Gradual loss of vision Flashcards
causes of gradual loss of vision
cataract, macular degeneration, glaucoma, diabetic retinopathy, hypertension, optic atrophy, slow retinal detachment
what is the main cause of blindness
age related macular degeneration
what part of the vision is lost in age related macular degeneration
central vision (peripheral is maintained)
dry age related macular degeneration
mainly drusen and degenerative changes at macula. slow progression
wet age related macular degeneration
new vessels grow from choroid into retina and leak. deteriorates quickly
features age related macular degeneration
progressive gradual loss of central vision- difficulty reading and recognising distant objects. peripheral vision maintained so can navigate. pupil reactions normal
what can wet age related macular degeneration present like
vision deteriorates quickly. distorted images- straight lines wavy.
when are drusen usually first deposited
after age 45 years, but asymptomatic then
what investigation can be done age related macular degeneration if suspecting choroidal neovascularisation
fundus fluorescin angiogram. optical coherence tomography (OCT)
management age related macular degeneration
intravitreal VEGF inhibitors- bevacizumab and ranibizumab (wet); laser photocoagulation(wet); intravitrealsteroids; antioxidants and vitamins
pathogenesis open angle glaucoma
aqueous humour drains through trabecular meshwork in angle between cornea and iris. over time it undergoes morphological change. rise in IOP transmitted to optic disc where nerve fibre damage occurs
risk factors open angle glaucoma
genetic, increasing age, DM, myopia, black race, thin cornea
features open angle glaucoma
no symptoms until so advanced that central vision is threatened, no headache, eye pain, loss acuity
signs open angle glaucoma
increased IOP, optic disc cupping, peripheral visual field loss
optic disc exam open angle glaucoma
rim becomes pale and cup enlarges. cup:disc ratio
what cup:disc ratio suggests glaucoma
0.6. also asymmetry between the eyes of 0.2 is significant. (normal 0.4-0.7)
how to examine optic disc
stereoscopic viewing through a dilated pupil. OCT optical coherence tomography
visual field defect open angle glaucoma
central scotoma
treatment open angle glaucoma
prostaglandin analogues- latanoprost, travoprost- incr aqueous outflow through uveoscleral route rather than trabecular meshwork; B blockers to reduce production humour- timolol, betaxolol; alpha adrenergic agonists- brimonidine; carbonic anhydrase inhibitors; miotics- pilocarpine; sympathomimetics
surgery option in open angle glaucoma
trabeculectomy
which fields are lost first inopen angle glaucoma
nasal and superior fields, temporal are lost last
what is optic disc cupping
loss of disc substance. if >0.9 cup:disc ratio then severe cupping
what is a cataract
opacity in the lens
what happens to the red reflex in cataract
still present in an immature cataract, but absent in dense cataract
what morphological variants can occur with cataract
nuclear sclerosis- common in old age, subcapsular- shallow opacification can be from steroid use; cortical; dot opacities
pre senile cataract causes
diabetes, corticosteroid therapy, atopy, galactosaemia, hypocalcaemia, dystrophia myotonica
causes of congenital cataract
1/3- autosomal dominant. 1/3- birth trauma or maternal infection- rubella, toxoplasmosis.
presentation cataract
blurred vision, unilateral often unnoticed but loss of stereopsis affects distance judgment. bilat causes loss of vision, dazzle, monocular diplopia
how may cataract present in children
squint, loss of binocular function, white pupil, nystagmus
treatment of cataract
prior to surgery- ocular biometry. surgery- lens extracted and another lens inserted- Perspex, acrylic, silicon. antibiotic and anti-inflammatory drops post op
post op complications after cataract
posterior capsule thickening, astigmatism, eye irritation, rare- VH, retinal detachment, glaucoma
prevention cataract
photoprotection- sunglasses. UV-B. decrease oxidative stress
signs in optic atrophy
discs are pale. may be from incr IOP or retinal damage (choroiditis, retinitis pigmentosa); or ischaemia
causative toxins optic atrophy
tobacco, methanol, lead, arsenic, quinine, carbon bisulfide
causes optic atrophy
toxins, lebers optic atrophy, MS, syphilis, tumours
what is visual loss usually due to in diabetic retinopathy
vitreous haemorrhage, maculopathy
what happens in diabetic retinopathy
accelerates formation age related cataract, causes ocular ischaemia-new blood vessels to form on iris leads to glaucoma if prevents drainage of the aqueous fluid
classification diabetic retinopathy
background, pre proliferative and proliferative
what does vascular occlusion lead to diabetic retinopathy
ischaemia and new vessels forming in retina, otic disc, iris- proliferative retinopathy
features of background retinopathy
microaneurysms, dot and blot haemorrhages, exudates
features pre proliferative
cotton wool spots, venous beading, exudates
features proliferative
new vessels at the disc, and elsewhere. cotton wool spots, flame shaped haemorrhages- ruptured microaneurysms
what do cotton wool spots show
ischaemic nerve fibres
what is maculopathy
leakage from vessels close to the macule cause oedema and threaten vision
treatment diabetic retinopathy
good control diabetes, keep BP
what can you treat diabetic macular oedema with
intravitreal triamcinolone and anti VEGF drugs
what can be a complication in diabetic retinopathy
vitreous haemorrhage
what factors can accelerate retinopathy
pregnancy, dylipidaemia, icr bp, renal disease, smoking, anaemia
