ANALYSIS OF RESULTS OF BIDIRECTIONAL CORNEAL APPLICATION AND ELECTRON TONOGRAPHY IN PATIENTS AFTER VITRECTOMY

Purpose: to analysis of the results of bidirectional corneal applanation and electron tonography in patients after vitrectomy and to tormulate practical recommendations on the research results.

Patients and methods. 96 patients (96 eyes) with epiretinal fibrosis (37%) and idiopathic macular orifice (63%) were examined. Bidirectional corneal applanation (ORA) and electron tonography were used to determine the intraocular pressure. The main criteria for selection in the study groups were absence of traction retina detachment, the implementation of transciliary vitrectomy without use of silicone oil tamponade, no need for intra- and postoperative panretinal lacer coagulation were. All subjects had emmetropic refraction. Patients didn’t reserved instillations of corticosteroids, because corticosteroids lead to iatrogenic effects on the hydrodynamic parameters in the postoperative period.

Results. According to electronic tonography in the postoperative period, an increase in IOP by 10%, intraocular fluid production by 53% was noted. According to the ORA, the increase in corneal-compensated pressure was 20%. A statistically significant decrease in corneal hysteresis was also detected in 7%. According to both methods of IOP, similar trends in its changes after removal of the vitreous body were obtained. Vitrectomy is accompanied not only by an increase in IOP, but also by a change in the biomechanical properties of the fibrous tunic, which can affect the accuracy of ophthalmotonometry. The accuracy of determining the level of IOP by electron tonography is strongly deepens on the presence of edema and the shape of the cornea, as well as biomechanical changes in the fibrous membrane of the eye after vitrectomy.

Conclusion. Bidirectional corneal applanation is a non-contact, safe method. It can be used to accurately measure IOP after vitrectomy. This method is objective, independent of the error of the operator, fast and easy to use. We consider that surgery must use IOP screening up to 6 months after the operation and refusal to use steroid drugs in the postoperative period because of the tendency to changes in hydrodynamics after vitrectomy.

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