What technique is used to verify gross corneal edema with a slit lamp?

The technique used to verify gross corneal edema with a slit lamp involves observing the cornea at a 90-degree angle with the slit lamp beam and utilizing the naked eye. This method allows the clinician to see the corneal layers clearly and check for signs of edema. When the beam is positioned at this angle, it can enhance the visibility of the fluid accumulation or changes in the cornea, making it easier to assess any swelling.

Other techniques such as direct visualization under bright light and indirect illumination at a low angle may not provide the same level of detail necessary for assessing corneal edema. High magnification with backlighting can also be useful in various examinations, but for gross corneal edema specifically, the 90-degree angle method is the most effective for immediate assessment and verification. Thus, this answer aligns with the preferred clinical practices to diagnose corneal conditions effectively.