Session Title: Refractive Surgery Practice Styles
First Author: A. Illarionova Russian Federation
Co. Authors : K. KotliarAbstract Details:
Corneal tonometry has limitations when using after keratorefractive surgery. Modern transpalpebral scleral tonometry is not directly influenced by corneal surgery and it has been shown to provide reliable IOP-measurement results. The purpose of the study was to evaluate the clinical use and the reliability of modern transpalpebral scleral tonometry in patients with refraction anomaly before and after keratophotorefractive surgery
Department of Ophthalmology, Clinic 1 of President’s Administrative Department, Moscow
97 individuals (age range: 18 - 53 years) with ametropia of different grades were included in the retrospective study. 59 subjects (age range: 19 – 53 years) from this cohort had no history of keratophotorefractive interventions. Other 38 subjects (age: 18 – 50) underwent excimer laser correction of vision (Epi-LASIK, LASIK or PRK) with different durations of post-surgery period from 7 days to 4 years. IOP was assessed first with transpalpebral tonometry (Diaton transpalpebral scleral tonometer) in both eyes of each patient. Goldmann Applanation Tonometry (GAT) examination under the local anesthesia was performed thereafter in both eyes.
Individuals unaffected by surgical intervention showed GAT IOP of 18.0 (15.0;19.0) mmHg [median(1st quartile; 3rd quartile], CCT corrected GAT IOP of 17.2 (14.9;18.4) mmHg and transpalpebral IOP of 14.5 (12.5;16.0) mmHg. In patients underwent keratophotorefractive correction GAT IOP amounted to 11.8 (10.0;14.0) mmHg, CCT corrected GAT IOP was 14.3 (12.8;16.3) mmHg and transpalpebral IOP was 15.0 (13.4;17.5) mmHg. GAT IOP showed strong correlation with CCT: r=0.606; p<0.001 (Spearman), while both CCT corrected GAT IOP (r=0.095; p=0.355) and transpalpebral IOP (r=-0.125; p=0.224) did not correlate with CCT in the whole group. Bland-Altman plots show a good agreement between CCT corrected GAT and transpalpebral IOP-values.
Transpalpebral scleral tonometry results were independent from biomechanical properties of cornea, while GAT showed dependence of IOP-measurement on these properties. Even CCT corrected GAT IOP values before and after corneal surgery differ a lot from each other, while Diaton tonometry values remain stable. Since both subgroups were well comparable because of their biometric characteristic, it is not expected that IOP would decrease after surgical thinning of the cornea. In the whole group CCT corrected GAT and transpalpebral IOP-values were in a good agreement. This study confirms the reliability and advantages of the clinical application of transpalpebral tonometry after photorefractive surgery. FINANCIAL DISCLOSURE: NONE