Gradual Loss of Vision Flashcards
Causes of gradual loss of vision
- cataract
- refractive error
- corneal blindness
- optic atrophy
- ARMD
- diabetic macular oedema
- chronic ocular inflammation/infection
Definition of blindness
VA <3/60 in the better eye
Who gets loss of central vision?
- ARMD
- Toxic optic neuropathy
Who gets loss of peripheral vision?
- retinitis pigmentosa
- glaucoma
2 types of cataract extraction
- ICCE (intracapsular)
- ECCE (extracapsular)
How is traditional ECCE done?
- needle used to make a hole in the lens capsule
- cataract is expressed by putting pressure on the base of the cornea
What is phacoemulsification?
- ultrasound probe is used to emulsify the cataract before sucking it out through a small wound
Causes of leukocoria
- cataract
- toxoplasmosis
- toxocariasis
- retinoblastoma
- longstanding retinal detachment
- persistent posterior hyperplastic primary vitreous
How does a pinhole work?
- only parallel rays of light pass through the hole so that the eye does not have to refract them to get a clear retinal image
Hyperopia
Long sightedness
Myopia
Short sightedness
Characteristics of degenerative myopia
- develop laquer cracks in Bruch’s membrane and may lose vision through haemorrhage from neovasculatisation round the cracks and retinal degeneration
What is keratoconus
Progressive myopic astigmatism
Characteristics of trachoma
- entropion (lower eyelid folds in)
- trichiasis (ingrown eyelashes)
- scarring of conjunctiva and cornea
Causes of interstitial keratitis
- congenital syphilis
- TB
- measles
Cause of climatic droplet keratopathy
Prolonged exposure to the elements
Causes of optic atrophy
- compression of optic nerve (tumour)
- damage to optic nerve head in glaucoma
- metabolic, infective and genetic diseases of the retina
- chronic papilloedema
Features of retinitis pigmentosa
- waxy pallor of the disc
- bone spicule pigmentary retinopathy
- attenuated blood vessels
- night blindness
- tunnel vision
Why do patients with ARMD develop loss of central vision?
- scarring
- leakage from subretinal neovascular membranes
- bleeding from SRNVM
How do you prevent LOV in ARMD
With early laser
What is band keratopathy?
Calcification of the cornea
caused by intraocular inflammation
Definition of glaucoma
An optic neuropathy characterised by:
- cupping of the optic disc
- characteristic pattern of visual field loss
- raised IOP
Ocular hypertension
Raised IOP, but no optic neuropathy or visual field loss
Risk factors for primary open angle glaucoma
- genetic (TIGR myocillin gene)
- Black African ancestry
- myopia
- age >45
- DM and HPT uncontrolled
Best way to test visual fields in glaucoma
Automated perimetry
Typical field defects in glaucoma
- arcuate defects
- nasal step
- ring scotoma
- tunnel vision
Management of glaucoma
- refer
- medical
- surgical (trabeculectomy)
Management of ARMD
- Laser/ anti-growth factor
Ocular features of JIA
Chronic uveitis with painless, insidious LOV due to:
- calcific band keratopathy
- cataract
- glaucoma
