Ophthalmology A Short Textbook - part 2 pot

0.8 µm Epithelium with microvilli and folds Oily layer, 0.1 µm Meibomian glands Lacrimal gland Water layer, 8 µm Conjunctivalgoblet cells Mucin layer, 0.8 µm Fig.. Position, structure, a

Cavernous hemangioma.

Fig 2.25 The congenital vascular

anomaly occurs as a facial lesion mostcommonly occur in the eyelids The le-sion regresses spontaneously in ap-proximately 70% of all cases

Symptoms:Hemangiomas include capillary or superficial, cavernous, anddeep forms

Diagnostic considerations:Hemangiomas can be compressed, and the skinwill then appear white

Differential diagnosis:Nevus flammeus:This is characterized by a sharplydemarcated bluish red mark (“port-wine” stain) resulting from vascularexpansion under the epidermis (not a growth or tumor)

Treatment:A watch-and-wait approach is justified in light of the high rate of

spontaneous remission (approximately 70%) Where there is increased risk of amblyopia due to the size of the lesion, cryotherapy, intralesional steroidinjections, or radiation therapy can accelerate regression of the hemangioma.Prognosis:Generally good

2.7.1.7 Neurofibromatosis (Recklinghausen’s Disease)

Definition

A congenital developmental defect of the neuroectoderm gives rise to neural

tumors and pigment spots (café au lait spots).

Neurofibromatosis is regarded as a phacomatosis (a developmental disorder

involving the simultaneous presence of changes in the skin, central nervoussystem, and ectodermal portions of the eye)

Symptoms and diagnostic considerations:The numerous tumors are soft,broad-based, or pediculate, and occur either in the skin or in subcutaneoustissue, usually in the vicinity of the upper eyelid

They can reach monstrous proportions and present as elephantiasis of the eyelids(Fig 2.26).

Treatment: Smaller fibromas can be easily removed by surgery Largertumors always entail a risk of postoperative bleeding and recurrence On the

whole, treatment is difficult.

Neurofibroma.

Fig 2.26 Larger fibromas can lead to

elephantiasis of the eyelids

2.7 Tumors

Epidemiology:Approximately 90% of all malignant eyelid tumors are basalcell carcinomas Their incidence increases with age In approximately 60% of

all cases they are localized on the lower eyelid Morbidity in sunny countries

is 110 cases per 100 000 persons (in central Europe approximately 20 per

100 000 persons) Dark-skinned people are affected significantly less often.

Gender is not a predisposing factor

Etiology:Causes of basal cell carcinoma may include a genetic disposition

Increased exposure to the sun’s ultraviolet radiation, carcinogenic substances (such as arsenic), and chronic skin damage can also lead to an increased inci-

dence Basal cell carcinomas arise from the basal cell layers of the epidermisand the sebaceous gland hair follicles, where their growth locally destroystissue

Symptoms:Typical characteristics include a firm, slightly raised margin (a halo resembling a string of beads ) with a central crater and superficial vascular- izationwith an increased tendency to bleed (Fig 2.27).

Ulceration with “gnawing” peripheral proliferation is occasionally

referred to as an ulcus rodens; an ulcus terebans refers to deep infiltration with

invasion of cartilage and bone

Diagnostic considerations:The diagnosis can very often be made on thebasis of clinical evidence A biopsy is indicated if there is any doubt

Loss of the eyelashes in the vicinity of the tumor always suggests nancy

malig-Treatment:The lesion is treated by surgical excision within a margin ofhealthy tissue This is the safest method If a radical procedure is not feasible,

Basal cell carcinoma.

Fig 2.27 A halo

resembling astring of beads,superficial vascu-larization, and acentral craterwith a tendency

to bleed arecharacteristicsigns of this mod-erately malignanttumor

47the only remaining options are radiation therapy or cryotherapy with liquidnitrogen.

