How is loss of vision classified?
- Gradual
- Sudden
What is Gradual Visual loss?
Gradual loss of vision
- Usually over weeks, months or years
- The sorts of conditions that lead to gradual loss of vision are chronic, degenerative disorders in the elderly
- Less common causes include inherited disorders of the retina or optic nerve such as retinitis pigmentosa
What is sudden loss of vision?
Sudden loss of vision
- Usually over minutes, hours, or a few days
- The sorts of conditions that lead to sudden loss of vision are vascular and inflammatory disorders
- Sometimes patients suddenly notice a profound loss of vision that has actually been developing gradually
What are common causes of gradual loss of vision in the elderly population?
Although not an exclusive list of causes, most patients who notice a gradual loss of vision have either:
- Cataract
- Chronic open angle glaucoma
- Macular degeneration
- Or any combination of all three
Where does the name cataract come from?
The name is derived from the intense white colour of a cataract of water
What is the rate of progression in cataracts?
Cataracts usually progress but the rate of progression is highly variable (usually years but occasionally weeks or months)
What are some features of cataracts?
- 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
- Cataract is the name applied to any opacity or clouding in the lens
- The lens formed from surface ectoderm and continues to enlarge through life
- Loss of ability to change shape is called presbyopia (onset during 5th decade)
What is a common cause of visual impairment and blindness in elderly, institutionalised patients?
Age-related cataract
What are some common presenting features of cataracts?
Common Presenting Features
- Decreasing visual acuity
- Increased difficulty reading/watching TV
- Glare from bright lights
- Decreased contrast sensitivity
- Change in glasses prescription (more myopic; lens becomes thicker and less flexible)
- Monocular double vision or ghosting
What are some symptoms of cataracts? Think nuclear, cortical and posterior subcapsular cataracts
- Cataracts can remain asymptomatic for years
- Nuclear cataracts lead to myopia (short-sightedness) which can improve reading vision (they might not want cataract surgery for this reason so it needs to be discussed with them)
- 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
What are some symptoms of Nuclear Sclerotic Cataract?
The most common
Affects the central (nuclear part of the lens)
- Myopic shift
- Change in colours
- Decline in VA
- Glare
What are the symptoms of Posterior Subcapsular Cataract?
Best shown against the red reflex - web-like opacity.
- 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 as right in the visual axis (as cataract sites right in the area where the pupil has constricted)
What are some features of cortical cataract?
In cortical cataract the central part of the lens may be clear
- Patients have good vision
- They may complain of haloes around lights, and glare
- They can cause double (or even triple vision)
What are ‘sunflower’ cataracts?
- Caused by blunt trauma to the eye
- 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 (dislocation)
What are the features of a congenital (zonular) cataract?
- 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 secondary cataracts associated with?
Other ocular disease
- Fuch’s Heterochromic cyclitis (iris colour changes, KP, vitreous abnormalities, anterior chamber inflammation)
- Iritis (anterior uveitis)
- Aniridia
- Retinitis Pigmentosa
- Iron Intraocular foreign body
Medical treatments
- Steroids-topical and systemic
- Glaucoma treatment
- Radiation
- Vitreous Surgery
- Antipsychotics
Systemic conditions
- Metabolic (diabetes, galactosaemia, hypocalcaemia, Wilson’s disease, myotonic dystrophy)
- Skin disease-atopy
- Genetic (Down’s, Alport’s, Lowe’s syndromes etc)
- Maternal Infection (rubella, CMV, syphilis)
What anesthesia is cataract surgery performed under?
Most surgery is performed under local anaesthesia
How many patients are day cases for cataract surgery?
95%
How often do you use drops for after cataract surgery?
Drops in eye for one month afterwards
What is left in place during cataract surgery?
Lens capsule
How common are visual difficulties after cataract surgery?
- 1% Complication leading to worse vision
- 0.1% Serious complication which could lead to blindness
Why do we want a small surgical incision in cataract surgery?
The larger the incision the higher the induced astigmatism we can cause
What is Phacoemulsification?
Cataract surgery
- Phacos = lens
- Emulsification = fragmentation of lens fibres using ultrasound
Phacoemulsification and vision
- 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
