ABNORMAL SIZE
Small
Microcornea
Definition
- •
A very rare, congenital, unilateral or bilateral AD or AR condition that has many ocular and systemic syndromic associations ( Table 5.1 ).
Table 5.1
Associations of microcornea
- 1.
Ocular
- •
Cornea plana
- •
Corneal leukoma
- •
Iris abnormalities
- •
Microphakia
- •
Congenital cataract
- •
Glaucoma
- •
- 2.
Syndromic
- •
Turner
- •
Ehlers–Danlos
- •
Weill–Marchesani
- •
Waardenburg
- •
Nance–Horan
- •
Cornelia de Lange
- •
- 1.
Signs
- •
Adult horizontal corneal diameter is 10 mm or less ( Fig. 5.1 ).
Fig. 5.1
- •
Shallow anterior chamber.
- •
Other ocular dimensions are normal.
Nanophthalmos
Definition
- •
A rare, bilateral, congenital condition in which the globes have reduced volume but are otherwise grossly normal.
Signs
- •
Very high hypermetropia ( Fig. 5.2 ).
Fig. 5.2
- •
Adult corneal diameter is reduced but the lens has a normal volume.
- •
Short axial length averaging 18 mm.
- •
Shallow anterior chamber.
- •
Thick sclera.
- •
Fundus may show a crowded disc, vascular tortuosity and macular hypoplasia.
Late problems
- •
Angle-closure glaucoma.
- •
Uveal effusion characterised by choroidal detachment and retinal detachment ( Fig. 5.3 ).
Fig. 5.3
- •
Retinal detachment.
- •
Poorly tolerated intraocular surgery.
Microphthalmos
Definition
- •
An uncommon, unilateral or bilateral condition in which the axial length of the globe is reduced.
Types
- a.
Non-colobomatous (simple – Fig. 5.4 and Table 5.2 ).
Fig. 5.4
Table 5.2
Classification of non-colobomatous microphthalmos
- b.
Colobomatous ( Fig. 5.5 and Table 5.3 ).
Fig. 5.5
Table 5.3
Classification of colobomatous microphthalmos
- 1.
Isolated
- •
Sporadic
- •
Inherited (AD)
- •
- 2.
Syndromic associations
- •
Patau (trisomy 13)
- •
Edward (trisomy 18)
- •
Cat-eye (partial trisomy 22)
- •
Pagon (CHARGE)
- •
Meckel–Gruber
- •
Lenz microphthalmos
- •
Temple–Al Gazali
- •
Delleman
- •
Gorlin–Goltz
- •
- 1.
Large
Megalocornea
Definition
- •
A rare, congenital, bilateral, non-progressive usually XL-R condition that has many systemic associations ( Table 5.4 ).
Table 5.4
Systemic associations of megalocornea
- •
Marfan syndrome
- •
Apert syndrome
- •
Ehlers–Danlos syndrome
- •
Down syndrome
- •
Osteogenesis imperfecta
- •
Progressive facial hemiatrophy
- •
Renal carcinoma
- •
Mental retardation
- •
Signs
- •
Clear cornea with a horizontal diameter of 13 mm or more ( Fig. 5.6 ).
Fig. 5.6
- •
Very deep anterior chamber.
- •
Normal intraocular pressure.
- •
Pigment dispersion.
- •
High myopia and astigmatism but good visual acuity.
- •
Lens subluxation may occur as a result of zonular stretching.
Buphthalmos
Definition
An uncommon, usually bilateral, condition in which the globe is large due to increased intraocular pressure during the first 3 years of life. It has many ocular and systemic associations ( Table 5.5 ).
|
Signs
- •
Large cornea with variable oedema and scarring ( Fig. 5.7 ).
Fig. 5.7
- •
Very deep anterior chamber.
- •
Angle anomalies.
- •
Horizontal ruptures in Descemet membrane (Haab striae).
- •
Myopia.
- •
Optic disc cupping.
High myopia
Definition
- •
Refraction is greater than −6D and axial length is greater than 25 mm.
Signs
- •
Enlargement of the globe and cornea ( Fig. 5.8 ).
Fig. 5.8
- •
Chorioretinal degeneration and maculopathy.
- •
Predisposition to retinal detachment and glaucoma.
- •
Staphyloma.
Look for
- •
Stickler syndrome.
- •
Cohen syndrome.
- •
Marfan syndrome.
- •
Ehlers–Danlos syndrome.
- •
Fabry disease.
ABNORMAL SHAPE
Keratoconus
Definition
- •
A common, acquired condition which is bilateral in 85% of cases, although the severity of involvement may be asymmetric.
- •
It is associated with many ocular and systemic conditions ( Table 5.6 ).
Table 5.6
Associations of keratoconus
- 1.
Ocular
- •
Vernal disease
- •
Blue sclera
- •
Prominent corneal nerves
- •
Aniridia
- •
Ectopia lentis
- •
Retinitis pigmentosa
- •
Leber congenital amaurosis
- •
- 2.
