Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

A CASE OF ANTERIOR STAPHYLOMA

CASE SUMMARY

Presenting symptoms. Patient presents with loss of vision, bluish discoloration and bulging of the anterior part of the eye.

History is suggestive of symptoms of corneal ulceration (pain, redness, photophobia, watering, loss of vision and whitish discoloration) followed by the bluish discoloration and bulging of the anterior part of the eye.

Examination reveals that cornea is replaced by a lobulated ectatic scar tissue which is blackened due to the iris plastered behind it (Fig.5.21).

RELATED QUESTIONS

What is a staphyloma ?

Staphyloma refers to a localized bulging of weak and thin outer tunic of the eyeball (cornea or sclera) lined by uveal tissue which shines through the thinnedout fibrous coat.

What are the types of staphyloma?

1.Anterior staphyloma

2.Ciliary staphyloma

3.Intercalary staphyloma

4.Equatorial staphyloma

5.Posterior staphyloma

How is an anterior staphyloma formed?

In a patient with sloughing corneal ulcer when the whole cornea sloughs out, the inflamed iris is covered with exudates. Ultimately these exudates organize and form a fibrous layer over which the conjunctival or corneal epithelium rapidly grows and thus a pseudocornea is formed. Since the pseudocornea is thin and cannot withstand the intraocular pressure, it usually bulges forward along with the plastered iris tissue. This ectatic cicatrix is called anterior staphyloma.

What is the treatment of anterior staphyloma?

1.Most of the times there is no chance of getting useful vision in such eyes. Therefore, treatment is carried out to improve the cosmetic appearance.

Localized staphylectomy under heavy doses of steroids may be carried out. After healing, cosmetic artificial shell may be advised.

2.In patient where there is a chance of getting useful vision, keratoplasty (wherever possible) or keratoprosthesis may be performed.

What are the causes of posterior staphyloma?

Pathological myopia

Posterior scleritis

Perforating injuries

What is episcleritis ? Describe features of a nodule of episcleritis.

Episcleritis is a benign recurrent inflammation of the episclera, involving the overlying Tenon’s capsule but not the underlying sclera.

A typical nodule of episcleritis is flat, pink or purple, surrounded by injection and is usually situated 2 to 3 mm away from the limbus.

What is the differential diagnosis of nodular episcleritis?

Inflamed pinguecula

Foreign body embedded in the bulbar conjunctiva

Scleritis

DISEASES OF THE UVEAL TRACT

A CASE OF ACUTE IRIDOCYCLITIS

CASE DESCRIPTION

Presenting symptoms. A patient with acute iridocyclitis (anterior uveitis) presents with moderate to severe pain which radiates all over the distribution of trigeminal nerve, photophobia, watering, redness and some diminution of vision of sudden onset.

History of present illness. In addition to the details about the presenting symptoms, the history of present illness should also explore the following associations:

History of allergic conditions like bronchial asthma, hay fever, allergic rhinitis, allergic skin conditions

History of joint pains to rule out rheumatoid disease

History suggestive of urethritis

History of any dental problem

History of chronic rhinitis and/or sinusitis

History of trauma to eye

Past history should include enquiries about:

History of similar attacks in the past

History of chronic systemic infections such as tuberculosis, syphilis, leprosy, measles, mumps and any other infection

History of non-infectious systemic disorders such as diabetes, gout, rheumatoid arthritis and collagen disorder

History of allergic and autoimmune disorders

General physical and systemic examination should be conducted to rule out systemic diseases enumerated in the history. Special care should be given to dental, ENT, lymph nodes and joint examinations.

Ocular examination may reveal following signs (Fig.7.8):

Visual acuity is diminished.

Lids may show slight oedema.

Circumcorneal congestion is marked.

Cornea may be slightly hazy due to oedema and KPs at the back of cornea which are seen on slitlamp examination.

