Gonioscopy is Essential for Asymptomatic Patients with Family History of Glaucoma
Yes, gonioscopy is a mandatory component of the comprehensive glaucoma evaluation for asymptomatic patients with a family history of glaucoma, as it is required to differentiate open-angle from angle-closure glaucoma and to detect secondary mechanisms of elevated intraocular pressure. 1
Why Gonioscopy Cannot Be Omitted
Gonioscopy is explicitly listed as a required element of the physical examination in the comprehensive glaucoma suspect evaluation by the American Academy of Ophthalmology. 1 This is not optional—it must be performed to:
- Distinguish between open-angle and angle-closure mechanisms, which have completely different treatment approaches and prognoses 1
- Identify secondary causes of elevated IOP including pseudoexfoliation material, pigment dispersion syndrome with iris transillumination defects, iris neovascularization, or inflammatory changes 1
- Detect narrow angles or shallow peripheral anterior chamber depth that may predispose to angle-closure glaucoma 1
Family History Qualifies Patients for Comprehensive Screening
Patients with a family history of glaucoma qualify for Medicare-covered comprehensive glaucoma screening regardless of age, reflecting the substantial risk this factor confers. 2 The American Academy of Ophthalmology specifically identifies family history as a major risk factor warranting full evaluation. 1
- First-degree relatives of glaucoma patients have 9.2-fold higher odds of having primary open-angle glaucoma 1
- The severity and outcome of glaucoma in family members, including visual loss history, must be documented during initial evaluation to properly stratify risk 1
Complete Evaluation Components Required
The comprehensive initial glaucoma suspect evaluation for patients with family history must include all of the following physical examination elements 1:
- Visual acuity measurement (distance and near) 1
- Pupil examination for reactivity and relative afferent pupillary defect 1
- Slit-lamp biomicroscopy of the anterior segment 1
- Intraocular pressure measurement (preferably Goldmann applanation tonometry) performed BEFORE gonioscopy or pupil dilation 1
- Gonioscopy 1
- Optic nerve head and retinal nerve fiber layer examination through dilated pupils 1
- Fundus examination 1
Diagnostic Testing Beyond Physical Examination
After the physical examination including gonioscopy, additional diagnostic testing is required 1:
- Central corneal thickness measurement to properly interpret IOP readings and stratify risk (thinner corneas <555 μm confer higher risk) 1
- Visual field evaluation using automated perimetry 1
- Optic nerve head, retinal nerve fiber layer, and macular imaging using optical coherence tomography or other modalities 1
Critical Pitfall to Avoid
Do not rely solely on IOP measurement or optic nerve examination without gonioscopy. 1 Half of glaucoma patients have IOP below 22 mmHg, and structural changes may precede visual field defects. 1, 3 Without gonioscopy, you cannot determine the mechanism of disease or rule out angle-closure risk, which has particularly poor prognosis if untreated (18% of eyes becoming blind within 4-10 years). 2
Timing Considerations
The evaluation may require more than one visit to complete all components including additional IOP measurements at different times of day, gonioscopy, central corneal thickness determination, visual field assessment, and imaging. 1