Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

A CASE OF PTOSIS

CASE DESCRIPTION

Age and sex. Ptosis may be congenital or acquired. Acquired ptosis may occur at any age in either sex. History. It should include age of onset, family history, history of trauma, eye surgery, and variability in degree of ptosis.

Examination should include:

1.Inspection to note:

True ptosis or pseudoptosis

Unilateral or bilateral ptosis

Eyelid crease and function of orbicularis

Presence of Jaw winking phenomenon

Associated weakness of extraocular muscles

Bell’s phenomenon

2.Measurement of degree of ptosis

3.Assessment of levator function

4.Special investigations for acquired ptosis For details see page 357

RELATED QUESTIONS

What is ptosis ?

Abnormal drooping of the upper eyelids is called ptosis. Normally upper lid covers about upper onesixth (2 mm) of the cornea. Therefore, in ptosis it covers more than 2 mm.

What are the types of ptosis?

I.Congenital ptosis which may be:

1.Simple congenital ptosis (not associated with any other anomaly) (Fig.14.32A).

2.Congenital ptosis with associated weakness of the superior rectus muscle.

3.As a part of blepharophimosis syndrome (Fig.14.32B).

4.Congenital synkinetic ptosis (Marcus Gunn jaw winking ptosis).

II.Acquired ptosis includes:

1.Neurogenic ptosis

2.Myogenic ptosis

3.Aponeurotic ptosis

4.Mechanical ptosis

How do you grade ptosis ?

Depending upon the amount of ptosis in mm, it is graded as follows:

1.Mild ptosis (2 mm)

2.Moderate ptosis (3 mm)

3.Severe ptosis (4 mm).

How do you grade levator function?

Depending upon the amount of lid excursion caused by levator muscle (Burke’s method), its function is graded as follows:

Which test is carried out to confirm the diagnosis in a patient with ptosis suspected of myasthenia gravis?

Tensilon or edrophonium test.

Which test is carried out in a patient suspected of Horner’s syndrome?

Phenylephrine test.

Name the three basic surgical procedures for ptosis correction.

1.Fasanella - Servat operation

2.Levator resection operation

3.Frontalis sling operation

Name the common lid tumours.

I.Benign tumours

1.Simple papilloma

2.Naevus

3.Haemangioma

4.Neurofibroma

II.Precancerous conditions

1.Solar keratosis

2.Carcinoma in-situ

3.Xeroderma pigmentosa III. Malignant tumours

1.Squamous-cell carcinoma

2.Basal-cell carcinoma

3.Malignant melanoma

4.Sebaceous gland carcinoma

Which is the most common malignant tumour of the lids?

Basal-cell carcinoma

Which is the most common site for occurrence of basal cell carcinoma ?

Medial canthus.

What is the structure of an eyelid ?

Each eyelid from anterior to posterior consists of the following layers:

1.Skin

2.Subcutaneous areolar tissue

3.Layer of striated muscle (orbicularis oculi and levator palpebrae superioris in upper lid only)

4.Submuscular areolar tissue

5.Fibrous layer (tarsal) plate and septum orbitale

6.Layer of non-striated muscle fibres (Muller’s muscle)

7.Conjunctiva

Name the glands of the eyelids.

1.Meibomian glands

2.Glands of Zeis

3.Glands of Moll

4.Accessory lacrimal glands of Wolfring

What are the causes of pseudoproptosis.

Anophthalmos

Enophthalmos

Phthisis bulbi

Atrophic bulbi

Trachoma (stage of sequelae)

Any tumour or nodule of upper lid

DISEASES OF THE LACRIMAL

APPARATUS

A CASE OF CHRONIC DACRYOCYSTITIS

CASE DESCRIPTION

Age and sex. The disease may occur at any age and in any sex. However, in general, females are much more commonly affected than males and the disease is more common between 40 and 60 years of age.

Presenting symptoms. A patient presents with a long standing history of watering from the eyes which may or may not be associated with a swelling at the inner cathus.

Ocular examination may reveal any of the following signs:

No swelling is seen at the medial canthus but regurgitation test is positive, i.e., a reflux of mucopurulent discharge from the puncta when pressure is applied over the lacrimal sac area.

