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.