Review Article

Role of 24-Hour Intraocular Pressure Monitoring in Glaucoma Management

Table 1

Summary of 24-hour IOP patterns in normal individuals and different glaucoma types and the potential progression-predicting IOP parameters in different glaucoma types.

Patient groups24-hour IOP rhythmMean IOP (mmHg)Short-term IOPf (mmHg)Potential progression-predicting parametersOther IOP characteristics

Normal controlSpikes upon waking [34], peaks in the morning and early afternoon, troughs in the afternoon and at night [6, 19, 33]14.7 ± 2.8 [32]4–6 [9]

Primary open-angle glaucoma (POAG)Highest in the morning [19, 59], gradually decreases over the day, and lowest by midnight [17] with more frequent morning peaks (esp. 12 a.m. to 6 a.m.) [57]17.6 ± 3.2 [58]; 19.9 ± 4.3 [57]8.31 ± 2.58 [6, 19, 39]; 9.1 ± 3.6 [57]Short-term IOPf and long-term IOPf [19, 33, 43, 44, 51, 58, 6365], number of long peaks [1, 48], mean peak ratio [1, 48]Peak IOP in 73.5% of patients was outside working hours [57]

Secondary open-angle glaucoma (e.g. XFG)Pressure peak in the afternoon [44, 61]20.3 ± 3.9 [60]Greater than POAG (>15 in 35% of XFG and 7.5% of POAG) [19, 36]Mean IOP [43], short-term IOPf [43]Peak IOP in 45% of untreated XFG was outside working hours [33, 36], XFG exhibits greater peak and trough IOP than POAG [19, 36, 62]

Normal tension glaucoma (NTG)Either diurnal or nocturnal pressure spike [68, 69], peak IOP in nocturnal hours in more than half of patients [66, 70]11.5 ± 2.4 [66]; 17.8 ± 1.6 [67]4.4 ± 1.6 [6]Short-term IOPf [51, 71], long-term IOPf [6, 80], mean IOP [54, 68], minimal IOP value [54, 68]

Primary angle closure glaucoma (PACG)Highest in the morning, gradually decreases over the day, and lowest by midnight [39]29.9–45.8 [72]7.69 ± 3.03 (PACG following iridotomy) [39]Short-term IOPf [73, 74]Mean trough IOP and mean midnight IOP levels are higher in PACG than in POAG [17], degree of diurnal IOP fluctuation: PACG > PAC > PACS [73]

Ocular hypertension (OHT)Decreases during the day and increases at night time with peaks at midnight [75]21.1–24.2 [75]6–8 [19, 35, 37, 76]; 6.8 [59]Mean IOP [54, 78, 79, 81], peak IOP [54, 78, 79, 81], short-term IOPf [78], long-term IOPf [53]

IOPf: IOP fluctuation; XFG: exfoliation glaucoma.