A swelling may be seen at the medial canthus (Fig.15.8). Milky or gelatinous mucoid fluid regurgitates from the lower punctum on pressing the swelling (lacrimal mucocele).

Sometimes on pressing the swelling, a frank purulent discharge flows from the lower punctum (lacrimal pyocele).

Sometimes a swelling is seen at the inner canthus with a negative regurgitation test (encysted mucocele).

RELATED QUESTIONS

What are the causes of a watering eye ?

Watering from the eyes may occur either due to excessive lacrimation or may result from obstruction to the outflow of normally secreted tears (epiphora). The common causes of watering eye are listed at page 367.

Name the tests which you would like to carry out to evaluate a case of watering eye.

1.Examination with diffuse illumination under magnification to rule out causes of hyperlacrimation and punctal causes of epiphora

2.Regurgitation test for chronic dacryocystits

3.Fluorescein dye disappearance test (FDDT)

4.Lacrimal syringing test

5.Jone’s dye test I and II

6.Dacryocystography

7.Lacrimal scintillography

What is regurgitation test ?

In regurgitation test a steady pressure with index finger is applied over the lacrimal sac area above the medial palpebral ligament. Reflux of mucopurulent discharge (a positive regurgitation test) indicates chronic dacryocystitis with obstruction at the lower end of sac or nasolacrimal duct.

What are the causes of a negative regurgitation test?

Causes of a negative regurgitation test are:

Normal sac (no dacryocystitis)

Wrong site of pressure

Patient might have emptied the sac just before coming to the examiner’s chamber

Encysted mucocele

Internal fistula

Name the indications of lacrimal syringing.

1.Diagnostic indications:

Epiphora

For dacryocystography

2.Therapeutic indications:

Congenital dacryocystitis

Early cases of chronic catarrhal dacryocystitis

3.Prognostic:

After DCR operation

Describe the procedure and interpretations of the results of lacrimal syringing.

1.Topical anaesthesia is obtained by instilling 4 per cent Xylocaine in the conjunctival sac

2.Lower punctum is dilated with a punctum dilator

3.Normal saline is pushed into the lacrimal sac through the lower punctum with the help of a syringe and lacrimal cannula (Fig. 3.7-2) and results are interpreted as follows:

A free passage of saline through lacrimal passages into the nose indicates either no obstruction or partial obstruction.

In the presence of obstruction no fluid passes into the nose. When obstruction is in the nasolacrimal duct, the sac fills with the normal saline which refluxes from the upper punctum.

In case of lower canalicular obstruction, there will be immediate reflux of the saline through the lower punctum. Under these circumstances the procedure should be repeated through the upper punctum. A free passage of saline into the nose will confirm the blockage in the lower canaliculus while regurgitation back through the same punctum will indicate block at the level of common canaliculus.

What is dacryocystitis, how will you classify it?

Dacryocystits is inflammation of the lacrimal sac. It can be classified as follows:

1.Congenital dacryocystitis

2.Adult dacryocystitis which may occur as:

Chronic dacryocystitis, and

Acute dacryocystits

What is the aetiology of congenital dacryocystitis? How will you treat it ?

Congenital dacryocystitis follows stasis of secretions in the lacrimal sac due to congenital blockage in the nasolacrimal duct (usually a membranous occlusion at the lower end of NLD).

Its treatment, depending upon the age at which child is brought is as follows:

What is the treatment of choice in adulthood chronic dacryocystitis?

Dacryocystorhinostomy (DCR) operation is the operation of choice since it re-establishes the lacrimal drainage. When DCR is contraindictated, dacryocystectomy may be performed.

What is dacryocystectomy ? Enumerate its indications.

Dacryocystectomy is the excision of the lacrimal sac. It should be performed only when DCR is contraindicated as in following conditions:

1.Too young (less than 4 years) or too old (more than 60 years) a patient

2.Markedly shrunken and fibrosed sac

3.Tuberculosis, syphilis, leprosy or mycotic infection of the sac

4.Tumours of the sac

5.Gross nasal diseases like atrophic rhinitis

6.An unskilled surgeon, because it is said that a good ‘DCT’ is always better than a badly done ‘DCR’.

What are tears ?

