Perimetry’s role in glaucoma practice grows as testing becomes

ROUND TABLE PARTICIPANTS
Leo P. Semes, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board and is an associate professor of optometry, University of Alabama at Birmingham.	J. James Thimons, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board. He is also the executive director of TLC Connecticut and the medical director of Ophthalmic Consultants, a referral, secondary and tertiary level surgical practice.	Anthony B. Litwak, OD, FAAO, is the director of residency and student programs at the Baltimore/Fort Howard VAMC in Maryland.

Murray Fingeret, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board. He is also chief of the optometry section at the Department of Veterans’ Affairs Medical Center in Brooklyn and St. Albans, N.Y., and a clinical associate professor at SUNY College of Optometry.

Leonard J. Oshinskie, OD, FAAO, is the program director of the residency in primary care optometry and chief of the optometry section at the VA Connecticut Health Care System in Newington, Conn.

J. James Thimons, OD, FAAO: What is the standard of care for glaucoma diagnosis and management? Are any new technologies far enough into development that they have become standards in that area? Or, are we still dealing with the more traditional forms of glaucoma diagnosis? Let’s start with SWAP [short-wavelength automated perimetry], or blue-yellow perimetry.

Anthony B. Litwak, OD, FAAO: I think SWAP has a relatively narrow range of use. A lot of good studies show that blue-yellow perimetry does pick up damage earlier, so I would gear that test toward the patient who is a high-risk glaucoma suspect, meaning that he or she has multiple risk factors for the disease but tests normal on white-on-white perimetry. Other than with these types of patients, I don’t use it frequently.

PCON ROUND TABLE At the New England Council of Optometrists meeting in Providence, R.I., Primary Care Optometry News gathered five experts to discuss what they consider to be the standard of care for glaucoma diagnosis and management, advice on purchasing and upgrading perimeters and the place of perimetry in tomorrow’s optometric practice. Led by moderator J. James Thimons, OD, FAAO, other panelists included Anthony B. Litwak, OD, FAAO; Leonard J. Oshinskie, OD, FAAO; Leo P. Semes, OD, FAAO; and Murray Fingeret, OD, FAAO.

Leonard J. Oshinskie, OD, FAAO: We have just started to use SWAP a little bit. There are a few potential pitfalls to be aware of.

First, if you have a patient who is not a good test taker, SWAP is not going to be a good test for him or her in terms of feasibility or reliability. If he or she has difficulty on the white-on-white, SWAP is going to be very difficult. It is a longer test and it doesn’t help your efficiency in terms of glaucoma diagnosis. Additionally, if there are some lens opacifications, there are some questions regarding accuracy. Some studies say that you can still use it, but I would aim it at patients who are at high risk and who are younger.

Murray Fingeret, OD, FAAO: SWAP needs to be run in the FastPac setting. A FastPac at least gets you in the ballpark where some patients can do it.

Another issue is cataracts. The issue is not accuracy. People who have been part of the SWAP development will tell you that the biggest problems with the SWAP instrumentation, whether it’s with the Octopus or the Humphrey, have to do with the lighting source. Because it doesn’t get bright enough, many cataracts are going to render the test useless.

You lose the localized change, due to the elevator effect. Humphrey, in particular, will be making some major changes to SWAP. They’re going to be changing the lighting and doubling the dynamic range. The instruments are going to have a newer lighting source that will burn right through the cataracts to get a big, nice, dynamic range, along with going to a SITA [Swedish interactive threshold algorithm] mode.

Dr. Thimons: In our practice this test has been a nice additional component simply because it meets the needs of people for whom I’ll care for a long period of time. I don’t routinely use this on anybody older than 65 or 70, because I find that the information and the level of technology probably won’t be all that helpful. For younger patients with elevated pressures or early cup-to-disc changes that are suspicious, this is a great baseline test.

Dr. Fingeret: One thing that most practitioners don’t realize is that there’s a learning curve with SWAP that is different than white-on-white. You can have a skilled patient who has done a dozen regular fields. Now, if you run this patient on SWAP and you see loss, it doesn’t mean much because it’s a different test. You have to redo the test.

Dr. Oshinskie: Do you use the gray scale to interpret? I’ve heard that it’s not an appropriate test to use as far as SWAP.

