OCULAR HYPERTENSION-----Decisions On Treatment And Review Of

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OCULAR HYPERTENSION--------------------------Dec
isions On Treatment And Review Of The Ocular
Hypertension Treatment Study

• Ophthalmology Grand Rounds
• January 18, 2006
• Brett Williams, PGY4

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OCULAR HYPERTENSION

• CASE 1
• 85 y.o. male
• IOP 26
• C/D 0.6
• HVF normal
• CCT 580

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OCULAR HYPERTENSION

• CASE 2
• 40 y.o. female
• IOP 27
• C/D 0.3
• HVF normal
• CCT 610

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OCULAR HYPERTENSION

• CASE 3
• 55 y.o. male
• African descent
• IOP 23
• C/D 0.4
• HVF normal
• CCT 498

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OCULAR HYPERTENSION

• Definition
• An intraocular pressure greater than 21 mm Hg in
  one or both eyes as measured by applanation
  tonometry on 2 or more occasions
• No glaucomatous defects on visual field testing
• Normal appearance of the optic disc and nerve
  fiber layer
• Open angles on gonioscopy, with no history of
  angle closure
• Absence of any ocular disease contributing to the
  elevation of pressure

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OCULAR HYPERTENSION

• Epidemiology
• OHT incidence 10-15 times higher than POAG
• Estimated that 4-10 of population have IOPgt21
  without disc damage/VF loss
• POAG is second leading cause of irreversible
  blindness in U.S. (AMD is 1)
• No sex predilection males may be more
  susceptible to glaucomatous damage
• Increased incidence with age gt 40 y.o.

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OCULAR HYPERTENSION
OHT
IOPgt30
IOP 24-29
IOPlt 24
OBSERVE
???
Rx
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OCULAR HYPERTENSION
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OCULAR HYPERTENSION

• Arguments for Early Rx
• IOP variability
• Significant diurnal variation may mask true
  maximum IOP and delay treatment of early damage
• No equivalent to Holter monitor for IOP
• Early damage detection
• Currently no reliable method to detect the
  earliest damage prior to ON/VF changes
• Up to 50 nerve fibre loss may occur before VF
  changes detected
• Therefore, treat all patients until reliable test
  for early damage is available

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OCULAR HYPERTENSION

• Arguments for Early Rx
• Unpredictability
• Impossible to predict which patients will convert
  to frank POAG
• Worthwhile treating 20 pts to protect one
• Corneal variability
• Corneas of different individuals may have
  different mechanical properties
• True IOP may be significantly different in 2
  patients with the same CCT
• No test of individual corneal mechanics to
  estimate true IOP available in clinical practice

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OCULAR HYPERTENSION

• Arguments Against Early Rx
• Low risk of glaucoma in OHT
• Only 1 in 10 OHT pts develop POAG in 5 years
• Risk for significant VA loss also relatively low
• Cost
• NNT 20
• Treating 20 patients to prevent 1 from developing
  early glaucoma is not cost-effective (avg. cost
  to treat glaucoma 50/month)
• More cost-effective to observe until early
  changes develop

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OCULAR HYPERTENSION

• Arguments Against Early Rx
• Treatment Risks
• Treating patients who may never develop glaucoma
  may result in unnecessary burden and side-effects
• Risk factors
• Recent research (OHTS) has defined risk factors
  for development of POAG in OHT pts
• Provides a better framework for decision making
  in OHT
• Therefore, treatment decisions should be
  individualized based on risk factors and
  individual patient characteristics

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OCULAR HYPERTENSION TREATMENT STUDY

• Introduction
• Multi-center, prospective, randomized trial
• Evaluate safety and efficacy of topical ocular
  hypotensive medications in preventing or delaying
  the onset of visual field loss and/or optic nerve
  damage in ocular hypertensive individuals at risk
  of POAG
• Inclusion criteria
• Untreated IOP 24 32 in one eye and 21 32 in
  fellow eye
• Normal HVF, Normal optic nerves
• Primary Outcome
• Development of POAG in one or both eyes
• Reproducible VF defect (x3) or glaucomatous disc
  changes (committee)

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OCULAR HYPERTENSION TREATMENT STUDY

• Methods
• 1636 subjects randomized to observation or
  topical Rx to reduce IOP by gt20 from baseline
• CCT measured for 82 of participants
• Examined every 6/12 with 30-2 HVF, disc photos
• 5 year follow-up

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OCULAR HYPERTENSION TREATMENT STUDY

• Results
• IOP reduction of 22.5 in Rx group vs. 4.0 in
  observation group
• Probability of POAG
• Rx group 4.4
• Observation group 9.5
• Therefore, 50 reduction in risk of POAG with
  treatment

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OCULAR HYPERTENSION TREATMENT STUDY

• Risk factors
• Univariate analysis
• IOP
• Older age
• Race (African American)
• C/D ratio horiz.and vert.
• Pattern std deviation
• CCT
• Heart disease

• Risk factors
• Multivariate analysis
• IOP
• Older age
• C/D ratio horiz.and vert.
• Pattern std deviation
• CCT

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OCULAR HYPERTENSION TREATMENT STUDY
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OCULAR HYPERTENSION TREATMENT STUDY

• Central Corneal Thickness
• OHTS patients have thicker corneas, on average,
  than the general population
• Pts who developed POAG had thinner corneas (553.1
  vs. 574.3)
• Patients with thinnest corneas had greater risk
  of developing POAG, especially with higher IOP
• Patients with CCT lt 555 had 3-fold greater risk
  of developing POAG compared with pts with CCT gt
  588

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OCULAR HYPERTENSION TREATMENT STUDY
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OCULAR HYPERTENSION TREATMENT STUDY

• What does OHTS Tell Us?
• Reducing IOP reduces the incidence of glaucoma in
  OHT (relative risk reduction 54)
• Risk factors for POAG include age, IOP, C/D
  ratio, PSD and CCT
• African Americans have thinner corneas than white
  patients

• Unanswered questions
• How many patients will convert w/o Rx?
• Will all patients convert eventually?
• What is the risk of long-term VA loss in
  untreated converters?
• Is it better to treat early or watch until POAG
  develops?

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OCULAR HYPERTENSION
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OCULAR HYPERTENSION
TREATMENT DECISION
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OCULAR HYPERTENSION

• Future Directions
• Imaging Modalities
• OCT/HRT as methods improve for detecting early
  optic nerve changes, these modalities may be used
  to help predict patients who will convert to POAG
• Functional tests
• Frequency doubling perimetry may be used to
  detect visual field abnormalities prior to
  standard perimetry

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OCULAR HYPERTENSION

• Future Directions
• Predictive models
• Medeiros, FA et al. (2005)
• Scoring system to predict risk of developing POAG
  in pts with OHT
• Point system derived from risk factors identified
  in OHTS
• Age, IOP, CCT, Vertical C/D, PSD
• Diabetes is a protective factor

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OCULAR HYPERTENSION

• Future Directions
• Predictive models
• S.T.A.R - Scoring Tool for Assessing Risk
• Medeiros model recently utilized by Pfizer to
  develop a clinical scoring tool
• Utilizes risk factors from OHTS to predict a
  patients risk of converting within 5 years

S.T.A.R. Treatment Threshold
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OCULAR HYPERTENSION
Scoring system
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OCULAR HYPERTENSION

• Sample Case
• 62 year old male
• IOP 27 mm Hg
• PSD 1.60 dB
• CCT 510 m
• C/D ratio 0.5
• No diabetes
• 5 Year Risk

31-40
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THANK YOU