Anterior chamber shows aqueous cells and aqueous flare,hypopyon may also be present

Iris may show loss of normal pattern, muddy colour, posterior synechiae, iris nodules and patches of atrophy

Pupil is narrow, irregular and sluggishly reacting. Exudates may be present in pupillary area,occlusio pupillae and seclusio pupillae may be seen in some cases.

Lens. Pigment dispersal, exudates and iris adhesion may be seen on anterior capsule. Complicated cataract may also occur.

IOP may be normal, low or raised. It is raised firstly in hypertensive uveitis and secondly in pupillary block secondary glaucoma.

A CASE OF CHRONIC IRIDOCYCLITIS

CASE DESCRIPTION

Presenting symptoms are mild to moderate dull ache in the eye, mild photophobia and diminution of vision.

History of present illness and past history should explore the diseases mentioned in a case of acute iridocyclitis.

Ocular examination may reveal mild circumcorneal flush, keratic precipitates, aqueous flare, aqueous cells, iris atrophic patches, iris nodules, posterior synechial neovascularization and irregular pupil.

RELATED QUESTIONS

Define uveitis

Uveitis refers to inflammation of any part or whole of the uveal tract. Uveal tract includes iris, ciliary body and choroid.

How do you classify uveitis ?

I.Anatomical classification

1.Anterior uveitis (iridocyclitis)

2.Intermediate uveitis (pars planitis)

3.Posterior uveitis (choroiditis)

4.Panuveitis

II.Clinical classification

1.Acute uveitis

2.Chronic uveitis

III.Pathological classification

1.Suppurative or purulent uveitis

2.Non-suppurative uveitis, which may be:

(i)Non-granulomatous uveitis

(ii)Granulomatous uveitis

IV. Aetiological classssification (Duke-Elder’s)

1.Infective uveitis

2.Allergic uveitis

3.Toxic uveitis

4.Traumatic uveitis

5.Uveitis associated with non-infective systemic diseases

6.Idiopathic uveitis

What is the differential diagnosis of acute iridocyclitis?

Acute iridocyclitis must be differentiated from other causes of acute red eye; especially acute congestive glaucoma and acute conjunctivitis. The differentiating features are shown in Table 7.1.

What are the differences between granulomatous and non-granulomatous uveitis?

These are as shown in Table 7.2.

What are the common causes of acute anterior uveitis?

1.Microbial allergy, e.g., allergy to tubercular proteins, streptococcal proteins, spirochaetal proteins, etc.

2.Atopic uveitis

3.HLA associated uveitis, e.g., HLA-B27: Anterior uveitis is associated with ankylosing spondylitis and Reiter’s syndrome.

4.Idiopathic

What are the causes of granulomatous uveitis?

Tuberculosis

Syphilis

Sarcoidosis

Leprosy

Vogt-Koyanagi-Harada’s disease

Sympathetic ophthalmia

What are the common causes of unilateral iridocyclitis?

Traumatic uveitis

Herpes zoster uveitis

Fuchs’ heterochromic cyclitis

Retinal detachment

Haemophthalmitis

Iridocyclitis secondary to intraocular tumours

What are the keratic precipitates; what are their types and significance?

Keratic precipitates are proteinaceous-cellular deposits occurring at the back of cornea (Fig.7.9). These are of the following types:

1.Fine KPs are characteristic of Fuchs’ cyclitis and herpes zoster uveitis.

2.Small and medium size KPs are seen in acute and chronic non-granulomatous uveitis. These are composed of lymphocytes and may number in hundreds (usually 40-60).

3.Mutton fat KPs. These typically occur in granulomatous iridocyclitis and are composed of epithelioid cells and macrophages. They are large, thick, fluffy, lardaceous KPs, having a greasy or waxy appearance. They are usually few (10-15) in number.

What are iris nodules ?

Iris nodules typically occur in granulomatous uveitis. Nodules situated at pupillary border are known as Koeppe’s nodules, while those seen near the collarette are called Busacca’s nodules (Fig.7.12).

What are synechiae; describe their types?

Synechiae are adhesions of the iris with other intraocular structures. These can be divided into following types:

1.Anterior synechiae: These include anterior peripheral synechiae seen in the angle of anterior chamber and anterior central synechiae seen in adherent leucoma.

