This document provides an overview of cataracts, including definition, types, risk factors, pathophysiology, presentation, management, and complications. A cataract is a clouding of the lens in the eye that impairs vision. The most common type is age-related cataract. Surgery involves removing the cloudy lens and replacing it with an intraocular lens. Potential complications include failure of the corneal incision to seal and tears in the lens capsule that allow vitreous to enter the anterior chamber.

1. Cataract
Muna Ahmed
Feb 2020

2. Overview
 Introduction
 Definition
 Types
 Pathophysiology
 Normal lens
 Cataract
 Presentation
 Symptoms
 Signs
 Management
 Surgery
 Complications

3. Introduction

4. Definition
 Lens opacity
 Impairs vision
 Can be unilateral or bilateral
 Major cause of blindness worldwide

6. Cataract in childhood
 Congenital
 Hereditary
 Maternal infection:
 Rubella
 Toxoplasmosis
 CMV
 Varicella zoster
 Syndromic
 Down’s syndrome
 Edward’s syndrome
 Patau syndrome
 Metabolic
 Galactosemia
 Wilson’s Disease

7. Risk factors in adults
 Old age
 Diabetes
 Eye trauma/disease
 Previous uveitis
 Radiation
 Steroid use
 Alcohol
 Smoking
 Dehydration
 Sunlight

8. Pathophysiology

9. Normal Lens
 Biconvex
 Colourless
 Transparent
 Non-vascular (aqueous humour
supplies nutrients and oxygen)
 Attached to zonular fibres
 Refracts light
 Power 18 dioptres
 Focuses light onto the
retina
 Controlled by ciliary
muscle contraction

11. Lens anatomy
 Cataracts can form in the
different parts of the lens
 Nuclear
 Diffuse cortical
 Subcapsular
Capsule
Cortex
Nucleus

12. Cataract
 Pathophysiology remains unclear
 Protein denaturation by oxidation disturbs structure and
creates opacity
 Loss of osmotic balance with influx of water into the lens
also contributes
 Therefore, light is not refracted uniformly and scatters over
the retina

14. Partially
opaque
Totally
opaque
Wrinkled
capsule
due to lysis of the
cortex
Nucleus
drops
inferiorly
within the capsule
Immature Mature Hypermature Morgagnian
Classification

15. Classification by type / location

16. Presentation

17. Symptoms
 Painless vision loss
 Reduced visual acuity both near and far vision
 Reduced colour appreciation
 Reduced contrast sensitivity
 Glare
 Change in refraction
 Ghosting
 Polyplopia
 Unilocular diplopia
 Diplopia continues when one eye is covered

18. Signs
 Early
 Indistinct appearance
when examining
retina
 Dim red reflex
 Late
 Unable to visualise
retina
 Absent red reflex

19. Rare signs
 Increased IOP
 Large cataract can cause anterior bowing of the iris, causing angle closure
 Hypermature cataract can lose protein through the (intact) anterior capsule, which obstructs the
trabecular meshwork
 Both can lead to IOP and glaucoma
 Uveitis
 Traumatic capsular rupture can release lens protein, causing an inflammatory response

20. Management

21. Surgery
 Effective
 Safe
 No proven medical treatment

22. Indication for surgery
 Cataract is causing significant visual
impairment, compromising lifestyle
 Poor visual acuity when corrected

23. Principles of surgery
 Corneal section
 Paracentesis
 Capsulorhexis
 Hydrodissection
 Phacoemulsification
 Insert IOL
 Seal wound
 After-care

24. Corneal section
 Self healing incision is made in the peripheral
cornea
Incision site

25. Paracentesis
 Aqueous will leak out of the incision, making the
anterior chamber shallow
 Viscoelastic is injected into the anterior
chamber, restoring its normal depth
 This is done via a second smaller incision

26. Capsulorhexis
 An opening is formed in the central part of the anterior
lens capsule
 This gives access to the lens cortex
 By maintaining the peripheral part of the capsule, the
capsule remains attached to the zonules, and an IOL
can be placed in the empty capsule later

27. Hydrodissection
 A needle is inserted into the soft cortex
 Balanced salt solution (BSS) is injected
between the cortex and the capsule
 BSS is specifically made to match the osmolarity/pH of
aqueous humour
 This strips the cortex away from the capsule

28. Hydrodissection
Capsule
Cortex
Nucleus
 A needle is inserted into the soft
cortex
 Balanced salt solution (BSS) is
injected between the cortex and
the capsule
 This strips the cortex away from
the capsule
BSS

29. Phacoemulsification
 The phaco handpiece has a bevelled tip which
oscillates
 This emulsifies the lens matter
 The phaco has a suction port to remove lens
matter, and an irrigation sleeve which maintains
the eye pressure

30. Irrigation/aspiration (I/A)
 This step removes any remaining debris from
the capsule including the epinucleus (soft
continuous cortex surrounding the nucleus)

31. Insertion of IOL
 The correct IOL is loaded into the cartridge, and
injected into the capsule
 The IOL will unfold. Both haptics should be in
the capsule

32. Seal wound
 The wound is sealed by ‘stromal hydration’
 This is done by injecting BSS into the corneal
incision which causes the cornea to swell and
self-seal


33. After-care
 The eye is covered with gauze and a patch is applied over the eye
 Patients are advised not to rub the eye as this can impair healing
 Antibiotic eye drops are prescribed
 Watering, gritty sensation, blurred vision and red eye can be observed
 Patients are advised not to drive or fly until seen in follow-up clinic


34. Complications
 Corneal section may not self seal if too long
 Capsulorhexis done incorrectly can cause the tear to reach the posterior capsule
 Phacoemulsification may also cause a tear in the posterior capsule
 If the capsule is unstable, the lens can drop into the vitreous. Vitreous can enter the anterior chamber
 Posterior capsule opacification may occur, this can be treated with laser