Systemic
- •
Down syndrome
- •
Ehlers–Danlos syndrome type 6
- •
Marfan syndrome
- •
Apert syndrome
- •
Turner syndrome
- •
Atopic dermatitis
- •
Osteogenesis imperfecta type 1
- •
Mitral valve prolapse
- •
- 1.
Signs
- •
Central or paracentral stromal thinning with inferior apical protrusion ( Fig. 5.9 ).
Fig. 5.9
- •
Munson sign – bulging of the lower lid in downgaze ( Fig. 5.10A right eye; left eye is normal – Fig. 5.10B ).
Fig. 5.10A
Fig. 5.10B
- •
Vogt striae – fine deep vertical stromal stress lines which temporarily disappear on digital pressure ( Fig. 5.11 ).
Fig. 5.11
- •
Acute hydrops – corneal oedema resulting from tears in Descemet membrane ( Fig. 5.12 ).
Fig. 5.12
- •
Variable corneal scarring, depending on severity ( Fig. 5.13 ).
Fig. 5.13
Keratoglobus
Definition
- •
A very rare, bilateral, congenital condition.
Signs
- •
Mid-peripheral thinning, resulting in protrusion of the entire cornea ( Fig. 5.14 ).
Fig. 5.14
- •
Very deep anterior chamber.
- •
Acute hydrops in advanced cases.
Look for
- •
A syndrome comprising blue sclera, hyperextensible joints and dental abnormalities.
Pellucid marginal degeneration
Definition
- •
An uncommon, acquired, bilateral condition.
Signs
- •
High astigmatism.
- •
Inferior, crescent-shaped area of peripheral corneal thinning, 1–2 mm in width, extending from the 4 o’clock to 8 o’clock positions, which is separated from the limbus by normal cornea ( Fig. 5.15 ).
Fig. 5.15
- •
Protrusion located above the area of thinning.
Posterior keratoconus
Definition
- •
A very rare, usually unilateral developmental anomaly that bears no relationship to anterior keratoconus.
Signs
- a.
Generalis – increase in curvature of the entire posterior corneal surface.
- b.
Conscriptus – localised central posterior corneal indentation, often associated with opacification ( Fig. 5.16 ).
Fig. 5.16
Cornea plana
Definition
- •
A very rare bilateral, congenital condition which never occurs in isolation.
Signs
- •
Hypermetropia.
- •
Severe decrease in corneal curvature ( Fig. 5.17 ).
Fig. 5.17
- •
Shallow anterior chamber.
PERINATAL CLOUDING
Congenital glaucoma
Signs
- •
Unilateral or bilateral corneal oedema ( Fig. 5.18 ).
Fig. 5.18
Look for
- •
Buphthalmos.
- •
Ruptures in Descemet membrane (Haab striae) that may be horizontal or concentric with the limbus.
Birth trauma
Signs
- •
Linear usually vertical or oblique ruptures in Descemet membrane associated with oedema ( Fig. 5.19 ).
Fig. 5.19
Look for
- •
Forceps marks on the eyelids or cheeks.
Intrauterine rubella
Intrauterine rubella may cause corneal clouding as well as microphthalmos, cataract, anterior uveitis, retinitis and strabismus.
Sclerocornea
Definition
- •
A rare, congenital, usually bilateral but asymmetric condition.
Signs
- •
Opacification and vascularisation of the peripheral or entire cornea ( Fig. 5.20 ).
Fig. 5.20
- •
If only the peripheral cornea is involved, the resulting ‘scleralisation’ makes the cornea appear smaller than normal ( Fig. 5.21 ).
Fig. 5.21
Look for
- •
Peters anomaly (see next).
- •
Cornea plana.
Peters anomaly
Definition
- •
A usually bilateral, congenital condition that varies in severity.
Signs
- •
Central corneal opacities asymmetric in extent ( Fig. 5.22 ) and an underlying defect of the posterior stroma, Descemet membrane and endothelium.
Fig. 5.22
- •
May be associated with keratolenticular or iridocorneal adhesions best detected by ultrasonography ( Fig. 5.23 ).
Fig. 5.23
Congenital anterior staphyloma
Definition
- •
A very rare, congenital, usually unilateral condition.
Signs
- •
Opaque cornea lined posteriorly with uveal tissue that protrudes beyond the eyelids ( Fig. 5.24 ).
Fig. 5.24
- •
Keratectasia is identical except that it is not lined with uveal tissue.
Mucopolysaccharidoses
Mucopolysaccharidoses that occasionally may be associated with congenital corneal clouding include:
- a.
Hurler syndrome (MPS I-H) .
- b.
Scheie (MPS I-S) syndrome .
- c.
Morquio syndrome (MPS types IVA and IVB) .
- d.
Maroteaux–Lamy syndrome (types VIA and VIB) .
Signs
- •
Diffuse corneal clouding caused by fine punctate grey opacities ( Fig. 5.25 ).