Dr. Fingeret: One thing that has always been strange is that Humphrey never modified the gray scale. So, the gray scale with SWAP doesn’t have as much use as it does with the conventional perimetry.

Dr. Litwak: Another interesting thing is that the superior visual field is more sensitive to blue-yellow than the inferior visual field. So if you look at the gray scales, it’s going to look worse superior, and it’s corrected for when you look at the pattern deviation response.

Leo P. Semes, OD, FAAO: I don’t think this is something that’s going to become a standard. It’s going to be something that’s used when you’re trying to identify a high-risk patient. However, standard for us remains full threshold on an annual basis.

SITA: standard of perimetry?

Dr. Thimons: Please provide some comments about SITA (Humphrey Systems, Dublin, Calif.) and its current status. Has this become the standard of perimetry in optometry?

Dr. Semes: SITA is basically a different way to do the threshold test. It’s useful in patients who are reluctant to take the test or who are poor test takers.

Dr. Oshinskie: Are you talking about SITA Standard or SITA Fast?

Dr. Semes: We use SITA Fast.

Dr. Oshinskie: We have just started to use SITA, also. Until recently, at our hospital, the standard of care has been a 24-2 FastPac. We do 1,500 to 2,000 visual fields a year. We’ve been able to do FastPacs in about 5 to 6 minutes per eye, which allows us to do at least one additional field a day. So, in terms of efficiency, the FastPac 24-2 has been our preferred test. We have to be able to balance diagnostic abilities with the realities of life. Now, will the SITA Standard replace that? It might, but we haven’t used it enough yet to know.

Dr. Litwak: We have had SITA for a while. In fact, we had some of the early versions of SITA. It’s a new technology so you have to learn how to interpret the results. With the newer statistical software package, it’s accepting a narrower range of normal values. SITA is one test in which you probably don’t want to look at the gray tones but, you want to look at the pattern of deviation plots because you’re probably going to see a defect show up there more than you will in the gray tones.

As far as standard tests, if we had a new glaucoma patient, we’d probably run him or her on a 30-2 SITA Standard. If the patient is already an established glaucoma patient and can take a full threshold 30-2, we’ll keep him or her on that test because you can determine progression with it. If you switch to a SITA, you then have to establish a new baseline and then follow the patients with serial SITA visual fields.

The other patient who is going to benefit most from a SITA test is a full-threshold patient who is showing fatigue artifacts. Those patients should clearly go to an easier test. Whether it’s a FastPac or SITA Standard or SITA Fast depends on whether you have SITA capability.

The disadvantage of FastPac is that you can’t do glaucoma change probability or get a glaucoma hemifield test result.

Dr. Fingeret: I love SITA. I started with the test many years ago. However, there have not been that many data on SITA that prove or show that it’s comparable to full-threshold fields. Those data will be coming. The studies are showing that SITA is as accurate as, if not more accurate than, full threshold with even smaller or tighter limits for each point. So, you have greater reproducibility.

Even more interesting is that SITA Fast is as accurate as a full threshold. It is amazing how the data are coming out.

I can’t run patients back on full threshold anymore. I’d rather redo the baseline and run a 4-minute, 5-minute or 6-minute test than a 12-minute test. SITA is an innovative way to do a field, and I would be lost without it.

Dr. Oshinskie: Are you talking about SITA Standard?

Dr. Fingeret: I’ve used SITA Standard, and I reserve SITA Fast for patients who have limited attention spans. I don’t see any reason to go any other way.

Dr. Oshinskie: We used to do 30-2 full thresholds and found that the test just took too long. Patients couldn’t do the test accurately, especially in the second eye. They got so tired that we had to find a shorter test. So that’s why we went to FastPac. We got the SITA instrumentation in the past 6 months or so, so we’re making the change to SITA standard 24-2 which will probably replace FastPac 24-2 as our preferred test.

Dr. Thimons: In a managed care environment, where doctor time, technician time and equipment cost have to be dealt with on a daily basis, you need to find the best possible assessment mechanism that will maximize the efficiency of the overall process. This issue has arisen in our practice and has driven the move toward SITA in a much more direct way. Maximizing efficiency is really where SITA has its biggest role. It allows you to get excellent results without compromising integrity, but it diminishes time. That time effectively becomes available to the practitioner and to the office to use for other purposes. We’ve converted completely.

