More frequently, patients are usually diagnosed as part of a routine eye test or as an incidental finding when presenting with another ophthalmic condition e. A detailed general history would reveal any causes of secondary glaucomas and therefore refuting POAG , such as steroid usage. Physical examination consists of assessment of IOP, anterior chamber angle, optic disc and visual field.
This is not available in all instances, and non-contact tonometry is also frequently used.
Almost standard now, in conjunction with tonometry, is the measurement of central corneal thickness CCT. Theoretically, a thinner cornea may lead to measurements that under-estimate true IOP and vice versa. However, the effect of CCT on IOP measurement is not predictable, and there is no consensus as to the degree of under- or over-estimation of IOP that occurs with thinner or thicker corneas. Moreover, CCT is only one biomechanical attribute of a cornea. For example, a thin cornea that is very stiff may still result in over-estimation of IOP.
Newer methods of IOP measurement aim to overcome variations in corneal biomechanics and give a more accurate estimate of true IOP. The ORA is a non-contact tonometer that measures a biomechanical attribute of the cornea termed hysteresis. The DCT uses uses principle of contour matching instead of applanation to reduce the effect of corneal biomechanics. For more information on tonometry, please see the section Intraocular Pressure and Tonometry. The anterior chamber angle is assessed clinically using the slit lamp Van Herick technique and with gonioscopy.
Clinical examination of the optic disc is a very important part of the assessment of patients with POAG. Direct ophthalmoscopy offers the most magnified view of the optic disc, but the view is not stereoscopic. Slit lamp biomicroscopy with a lens that offers large magnification e. Stereoscopic disc photographs offer a useful documentation of optic disc status, and also allow masked assessment in trials.
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Clinical assessment of an optic disc is still considered the gold standard in the diagnosis of POAG, though the inter-observer agreement is notoriously variable. Assessment of the nerve fiber layer surrounding the disc by the GDx is also useful. Automated static threshold perimetry e.
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Humphrey field analysis is the gold standard for diagnosis and monitoring of POAG. Various testing algorithms have been validated for POAG and allow reduced testing time for patients e. This rationale has led to development of new perimetric tests such as short-wavelength automated perimetry SWAP and frequency doubling technology FDT , which may be able to enhance earlier detection of functional loss by targeting a specific subset of ganglion cells that have sparse distribution.
This definition does not include IOP - i.
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Sometimes an IOP spike may be missed in a clinical setting. In these cases, if HTG is suspected, measurement of IOP at hourly intervals throughout the day, beginning in the early morning, may be indicated. This is termed phasing. By definition, the anterior chamber angle of POAG patients is open. Gonioscopy is essential to make the diagnosis of POAG and should be performed on the initial visit. Various classifications systems have been described to assess the extent of an open angle. Advanced POAG is a relatively clinical diagnosis. Patients will have undisputable characteristic optic nerve damage and restricted visual fields.
However, visual function loss from POAG is irreversible; therefore, it is critical to diagnose this disease as early as possible and prevent further loss of vision.
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Diagnosis of early POAG is more difficult. Optic disc changes or visual field abnormalities may be more equivocal. When the evidence for POAG is not compelling enough to commence therapy, the patient is referred to as a glaucoma suspect and reviewed regularly to watch for any signs of progression. An experienced clinician is able to assess clinical examination findings in conjunction with investigation results and make a decision as to the diagnosis.
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Clinical findings corresponding with investigative findings add weight to the diagnosis of POAG. For example, Figure 1 shows the left optic disc of a patient, and Figure 3 shows the left visual field of the same patient. The thinning of the superior neuro-retinal rim of the optic disc corresponds well with the dense inferior arcuate scotoma in the visual field. This provides strong evidence for glaucoma.
Another important characteristic of POAG is that it is a progressive disease. If optic disc appearances and visual field changes are static on no therapy, this would count against a diagnosis of glaucoma. Quantitative measures such as neuro-retinal rim area or volume and retinal nerve fiber layer thickness are useful for monitoring and assessing progression. Also, when compared with normal population values, they may give some indication of diagnosis e.
Features of visual field defects, detected on automated threshold perimetry, that are characteristic of POAG include:. Visual field testing is also useful for assessing progression. The video below shows progression of an inferior arcuate scotoma in a patient with glaucoma over a 4 year period. For more information, please see section Standard Automated Perimetry.
Vision loss from POAG is irreversible. Management is, therefore, aimed at slowing the progression of the disease, thereby maintaining optimum visual function. The study is comparing the rate of progression in early POAG between patients receiving latanoprost or placebo. IOP may be lowered by medical therapy topical and systemic , laser therapy and surgical procedures.
There is no strong evidence supporting which of medical, laser or surgical therapy should be given initially. For example, the CIGTS Collaborative Initial Glaucoma Treatment Study showed no significant difference in outcome between patients randomized to either medical therapy or trabeculectomy. Commonly, patients are started on medical therapy with possible adjunctive laser therapy, and only if these measures fail is surgery considered.
This provides some evidence that there are IOP-independent mechanisms at play. Therefore, searching for other reversible risk factors for POAG is essential. Medical therapy may be topical or systemic. However, it is important to appreciate that topical medication may cause significant systemic side effects, especially beta-blockers. The most efficacious class of drops is the prostaglandin analogues.
They are also the most convenient drops with once nightly dosage. Details if other :. Thanks for telling us about the problem. Return to Book Page. This book is your ultimate Glaucoma resource. Here you will find the most up-to-date information, facts, quotes and much more. In easy to read chapters, with extensive references and links to get you to know all there is to know about Glaucoma's whole picture right away.
Get countless Glaucoma facts right at your fingertips with this essential resource. The Glaucoma Handboo This book is your ultimate Glaucoma resource. The Glaucoma Handbook is the single and largest Glaucoma reference book. This compendium of information is the authoritative source for all your entertainment, reference, and learning needs. It will be your go-to source for any Glaucoma questions.
A mind-tickling encyclopedia on Glaucoma, a treat in its entirety and an oasis of learning about what you don't yet know The Glaucoma Handbook will answer all of your needs, and much more. Get A Copy. Medical visits also increase with the severity of the disease, from 2. Lafuma et al estimated in 9.
Economic evaluation studies are increasingly important because they facilitate decision making by health managers.
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Availability of new treatment and diagnostic modalities additionally imposes questions on how to better allocate resources, and these guidance studies are used for less management. There are several types of health technology studies: cost - minimization, cost - benefit, cost - effectiveness, cost - utility. Cost Minimization Analysis - Allows comparing costs, when two or more interventions are equal, in the clinical results. It only considers costs 18 usually only direct ones , when the results are the same. It is not possible to carry out this type of analysis when the results of interventions are not the same.
For example: The minimization analysis of a drug by different routes of administration. Cost-Benefit Analysis - Establishes the relationship between the costs associated with the treatment and the financial benefits generated by it. All costs investments and benefits consequences are measured in monetary terms. Examples: Relationship between the costs of a treatment and the saving of resources resulting from a shorter hospitalization time or costs of an early treatment program compared with a late treatment or its complications.
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The Cost-Benefit Analysis evaluates the cost of one product or service relative to others. In this type of Cost-Benefit Analysis , the intangible benefits such as health sense and value of human life are difficult to assess in monetary terms. Thus, cost - effectiveness analysis is more commonly accepted. The Cost - Effectiveness Analysis - This analysis studies the relationship between costs of a treatment and clinical benefits effectiveness for the patient.
This type of analysis allows the comparison of the costs of a treatment in monetary units as well as its results.