Tears form the aqueous layer of tear film and are secreted by the accessory and main lacrimal glands. Tears mainly comprise water and small quantities of salts such as sodium chloride, sugar, urea and proteins. Therefore, it is alkaline and saltish in taste. It also contains antibacterial substances like lysozyme, betalysin and lactoferrin.

What are the layers of tear film ?

Wolf described the following three layers of tear film:

1.Mucous layer: It is the innermost and thinnest layer of tear film. It consists of mucin secreted by the conjunctival goblet cells. It converts the hydrophobic corneal surface into a hydrophilic one.

2.Aqueous layer: It consists of tears secreted by the main and accessory lacrimal glands and forms the main bulk of the tear film.

3.Lipid or oily layer: It consists of secretions of the meibomian, Zeis and Moll’s glands. It prevents the overflow of tears and retards their evaporation.

What are the functions of tear film ?

1.It keeps the cornea and conjunctiva moist

2.Provides oxygen to the corneal epithelium

3.It washes away debris and noxious irritants

4.It prevents infection due to presence of antibacterial substances

5.It facilitates movement of the lids over the globe.

What is dry eye ?

Dry eye per se is not a disease entity but a symptom complex occurring as a sequela to deficiency or abnormalities of the tear film.

What are the causes of dry eye ?

1.Aqueous deficiency dry eye (keratoconjunctivitis sicca — KCS)

Congenital alacrimia

Sjogren’s syndrome

Riley-Day syndrome

Idiopathic hyposecretion

2.Mucin deficiency dry eye

Hypovitaminosis A (xerophthalmia)

Stevens-Johnson syndrome

Trachoma

Chemical burns

3.Lipid abnormalities

Chronic blepharitis

Chronic meibomitis

4.Impaired eyelid function

Bell’s palsy

Exposure keratitis

Ectropion

5.Epitheliopathies of corneal surface

Name the important tear film tests performed to diagnose the dry eye.

Tear film break-up-time (BUT)

Schirmer 1 test

Rose bengal staining

What is tear film break-up time?

Tear film break-up time is the interval between a complete blink and appearance of the first randomly distributed dry spot on the corneal surface. Its normal values range between 15 and 35 seconds. Values less than 10 seconds employ an unstable tear film.

What is Schirmer 1 Test ?

Schirmer test measures the total tear secretions with the help of 5 × 35 mm strip of Whatman-42 filter paper. Its normal values are more than 15 mm of wetting of the filter paper strip in 5 minutes. Values between 5 and 10 mm are suggestive of mild to moderate keratoconjunctivitis sicca (KCS) and less than 5 mm of severe KCS.

What is Sjogren’s syndrome ?

Sjogren’s syndrome is an autoimmune disease usually occurring in women between 40 and 50 years of age. Its main feature is an aqueous deficiency dry eye (KCS). It occurs in two forms:

1.Primary Sjogren’s syndrome: In it, KCS is combined with xerostomia (dry mouth)

2.Secondary Sjogren’s syndrome: In it dry eye and /or dry mouth is associated with an autoimmune disease, commonly rheumatoid arthritis.

What is the treatment of dry eye?

1.Supplementation by artificial tear solution such as: 0.7 percent methylcellulose, 0.3 percent hypromellose or 1.4 percent polyvinyl alcohol.

2.Preservation of existing tears by punctal occlusions with collagen implants or electrocauterization

3.Mucolytics such as 5 percent acetylcysteine help by dispersing the mucous threads.

DISEASES OF THE ORBIT

A CASE OF PROPTOSIS

CASE DESCRIPTION

Presenting symptoms. A patient presents with a history of the bulging of the eyeball which may be gradually or rapidly progressive. It may or may not be associated with visual loss, diplopia, pain or other symptoms.

Ocular examination reveals outward protusion of the eyeball which may be:

Unilateral (Fig.16.7) or bilateral (Fig.16.11),

Axial or eccentric

Pulsatile or non-pulsatile

Reducible or non-reducible

May or may not be associated with lagophthalmos

RELATED QUESTIONS

What is proptosis and exophthalmos ?

Proptosis refers to forward displacement of the eyeball beyond the orbital margin. Though the word exophthalmos (out eye) is synonymous with proptosis; somehow it has become customary to use the term exophthalmos for the displacement associated with thyroid eye disease.