Dr. Litwak: Let’s remember the patient, too. These patients are actually smiling when they come out of the visual field room. If you can make the test quicker and just as accurate, then it’s a benefit to the patient as well.

Dr. Fingeret: The first time I took a SITA test, being a hyper New Yorker, I was impressed in that the test actually kept pace with me. As I was clicking away and getting faster and faster, the instrument got faster and faster as long as I was getting them right. Patients can sense that they can pace the instrument; they can run the instrument and it stays with that feel. It slows down or gets quicker as long as they’re within a certain window and as long as they’re reliable.

TOP: reduced testing time

Dr. Thimons: Let’s move on to TOP [tendency-oriented perimetry]. I’d like to get your comments on the TOP system produced by Octopus and its applications in optometry for glaucoma management.

Dr. Semes: I have no experience with TOP. We had a 1-2-3 in our practice, and I used to like the 1-2-3.

Dr. Fingeret: TOP is an interesting program in that it tests each point once and from there creates the visual field printout. It does this by interpolating and using readings from one point to influence many other points in a visual field.

There are not many data yet on TOP that show that it is as accurate as the full-threshold method, but it does reduce testing time significantly. That may be one important role. But it still needs to be worked out how TOP compares to other forms of perimetry. I hope that studies will be available in the near future.

FDT’s place in the future of diagnosis

Dr. Thimons: Do you have any comments about FDT [frequency doubling technology] from a general perspective? Obviously, it’s a technology that’s been available now for about 18 months and most of us, if not all of us, have had access to it and have had some experience with it. What have your experiences been?

Dr. Oshinskie: I have not used it.

Dr. Semes: If we were having this discussion a year ago, I would have said that it’s a cute little toy. I was not persuaded about its efficacy until a few articles came out from people who had done some work and established criteria. Now, I think, with some evolution in software and some evolving in the establishment of the criteria for diagnosis of glaucoma, as well as staging of the defects, it’s something for the future. It’s something that we’re going to be using to not only diagnose, but to manage glaucoma in the future.

Dr. Litwak: FDT is a very interesting and unique technology. The most useful role will be in glaucoma screening. Half of the glaucoma that’s out there is undiagnosed. We need quick accurate methods to screen patients who don’t know they have the disease. You can do this test in the screening mode in about 1 minute or 1 minute and 30 seconds. We really don’t have any other tests that can do it that quickly with good sensitivity and specificity.

The use of this instrument may not be in the optometrist’s or ophthalmologist’s office, but rather in a primary care physician’s office. All patients would have the test as a routine screening test for glaucoma. If it were abnormal, then the patient would get referred for a full eye examination.

So, I think FDT is going to be our glaucoma screening test in the future. However, I’m not so sure that it is going to be the way that we follow glaucoma progression.

Dr. Fingeret: The FDT is the first perimeter that truly has use both in the screening and the threshold arenas. Some glaucoma patients are difficult to pick up based on their optic nerve appearance, often because they have a small disc or an unusual disc size. Yet, we often rely on the nerve or the intraocular pressure (IOP) as our primary way to diagnose glaucoma, with the visual field being more confirmatory.

FDT just adds another tool in terms of screening, whether it’s in an optometrist’s office or mass screening.

Dr. Thimons: It’s an interesting instrument in the private sector because it allows for relatively rapid assessment. This instrument broadens the base of people who can actually have a quality visual field assessment system in their office because of its price and ease of use. Users, other than eye care specialists, will probably include clinics, internal medicine practices, general practices and pediatric practices.

Dr. Oshinskie: FDT, even though it’s a screening test for glaucoma, will also pick up other conditions that could affect the nerve fiber layer, such as branch retinal artery occlusions that may have resolved or other things like that.

Dr. Litwak: The FDT has been considered as a way to screen for diabetic retinopathy. It is my clinical impression that the retinopathy must be very advanced before you start to see visual field defect on FDT.

Dr. Fingeret: That probably has to do more with the spatial resolution. Right now there is only one 5° target within the posterior pole.

Follow-up visual field testing

Dr. Thimons: When do you need to do the first visual field after you’ve made a diagnosis of glaucoma? You’ve seen the patient, the consult is completed, the visual field was done as part of the initial work-up and now you’re going to have the patient back for chronic care. What constitutes a normal pattern in visual field testing?