Prognosis:The changes of successful treatment by surgical excision are verygood Frequent follow-up examinations are indicated

The earlier a basal cell carcinoma is detected, the easier it is to remove.2.7.2.2 Squamous Cell Carcinoma

This is the second most frequently encountered malignant eyelid tumor The

carcinoma arises from the epidermis, grows rapidly and destroys tissue It canmetastasize into the regional lymph nodes Remote metastases are rarer The

treatment of choiceis complete surgical removal

2.7.2.3 Adenocarcinoma

The rare adenocarcinoma arises from the meibomian glands or the glands of

Zeis The firm, painless swelling is usually located in the upper eyelid and is

mobile with respect to the skin but not with respect to the underlying tissue

In its early stages it can be mistaken easily for a chalazion (see p 39) The

lesion can metastasize into local lymph nodes

An apparent chalazion that cannot be removed by the usual surgicalprocedure always suggests a suspected adenocarcinoma

The treatment of choice is complete surgical removal.

2.7 Tumors

Peter Wagner and Gerhard K Lang

The lacrimal system (Fig 3.1) consists of two sections:

❖ Structures that secrete tear fluid

❖ Structures that facilitate tear drainage

Anatomy of the lacrimal system.

Orbital part of the

lacrimal gland

Plica semilunaris Superior punctum lacrimale

Lacrimal sac

Nasolacrimal

Superior lacrimal canaliculus

Fundus of the lacrimal sac

Structure of the tear film.

Oily layer (approx 0.1 µm)

Mucin layer (approx 0.8 µm)

Epithelium with microvilli

and folds

Oily layer, 0.1 µm

Meibomian glands

Lacrimal gland

Water layer,

8 µm Conjunctivalgoblet cells Mucin layer,

0.8 µm

Fig 3.2 The tear film is composed of three layers:

❖An oily layer (prevents rapid desiccation)

❖A watery layer (ensures that the cornea remains clean and smooth for optimaltransparency)

❖A mucin layer (like the oily outer layer, it stabilizes the tear film)

Position, structure, and nerve supply of the lacrimal gland:The lacrimal gland is about the size of a walnut; it lies beneath the superior temporal mar-

gin of the orbital bone in the lacrimal fossa of the frontal bone and is neither visible nor palpable.A palpable lacrimal gland is usually a sign of a pathologicchange such as dacryoadenitis The tendon of the levator palpebrae muscle

divides the lacrimal gland into a larger orbital part (two-thirds) and a smaller palpebral part(one-third) Several tiny accessory lacrimal glands (glands of Krause and Wolfring) located in the superior fornix secrete additional serous

tear fluid

The lacrimal gland receives its sensory supply from the lacrimal nerve Its

parasympathetic secretomotor nerve supply comes from the nervus dius.The sympathetic fibers arise from the superior cervical sympatheticganglion and follow the course of the blood vessels to the gland

interme-Tear film:The tear film (Fig 3.2) that moistens the conjunctiva and cornea is composed of three layers:

1 The outer oily layer (approximately 0.1µm thick) is a product of the

mei-bomian glands and the sebaceous glands and sweat glands of the margin of

the eyelid.The primary function of this layer is to stabilize the tear film.With its hydrophobic properties, it prevents rapid evaporation like a layer

of wax

2 The middle watery layer (approximately 8µm thick) is produced by the

lacrimal gland and the accessory lacrimal glands (glands of Krause and

Wolfring) Its task is to clean the surface of the cornea and ensure mobility

of the palpebral conjunctiva over the cornea and a smooth corneal surface

for high-quality optical images.

3 The inner mucin layer (approximately 0.8µm thick) is secreted by the

goblet cells of the conjunctiva and the lacrimal gland It is hydrophilic with respect to the microvilli of the corneal epithelium, which also helps to sta- bilize the tear film.This layer prevents the watery layer from forming beads

on the cornea and ensures that the watery layer moistens the entire surface

of the cornea and conjunctiva.

Lysozyme, beta-lysin, lactoferrin, and gamma globulin (IgA) are tear-specific

proteins that give the tear fluid antimicrobial characteristics.

