Rare type of corneal abnormality

1. Dr. K. Vasantha M.S.,F.R.C.S
Director RIO Chennai Rtd

2.  Non inflammatory, non progressive ectasia of the
posterior surface of the cornea
 Rare
 May be associated with opacification of the cornea
 Usually congenital
 Mostly unilateral
 Familial incidences reported

3.  Keratoconus posticus generalis- the cornea will be clear.
Hence difficult to diagnose. Pachymetry will be needed
to diagnose and to assess the amount of defect
 Keratoconus posticus circumspectus is of two types.
Either central or paracentral
 In this type opacity is common. Pigment deposits also
will be seen.
 Visible with retro illumination
 UBM and AS-OCT will confirm the diagnosis

4.  ? Cleavage abnormality
 ? Mild form of Peters anomaly
 The presence of anterior lens abnormalities suggest
delayed separation of surface ectoderm from lens
epithelium
 Pigments on the back suggest delayed separation of the
iris epithelium

5.  ? Mesenchymal dysgenesis
 Delayed separation causing defects in migration of
mesenchyme in to the a.c
 So development of the endothelium is affected causing
defective development of the stroma
 In familial cases systemic associations are seen. But no
genetic associations have been noted

6.  Anterior lenticonus
 Anterior polar cataract
 Congenital cataract
 Indentation of the anterior surface of the lens
 Optic nerve coloboma, tilted disc
 Macular scarring

7.  Extra ocular – ptosis, proptosis, hypertelorism, squint
 Anterior chamber may be shallow
 Iris – Synechiae, atrophy, iridoschisis, coloboma
 Systemic- waddling gait, barrel chest, webbed neck
 Maxillary hypoplasia, large head, cleft palate,
preauricular pit, deafness
 Short arms
 Hypothyroid, amenorrhea, absence of uterus
 Mental retardation

8. Keratoglobus Posterior keratoconus
 Rare
 Bilateral
 Thinning is more in the
periphery
 Generalized protrusion
 Mild or no scar
 Striae very rare
 Very rare
 Usually unilateral
 Paracentral and posterior
 No protrusion
 Scarring is common
 No striae

9.  This condition is usually bilateral
 Begins after the age of 20
 There is an inferior band of thinning
 The bulge is above the band of thinning
 Scarring is rare (only if hydrops occur)
 Stromal striae may be seen

10.  Any refractive error if present must be corrected.
 Prevent amblyopia
 For a localized opacity rotation graft can be done
 If it is too large penetrating keratoplasty
 It must be remembered that IOL power calculation is
difficult in these cases as corneal power will be over
estimated

11.  Rarely thinning can occur following injury or infection
 Will be unilateral