Gradual loss of vision 1 Flashcards
Why is gradual loss of vision impairment ?
Loss of vision is a very common problem
Patients are usually very anxious
Prompt appropriate action may be sight-saving
How do you classify loss of vision
Gradual and sudden
What is 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
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 some of the most common causes of gradual vision loss in elderly patients
Cataract
Chronic open angle glaucoma
Macular degeneration
Or any combination of all three
What is the name catarct derived from?
the intense white colour of a cataract of water.
How do cataracts progress?
They usually progress but the rate of progression is highly variable (usually years but occasionally weeks or months)
What are some of the features of catarcts
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
What are some more features of a catarct?
It continues to enlarge through life
Change in lens shape allows accommodation (focussing for reading) and Loss of ability to
change shape is called presbyopia (onset during 5th decade).
Intraocular lenses do not change shape hence, the loss of accommodation following cataract surgery.
Where does the cataract form?
The surface ectoderm
What is an age related cataract?
This type of catarct is associiated with advanced age and it is common
What are the common features of an age related cataract
Decreasing visual acuity
Increased difficulty reading/watching TV
Glare from bright lights
Decreased contrast sensitivity
Change in glasses prescription (more myopic)
Monocular double vision or ghosting
What are the types of cataract
Nuclear
Cortical
Posterior supcapsular
Can cataracts remain asymptomatic for years?
Yes, but eventually VA is reduced
What can nuclear catarcts lead to?
myopia
What can a cortical cataract cause?
glare, haloes and occasionally
double vision
What can posterior subcapsular catracts cause?
Poor vision in bright light
Is colour vision effected by catarcts ?
yes especially blue light
What is a nucelar sclerotic cataract?
It is the most common. It Affects the central (nuclear part of the lens). It causes a Myopic shift, Change in colours, Decline in VA and Glare
What is a posterior subcapsular cataract
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
What is a cortical cataract?
It develops in the outer layer (cortex) of the eye’s lens, appearing as white, wedge-shaped spots or streaks that can progress towards the center, causing blurry vision and glare
can cause double and even triple vision
pts can have good vusion as the central part of the lens is clear
What is a christmas tree cataract
A rare type of cataract characterized by multicolored, needle-like crystals within the lens, giving it a shimmering, “Christmas tree” appearance
Can catarcts be caused by blunt eye injury
Yes, a ‘sunflower’ cataract can be caused by a blow to the eye. The lens gets knocked out of place because of damage to the zonules (dislocation).
What is a congenital (zonular) cataract
In this child the central part of the lens is opaque.
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 is a secondary cataract associated with
Ocular diseases, medical treatments and systemic disorders
What eye diseases is a secondary catarct associated with
Fuch’s Heterochromic cyclitis
○ Iris colour, KP, vitreous abnormalities
● Iritis
● Aniridia
● Retinitis pigmentosa
● Iron intraocular foreign body
● High pressure
What treatments is a secondary cataract associated with
Steroids-topical and systemic
Glaucoma treatment
Radiation
Vitreous surgery
Antipsychotic drug
What systemic illness is a secondary cataract associated with?
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 is the criteria for catarct surgery?
Impact of lens opacity on daily life
Impact on VA
Catarct surgery
Day case surgery is appropriate for over 95% of patients. Visual rehabilitation is very rapid with modern techniques
Cataract surgery procedure
Most common elective surgical procedure in >65s
● Day Case
● Mostly LA
● Drops in eye for one month afterwards
● 1% Complication leading to worse vision
● 0.1% Serious complication which could lead to blindness
Phaco emulisification
Phaco= lens
Emulsification = fragmentation of lens fibres using ultrasound
What is phacoemulsification
● 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
Cataract surgery step 1
A sloping incision is made in the peripheral cornea
This incision is designed to be self-sealing
Cataract surgery step 2
A circular opening is made in the anterior capsule of this lens.
Cataract surgery step 3
The lens is removed using a probe which has three functions:
● Ultrasonic phacoemulsification
● Irrigation (saline)
● Aspiration (of lens material)
Cataract surgery step 4
Cortical lens remnants are removed by simple aspiration and irrigation until a clear ‘bag’ is
created to support the intraocular lens implant
● The IOL’s now come in a ready-made syringe
● Hydrate the wounds to avoid losing any bits of Iris
● Give antibiotic to anterior surface of eye to avoid infection
What are some examples of intraocular lenses
Optic
Haptic
1 piece
3 piece : used when lens is not going into the bag
Complications post cataract surgery
Most surgery is free of complications -95%
What are some possible intraoprative complications
1- Posterior Capsule rupture which can lead to Vitreous loss and retinal rupture, dropped nucleus or No support for the IOL so it drops to the back of the eye.
2- Iris trauma: which can leave a patient with two pupils or smaller one
3-Intraocular/suprachoroidal haemorrhagecanbe severe.Bleedingcanstartandthewholeeye
expels itself through the front of the eye especially in hypertension and high pressure.
In the event of a posterior capsule rupture, IOL can be placed in ciliary sulcus or anterior chamber.
