Which hand tool is useful for examining the sclera to detect the presence of ocular tumors?

The transilluminator is particularly effective for examining the sclera to detect the presence of ocular tumors because it utilizes a focused beam of light that can penetrate the eye tissues. This instrument allows for the visualization of structures within the eye by providing illumination that highlights abnormalities, such as tumors, in the sclera. The transillumination technique makes it easier to differentiate between normal and abnormal tissues based on how they absorb or transmit light, thereby helping in the early detection of potential ocular tumors.

The other tools listed do not provide the same level of utility for this specific purpose. A darkfield illuminator is typically used to enhance the visibility of transparent or semi-transparent structures, mainly in microscopy rather than direct examination of the sclera. A brightfield illuminator provides general illumination, but may not offer the specialized focus needed for observing deeper structures like tumors. Similarly, optical illuminators generally serve for more conventional lighting and could lack the specific focusing capability required for examining the sclera in detail.