Tear drainage:The shingle-like arrangement of the fibers of the orbicularis oculi muscle (supplied by the facial nerve) causes the eye to close progress-

ively from lateral to medial instead of the eyelids simultaneously closing

along their entire length This windshield wiper motion moves the tear fluid

medially across the eye toward the medial canthus (Figs 3.3a–c).

The superior and inferior puncta lacrimales collect the tears, which then drain through the superior and inferior lacrimal canaliculi into the lacrimal sac From there they pass through the nasolacrimal duct into the inferior concha (see Fig 3.1).

Combined function of the orbicularis oculi muscle and the lower lacrimal system.

Opening the eye

3.1 Basic Knowledge

Measuring tear secretion with Schirmer tear testing.

Fig 3.4 A strip

of litmus paper isfolded over andinserted into theconjunctival sac

of the temporalthird of the lowereyelid Normally,

at least 15 mm ofthe paper shouldturn blue withinfive minutes

3.2.1 Evaluation of Tear Formation

Schirmer tear testing:This test (Fig 3.4) provides information on the tity of watery component in tear secretion.

quan-❖ Test:A strip of litmus paper is inserted into the conjunctival sac of the poral third of the lower eyelid

tem-❖ Normal:After about five minutes, at least 15 mm of the paper should turnblue due to the alkaline tear fluid

❖ Abnormal:Values less than 5 mm are abnormal (although they will notnecessarily be associated with clinical symptoms)

The same method is used after application of a topical anesthetic to evaluate normal secretion without irritating the conjunctiva.

Tear break-up time (TBUT):This test evaluates the stability of the tear film.

❖ Test:Fluorescein dye (10µl of a 0.125% fluorescein solution) is added to theprecorneal tear film The examiner observes the eye under 10 – 20 powermagnification with slit lamp and cobalt blue filter and notes when the first

signs of drying occur (i) without the patient closing the eye and (ii) with the patient keeping the eye open as he or she would normally.

❖ Normal: TBUT of at least 10 seconds is normal.

Rose bengal test:Rose bengal dyes dead epithelial cells and mucin This test

has proven particularly useful in evaluating dry eyes (keratoconjunctivitis

sicca) as it reveals conjunctival and corneal symptoms of desiccation

53Impression cytology: A Millipore filter is fastened to a tonometer andpressed against the superior conjunctiva with 20 – 30 mm Hg of pressure for

two seconds The density of goblet cells is estimated under a microscope

(normal density is 20 – 45 goblet cells per square millimeter of epithelial

sur-face) The number of mucus-producing goblet cells is reduced in various orders such as keratoconjunctivitis sicca, ocular pemphigoid, and xeroph-thalmia

dis-3.2.2 Evaluation of Tear Drainage

Conjunctival fluorescein dye test:Normal tear drainage can be

demon-strated by having the patient blow his or her nose into a facial tissue followingapplication of a 2% fluorescein sodium solution to the inferior fornix.Probing and irrigation:These examination methods are used to locate ste- noses After application of a topical anesthetic, a conical probe is used to

dilate the punctum Then the lower lacrimal system is flushed with a

physio-logic saline solution introduced through a blunt cannula (Figs 3.5 a and b) If

the passage is unobstructed, the solution will drain freely into the nose.

Canalicular stenosis will result in reflux through the irrigated punctum

If the stenosis is deeper, reflux will occur through the opposite punctum

(Fig 3.6).

A probe can be used to determine the site of the stricture, and possibly to

eliminate obstructions (Fig 3.7).

Radiographic contrast studies:Radiographic contrast medium is instilled in

the same manner as the saline solution These studies demonstrate the shape, position, and size of the passage and possible obstructions to drainage.

Digital substraction dacryocystography:These studies demonstrate onlythe contrast medium and image the lower lacrimal system without superim-

posed bony structures They are particularly useful as preoperative tic studies (Fig 3.8).

diagnos-Lacrimal endoscopy:Fine endoscopes now permit direct visualization of

3.2 Examination Methods

Irrigation of the lower lacrimal system under topical anesthesia.

