What would be the BEST choice as a trial lens for a patient with a subjective refraction of -3.00 - 2.50 x 178?

The choice of trial lens for a patient with a subjective refraction of -3.00 - 2.50 x 178 is best matched with -3.00 - 0.75 x 180. This option provides a starting point that closely approximates the spherical component of the refraction, which is -3.00 diopters, avoiding a significant undercorrection in spherical power.

This lens also includes a minor adjustment in the cylindrical component, which is a common practice in trial lens fitting. While the specified cylindrical power of -2.50 is not fully matched, reducing it to -0.75 allows for a better assessment of visual acuity while the patient adapts to the cylindrical axis. The slight alteration in the cylinder power and the alignment of the axis close to the original prescription (180 degrees) facilitates refining vision once the patient expresses their subjective preferences during the trial lens evaluation.

Trial lenses should be chosen with the aim of bringing the patient's vision as close as possible to their subjective optimal while still allowing for tuning adjustments based on their feedback. This option strikes a balance between these considerations and is aligned with common practices in optometry when addressing cylindrical corrections.