What are the causes of unilateral proptosis?

1.Congenital conditions

Dermoid cyst

Congenital cystic eyeball

Teratoma

2.Traumatic lesions

Orbital haemorrhage

Retained intraorbital foreign body

Traumatic aneurysm

3.Inflammatory lesions

Orbital cellulitis or abscess

Panophthalmitis

Cavernous sinus thrombosis

Pseudotumour

4.Circulatory disturbances and vascular lesions

Orbital varix

Aneurysm

5.Cysts of the orbit

Implantation cyst

Hydatid cyst

Cysticercus cellulosae

6.Tumours of the orbit, which may be

Primary tumours (arising from the various intraorbital structures)

Secondary tumours (invading from the surrounding structures)

Metastatic tumours from the distant primary tumours.

Enumerate the causes of bilateral proptosis.

1.Developmental anomalies of the skull

Oxycephaly

2.Inflammatory conditions

Mikulicz’s syndrome

Late stage of cavernous sinus thrombosis

3.Endocrine exophthalmos (most common cause) (Fig.16.11)

4.Orbital tumours, e.g.:

Lymphoma or lymphosarcoma

Secondaries from:

–Neuroblastoma

–Nephroblastoma

–Ewing’s sarcoma

–Leukaemic infiltration

5.Systemic diseases, e.g.:

Histiocytosis-X

Systemic amyloidosis

Xanthomatosis

Wegener’s granulomatosis

What are the causes of acute proptosis ?

1.Orbital emphysema following fracture of medial orbital wall

2.Orbital haemorrhage

3.Rupture of ethmoidal mucocele

What are the causes of intermittent proptosis?

1.Orbital varix (most common cause)

2.Periodic orbital oedema

3.Highlyvascular tumour

What are the causes of pulsatile proptosis ?

1.Caroticocavernous fistula (most common cause)

2.Saccular aneurysm of ophthalmic artery

3.Congenital orbital meningocele or meningoencephalocele

4.Hiatus in the orbital roof due to trauma, operation or that associated with neurofibromatosis

How will you investigate a case of proptosis ?

Evaluation of a case of proptosis includes the following:

I.Clinical evaluation

a)History

b)Local examination

(1)Inspection; (2) palpation; (3) auscultation; (4) transillumination; (5) visual acuity; (6) pupillary reactions; (7) fundoscopy; (8) ocular motility; (9) exophthalmometry

c)Systemic examination

II.Laboratory investigations

Thyroid function tests

Haematological tests

Stool examination for cysts and ova

Urine analysis

III.Roentgen examination

1.Plain radiograph of orbit

2.CT Scanning

3.Ultrasonography

4.Magnetic resonance imaging (MRI)

5.Carotid angiography

IV. Histopathological studies

1.Fine-needle aspiration biopsy (FNAB)

2.Incisional biopsy

3.Excisional biopsy

What is enophthalmos? Enumerate its causes.

Enophthalmos is the inward displacement of the eyeball. Its common causes are:

1.Congenital microphthalmos

2.Congenital maxillary hypoplasia

3.Traumatic blow-out fractures of the orbital floor

4.Post-inflammatory cicatrization of the extraocular muscles as in pseudotumour syndromes

5.Paralytic enophthalmos as seen in Horner’s syndrome

6.Atrophy of the orbital contents, e.g., senile atrophy of orbital fat, atrophy following irradiation of malignant tumours.

What is Graves’ ophthalmopathy ?

This is a term coined to denote typical ocular changes which include: lid retraction, lid lag and proptosis (Fig.16.11). These changes are also known as endocrine exophthalmos, dysthyroid ophthalmopathy, thyroid ophthalmopathy and ocular Graves’ disease (OGD).

Name the extraocular muscle most frequently affected in Graves’ ophthalmopathy.

Inferior rectus.

What is American Thyroid Association classification of Graves’ ophthalmopathy?

American Thyroid Association (ATA) has classified Graves’ ophthalmopathy irrespective of the hormonal status into the following classes; characterized by the acronym ‘NOSPECS’:

Class 0 : No signs and symptoms.

