Cataracts

Question 1

What are cataracts?

Answer 1

• cataracts occur due to opacification of the lens.
• They are a major cause of blindness worldwide

Question 2

What is the pathophysiology of cataracts?

Answer 2

• The lens is a clear, biconcave structure at the anterior part of the eye
• It is composed of the capsule, epithelium, cortex and nucleus
• It is held together suspensory ligaments attached to the ciliary bodies

Question 3

What is the lens’s role in refraction?

Answer 3

• Refers to the change in direction of light when it passes from one medium to another
• Helps to converge light onto the retina

Question 4

What is the len’s role in accommodation ?

Answer 4

• Refers to the ability to maintain focus on an image as distance varies
• The lens achieves this by altering its shape through contraction or relaxation of the ciliary bodies

Question 5

How common is Cataracts?

Answer 5

• A very treatable cause of blindness
• More common as we age
• > 70% of patients over 85 years old had visually-impairing cataracts
• Global prevalence in patients >60 years old worldwide

Question 6

What are some of the causes of Cataracts in Adults?

Answer 6

• Age-related cataracts
• Trauma
• Uveitis ( inflammation of the pigmented layers: ciliary bodies, choroid and iris)
• Scleritis (inflammation of the sclera)
• Intra-ocular tumours
• Radiation
• Medications (corticosteroids)
• Systemic Disease (Diabetes Mellitus, Myotonic dystrophy, severe atopic dermatitis)

Question 7

What are some of the causes of Cataracts in Children?

Answer 7

• Congenital/ develop during childhood
• Inherited (autosomal dominant)
• Systemic disease ( Intrauterine infections (rubella), Metabolic syndromes (fabry disease), Craniofacial syndromes (Crouzon syndrome)
• Idiopathic

Question 8

What is the classification of Cataracts?

Answer 8

• There are different types of cataracts depending on the location of the lens affected
• Nuclear: primarily involves the central nucleus of the lens. Clinically there is central opacification, significant loss of colour and slow progression
• Cortical: primarily involves the cortex of the lens. Less degradation of vision and slow progression
• Posterior subcapsular: involves the subcapsular cortex. Causes disabling glare to bright lights and has a quicker progression. Linked to diabetes mellitus and corticosteroid use

Question 9

What is the lens made up of? What key function does the lens carry?

Answer 9

• The lens is composed of the soluble protein crystallin.
• This protein is important in the refraction of light
• The lens has a unique and highly organised structure. The tight packing of proteins are important for its transparency
• Transparency can be lost due to the process of normal ageing

Question 10

Why is the lens susceptible to damage? What is the Pathophysiology of cataracts?

Answer 10

• due to the lack of blood supply, containment within a capsule and inability to shed non-viable cells
• this means the lens is susceptible to damage from normal ageing and environmental insults
• This contributes to the loss of transparency as the central nucleus may become compressed, hardened and undergo nuclear sclerosis which is seen clinically as opacification.
• Light is therefore unable to be refracted onto the retina to enable vision.

Question 11

What are the clinical features of cataracts?

Answer 11

• Painless loss of vision
• blurred vision
• poor night vision
• sensitivity to light and glare
• seeing halos around lights
• polyopia: refers to visualising multiple images
• reduction in colour intensity: mainly noticed in blues
• Changes to glasses prescription

Question 12

What is myopic shift?

Answer 12

• With increasing opacification there may be an improvement in nearsightedness, but deterioration in longsightedness.
• This is due to the effect of the opacification on the refractive power of the lens

Question 13

What are the signs of Cataracts?

Answer 13

• Reduced Visual Acuity
• Loss of red reflex
• White/grey pupil
• Nystagmus

Question 14

How do you make a diagnosis of cataracts?

Answer 14

• Clinical diagnosis
• direct ophthalmoscope or slit-lamp
• Findings:
  1. loss/darkening of the red reflex
  2. Opacification seen within the red reflex
  3. Obscurantism of ocular detail

Question 15

What are the differential diagnosis for Cataracts?

Answer 15

• Refractive error
• Corneal disease
• Presbyopia
• Age-related macular degeneration
• Open angle glaucoma
• Retinopathy
• Uveitis
• Inherited eye disorders (retinitis pigmentosa)

Question 16

What is the management for cataracts?

Answer 16

• surgical replacement of the disease lens

Question 17

What are the 2 main techniques for cataract surgery?

Answer 17

• Phacoemulsification
• Standard extracapsular cataract extraction

Question 18

What are complications of Cataract?

Answer 18

• Endophthalmitis: bacterial or fungal infection of the intra-ocular fluid
• Corneal Oedema
• Cystoid macular oedema
• Malposition of the lens
• Posterior capsule rupture
• Toxic anterior Segment syndrome: inflammatory response to non-infectious containments of equipment or solutions
• Hemorrhagic Occlusive Retinal Vasculitis: HORV: associated with use of intra-ocular vancomycin

Question 19

What are some of the delayed complications of Cataracts?

Answer 19

• Retinal detachment
• Macular degeneration
• Posterior capsule opacification