What is the recommended treatment and monitoring plan for patients with glaucoma using tonometry to manage intraocular pressure (IOP)?

Treatment and Monitoring Plan for Glaucoma Using Tonometry

The recommended treatment and monitoring plan for glaucoma patients should include regular IOP measurement with Goldmann applanation tonometry, medical therapy to lower IOP as first-line treatment, and monitoring for structural or functional changes of the optic nerve at least yearly. 1

Diagnosis and Assessment

• Diagnosis of primary open-angle glaucoma (POAG) is established by consistently elevated intraocular pressure (IOP), suspicious optic nerve, retinal nerve fiber layer (RNFL) abnormalities, or visual field defects 1
• Risk factors include older age, African or Latino/Hispanic ethnicity, elevated IOP, family history of glaucoma, lower ocular perfusion pressure, type 2 diabetes mellitus, and thin central cornea 1
• Comprehensive assessment should include:
  • Visual acuity measurement 1
  • Pupil examination for relative afferent pupillary defect 1
  • Slit-lamp biomicroscopy to identify secondary mechanisms for elevated IOP 1
  • IOP measurement preferably by Goldmann applanation tonometry 1
  • Gonioscopy to exclude angle closure or secondary causes of IOP elevation 1
  • Optic nerve head and RNFL examination 1

Tonometry Considerations

• Goldmann applanation tonometry remains the gold standard for IOP measurement 1, 2
• Central corneal thickness (CCT) affects IOP readings and should be measured, as thinner corneas may lead to underestimation of true IOP 1
• Alternative tonometry methods may be considered in specific situations:
  • Dynamic contour tonometry or pneumatonometry for patients with corneal abnormalities or post-keratorefractive surgery 1
  • Home tonometry may be beneficial for monitoring IOP fluctuations outside office hours 3, 4, 5

Treatment Approach

• The decision to treat depends on:

  • Level of IOP and associated risk factors 1
  • Evidence of optic nerve, RNFL, or visual field changes 1
  • Risk assessment based on Ocular Hypertension Treatment Study (OHTS) 1

• Medical therapy is the first-line approach for lowering IOP:

  • Prostaglandin analogs (e.g., latanoprost 0.005%) are effective for reducing elevated IOP in patients with open-angle glaucoma or ocular hypertension 6
  • Combination therapies like brimonidine/timolol can provide additional IOP reduction for patients not controlled on monotherapy 7
  • Laser trabeculoplasty should be considered when medication adherence, cost, convenience, or side effects are concerns 1

Monitoring Protocol

• Regular IOP measurements should be performed, with time of day recorded to assess diurnal variation 1
• Additional IOP measurements at different hours or on different days may be necessary to capture fluctuations 1, 5
• Optic nerve head evaluation should be performed regularly with documentation by imaging, photography, or drawing at least yearly 1
• Visual field evaluation should be performed at least yearly, with more frequent testing (three visual fields per year) during the first 2 years to detect rapid progression 1
• Consider position-dependent IOP measurements, as IOP is typically higher in the supine position, especially in glaucoma patients 8

Special Considerations

• IOP fluctuations may be greater in glaucomatous eyes than healthy eyes, with peak IOP often occurring outside office hours 5
• Home tonometry may reduce unnecessary hospital visits and provide valuable information about diurnal IOP patterns 3, 4
• Patients with thin central corneas have a higher risk of developing glaucoma and may require more aggressive treatment 1
• Nocturnal IOP measurements may be important, as some patients show significant IOP elevation during sleep 5, 8

Pitfalls and Caveats

• Relying solely on in-office IOP measurements may miss significant IOP fluctuations that occur outside office hours 4, 5
• Not accounting for central corneal thickness can lead to inaccurate IOP assessment and inappropriate treatment decisions 1
• Failure to recognize and monitor other risk factors beyond IOP may result in disease progression despite seemingly controlled IOP 1
• In the OHTS, more than 90% of patients with untreated ocular hypertension did not progress to glaucoma over 5 years, highlighting the importance of identifying those at highest risk 1