Lecture 21 - Diseases associated with LVL

Question 1

Albinisim: Describe and cause

Answer 1

Congenital condition characterised by lack of pigment
• Oculocutaneous albinisim
- Tyrosinase negative - reduced pigment (melanin) in the skin and eyes due to lack of enzyme tyrosinase
- Tyrosinase positive - reduced pigment (melanin) in skin and eyes, where the enzyme tyrosinase is present, but other factors reduce the production of melanin.
• Ocular albinisim (reduced pigment in eyes only)

Inheritance of oculocutaneous albinism
• autosomal recessive /autosomal dominant
• Patients with recessive form can be tyrosinase positive or tyrosinase negative
• Reduction in the amount of pigment (melanin) in each of the pigment organelles (melanosomes)
• Incidence = 1 in 20,000 general population

Question 2

Albinisim: Visual acuity, visual field and ocular signs + symptoms

Answer 2

Visual Acuity
• Tyrosinase negative:
- Most severe effect on VA
- 6/60 - 6/120
• Tyrosinase positive: Better acuity - improve over time (=6/24)
• Ocular: 6/7.5-6/30

Visual field
• Appears full

Ocular signs & symptoms
• Blue irises - transillumination
• photophobia
• nystagmus
• hypoplasia of the macula
• high incidence of strabismus
• poor stereopsis
• high refractive error (with the rule Ast)

Question 3

Albinisim: Systemic signs/symptoms and associated syndromes

Answer 3

Systemic signs & symptoms
• White or yellowish hair, eyebrows, eyelashes
• Pink skin, sensitive to sun damage
• Albinoidism

Associated syndromes
• Hermansky-pudlak: ( genetic metabolic disorder which causes albinism, visual impairment, a platelet dysfunction with prolonged bleeding, and - progressive symptoms including pulmonary fibrosis, inflammatory bowel disease and kidney disease)
• Chediak - Higashi: generalized cellular disorder which affects all granule-containing cells resulting in recurrent infections and ocular, neurological, and skin manifestations

Question 4

Albinisim: Low vision management

Answer 4

• Correct Refractive error
• Aperture control contact lenses
• Tints, UV protection (skin protection)
• Magnification for distance & near

Question 5

Cataract: Describe and Cause

Answer 5

• Opacification of crystalline lens
• Classification according to area affected
- Ant & post subcapsular
- Ant & post cortical
- Equatorial
- Nuclear

Inheritance/Etiology
• Trauma, metabolic, toxic, secondary to inflammation, pharmacologic, hereditary, age-related
• Approximately 95% over the age of 65 have some form of lens opacification

Question 6

Cataract: Visual acuity and visual field

Answer 6

Visual acuity
• will vary with the degree and location of the opacity most often bilateral but asymmetric
• nuclear sclerotic generally not associated with acuity loss - more myopic
• posterior subcapsular tends to have profound effect on VA -location - especially with papillary constriction

Visual field
• Generally not affected

Question 7

Cataract: Ocular signs and symptoms

Answer 7

Ocular signs & Symptoms
• Dull or abnormal Ret reflex
• Refraction more myopic
• Reduced acuity
• Increased glare
• Distortion, monocular diplopia
• Altered colour perception

Question 8

Cataract: Diagnostic testing, Medical treatment and low vision management

Answer 8

Diagnostic testing
• Interferometry
• Potential acuity meter (vernier acuity)
• Ultrasonography

Medical treatment
• Surgical removal
• Mydriatics

Low vision management
• Lighting critical
• Filters & antireflective coating for glare
• Magnification

Question 9

Diabetic retinopathy: Describe

Answer 9

• Around 2% of the UK population have diabetes, 200,000 - Type 1 and > 1 million
- type 2
• biggest single cause of registered blindness in the UK amongst working age people
• smoking & obesity increase risk type I will tend to show retinopathy within 10 to 12 years
• type I (after 20 years) - 60% will show some degree of retinopathy