2.Posterior synechiae: These refer to adhesions of posterior surface of iris to the anterior surface of crystalline lens or intraocular lens implant or posterior capsule or anterior phase of the vitreous. These are of the following types:

Posterior segmental synechiae (Fig.7.8)

Annular synechiae (Fig.7.13), and

Total posterior synechiae (Fig.7.14).

What is seclusio pupillae and iris bombe ?

Annular or ring synechiae are 360° adhesions of pupillary margin to anterior capsule of the lens. These prevent the circulation of aqueous humour from posterior to anterior chamber (seclusio pupillae). Thus, the aqueous collects behind the iris and pushes it anteriorly (leading to iris bombe formation).

What is occlusio pupillae?

Occlusio pupillae refers to occlusion of pupil by the exudates.

What is festooned pupil?

When atropine is instilled in the presence of segmental posterior synechiae, the pupil does not dilate in the areas of synechiae, but dilates in the areas without synechiae. This results in an irregular and dilated pupil known as festooned pupil.

Name the various types of HLA associated uveitis.

HLA-B27 : Anterior uveitis seen with ankylosing spondylitis and Reiter’s syndrome

HLA-B5 : Behcet’s disease HLA-BW54: Glaucomatocyclitic crisis

HLA-BW22: Vogt-Koyanagi-Harada’s syndrome

What are the causes of diminution of vision in a patient with iridocyclitis?

One or more of the following factors cause diminution of vision:

Corneal oedema

Aqueous haze

Exudates in the pupillary area

Complicated cataract

Cyclitic membrane

Vitreous haze

Papillitis

Macular oedema

What are the complications of iridocyclitis?

Complicated cataract (Fig.7.15)

Secondary glaucoma

Cyclitic membrane

Cystoid macular oedema

Secondary periphlebitis retinae

Band-shaped keratopathy

Phthisis bulbi

What is the treatment of iridocyclitis?

I. Non-specific treatment

a)Local therapy

1.Mydriatic-cycloplegic drugs, e.g., 1 percent atropine, eyedrops or ointment; or percent homatropine eyedrops

2.Corticosteroid eyedrops such as dexamethasone eyedrops 4 times a day

b)Systemic therapy

1.Corticosteroids are quite useful in severe cases.

2.Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and phenylbutazone are used when steroids are contraindicated.

3.Immunosuppressive drugs are used in desperate and extremely serious cases.

4.Adrenocorticotropic hormone (ACTH) may be required in recalcitrant cases.

c)Physical measures

1.Hot fomentation. It is very soothing, diminishes pain and increases circulation.

2.Dark goggles give feeling of comfort by reducing photophobia.

II. Specific treatment

It consists of treatment of the cause when discovered, e.g., antitubercular drugs for the underlying Koch’s disease, adequate treatment of associated syphilis, toxoplasmosis, etc.

What are the features of Fuchs’ uveitis?

Fuchs’ uveitis is a chronic non-granulomatous type of low-grade anterior uveitis. It is unilateral and affects middle-aged persons. The disease is characterized by:

Heterochromia of iris

Fine KPs at the back of cornea

Faint aqueous flare

Absence of posterior synechiae

A fairly common rubeosis iridis

Comparatively early development of complicated cataract and secondary glaucoma

What are the features of glaucomatocyclitic crisis (Posner-Schlossman syndrome) ?

It typically affects young adults and is characterized by:

Recurrent attacks of acute rise of IOP (40-50 mm of Hg) without shallowing of anterior chamber

Fine KPs at the back of cornea without any posterior synechiae

Epithelial corneal oedema

A dilated pupil

A white eye (no congestion)

What is sympathetic ophthalmitis ?

Sympathetic ophthalmitis is rare bilateral granulomatous panuveitis which occurs following penetrating ocular trauma usually associated with incarceration of uveal tissue in the wound. The injured eye is called exciting eye and the fellow eye which also develops uveitis is called sympathizing eye.