Figs 3.5 a and b

First the tum is dilated byrotating a conicalprobe Then thelacrimal passage

punc-is flushed with aphysiologic salinesolution The ex-aminer should beparticularly alert

to good drainage

or possible reflux

a

b

Fig 3.6 The lower lacrimal system

should be irrigated with care by an perienced ophthalmologist Failure tolocate the passage will inflate the eyelidand provide no diagnostic information.3.2 Examination Methods

ex-Opening a stenosis of the lower lacrimal system with a probe.

Figs 3.7 a – c After application of a topical anesthetic, the probe is carefully

intro-duced into the lower lacrimal system The puncta are dilated and then the valve of

Hasner is opened (a and b) A dye solution can then be introduced to verify patency

of the lower lacrimal system (c) In infants six months or older, the procedure is best

performed under short-acting general anesthesia

a

c

b

Radiographic image of the lower lacrimal system.

Fig 3.8 Digital

substractiondacryocystogra-phy images thelower lacrimalsystem and candemonstrate apossible stenosis(arrow) withoutsuperimposedbony structures

3.3.1 Dacryocystitis

Inflammation of the lacrimal sac is the most frequent disorder of the lower

lacrimal system It is usually the result of obstruction of the nasolacrimal duct

and is unilateral in most cases.

3.3.1.1 Acute Dacryocystitis

Epidemiology:The disorder most frequently affects adults between the ages

of 50 and 60

Etiology:The cause is usually a stenosis within the lacrimal sac The retention

3.3 Disorders of the Lower Lacrimal System

Acute dacryocystitis.

Fig 3.9 Typical

symptoms clude highly in-flamed, painfulswelling in the vi-cinity of the lacri-mal sac

in-Acute inflammation that has spread to the surrounding tissue of theeyelids and cheek entails a risk of sepsis and cavernous sinus thrombo-sis, which is a life-threatening complication

Diagnostic considerations: Radiographic contrast studies or digital straction dacryocystography can visualize the obstruction for preoperativeplanning These studies should be avoided during the acute phase of the dis-order because of the risk of pathogen dissemination

sub-Differential diagnosis:

❖ Hordeolum (small, circumscribed, nonmobile inflamed swelling)

❖ Orbital cellulitis (usually associated with reduced motility of the eyeball).Treatment: Acute cases are treated with local and systemic antibiotics

according to the specific pathogens detected Disinfectant compresses (such as

a 1 : 1000 Rivanol solution) can also positively influence the clinical course of

the disorder Pus from a fluctuating abscess is best drained through a stab sionfollowing cryoanesthesia with a refrigerant spray

inci-Treatment after acute symptoms have subsided often requires surgery (dacryocystorhinostomy; Figs 3.10a–c) to achieve persistent relief Also

known as a lower system bypass, this operation involves opening the lateralwall of the nose and bypassing the nasolacrimal duct to create a direct con-nection between the lacrimal sac and the nasal mucosa

Figs 3.10 a – c A skin incision is made,

and the orbital rim is exposed Then awindow is opened to expose the nasalmucosa The nasal mucosa and the lacri-mal sac are both incised in an H-shapeand door-like flaps are raised The ante-rior and posterior mucosal flaps are thensutured together This creates a newdrainage route for the tear fluid that by-passes the nasolacrimal duct

3.3 Disorders of the Lower Lacrimal System

Chronic inflammation of the lacrimal sac can lead to a serpiginous neal ulcer.

cor-Treatment:Surgical intervention is the only effective treatment in the vastmajority of cases This involves either a dacryocystorhinostomy (creation of adirect connection between the lacrimal sac and the nasal mucosa; see Figs

3.10a–c) or removal of the lacrimal sac.

