Artificial tears reduced refractive errors in cataract surgery work-up
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Dry eye syndrome significantly affected values associated with corneal astigmatism and should be considered during preoperative evaluations for patients undergoing toric IOL implantation, according to a study.
“The aim of this study was to assess the impact of the use of artificial tears during the preoperative workup for cataract surgery with toric IOL implantation,” researchers at the Desgenettes Military Hospital in Lyon, France, wrote in the Journal of Refractive Surgery. “Its impact on the assessment of corneal astigmatism, toric IOL calculation and the postoperative refractive accuracy was analyzed.”
Researchers conducted a monocentric prospective study that assessed 73 eyes of 51 patients, all of whom were included after a preoperative workup before undergoing cataract surgery with toric IOL implantation. Patients did not receive artificial tears during the workup.
Researchers then conducted a second series of examinations 1 minute after artificial tear instillation, repeating biometry with the IOLMaster 700 (Carl Zeiss Meditec AG) and topography with the OPD-Scan II (Nidek), to analyze changes in anterior corneal astigmatism and toric IOL calculation.
According to study results, anterior corneal astigmatism and total corneal astigmatism were significantly modified with the use of artificial tears before the examinations (anterior corneal astigmatism: 1.51 ± 0.57 D, range: 0.75 to –3.55 vs. 1.42 ± 0.63 D, range: 0.42-3.35 D; P = .043; total corneal astigmatism: 1.59 ± 0.54 D, range: 0.87-3.48 vs. 1.51 ± 0.59 D, range: 0.56-3.27 D; P = .038).
Artificial tear instillation also led to a change in IOL cylinder calculation in 43.8% of cases and a change in implantation axis greater than 10° in 17.7% of cases, with changes significantly greater in the subgroup of patients with a break-up time (BUT) less than 5 seconds (calculated IOL cylinder: 57.5% vs. 27.3%; P = .009; change in axis implantation greater than 10°: 27.8% vs. 6.2%; P = .029). In addition, the mean absolute error in predicted astigmatism was significantly lower after artificial tear instillation in the same subgroup (0.48 ± 0.50 D, range: 0-2.79 vs. 0.37 ± 0.25 D, range: 0-1.1 D; P = .048).
Although only 25% of patients reported symptoms of dry eye during questioning, researchers discovered dry eye syndrome — as evidenced by a BUT of less than 5 seconds — in more than half of study participants.
“Dry eye significantly changes the values of corneal astigmatism,” researchers wrote. “When taken into account, this change has a significant impact on toric IOL calculation, whether on the IOL cylinder or on the implantation axis. Using artificial tears limits refractive errors, especially when the BUT is less than 5 seconds. Therefore, it seems important to us to take dry eye into account during preoperative explorations for refractive cataract surgery.”
Perspective
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Dry eye has been, and continues to be, a major health concern globally. Unfortunately, our patients are either not receiving treatment because they are asymptomatic or noncompliant. Proactive ocular surface disease management is an extremely important consideration prior to cataract surgery.
The TORIDE study evaluated change in presurgical toric IOL calculations before and after instillation of artificial tears. It found that using artificial tears reduced the magnitude of IOL cylinder calculation in nearly half of the cases. These changes in measurement were more common in patients who had BUT of less than 5 seconds. In the study population, 54.8% of participants had tear film instability, but only 25% were symptomatic, and only 15.3% were currently treated.
This study reinforces the fact that instillation of an artificial tear prior to obtaining IOL calculations can provide a more accurate measurement. This simple and cost-effective option could improve surgical outcomes for many patients.
A few downsides of the study: It was monocentric, had a small sample size, and there was no blinding of the individuals performing the measurements, leaving opportunity for possible bias. However, the positive results warrant further investigation of the topic.
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