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Editors Selection IGR 18-4

Surgical Treatment: Preopertaive IOP reduction

Comment by Tomas Grippo & Facundo Sanchez on:

71359 The 24-Hour Effects of Brinzolamide/Brimonidine Fixed Combination and Timolol on Intraocular Pressure and Ocular Perfusion Pressure, Seibold LK; DeWitt PE; Kroehl ME et al., Journal of Ocular Pharmacology and Therapeutics, 2017; 33: 161-169

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Seibold et al. performed a prospective, randomized study comparing, over a 24-hour period, the effect on IOP, heart rate (HR), blood pressure (BP) and ocular perfusion pressure (OPP) of a fixed combination of brinzolamide 1% / brimonidine 0.2% (BBFC) versus timolol 0.5% drops, in patients with ocular hypertension or OAG. The main value of this study rests on the fact that it is the first one evaluating the effect of BBFC throughout a 24-hr period, together with the assessment of systemic parameters.

We still do not fully understand the clinical impact of the lack of nocturnal hypotensive effect of some drops with concomitant alteration of other parameters like 24hr OPP on the glaucomatous process

The authors found that BBFC TID and timolol BID, both lowered IOP during the diurnal period. However, only BBFC decreased IOP overnight. Timolol had little effect on BP, while BBFC caused a significant reduction particularly in systolic BP.

Timolol also caused a greater decrease in HR. BBFC had no effect on OPP, while timolol increased it only during the diurnal period. The authors propose that the overall lack of effect on OPP of BBFC is likely related to the reduction in systolic BP. The study is well-designed and methodologically performed up to the high standards of the classic literature in the subject. It has a few limitations related to the design itself (open label), and other limitations we have still at present when evaluating IOP, like the impossibility of measuring it as a continuous variable.

Although great progress has lately been done, we still do not fully understand the clinical impact of the lack of nocturnal hypotensive effect of some drops with concomitant alteration of other parameters like 24hr OPP on the glaucomatous process. Despite that, Seibold et al.'s study adds to our understanding of what happens with these variables under the effect of BBFC throughout a 24-hr cycle, helping us build up the ground of knowledge necessary to make progress in that direction.

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