What are Dalen-Fuchs’ nodules?

Dalen-Fuchs’ nodules are proliferation of the pigment epithelium of iris and ciliary body to form nodular aggregations in sympathetic ophthalmitis.

What is Behcet’s disease ?

Behcet’s disease is an idiopathic multisystem disease associated with HLA-B5. It is characterized by:

Recurrent acute iridocyclitis associated with hypopyon

Aphthous ulcerationGenital ulceration

Erythema multiforme

What are ocular lesions of sarcoidosis ?

1.Sarcoid plaque on the skin of the eyelids

2.Granulomatous infiltration of the lacrimal gland with xerosis

3.Conjunctival sarcoid nodules

4.Episcleritis

5.Iridocyclitis may occur as:

Acute iridocyclitis

Chronic granulomatous iridocyclitis (more common) with Koeppe’s and Busacca’s nodules on the iris and mutton fat KPs

Uveoparotid fever (Heerfordt’s syndrome)

6.Vitritis with snowball opacities

7.Choroidal and retinal granulomas

8.Secondary periphlebitis retinae with candle wax droppings

What is VKH Syndrome ?

Vogt-Koyanagi-Harada’s (VKH) syndrome is an idiopathic multisystem disorder associated with HLABW22. It is characterized by:

Cutaneous lesions such as: alopecia, poliosis and vitiligo

Neurological lesions include meningism, encephalopathy, tinnitus, vertigo and deafness

Ocular features are: chronic granulomatous anterior uveitis, posterior uveitis and exudative retinal detachment.

What is endophthalmitis? Enumerate common causes of purulent endophthalmitis.

Endophthalmitis is inflammation of the inner structures of the eyeball which include uveal tissue, retina and vitreous. Purulent endophthalmitis is a dreaded complication. Its common causes are:

1.Exogenous infections following:

Perforating injuries

Perforation of corneal ulcer

Intraocular operations such as cataract surgery and glaucoma surgery

2.Endogenous or metastatic endophthalmitis may occur rarely through blood stream from some septic focus in the body such as caries teeth, puerperal sepsis and generalized speticaemia.

What is panophthalmitis? Describe its treatment.

Panophthalmitis is an intense purulent inflammation of the whole eyeball including the Tenon’s capsule.

Since there is little hope of saving such an eye, evisceration operation should be performed to remove the pus and infected intraocular contents leaving behind the sclera.

Which is the most common presenting symptom in a patient with choroiditis ?

Floaters, i.e., moving small black spots in front of the eyes is the most common presenting symptom in a patient with choroiditis. Floaters occur due to pouring of exudates in the vitreous.

What are the symptoms of central choroiditis?

Defective vision

Floaters

Micropsia (patient complains of seeing the objects smaller than normal) due to separation of cones of macula due to oedema)

Metamorphopsia (patient perceives distorted images of the objects) results due to alteration in the retinal contour caused by a raised patch of choroiditis

Macropsia, i.e., perception of the objects larger than they are, may occur due to crowding together of cones

Photopsia, i.e., a subjective sensation of flashes of light may result due to irritation of cones by inflammatory oedema.

What is the most common cause of central choroiditis?

Toxoplasmosis.

What is pathognomonic feature of fungal endophthalmitis?

Flufy ball opacities in the vitreous are pathognomonic of fungal endophthalmitis.

At what stage vitrectomy operation should be performed in a patient with endophthalmitis?

Vitrectomy is the treatment of choice for fungal endophthalmitis. In bacterial endophthalmitis it should be performed when the condition does not improve with intensive conservative therapy for 48 hours.

What is Reiter’s syndrome ?

Reiter’s syndrome is characterized by a triad of urethritis, arthritis and conjunctivitis. In 20 to 30 per cent cases, acute non-granulomatous uveitis is also associated.

What are the causes of a patch of iris atrophy?

