OGS PRESIDENT'S MESSAGE

Welcome to the first edition of the Optometric Glaucoma Society’s electronic journal. The journal's goal is to help all eye practitioners and scientists, worldwide, stay up to date in regards to emerging ideas and developments related to glaucoma. Paul Spry, MCOptom, PhD (Bristol, UK) will be our editor in chief, with Brad Fortune, OD, PhD (Portland, OR), Shaban Demirel, BSc (Optom), PhD (Portland, OR) and Algis Vingrys, PhD (Melbourne, Australia) serving as associate editors. As you can see, our editorial staff has an international flavor that we hope will allow us to tap into the different ways glaucoma is practiced around the world.

The Optometric Glaucoma Society (OGS) was founded in 2002 with a mission to promote excellence in the care of patients with glaucoma through professional education and scientific investigation. More information on the OGS may be found on our website, www.optometricglaucomasociety.org. The OGS is part of the Association of International Glaucoma Societies (AIGS). The AIGS is an umbrella organization made up of the 16 regional glaucoma organizations from around the world. Information on the AIGS is found at www.globalaigs.org.

The OGS e-journal will be published on a quarterly basis and sent automatically to everyone who registers to receive it. While this inaugural issue has been sent to a wide audience, future editions will only go to those who specifically ask to be included. Enrollment is simple and quick. Simply click on the subscribe text on the left or at the end of the E-Journal and follow the instructions.

This journal is published with an unrestricted educational grant from Pfizer, Inc. We would like to thank Pfizer, and especially Suzy Obst and Richard Black, for their generous support.

We welcome your feedback and comments. Please let us know how we are doing.

Murray Fingeret, OD
President, Optometric Glaucoma Society
murrayf@optonline.net

EDITOR'S WELCOME

The purpose of this journal is to bring up-to-date, useful and clinically relevant information direct to those interested in the glaucomas. We want to help clinicians stay informed about all aspects of glaucoma care: from detection, through treatment to monitoring with the ultimate aim of helping you to maintain high quality practice. The journal will promote best clinical practice and, we hope, will contribute to the evolution of future standards for glaucoma care.

As you will see, the journal is divided up into digestible sections, each covering a key aspect of glaucoma practice. Many of these are practical and will review clinical cornerstones using examples, such as the quarterly disc, visual field, image and case reviews. Other sections will describe and discuss the evidence base that underpins glaucoma care (Clinical Trial Review) identify emerging concepts and promising techniques that may change the way we practice (New Ideas & New Papers) and provide the very latest glaucoma news from meetings. As the Optometric Glaucoma Society President has described, we have cultivated a global flavour and created an "International" column to provide an opportunity and forum for us all to learn from each other and think outside our own regional comfort zone. Also, if you have a glaucoma-related query that you'd like to canvas our opinion on, then please ask us using the 'Clinical Question and Answer' section.

I very much hope you find the journal content to be informative, convenient, user-friendly and that you will subscribe to complimentary future issues. I would welcome any feedback that may help us provide you with the best resource available.

Paul GD Spry, PhD MCOptom
paul.spry@ubht.swest.nhs.uk

2005 OGS HONOREE. PROFESSOR STEPHEN M DRANCE The 2005 meeting of the Optometric Glaucoma Society will recognize and honor the many scientific and professional contributions of Stephen M. Drance, OC, MD. Professor Drance's more than 300 contributions to the glaucoma literature span half a century and address every conceivable aspect of the disease. For 18 years, he served as Chairman of the University of British Columbia's Department of Ophthalmology, a department in which clinical care merged seamlessly into an environment of teaching and research. Professor Drance has trained 35 fellows, whose contributions continue to move glaucoma care forward. His accomplishments have been widely recognized, through numerous honorary fellowships, honorary degrees and awards. In 1987, Professor Drance was appointed as an Officer of the Order of Canada, one of the highest honors his country bestows. His passion for music and the visual arts led him to found the Vancouver Summer Festival, and this year he received the Vancouver Arts Award in recognition of his philanthropy in the arts. We are pleased to announce Professor Stephen M. Drance as the 2005 OGS honoree.

NEW IDEAS & NEW PAPERS

One challenge facing clinicians is the question of whether to treat a patient suspected of having early glaucoma. Our common sense, clinical training, and now too, data from several prospective, longitudinal clinical trials, guides us to consider the relative risk associated with each individual patient (or eye). We consider age, race, IOP, corneal thickness and clinical status among other factors prior to recommending treatment (or follow-up). When the patient has reproducible, even if only "early" visual field abnormalities, this decision becomes less ambiguous. However, when the visual field is normal, the decision depends more on the apparent structural integrity of the optic disk. We know this can create uneasiness because of the degree of overlap between normal and glaucomatous eyes in terms of disk appearance.

