoconjunctivitis sicca).
• b. Non-Sjogren’s keratoconjunctivitis sicca. Causes are :
• 1. Primary age-related hyposecretion is the most common cause.
• 2. Lacrimal gland deficiencies as seen in congenital absence of gland , infiltrations of
lacrimal gland by e.g., tumours, post-radiation fibrosis of lacrimal gland & surgical
removal of gland .

16. OTHER CAUSES OF AQUEOUS DEFICINECY DRY EYES
• 3. Lacrimal gland duct obstruction as seen in old trachoma, chemical burns &
Stevens-Johnson syndrome. (SJS)
• 4. Reflex hyposecretion (neurogenic causes) as seen in Parkinson disease, reflex
sensory block, 7th cranial nerve damage, reduced corneal sensations after
refractive surgery & corneal lens wear.

17. II. Evaporative dry eye : caused by the conditions which decrease
tear film stability & thus increase evaporation.
• 1. Meibomian gland dysfunction as seen in chronic posterior blepharitis, rosacea,
& congenital absence of meibomian glands.
• 2. Lagophthalmos as seen in facial nerve palsy, severe proptosis & symblepharon
• 3. Defective blinking such as low blink rate as seen in prolonged computer users .
• 4. Vitamin A deficiency

18. Clinical features Symptoms suggestive of dry eye
• Irritation, foreign body (sandy) sensation, feeling of dryness, itching, nonspecific
ocular discomfort & chronically sore eyes not responding to a variety of eye drops .

19. Signs of dry eyes
• Tear film signs. :
• It may show presence of stingy mucous .
• Marginal tear strip is reduced or absent (normal height is 1 mm).
• Froth in the tears along the lid margin is a sign of meibomian gland dysfunction
(MGD)

20. • Conjunctival signs.
• It becomes lustureless, mildly congested, conjunctival xerosis & keratinization m ay
occur. Rose Bengal or Lisamin green staining may be positive .
• Corneal signs.
• It may show punctate epithelial erosions /spk , filaments & mucus plaques.
• Cornea may loose lusture.
• Vital stains, fluorescein, Rose Bengal or Lisamin green may diagnose this lesion .

21. • Signs of causative disease such as posterior blepharitis, conjunctival scarring
diseases (trachoma, Stevens-Johnson syndrome & chemical burns etc. ) &
lagophthalmos may be present .

22. TEAR FILM TEST
• These include tear film break-up time (BUT), Schirmer-I test, vital staining with Rose
Bengal, tear levels of lysozyme & lactoferrin, tear osmolarity & conjunctival
impression cytology.
• Out of these TFBUT, Schirmer-I test & Rose Bengal staining are important to
diagnose dry eyes ( OSD )

23. DIAGNOSTIC TESTS
The tests measure the following parameters:
• Stability of tear film as related to its break-up time (BUT)
• Tear production (schirmer, fluorescein clearance and tear osmolarity)
• Ocular surface disease (corneal stains)

24. diagnosis : clinical evaluation .

25. Tests For Tear Hyposecretions
Tear Film Break-up Time (TBUT)
• It is done to assess the stability of the precorneal tear film.
• It is abnormal in aqueous tear deficiency and Meibomian gland disorder.
Procedure:
• Fluorescein strip is moistened with non- preserved saline is instilled into the lower
fornix.
• At the slit lamp with a broad beam using cobalt blue filter tear film is examined
• After interval of time black spots or line indicating dry spots appear in the tear film.
• BUT is the time between the last blink and the appearance of the first randomly
appearance distributed dry spot.
• Normal value >10sec, marginal 5-10sec, severe <5sec

27. NON- INVASIVE TEAR BREAK-UPTIME
• Non- Invasive Technique
• Can Be Done By Using Placido Disc, Keratometer, Auto-refractometer, tearscope
Or Keratograph 5m.
• Procedure Same As TBUT
• Normal >20sec
• Marginal 10-20sec
• Abnormal <10sec

28. SCHIRMER TEST
SCHIRMER’S I TEST WITHOUT ANESTHESIA:
• The person is seated comfortably at rest
• The filter paper is folded at 5mm distance from one end and placed over the
lower lid margin taking care not to touch the cornea during the procedure
• Place it at the junction of medial 2/3rd and lateral 1/3rd of the lower lid for a
period of 5 minutes
• The wetting of the strip is recorded at the end of 5 minutes

29. type 2 Schirmer ….

