Glaucoma laboratory findings
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
Structural tests
- Tonometry: measuring the intraocular pressure and comparing with both population norms and with subsequent measurements over time. The Goldmann Applanation Tonometer[1] is one example.
- Fundoscopy: stereoscopically viewing the optic nerve head and the retina, looking for characteristic glaucomatous signs and for changes in appearance over time. One important observation is the optic nerve's "cup-disc ratio". Fundus photos (stereoscopic or mono) may be taken to aid the clinician. The 3Dx Digital[2] stereoscopic camera is one example.
- Pachymetry: using a variety of modalities to measure the thickness of the cornea, as a thin cornea is a risk factor for glaucoma.[3][4][5] Corneal pachymetry can also be used to calibrate the measured intraocular pressure for the patient's corneal thickness, as a thicker cornea tends to yield higher intraocular pressure readings.[6][7] The Tomey SP3000 [8] is one example.
- Scanning laser ophthalmoscopy: using a scanning laser to quantify the appearance of the optic nerve head. The Heidelberg Retinal Tomographer (HRT) [9] is one example.
- Scanning laser polarimetry: using polarised light to measure the thickness of the retinal nerve fiber layer. The GDx-VCC [10] is one example.
- Optical coherence tomography: using interferometry to obtain cross-sectional views of the retina and optic nerve head and to measure the thickness of the retinal nerve fiber layer. The Stratus OCT [11] is one example.
For the latter three the quantified results are then statistically compared to age-matched population norms, and to subsequent scans of the same patient over time.
References
- ↑ Haag-Streit Tonometers: Goldmann Tonometer
- ↑ Nidek Technology America, Inc., Greensboro NC, USA Nidek "3Dx Digital" Stereo Fundus Camera
- ↑ Herndon L, Weizer J, Stinnett S (2004) Central Corneal Thickness as a Risk Factor for Advanced Glaucoma Damage. Arch Ophthalmol 122(1):17-21
- ↑ Jonas J, Stroux A, Velten I, Juenemann A, Martus P, Budde W (2005) Central Corneal Thickness Correlated with Glaucoma Damage and Rate of Progression. Investigative Ophthalmology and Visual Science. 46:1269-1274
- ↑ Medeiros F, Sample P, Zangwill L, Bowd C, Aihara M, Weinreb R (2003) Corneal thickness as a risk factor for visual field loss in patients with preperimetric glaucomatous optic neuropathy. American Journal of Ophthalmology 136(5):805-813
- ↑ Doughty M, Zaman M (2000) Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol 44(5):367-408
- ↑ Shah S, Chatterjee A, Mathai M, Kelly S, Kwartz J, Henson D, McLeod D (1999) Relationship between corneal thickness and measured intraocular pressure in a general ophthalmology clinic. Ophthalmology 106(11):2154-60
- ↑ CBD Ophthalmic/Tomey, Arizona USA SP3000
- ↑ Heidelberg Engineering GmbH, Dossenheim, Germany Heidelberg Engineering: HRT3 Glaucoma
- ↑ Laser Diagnostic Technologies, Inc., San Diego, CA Carl Zeiss Meditec: GDx
- ↑ Humphrey Instruments, Dublin, CA Carl Zeiss Meditec: Stratus OCT