D/D OF CORNEAL LESIONS:

D/D OF CORNEAL LESIONS:

The cornea provides a variety of signs for the slit-lamp examination. These signs are easy to detect provided you examine each layer in turn and know how to use the various slit-lamp techniques. Usually more than one sign is present in the cornea. The following provide lists of differential diagnosis of common corneal signs seen in the examination.

Ferritin lines
(This seldom occurs in isolation in the examination. It is either a coincidental finding or associated with the corneal problem.)

· Hudson-Stahli's line (occurs in elderly and is found at the junction between the upper 2/3 and lower 1/3 of the cornea)

· Ferry's line (found anterior to a filtering bleb)

· Stocker's line ( found anterior to a pterygium)

· Fleischer's ring ( found at the base of keratoconus)

· foreign body (Rust ring).

· others ( diseases which distort the surface of the cornea as recurrent erosion syndrome, radial keratotomy)

Vortex keratopathy
(Also known as cornea verticillata; it is characterized by epithelial deposition which is arranged in a vortex fashion and usually begins just below the pupil and radiate outward. Like ferritin lines it is unlikely to be the only signs, if there is no other physical signs in the cornea ask to examine the posterior segment. For example, you may be given vortex keratopathy with tamoxifen deposition in the macula or vortex keratopathy with bull-eye maculopathy due to chloroquine toxicity.)

· Fabry's disease

· Drug-induced

amiodarone
chloroquine/hydroxychloroquine
tamoxifen
chlorpomazine
indomethacin

Keratoconus:

Marfan

Ehler danlos

Down Syndrom

Turner Syndrom

RP

Leber’s amourosis

Atopic eye disease

Contact lens use

Aniridia

Corneal neovascularization
(These may be superficial or deep in stroma. In the examination, the most common cases are phthisical eye, trauma, herpes simplex keratopathy, chemical burn and ocular cicatricial pemphigoid.)

· Trauma:

alkali burns

contact lens wear

· Infections

bacteria such as chlamydia, staphylococcus, pseudomonas
viruses such as herpes simplex and herpes zoster
protozoa such as onchocerca volvulus, leishmania brasiliensis

· Immunologic diseases

Steven-Johnson's syndrome
graft rejection
cicatricial ocular pemphigoid

Mooren’s ulcer

· Degenerative disorders

Pterygium
Terrien's marginal degeneration

Band keratopathy
(It is found in the palpebral fissure. Although it may occur singly, in the examination you are likely to be given one with underlying ocular diseases for example chronic uveitis, interstitial keratic, phthsical eye or silicone oil in the anterior chamber)

· Ocular causes

Chronic uveitis esp in paediatrics
interstitial keratitis
phthsical eye
Silicone oil in the AC

· Systemic disease

hypercalcaemia /hyperphosphatemia

hyperuricemia

Hereditary-dystrophic band keratopathy

Idiopathic- in eldery

Ghost vessels (Interstititial keratitis)
(These usually occur in deep stroma in patients with interstitial keratitis. The chronic inflammation usually leaves a thin cornea and possibly anterior or posterior synechiae. Although interstitial keratitis classically occurs in congenital syphilis in which case the condition is invariably bilateral, it can also occur in a variety of infection. The most likely case in the examination is congenital syphilis and the patient may have the typical facial features of saddle nose, deafness and Hutchinson's teeth or may be normal. Avoid using words like syphilis (in front of the patient) when asked about the diagnosis or investigation instead used terms like St. Louis's disease or serology for Treponema pallidum).

· Bacterial disease

congenital syphilis
tuberculosis
leprosy

· Viral disease

herpes simplex
herpes zoster
measles
mumps
rubella

· Parasitic disease

leishmaniasis
onchocerciasis
cysticerosis

· Unknown aetiology

Cogan's syndrome

Breaks in Descemet's membrane
(This is a common sign in the examination and the most common cause in the examination is bulphthalmos. Therefore, look out for differences in corneal size. )

Advanced keratoconus (Vogt).