Senile

Post-inflammatory

Glaucomatous

Neurogenic, in lesions of ciliary ganglion

Essential iris atrophy

DISEASES OF THE LENS

A CASE OF SENILE CATARACT

CASE DESCRIPTION

Age and sex. It is seen equally in persons of either sex, usually above the age of 45 years (average 50-60 years).

Presenting symptoms. Patient usually presents with a gradual, painless and progressive loss of vision. In the early stages there may or may not be associated history of coloured haloes, uniocular polyopia, glare and misty vision.

History of present illness. In addition to the details about the presenting symptoms, the history of present illness should be taken:

To rule out other cause of acquired cataract e.g., history of exposure to radiations (radiation cataract) excessive heat in industrial workers especially in glass workers and iron workers (heat cataract), history of injury to the affected eye (traumatic cataract), history of diabetes mellitus (diabetic cataract), history of atopic diseases (atopic cataract),history of steroid intake (steroid cataract), history suggestive of anterior uveitis (complicated cataract) etc.

To rule out diseases affecting surgical treatment such as history of hypertension, diabetes mellitus, bronchial asthma.

Ocular signs observed in different types of senile cataract are shown in Table 8.1, page 179

General physical and systemic examination (see page 183)

Ocular examination. In addition to ocular examination to note signs of different types of cataract, the following useful information is essential before the patient is considered for surgery (see page 183):

Retinal function tests,

Search for local source of infection,

Slit-lamp examination for anterior segment status, and

IOP measurement.

RELATED QUESTIONS

What is your diagnosis?

Senile cataract (immature, mature, hypermature or nuclear, depending upon the type of cataract).

Define cataract.

Normal crystalline lens is a transparent structure. Any opacity in the lens or its capsule is called a cataract.

How do you classify cataracts ?

I.Aetiological classification

1. Congenital and developmental cataract

2.Acquired cataract

1.Senile cataract

2.Traumatic cataract

3.Complicated cataract

4.Metabolic cataract

5.Electric cataract

6.Radiational cataract

7.Toxic cataract, e.g.,

a)Corticosteroid-induced cataract

b)Miotics-induced cataract

c)Copper-and iron-induced cataracts (in chalcosis and siderosis respectively)

8.Cataract associated with skin diseases (dermatogenic cataract)

9.Cataract associated with osseous diseases

10.Cataract associated with miscellaneous syndromes e.g.,

Dystrophia myotonicaDown’s syndrome

II.Morphological classification (Fig.8.4)

1.Capsular cataract: It involves the capsule and may be:

a) Anterior capsular cataract b) Posterior capsular cataract

2.Cortical cataract: It involves the cortex of the lens

3.Nuclear cataract: It involves the nucleus of the crystalline lens

4.Polar cataract: It involves the capsule and superficial part of the cortex in the polar region and may be:

a) Anterior polar cataract b) Posterior polar cataract

What are the types of senile cataract ?

Cortical cataract

Nuclear cataract

Name the stages of maturation of senile cortical cataract.

Stage of lamellar separation

Stage of incipient cataract

Stage of immature senile cataract (cuneiform or cupuliform)

Stage of mature senile cataract

Stage of hypermature senile cataract (Morgagnian or sclerotic type)

What do you mean by nuclear sclerosis?

Nuclear siderosis is an aging process in which lens nucleus becomes inelastic and hard. Refractive index of the lens is increased resulting in myopia. These changes begin centrally and spread peripherally. On oblique illumination pupillary area looks greyish.

How will you differentiate immature senile cataract (ISC) from nuclear sclerosis without cataract changes?

See Table 8.3, Page 180

Name the complications which can occur during maturation of cortical cataract.

(a) Lens-induced glaucoma, which may be:

1.Phacomorphic glaucoma (secondary narrowangle glaucoma). It occurs due to intumescent (swollen) lens causing blockage of the angle of anterior chamber and pupil

2.Phacolytic glaucoma (secondary open-angle glaucoma). It occurs due to blockage of trabecular meshwork by macrophages laden with lens proteins leaked from the Morgagnian hypermature

cataract

(b)Phacoanaphylaxis

(c)Subluxation or dislocation of the lens.

