Cataracts ✅ Flashcards
When can cataracts develop?
Can be present from birth, or develop and become visually significant with time
What happens to the lens throughout life?
It grows in size as layers of lens fibres are laid down
What do the layers of lens fibre encircle?
The fetal and embryonic nucleus
Which molecule does the lens have a high content of?
Protein (highest content of any tissue in the body)
What are the proteins in the lens called?
Crystallins
Why is the lens transparent?
Due to the accurate organisation of crystallins within it
What can cause opacification of the lens?
Disorganised protein fibre structure within the lens
Accumulation of abnormal metabolic products within the lens
How common are congenital cataracts? A
Occur in 2/10,000 live births
How are congenital cataracts usually identified?
Through screening
In what scenarios might congenital cataracts arise?
- Idiopathic (majority of cases)
- In children with family history or parental consanguinity
- As part of a syndrome
- As a complication of other ocular malformations
What % of children with isolated bilateral congenital cataracts will have a family history or parental consanguinity?
20%
What are cataracts in children with family history or parental consanguinity often secondary to?
Point mutations in genes such as MAF and CRYA1
What syndromes are cataracts often a feature of?
Many different syndromes, particularly Down’s
What is the prevalence of congenital cataracts in Down’s syndrome?
1.5%
Give an example of an ocular malformation that may be complicated by cataracts?
Aniridia
What investigations should babies born with sporadic bilateral congenital cataracts undergo?
- TORCH screen
- Galactosaemia screen
- Referral for genetic evaluation
What investigation should males born with sporadic bilateral congenital cataracts undergo?
Urinary amino acid assessment
Why should males with sporadic bilateral congenital cataracts have urinary amino acid assessment?
To exclude Lowe syndrome
What do unilateral congenital cataracts most commonly result from?
Abnormal regression of the embryological hyaloid vascular system
What does the embryological hyaloid vascular system do?
Supplies the posterior lens during development
What are unilateral cataracts usually associated with clinically?
Mild microphthalmia
What is microphthalmia?
A condition where one or both of the eyes is abnormally small
Are unilateral congenital cataracts investigated?
Not generally
Are cataracts developing after the critical period of neuroplasticity generally associated with a better or worse visual prognosis?
Better
What are the causes of cataracts developing after the critical period of neuroplasticity?
- Genetic
- Uveitis
- Steroid therapy
- Radiation
How are visually significant congenital cataracts managed?
Surgery within the first 2 months of life
Why is it important to operate on visually significant congenital cataracts within the first 2 months of life?
To achieve good visual function
How can less dense congenital cataracts be managed?
Close observation and refractive correction
How can unilateral or asymmetrical congenital cataracts be managed?
Occlusion therapy (patching) of the better-seeing eye
What is the problem with performing ocular procedures on infants and children?
They develop severe ocular inflammation and fibrotic changes following intra-ocular procedures
How is re-opacification of the visual axis with scar tissue after cataract surgery prevented?
The posterior capsule and anterior vitreous are removed during the lensectomy procedure, and an intensive topical steroid regimen is prescribed post-operatively
What are the options for lens replacement in paediatric cataract surgery?
- Implantation of the eye with an acrylic intra-ocular lens (IOL) at the time of lensectomy
- Leave the eye aphakic (without a lens)
What is required in order to be able to implant an IOL at the time of lensectomy?
The globe to be otherwise normal
What is done if the child is left aphakic following cataract surgery?
A contact lens is used to replace the refracting power of the lens until the child is older
If an IOL is inserted following cataract surgery, what refractive error will the eye be left with?
Hypermetropic
Why is the eye left hypermetropic following cataract surgery?
To allow for the physiological myopic shift which occurs during ocular growth
How is residual hypermetropia following IOL insertion corrected?
With extended wear contact lens for the first year, and glasses after
