Visual Loss Flashcards
Describe the normal anatomy of the optic disc
- The areas of the optic disc and optic cup are correlated to each other (i.e. the larger the disc, the larger the cup)1
- The size of the optic cup may vary tremendously1
- In most normal eyes the rim tissue area is constant1
Patient history for glaucoma
- History of presenting complaint
- Including incidence, duration, severity and triggers of visual symptoms of glaucoma
- Ophthalmic history
- Trauma, previous eye surgery or laser, previous ophthalmic medications
- Medication history
- Social history
- Family history
- Risk factors in family
- Blindness or eye disease in the family
All patients with suspected glaucoma should undergo a physical eye examination that includes the following investigations:
- Slit-lamp examination
- Applanation tonometry
- Gonioscopy
- Optic nerve head and retinal nerve fibre layer evaluation
- Visual field examination (perimetry)
- Visual acuity
- Pachymetry
features of POAG normal pressure glaucoma
- > 35 years
- Normal IOP without treatment
- Asymptomatic until field loss advanced
- ONH: typical damage
- VF: typical, paracentral defects
- Gonio: open anterior chamber angle*
- No history or signs of other eye diseases or steroid use
OAG suspect
• VF, ONH and RNFL normal or suspicious
features of Ocular hypertension
- IOP > 21 mm Hg
- VF: normal
- ONH/RNFL: normal
- Gonio: open anterior angle*
- No other risk factors
Acute angle-closure signs
- IOP > 21 mm Hg, often to 50 to 80 mm Hg
- Decreased visual acuity
- Corneal oedema
- Shallow or flat peripheral anterior chamber
- Peripheral iris pushed forward
- Gonio:iridotrabecularcontact360degrees
- Pupil mid dilated and reduced with no reactivity
- Gonioscopycluesfromothereye
Signs of Intermittent angle- closure
- Features vary according to amount of iridotrabecular contact • Optic disc rim may show atrophy with an afferent pupil defect • Mild,intermittentsymptomsofacuteangle-closuretype
- Resolves spontaneously
signs of Chronic angle-closure
- Gonio: peripheral anterior synechiae of any degree
- IOP > 21 mm Hg
- Visual acuity may be normal
- ONH damage compatible with glaucoma
- Superimposed iridotrabecular contact possible
OVERVIEW OF PHARMACOLOGICAL treatment of glaucoma
• IOP reduction is the only treatment option we have
• Neuroprotection
Glaucoma & IOP reduction • 20% reduction in IOP reduces progression by 50%
- Beta blockers (1978)
- Timolol, betaxolol (betagan)
- Prostaglandin analogues (1996)
- Latanoprost (xalatan), bimatoprost (Lumigan), travoprost (Travatan) • Alpha agonists(1988)
- Brimonidine (alphagan), iopidine
- Carbonic anhydrase inhibitors (1995)
- Dorzolamide (Trusopt), brinzolamide (Azopt)
side effects of Beta blockers for glaucoma
- Beta blockers (1978)
- Timolol 0.25% & 0.5%, betaxolol (betagan)
- 20-27% reduction in IOP • Twice daily regime
- Bronchospasm
- Bradycardia
- Hypotension
- One drop of 0.5% may lead to 10mg oral dose equivalent
What drug os first line for glaucoma? list some side effects
Prostaglandin analogues • 20-35% reduction in IOP • Associated with decreased rate of glaucoma surgery in 1990s • First line • Once daily at night • Well tolerated • lash growth • Iris darkening • Dark circles under eyes
Cataracts Definition
- An opacity that forms within the lens of the eye which can reduce the transparency of the lens
- Most common cause of blindness in the world
Cataracts clarification
• Often classified according to part of lens primarily affected
• Nuclear – central part of lens, most common, change the refractive index
• Cortical – in the outer layer
• Sub-capsular – directly under lens capsule,
anterior or posterior
• Sub-classifications sometimes used by specialists, including severity, maturity and aetiology
Risk factors for acquired cataract
- Ageing (most occur in >60s)
- Trauma (blunt or penetrating injury, electric shock, radiation, surgery)
- Systemic disease (diabetes mellitus, myotonic dystrophy, NF type 2, severe atopic dermatitis)
- Drugs- corticosteroids
- Family history
- Social history- Smoking/ Cumulative exposure to UV light
Ocular conditions associated with cataract
- Trauma
- Uveitis
- High myopia
- Topical medication (particularly steroid drops) • Intraocular tumour
Clinical features cataract
- Unilateral cataracts may often be unnoticed but loss of stereopsis may affect distance judgement
- Gradual and painless reduction in V/A (difficulty in reading, recognising faces, watching TV)
- Difficulties due to glare (problems with bright sunshine, oncoming headlights when driving at night)
- Frequent changes of spectacle prescription
- Monocular diplopia
- Opacities and reduced red reflex on ophthalmoscopy
Differential diagnosis Other causes of painless gradual visual disturbance include
• Refractive error • Age-related macular degeneration • Primary open-angle glaucoma • Presbyopia • Some types of corneal disease • Chronic uveitis • Chemicals or drugs — eg methanol, chloroquine, hydroxychloroquine, isoniazid, thioridazine, isotretinoin, tetracycline, ethambutol • Pituitary tumour • Diabetic lens — undiagnosed or uncontrolled diabetes can cause vision changes • Diabetic retinopathy/maculopathy • Retinoblastoma — nearly always affects children <5 (pupil may look white (loss of red reflex),
Management cataract
- If not already seen optometrist, encourage patient to see one (to assess V/A and exclude other causes of visual impairment)
- Provide advice on fitness to drive
- Consider referral for surgery
- Visual impairment which is affecting lifestyle (eg driving, reading)
- Comorbidity that may benefit from surgery (eg risk of falls)
- Surgery would facilitate treatment/monitoring of other eye conditions eg retinal screening for diabetics
- If person has capacity to cooperate with exams, surgery and post-op drops
Post-op complications cataracts
- Intraoperative:
- Posterior capsule rupture and/or vitreous loss (communication between anterior and posterior chambers)
- Early complications:
- Bruising of eye or eyelids
- Infective endophthalmitis (very rare, may lead to loss of sight or eye)
- Refractive surprise (unexpectedly large need for glasses)
- Later complications
- Posterior capsule opacification (takes months to years) – treatable by laser, most common complication
- Detached retina (may occur weeks or months after surgery
- Dislocation of implant lens
Cataracts in children
- Much less common than in adults
- Babies screened for congenital cataracts at birth and at 6-8 weeks of age
- Present with poor vision, a white/grey pupil, nystagmus, strabismus, light sensitivity
- Unilateral cataracts usually idiopathic and non-hereditary
- Bilateral cataracts either idiopathic in 60% cases or
- Hereditary (most often autosomal dominant)
- Intrauterine infections (rubella, varicella, CMV, HSV, toxoplasmosis) • Genetic syndromes (Down syndrome, Edward’s syndrome)
Cataracts Prognosis
Adults
• Without treatment
Prognosis
• Steady decline in V/A without chance of recovery (rate of progression variable and unpredictable), leading to severe visual impairment
• With surgery
• Around 95% will have 6/12 best corrected vision on a Snellen chart
(meeting UK driving requirements)
• Generally very safe procedure but small minority develop complications which can be sight-threatening
• Children
• If congenital ones not removed within about 6 weeks of life, deprivation
amblyopia and lifelong visual impairment likely to occur
• Some visual improvement may be possible if treatment delayed or
lid lacerations management
if it closes lid margin medial canthus, lacrimal apparatus, or associated iwrh globe perforations must be referred to ophthalmologist. all others repaired with 6/0 mono filament
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