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Handheld keratometry readings comparable before, after anesthesia
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Handheld keratometry measurements were as reliable in patients under anesthesia as in awake patients, regardless of positioning, according to a study. However, readings trended toward being flatter in patients when muscle relaxants were used at induction.
“Corneal curvature measurements are often obtained under general anesthesia in difficult patients and children, especially to calculate intraocular lens power before cataract surgery. Knowing whether these measurements correlate well with measurements in clinic is important,” the authors said.
The prospective study included 100 eyes of 50 patients. Twenty-five patients underwent ophthalmic surgery and 25 patients underwent non-ophthalmic procedures; both groups were then divided into those receiving muscle relaxants at induction and those who did not.
Thirty-four patients with a mean age of 38.5 years who were given muscle relaxants at induction were placed in the relaxant group, and 16 patients with a mean age of 15.7 years were placed in the non-relaxant group.
The trend toward flatter measurements with use of muscle relaxants was only statistically significant in right eyes.
Mean keratometry reading was 43.00 D in the right eyes and 42.88 D for the left eyes in the relaxant group compared with 42.83 D and 43.08 D in the non-relaxant group. There was no significant differences found in measurements of the upright and supine positions in both groups.
Seventy-one percent of right eyes and 76% of left eyes in the relaxant group had differences within 0.5 D compared with 81% of right eyes and 88% of left eyes in the non-relaxant group.
Disclosure: The study authors report no relevant financial disclosures.
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