Purpose: To compare intraocular pressure (IOP) measurements by the Tone-Pen
2 tonometer and Goldmann applanation tonometer (GAT) in post-photorefracti
ve keratectomy (PRK) patients.
Setting: Refractive Surgery Center, Assai Harofeh Medical Center, Zerifin,
Israel.
Methods: In 18 patients, IOP was measured by GAT and then by Tone-Pen 2 ton
ometer 2 to 18 months following PRK (mean 6.6 months +/- 5.1 [SD]). Photore
fractive keratectomy had been performed in 1 eye of each patient; the fello
w eyes served as controls. Corneal curvature and thickness were evaluated.
Ten of the 18 patients were treated with topical steroids.
Results: in the post-PRK eyes, mean GAT IOP was 1.8 +/- 3.1 mm Hg lower tha
n mean Tono-Pen IOP (P = .012); there was no significant IOP difference in
the control (fellow) eyes. in steroid-treated post-PRK eyes, mean GAT IOP (
12.2 mm Hg) was 2.2 +/- 1.3 mm Hg lower than mean Tono-Pen IOP (14.4 mm Hg)
(P = .0007). Mean Tono-Pen IOP in Steroid-treated post-PRK eyes was 4.3 +/
- 3 mm Hg higher than in the fellow eyes (P = .0014); mean GAT IOP was only
2.3 +/- 3.5 mm Hg higher (P = .04). In post-PRK eyes without topical stero
id treatment, mean GAT IOP was 2.0 +/- 1.18 mm Hg lower than in the fellow
eyes (P = .001); there was no significant difference in Tone-Pen IOP. There
was a negative correlation between the difference in IOP values (Tono-Pen
minus GAT) and corneal curvature in post-PRK eyes (r = 0.76, P = .0108, n =
15).
Conclusions: The Tono-Pen tonometer appeared to be less affected than the G
AT by the relative flattening, thinning, and anterior stromal decreased rig
idity of the central cornea that occur following PRK. Post-PRK steroid-indu
ced IOP elevation may be masked by the artifactual decrease in GAT IOP.