3.3.1.3 Neonatal Dacryocystitis

Etiology:Approximately 6% of newborns have a stenosis of the mouth of the

nasolacrimal duct due to a persistent mucosal fold (lacrimal fold or valve of

Hasner) The resulting retention of tear fluid provides ideal growth conditionsfor bacteria, particularly staphylococci, streptococci, and pneumococci.Symptoms and diagnostic considerations: Shortly after birth (usually

within two to four weeks), pus is secreted from the puncta The disease tinues subcutaneously and pus collects in the palpebral fissure The conjunc- tiva is not usually involved.

con-Differential diagnosis:

❖ Gonococcal conjunctivitis and inclusion conjunctivitis (see Fig 4.3).

❖ Silver catarrh (harmless conjunctivitis with slimy mucosal secretion lowing Credé’s method of prophylaxis with silver nitrate)

fol-Treatment:During the first few weeks, the infant should be monitored for

spontaneous opening of the stenosis During this period, antibiotic and inflammatory eyedrops and nose drops (such as erythromycin and xylo-metazoline 0.5% for infants) are administered

anti-If symptoms persist, irrigation or probing under short-acting general

anes-thesia may be indicated (see Figs 3.7a–c).

Often massaging the region several times daily while carefully applyingpressure to the lacrimal sac will be sufficient to open the valve of Hasnerand eliminate the obstruction

613.3.2 Canaliculitis

Definition

This usually involves inflammation of the canaliculus.

Epidemiology and etiology:Genuine canaliculitis is rare Usually a stricture will be present and the actual inflammation proceeds from the conjunctiva.

Actinomycetes (fungoid bacteria) often cause persistent purulent granularconcrements that are difficult to express

Symptoms and diagnostic considerations:The canaliculus region is len, reddened, and often tender to palpation Pus or granular concrementscan be expressed

swol-Treatment:The disorder is treated with antibiotic eyedrops and ointmentsaccording to the specific pathogens detected in cytologic smears Successfultreatment occasionally requires surgical incision of the canaliculus

3.3.3 Tumors of the Lacrimal Sac

Epidemiology:Tumors of the lacrimal sac are rare but are primarily nantwhen they do occur They include papillomas, carcinomas, and sar-comas

malig-Symptoms and diagnostic considerations:Usually the tumors cause lateral painless swelling followed by dacryostenosis

uni-Diagnostic considerations:The irregular and occasionally bizarre form ofthe structure in radiographic contrast studies is typical Ultrasound, CT, MRI,and biopsy all contribute to confirming the diagnosis

Differential diagnosis:Chronic dacryocystitis (see above), mucocele of theethmoid cells

Treatment:The entire tumor should be removed

3.3 Disorders of the Lower Lacrimal System

3.4 Lacrimal System Dysfunction

prevalent in regions with higher levels of environmental pollution

Etiology:Keratoconjunctivitis sicca results from dry eyes, which may be due

to one of two causes:

❖ Reduced tear production associated with certain systemic disorders (such

as Sjögren’s syndrome and rheumatoid arthritis) or as a result of atrophy ordestruction of the lacrimal gland

❖ Altered composition of the tear film The composition of the tear film can

alter due to vitamin A deficiency, medications (such as oral contraceptivesand retinoids), or certain environmental influences (such as nicotine,smog, or air conditioning) The tear film breaks up too quickly and causescorneal drying

Dry eyes can represent a disorder in and of itself.

Symptoms:Patients complain of burning, reddened eyes, and excessive mation (reflex lacrimation) from only slight environmental causes such aswind, cold, low humidity, or reading for an extended period of time A foreignbody sensation is also present These symptoms may be accompanied byintense pain Eyesight is usually minimally compromised if at all

lacri-Diagnostic considerations:Often there is a discrepancy between the mal clinical findings that the ophthalmologist can establish and the intense symptoms reported by the patient.Results from Schirmer tear testing usually show reductions of the watery component of tears, and the tear break-up time (which provides information about the mucin content of the tear film

mini-which is important for its stability) is reduced Values of at least 10 secondsare normal; the tear break-up time in keratoconjunctivitis sicca is less than 5seconds

