The Optic Nerve And Target Intraocular Pressure

In the absence of structural of functional findings on examination of the optic nerve, the clinician certainly must refrain from rapidly advancing therapy to an intolerable or unacceptable level. Nevertheless, advancing optic disk or retinal nerve fiber layer damage even without observable visual field loss is progression and under certain circumstances can be an indication for surgery. Efforts should be directed at estimating the rate or risk of progression. Glaucoma patients who are at highest risk for progression should be identified and the threshold for surgery lowered. Conversely, those glaucoma patients who are at lowest risk should be followed with structural and functional testing of the optic nerve to identify early progression.2 The risk of progression needs to be weighed against the risks and benefits of surgery and the life expectancy of the patient.

Regardless of whether there is an apparently adequate IOP with medical treatment, surgery is indicated if there is progressive worsening of the visual field, progressive optic disk damage, or thinning of the retinal nerve fiber layer. IOP that consistently exceeds the target suggests the possibility of progression even if the visual field, the optic disk appearance, and retinal nerve fiber layer are unchanged. The extent and location of damage may alter the threshold for surgery. Patients with advanced damage or damage threatening central vision should have lower IOP than those with early disease. One also should keep in mind that elderly patients with slow progression may have no change in quality of life during their lifetime and often can be observed on medical treatment. In addition, patients who have become blind from glaucoma in one eye despite good medical management and those with a strong family history of blindness from glaucoma are candidates for earlier surgical intervention. With so many classes of medication available, it is essential that the ophthalmologist set an appropriate IOP target and not wait for progressive visual field or optic disk changes before escalating therapy.

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