Comparison of Intraocular Pressure Fluctuations Measured by Goldmann Applanation Tonometer and Pulsatile Ocular Blood Flow Analyser

BACKGROUND Intraocular pressure (IOP) is the major known risk factor in glaucoma and the primer mover of the functional damage in glaucomatous patients but it is not a unique determinant of glaucomatous damage. Clinical assessment of glaucoma patients may not be a true reflection of overall IOP control. Evaluation of the effect of glaucoma medication is restricted by measurement of IOP as a dynamic physiological parameter. PURPOSE To compare IOP fluctuations over time using Goldmann applanation tonometry (IOPGAT) and pulsatile ocular blood flow analyzer (IOP-POBFA) under the Dorzolamide/timolol or latanoprost treatment regimes. DESIGN Prospective 1 year follow-up study. PARTICIPANTS 30 randomly chosen controlled open angle glaucoma patients (60 eyes): 16 patients (32 eyes) receiving Dorzolamide/timolol fixed combination (D/T) and 14 (28 eyes) latanoprost 0.005% treatment. MAIN OUTCOME MEASURES Changes in IOP and perfusion pressure dynamics. RESULTS THERE WAS NO STATISTICALLY SIGNIFICANT DIFFERENCE IN BASELINE IOP PARAMETERS BETWEEN STUDY GROUPS: 15.69 ± 2.02 mmHg with D/T and 16.71 ± 2.84 mmHg with latanoprost (p=0.314). Both treatment regimes were tolerated and patients were adherent to treatment. Determined a strong positive correlation between IOP-GAT and IOP-POBFA; verified over time period under particular treatment regime. After 1 year follow-up D/T and latanoprost results referred to statistically significant tachyphylaxis effect, i.e. IOP-GAT increased in 2.31mmHg with D/T (p=0.007) and 2.72 mmHg (p=0.004) with latanoprost and IOP-POBFA increased in 1.74 mmHg (p=0.026) and 3.13 mmHg (p=0.007) respectively. Multiple regression analysis revealed no important blood flow factors as predictors in the increase of IOP. CONCLUSIONS Strong positive correlation was revealed between IOP-POBFA and IOP-GAT over a time period. Observed tachyphylaxis effects after 1 year under both treatment regimes should be assessed with respect to patient compliance and persistence to treatment.