Purpose:
To explore the impact of supine intraocular pressure on daytimediurnal curves.
Methods:
100 consecutive patients undergoing diurnal IOP monitoring wereincluded in the study. Patients were normal tension glaucomas(NTG) or suspects (NTG suspects) showing progression or primaryopen angle glaucomas (POAG) with progression. IOP was measuredwith Goldmann applanation tonometry (GAT) at 8.30, 10.30, 12.30,14.30 and 16.30. IOP was measured in the supine position byTonopen at 12.30, after placing the patient supine for 30 minutes.IOP was then measured in sitting position with Tonopen and GAT.
Results:
Mean supine IOP at 12.30 was significantly higher (p>0.001)compared to mean IOP by both Tonopen and GAT in sitting position.There was no significant difference between mean GAT and sittingTonopen IOP at 12.30 (p>0.05).Supine IOP was increased in77% of right eyes (RE) and 82% of left eyes (LE) compared tothe sitting IOP and was more than 20% higher than sitting IOPin 29% of RE and 23% of LE. There was a strong positive correlation(p>0.001) of the percentage IOP change between the two eyes.ANOVA did not find a significant difference in the IOP changefrom sitting to supine between the ethnic groups or the POAG,NTG and NTG-suspects (p>0.05). Supine IOP gave the highestvalue of IOP (p>0.001) during the whole monitoring periodin 60% of RE and 56% of LE. "Standard" phasing caused changein diagnosis (from NTG and NTG-suspects to POAG) in 9% of patients,while supine IOP caused a further change in 12% of patients.
Conclusions:
Supine IOP is significantly higher than sitting IOP in POAG,NTG and NTG suspects undergoing phasing. Supine IOP may be usefulin the detection of hypertensive peaks.
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: prevalence/incidence