Pre-surgery topographic abnormalities

It is important to perform preoperative topography in every patient prior to cataract surgery to better understand the patient's corneal shape and to be able to better advise the patient on expected post-op outcomes. This was the key message emphasized by Dr William Trattler (Center for Excellence in Eye Care, Baptist Medical Arts Building, Miami, Florida, USA) during his presentation at the ESCRS congress in Amsterdam, The Netherlands.¹

A simple study

Using a questionnaire, corneal topography was subjectively classified as being either normal, borderline forme fruste/borderline pellucid, forme fruste keratoconus, keratoconus with pellucid pattern, superior steepening and there were also choices for patients that had previously had myopic or hyperopic LASIK or lastly with significantly irregular astigmatism.

"There were a total of 400 topographies that were interpreted and surprisingly 69.3% were graded as normal, and 30.6% were graded as abnormal," added Dr Trattler. "Now, some of these patients had previous corneal refractive surgery, so, we excluded those and there were still 25% of patients with abnormal topographies before cataract surgery."

Case examples

To illustrate his point, Dr Trattler described a couple of cases. One challenging case involved a patient who had undergone successful cataract surgery in the right eye in 2011 but came back 2 years later for cataract surgery in the left eye. However, Dr Trattler explained that after performing analysis with the IOLMaster (Carl Zeiss Meditec, Jena, Germany) the patient's keratometry had increased from an average of 43.5 to 45 in the non-operated eye. "So, this was an older patient who had developed keratoconus during the 2 year time period," he said.

In another example, a 67-year old female patient had a visually significant cataract and less than 1 D of astigmatism. "So, the question is," asserted Dr Trattler, "if you don't look at topographies, how do you know what the shape of this patient's cornea is? Is it normal or abnormal? Will the shape of the cornea have an impact on the results of cataract surgery? The only way to know is to perform topography!"

This patient had keratometry consistent with forme fruste keratoconus, explained Dr Trattler. "She may end up with 20/25 vision instead of 20/20, so it's nice to identify these sets of patients ahead of time," he added.

"You don't get clues in your IOLMaster that you should be performing topography in every patient, so unless you do perform topography you won't know what your patient's cornea looks like," he concluded.

Reference

1. W. Trattler, 'The incidence of topographic abnormalities in patients scheduled for cataract surgery', Free Paper Presentation, ESCRS 2013, Amsterdam, The Netherlands.