Lacrimal

Question 1

Lacrimal gland

Answer 1

Where tears are produced

Question 2

Lacrimal sac

Answer 2

Where tears drain after they have done their job

Question 3

Lipid layer

Answer 3

• Outer, thinnest layer
• oily layer secreted by MG
• prevents tear evaporation
• acts as lubricant to smoothen eyelid movements

Question 4

Aqueous Layer

Answer 4

• Thickest, main functioning layer
• secreted by lacrimal glands
• supplies oxygen to corneal epithelium
• has antibacterial enzymes that help prevent infection on corneal surf
• Smoothens corneal surface
• helps wash away debris

Question 5

Mucin Layer

Answer 5

• Innermost layer of TF
• mucous secreted by conj goblet cells
• converts corneal surface from hydrophobic to hydrophilic

Question 6

Mechanism of Lacrimal drainage

Answer 6

• Negative pressure in the lower and upper canaliculi which sucks in tears from TF
• closure of the eye causes lacrimal sac to dilate which sucks in tears from canaliculi to sac
• eye opens again, lacrimal sac collapses and pushes fluid down nasolacrimal duct, at the same time canaliculi have negative pressure
• cycle repeats

Question 7

Hyperlacrimation

Answer 7

Excessive tear production

Question 8

Impaired drainage

Answer 8

Tears unable to drain the way they should

Question 9

Common cause of reflex hyperlacrimation

Answer 9

Dry eye

Question 10

Dry eye symptoms

Answer 10

• watering
• ocular irritation/burning
• FB sensation
• photophobia
• symptoms worse when reading, watching tv etc (due to a reduced blink reflex)
• px’s rarely will complain of eyes actually feeling dry

Question 11

Dry eye signs

Answer 11

• small TM
• mucous strands in conj
• corneal punctate staining with fluorescein (caused by micro abrasions on the corneal surface due to lack of wetting on surface)
• shorter TBUT
• corneal filamnets (severe cases)

Question 12

Dry eye investigations

Answer 12

• tear meniscus height
• TBUT
• schirmer’s test

Question 13

Tear meniscus height method

Answer 13

• stain tears with fluorescein
• using blue light
• measure the height of the TF from the lower lid margin
• normal height = 1-1.5mm
• px with dry eye - very thin tear meniscus

Question 14

Tear break-up time method

Answer 14

• drop of fluorescein is instilled in px’s eye
• ask px to blink a few times and then stop blinking
• start timer
• observe for development of first dry spot on cornea (indicates when TF breaks up)
• time taken for first dry spot to appear is recorded

Question 15

Schirmer’s test method

Answer 15

• gently dye the eye
• place filter paper folded at the 5mm mark to the lower fornix
• measure wetting of paper after 5 mins
• normal = 15mm or more of wetting
• borderline DE - 5-10mm of wetting
• significnst DE - <5mm of wetting

Question 16

Dry eye advice to px

Answer 16

• advice - chronic condition, one has to learn to manage it rather than cure
• avoid areas of low humidity, warm room with too much heating, humidifiers

Question 17

Dry eye tear substitutes

Answer 17

• hypromellose
• polyvinyl alcohol
• carbomer gels
• sodium hyaluronate based
• petrolatum based ointments
• acetylcysteine eye drops (more so in hospital)
• ciclosporin eye drops ( more so in hospital)

Question 18

Dry eye - punctal occlusion

Answer 18

• silicone plug to block upper and lower lacrimal puncta
• stops drainage of whatever little tears are produced in DE px’s
• allows tears to remain on ocular surface

Question 19

Obstruction to drainage reasons for reduced tear drainage

Answer 19

• canalicular obstruction/inflammation
• nasolacrimal duct blockage
• lacrimal sac tumours

Question 20

Physiological reasons for reduced tear drainage

Answer 20

• eyelid malpositions (ectropion/entropion)
• lacrimal pump failure (orbicularis oculi weakness)
• nasal pathology with normal lacrimal pathway

Question 21

Evaluating a watery eye - examination

Answer 21

• eyelid position
• dynamic eyelid closure (what happens to eyes when px actively closes them)
• evaluate puncta
• lacrimal sac
• tear meniscus
• TBUT

Question 22

Eyelid laxity - lid distraction test

Answer 22

• if eyelid pulled >8mm from cornea - horizontal lid laxity

Question 23

Eyelid laxity - snap back test

Answer 23

• pull lower lid down with finger at centre of orbital rim
• release and observe return of eye
• normal - quickly snaps back
• mild lid laxity - slowly snaps back
• moderate lid laxity - returns with blink
• severe lid laxity - incomplete return, does not go back to normal position easily

Question 24

Examining puncta

Answer 24

• normal - puncta directed posteriorly in contact with globe
• look for punctal eversion, stenosis, absence, FB
• canaliculitis - inflammation of lacrimal puncta with discharge

Question 25

Fluorescein dye disappearance test

Answer 25

• drop of fluorescein instilled in both eyes
• carry on H&S
• after 5 mins, fluorescein should start disappearing from eye as it drains into nasolacrimal duct

Question 26

Blocked lacrimal drainage pathway symptoms

Answer 26

• watering of eye
• both indoors and outdoors (constant)
• worse outdoors as there is more reflex epiphora in those cases
• tears tend to run down inner corner of eye as this is where tear ducts are
• tears don’t drain through tear ducts and drain medially
• lower lid skin irritation as tears are salty and irritate skin surface causing eczema type changes on skin

Question 27

Blocked lacrimal drainage pathway upon examination

Answer 27

• high tear meniscus
• delayed FDDT
• lid position abnormalities ruled out
• examining lacrimal puncta (stenosis, occlusion)

Question 28

Lacrimal sac syringing method

Answer 28

• inject saline into lower canaliculi
• normal nasolacrimal system - saline drains through lacrimal sac and nasolacrimal duct into the nose and px feels salt water coming down throat and into nose

Question 29

Dacryocystogram

Answer 29

• special dye injected into lacrimal system
• x-rays of face are taken to check drainage