Slit lamp examination will reveal dilated conjunctival vessels and minimal

pericorneal injection A tear film meniscus cannot be demonstrated on thelower eyelid margin, and the lower eyelid will push the conjunctiva along infolds in front of it

In severe cases the eye will be reddened, and the tear film will contain thick

mucus and small filaments that proceed from a superficial epithelial lesion

(filamentary keratitis; see Fig 5.11) The corneal lesion can be demonstrated with fluorescein dye In less severe cases the eye will only be reddened,

although application of fluorescein dye will reveal corneal lesions (superficial

punctate keratitis; see p 138) The rose bengal test (see p 52) and impression cytology (see p 53) are additional diagnostic tests that are useful in evaluat-

ing persistent cases

Treatment:Depending on the severity of findings, artificial tear solutions in

varying viscosities are prescribed These range from eyedrops to ity long-acting gels that may be applied every hour or every half hour,depending on the severity of the disorder In persistent cases, the puncta can

high-viscos-be temporarily closed with silicone punctal plugs (Fig 3.11) to at least retain the few tears that are still produced Surgical obliteration of the puncta may

be indicated in severe cases

Patients should also be informed about the possibility of installing an air humidifier in the home and redirecting blowers in automobiles to avoid

further drying of the eyes Dry eyes in women may also be due to hormonal

changes, and a gynecologist should be consulted regarding the patient’s

aug-3.4 Lacrimal System Dysfunction

3.4.2 Illacrimation

Illacrimation or epiphora may be due to hypersecretion from the lacrimal gland However, it is more often caused by obstructed drainage through the lower lacrimal system.

Causes of hypersecretion:

❖ Emotional distress(crying)

❖ Increased irritation of the eyes(by smoke, dust, foreign bodies, injury, orintraocular inflammation) leads to excessive lacrimation in the context ofthe defensive triad of blepharospasm, photosensitivity, and epiphora

Causes of obstructed drainage:

❖ Stricture or stenosis in the lower lacrimal system

❖ Eyelid deformity (eversion of the punctum lacrimale, ectropion, orentropion)

3.5.1 Acute Dacryoadenitis

Definition

Acute inflammation of the lacrimal gland is a rare disorder characterized by

intense inflammation and extreme tenderness to palpation

Etiology:The disorder is often attributable to pneumococci and cocci, and less frequently to streptococci There may be a relationshipbetween the disorder and infectious diseases such as mumps, measles, scar-let fever, diphtheria, and influenza

staphylo-Symptoms and diagnostic considerations:Acute dacryoadenitis usually

occurs unilaterally The inflamed swollen gland is especially tender to tion.

palpa-The upper eyelid exhibits a characteristic S-curve (Fig 3.12).

Differential diagnosis:

❖ Internal hordeolum (smaller and circumscribed)

❖ Eyelid abscess (fluctuation)

❖ Orbital cellulitis (usually associated with reduced motility of the eyeball).Treatment:This will depend on the underlying disorder Moist heat, disinfect- ant compresses (Rivanol), and local antibiotics are helpful.

Clinical course and prognosis:Acute inflammation of the lacrimal gland is

characterized by a rapid clinical course and spontaneous healing within eight

to ten days The prognosis is good, and complications are not usually to beexpected

3.5.2 Chronic Dacryoadenitis

Etiology:The chronic form of inflammation of the lacrimal gland may be the

result of an incompletely healed acute dacryoadenitis Diseases such as

tuber-culosis, sarcoidosis, leukemia, or lymphogranulomatosis can be causes ofchronic dacryoadenitis

Bilateral chronic inflammation of the lacrimal and salivary glands isreferred to as Mikulicz’s syndrome

Symptoms and diagnostic considerations:Usually there is no pain Thesymptoms are less pronounced than in the acute form However, the S-curvedeformity of the palpebral fissure resulting from swelling of the lacrimal

gland is readily apparent (see Fig 3.12).

Acute dacryoadenitis.

