Which slit lamp filter is best for observing neovascularization?

The red free filter is optimal for observing neovascularization because it enhances the visibility of blood vessels against the background of the surrounding tissue. This filter works by allowing only green light to pass through, which provides improved contrast for the red blood cells in the vessels. As a result, any new blood vessel growth, characteristic of neovascularization, becomes more pronounced, making it easier for the clinician to identify and assess the extent of this condition.

In contrast, ultraviolet filters are primarily useful for observing corneal and lens pathology but do not enhance the visibility of vascular structures. Neutral gray filters reduce overall brightness without providing the contrast necessary to discern neovascularization. Cobalt blue filters are used primarily to enhance the visibility of fluorescence when examining the cornea or other surfaces tested with fluorescein dye, making them less effective for vascular observation.