Mr CHRISTOPHER MICHAEL KNAPP - GMC Number : 4285111

Results from work at the following organisations

  • United Lincolnshire Hospitals NHS Trust

PCR result for 1 year period from 01 April 2022 to 31 March 2023

Posterior capsular rupture (PCR) is the most common complication during cataract surgery and if this happens there is an increased risk of post-operative complication.

Percentage without PCR

Overall rate 98.9%
This surgeon 98.62%
Number of operations 59
Within expected limits

Around 99 out of every 100 surgeries by all surgeons were completed without this complication.

This surgeon performed 59 cataract operations

PCR Notes

  • Posterior Capsular Rupture (PCR) is defined for the purposes of the National Audit as “rupture of the posterior capsule with or without vitreous prolapse, or zonule rupture with vitreous prolapse” and abbreviated simply as PCR. It should be noted that the definition excludes zonule dehiscence where no vitreous prolapse has occurred.
  • PCR is the most important intraoperative complication and when it occurs as defined above, there is a 6 fold increased risk of vision loss, a 40 fold increased risk of post cataract retinal detachment and an 8 fold increased risk of endophthalmitis. Although PCR as defined may occasionally be unavoidable it is generally accepted as an indicator of surgical quality.
  • Risk adjustments - to make comparisons as fair as possible, surgeons who undertake high risk cases are given appropriate credit for the complexity of their work. 

Vision Loss result for 1 year from 01 April 2022 to 31 January 2023

Vision Loss is vision which is significantly worse after the operation than before. It is measured by the sight test letter reading chart.

For cataract surgery, the most important outcome is vision; this is what matters most to patients. Vision worse after the operation is an adverse outcome. 

Avoidance of Vision loss: Despite the best efforts of NHS staff, there are risks with any surgery and some patients lose vision following cataract surgery. This is the percentage of patients who can see better after their cataract operation, or whose vision is at least maintained at a similar level.

Not enough data

Avoidance of Vision Loss notes

  • There are risks with any surgery and despite the best efforts of the surgeons and their teams, some people do lose vision as a result of cataract surgery. We count the number of people that are definitely able to read fewer letters on the eye testing chart after their surgery compared to before. We know that what people can read on the vision testing chart can vary a little day to day, so we only record someone has having definitely “lost vision” if they are reading at least two lines worse on the eye testing chart. The percentage reported here is the proportion of operations in which the eye can read more letters on the eye testing chart, or at least approximately the same. People who read one line worse on the chart after surgery are therefore included in this, but those who are reading two lines less are considered to have definitely lost some vision.
  • Centres or surgeons where less than 40% of operations have both a pre- and post-operative record of VA are not reported.
  • Visual Acuity (VA) data recording is currently not complete at most participating centres. This has been recognised as a risk for the audit from the outset and despite significant efforts to improve this, including electronic data return tools for optometrists to use, this remains an issue.

Audit Caveats and Notes

The data displayed above represents the data supplied to the National Cataract Audit which does not yet have complete national coverage for England and Wales.

Please note that we have only published the outcomes for surgeons who have performed a minimum of 50 operations during the audit period.

Not all centres submit data to the NOD. Where a surgeon works in more than one centre with not all of these submitting data to the NOD, the operations reported as having been undertaken by that surgeon may be incomplete.

  • Overall rate - is the overall expected rate used as a benchmark to provide context when interpreting a surgeon or organisation result. As with all types of 'averages', some surgeons or organisations results will be above the benchmark and some below. The expected limits take into account the number of operations undertaken by a surgeon or organisation (i.e. the sample size) and whether the rate is statistically higher or lower than might be expected for the number of operations. Small samples are associated with greater uncertainty and therefore wider limits, bigger samples have greater precision and narrower limits.
  • Within Expected Limit (with green tick) - outcome is acceptable
  • Outside Expected Limit (with red cross) - outcome is not acceptable

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