How and where should intraocular pressure be measured after photorefractive keratectomy?

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Rao and coauthors studied the accuracy of GAT in post-PRK eyes and like us used a MacKay-Marg-like tonometer and the fellow eye measurements as controls. They also thoughtfully added IOP in the peripheral cornea as a third control.

Their main finding of an underestimation of IOP in post-PRK eyes when measured by GAT in the central cornea is similar to ours. When IOP was measured in the control eyes, Rao and coauthors found an increase in IOP values in the peripheral cornea compared with those in the central cornea (0.58 mm Hg and 1.07 mm Hg by GAT and Tono-Pen, respectively). Therefore, IOP measurement in the central cornea by Tono-Pen may be appropriate in post-PRK eyes, especially in eyes with high myopia or when topical steroids are used.