Question 10

Diabetic retinopathy: Types and Signs & Symptoms

Answer 10

2 Types
• type l- juvenile onset: insulin dependent
• type lI - adult onset: non-insulin dependent

Signs & Symptoms
• Excessive thirst
• Excessive urination
• Excessive hunger
• Excessive fatigue
• Weight loss
• Recurrent infections

Question 11

Diabetic retinopathy: Visual acuity + Visual field

Answer 11

Visual acuity
• From 6/6 to total blindness
- Fluctuations due to blood sugar level if poorly controlled
- Lens changes (myopic)
- CMO (hyperopic)

Visual field
• Secondary complications can cause field loss
- laser burns
- retinal detachment
- glaucoma
- CMO - macular degeneration (MD)

Question 12

Diabetic retinopathy: Other ocular visual complications

Answer 12

** Other ocular/visual complications**
• Accommodative insufficiency
• Diplopia
• Cataracts
• Glaucoma (rubeosis irides)
• RD
• MD/CMO
• Decreased corneal sensitivity (CL wear)
• Neovascularization
• Hemorrhages

Question 13

Diabetic retinopathy: Low vision management

Answer 13

Low Vision Management
• Refraction
• Sunlenses & filters
• Increased illumination
• Magnification/minification
• Flashlight/torch
• Non-optical
• Mobility services support groups

Question 14

Glaucoma: Describe

Answer 14

Group of diseases in which damage to the optic nerve head (ONHoccurs due to increased intracular pressure, poor blood supply of the ONH, a weakness in the optic nerve structure or a combination of the three
• open angle
• angle closure
• developmental

Question 15

Glaucoma: Ocular symptoms

Answer 15

• open angle - asymptomatic
• angle closure
- pain
- blurred vision
- photophobia
- halos
- nausea & vomiting

Question 16

Glaucoma: Visual acuity + Visual field and diagnostic testing

Answer 16

Visual acuity
• Generally unaffected until end stage

Visual field
• Typically respects the horizontal midline
- Arcuate defects
- Nasal steps
• Gradually spreads to periphery and centrally

Diagnostic testing
• Optic nerve appearance
• Visual field
• IOP
• Anterior chamber angle

Question 17

Glaucoma: Low vision management

Answer 17

Low Vision Management
• Magnification
• Lighting (indoors & outdoors) e.g torch @ night
• Glare control, contrast enhancement
• minification
• peripheral awareness systems (prisms, mirrors)
• other professional services

Question 18

Macular holes: Describe, Visual acuity + field

Answer 18

• appearance: round, red spots in centre of macula
• 1/3 to 2/3 DD in size, may have grey halo around it (RD)
• may be caused by trauma, myopia, CMO, inflammation but most are idiopathic

• Visual acuity: depending on size and location generally 6/9 to 6/120
• Visual field: Full thickness holes generally result in dense central scotomas

Question 19

Macular holes: Signs+symptoms and low vision management

Answer 19

Ocular signs and symptoms
• Metamorphopsia
• Redudced acuity

Low Vision Management
• Magnification
• Eccentric viewing
• Lighting
• Filters to increase contrast

Question 20

Macular disease: Describe

Answer 20

• Any degenerative, inflammatory, toxic, vascular or dystrophic condition that affects foveomacular area
• Great variation in form, appearance, onset and involvement
• Majority of low vision patients suffer from some form of macular disease
• Some common macular diseases:
- ARMD (dry [atrophic [& wet[hemorrhaguc] type)
- Stargart’s disease (fundus flavimaculatus)
- Central aerolar choroidal dystrophy (CACD) (circumscribed area of RPE and choriocapillary atrophy in macula - hearing loss)
- Best’s disease

Question 21

Macular disease: Signs and symptoms

Answer 21

Signs & Symptoms
• Reduced acuity (distance and near)
• Metamorphopsia
• Central field loss
• Reduced colour vision
• Increased glare and photophobia

Question 22

Macular disease: Diagnostic tests and Low vision management

Answer 22

Diagnostic tests
• Field testing (Amsler grid)
• Colour testing (D 15 - usually red/green loss)
• Fluorescein angiography & electrodiagnostic testing

Low Vision Management
• Refraction
• Magnification (some do not respond favourably e.g CACD)
• Lighting
• Glare control, contrast enhancement, sunlenses & filters
• Non optical, support groups, auditometry etc.