What are the characteristics of diabetic cataract?

A true diabetic cataract is characterized by appearance of bilateral snowflake-like opacities hence the name ‘snowflake cataract’ or ‘snow-storm cataract’

What are the characteristics of a complicated cataract?

A typical complicated cataract is characterized by ‘bread-crumb’ appearance of the opacities situated in the posterior subcapsular area, which exhibit ‘polychromatic lustre’ on slit-lamp examination.

Enumerate the indications for extraction of a cataractous lens.

1.Grossly diminished vision hampering easy living

2.Medical indications, e.g.,

Lens-induced glaucoma

Phacoanaphylaxis

Patient having diabetic retinopathy or retinal detachment, treatment of which is hampered by the presence of lens opacities

3.Cosmetic indication. Some patients may insist for cataract extraction (even with no hope of getting useful vision) in order to obtain a black pupil.

What preoperative evaluation would you like to carry out before cataract surgery ?

1.General physical and systemic examination to rule out: diabetes mellitus, hypertension, obstructive lung disorders and any potential source of infection in the body such as septic gums, urinary tract infection, etc.

2.Ocular examination with special reference to:

1.Retinal function tests

2.Search for local source of infection, i.e., conjunctivitis, dacryocystitis, blepharitis, etc.

3.Intraocular pressure measurement.

Name the retinal function tests that you would like to carry out before planning cataract surgery?

1.Light perception (PL)

2.Projection of light rays (PR)

3.A test for Marcus Gunn pupillary response

4.Two-light discrimination test

What is the most accurate method of predicting the macular potential for visual acuity in the presence of advanced cataract?

Laser interferometry.

Name the objective tests for evaluating posterior segment of eye in a cataract patient.

1.Ultrasonography (A and B scan)

2.Electroretinography

3.Electro-oculography

4.Visually-evoked response

Surgical management of adulthood cataracts

For questions related to surgical management of cataract, see page 587

A CASE OF CONGENITAL/

DEVELOPMENTAL CATARACT

CASE DESCRIPTION

Age and sex. Congenital cataract is present since birth. Developmental cataract may occur any time from infancy to adolescence. It is equally common in both sexes.

Presenting symptoms. Parents may bring the child with one or more of the following complaints:

White reflex in the pupillary area (leukocoria)

Inability of the child to see well which may be noticed by the parents

Wandering movements of the eyes

Deviation (squint) in one eye

Nystagmus

History of present illness should include:

Details about the time of appearance and progress of the above symptoms

Obstetrical history to explore occurrence of rubella, malnutrition, diabetes mellitus, exposure to radiations and drug intake during pregnancy.

Birth history should include information about: home or hospital delivery; full-term or premature birth; normal or low birth weight (LBW) for age; history of birth trauma; and history of ocular infections after birth

Family history should include history of similar complaints in the family, history of any other ocular or systemic defects in the family, history of diabetes mellitus and history of consanguinous marriage.

General physical and systemic examination should be carried out thoroughly with special attention for any associated mental retardation, cerebral palsies, features of rubella, features of galactosaemia, hepatosplenomegaly and cardiovascular anomalies such as patent ductus arteriosus (PDA), ventricular septal defect (VSD) and pulmonary stenosis (PS).

Ocular examination. Conspicuous sign is leukocoria (white reflex in pupillary area). Make special note of visual acuity (if possible), any associated squint, nystagmus and other congenital anomalies such as microphthalmos, microcornea, aniridia, iris coloboma, and persistent pupillary membrane. Lens should be examined in detail after dilation of the pupil. If possible fundus should be examined to know the status of the posterior segment.

RELATED QUESTIONS

Name the types of congenital cataract.

Cataracta centralis pulverulenta (embryonic nuclear cataract)

Lamellar (zonular) cataract

Sutural cataract

Anterior polar cataract

Posterior polar cataract

Coronary cataract

Blue dot punctate cataract

Total congenital cataract

Enumerate the aetiological factors associated with congenital cataract.