Fig. 5.25
Mucolipidoses types II and IV
These are frequently associated with congenital corneal opacification.
Congenital hereditary endothelial dystrophy
Presentation
- •
At or soon after birth with bilateral symmetric diffuse corneal oedema.
Signs
- •
The appearance may vary from a blue-grey ground-glass appearance ( Fig. 5.26 ) to total opacification ( Fig. 5.27 ).
Fig. 5.26
Fig. 5.27
Congenital hereditary stromal dystrophy
Definition
- •
A very rare, non-progressive AD condition.
Signs
- •
Diffuse central haze composed of flaky-feathery opacities primarily involving the central anterior stroma.
PROMINENT NERVES
Signs
Causes
- •
See Table 5.7 .
Table 5.7
Causes of prominent nerve fibres
- 1.
Local
- •
Fuchs dystrophy
- •
Keratoconus
- •
Posterior polymorphous dystrophy
- •
- 2.
Systemic
- •
Primary amyloidosis
- •
Multiple endocrine neoplasia type II a and b
- •
NF1
- •
Refsum disease
- •
Leprosy
- •
Hereditary ichthyosis
- •
- 1.
EPITHELIAL MICROCYSTS AND VESICLES
Epithelial oedema
Signs
- •
Loss of normal corneal lustre ( Fig. 5.30 ) which may be associated with vesicles and bullae ( Fig. 5.31 ).
Fig. 5.30
Fig. 5.31
Meesmann dystrophy
Definition
- •
A very rare, innocuous AD condition.
Signs
- •
Myriads of tiny epithelial cysts most numerous in the interpalpebral region.
- •
The lesions appear grey in direct illumination ( Fig. 5.32 ) but clear on retroillumination.
Fig. 5.32
Cogan microcystic dystrophy
Definition
- •
A common condition which is frequently associated with bilateral spontaneous recurrent corneal erosion.
Signs
- •
Sparse microcysts, dots and fingerprint-like, or map-like epithelial lesions seen singly or in various combinations ( Fig. 5.33 ).
Fig. 5.33
OEDEMA
Corneal oedema is a common condition that may be caused by endothelial disease or severe elevation of intraocular pressure in an eye with a normal endothelium.
Iatrogenic endothelial damage
Cause
- •
Damage may occur during cataract surgery, particularly when associated with problems with lens implantation (pseudophakic bullous keratopathy – Fig. 5.34 ).
Fig. 5.34
Hydrops
Causes
Fuchs endothelial dystrophy
Definition
- •
An uncommon bilateral condition which usually occurs in old age.
Signs
- •
Starts as tiny central excrescences of Descemet membrane (cornea guttata – Fig. 5.36 ) which gradually become confluent.
Fig. 5.36
- •
Subsequent endothelial dysfunction results in stromal oedema and bullous keratopathy.
Acute angle-closure
Signs
- •
Corneal oedema.
- •
Severe elevation of intraocular pressure.
- •
Ciliary injection.
- •
Fixed dilated pupil.
- •
Shallow anterior chamber ( Fig. 5.37 ).
Fig. 5.37
- •
Closed angle on gonioscopy.
Disciform keratitis
Definition
- •
A unilateral condition associated with herpes simplex and occasionally herpes zoster.
Signs
- •
Oval area of stromal and epithelial oedema with underlying keratic precipitates ( Fig. 5.38 ).
Fig. 5.38
- •
Surrounding ring of stromal opacity (Wessely ring) may be seen in long-standing cases.
Acute postoperative endophthalmitis
Signs
- •
Endophthalmitis is frequently associated with corneal oedema ( Fig. 5.39 ).
Fig. 5.39
Look for
- •
Conjunctival injection and discharge.
- •
Fibrinous anterior uveitis and enlarging hypopyon.
- •
Impaired red reflex.
- •
Vitreous cells and debris.
Congenital hereditary endothelial dystrophy
PUNCTATE LESIONS
Punctate epithelial erosions (PEE)
Definition
- •
A common, non-specific, unilateral or bilateral, condition with many diverse causes.
Signs
- •
Tiny non-specific epithelial defects that stain with fluorescein ( Fig. 5.40 ) and rose Bengal.
Fig. 5.40
Causes
Maximal intensity of may indicate the probably aetiology as follows:
- a.
Superior – vernal disease, superior limbic keratoconjunctivitis, floppy eyelids, poorly fitting contact lenses, chlamydial infection and subtarsal foreign body.
- b.
Interpalpebral – dry eye, reduced corneal sensation and exposure to ultraviolet light.
- c.
Inferior – chronic blepharitis, lagophthalmos, trichiasis, rosacea, toxicity from drops and self-induced.
Superficial punctate keratitis (SPK)
Definition
- •
SPK is the hallmark of Thygeson disease which is an idiopathic usually bilateral condition that typically affects young adults.
Signs
- •
Coarse, distinct, granular, greyish, elevated epithelial lesions that may be associated with a mild subepithelial haze ( Fig. 5.41 ).