Class 1 : Only signs, no symptoms. Signs are limited to lid retraction with or without lid lag and mild proptosis.

Class 2 : Soft tissue involvement with signs of class 1 and symptoms including lacrimation, photophobia, lid or conjunctival swelling.

What are the two clinical types of Graves’ ophthalmopathy ?

1.Thyrotoxic exophthalmos (exophthalmic goitre): In this form, a mild exophthalmos is associated with lid signs and all signs of thyrotoxicosis which include: tachycardia, muscle tremors and raised basal metabolism

2.Thyrotropic exophthalmos (exophthalmic ophthalmoplegia): In it, marked exophthalmos and an infiltrative ophthalmoplegia is associated with euthyroidism or hypothyroidism.

What are the causes of pseudoproptosis ?

1.Buphthalmos

2.Lid retraction

3.High-axial myopia

4.Staphyloma

5.Enophthalmos of the opposite eye

What are the causes of reducible proptosis?

Early stages of ocular Graves’ disease

Haemangioma

Orbital varix

Caroticocavernous fistula

Which is the most common primary tumour of the orbit presenting as proptosis ?

Cavernous haemangioma

Name the most common primary orbital tumour of childhood.

Rhabdomyosarcoma

SQUINT AND NYSTAGMUS

A CASE OF SQUINT

CASE DESCRIPTION

Presenting symptoms. Patient presents with deviation of one eye which may be on medial side (convergent squint) or lateral side (divergent squint).

History of present illness must include following important points:

Age of onset

Mode of onset, sudden or gradual

Precipitating factors such as, systemic illness ocular cause, emotional breakdown, trauma

History of diplopia

Birth history is important in early childhood onset deviation.

History of use of glasses

Family history is also important in a case of strabismus.

Ocular examination should reveal:

Whether the manifest squint is convergent (Fig. 13.14) or divergent (Fig.13.15).

Abnormal head posture associated or not.

Whether the squint is unilateral or alternating

Ocular movements are normal (concomitant squint) or limited (paralytic or non-concomitant squint).

Angle of squint on corneal reflex test (Hirschberg’s test).

Note: Detailed orthoptic examination is not expected from an undergraduate student.

RELATED QUESTIONS

Name the various extraocular muscles.

Superior rectus

Inferior rectus

Medial rectus

Lateral rectus

Superior oblique

Inferior oblique

What is the origin of rectus muscles ?

The rectus muscles originate from a common tendinous ring (annulus of Zinn), which is attached at the apex of the orbit.

Where are the rectus muscles inserted ?

The rectus muscles are inserted into the sclera by flat tendons at different distances from the limbus as

What is the nerve supply of extraocular muscles?

The extraocular muscles are supplied by third, fourth and sixth cranial nerves. The third cranial nerve (oculomotor) supplies the superior, medial and inferior recti and inferior oblique muscles. The fourth cranial nerve (trochlear) supplies the superior oblique muscle, and sixth cranial nerve supplies the lateral rectus muscle.

What are the actions of extraocular muscles?

Action of each extraocular muscle is as below:

Describe uniocular movements of the eyeball.

Uniocular movements of the eyeball are called ductions. These are as follows:

1.Adduction.Itismedialrotationalongtheverticalaxis

2.Abduction. It is lateral rotation along the vertical axis

3.Infraduction. It is downward movement (depression) along the horizontal axis

4.Supraduction.It is upward movement (elevation) along the horizontal axis

5.Incycloduction (Intorsion). It is rotatory movement along the anteroposterior axis in which superior pole of cornea (12 O’ clock point) moves medially

6.Excycloduction (Extorsion). It is rotatory movement along the anteroposterior axis in which superior pole of cornea (12 O’clock point) moves laterally

What are version movements of the eyeball ?

Versions also known as conjugate movements, are synchronous (simultaneous) symmetric movements of both the eyes in the same direction. For example:

Dextroversion is the movement of both eyes to the right.

Levoversionisthemovementofbotheyestotheleft.

What are vergence movements of the eyeball?

Vergences, also called as disjugate movements, are synchronous and symmetric movements of both eyes in opposite directions, e.g.:

Convergence is simultaneous inward movement of both the eyes.

