Fisiologi Tear Film

7/26/2019 Fisiologi Tear Film

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1.2.1 Fisiologi Tear Film

Tear film normal diperlukan untuk mempertahankan fungsi permukaan okuler.

Perubahan patologis yang terlihat pada dry eye disease mempengaruhi semua

komponen tear film,mengubah bagian permukaan okuler yang awalnya bersifat

ocular surface supportive menjadi pro - inflamatory(Khurana, 200!.

"olume terbesar air mata dihasilkan oleh kelenjar lakrimalis yang terletak di

fossa glandula la#rimalis yang terletak di kuadran temporal atas orbita. Kelenjar yang

berbentuk kenari ini dibagi oleh kornu lateral aponeurosis le$ator menjadi lobus orbita

yang lebih besar dan lobus palpebra yang lebih ke#il, masing%masing dengan sistem

duktulus yang bermuara ke forniks temporal superior (Khurana, 200!.

Persarafan kelenjar utama datang dari nu#leus la#rimalis di pons melalui ner$us

intermedius dan menempuh suatu jaras rumit #abang ma&illaris ner$us trigeminus.

Kelenjar lakrimal assesorius, walaupun hanya sepersepuluh dari massa kelenjar utama,

mempunyai peranan penting. 'truktur kelenjar Krause dan olfring identik dengan

kelenjar utama, namun tidak memiliki du#tus. Kelenjar%kelenjar ini terletak di dalam

konjungti$a, terutama di forniks superior. 'el%sel goblet uniseluler, yang juga tersebar di

konjungti$a, mensekresi glikoprotein dalam bentuk musin. )odifikasi kelenjar sebasea

meibom dan *eis ditepian palpebra memberi lipid pada air mata. Kelenjar )oll adalah

modifikasi kelenjar keringat yang ikut membentuk tear film. (Khurana, 200!.

+ambar 2. Produksi -ear film

(http//www.ad$o#urenf2.org/li$ingwithnf2ailments1#aredryeye.php !
http://www.advocurenf2.org/livingwithnf2_ailments+care_dryeye.phphttp://www.advocurenf2.org/livingwithnf2_ailments+care_dryeye.php


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'ekresi kelenjar lakrimal dipi#u oleh emosi atau iritasi fisik dan menyebabkan air

mata mengalir melimpah melewati tepian palpebra (epifora!. Kelenjar lakrimal

assesorius dikenal sebagai pensekresi dasar. 'ekret yang dihasilkan normalnya

#ukup untuk memelihara kesehatan kornea. ilangnya sel goblet, berakibat

mengeringnya korena meskipun banyak airmata dari kelenjar lakrimal.(Khurana, 200!.

1.2.2 Fungsi Tear Film.

3ir mata membentuk lapisan tipis setebal %40 5m yang menutup epitel kornea

dankonjungti$a(Khurana, 200!.

6ungsi lapisan ultra tipis ini adalah

4! )embuat kornea menjadi permukaan optik yang li#in denganmeniadakan ketidakteraturan minimal di permukaan epitel. -ear film adalah

komponen penting dari the eyes optical system. -ear film dan permukaan

anterior kornea memiliki mekanisme untuk memfokuskan refraksi sekitar

07. 8ahkan sebuah perubahan ke#il pada kestabilan dan $olume tear film

akan sangatmempengaruhi kualitas penglihatan (khususnya pada sensiti$itas

pada kontras!. Tearbreak up menyebabkan aberasi optik yang akan

menurunkan kualitas fokus gambaranyang didapatkan retina. 9leh karena itu,

ketidakteraturan pada tear film preo#ular merupakan penyebab gejala $isual

fatiguedan fotofobia.2! )embasahi dan melindungi permukaan epitel kornea dan konjungti$a yang

lembut. Pergerakan kelopak mata dapat menimbulkan gaya : 4;0 dyne/#m

yang mempengaruhi tear film. ", alergen dan iritan. Tear filmharus memiliki stabilitas untuk

menghadapi paparan lingkungan tersebut. Komponen tear film yang


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berfungsi untuk perlindungan adalah ?g3, laktoferin, liso*im dan en*im

peroksidase yang dapat melawan infeksi bakteri maupun $irus.


