What factors have the greatest risk for cataract surgery?

The definitive and largest review of risk factors affecting cataract surgery in the UK was published in early 2008. This was a multicentre review of 55567 operations using electronic patient records in the cataract national dataset. [1] Adverse outcomes can be separated into intraoperative and postoperative complications. (See tables below from [1])

 

POSTERIOR CAPSULE RUPTURE

The most frequently occurring intraoperative complication is posterior capsule rupture (PCR) - with or without vitreous loss. One paper in the series looked at patient risk factors to predict this outcome, using multivariate analysis. The implication would be to appropriately counsel patients at a pre-operative stage and to identify and reserve high risk cases for senior surgeons.

Significant patient and surgeon determined risk factors identified are listed below: (From paper [2]):

Risk factor

Adjusted odds ratio of PCR

Age

 

None and age under 60 years

1.00

Age 60-69 years

1.14

Age 70-79 years

1.42

Age 80-89 years

1.58

Age 90+ years

2.37

 

 

Gender

 

Female

1.00

Male

1.28

 

 

Glaucoma (type not specified)

1.30

 

 

Diabetic Retinopathy (grade not specified)

1.63

 

 

Brunescent/ white cataract

2.99

 

 

No fundal view/ vitreous opacities

2.46

 

 

Psuedoexfoliation/ phacodonesis

2.92

 

 

Pupil Size (Subjective assessment by surgeon)

 

Large

1.00

Medium

1.14

Small

1.45

 

 

Axial Length equal to or over 26mm

1.47

 

 

Use of Doxazocin

1.51

 

 

Documented inability to lie flat

1.27

 

 

Grade of Surgeon

 

Consultant

1.00

Associate Specialist

0.87

Staff Grade

0.36

Fellow

1.65

Specialist Registrar

1.60

Senior House Officer

3.73

The above odds ratios can be multiplied together to give a ‘composite’ odds ratio as described in the paper. Using the above graph this can be translated into a percentage probability of PCR. Click here for an online calculator using the above data. Why not estimate the risk for an SHO operating on a diabetic male with high myopia and a white cataract who uses Doxazocin!

As can be seen, one of the most significant risk factors is the individual surgeon. This was analysed further, confirming that increased seniority and those operating on larger numbers each year have a lower rate of PCR. [3]
ANTICOAGULATION

Another consideration covered is anticoagulation. [4] Around 28.1% of cataract patients in the UK are on Aspirin, with 5.1% and 1.9% on Warfarin and Clopidogrel respectively. Fortunately the incidence of suprachoroidal haemorrhage or hyphaema is not statistically increased with the use of any of these agents.

In relation to Warfarin, this is based on patients with an INR in the normal therapeutic range. It is widely accepted that this does not increase the risk of significant complications [5] and is reflected in the Royal College of Ophthalmologists’ cataract guidelines.

The rate of subconjunctival haemorrhage with sub-tenon and sharp needle anaesthesia is higher in patients on Clopidogrel or Warfarin, but there is no associated visual impairment. Interestingly patients on Clopidogrel alone have a statistically high risk of PCR, which remains to be explained.

Dr Colin Chu

 

REFERENCES

[1] Jaycock et al. The Cataract National Dataset electronic multicentre audit of 55 567 operations: updating benchmark standards of care in
the United Kingdom and internationally Eye (2009) 23, 38–49.

[2] Narendran et al. The Cataract National Dataset electronic multicentre audit of 55 567 operations: risk stratification for posterior capsule rupture and vitreous loss. Eye (2009) 23, 31–37.

[3] Johnston et al. The Cataract National Dataset Electronic Multi-centre Audit of 55 567 Operations: variation in posterior capsule rupture rates between surgeons. Eye 2009 Aug 14. [Epub ahead of print]

[4] Benzimra et al. The Cataract National Dataset electronic multicentre
audit of 55,567 operations: antiplatelet and anticoagulant medications. Eye 2009; 23(1):10-6.

[5] Konstantatos A. Anticoagulation and cataract surgery: a review of the current literature. Anaesth Intensive Care 2001; 29: 11–18.