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Software upgrade improves optical biometry in eyes with severe cataracts
J Cataract Refract Surg. 2011;37(1):45-49.
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New software enhanced optical biometry and axial length measurement in eyes slated for cataract surgery, a study found.
Investigators reported outcomes from version 5 software for the IOLMaster (Carl Zeiss Meditec) partial coherence interferometry device and the older version 4 software.
Whereas the algorithm in version 4 calculated axial length in millimeters on a single scan, version 5 generates a composite measurement of multiple scans that improves signal-to-noise ratio, the study authors said.
"This improvement was most noticeable in eyes with posterior subcapsular cataract, in which the proportion of measurement failures was reduced by approximately 50%," they said.
The observational analysis was undertaken in two stages. First, a prospective study included 458 eyes of 244 patients who underwent axial length measurement with version 4 software and then underwent re-measurement with version 5. A subsequent retrospective study included 2,255 eyes of 1,712 patients who underwent measurement exclusively with version 5 software.
Results of the prospective study showed that 49 eyes of 46 patients (10.6%) were unable to be measured with version 4 software because of insufficient signal-to-noise ratio. Version 5 software enabled successful measurement in 30% of those cases.
In the retrospective study, 105 eyes (4.7%) could not be measured successfully with version 5 software because of white cataract, posterior subcapsular cataract or dense nuclear cataract combined with posterior subcapsular cataract, the authors reported.