1.Heredity (about 3 per cent cases)

2.Maternal factors, e.g.,

Malnutrition during pregnancy

Rubella infection

Toxoplasmosis

Cytomegalo inclusion disease

Drug ingestion during pregnancy, e.g., thalidomide, corticosteroids

3.Fetal or infantile factors, e.g.,

Anoxia due to placental haemorrhage

Metabolic disorders, e.g., galactosaemia, neonatal hypoglycaemia

Lowe’s syndrome

Myotonia dystrophica

Birth trauma

Malnutrition in early infancy

4.Idiopathic (about 50 per cent cases)

What are the features of zonular (lamellar) cataract?

Zonular cataract typically occurs in a zone of fetal nucleus surrounding the embryonic nucleus (Fig. 8.5). The area of the lens internal and external to the zone of cataract is clear, except for small linear opacities like spokes of a wheel (riders) which run outwards towards the equator. It is usually bilateral and frequently causes severe visual defect.

What is the differential diagnosis of a white pupillary reflex?

1.Congenital cataract

2.Retinoblastoma

3.Retinopathy of prematurity (retrolental fibroplasia)

4.Persistent hyperplastic primary vitreous

5.Parasitic endophthalmitis

6.Exudative retinopathy of Coats

How will you manage a case of congenital cataract?

1.Small stationary lens opacities which do not interfere with vision can safely be ignored

2.Incomplete central stationary cataracts may be treated by optical iridectomy or use of mydriatics to improve the vision considerably

3.Complete cataracts should be removed surgically as early as possible

Name the surgical procedures in vogue for management of childhood cataracts

1.Discission (needling) operation (almost obsolete)

2.Anterior capsulotomy and irrigation aspiration of the lens matter

3.Lensectomy

How should paediatric aphakia be corrected?

1.Children above the age of 5 years can be corrected by implantation of posterior chamber intraocular lens during surgery

2.Those below the age of 5 years should preferably be treated by extended wear contact lens. Spectacles can be prescribed in bilateral cases. At a later stage secondary IOL implantation may be considered

3.Epikeratophakia and keratophakia are still under trial

A CASE OF APHAKIA

CASE DESCRIPTION

Presenting symptoms. Patient usually gives history of cataract extraction operation (postoperative aphakia). Sometimes patient may present with such a situation following trauma to the eye (aphakia due to traumatic posterior dislocation of lens) and rarely without any cause (aphakia due to spontaneous posterior dislocation of lens).

Patient usually has marked loss of vision both for distance and near due to high hypermetropia and absence of accommodation, respectively.

Patient may complain of seeing red (erythropsia) and blue (cyanopsia) images. This occurs due to excessive entering of ultraviolet and infra red

rays in the absence of crystalline lens. Signs of aphakia seen on ocular examination:

Limbal scar may be seen in surgical aphakia

Anterior chamber is deeper than normal

Iridodonesis, i.e., tremulousness of the iris can be demonstrated

Pupil is jet black in colour

Purkinge image test shows only two images (normally four images are seen)

Fundus examination shows hypermetropic small disc

Retinoscopy reveals high hypermetropia

A CASE OF PSEUDOPHAKIA

CASE DESCRIPTION

Presenting symptoms

Patient usually gives a history of cataract operation and may also be aware of the intraocular lens (IOL) implantation.

Patient may give history of normal far vision (emmetropia produced by IOL) but defective near vision due to loss of accommodation.

Some patients may give history of normal near vision but defective far vision (due to 2-3 D myopia produced by a high power IOL).

Some patients are uncomfortable due to defective vision both for distance and near. This occurs due to hypermetropia produced by a low power IOL and loss of accommodation.

Signs of pseudophakia

Surgical limbal scar may be seen

Anterior chamber is slightly deeper than normal

When implanted, the angle supported anterior chamber IOL (Fig.8.23) and iris claw IOL (Fig.8.25) are seen in the anterior chamber.

