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Terms in this set (66)
what is a retinal dystrophy
group of hereditary disorders affecting the retina.
What are the two types of retinal dystrophies?
those that affect retina in general and those that affect the macula
What is retinitis pigmentosa
progressive dystrophies of the photoreceptors of the retina and of the pigment epithelium (which lies just underneath the photoreceptors).
What do retinitis pigmentosa px present with?
night vision problems, which progress to a slow loss of all peripheral vision; central vision is spared the longest. It is the leading cause of inherited retinal degeneration-associated blindness.
autosomal dominant (30-40%)
autosomal recessive (50- 60%).
autosomal dominant form
tend to have a milder course with a late, slow progression and preserved vision until the fifth or sixth decade.
is the most severe; central vision is usually lost by the third decade.
Isolated cases, with no family history, also commonly occur
Features of RP
Bone spicule pigmentation
Cystoid macular oedema
Peripheral field loss
Posterior subcapsular cataract
have hearing loss, which may be profound or partial with a congenital or late onset. This accounts for about half of all cases of combined deaf-blindness.
RP and hearing loss are associated
What are the signs of Bardet-Biedl syndrome or Laurence-Moon syndrome when associated with RP
Short stature, renal dysfunction, and polydactyly
The mucopolysaccharidoses may be associated with RP (e.g. Hurler's syndrome, Scheie's syndrome, Sanfilippo's syndrome), as well as the mitochondrial disorder, Kearns-Sayre syndrome, which manifests as ptosis, external ophthalmoplegia, and heart block.
Management of RP
-Referral to a low vision specialist is very helpful.
-Patients should make regular visits to an eye care specialist to screen for and treat any ocular complications such as cataracts, glaucoma and cystoid macular oedema.
-The use of sunglasses to protect the retina from ultraviolet light may help preserve vision. Bright light can provoke the formation of free radicals which are damaging to the epithelium.
-Genetic counselling is important and family members (siblings and offspring) should be examined for evidence of RP.
-General counselling by experienced staff is vital. It is worth noting that most children will have enough sight to complete their education in normal schools.
-The DVLA will need to be informed (by the patient) and there will be a requirement to do a specialised (Estermann) visual field test which is carried out by DVLA approved optometrists; this is a legal requirement.
-Eventually, blind or partial sight registration.
What may be useful in treating patients with RP
Acetazolamide cystoid oedema may respond to oral carbonic anhydrase inhibitors, such as acetazolamide, with some subjective improvement in visual function.
congenital stationary night blindness
covers various problems which may or may not be associated with abnormalities in the fundus nyctalopia (night blindness) as a result in a delay or an inability to achieve normal darkadapted rod thresholds.
methods of inheritance of night blindness
AD, AR or XL
what might night blindness be associated with?
myopia, nystagmus and strabismus.
prognosis of night blindness
lebers congenital amaurosis
children are blind from birth or within the first few years of life. They exhibit the characteristic 'oculodigital syndrome': constant rubbing of the eyes results in orbital fat resorption and subsequent endophthalmos (eyes sunken into sockets).
prognosis of lebers congenital amaurosis
inheritance of lebers congenital amaurosis
How is lebers a multisystem disease
Eyes - blindness or hypermetropia, keratoconus (cone-shaped cornea), keratoglobus (large cornea), early cataracts, nystagmus
Nervous system - learning disabilities, deafness, epilepsy
Other systems - renal and musculoskeletal abnormalities, endocrine dysfunction
causes progressive loss of vision due to degeneration of the choroid and retina.
Who does choroideremia affect almost exclusively
what is the common first symptom of choroideremia in children?
night blindness is the most common first symptom.
what happens in choroideremia as it progresses
As the disease progresses, there is loss of vision, frequently starting as an irregular ring that gradually expands both in toward central vision and out toward the extreme periphery. Progression of the disease continues throughout the individual's life.
inheritance of choroideremia
what are macula dystrophies
Inherited disorders primarily affecting central retina
• In many cases present at a young age
• May have profound implications for family
• May give us information about AMD
age of onset of stargardts
Mean age of onset 15.2years
Age at visual loss onset 4 to 65 years
inheritance of stargardts
what does vision go down to in stargardts
Most patients experience decrease of vision to 6/120-6/60
What would you see on the fundus of a stargardts px?
Vermillion fundus (reddish)
Pisciform yellow flecks at level of RPE, extend to equator, extend to geographic atrophy of central RPE
What would be seen when doing a fluorescein angiography in a person with stargardts
Fluorescein angiography obstruction of normal choroidal fluorescence (dark silent choroid)
what levels are increased in stargardts and what is the result of this
Increased levels of lipofuscin in RPE ABSORBS BLUE LIGHT
electrodiagnostic tests in stargardts
Marked variation in results
• Multifocal and Pattern ERG abnormal in most patients with visual loss -useful as functional assessment
• ERG most usually cone pathway affected rather than rod pathway
• If normal photopic and scotopic ERG unlikely to develop abnormalities on follow up
More extensive retinal involvement of stargardts
onset of Fundus flavimaculatus
Encodes ABCR protein
ABCR acts as transmembrane transporter in rods of all-trans-retinal
Impairment of ABCR in STGD1 leads to build up of all-trans-retinal and build up of lipofuscin and RPE toxicity and photoreceptor degeneration
What advice should you give someone with stargardts
Avoid vitamin A and betacarotene supplements as they act as precursors to 11- cis -retinal
• Avoid over exposure to sunlight -it may increase photo-oxidative damage
is a Vitelliform macular dystrophy
inheritance of bests disease
What are the 5 stages of bests disease
Vitelliruptive phase - "scrambled"
may be multiple and eccentric
up to watch stage is vision normal
until stage 4 - scrambling
what can develop in atrophic stage
EOG and ERG in bests disease
EOG characteristically abnormal ,ERG is usually normal
what is besoprotein thought to be used for?
