ABNORMALITIES OF SHAPE
Coloboma
Definition
- •
A rare, congenital, unilateral or bilateral, condition which may be associated with other defects.
Signs
- •
Notching of the inferior or inferotemporal equator with absent zonules ( Fig. 10.1 ).
Fig. 10.1
Look for
- •
Other colobomas and microphthalmos ( Fig. 10.2 ).
Fig. 10.2
- •
Ciliary body medulloepithelioma which may cause acquired notching of the lens.
Microphakia
Definition
- •
A small lens ( Fig. 10.3 ) that occurs in association with conditions that cause arrest of ocular development such as microphthalmos.
Fig. 10.3
- •
It may, however, be an isolated finding or associated with Lowe syndrome (see below).
Microspherophakia
Definition
- •
A rare, congenital, bilateral, condition that may be associated with a variety of other disorders ( Table 10.1 ).
Table 10.1
Associations of microspherophakia
- 1.
Systemic syndromes
- •
Weill–Marchesani
- •
Marfan
- •
- 2.
Miscellaneous
- •
AD familial
- •
Hyperlysinaemia
- •
Familial ectopia lentis et pupillae
- •
Peters anomaly
- •
Congenital rubella
- •
- 1.
Signs
- •
The lens has a small diameter and spherical shape, resulting in lenticular myopia ( Fig. 10.4 ).
Fig. 10.4
- •
Ectopia is usually downwards or into the anterior chamber.
Lentiglobus
Definition
- •
A very rare, congenital, usually unilateral, condition which causes induced myopia.
Signs
- •
A generalised hemispheric lens deformity which may be associated with posterior polar lens opacity.
Anterior lenticonus
Definition
- •
A rare, congenital, bilateral, condition which is associated with Alport syndrome which may be AD or X-LR.
Signs
- •
Localised anterior central conical projection ( Fig. 10.5 ) that may later be associated with opacification.
Fig. 10.5
- •
In early cases the red reflex shows an ‘oil-droplet’ sign ( Fig. 10.6 ) similar to that seen in keratoconus.
Fig. 10.6
Look for
- •
Posterior polymorphous corneal dystrophy.
- •
Flecked retina (see Figs 13.232 and 13.233 ).
- •
Progressive deafness and renal disease.
Posterior lenticonus
Definition
- •
A rare, congenital, bilateral, condition which may occur in isolation or in association with Lowe syndrome.
Signs
- •
Localised posterior conical projection of the lens ( Fig. 10.7 ).
Fig. 10.7
- •
Associated posterior with opacification is common ( Fig. 10.8 ).
Fig. 10.8
Look for
- •
Psychomotor retardation.
- •
Muscular hypotonia.
- •
Renal disease.
ECTOPIA LENTIS
Developmental
Ocular associations
- a.
Megalocornea .
- b.
Severe buphthalmos .
- c.
Very high myopia .
- d.
Aniridia ( Fig. 10.9 ).
Fig. 10.9
Hereditary causes without systemic manifestations
- a.
AD familial ectopia lentis .
- b.
AR ectopia lentis et pupillae in which pupil and lens are displaced in opposite directions (see Fig. 9.16 ).
- c.
Isolated familial microspherophakia .
Marfan syndrome
Definition
- •
An uncommon AD widespread disorder of connective tissue.
Signs
- •
Bilateral, symmetric, slowly progressive usually superotemporal subluxation with intact zonule ( Fig. 10.10 ) usually noted in childhood or early adult life.
Fig. 10.10
- •
Total dislocation into the vitreous ( Fig. 10.11 ) may occasionally occur in older patients.
Fig. 10.11
Look for
- •
Retinal detachment.
- •
Angle anomaly and glaucoma.
- •
Tall and thin stature with arm span > height.
- •
Arachnodactyly ( Fig. 10.12 ).
Fig. 10.12
- •
High-arched palate (see Fig. 15.38 ).
- •
Cardiovascular disease.
Weill–Marchesani syndrome
Definition
- •
A rare, usually AR, disease of connective tissue, conceptually the reverse of Marfan syndrome.
Signs
- •
Bilateral inferior subluxation may occur in late childhood or early adult life.
- •
Subluxation into the anterior chamber may also occur because the lens is small ( Fig. 10.13 ).
Fig. 10.13
Look for
- •
Short stature.
- •
Small, stubby toes ( Fig. 10.14 ) and fingers (brachydactyly).
Fig. 10.14
- •
Stiff joints.
- •
Mental handicap.
Homocystinuria
Definition
- •
A rare AR condition caused by an enzyme defect.
Signs
- •
Typically inferonasal subluxation with disintegration of the zonules ( Fig. 10.15 ) occurs in all patients by the age of 25 years.
Fig. 10.15
- •
Lens incarceration in the pupil (see Fig. 7.14 ) or total subluxation into the anterior chamber may also occur.
Look for
- •
Coarse fair hair and a malar flush ( Fig. 10.16 ).
Fig. 10.16
- •
Marfanoid habitus.
- •
Tendency to thromboses.
Other causes
- a.
Ehlers–Danlos syndrome type 6 (ocular sclerotic) is an AR connective tissue disorder in which ectopia lentis is uncommon.
- b.
Hyperlysinaemia is an AR inborn error of metabolism which is occasionally associated with ectopia lentis.
- c.
Stickler syndrome is an AD condition in which ectopia lentis is uncommon.
- d.
Sulfite oxidase deficiency is an AR disorder of sulphur metabolism in which ectopia lentis is universal.
Acquired
- a.
Blunt ocular trauma may cause subluxation and rarely dislocation into the anterior chamber.
- b.
Ciliary body melanoma may cause a slight shift of the lens as well as a localised opacity ( Fig. 10.17 ).
Fig. 10.17
- c.
Hypermaturity in which the cortex has liquefied and the hard nucleus sinks inferiorly ( Fig. 10.18 ); less frequently, the entire lens may be subluxated ( Fig. 10.19 ).
Fig. 10.18
Fig. 10.19
- d.
Degenerated eye ( Fig. 10.20 ).
Fig. 10.20
CHILDHOOD CATARACT
Morphology
Anterior polar
Inheritance
- •
Usually AD.
Signs
- •
The opacity may involve only the capsule ( Fig. 10.21 ).
Fig. 10.21
- •
It may be pyramidal and project into the anterior chamber ( Fig. 10.22 ).
Fig. 10.22
Look for
- •
Persistent pupillary membrane ( Fig. 10.23 ).
Fig. 10.23
- •
Anterior lenticonus.
- •
Peters anomaly.
- •
Microphthalmos.
- •
Aniridia.
Posterior polar
Signs
- •
The opacity that may involve only the capsule or it may form a plaque.
Look for
- •
Persistent hyaloid remnants (Mittendorf dot – Fig. 10.24 ).
Fig. 10.24
- •
Posterior lenticonus (see Fig. 10.8 ).
- •
Persistent anterior fetal vasculature.
Coronary (supranuclear)
Signs
- •
A deep cortical opacity that surrounds the nucleus like a crown ( Fig. 10.25 ).
Fig. 10.25
Lamellar
Inheritance
- •
Usually AD, occasionally AR.
Signs
- •
Round, central, shell-like opacity surrounding the nucleus ( Fig. 10.26 ).