Mild iridodonesis (tremulousness of iris) may be demonstrated

Purkinge image test shows four images

Pupil is blackish in colour. When light is thrown in pupillary area, shining reflexes are observed. When examined under magnification after dilating the pupil, the presence of posterior chamber IOL when implanted is confirmed (Fig.8.26)

Visual status and refraction of the patient will vary depending upon the power of IOL implanted as described above.

RELATED QUESTIONS

Define aphakia

Aphakia literally means absence of the crystalline lens from the eye. However, from the optical point of view, it may be considered as a condition in which the lens is absent from the pupillary area and does not take part in refraction. Optically aphakia may be:

Complete aphakia i.e, whole of the lens is absent from its normal position.

Partial aphakia, i.e., part of the lens is present in the pupillary area. In this situation aphakic and phakic portions are seen simultaneously in pupillary area.

Enumerate the refractive changes which occur in an aphakic eye.

1.Eye becomes highly hypermetropic.

2.Total power of the eye is reduced to +44 DS from +60 DS.

3.Anterior focal distance becomes 23 mm (from 15

mmin normal phakic eye).

4.Posterior focal distance becomes 31 mm (from 24

mmin normal phakic eye).

5.There is anterior shift of nodal point and principal focus.

6.There is complete loss of accommodation due to absence of lens.

7.Astigmatism is induced due to corneal/limbal scar.

Name the various modalities for correction of aphakia and enumerate advantages and disadvantages of each.

1. Spectacles

Advantages: It is cheap, easy and safe method of correcting aphakia.

Disadvantages: (i) Image is magnified by 30 per cent, so not useful in unilateral aphakia (produces diplopia), (ii) problems of spherical and chromatic aberrations may be troublesome, (iii) field of vision is limited, (iv) prismatic effect of thick glasses causes, ‘roving ring scotoma’ (v) cosmetic blemish, especially in young aphakics.

2. Contact lenses

Advantages: (i) Less magnification (5%) of the image, (ii) elimination of aberrations and prismatic effect of thick glasses, (iii) wider and better field of vision, (iv) cosmetically better accepted by young persons.

Disadvantages: (i) more cost, (ii) cumbersome to wear, especially in old age and in childhood, (iii) corneal complications may occur.

3. Intraocular lens implantation

It is the best available method of treatment. Advantage: It offers all the advantages which the contact lenses offer over the spectacles. In addition, the disadvantages of contact lenses are also taken care of.

Disadvantages: It requires more skilled surgeons and costly equipment.

4. Refractive corneal surgery

It is still under trial and includes keratophakia and epikeratophakia.

What are fundus findings in a patient with high hypermetropia?

Fundus examination in a patient with high hypermetropia may show:

Pseudopapillitis

Shot silk appearance of the retina

Enumerate the signs of aphakia.

Deep anterior chamber

Iridodonesis

Jet black pupil

Purkinje’s image test shows only two images (normally four)

Fundus examination shows small optic disc.

Retinoscopy, reveals high hypermetropia.

What is the average standard power of the lenses required for spectacle correction of aphakia ?

In preoperative emmetropic patient, the standard power of the lenses required for spectacle correction of aphakia for distance vision is + IODS with an additional cylindrical lens for acquired astigmatism. For near vision correction an additional +3DS is required as the accommodation is absent in an aphakic eye.

What is pseudophakia?

Pseudophakia refers to presence of an intraocular lens in the pupillary area.

What is the refractive position of the pseudophakic eye ?

A pseudophakic eye may be emmetropic, myopic or hypermetropic depending upon the power of the IOL implanted.

What is the average standard power of the posterior chamber IOL ?

Exact power of an IOL to be implanted varies from individual to individual and is calculated by biometry using keratometer and A-scan ultrasound.

What is the average weight of an IOL?

Average weight of an IOL in air is 15 mg and in aqueous humour is about 5 mg.

What is the power of the IOL in air vis-a-vis in the aqueous humour?

Power of an IOL in air is much more (about +60D) than that in the aqueous humour (about + 20D).