Dr. Oshinskie: I think that depends on how advanced the glaucoma is and the patient’s risk factors. Obviously, a patient with a 0.9 cup who has a family history of glaucoma and is African American needs to come back in about 6 months for a visual field.

Dr. Thimons: Typically, in a patient on whom you’ve started therapy and with whom you’re comfortable, how often are you going to do visual fields?

Dr. Oshinskie: Once a year.

Dr. Litwak: It depends on the individual case and whether the patient has met his or her target pressure.

Dr. Thimons: Let’s say he or she has done all of those things.

Dr. Litwak: Initially, you might want to repeat the visual field in 6 months. If that’s stable, then you can go a year.

Dr. Semes: Once a year is pretty standard, but it is very individualized. Fields are great because they are quantitative and you can take a look at the progression. You can even pin a number down, much like we used to do with IOP, but I think we’re going to see in the future an assessment based on optic nerve appearance.

Dr. Fingeret: I think Dr. Litwak hit it right on the head. I like to get a field at 6 months out after they’ve been diagnosed, almost to re-complete the baseline where there still may be some learning effect. Then, if it appears to be unchanged, I do it once a year. But it also depends upon the level of glaucoma disease. For more advanced glaucoma, I’ll do it more often.

Dr. Oshinskie: If the patient has severe glaucoma, say 0.8 to 0.9 cup or so, it is important to do a 10-2 in addition to 24-2 so you can monitor the field close to fixation.

Dr. Thimons: What criteria do you use to establish the repeatability levels of visual fields? You’ve mentioned optic nerve cupping. Are there characteristics that cause you to accelerate that from once a year to more than a once-a-year process?

Dr. Fingeret: If you ever see any change, you need to repeat that field. You have to confirm change because the Ocular Hypertension Treatment Study work that was published showed how common it is for fields to flip-flop. You see loss that turns out not to be real. It is just, in essence, variability.

When more frequent testing is needed

Dr. Thimons: Are there any other characteristics on the part of the patient that would cause you to go toward a more intensive field schedule? Is diabetes an issue once a patient has been diagnosed with glaucoma? Is that a concern that makes you run fields more frequently?

Dr. Litwak: I don’t think diabetes really is an issue. Some studies show that family history of glaucoma, especially if a sibling has it, increases your risk significantly, like 17 times. So, that might be one of the things that would make you want to follow that patient more closely. If the patient is not compliant with medications, you may want to do the fields more frequently.

Dr. Thimons: Would IOP fluctuation influence your decision? If the IOP is eroding and the control is eroding, are you going to repeat the field?

Dr. Litwak: If a patient is not at the target pressure, that’s certainly a reason to do it more frequently.

New purchase recommendations

Dr. Thimons: What would you recommend to a practitioner today who was purchasing a new perimeter?

Dr. Litwak: If I were going to buy a new perimeter right now, it would be an Humphrey Field Analyzer (HFA) II. I think that the capabilities of SITA and SITA Fast are going to become the standard of care.

If I was in a practice where I was not necessarily managing glaucoma but just wanted a field unit that could do screenings and diagnose the disease, I might consider an FDT because it’s less expensive and very easy to use. You can use it as a screening tool in your office or clinic, because it’s very quick and doesn’t require any special user training. Additionally, patients adapt to the test fairly quickly. However, if I were going to be managing glaucoma patients, I’d go with the HFA II. SITA is not available on the HFA I.

Dr. Oshinskie: I agree. I think that it certainly sounds like SITA is being used more and more and is going to become standard. The availability for SWAP testing is going to be important, so a field analyzer that offers it will be valuable.

Dr. Semes: This is a very difficult question to answer. If I were making a recommendation for someone, I’d say to look at the literature, and make your decision based on that.

Dr. Thimons: A lot of practices are looking to get an entry-level system. They want something that will provide screening and a threshold-based assessment.

FDT has appeal, because the price is well positioned relative to what you can gain.

If you’re going to manage glaucoma, you need equipment that maximizes patient assessment. Additionally, it’s going to be the highest level of technology available. The HFA II meets these criteria.

Dr. Fingeret: One of the things that makes the FDT unusual is the number of peer-reviewed articles that have come out on it. It’s the same thing with SWAP. There is a lot of science behind these; it’s not smoke and mirrors.

