Importance of diurnal variation

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