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o ?nfeksi atau kerusakan berulang pada kelenjar ini (seperti hordeolum,

kala*ion serta blefaritis! akan menyebabkan gangguan lapisan lemak

sehingga terjadi Clipid deficiency dry eyeC akibat penguapan berlebihan.o 6ungsi

)enghambat penguapan lapisan air mata. )eningkatkan tekanan permukaan.

)elubrikasi kelopak mata.


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Eat anti bakteri la#toferin, lyso*yme, betalysin.

)emberikan permukaan optis yg halus.

)embersihkan debris.

o )ekanisme terbentuknya airmata

Pada saat mengedip dan saat mata terbuka di antara kedipan. Pada saat mata terbuka, lapisan air mata (aAuous! akan berkurang

akibat e$aporasi serta aliran keluar melalui pungtum dan duktus

nasolakrimal.

3pabila mata mulai terasa kering dan terjadi Cdry spotC pada kornea,

mata akan terasa perih, menimbulkan rangsangan pada saraf

sensoris dan terjadi refleks mengedip sehingga lapisan airmata

terbentuk lagi dan seterusnya.


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o


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non%liso*im lain, membentuk mekanisme pertahananpenting terhadap infeksi. Dn*im air

mata lain juga bisa berperan dalam diagnosis berbagaikondisi klinis tertentu, mis.,

he&oseaminidase untuk mendiagnosis penyakit -ay%'a#hs.("aughan, 200!

+ambar 2.44Komposisi air mata

(http//majiidsumardi.blogspot.#om/2044/44/air%mata.html !

Clinical features

Symptoms suggestive of dry eye include irritation,

foreign body (sandy) sensation, feeling of dryness,

itching, non-specific ocular discomfort and

chronically sore eyes not responding to a variety of

drops instilled earlier.Signs of dry eye include: presence of stringy mucus

and particulate matter in the tear film, lustureless

ocular surface, conjunctival xerosis, reduced or absent

marginal tear strip and corneal changes in the form of

punctate epithelial erosions and filaments.

Tear film tests

These include tear film break-up time (!T), "chirmer-# test, vital staining $ith %ose engal, tear levels of

Fig. 15.3. &limination of tears by lacrimal pump mechanism.

lyso'yme and lactoferrin, tear osmolarity and
http://majiidsumardi.blogspot.com/2011/11/air-mata.htmlhttp://majiidsumardi.blogspot.com/2011/11/air-mata.html


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dr. prashant goyal

366 Comprehensive *+T**/0

conjunctival impression cytology. *ut of these !T,

"chirmer-# test and %ose engal staining are mostimportant and $hen any t$o of these are positive,

diagnosis of dry eye syndrome is confirmed.

1. Tear film break-up (BUT). #t is the interval bet$een

a complete blink and appearance of first randomly

distributed dry spot on the cornea. #t is noted after

instilling a drop of fluorescein and examining in a

cobalt-blue light of a slit-lamp. !T is an indicator of

ade1uacy of mucin component of tears. #ts normalvalues range from 23 to 43 seconds. 5alues less than

26 seconds imply an unstable tear film.

2.Schirmer-I test. #t measures total tear secretions. #t

is performed $ith the help of a 3 7 43 mm strip of

8hatman-92 filter paper $hich is folded 3 mm from

one end and kept in the lo$er fornix at the junction of

lateral one-third and medial t$o-thirds. The patient isasked to look up and not to blink or close the eyes

(ig. 23.9). fter 3 minutes $etting of the filter paper

strip from the bent end is measured. ;ormal values of

"chirmer-# test are more than 23 mm. 5alues of 3-26

mm are suggestive of moderate to mild

keratoconjunctivitis sicca (? pattern represents mild or

early cases $ith fine punctate stains in the


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interpalpebral area@ >? the moderate cases $ith

extensive staining@ and >? the severe cases $ith

confluent staining of conjunctiva and cornea.

Treatmentt present, there is no cure for dry eye. The follo$ing

treatment modalities have been tried $ith variable

results:

1.Supplementation with tear substitutes. rtificial

tears remains the mainstay in the treatment of dry

eye. These are available as drops, ointments and slo$release

inserts. ostly available artificial tear drops

contain either cellulose derivatives (e.g., 6.A3 to 6.BCmethyl cellulose and 6.4C hypromellose) or polyvinyl

alcohol (2.9C).