Divergence is simultaneous outward movement of both the eyes.

Define synergists, antagonists and yoke muscles.

1.Synergists are the muscles which have a similar primary action in the same eye, e.g., superior rectus and inferior oblique of the same eye act as synergistic elevators.

2.Antagonists are the muscles which have opposite actions in the same eye, e.g., superior and inferior recti are the antagonists to each other in the same eye.

3.Yoke muscles (contralateral synergists) are a pair of muscles (one from each eye) which contract simultaneously during version movements. Different pairs of yoke muscles are as follows:

Right medial rectus and left lateral rectus

Right lateral rectus and left medial rectus

Right superior rectus and left inferior oblique

Right inferior rectus and left superior oblique

Right superior oblique and left inferior rectus

Right inferior oblique and left superior rectus

What is Hering’s law of equal innervation?

According to it, an equal and simultaneous innervation flows from the brain to a pair of muscles which contract simultaneously (yoke muscles) in different binocular movements, e.g., during dextroversion, right lateral rectus muscles and left medial rectus muscles receive an equal and simultaneous flow of innervation.

What is Sherrington’s law of reciprocal innervation?

According to it, during ocular movements an increased flow of innervation to the contracting muscles is accompanied by a simultaneous decreased flow of innervation to the relaxing antagonists. For example, during dextroversion an increased innervational flow to the right lateral rectus and left medial rectus is accompanied by a decreased flow to the right medial rectus and left lateral rectus muscles.

What is the primary position of gaze?

It is the position assumed by the eyes when fixing a distant object (straight ahead) with the erect position of head.

What are the secondary positions of gaze?

These are the positions assumed by the eyes while looking straight up, down to the right and to the left.

What are the cardinal positions of gaze?

These are the positions which allow examination of each of the 12 extraocular muscles in their main field of action. There are six cardinal positions of gaze, viz. dextroversion, levoversion, dextroelevation, levoelevation, dextrodepression and levodepression.

What are the three grades of binocular single vision?

Grade 1. Simultaneous macular perception (SMP):

It is the power to see two dissimilar objects which can be superimposed to form a joint picture. For example, when the picture of a lion is projected onto the right eye and that of a cage to the left eye, an individual with presence of SMP will see the lion in the cage.

Grade II. Fusion: It consists of the power to superimpose two incomplete but similar images to form one complete image.

Grade III. Stereopsis: It consists of the ability to perceive the third dimension (depth perception).

What is squint; how do you classify it ?

Normally visual axes of the two eyes are parallel to each other in the primary position of gaze and this alignment is maintained in all positions.

A misalignment of the visual axes of the two eyes is called squint or strabismus. Broadly it can be classified as:

1.Apparent squint or pseudostrabismus

2.Latent squint (heterophoria)

3.Manifest squint (heterotropia), which includes:

i.Concomitant squint

ii.Incomitant squint.

What is heterophoria; what are its types ?

Also known as latent squint, it is a condition in which the tendency of the eyes to deviate is kept latent by fusion. Therefore, when the influence of fusion is removed the visual axis of one eye deviates.

Common types of heterophoria are:

1.Esophoria: It is a tendency to converge when binocularity is broken by any means

2.Exophoria: It is a tendency to diverge

3.Hyperphoria: It is a tendency to deviate upwards, while hypophoria is a tendency to deviate downwards. However, in practice it is customary to use the term right or left hyperphoria, depending on the eye which remains up as compared to the other.

Name a few tests by which heterophoria can be diagnosed.

1.Cover-uncover test

2.Maddox rod test

3.Maddox wing test

What is suppression ?

Suppression is a temporary active cortical inhibition of the image of an object formed on the retina of the squinting eye. This phenomenon occurs only during binocular vision (with both eyes open). It can be tested by Worth’s four-dot test.

What is abnormal retinal correspondence ?

Normally, fovea of the two eyes act as corresponding points and have the same visual direction (normal retinal correspondence). Sometimes in, a patient with squint, fovea of the normal eye and an extra foveal point on the retina of the squinting eye acquire a common visual direction, i.e., become the corresponding points. This adjustment is called abnormal retinal correspondence (ARC).

Name a few methods by which angle of squint can be measured.