important in normal fluid transport across the RPE.
what is the yellow material
heterogeneous material which derives from degeneration of RPE cells
Adult onset (foveomacular) vitelliform macular dystrophy (AVMD)
• Characteristic onset in mild loss of vision in 40 years plus
• Bilateral symmetrical appearance of yellowish material
• Characteristic pigmentary change
• Normal EOG
• Usually no family history,
• AD inheritance reported
• May be asymptomatic
Most common macular dystrophy
What do they affect?
• Affect the RPE, bilateral and symmetrical
• Generally mild disturbance of vision
• Commonly AD
• Accumulated yellow material at level of RPE
Gass clasification of pattern dystrophies
1. Adult-onset vitelliform macular dystrophy
2.Butterfly-shaped macular dystrophy
4.Multifocal pattern dystrophy like Stargardt's
5. Fundus pulverulentus
pattern dystrophies associated with
pseudoxanthoma elasticum and myotoinic dystrophy
EOG and ERG in pattern dystrophies
Marked variation, and change in lesions. May have subnormal EOG but normal ERG
Retinal drusen related dystrophys
doyne honeycomb dystrophy
risk factor for
where is the drusen found
• AD inherited - are they all related?
• May be confused with AMD
• Malattia leventinese - radial drusen
• Doyne honeycomb dystrophy
• Usually show drusen deposits in early
• Risk factor for CNV
• Drusen at macula and around optic disc
sorsby's fundus dystrophy
• Early onset of reduced night vision in 20-30's
• Loss of central vision in later life due to cnv
• Drusen and yellow fundal deposits early finding
• Accumulation of lipid material in inner portion Bruchs membrane
• Vit A supplements may reduce night blindness
DDx of dystrophy and AMD
Drusen visible younger
Drusen around optic disc and macula
Very symmetrical appearance between eyes
Marked dominant family history
May have other features - night blindness in SFD, radial drusen
Drusen 60 yrs +
Drusen situated at macula
Not completely symmetrical
FH not so obvious
• X-linked inheritance - affects males only/ females carriers
• Early onset in childhood
• Classic appearance "wheel with spokes"
• Some peripheral schisis may be present
• Splitting of nerve fibre layer
• Characteristic reduced b-wave amplitude
• May be complicated by vitreous haemorrhage and retinal detachment
stationary cone dsytrophies
• May be stationary or progressive
• Progressive CD separate group
• Stationary cone dystrophies = cone dysfunction syndromes
Blue cone monochromatism
• Visual fields - central scotoma
progressive cone dystrophies
appearance in late cases
• Present in teens or early adulthood
• Progressive early loss of colour vision, day blindness/photophobia
• Nystagmus is common
• Colour vision abnormalities present early - usually all colour axes affected (tritan defect)
• Bull's eye appearance in late cases
• Pure PCD will have reduced cone responses but normal rod function
• Proportion of PCD will progress to cone-rod dystrophy with night blindness
• Inheritance variable - AD,AR X-linked
Bulls eye maculopathy is seen in which diseases
• Progressive cone dystrophy
• Rod-cone dystrophy
• Benign concentric macular dystrophy
• Stargardt's Disease
• Batten's disease
• Chloroquine maculopathy
• Geographic atrophy in dry AMD
AD cystoid macular oedema
changes in later life
• Photophobia key symptom
• Differential diagnosis X-Linked juvenile retinoschisis
• Atrophic changes in later life
central areolar choriodal dystrophy
how is it diagnosed
• Looks like dry AMD
• Usually AD inheritance
• Small areas of juxtafoveal atrophy in early phases
• Late phase localised GA in 60-70's
• Diagnosed by family history
North carolina macular dystrophy
• AD disorder but variable phenotype
• Usually non-progressive
• Early onset diagnosed in childhood
• Drusen like appearance early - atrophic coloboma in late phases
How to diagnose these unusual conditions
• Take a history
Age of onset?
Remember AMD is a disorder of elderly patients!
What is vision like at night?
What is it like in sunny conditions?
What about colour blindness?
Is the person easily dazzled or photophobic?
If a child what have the parents noticed?
Is there anyone else in the family affected?
Are the parents related?
• Visual acuity distance and near
• Colour vision - ishihara
• Look for nystagmus. Unusual refractive errors
• Fundus photography helpful
• Look for symmetry between eyes
• Remember full eye examination important
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