Study evaluates safety of air-puff tonometry after ICL implantation
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Noncontact air-puff tonometry is an effective method of measuring IOP after ICL implantation, but it is better avoided in cases of excessive high vault, shallow anterior chamber, narrow anterior chamber angle and soft cornea.
Implantation of the Implantable Collamer Lens (ICL, STAAR Surgical) is a safe, well-established method to correct myopia, and because ocular hypertension is one of the most commonly reported complications, IOP should always be monitored after implantation. To evaluate the safety of noncontact air-puff tonometry as a method to measure IOP, the Corvis Scheimpflug tonometer (Oculus) was used for its ability to capture the overall view of the anterior segment while undergoing deformation induced by air-puff tonometry.
Sixty-four eyes of 33 patients with myopia implanted with the ICL were included in the study.
As expected, Pentacam (Oculus) measurements showed significantly reduced anterior chamber depth (ACD), anterior chamber angle (ACA) and anterior chamber volume (ACV) at 1 day and 1 week after implantation of the lens. During noncontact tonometry, contact between the endothelium and ICL was detected in two eyes of two patients when their corneas were deformed to the highest concavity. However, the mean endothelial cell density remained unchanged.
Ridge regression analyses showed that the distance between the endothelium and iris was positively correlated with ACD but negatively correlated with vault. The distance between the endothelium and the ICL was positively correlated with ACA, ACV and stress-strain index and negatively correlated with vault. This indicates that shallow ACD, narrow ACA, low ACV, high vault and soft corneas may be major risk factors for contact between the endothelium and the ICL during IOP measurement with noncontact air-puff tonometers.
“Although there is no proof that the contact between the endothelium and the ICL poses any risk to the endothelium, we recommend evaluating the anterior segment dimensions prior to noncontact IOP measurement in extreme cases,” the authors wrote.
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