Gradual Visual Loss Flashcards
What are cataracts
opacification of the lens causing decreased visual acuity
what is the leading cause of blindness in the UK
cataracts
by 100 years old, how many people get cataracts
basically 100%
How are cataracts characterised
by the anatomical location
what are the anatomical classifications of cataracts
posterior subcapsular cataracts
cortical cataracts
nuclear
what are some risk factors of posterior subcapsular cataracts
Diabetes
Steroids
What do posterior subcapsular cataracts do to vision
reduce acuity
reading distance affected the most
cause issues with direct bright light (as it gets refracted in the cloudy lens)
what are some risk factors of cortical cataracts
UV exposure
Diabetes
Drugs - corticosteroids, aspirin, K+ sparing diuretics
what do nuclear cataracts look like
yellowing nuclear sclerosis in the center of the lens
what are some risk factors for nuclear catarcts
milk intake
calcitonin
smoking
What is the aetiology of cataracts
Age-related Congenital Traumatic Metabolic Toxic (drugs) primary eye conditions systemic disease connective tissue disease CNS issues (sjorens, neurofibromatosis) Trisomy 21
what are risk factors for age related cataracts (apart from age)
allergy hyper/hypoension low IQ UV light infrared radiation Diabetes
how much of a genetic component do congenital cataracts have
about 1/3 are inherited
what are the types+ subtypes of congenital cataracts
total
partial - partial may be polar (ant or post), zonular (lamellar, stellate ,sutural, nuclear) or membranous
what causes traumatic cataracts
iris gets torn away from normal insertion causing damage
how do different types of trauma cause different types of traumatic cataracts
blunt trauma - rosette shape/posterior subcapsular
penetrating trauma whole lens opaque is large, is small usually a small area as it is self-sealing
What metabolic derangements cause cataracts
Diabetes Galactosaemia (GUPT deficiency) Galactokinase deficiency Wilsons Fabry's Lowes Decreased calcium menosidosis (genetic lysosomal disorder)
what kinds of cataracts do diabetes cause
snowflake opacities (only if true diabetic cataracts - otherwise may be age related)
what kind of cataracts are caused by galactokinase deficiency
lamellar opacity (wheel spoke)
what are causes of toxic cataracts
corticosteroids
chlorpromazine (anterior capsule)
chemo (buslphan)
what primary eye conditions cause cataracts
Uveitis
Hereditary retinal degenerations
High Myopia
Post Surgical
what systemic disease causes cataracts
cutaneous disease (atopic dermatitis)
congenital ectodermal dysplasia
werners/rothmond/thomson syndrome
what are immature, mature and hyper-mature cataracts
immature = not opaque fully yet mature = opaque hyper-mature = small wrinkled lens leading to fluid leakage
what are clinical features of cataracts
Decreased visual acuity
Glare (difficulty focusing in light)
Myopic shift (increase in refractive power causing slight-moderate myopia)
Mono-ocular Diplopia - double vision in one eye due to nuclear changes concentrating in inner refractive area in center of lens
What is ‘second sight’ in cataracts
myopic shift in cataracts in long sighted people causing restoration of normal sight
What investigations should be done for suspected cataracts
Diagnosis = history + slit lamp examination
If posterior-subcapsular pathology detected - ocular-B scan (ultrasonography)
refraction must be done
Accurate biometry also essential (axial length/keratometry) for lens replacement power calculation - must be equal to normal eye (if unilateral)
what are post-surgical complications of cataract surgery
corneal odema
corneal decompensation
What is the definitive treatment for cataract surgery
surgical lens extraction and replacement
What are the types of surgery for cataracts
intracapsular cataract extraction (ICCE)
extracapsular cataract extraction
Phacoemulsification
what are complications of intracapsular cataract extraction
severe astigmatism increased recovery visual rehab required leaks macular odema
when is intracapsular cataract extraction used
cases where zonular integrity is impaired severely, not allowing for ECCE
what is extracapsular cataract extraction
Removal of the lens nucleus through opening in anterior capsule retaining the integrity of posterior capsules cuaaing decreased trauma of endothelium
What is the most common catarct surgery
basically all of them are phacoemulsification
What is phacoemulsification
small incision in anterior capsule, ultrasound destruction of the lens whilst fluid is pumped in to maintain the pressure, hoovering up the lens + injection of new lens
How are patients acuity adjusted in cataract surgery
they’re made slightly myopic to enable some reading vision
what are complications of phacoemulsification
posterior capsule opacification (20%) vitreous loss (4%) retinal detachment (1%) endopthalmitis (0.1%)
What is endopthalmitis
acute bacterial infection causing absent red reflex, marked visual loss, pain, exudates and corneal haze
what bacteria cause endophthalmitis
pseudomonas
staph aureus
s.epidermidis
how do you treat endophthalmitis
eye drop antibiotics
what are the different types of macular degeneration
wet (10%)
dry (90%)
what is dry macular degeneration
gradual central vision loss, causing issues with recognising faces/reading
what fundoscopic feature is common with macular degeneration
drusen
what is the treatment for dry macular degeneration
there is none
what is wet macular degeneration
sudden onset of rapid visual loss and distortion due to choroidal vessel growth into the subretinal space, causing leakage and bleeding leading to retinal interference and atrophy
What are the fundoscopic features of wet macular degeneration
significant subretinal hemorrhage (early) +/- exudates and fibrosis (late)
what are the common features of wet and dry macular degeneration
loss of CENTRAL vision
distorted vision
what is the timeline of visual defects seen in macular degeneration
Drusen (on fundoscopy) ➜ many drusen ➜ paracentral scotoma (in vision) ➜ atrophic central vison (blind spot centrally)
what have protective effects (not curative) for macular degeneration
Vitamine A,C,E and Zinc
what is the pathological mechanism for dry macular degeneration
incomplete recycling of photoreceptors in the RPE leading to lysosomal accumulation, causing decreased nourishment of the photoreceptors from the RPE due to decreased diffusion gradient - leading to drusen
What are Drusen
Small deposits of lipid under the retina caused by the lysosomal accumulation
how do you treat wet macular degeneration
Laser photocoagulopathy - attempt to stop bleeding under the retina
Retinal Photodynamic Therapy
Anti-VegF (take monthly for years)
what is the treatment window for wet macular degeneration
1-2 week window from presentation to point where treatment is unavailable/unusable
If neovascularised macular degeneration is diagnosed what is important to do next + why
fluorescein angiography as it guides anti-VEGF therapy
