what-when-how
In Depth Tutorials and Information
overlapping features of Ehlers-Danlos syndrome,
another collagen synthesis connective tissue disorder.
33
The abnormalities found are called Reiger's anomaly
(RA) and represent a constellation of anterior segment
dysgenesis findings including iris atrophy, a promi-
nent Schwalbe's line, polycoria (extra holes in the iris),
corectopia (abnormal location of the pupil) and iris-
corneal adhesions (peripheral anterior synechiae).
Eyes with Reiger's anomaly often develop severe glau-
coma. This 19-year-old male OI patient had no frac-
tures at birth but multiple fractures in early childhood,
decreased vision in the left eye at 5 years of age and pain-
ful decreased vision in the right eye at 7 years of age. On
exam, he had proptotic eyes, bilateral corneal epithelial
edema, bilateral blue sclerae, iris atrophy in both eyes and
corectopia, polycoria and peripheral anterior synechiae in
the left eye. He did not have dentinogenesis imperfecta
but did have pectus excavatum, thoracic scoliosis, lax-
ity and malformation of distal interphalangeal and hip
joints along with diffuse osteoporosis, partial collapse of
the T10 vertebral body, left tibial fracture, mitral valve
prolapse and mild hearing loss at 800 Hz in the left ear.
A deletion of nucleotide A at the
COL1A1
cDNA position
c3313 (c.3313delA) leading to a frameshift and premature
stop codon downstream (p.Arg1105GlufsX3) was found
by genetic analysis. The abnormal mRNA was predicted
to undergo nonsense mRNA decay. High-resolution
karyotype analysis showed normal 46 XY chromosomal
constitution at the 500 band stage without large dele-
tions, translocations or other rearrangements. Although
microdeletions or inversions were not screened for in this
patient in the
PAX6
,
PTX2
or
FOXC1
sites known to be
associated with Reiger's anomaly, this patient's Reiger's
anomaly may have been related to OI.
Other anterior segment anomalies in OI have also
been reported, including abnormalities in the iridocor-
neal angle in three families with OI (Lobstein's disease).
34
eye findings over time in the general population and
may also occur in patients with OI, although the preva-
lence of cataracts in OI patients is unknown.
28
Presbyopia
A decrease in the ability of the lens to change shape
and refractive power for accommodation for near
vision is called presbyopia. It is often treated with read-
ing glasses. This condition occurs in most people with
increasing age and may also be found in OI patients,
although the prevalence and onset of presbyopia in OI
patients is unknown.
Sclera Findings in OI
Progressive Myopia
Eyes may become increasingly near sighted - myopic -
from axial length elongation. This is known as pro-
gressive myopia. This condition may especially also
occur in highly myopic patients who develop posterior
staphylomas, abnormal degenerative expansions of the
scleral wall from thinning and ectasia possibly second-
ary to collagen bundle thinning and degeneration.
36
Scott et al. described a case of progressive myopia from
posterior staphyloma in a 40-year-old woman with OI
type I and blue sclerae who had a first degree relative
with known OI type I and
COL1A1
and
COL1A2
muta-
tions.
37
The patient experienced a refractive change
from −2.25/−3.50 × 175 to −4.00/−5.00 × 177 over 6
months in the left eye while the right eye was stable at
−2.50/−4.50 × 178 with a normal visual acuity of 20/20
(0.00 Log Mar - 6/6) in both eyes. Testing with opti-
cal coherence tomography and B-scan ultrasonography
confirmed the staphyloma in the left eye. The staphy-
loma was thought to be related to reduced ocular rigid-
ity seen in OI that may have encouraged its formation.
The authors advised looking for posterior staphyloma
in cases of progressive myopia and visual loss in OI
patients along with lenticular myopia and keratoconus.
Lens Findings in OI
Ectopia Lentis
Ectopia lentis is the partial dislocation of the lens
found in many connective tissue disorders. The condi-
tion may eventually progress to complete dislocation of
the lens from its proper location due to loss of zonular
support. It has been documented in many connective tis-
sue disorders including OI.
35
Blue Sclerae and Decreased Ocular Rigidity
The finding of blue sclerae is common in some OI
patients with variable severity. Different theories for the
cause of blue sclerae in OI include (1) decreased thick-
ness and increased transparency of the scleral wall due
to altered collagen fiber composition and fiber alignment
as described by histopathology studies;
11
(2) decreased
light scattering by the sclera
38
and (3) increased visibility
of the underlying choroid and melanocytes beyond the
scleral external surface.
Table 31.1
summarizes how different types of OI vary
in their degree of blue sclerae. Findings in OI with muta-
tions in the
COL1A1
or
COL1A2
genes range from per-
sistently blue sclerae in OI type I to dark blue sclera in
Cataract
A lens with clouding is called a cataract. Cataracts
may occur from the natural opacification of lens fibers
over time or after eye trauma that damages the lens.
Cataracts may cause poor focus of light onto the retina
and subsequently blurry vision. Cataracts are common