2. Topical cyclosporine (6.63C, 6.2C) is reported to

be very effective drug for dry eye in many recent

studies. #t helps by reducing the cell-mediated

inflammation of the lacrimal tissue.

3.ucolytics, such as 3 percent acetylcystine used9 times a day help by dispersing the mucus threads

and decreasing tear viscosity.

4. Topical retinoi!s have recently been reported to

be useful in reversing the cellular changes (s1uamous

metaplasia) occurring in the conjunctiva of dry eye

patients.

5."reser#ation of e$isting tears by re!ucing

e#aporation an! !ecreasing !rainage.

DEvaporation can be reducedby decreasing room

temperature, use of moist chambers and protective

glasses.

DPunctal occlusion to decrease drainage can be


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carried out by collagen implants, cynoacrylate

tissue adhesives, electrocauterisation, argon laser

occlusion and surgical occlusion to decrease the

drainage of tears in patients $ith very severedry eye. (kurana)

acrimal "ystem =ysfunction

4.9.2


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destruction of the lacrimal gland.

G Altered composition of the tear film. The composition

of the tear film can

alter due to vitamin deficiency, medications (such asoral contraceptives

and retinoids), or certain environmental influences (such

as nicotine,

smog, or air conditioning). The tear film breaks up too

1uickly and causes

corneal drying.

=ry eyes can represent a disorder in and of itself.

"ymptoms: +atients complain of burning, reddened eyes,

and excessive lacrimation

(reflex lacrimation) from only slight environmental causes

such as

$ind, cold, lo$humidity, or reading for an extended

period of time. foreignbody sensation is also present. These symptoms may be

accompanied by

intense pain. &yesight is usually minimally compromised

if at all.

=iagnostic considerations: *ften there is a discrepancy

bet$een the minimal

clinical findings that the ophthalmologist can establishand the intense

symptoms reported by the patient. %esults fromSchirmer

tear testing usually


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sho$ reductions of the $atery component of tears, and the

tear rea!"up

time ($hich provides information about the mucin

content of the tear film$hich is important for its stability) is reduced. 5alues of

at least 26 seconds

are normal@ the tear break-up time in keratoconjunctivitis

sicca is less than 3

seconds.

Slit lamp examination$ill reveal dilated conjunctival

vessels and minimal

pericorneal injection. tear film meniscus cannot be

demonstrated on the

lo$er eyelid margin, and the lo$er eyelid $ill push the

conjunctiva along in

folds in front of it.

4 acrimal "ystemang, *phthalmology I A666 Thieme

ll rights reserved. !sage subject to terms and conditions

of license.

F4

#nsevere cases the eye $ill be reddened, and the tear film

$ill contain thick

mucus and small filaments that proceed from a superficialepithelial lesion

(filamentary keratitis@ see ig. 3.11). The corneal lesion

can be demonstrated


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$ith fluorescein d#e. #n less severe cases the eye $ill

only be reddened,

although application of fluorescein dye $ill reveal corneal

lesions (superficialpunctate keratitis@ see p. 24E). The rose engal test (see

p. 3A) and impression

c#tolog# (see p. 34) are additional diagnostic tests that are

useful in evaluating

persistent cases.

Treatment: =epending on the severity of findings,

artificial tear solutions in

varying viscosities are prescribed. These range

fromeyedrops to high-viscosity

long-acting gels that may be applied every hour or every

half hour,

depending on the severity of the disorder. #n persistent

cases, the puncta canbe temporarily closed $ith silicone punctal plugs (ig.

4.11) to at least retain

the fe$tears that are still produced. Surgical oliteration

of the puncta may

be indicated in severe cases.

+atients should also be informed about the possibility of

installing an airhumidifier in the home and redirecting blo$ers in

automobiles to avoid

further drying of the eyes. =ry eyes in $omen may also

be due to hormonal


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changes, and a g#necologist should e consulted

regarding the patient?s hormonal

status.

+rognosis: The prognosis is good for those treatmentsdiscussed here.

o$ever, the disorder cannot be completely healed.

Treatment of dr# e#es.

ig. 4.11 Treatment

can be augmented

by temporarily

closing

the puncta $ith

silicone punctal

plugs.

4.9 acrimal "ystem =ysfunction

Fisiologi Tear Film

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