Fig. 8. Goldmann applanation mires. i) The tear meniscus encircling the applanated surface of the cornea (a) is stained by fluorescein dye, appearing bright green under cobalt-blue light. Prisms in the applanating cylinder convert the image of the circular meniscus into two half rings (mires) separated by 3.06 mm. ii) Too little fluorescein dye produces thin mires, which can lead to an overestimation of the intraocular pressure. iii) Too much fluorescein dye produces thick mires, which yield an underestimation of the intraocular pressure.