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Early Glaucoma - Round Table

R.A. Hitchings, A. Heijl and C. Migdal

Introduction

In May 2003 a group of European Union Glaucomatologists were gathered together in St. Tropez to discuss the issue of 'Early Glaucoma'. This discussion was divided into three parts, 'definition, detection, and management'. The outcome of these discussions has been summarised below. The 'St. Tropez Standards' set out the current state of knowledge within Europe. These have been summarised as ten key points for each of the three sessions. While these key points cannot be taken as all inclusive or proscriptive, they do provide a guidance source for the general ophthalmologist that can guide him in his practice today.

The St Tropez standards are to be read in conjunction with the EGS guidelines. Although these standards were not developed under the auspices of the EGS, they reflect ideas held by European Glaucomatologists. It has to be remembered that with further advances in our understanding of primary open angle glaucoma, these standards are likely to evolve over time. However they are current, pertinent and practical and therefore could be taken as guide points for the present. They constitute a matching of the ideal with the art of the possible.

Ten Salient points for Detection and Screening of Early Glaucoma
(Chair A. Heijl)

• Secondary prevention is detection of undiagnosed disease.
• For screening to be motivated, the disease should be sufficiently common, effective treatment and good diagnostic methods should be available.
• Management should aim at preventing disability and blindness, nothing else matters for the patient.
• Screening programmes must consider cost and health care priorities.
• Is it responsible for the profession to focus only on patients already under care instead of the population at large? Fifty percent of all patients with manifest glaucoma are undiagnosed.
• If screening, we probably must target high specificity and accept detection of only well established glaucoma.
• Detection of very early disease in screening situations with a low disease prevalence is likely to result in non-acceptable number of false positives.
• If screening, what population should we screen, e.g. what ages?
• What instruments and interpretation criteria (cut-off levels) are likely to be most appropriate?
• Can screening cause more harm than benefit? QoL, false positives? 

Ten Salient points for Diagnosis of Early Glaucoma
(Chair R. Hitchings)

• More health care does not necessarily improve health, but may increase harm.
• Glaucoma diagnosis is satisfactory if there is visual loss, good if it is linked with changes in the retinal nerve fibre layer or optic disc and very good if these changes are reproducible in images.
• It is likely that there is a continuum of changes from subtle changes in the retinal nerve fibre layer to changes of the optic nerve head to pre-perimetric loss of visual function, to reproducible loss with white on white perimetry.
• Early glaucoma may be diagnosed as someone with unequivocal signs but need not have either an intra ocular pressure above the upper limit of normal, or a defect on white on white perimetry.
• The relationship between structural and functional loss has been clarified from primate experiments. These relate retinal ganglion cell loss with perceived reduction in visual function.
• There are ethnic variations in visibility in the retinal nerve fibre, parameters of optic disc morphometry and in the normal range of intra ocular pressure.
• Telling the patient that he or she has glaucoma often leads to a negative psychological effect.
• SWAP sensitivity is higher than standard achromatic perimetry. SWAP is clinically available and can be used for making early diagnosis.
• Glaucoma may be diagnosed without evidence for progression. Detecting progressive disease makes the diagnosis more certain.
• Natural history studies have indicated time to progression and given some clues as to rate of progression in untreated glaucoma. Ten percent of patients can have detectable change on white on white perimetry within one year, but 30% will have no detectable change by the same assessment method within five years.

Ten Salient points for Treatment of Early Glaucoma
(Chair C. Migdal)

• Early glaucomas do tend to progress to advanced glaucomas with time. The question is at what stage and how intervention should occur. There is no treatment formula that encompasses all eyes.
• The careful monitoring of both disc and visual field for change is important in order to assess the rate of change.
• Setting an individual target pressure for each eye is essential.
• Results of the Randomized Controlled Trials may provide some guidelines and evidence for management, but do need to be translated into how they might be applicable to the individual i.e. not one simple rule for all.
• Results of the Early Manifest Glaucoma Trial (EMGT) do not suggest treatment for all. Average progression was slow, although there were some rapid progressors. The latter are the ones that need to be targeted.
• In visual field monitoring, there is a move from global to focal detection of defects.
• Disc analysis may be more useful in early glaucoma, and field change later in the disease.
• With earlier detection, there will be an increase in the number of glaucomas detected that require treatment. This is important regarding costs. Costs of therapy per year increase dramatically per increasing stage of the disease.
• Data from the Ocular Hypertension Treatment Study (OHTS) emphasized that not all OHT patients need to be treated. It is important to target those for treatment who have a greater than 3-4% risk per year. It is now evident that certain factors carry a higher risk of progression. Assess the risk factors in each patient and treat those at higher risk more aggressively.
• It is essential to balance the risks and outcomes of glaucoma with the healthcare needs of the population. Costs of drugs are increasing, cost of hospitalization is increasing, patients are more demanding and are living longer. Targeting individual needs is thus imperative.
  

This Round Table was made possible by an unrestricted educational grant from Allergan.