No significant differences in keratometry measurements in patients with, without dry eye
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Key takeaways:
- There were no significant differences in keratometry measurements between patients with and without dry eye.
- Hyperosmolarity and tear film breakup time affected variability only with a reflection-based biometer.
Researchers found no significant differences in keratometry measurements before cataract surgery among patients with dry eye disease vs. those without, according to a study conducted in Norway and published in Clinical Ophthalmology.
“The primary objective of this study was to assess whether the variability in anterior keratometry measurements from three different optical biometers was higher in patients with dry eyes compared to patients with non-dry eyes,” Christian Nilsen, MD, an ophthalmologist at Ifocus Eye Clinic in Haugesund, Norway, and colleagues wrote. “The secondary objective was to investigate which separate signs of dry eyes affected the biometric measurements.”
The study was part of a prospective, interventional, randomized control trial, in which 131 patients scheduled for cataract surgery were recruited at a private eye clinic from August 2022 to May 2023. Researchers examined patients for signs of dry eye (SDE) and divided them into SDE-positive (n = 89; mean age, 75.6 years; 65.2% women) and SDE-negative groups (n = 42; mean age, 74.4 years; 66.7% women).
In addition, researchers obtained keratometry measurements using Anterion (Heidelberg Engineering GmbH; OCT), Eyestar 900 (Haag-Streit AG; combined OCT and reflection-based) and Lenstar 900 (Haag-Streit AG; reflection-based) optical biometers. Two measurements were taken with each device, with 10 to 20 minutes of waiting time between measurements.
According to results, there were no significant differences in keratometry measurements between SDE-positive and SDE-negative groups.
The researchers reported that variability of astigmatism was significantly higher among patients with hyperosmolarity vs. normal eyes for the Lenstar biometer, as was the percentage of eyes with variability of astigmatism greater than 0.25 D.
Further, the percentage of eyes with variability of average keratometry greater than 0.25 D was significantly higher among patients with positive noninvasive keratographic breakup time (< 10 seconds) vs. normal eyes for the Lenstar biometer.
“Results in the current study suggest dry eye does not materially affect surgical planning, with the exception that in some dry eye patients, reflection-based keratometry seemed slightly less reliable,” Nilsen and colleagues wrote.
Perspective
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One of the most fulfilling moments in eye care is when patients are happy with their vision after cataract surgery. More than ever, patients have high expectations for postoperative results, especially if they opt for premium IOLs.
It makes sense that reflection-based keratometry results were more affected by dryness compared with methods with OCT optical biometry due to the difference in imaging methods. However, it is important to note that there was a significant waiting period between machines while measuring, which may have affected tear film stability. Overall, it is reassuring that the effects of dryness may be mitigated with newer imaging methods that are affected less by tear film instability.
Unfortunately for most of our patients, the battle against dry eye is often a marathon, not a sprint. Minimizing preoperative dry eye can reduce the chance of symptomatic flareups and prolonged periods of punctate keratitis in the postoperative period. Furthermore, even with accurate biometry, dryness can interfere with the optics of multifocal and extended depth of focus lenses, creating unsatisfactory results for patients who opt for premium IOLs.
Ongoing dry eye management before and after cataract surgery is still essential for long-term patient satisfaction with postoperative results.
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