Thesis (M.Sc.) - Cairo University - Faculty of Medicine - Department of Ophthalmology

To compare the obtainability and values of IOP measurements by Goldmann Applanation Tonometry (GAT) and Ocular Response Analyzer (ORA) before and after penetrating keratoplasty (PKP) testing the degree of their agreement and the impact of corneal biomechanical factors on IOP measurement. Patients and Methods The study is a comparative prospective study in which patients scheduled for penetrating keratoplasty (PKP) undergo intraocular pressure measurement (IOP) using the Ocular Response Analyzer (ORA) then the Goldman applanation tonometer (GAT) one day before surgery to be repeated one month after their surgery. Results Forty patients undergoing PKP were enrolled in the study, 28 males (70%) and 12 females 30%). The mean age of patients involved is 42.8 ± 15.4, ranging between 9 and 75 years. Obtainability of ORA (92.5% of the patients) was significantly higher than GAT (60%) postoperatively (p<0.001), while no significant difference was elicited preoperatively. The mean cornea corrected IOP (IOPcc) was significantly higher than GAT and Goldmann related IOP (IOPg) both pre and postoperatively. In addition, both mean IOPcc and GAT postoperatively (19.2 ± 8.31, 15.65 ± 6.99 mmhg respectively) were significantly higher than their preoperative values (14.44 ± 7.03, 11.78 ± 4.55 mmhg respectively). Strong correlations existed between GAT and ORA measurements both pre and postoperatively. As expected the level of agreement between GAT and IOPg was higher than IOPcc. Conclusion ORA has proven to be superior to GAT in the ability to obtain reliable IOP measurements post PKP. IOPcc measurements also prooved to be relavant, independent on corneal biomechanical factors (CH and CRF) but judging the accuracy of its values needs further large scale studies.

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