gradual loss of vision (cataract) Flashcards
conditions that cause loss of vision gradually
usually chronic degenerattive , chronic disorders in the elderley
less common disorders include inhertied disorders of the retina or optic nerve such as retintis pigmentosa
types of conditions that cause sudden loss of vision
vascular and inflammatory dirosders
sometimes patients suddenly nptice a profound loss of vision that has actually been developing gradually
common causes of grdual loss of vision in the elderley
cataract
chronic open angle glaucoma
macular degeneration
or any combination of all three
gradual loss of vision in the eldelry patient common causes
catarct
chronic open angle glaucoma
macular degeneration
define catatract and presybyopia
Cataract is the name applied to any opacity or clouding in the lens
The lens formed from surface ectoderm
It continues to enlarge through life
Change in lens shape allows accommodation (focussing for reading)
Loss of ability to change shape is called presbyopia (onset during 5th decade)
describe the structure of the lens
The lens is avascular
It lies behind the iris
It is attached to the ciliary muscle by the zonules
It is made up of fibres derived from the anterior lens capsule
The nucleus is the oldest part of the lens
Fibres are continuously added around the nucleus throughout life, forming the cortex
charcateristics of cataract
They are often bilateral
All ages (even congenital) can be affected but they are usually age related
They can be associated with many syndromes (e.g. Down’s syndrome) but the majority are an ageing phenomenon
The prevalence of cataract is 90% over 80 years
white colour of the pupilin adavnaced stage of cataract
leucocoria
three types of cataract
cortical
nuclear
subcapsular
what is the progression of nucelar cataract with age asscoated with
associated with increased pigment discolouration
christimas tree cataract are called
polychromatic opacities in the lens
posterior subcapsular catract charcaterisitcs
Patients with this type of central cataract have good vision when the pupil is dilated e.g. in dim illumination
In bright light the pupil constricts and vision is profoundly reduced
reduced cv - especially blue
cortical cataract charcaterstics
Patients have good vision , may report glare , lights , halo can cause diplopia
cataract caused by a blunt injury to the eye looks like
This ‘sunflower’ cataract has been caused by a blow to the eye
The lens has also been knocked out of place because of damage to the zonules
congenital (zonular catarcat is caused by)
In this child the central part of the lens is opaque
Visual acuity can often be good so that surgery can be delayed until the child is visually mature (age 8-9 yrs)
Dense congenital cataracts in neonates require urgent attention to avoid amblyopia
what are some of the causes of secondary catract
Associated with other ocular disease
Associated with medical treatments
Associated with systemic conditions
catarcat is also associated with what other eye diseases
Heterochromic cyclitis
Iris colour, KP, vitreous abnormalities
Iritis
Aniridia
Retinitis pigmentosa
Iron intraocular foreign body
what other treatment are associted with catarcat
Steroids-topical and systemic
Glaucoma treatment
Radiation
Vitreous surgery
Antipsychotic drugs
what systemic ilness is associated with cataracts
Metabolic
Diabetes, galactosaemia, hypocalcaemia, Wilson’s disease, myotonic dystrophy
Skin disease-atopy
Genetic
Down’s, Alport’s, Lowe’s syndromes etc
Infection (maternal)
Rubella, CMV, syphilis
what symptoms are associated with cataracts
Cataracts can remain asymptomatic for years
Nuclear cataracts lead to myopia (short-sightedness) which can improve reading vision
Eventually visual acuity is reduced
Cortical cataracts cause glare, haloes and occasionally double vision
Posterior subcapsular cataracts cause poor vision in bright light
Loss of colour vision (especially to blue light) can cause problems e.g. artists
cataract surgery indications
The decision to operate is based upon an assessment of the impact of the lens opacity on daily life for each patient
Most surgery is performed under local anaesthesia
Day case surgery is appropriate for over 95% of patients
phacomeulsification process
Phacos = lens
Emulsification = fragmentation of lens fibres using ultrasound
The technique allows a small, self-sealing incision that does not require sutures
As the natural lens is removed the patient would be left with a high refractive error (usually needing a +12 dioptre lens)
This is avoided by the insertion of intraocular lens (implant)
Rapid visual rehabilitation (within 24 hours) is normal
cataract sx steps
sloping incision made peripheral conrea
incision = self sealing
circular opening made in anterior capsule of lens
lens removed using a probe - probe has 3 functions
ultrasonic pharmacemulsification
irrigation (saline)
aspiration of the lens material)
cortical lens remennts are removed by aspiration and irrigation until a clear bag is created to support the IOL implant
catarct sx problems
Most surgery is free of complications -95%
Intraoperative problems
The lens capsule may rupture which leads to vitreous prolapse and a ‘dropped’ nucleus,
Intraocular haemorrhage can be severe
Postoperative problems
Intraocular lens dislocation
Capsule opacification
Intraocular infection-endophthalmitis
Severe inflammation
