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Assessing the variability of keratometry readings in preoperative cataract patients

Poster Details

First Author: M.Sarfraz UK

Co Author(s): Z. Estephan                    

Abstract Details


Keratometry readings are an important part of IOL power calculations for prospective cataract patients. The degree of error in readings has a 1:1 ratio with post-operative refractive outcomes. There are numerous devices currently on the market to take these readings and many are operator dependant. In our department, machines varied from using Partial Coherence Interferometry (IOL Master) to traditional anterior and posterior corneal topography (Orb Scanner). We investigated the reliability of the keratometry readings we were attaining on the different devices in our department and the effect that Ocular Surface Disease (OSD) had on these measurements.


Data collected and analysed at the Ophthalmology Department in Acre Mills, Huddersfield Royal Infirmary, Calderdale and Huddersfield NHS Foundation Trust, West Yorkshire, UK.


A prospective audit was carried out at the Ophthalmology department at Huddersfield Royal infirmary over the course of 2 weeks in January 2017. All pre-operative cataract patients had their biometry measured on the IOL Master by a trained ophthalmic nurse. They then had their keratometry readings repeated using a handheld keratometer and Orb Scanner. Each patient then proceeded to have a slit-lamp examination under fluorescein. The results were then analysed and correlated against clinical guidelines produced by the Royal College of Ophthalmologists.


From the current cohort of 16 patients, 7 (44%) were male and 9 (56%) were female; average age of 74 (range 62-89). 5 patients (31%) were found to have evidence of OSD which had not previously been diagnosed in all cases. 63% of patients showed a >1D difference in mean K readings between the IOL Master and the Orb Scanner. When comparing both Interferometry devices (IOL Master + Handheld device), 69% of patients were found to have mean keratometry readings within optimal range of <0.5D and the remaining 31% were those patients who were found to have OSD.


There was found to be a large variability in readings recorded between the different devices. This could be related to the highly operator dependant nature of the different machines and has led to better staff training and education within our department. Our current practise has now changed to ensure an average of 3 measurements is used for keratometry readings. The effect of OSD on keratometry readings is well known and we should consider repeating measurements in these patients or better still to consider treating any underlying pathology before proceeding to cataract surgery to ensure the best post-operative refractive outcome.

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