Twenty-four hour efficacy with the dorzolamide/timolol-fixed combination compared with the brimonidine/timolol-fixed combination in primary open-angle glaucoma

AIM

The aim of this study is to compare the 24-hour efficacy of dorzolamide/timolol-fixed combination (DTFC) and brimonidine/timolol-fixed combination (BTFC) in primary open-angle glaucoma (POAG).

METHODS

One eye each of 77 POAG patients was included in this prospective, observer-masked, crossover comparison. Following a 2-month timolol run-in period, patients had three intraocular pressure (IOP) measurements at 1000, 1200 and 1400 h while on timolol treatment. Patients showing at least a 20% IOP reduction on timolol were randomised to 3 months of therapy with DTFC or BTFC, and then were crossed over to the opposite therapy.

RESULTS

Sixty POAG patients completed the study. The mean 24-hour IOP was significantly reduced with both the fixed combinations compared with the timolol-treated diurnal IOP (P < 0.001). When the two fixed combinations were compared directly, DTFC demonstrated a lower mean 24-hour IOP level as compared with BTFC (mean difference: -0.7 mm Hg, 95% confidence interval (CI): (-1.0, -0.3), P < 0.001). At two individual time points, DTFC significantly reduced IOP more than BTFC: at 1800 h (-1.0 mm Hg, 95% CI (-1.6,-0.5), P = 0.001) and at 0200 (-0.9 mm Hg, 95% CI: (-1.4,-0.5), P = 0.001). No significant difference existed for the other time points.

CONCLUSION

Both the fixed combinations significantly reduce 24-hour IOP in POAG. DTFC provided significantly better 24-hour efficacy.

Repetition plasticity in primary auditory cortex occurs across long timescales for spectrotemporally randomized pure-tones

Repetition plasticity is a ubiquitous property of sensory systems in which repetitive sensation causes either a decrease ("repetition suppression", i.e. "adaptation") or increase ("repetition enhancement", i.e. "facilitation") in the amplitude of neural responses. Timescales of repetition plasticity for sensory neurons typically span milliseconds to tens of seconds, with longer durations for cortical vs subcortical regions. Here, we used 2-photon (2P) imaging to study repetition plasticity in mouse primary auditory cortex (A1) layer 2/3 (L2/3) during the presentation of spectrotemporally randomized pure-tone frequencies. Our study revealed subpopulations of neurons with repetition plasticity for equiprobable frequencies spaced minutes apart over a 20-minute period. We found both repetition suppression and enhancement in individual neurons and on average across populations. Each neuron tended to show repetition plasticity for 1-2 pure-tone frequencies near the neuron's best frequency. Moreover, we found correlated changes in neural response amplitude and latency across stimulus repetitions. Together, our results highlight cortical specialization for pattern recognition over long timescales in complex acoustic sequences.