Importance of diurnal variation

1. Importance Of
Diurnal Variation
Dr Samarth Mishra

2. Introduction

3. Diurnal Variation Of IOP
• 95% population: 11mmhg to 21mmhg
• Mean IOP: 15.8 ± 2.6 mmHg.
• IOP highest in early morning & lowest in late evening
• Mean amplitude of daily fluctuation in N: <5mmhg
• Variation in IOP: >5mmhg; suspicious
>8mmhg; diagnostic of glaucoma
• In 1904, Maslenikow, 1st ophthalmologist to quantitate
daily fluctuations in IOP.

4. NORMAL INDIVIDUAL
• In 1963, de Venecia and Davis studied in 115 prison
inmates with normal IOP; highest IOP at 5 AM &
midnight & range of diurnal variation 4.9 mm Hg.
• Thiel found that highest IOP occurred between 5 & 7
AM before the patients arose.
• Katavisto found highest IOP values at 8 AM.
• Drance found highest IOP at 6 AM; mean diurnal
range was 3.7 mm Hg.

6. GLAUCOMATOUS PATIENTS
• Thiel reported that IOP increased from midnight to 3
AM, reaching a peak between 3 and 7 AM.
• Drance found in untreated OAG, a peak IOP at 6 AM
& mean diurnal variation 11mmhg.
• Kitazawa and Horie’s found mean variation of IOP 16
mm Hg.

7. • Katavisto found
1. Morning rise in 20%
2. Afternoon rise in 25%
3. Biphasic rise in 55%

8. EFFECTS OF GLAUCOMA THERAPY ON THE
DIURNAL CURVE
• Drance studied 132 patients receiving "medical
therapy” whose IOP ≤19 mm Hg.
• diurnal variation: 7 to 8 mm Hg which is lower than
11 mm Hg that had been seen in untreated
glaucoma pts.
• In untreated patients 46% peaks at 6 AM and only
14% at 10 PM.
• In the treated patients only 25% peaks at 6 AM,
while 23% at 10 PM.

10. CAUSES OF THE DIURNAL VARIATIONS
A. Hormonal factors:
1. Cortisol
 peaks in the early morning 8 am & lowest level at
about midnight-4 am

11. 2. Melatonin
3. Exogenous administration of corticosteroid:
• increase in IOP in patients with OAG 4 to 8
hours after administration.

12. B. Autonomic or Humoral control of Aq flow:
 Facility of Aq humor outflow; effect small & clinically
insignificant
 Formation of Aq: due to circulating catecholamines
• Low- during sleep
• Increases during day

13. C. Mechanical factors:
1. Tension in intraocular muscle compresses globe
during contracture. e.g. sleeping
2. Accommodation with corresponding contraction of
the ciliary muscles; i.e. during sleep there is less
accommodative effort than at other times
3. Alterations in blink pattern

14. SIGNIFICANCE OF DIURNAL VARIATIONS
• Important clinical implications for glaucoma patients.
• large diurnal variation (>8mmhg): risk factor for progression
of glaucoma.
• IOP peaks over a certain level or a diurnal range in IOP above
a certain level might be DD of ocular hypertension, in absence
of visual field loss or glaucomatous cupping.
• In case of pts with NTG, a single pressure taken at a specific
time represents a HIGH or LOW points, which doesn’t
represent pts avg. pressures; important in DD of NTG.

15. • Office diurnal curve:
Checking the pressure every 1 or 2 hours from
about 8 a.m. to 6 p.m.
Useful in therapy toward peak IOP, as well as
controlling the avg. pressure during a certain
time of day.

16. THANK YOU