Glaucoma Technology

By Jason Wanner, DO

Maryland Eye Associates

. http://marylandeyeassociates.com

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Glaucoma Technology

Technology plays a major role in all aspects of glaucoma. Technology can help in the initial diagnosis of glaucoma. As glaucoma technology has improved so has our ability to diagnose glaucoma earlier in the course of the disease. It can help us assess disease progression. Technology has allowed us to follow glaucoma closer for subtle advancement or worsening of the disease over time.

Glaucoma technology is important for helping to diagnose glaucoma as well as for following the progression of the disease. We use ultrasound to measure the thickness of the cornea, the clear front part of the eye. Thin corneas are an independent risk factor for glaucoma. Thin corneas also tell us that the eye pressure readings that we obtain are falsely low.

Visual field testing is another area in glaucoma technology that has come a long way. Visual fields help evaluate functional damage. We now have automated perimeters with many different computer programs we can use with the patients. The automated perimeters help to make the visual field tests more reliable and easier to compare for changes when evaluating the progression of the disease. With the advanced automated visual fields, we are able to calculate such things as fixation losses, as well as false positive and false negative responses. These indices tell us how reliable the individual tests are. We now have computer software that can look at data points comparing visual field results over time.

Nerve fiber analysis and optic nerve analysis technology looks at structural damage that occurs in glaucoma. The Retinal ganglion cell axons carry vision from the eye to the brain. These axons travel from the ganglion cell layer to the retinal nerve fiber layer to the optic nerve and then eventually to the lateral geniculate nucleus in the brain. There are many machines available to aide in evaluating the retinal nerve fiber layer and the optic nerves. The most commonly used machines are the GDx, HRT, and OCT.

The GDx, Glaucoma diagnostic, is a scanning laser polarimeter that measures the retardation of the retinal nerve fiber layer. The amount of change (retardation) in the light is proportional to the retinal nerve fiber layer thickness. With this technology changes over time can be observed.

The HRT, Heidelberg retina tomograph, is a confocal scanning laser ophthalmoscope. It creates a topographical map of the optic nerve head and surrounding retina. Software allows comparisons to be made with this over time.

The OCT, Optical Coherence Tomographer, measures the peripapillary retinal nerve fiber layer and the optic nerve head. The retinal nerve fiber layer analysis is a compilation of multiple circular scans of the retinal tissue just before reaching the optic nerve. The optic nerve analysis is a compilation of multiple linear scans centered directly on the optic nerve. The computer software allows us to follow the analysis for changes over time.

Technology has and continues to be a very important part of our ability to diagnose and treat glaucoma. It allows us to diagnose the disease earlier in its course. It has also allowed us to diagnose progression in the disease. Both of these contribute to our ability to treat glaucoma and improve the long-term prognosis for the patient.