what-when-how
In Depth Tutorials and Information
All three patients with OI and POAG were screened
for
MYOC
, a known genetic risk factor for glaucoma. No
mutations or sequence changes were found. It is pos-
sible that other genetic factors could be involved in these
patients with OI and POAG. Other animal studies have
suggested a role for collagen type I in POAG.
47-49
retinal detachment and its associated peripheral loss of
vision. RRDs generally require surgical treatment such as
scleral buckling surgery, vitrectomy or pneumatic retino-
pexy. With thin sclerae, OI eyes with RRD are likely best
treated by pneumatic retinopexy or vitrectomy as scleral
buckling would require securing bands or elements to
abnormally thin sclera that may have a higher risk for
complications such as scleral rupture. Madigan et al.
reported on retinal detachments in patients with OI.
54
Figure 31.4
demonstrates a retinal detachment in the
left eye of an OI type I patient who developed RRDs in
both eyes. This patient had an undetected inferior retinal
detachment in the left eye for many years and developed
a new retinal detachment in the right eye with symp-
toms of floaters and a veil covering his vision. Both eyes
required vitrectomy, intraocular laser and intraocular gas
for RRD repair.
Artificially Low Intraocular Pressures and OI
As eye or intraocular pressure (IOP) is a well-
recognized risk factor for glaucoma, accurate measure-
ment of eye pressure is essential for ophthalmologists
in assessing eye health and glaucoma risk. OI eyes with
very thin corneal thicknesses may have artifactually low
IOP.
50
Berggren et al. reported lower eye pressures in one
series of OI patients
51
while Evereklioglu et al. reported
lower eye pressures, thinner corneas and blue sclerae
in another series of OI patients compared to controls.
15
Visual field data were not part of these studies, glaucoma
was not formally diagnosed in these patients and these
artificially low pressures may have been a benign find-
ing in these OI patients. However, if OI eye pressures are
measured as artificially low with thin corneas, such OI
eyes may have higher IOP measurements than realized
due to this phenomenon with potentially increased risk
of developing glaucomatous optic nerve damage.
Choroidal Neovascularization
Choroidal neovascularization (CNV) describes the
abnormal growth of vessels from the choriocapillaris
through the Bruch membrane into the space beneath
the retinal pigment epithelium or the space beneath
the retina. If involving the central retina responsible for
visual acuity in the macula, choroidal neovascularization
can cause distortion of vision (metamorphopsia) which
affects central vision. CNV occurs in pathologic myopia,
angioid streaks, trauma and other causes of breaks in the
Bruch membrane. CNV also forms in the neovascular (or
“wet”) form of age-related macular degeneration. CNVs
have also been reported in eyes with OI. CNV formation
may result from weakening in the Bruch membrane that
may accompany OI and increase risk for development
of these abnormal vessels. Lepori reported on CNV in
OI (Lobstein's disease).
55
These abnormal CNV vessels
may respond to treatment with monoclonal antibod-
ies directed against vascular endothelial growth factor
(VEGF), which have found widespread use in manage-
ment of neovascular age-related macular degeneration.
Anti-VEGF antibodies have been reported in the treat-
ment of CNV in OI.
56
Vitreous and Retina Findings in OI
Vitreous and Retinal Hemorrhages
Reports of hemorrhages in OI eyes may be due to frag-
ile capillary walls, decreased ocular rigidity and scleral
thinning. Khalil described a case of subhyaloid hemor-
rhage in OI tarda between the retina and the posterior
surface of the vitreous.
52
Ganesh et al. further reported on
three cases of OI type I and intraocular hemorrhages after
minor trauma (short falls).
53
All three children described
had retinal hemorrhages and one also had vitreous hem-
orrhages. All also had subdural hematomas.
53
Rhegmatogenous Retinal Detachment
A rhegmatogenous retinal detachment is a separa-
tion of the retina from its attachment to the underlying
retinal pigment epithelium by means of fluid entry into
the subretinal space through a retinal tear. With known
decreased ocular rigidity, OI eyes may be more prone
to the transmission of forces into the eye from trauma
or eye movements and the subsequent development
of retinal tears and rhegmatogenous retinal detach-
ments (RRDs). Patients experience a sequence of symp-
toms often as a progression from seeing lashing lights
(photopsias), an increase in floaters and an expanding
curtain spreading from the peripheral vision towards
the center. They are sometimes slowly progressive and
undetected as one eye may compensate for the eye with
Macular Holes
Macular holes are full thickness openings in the ret-
ina at the center of the retina - the macula - and often
involve the foveal center, resulting in a loss of central
visual acuity. They are thought to form as a result of
anterior-posterior forces, tangential forces and weak-
ening in the retinal architecture that result in forming
openings in the macular center. They can be successfully
closed by retina specialists in ophthalmology with vitrec-
tomy surgery with intraocular gas or oil ill to maintain
closure of the macular hole. Benzimra reported treatment
of bilateral full thickness macular holes in a patient with
blue sclera secondary to OI.
57