30. SCHIRMER’S I TEST WITH ANESTHESIA
• Done 15 minutes after doing the test without anesthesia
• Proparacaine hydrochloride 0.5% is instilled into the lower conjunctival cul-de-
sac
• 1 drop, is instilled 1 minute apart for 2 times
• The excess anesthetic solution in the lower conjunctival cul-de-sac is gently
wiped off with a cotton tipped applicator 1 minute after instillation of the last
drop of proparacaine
• Filter paper is placed in the same manner as done for the procedure without
anesthesia for 5 minutes
• The wetting of the strip is recorded at the end of 5 minutes

31. • Without anesthesia: the basal tear secretion and the function of the main
lacrimal gland whose secretory activity is stimulated by the irritating nature of
the filter paper.
• After topical anesthesia: the function of the basal lacrimal secretion
• Normal schirmer test i values >10 mm in 2 minutes,
• Abnormal values without anesthesia: <10mm in 5 minutes
• With anesthesia: 10mm in 5min

34. TEAR MINISCUS HEIGHT
• Measures the tear meniscus formed on the amount of tears
resting at the
• junction of the bulbar conjunctiva and the lower eyelidmargin.
• Can be done with or without staining
• Thin Optic Section
• Primary Gaze
• Middle Of Lower Lid Margin
• Normal Blinking
• Normal meniscus height is 0.2–0.5 mm
• A value of <0.2mm suggests a tear insufficiency

35. PHENOL REDTHREAD TEST
A soft thread is touched to the lid and the results are obtained in 15 seconds per
eye
PROCEDURE:
• Remove the thread by peeling the film
• Bend 3mm end of the thread
• Pull lower eyelid slightly down & place 3mm folded thread on palpebral
conjunctival junction
• Patient is asked to look straight and blink normally
• After 15 second the thread is gently removed with an upward motion
• The entire length of the red portion of the thread is measured in mm from the
very tip regardless of the fold
• True dryness <10 mm wetting, borderline 10 to 20 mm wetting , and >20 mm

36. ROSEBENGALSTAINING
• Rose bengal is a fluorescein derivative
• It was thought to stain only devitalized epithelial cells but it also stains healthy
epithelial cells when they are not protected by a healthy layer of mucin
• It has the unique property of evaluating the protective status of the preocular tearfilm.
• It also stains dead or degenerating cells, lipid-contaminated mucous strands, and
corneal epithelial filaments
• Rose Bengal causes significant ocular discomfort
• It can be difficult differentiating its red stain in patients with inflamed red eyes
• The interpretation of rose Bengal staining in dry eyes is based on two factors, intensity
and location.
• A grading scale that evaluates the intensity based on a scale of 0 to 3 in three areas:
nasal conjunctiva, temporal conjunctiva and cornea, with a maximum possible score of 9

37. • May help to differentiate between ATD and lipid tear deficiency (LTD) by
studying the distribution of stain in the non-exposure zone
• Preferential staining has been observed in non exposure zones in the LTD
• In ATD the staining is seen in the exposed interpalpebral areas.

39. Rose Bengal stain

40. HOME WORK
1. What is dry eye ? Classification of dry eyes ?
2. What is tear film ? What are layers of tear film ?
3. What are the function of tear film ?
4. What are the signs & symptoms of dry eye ?
5. What are normal investigation done to diagnose dry eye syndrome ?
6. What are the causes of of dry eye ?
7. What is Schirmer test 1 & 2 ? What is procedure ?
8. What in normal tear meniscus ? What is the significane of that ?
9. Explain in brief rose Bengal test to diagnose dry eye ?

41. ThankYou