Fig 3.12

CharacteristicS-curve of theupper eyelid.3.5 Disorders of the Lacrimal Gland

3.5.3 Tumors of the Lacrimal Gland

Epidemiology:Tumors of the lacrimal gland account for 5 – 7% of orbital

neo-plasms Lacrimal gland tumors are much rarer in children (approximately 2%

of orbital tumors) The relation of benign to malignant tumors of the lacrimal

gland specified in the literature is 10 : 1 The most frequent benign epithelial

lacrimal gland tumor is the pleomorphic adenoma Malignant tumors

include the adenoid cystic carcinoma and pleomorphic adenocarcinoma.

Etiology:The WHO classification of 1980 divides lacrimal gland tumors intothe following categories:

I Epithelial tumors

II Tumors of the hematopoietic or lymphatic tissue

III Secondary tumors

IV Inflamed tumors

V Other and unclassified tumors

Symptoms:Tumors usually grow very slowly After a while, they displace the

eyeball inferiorly and medially, which can cause double vision

Diagnostic considerations:Testing motility provides information about the

infiltration of the tumor into the extraocular muscles or mechanical changes

in the eyeball resulting from tumor growth The echogenicity of the tumor in

ultrasound studies is an indication of its consistency CT and MRI studies

show the exact location and extent of the tumor A biopsy will confirmwhether it is malignant and what type of tumor it is

Treatment:To the extent that this is possible, the entire tumor should beremoved; orbital exenteration (removal of the entire contents of the orbit)may be required Systemic administration of corticosteroids is indicated forunspecific tumors

Prognosis:This depends on the degree of malignancy of the tumor Adenoidcystic carcinomas have the most unfavorable prognosis

Gerhard K Lang and Gabriele E Lang

Structure of the conjunctiva(Fig 4.1): The conjunctiva is a thin vascular

mucous membrane that normally of shiny appearance It forms the

conjunc-tival sac together with the surface of the cornea The bulbar conjunctiva is

loosely attached to the sclera and is more closely attached to the limbus of thecornea There the conjunctival epithelium fuses with the corneal epithelium

The palpebral conjunctiva lines the inner surface of the eyelid and is firmly

attached to the tarsus The loose palpebral conjunctiva forms a fold in the

conjunctival fornix, where it joins the bulbar conjunctiva A

half-moon-shaped fold of mucous membrane, the plica semilunaris, is located in themedial corner of the palpebral fissure This borders on the lacrimal caruncle,which contains hairs and sebaceous glands

Function of the conjunctival sac:The conjunctival sac has three main tasks:

1 Motility of the eyeball The loose connection between the bulbar

conjunc-tiva and the sclera and the “spare” conjuncconjunc-tival tissue in the fornices allowthe eyeball to move freely in every direction of gaze

2 Articulating layer The surface of the conjunctiva is smooth and moist to

allow the mucous membranes to glide easily and painlessly across eachother The tear film acts as a lubricant

3 Protective function The conjunctiva must be able to protect against

pathogens Follicle-like aggregations of lymphocytes and plasma cells (thelymph nodes of the eye) are located beneath the palpebral conjunctiva and

in the fornices Antibacterial substances, immunoglobulins, interferon,

Anatomy of the conjunctiva.

Glands of Krause Glands of Wolfring

Accessory lacrimal glands:

Meibomiangland

BulbarconjunctivaConjunctivalfornixPalpebralconjunctivaSurface of thecornea (functions

as a part of theconjunctival sac)

Fig 4.1 The conjunctiva consists of the bulbar conjunctiva, the conjunctival

for-nices, and the palpebral conjunctiva The surface of the cornea functions as the floor

of the conjunctival sac

Inspection:The bulbar conjunctiva can be evaluated by direct inspection under a focused light Normally it is shiny and transparent The other parts of the conjunctiva will not normally be visible They can be inspected by evert-

ing the upper or lower eyelid (see eyelid eversion below)

69Dye staining:Defects and tears in the conjunctiva or cornea can be visualized

by applying a drop of fluorescein dye or rose bengal and inspecting the eye

under illumination with a cobalt blue filter (see Fig 5.11, p 139).

