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Glaucoma Dialogue IGR 12-4

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Comment by George Spaeth on:

46501 Treating patients presenting with advanced glaucoma - Should we reconsider current practice?, King AJ; Stead RE; Rotchford AP, British Journal of Ophthalmology, 2011; 95: 1185-1192

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Caring for patients who, w hen first examined, have far-advanced glaucoma is a challenge. The article by King et al. deals with the possibility of initiating treatment with surgery. After an extensive review of the literature using a methodology similar to 'meta-analysis', they conclude that there is not enough evidence to support this approach, and they advise continuing the current practice of starting with medications and then progressing to surgery if that appears appropriate. There are, however, major practical and conceptual concerns with this conclusion.

The most serious concern relates to the belief that it is possible to come up with a 'best approach'. People in all fields of medical care continue to look for 'the philosopher's stone', that elusive element sought by alchemists in times past that would turn ordinary materials into gold. We have a desire to simplify, which may becoming a more poignant need in times when there is so much complexity in the world and so many options. Nevertheless, the approach is often as unwise today as it was 500 years ago.

One of the major flaws of the review article by King and colleagues is the basic approach, which is to consider the patient's condition at one point in time. They are addressing the issue of patients with advanced glaucoma. Such individuals are at increased risk for becoming disabled by their disease, because any worsening at all increases their symptoms. This is in marked contrast to patients with early glaucoma or ocular hypertension, in which definite worsening of their condition can occur, yet without any change in their ability to perform the activities of daily living. The default position, then, for patients with advanced glaucoma must be: 'Treatment needs to be designed to prevent any further visual field loss.' But yet, as the authors point out, there are significant risks to treatment, especially to surgical treatment in patients with advanced glaucoma, in whom the complications of 'wipe-out' or the development of cataract are especially troublesome. Consequently, moving ahead with surgery as the first treatment in such patients may not be optimal, as properly pointed out in the review.

But there is an additional reason not discussed, which is as important or more important. Specifically, glaucoma is a condition which, when untreated, always gets worse. However, the rate at which it gets worse varies dramatically from patient to patient, and from time to time in the same patient. Not all patients with advanced glaucoma will progress within the period of time that is still allotted to them to live.

Not all patients with advanced glaucoma will progress within the period of time that is still allotted to them to live

This may be because the rate of change of their disease is slow, or the remaining years are few, or a combination of these two factors. Not taking into account the rate of change of the condition, and the estimated years remaining is an inappropriate approach to patient care.

Not taking into account the rate of change of the condition, and the estimated years remaining is an inappropriate approach to patient care

Both of these factors must be known if care is to be optimal. The rate of change in patients who are seen for the first time with advanced glaucoma can, in fact, be quite well understood. This is because such patients are symptomatic. Because they are symptomatic, when their condition progresses their symptoms become worse. Individuals, then, who say that they are quite sure that they have found no difference in their ability to perform the activities of daily living for the last ten years are describing a particular type of glaucoma which is very different from that which occurs in individuals who says that five years ago they were driving well, three years ago they became concerned about their ability to see well enough to drive, and six months ago they concluded it was totally unsafe for them to drive anymore and they stopped. Now add to that history information that suggests that the estimated years remaining for the first, stable patient may be one or at the most two years, and for the second, worsening patient ten or twenty years. Clearly the approach to the care of the first patient needs to be vastly different from that for the second!

Many physicians appear to be reluctant to embark upon the task of 'estimating years to live'. Nevertheless, they do this consistently every time they say a patient's age when they are presenting information about a patient. For example, patients with ocular hypertension who are 25 years old are frequently advised to initiate therapy, where those who are 85 years old are usually advised not to start treatment. The basis of this is physicians' belief that they can estimate the number of years remaining on the basis of the patient's age. However, this is not correct. Age is not a good indicator of the number of years remaining. However, it is not a difficult task to come up with a fairly accurate estimate of number of years remaining, as has been shown in several articles including that by Lee.¹ A second misunderstanding is the widespread belief that patients with advanced glaucoma are more likely to worsen than patients with less advanced glaucoma. On a population basis, this seems to be unquestionably true. A population of patients with advanced glaucoma is comprised solely of patients with advanced glaucoma, whereas a population of patients with less advanced glaucoma is comprised of some patients who have a very mild form of glaucoma that will worsen at a very slow rate, and some patients who have a severe form of glaucoma which will worsen rapidly. However, it may be difficult or impossible to distinguish between those two subsets at the time the patients are in the stage of their early or moderate glaucoma. Thus, it is certain that the amount of deterioration in the population of advanced glaucoma patients will be greater than the amount of deterioration in the population of patients with less advanced disease. However, the cause for the difference in the percentage of patients getting worse may have nothing to do with thestage of the disease, but only with the severity of the disease. The same basic reasoning applies to a population of patients with far-advanced stage of disease, which probably consists of individuals with varying degrees of severity. Some may have reached a stage of advanced disease because their glaucoma has been relatively mild but present for fifty years, whereas others may be at the same stage of advanced glaucoma because they have a particularly severe type of glaucoma which has progressed rapidly over a period of one year. Making an effort to estimate the severity of the patient's glaucoma, then, is essential for developing a plan of rational care. In conclusion, there are times when it is appropriate to initiate treatment with surgery and times when it is not. The authors provide little help in making this decision.

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