Dr. Thimons: Do you consider any of these new technologies essential? Is there anything you have today that you would be unwilling to go without over the next 5 years?

Dr. Semes: If I had to give something up it would be the blue-yellow.

Dr. Oshinskie: But I think it’s going to become an important part of testing as time goes on. I think we want to keep it around, together with SITA.

Dr. Litwak: We need a test that can give you full-threshold values. I don’t think that everyone has to jump into SITA right away if they have a full-threshold perimetry unit. SITA certainly has the potential to become the standard, but as long as you’re following glaucoma patients with visual fields that can do thresholding perimetry, that’s the standard right now.

Dr. Fingeret: Early diagnosis is the key. While full threshold establishes the baseline, there may be some ways to tap into or recognize the disease process earlier. That was originally where SWAP came out. SWAP has been an underperforming test because of its limitation. In the future, I think it will turn out to have more significance.

In the future, it may be that we don’t have one test, but a series of tests to manage glaucoma.

Dr. Litwak: The FDT and the full threshold are different tests, so you’re going to pick up glaucoma in some patients on the FDT that you won’t pick up on full threshold and vice versa.

Dr. Fingeret: It’s really a combination of several things that will catch more people.

Dr. Oshinskie: I think it’s important to have an instrument where you can test people in wheelchairs easily. We’ve found that very helpful in our setting.

Perimetry in the future

Dr. Thimons: How do you see perimetry being used in tomorrow’s practice of optometry?

Dr. Fingeret: Perimetry has a large role in our practice. I don’t see it going away. As these tests get quicker and more efficient, it is just as important.

I have just found that there is a huge overlap between normal and abnormal in the optic nerve. Fields still are very important for me, and I still rely on them a lot of the time. Perimetry in my practice is still huge, and it always will be.

Dr. Semes: I’m coming from the academic side. What we may see in the future is perimetry in some form, some screening script, that you apply to every patient.

Dr. Oshinskie: I see perimetry becoming more efficient by various testing strategies that take out some of the subjectiveness.

Dr. Litwak: Visual fields are here to stay for a while at least. Our goals are to make the test quicker, and I think that SITA will accomplish that. You want to make it more accurate. Hopefully, SITA will do that by decreasing the amount of patient fatigue.

Determining progression of disease is still something that is very difficult to do with perimetry. There’s long-term fluctuation in glaucoma patients, and points can change quite a bit that could be progression of the disease or could just be long-term fluctuation. That’s why, in many studies, patients have four or five visual fields to determine if they’re progressing or not. Something to address that issue is really the main thing that we need to look at in the future.

For Your Information:

• J. James Thimons, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board and can be reached at Ophthalmic Consultants of Connecticut, 165 Stella Lane, Fairfield, CT 06432; (203) 255-6196; fax: (203) 254-1467. Dr. Thimons has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Anthony B. Litwak, OD, FAAO, can be reached at VA Medical Center, 10 N. Greene St., Baltimore, MD 21201; (410) 605-7230; fax: (410) 605-7232; e-mail: litwak.anthony@baltimore.va.gov. Dr. Litwak has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Leonard J. Oshinskie, OD, FAAO, can be reached at VA Connecticut Health Care System, 555 Willard Ave., Newington, CT 06111; (860) 667-6742; fax: (860) 667-6833. Dr. Oshinskie has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Murray Fingeret, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board and can be contacted at St. Albans VA Hospital, Linden Blvd. and 179th St., St. Albans, NY 11425; (718) 526-1000; fax: (516) 569-3566; e-mail: murray@liii.com. Dr. Fingeret has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Leo P. Semes, OD, FAAO, is a member of the Primary Care Optometry News Editorial Board and can be contacted at 1716 University Blvd., Birmingham, AL 35294-0010; (205) 934-6773; fax: (205) 934-6758; e-mail: LSemes@icare.opt.uab.edu. Dr. Semes has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
• Humphrey Systems can be reached at 5160 Hacienda Dr., Dublin, CA 94568; (877) HUMPHREY; fax: (925) 557-4778; Web site: www.humphrey.com.
• Octopus Perimeters, a Division of Haag-Streit AG, may be reached at 5500 Courseview Dr., Mason, OH 45040; (800) 627-6286; fax: (513) 336-7828.