الفهرس 
Dermography
Diabetes MellitusOnly 14 pages are availabe for public view
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Abstract
RVO is the second mostcommon retinal vascular disease
after diabetic retinopathy.There are two types of retinal vein
occlusion (RVO): central retinal veinocclusion (CRVO) and
branch RVO (BRVO).Both CRVO and BRVO can be broadly
classified into ischaemic and non-ischaemic types based on the
area of capillary non-perfusion, and this distinction is useful for
clinical management.
Central retinal vein occlusion (CRVO) results from
thrombosis of the central retinal vein when it passes through the
lamina cribrosa. Branch retinal vein occlusion (BRVO) is caused
by venous thrombosis at an arteriovenous crossing.
Hypertension is a major risk factor for RVO. Other
associated risk factors include hyperlipidemia, smoking, history
of cardiovascular disease, Hyperhomocysteinaemia, Blood
coagulation disorders and glaucoma.
Thrombosis of the retinal veins causes an increase in retinal
capillary pressure resulting in increased capillary permeability
and leakage of fluid and blood into the retina . Co-existent retinal
ischaemia may exacerbate this process by the production of
vascular endothelial growth factor (VEGF) which in turn
promotes retinal capillary permeability resulting in further development of ME, and promote new vessel formation
principally but not exclusively involving the iris and angle in
CRVO and the retina in BRVO. These complications can lead to
neovascular glaucoma, vitreous haemorrhage and tractional
retinal detachment with severe visual impairment.
Patient usually suffers from visual loss whether gradual or
sudden, photophobia and may progress to blind painful eye
especially with ischemic forms of central retinal vein occlusion .
Full ophthalmic examination should be carried out. Fundus
examination show disc oedema, increased dilatation and
tortuosity of all retinal veins , widespread deep and superficial
haemorrhages, cotton wool spots, retinal oedema and capillary
non-perfusion in all four quadrants of the retina.
Optical coherence tomography is noninvasive investigation
for detecting macular edema even in the presence of hemorrhages,
Fundus fluorescein angiography which is done as soon as the
hemorrhages have cleared if the patient’s vision is still
depressed.Also some laboratory tests can be done to determine
the etiology as PT, aPTT, serum protein electrophoresis and
others.
The management of RVO involves a multidisciplinary
approachbetween the general physician and the ophthalmologist . The role of thegeneral physician is to manage any systemic risk
factors with the aimof reducing the risk of the patient developing
a further RVO or any nonoculartarget organ damage.
Intravitreal injection ofAnti- VEGFs as bevacizumab,
ranibizumab and Aflibercept is recommended for ME associated
withboth branch and central retinal vein occlusions withreduction
of CFT and improvement of VA, but the effects wear off and
reinjections are usually necessary to maintain improvements .
Corticosteroids can be used in RVO to reduce macular
edema, thereby, improves the visual acuity. The drugs used either
Intravitreal injection of triamcinolone acetonide ordexamethasone
intravitrealimplant. Wereassociated with cataract progression
andincreased IOP.
Grid laser photocoagulation is recommended for
treatmentof macular edema resulting from branchretinal -vein
occlusionafter 3–4 monthly injections of anti-VEGFand scatter
laser photocoagulationis used treatmentof neovascularization.
Several other potential surgical treatment including pars
plana vitrectomy, radial optic neurotomy, and laserinducedchorioretinal anastomosis which may improve visual
acuity in patient with non-perfused CRVO but may be associated
with significant ocular complication.