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Cataracts and Cataract Surgery
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| Cataracts are lens opacities that can range in severity from unnoticed dots to total fogging. |
16 million people worldwide have cataracts; it is the most common cause of reversible loss of useful vision.
Incidence
- 200,000 cataract removals in the UK per annum.1
- Congenital cataract occurs in 3/10,000 population cumulatively over 5 years.2
Age is a major factor in cataract development. The Framingham eye study reported 492 cases per 100,000 in those aged >80 years.3
Risk factors
- Diabetes
- Eye trauma
- Uveitis
- Long term steroid use
- Smoking
- UV exposure
- Metabolic disorders e.g. galactosaemia in children
Three types of age related cataracts occur:
- Nuclear sclerosis; this cataract is formed by new layers of fibre (added with ageing) compressing the lens nucleus.
- Cortical; new fibres are added to outside of lens, which age and produce cortical spokes. These may not produce symptoms unless on visual axis or entire cortex is affected when it is "mature".
- Posterior subcapsular; opacities in the central posterior cortex. This may occur in younger patients and may cause glare ± deterioration in near vision.
The most common cause of congenital cataract is infection; rubella (the most common), rubeola, chickenpox, cytomegalovirus, herpes simplex, herpes zoster, poliomyelitis, influenza, Epstein-Barr virus, syphilis and toxoplasmosis. Other causes are metabolic and genetic syndromes.
This depends upon the size and location of the opacity and whether one or both eyes are affected.
Typical symptoms are:
|
Signs:
- Opacities can be seen as defects in the red reflex obtained when the ophthalmoscope is held 60 cm from the eye. This is best seen with a dilated pupil.
- Lens may appear brown or white when a bright light is shone on the eye.
Check that:
- Visual acuity is not improved by viewing test through pinhole.
- Patient can indicate where a light is placed.
- Pupillary reactions are normal.
In older patients with undemanding visual needs, it may be enough to recommend the use of a strong reading light placed above and behind the patient.
Phacoemulsification
This is the most widely used, safest and most effective technique. There is no absolute threshold of visual acuity at which surgery is indicated.4 It all depends upon the impact of the cataract on the patient's quality of life. Now no longer need to wait for the cataract to "ripen" so that contents are liquid and can be easily aspirated.

- Incision approximately 3 mm in diameter is made in the sclera.
- Round hole of approximately 5 mm diameter is made in lens capsule.
- Hard lens nucleus is liquefied by ultrasonic probe inserted through the hole and extracted.
- Soft lens fibres are aspirated.
- Replacement lens is placed folded into the now empty capsular bag where it unfolds.
- Hole heals without sutures.
This can be performed on day-case basis either with a locally injected anaesthetic or even anaesthetic eye drops. Post-operative care includes use of topical antibiotics and steroids with avoidance of strenuous activity.
A technique now reserved for specific situations is the intracapsular method where the whole lens is extracted in its capsule. In this technique, which has been used widely in the past, very thick glasses are required as no intraocular lens is present. These cause significant visual problems including objects being apparently nearer than they really are, loss of visual field and a ring of blindness. Contact lenses are better but can be a problem with the elderly. Multi-focal (non-accommodative) intraocular lenses can be implanted during surgery and provide good vision.5
Early complications
- Posterior capsule rupture (most common - approximately 3%).
- Trauma to iris.
- Wound gape or prolapse of iris.
- Anterior chamber haemorrhage.
- Rupture of lens capsule with loss of vitreous.
- Vitreous haemorrhage.
- Choroidal haemorrhage.
- Hypopyon (least common).
- Post-operative infection (endophthalmitis) occurs in around 0.13% of cases, presenting with red eye and loss of vision. Occasionally low grade infection presents late with refractory uveitis. This can be avoided by intraoperative antibiotic prophylaxis.8
Late complications
- Posterior capsule opacification - is a late complication in 20%. Most common finding.
- Cystoid macular oedema (more frequently diagnosed by angiography).
- Uveitis.
- Retinal detachment.
- Open angle glaucoma.
- Closed angle glaucoma.
- Bullous keratopathy (a rare complication).
- Increased risk of age-related macular degeneration requiring photodynamic therapy.9
Thickening of the lens capsule frequently occurs over time causing gradual deterioration of vision. This is treated by splitting the capsule with a laser.
95% of patients with otherwise healthy eyes achieve post-operative corrected acuity of 6/12.1 Diabetic retinopathy and diabetes are the major risk factors that affect prognosis.10
Document references
- Desai P, Minassian DC, Reidy A; National cataract surgery survey 1997-8: a report of the results of the clinical outcomes. Br J Ophthalmol. 1999 Dec;83(12):1336-40. [abstract]
- Rahi JS, Dezateux C; Measuring and interpreting the incidence of congenital ocular anomalies: lessons from a national study of congenital cataract in the UK. Invest Ophthalmol Vis Sci. 2001 Jun;42(7):1444-8. [abstract]
- Kahn HA, Leibowitz HM, Ganley JP, et al; The Framingham Eye Study. I. Outline and major prevalence findings. Am J Epidemiol. 1977 Jul;106(1):17-32. [abstract]
- Desai P, Reidy A, Minassian DC; Profile of patients presenting for cataract surgery in the UK: national data collection. Br J Ophthalmol. 1999 Aug;83(8):893-6. [abstract]
- Implantation of multifocal (non-accommodative) intraocular lenses during cataract surgery, NICE Interventional Procedure Guidance (June 2008)
- Kamalarajah S, Silvestri G, Sharma N, et al; Surveillance of endophthalmitis following cataract surgery in the UK. Eye. 2004 Jun;18(6):580-7. [abstract]
- Asbell PA, Dualan I, Mindel J, et al; Age-related cataract. Lancet. 2005 Feb 12-18;365(9459):599-609. [abstract]
- Barry P, Seal DV, Gettinby G, et al; ESCRS study of prophylaxis of postoperative endophthalmitis after cataract surgery: Preliminary report of principal results from a European multicenter study. J Cataract Refract Surg. 2006 Mar;32(3):407-10. [abstract]
- Kaiserman I, Kaiserman N, Elhayany A, et al; Cataract surgery is associated with a higher rate of photodynamic therapy for age-related macular degeneration. Ophthalmology. 2007 Feb;114(2):278-82. [abstract]
- Ocampo VV, Foster CS; Cataract, senile. eMedicine. April 2008.
Internet and further reading
- Khaw PT, Shah P, Elkington AR. ABC of Eyes, 4th edition.; BMJ Books.
- Tey A, Grant B, Harbison D, et al; Redesign and modernisation of an NHS cataract service (Fife 1997-2004): multifaceted approach. BMJ. 2007 Jan 20;334(7585):148-52. [abstract]
- Bashour MB, Menassa J; Cataract, congenital. eMedicine. October 2008.
- Cataract surgery. Having a cataract removed is one of the most common operations in the UK, with between 250,000 and 300,000 performed each year. Consultant ophthalmologist Mark Wilkins explains what's involved. A short video from NHS Choices. (September 2007)
Document ID: 1918
Document Version: 23
Document Reference: bgp875
Last Updated: 6 Jun 2009
Planned Review: 6 Jun 2011
The authors and editors of this article are employed to create accurate and up to date content reflecting reliable research evidence, guidance and best clinical practice. They are free from any commercial conflicts of interest. Find out more about updating.
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