Question 23

Myopic degeneration: describe

Answer 23

• Excessive stretching and expansion of the posterior segment
• Scleral & choroidal thinning
• Genetic but mechanism of transmission poorly understood
- Rapid increase in incidence and severity in some parts of the world (myopic degeneration is 2d highest cause of low vision in Hong Kong)

Question 24

Myopic degeneration: Visual acuity+ fields
and ocular signs/symptoms

Answer 24

Visual acuity
• Decreases as condition progresses
• May lead to “no light perception” (NLP) from secondary complications

Visual field
• Degree of field loss will vary with structures involved

Ocular signs and symptoms
• Blurred distance vision
• Flashes & floaters
• Thinning of RPE
• Posterior staphyloma
• Fuch’s spot
• Retinal detachment

Question 25

Myopic degeneration: Associated syndromes and los vision management

Answer 25

Associated syndromes
• Down’s syndrome
• Marfan’s syndrome
• Stickler’s syndrome (connective tissue disorder, also affecting joints, palate, heart and hearing)

Low vision management
• Refraction (contact lenses)
• Magnification (more so at distance)
• Lighting & contrast enhancement
• Glare control & photophobia protection
• Torch @ night
• Other professional services

Question 26

Retinitis pigmentosa: describe

Answer 26

• Family of hereditary, progressive retinal pigmentary degenerations
• affects about 1 in 3000-4000 of the population
• most common in males
- autosomal recessive
- autosomal dominant
- X-linked

Question 27

Retinitis pigmentosa: Visual acuity + field and ocular signs/symptoms

Answer 27

Visual acuity
• From 6/6 to NLP

Visual field
• Field loss begins in mid periphery extending inward and outward

Ocular signs+symptoms
• Nyctalopia
• Light/ dark adaptation affected
• Attenuated blood vessels
• Bone spicule pigmentation
• Waxy disc
• Posterior subcapsular cataracts (quite common)
• СМО

Question 28

Retinitis pigmentosa: Associated syndromes

Answer 28

• Usher’s syndrome (RP & deafness)
• Laurence - Moon Biedi syndrome (mental retardation, hypogonadism, pigmented retinopathy and renal tract abnormalities)
• Refsum’s disease (RP, peripheral polyneuropathy, and cerebellar ataxia)
• Alstrom’s syndrome (Retinal degeneration, nystagmus, obesity in childhood;
sensorineural hearing loss and diabetes mellitus)
• Leber’s congenital Amaurosis (strabismus, nystagmus, photophobia, cataracts; ceratoconus; hearing loss, mental retardation, and/or psychomotor retardation).

Question 29

Retinitis pigmentosa: Low vision management

Answer 29

• minification
• peripheral field awareness
• magnification
• sunlenses, CPF and tints
• lighting control, torch @ night
• genetic counselling

Question 30

Retinopathy of prematurity: Describe

Answer 30

• abnormal proliferation of retinal blood vessels in premature infants receiving oxyger therapy
• about 7% of babies in the UK are born prematurely
• vitamin E prophylaxis has been proposed to reduce severity of ROP

Question 31

Retinopathy of prematurity: visual acuity+field and Low vision management

Answer 31

Visual acuity
• From 6/6 to NLP

Visual field
• Variable depending upon which part of the retina is involved

Low vision management
• Refraction (contact lenses)
• Magnification (distance)
• sunlenses, filters to enhance contrast and reduce glare & photophobia)
• lighting control, torch @ night

Question 32

Retinopathy of prematurity: Ocular signs and symptoms

Answer 32

• High Myopia
• Strabismus
• Retinal Detachment
• Glaucoma
• Cataract
• Corneal Scarring
• Glare and photophobia
• Cerebral Visual Impairment