Eyelid eversion:Even the non-ophthalmologist must be familiar with thetechnique of everting the upper or lower eyelid This is an important exami-nation method in cases in which the conjunctival sac requires cleaning orirrigation, such as removing a foreign body or rendering first aid after achemical injury See Chapter 1 for a detailed description of the examinationmethod

to sun, wind, and dust foster the occurrence of the disorder

Symptoms:Pingueculum does not cause any symptoms

Diagnostic considerations:Inspection will reveal grayish yellow thickening

at 3 o’clock and 9 o’clock on the limbus The base of the triangular thickening(often located medially) will be parallel to the limbus of the cornea; the tip

will be directed toward the angle of the eye (Fig 4.2).

Differential diagnosis:A pingueculum is an unequivocal finding

Treatment:No treatment is necessary

4.3 Conjunctival Degeneration and Aging Changes

Fig 4.2

Harm-less triangularpingueculumwhose base isparallel to thecornea (arrow)

Etiology:Histologically, a pterygium is identical to a pinguecula However, itdiffers in that it can grow on to the cornea; the gray head of the pterygium will

grow gradually toward the center of the cornea (Fig 4.3a) This progression is

presumably the result of a disorder of Bowman’s layer of the cornea, which

pro-vides the necessary growth substrate for the pterygium

Symptoms and diagnostic considerations: A pterygium only producessymptoms when its head threatens the center of the cornea and with it the

visual axis (Fig 4.3b) Tensile forces acting on the cornea can cause severe

corneal astigmatism A steadily advancing pterygium that includes scarredconjunctival tissue can also gradually impair ocular motility; the patient willthen experience double vision in abduction

Differential diagnosis:A pterygium is an unequivocal finding

Treatment:Treatment is only necessary when the pterygium produces thesymptoms discussed above Surgical removal is indicated in such cases Thehead and body of the pterygium are largely removed, and the sclera is leftopen at the site The cornea is then smoothed with a diamond reamer or anexcimer laser (a special laser that operates in the ultraviolet range at awavelength of 193 nm)

Clinical course and prognosis:Pterygia tend to recur Keratoplasty is cated in such cases to replace the diseased Bowman’s layer with normaltissue Otherwise the diseased Bowman’s layer will continue to provide agrowth substrate for a recurrent pterygium

4.3.4 Subconjunctival Hemorrhage

Extensive bleeding under the conjunctiva (Fig 4.4) frequently occurs with

conjunctival injuries (for obtaining a history in trauma cases, see Chapter 18,conjunctival laceration) Subconjunctival hemorrhaging will also often occurspontaneously in elderly patients (as a result of compromised vascular struc-tures in arteriosclerosis), or it may occur after coughing, sneezing, pressing,bending over, or lifting heavy objects Although these findings are often very

unsettling for the patient, they are usually harmless and resolve

spon-taneously within two weeks The patient’s blood pressure and coagulationstatus need only be checked to exclude hypertension or coagulation disorderswhen subconjunctival hemorrhaging occurs repeatedly

4.3.5 Calcareous Infiltration

A foreign-body sensation in the eye is often caused by white punctate

concre-ments on the palpebral conjunctiva These concreconcre-ments are the calcified tents of goblet cells, accessory conjunctival and lacrimal glands, or mei-bomian glands where there is insufficient drainage of secretion These cal-careous infiltrates can be removed with a scalpel under topical anesthesia.4.3.6 Conjunctival Xerosis

Epidemiology:Due to the high general standard of nutrition, this disorder is

Conjunctival xerosis due to vitamin a deficiency.

Fig 4.5 a

Kerat-inization of thesuperficialepithelial cellscauses the sur-face of the con-junctiva to loseits luster

b The keratinized

epithelial cells dieand createcharacteristicBitot’s spots inthe palpebral fis-sure

4.3 Conjunctival Degeneration and Aging Changes