1.Hirschberg’s corneal reflex test

2.Prism bar cover test (PBCT)

3.By synoptophore (major amblyoscope)

4.Krimsky’s corneal reflex test

5.Perimeter method

Describe Hirschberg’s corneal reflex test.

Hirschberg’s corneal reflex test is a rough but handy method to estimate the angle of manifest squint. In it, the patient is asked to fixate at a point light held at a distance of 33 cm and the deviation of the corneal light reflex from the centre of pupil is noted in the squinting eye. Roughly, the angle of squint is 15° and 45° when the corneal light reflex falls on the border of pupil and limbus, respectively.

What is a concomitant squint ?

Concomitant squint is a type of manifest squint in which the angle of deviation remains constant in all the directions of gaze; and there is no associated limitation of ocular movements.

How do you classify concomitant esotropia ?

1.Infantile esotropia

2.Accommodative esotropia

3.Non-accommodative esotropia

What is accommodative esotropia?

Accommodative esotropia occurs due to overaction of convergence associated with accommodation reflex. Refractive type of accommodative esotropia is associated with high hypermetropia (+4 to +7D).

How do you classify concomitant exotropia (divergent squint)?

1.Congenital exotropia

2.Primary exotropia

a.Intermittent

b.Constant

Unilateral

Alternating

3.Secondary (sensory deprivation) exotropia

4.Consecutive exotropia

What is paralytic squint ?

Paralytic squint is a type of incomitant squint in which ocular deviation results from complete or incomplete paralysis of one or more extraocular muscles.

What are the features of paralytic squint?

1.History of diplopia and confusion.

2.Secondary deviation is greater than primary deviation.

3.Ocular movements are restricted towards the action of paralyzed muscle.

4.Head is turned towards the action of paralyzed muscle.

What are the features of complete third cranial nerve palsy ?

These include the following (Fig.13.25):

1.Ptosis due to paralysis of levator muscle

2.Eyeball is deviated out and slightly down

3.Ocular movements are restricted in all the directions except outward

4.Pupil is fixed and dilated

5.Accommodation is completely lost

6.Crossed diplopia is elicited on raising the eyelid

What are the differences between paralytic and non-paralytic squint ?

What is nystagmus.

Nystagmus is defined as to-and-fro oscillatory movements of the eyes.

What are pendular and jerk nystagmus ?

In pendular nystagmus, movements are of equal velocity in each direction. In jerk nystagmus, the movements have a slow component in one direction and a fast component in the other direction. The direction of jerk nystagmus is defined by direction of the fast component.

What are clinical types of nystagmus ?

1.Physiological nystagmus, e.g., optokinetic nystagmus

2.Congenital nystagmus, e.g.,

Congenital jerk nystagmus

Latent nystagmus

Spasmus nutans

3.Acquired nystagmus, e.g.,

Acquired ocular nystagmus

Peripheral verstibular nystagmus

Central vestibular nystagmus

See-saw nystagmus

OCULAR INJURIES

A CASE OF BLUNT TRAUMA

CASE DESCRIPTION

Age and sex. Trauma to the eyeball may occur at any age in either sex. However, in general, ocular trauma is more common in children than adults and males than females.

Presenting symptoms and history. Patient usually presents with a direct blow to the eyeball by a large blunt object (tennis ball, cricket ball, fist etc) or injuries in a road side accident. There may be associated:

Visual loss

Pain and swelling of varying degree

Ocular examination may reveal varying signs depending upon the extent of trauma. In general the traumatic lesions produced by blunt trauma can be grouped as below:

Closed globe injury

Globe rupture

Extraocular lesions For details see page 403

RELATED QUESTIONS

What are the common sites for retention of an extraocular foreign body ?

Sulcus subtarsalis

Fornices

Bulbar conjunctiva

Cornea

How do you remove a corneal foreign body?

Eye is anaesthetized with topical instillation of 2 to 4 percent Xylocaine. X3

Lids are separated with universal eye speculum. X3

An attempt should be made to remove the foreign body with the help of a cotton swab stick. If it fails then foreign body spud or hypodermic needle should be used. X3

After removal of the foreign body, pad and bandage with antibiotic eye ointment is applied for 24 to 48 hours.