Evaluation of Anterior Segment Swept-Frequency OCT Used for Guidance in Early High Intraocular Pressure Therapy after Large Diameter Penetrating Keratoplasty

Objective: To observe the characteristics of an early high intraocular pressure angle adhesion after large-diameter penetrating keratoplasty (LDPK) using anterior segment swept-source optical coherence tomography (SS-OCT) and to evaluate the anterior segment SS-OCT forguiding the treatment of high intraocular pressureafter penetrating keratoplasty. Methods: This was a retrospective observational study. Fifteen patients (15 eyes) with high intraocular pressure (IOP) in the early stage after LDPK in the Eye Hospital of Shandong Province were selectedfrom January to June 2017. Postoperative anterior segment SS-OCT was used to record the adhesion and extent of peripheral anterior synechia. Treatment plans were then developed for the patients. The relationships between preoperative etiology, preoperative intraocular pressure, intraoperative graft size, treatment plans and adhesion angle rangewerecompared and data were analyzed using the Mann-Whitney U test and the Kruskal-Wallis H test. Results: Clear images of the chamber angle were obtained with SS-OCT from allpatients with early high intraocular pressure after LDPK. There were 10 cases of anterior chamber angle adhesion (10/15), 5 cases of nocturnal adhesion (5/15), and the average adhesion range was 42° (0~183°). There was no significant difference in the range of adhesion angle between different preoperative causes (Z=-0.072, P=0.943). Preoperative high intraocular pressure was compared with preoperative normal intraocular pressure and there was a larger angle adhesion range. The difference was statistically significant (Z=-1.935, P=0.043). Alarge area of the implant had an extended range of adhesion, and the difference was statistically significant (Z=-2.506, P=0.012). All patients were followed up until normal intraocular pressure was obtained. The range of the adhesion angle in the combined surgery group was larger than that in the drug-only group. The difference was statistically significant (Z=-3.133, P=0.002), and all of the adhesion angle ranges>180° were treated with surgery. Conclusions: Anterior segment SS-OCT examination can help to find peripheral anterior synechiain patients with early high intraocular pressure after large-diameter penetrating keratoplasty. Preoperative intraocular pressure and intraoperative graft size affects the range of peripheral anterior synechia. For peripheral anterior synechia range of more than 180°, patients should have early filtering surgery if drugs are ineffective. Key words: keratoplasty, penetrating; tomography, optical coherence; high intraocular pressure; peripheral anterior synechia