IOL IN SULCUS
What are some further postoperative problems
- Intraocular lens dislocation
- Capsule opacification : It is a usual problem, regrowth of lens cells on posterior capsule within
months/years post-op. It brings back symptoms hence, can be removed with YAG laser. - MaculaOedema:becomessymptomaticwithreducedvisionbecausecystsdevelopatthe
macular about a month post-op, treated with anti-inflammatory drops and steroids. - Intraocular infection-endophthalmitis: very uncommon, upto 7 days post-op. Can present with
painful, red, reduced vision and hypopyon. It is urgent and serious. Will need intravitreal
antibiotics or even virectomy. - Uveitis, including rarely severe inflammation
Risks for cataract surgery
○ 1/20 will have a mild complication which may require additional treatment (e.g. CMO, PCO)
○ 1/100 intra-operative complication which might result in need for additional procedures and the vision may get worse instead of better (i.e. PCR)
○ 1/1000 risk of serious complication which could need significant further treatment/surgery and may lead to complete loss of vision and in worst cases loss of the eye (SCH, Endophthalmitis)
What is glaucoma
Glaucoma is an optic neuropathy characterised by cupping of the optic nerve with corresponding visual field defects due to loss of retinal nerve fibre layer with the main risk factor being raised intra- ocular pressure.
Is raised IOP always glaucoma
Raised IOP does not equal glaucoma. It only becomes glaucoma when there is damage to optic nerve.
How does high IOP cause ON damage
It is unknown.
● Raised IOP causing mechanical damage to axons?
● Raised IOP reducing blood flow at nerve head and then causing damage to axons?
What is the pathophysiology of a glaucoma
aqeous is produced by the ciliary body
actively secreted into posterior chamber – ultrafiltration and active transportation In front of the lens, through the pupil into AC
What are the two routes for the aqeous to leave the eye
Conventional: trabecular meshwork to schkemm canal to episcleral veins to blood stream
Unconventional: The uveoscleral roure (4%) : across the ciliary body into suprachoroidal space
What is teh order of structures in irido corneal damage
Iris
Ciliary body Scleralspur Trebecular meshwork Schwalbe’s line
Glaucoma classificication
0- closed angle
1- very narrow
2- narrow
3- open angle
4- wide open angle
What is primary open angle glaucoma
It is the most common type of glaucoma in UK. Prevalence of 1% over 40 years and increases to 80% over 80 years old. It is less common than cataract.
Equal prevalence between males and females. More common in black people than white. At risk of developing it if myopic or have diabetes.
It is often asymptomatic and usually found by opportunistic screening.
What are the features of POAG
● High IOP (typically 22-40mmHg)
● Open angle
● White eye, clear cornea
● No PXF, PDS
● Pathologically cupped optic disc
● Visual field defects
How is an OCT used in glaucoma
OCT used to monitor the thickness of optic nerve e.g retinal nerve fibre layer and progression of glaucoma.
Difference between neurological and glaucoma visual fields
Glaucoma fields often cross over unlike neurological which don’t.
What is the treatment for POAG
Medical
LASER
Surgery
Treatment aimed at lowering IOP to reduce risk of progression
Which drugs are commonly used in glaucoma treatment
- PROSTAGLANDINS – latanoprost – first line use, consider using in both eyes due to possible
symmetry cause my longer lashes. It Increase outflow via uveoscleral route (end in prost but
can be zalatan due to commercial name) - Betablockers – end in lol- decrease secretion of aqueos
- Pilocarpine-Miotic
- A-agonist – Brimonidine – Dual action – increase outflow and decrease secretion
- Carbonic anhydrase inhibitors (CAIs)
What is the benefit of laser for POAG
Evidence that Selective LASER trabeculoplasty (SLT) may be best for first line treatment and
reduce/negate need for drops.
● Trabulectomy- there will be a hole in the iris, under the lid called trabulectomy bleb. A
trabeculectomy bleb is a small cyst that forms in the conjunctiva, the thin, transparent layer that covers the white of the eye. It’s created when a surgeon makes a small hole in the eye to allow fluid to drain out, which helps lower eye pressure.
What are some complications of a trabeculectomy
- Hypotony – very soft eye leading to choroidal detachment
● Failure
● Scarring causing failure (MMC)
● Intraocular infection (blebitis)
What is Microinvasive Glaucoma Surgery (MIGS)
Not as good as trabulectomy as trabulectomy can bring pressure low quite quickly.
What is primary angle closure glaucoma
Less common. Prevalence of 0.1% over 40s. More common in Females than Males. More common in Hypermetropes and worse in people with progressing Cataract. Cant happen when cataract surgery done since large lens is changed.
Common in south east asians Asian due to narrow palpebral apertures?.
What are the symptoms of PACG
● Painful eye
● Photophobic
● Watering
● Loss of vision
● Nausea, abdominal pain, vomiting
PACG clinical findings
● Reduced VA
● Red eye
● Cloudy cornea
● IOP high (50-60mmHg)
● Fixed, mid-dilated oval pupil
● Shallow AC
● Closed angle (view may be difficult)
What is the treatment of angle closure glaucome
● Acetazolamide 500mg Intravenously (IVT) stat
● Acetazolamide 250mg po qds
● Pilocarpine 2% qds BOTH eyes ( constrict both pupils)
● Peripheral iridectomy BOTH eyes
● Consider phaco+IOL
What is secondary glaucoma- open angle
● Physical obstruction to aqueous outflow at the trabecular meshwork:
○ Blood in anterior chamber (hyphaema)
○ Inflammatory cells (uveitis)
○ Pigment (pigment dispersion syndrome)
○ Protein produced by lens/iris epithelium (pseudoexfoliation syndrome)
● Drugs increasing resistance to outflow (topical or systemic steroids, particularly topical)
● Structural damage to the drainage angle (blunt trauma)
What is secondary glaucoma- closed angle
● Neovascular glaucoma
● Choroidal or ciliary body tumours
● Uveitis
● Cataract (phacomorphic)
Summary of cataract
● Mostly ‘age related’ and incredibly common
● Treatment is surgery to remove lens and replace with IOL
● Rapid visual rehabilitation