Congenital glaucoma: curvilinear or Horizontal rupture (Haab)

Trauma (for example forcep delivery); vertical or oblique

Peripheral corneal thinning:
(In the clinical examination, the most common cases will include rheumatoid arthritis, Mooren's ulcer and Terrein's marginal degeneration. However, in your differential diagnosis do not forget to mention more common condition such as bacterial infection or recurrent marginal keratitis.)

Local causes:

Any where

dellen

marginal keratitis
phylyctenulosis
Mooren's ulcer

vernal keratoconjunctivitis …

Superior

superior limbic keratoconjunctivitis

Terrien's marginal degeneration

Furrow degeneration…

Inferior

atopic dermatits

neurotropic/exposure

dry eye

pellucid marginal degeneration

Collagen vascular diseases

rheumatoid arthritis
systemic lupus erythematosus
relapsing polychondritis
Wegener's granulomatosis

Dermatologic conditions= acne rosacea

Inflammatory bowel diseases

Blood disorders= leukaemia

Corneal oedema
(Another common sign in the examination. The sign may be missed if subtle unless you look at the corneal thickness and the present of clear spaces in the stroma. You must look for the underlying cause. The most common case ispseudophakic bullous keratopathy.)

· Acute increase in IOP

acute glaucoma- epithelial edema

Endothelium decompensation- stromal edema

inherited

congenital hereditary endothelial dystrophy
posterior polymorphous dystrophy
Fuch's dystrophy

trauma
post-operative: PBK√√

mechanichal trauma

instruments

IOL esp during periods of AC shallowness esp after the wash of VES

US- AC phaco

Toxicity (TASS): limbal – limbal edema + dilated fixed pupil + severe glaucoma

DM detachment

blunt blades

IOL insertion through a small wound

infectious
corneal ulcer
endopthalmitis

inflammation

chronic uveitis

graft rejection

others-

chronic rise in IOP- chronic glaucomas

ICE

DM rupture:

advanced keratoconus

congenital glaucoma

trauma (for example forcep delivery)

Cloudy cornea in a child: STUMPED

S= Sclerocornea

T= Trauma: Birth

U=

M= Metabolic: cystinosis/MPS

P= Peters Anomly

E=

D= Dystrophy: CHED/CHSD/PPD

Buphtalmos

Pigments on the endothelium
(The typical case in the examination is Krukenberg's spindle in patient with pigment dispersion syndrome. However, pigments can also occur in various conditions and a detailed examination of the anterior segment may provide the clues.)

pigment dispersion syndrome

pseudoexfoliation syndrome

post-cataract surgery

previous corneal performation in which the iris was incarcerated in the wound

trauma

iris melanoma

idiopathic

Keratic precipitates in the endothelium
(The most common case is Fuch's heterochormic cyclitis in which there are multiple discrete KP evenly distributed in the endothelium. Occasionally you may be given a patient with mutton fat KP and asked to give a differential diagnosis. Possible cases include sarcoidosis (look for nodules on the iris), toxoplasmosis (there may be chorioretinitis scar in the posterior segment) and rarely sympathetic ophthalmia (look for signs of ocular damage in the opposite eye)

Dendritc epithelial lesion:

HSV

HZV

Acanthamoeba

CL

Healing abrasion

Prominent corneal nerves (D/D: ghost vessels & Lattice dystrophy)

· Corneal dystrophies (Fuchs’, keratoconus)

· NF I

· Buphthalmos

· leprosy

· Ichthyosis

· After corneal grafts

· Multiple endocrine neoplasia.

· Refsum disease

· trauma

Filamentary keratitis:

· dry eye

· Exposure keratopathy

· Neuroparalytic keratitis

· Recurrent erosions

· prolonged patching

· SLK

· Midbrain strokes

· Blepharospasm

· HZV

Pigment Epithelial Erosions (PEE):

Superior: Spring catarrh/SLK/floppy lid/poor CL fitting

Middle: dry eye/ NP keratitis/ UV (welding arc).

Inferior: lid margin dis/ rosacea/ exposure/ toxicity

Kayser Fleisher ring:

Wilson’s diseases

Primary biliary cirrhosis

Chronic active hepatitis

Multiple myeloma