Fig 1. Mechanism and structure of our novel lens cleaning device.

A. Appearance. B. Manipulation techniques for lens cleaning started by covering the air hole with a finger. C. Schema of the device. The left panel shows that the air runs through the device without covering the hole with a finger, the middle panel shows the water cleaning initiated by air-hole covering with finger and scope, and the right panel shows that water drops on the lens surface after cleaning are removed by air aspiration through the air hole.