Target IOP Lt Col Rashed

TARGET INTRAOCULAR
PRESSURE (IOP)
LT COL A.K.M. RASHED-UL-HASAN
F.C.P.S, D.O
Long term fellow trainee (Glaucoma)

Introduction
 Glaucoma
 progressive optic neuropathy as a results of RGCs
loss
 VFL
 IOP- important risk factor & only factor that can
be modified at present time
 Reducing IOP is currently the only clinically proven
way to slow down the progression of glaucoma

 Fundamental goal-
 Slowing the rate of RGCs loss to age dependent rate
 Reduce the rate of progression of Glaucomatous
damage

Target IOP
 A “target” pressure should be set as a goal of long
term therapy.
 It should be chosen on an individual basis, weighing
potential benefits and risks of treatment for each
patient.
 Definition: “upper limit of IOP that prevents
further glaucomatous damage”
 Also called the “Ideal pressure”, “safe level of IOP”

Evidence from Clinical Studies
 Ocular Hypertension Treatment Study (OHTS)
 ≥20% reduction of IOP from initial value, leads to a
lower rate of glaucoma progression in OHT patients.
 Collaborative Initial Glaucoma Treatment Study (CIGTS)
 To determine newly dx pts with POAG are better treated
initially with medication Vs filtering Sx.
 Both lowered IOP; Sx >medication
 Glaucoma progress will be minimal if pts are treated
aggressively to achieve low target pressure.

 Early Manifest Glaucoma Trial (EMGT)
 Compare the effect of immediate t/t to lower IOP Vs
no t/t on progression of newly detected POAG.
 For every 1 mm drop in IOP
, a 10% reduction in risk
of glaucomatous progression was observed.
 Early t/t reduces & delays glaucoma progression

 Advanced Glaucoma Intervention Study (AGIS)
 Trabeculectomy Vs laser trabeculoplasty in pts
with IOP uncontrolled by medication
 Target IOP was set at <18 mmHg
 Follow-up pts with lower IOP were free from
visual field impairment.

 Collaborative Normal Tension Glaucoma Study (CNTGS)
 Effect of IOP decrease in patients with NTG or
low tension glaucoma
 ≥30% IOP reduction from base line, decrease
delayed the progression of glaucomatous lesions
by 3 years

Establishing a target IOP
Why?
When?
To maintain functional vision throughout the
patients lifetime with a minimal effect on
quality of life
On initial visit & review periodically
How? Individualized

Assessment of target IOP
 Based on an individual glaucoma risk assessment
1. Estimation of amount of glaucoma damage (opticdisc
and visual field assessment).
 If advanced optic nerve damage at the time of
diagnosis, set lower target IOP & vice versa
2.Appreciation of the damaging IOP or “maximum” IOP at
which damage has occurred.
 lower IOP at initial presentation, set lower target IOP &
vice versa

3. Life expectancy of pts.
 High expectancy, set lower the target IOP & vise versa.
4. Identification of the other risk factors for progression
(presence of a severe damage in other eye, family
history of blindness from glaucoma, high myopia,
ethnicity, vascular risk factors)
5. Assessment of the rate of progression of glaucoma
damage, i.e severity of damage that has already
occurred versus time.
6. Centre corneal thickness

Factors Set High target IOP Set Low target IOP
Initial presentation Higher IOP Lower IOP
Life expectance Shorter Longer
ONH damage Early Advanced

1. Percentage drop in IOP
2. Absolute reduction
HOW TO CALCULATE A TARGET
PRESSURE

HOW TO CALCULATE A TARGET
PRESSURE
1. IOP < 21 mm Hg
2. Lower IOP by 20%-30% from base line
3. Lower IOP by 1/3 of base line

1. Zeyen’s simpler version
Target IOP = Max IOP – Max IOP% - Z
Z = Optic nerve damage severity factor
2. CIGTS Formula
Target IOP = [1-{ ref IOP + VF score } / 100 ] x [ ref IOP ]
3. Modified Jampel Target IOP
, 1999
FORMULA TO CALCULATE
TARGET PRESSURE

Modified Jampel Target IOP
, 1999
 Ex. IP- 30 , Z- 2
 TP= 30 (1-30/100)-2 ± 2 = 19±2 mm Hg

1. MILD GLAUCOMA
Characteristics Optic Nerve abnormality
No Visual Field Abnormality
2. MODERATE GLAUCOMA
Visual Field Abnormality
in one hemi-field but not within 5° of fixation
3. SEVERE GLAUCOMA
Visual Field Abnormality
in both hemi-field and within 5° of fixation
GRADING SYSTEM BY AAO

AAO GUIDELINES: TARGET IOP
Clinical conditions Target IOP
1. Mild glaucoma Reduction of 20% from baseline /
IOP 17-18 mm of Hg
2. Moderate glaucoma Reduction of 30% from baseline/
IOP 14-16 mm of Hg
3. Advanced Glaucoma Reduction of 35-40% from
baseline / IOP 10-12 mm of Hg
4. Ocular hypertension Reduction of 20% from baseline
6. Normal pressure glaucoma or NTG Reduction of 30% from baseline

Recommended target IOPs in the
Guidelines of the European Glaucoma
Society (2003)
POAG Target IOP
Early Glaucoma <18 mm Hg
Mod Glaucoma <15 mm Hg
Adv Glaucoma <12 mm Hg
Terminal Glaucoma <10 mm Hg
NTG Target IOP
Early Glaucoma <15 mm Hg
Mod Glaucoma <12 mm Hg
Adv
Glaucoma
<10 mm Hg

HOW TO USE A TARGET
PRESSURE
 Draw an IOP curve for each glaucomatous patient
and to highlight the target pressure on the curve.
 Target pressures should be reevaluated periodically.
 10 yrs later patient may develope any new systemic
or ocular conditions that might affect the
risk/benefit ratio of therapy.

HOW TO USE A TARGET PRESSURE
cont..
 Target pressure needs to be lowered if
glaucomatous damage is progressing despite IOP’s
below the initially set target.
 Conversely, the target IOP range may have to be
increased if achieving the target IOP causes
adverse ocular or systemic side effects.

Listen to Expert
“ You’re not going to have one target pressure that’s
appropriate for every patient. It is a dynamic process
and you always have to be alert and open to
modification.”
L. Jay Katz,
Professor of Ophthalmology
Jefferson Medical College

Listen to Expert
“Patients should be followed closely over time and their
target pressures should be adjusted, depending upon
how the patient is doing. If the patient progresses, the
target pressure should be lowered. If the patient does
very well, the target might be raised.”
Stevens Simmons,
Associate Clinical Professor,
Albany Medical College

Target Intraocular Pressure
Calculator

Key Points
 IOP is a significant, modifiable risk factor in Glaucoma
 Lowering IOP to a target level is helpful across the spectrum of
ds states & IOP levels:
 Advanced glaucoma
 Normal tension glaucoma
 Newly diagnosed glaucoma
 Target IOP range must be:
 Individualized
 Re-evaluated periodically

Target IOP Lt Col Rashed

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