One recent paper by Medeiros and colleagues did an excellent job discussing this issue as they presented results of their study on the diagnostic utility of scanning laser polarimetry (SLP). In their study, the diagnosis of glaucoma was defined as progressive change in the clinical appearance of the optic disk, that is, glaucomatous optic neuropathy (GON). Using the GDx VCC to obtain SLP measurements, they found that the "nerve fiber indicator" (NFI) parameter had a diagnostic sensitivity of 83%, with a specificity greater than or equal to 80%, in eyes with "preperimetric" GON, (i.e., eyes with normal threshold visual fields). They elegantly discussed how the NFI parameter might best be used to assess risk by calculation of likelihood ratios. For example, eyes with an NFI score between 35 and 50 were nine times more likely in patients with preperimetric GON than in controls. To quote, "this indicates that an NFI value greater than 35 would substantially raise the suspicion of disease" in an eye with a normal visual fields but a suspicious optic disk appearance. Thus, aside from suggesting that SLP offers a potentially helpful aid in the diagnosis of glaucoma suspects (and for treatment recommendations), this paper also did an excellent job arguing that progressive change should define GON. Hence, we should all endeavor to carefully document the appearance of the optic disk at baseline, and regularly during follow-up of our patients. Probably the best current technique for doing this is simultaneous-stereo photography.

Brad Fortune, OD, PhD

1. Medeiros FA, Zangwill LM, Bowd C, Sample PA, Weinreb RN. Use of progressive glaucomatous optic disk change as the reference standard for evaluation of diagnostic tests in glaucoma. Am J Ophthalmol. 2005;139:1010-1018.

VISUAL FIELD REVIEW

This is an example of an unreliable visual field with a high number of false positive and false negative responses as well as fixation losses. The first clue that something is amiss is that the gray scale has white sections which correlate to very high sensitivities. This is confirmed in the raw data section in which the actual responses are in the 40-50 dB range. The normal individual sensitivity peaks around 36-38 dB. These results are due to a patient clicking the response button when they are not actually observing the stimulus. Other indicators of an unreliable field due to a "happy clicker" is that the false positive response is at 26%, which is quite high (above 15% is unreliable), more points are flagged on the pattern than total deviation side of the printout and the Glaucoma Hemifield Test (GHT) reads abnormally high sensitivity. Usually, unreliable fields associated with high false positives appear better than they are in reality, and this particular field provides no help in regards to understanding if a field defect is present. The patient should be educated that they are not expected to see all targets and possibly, with practice, a useable field may result

On this 'white scotoma' visual field, the impossibly high threshold values result from false positive responses and may mask true defects present. The question is, why do patients do this? Perhaps this is because they sometimes feel they must respond while the light is still on, although this is virtually impossible actually given the 200 msec presentation. They need to be told there will be a brief flash of light, and then the machine will wait 2-3 seconds for them to respond, so they have time to make a deliberate response and should be sure they saw a light. With SITA fields, the machine initially measures the patient's response time, averages the last 10 correct responses, and waits twice this average for subsequent responses. In that way it goes slow enough for those who are slow, but doesn't bore people who makes quicker decisions. You can see how once a person responds quickly, the test goes faster and faster, perhaps making the situation worse, so they should go at a comfortable pace and know the machine will wait according to their pace.

IMAGE REVIEW

This 53-year-old presented for a comprehensive examination. He failed a screening visual field test, done as part of the pre-test battery. During the examination, his intraocular pressure was found to be elevated (Ta 25/28 mm Hg) and the corneas were thin (528 um/ 529 um). The optic discs were average in size and in particular the left optic nerve did not obey the ISNT rule. The rim was thin superiorly. Zone beta was present in each eye, but more obvious in the left eye.

The HRT image (top, left), which is reliable with an SD less than 20 um in either eye, reveals the cup to be larger in the OS with thinner rim tissue and failed sectors on Moorfields Analysis, especially superiorly in the OS. The GDx printout (top, right, also a quality printout as seen by a Q of 10 or 9) shows greater loss also in the OS, with the retinal nerve fiber layer thickness map revealing significant loss as seen by the blue appearance. Parameters are flagged on the left side (seen by the red color) and the deviation map shows significant loss in the OS while the TSNIT graphs show loss superiorly in each eye, but greater in the OS. The OCT printout (above, right) shows loss primarily in the OS with the rim tissue thin superiorly. The superior region in the OS falls into the red zone on the TSNIT curve, and the superior sectors and quadrants are flagged for the OS only. These images confirm the optic nerve appearance of glaucomatous damage present in the left eye.

While there is emphasis on the upper sector of the disc in the left eye, note that the nerve fiber layer is thinner nearly everywhere than in the other eye, even if still in the statistical normal range. This is not only helpful diagnostically, but helps us realize that there is often an early generalized loss of axons from mid to lower normal range before or at the same time that one sector becomes abnormal, so localized loss helps us recognize abnormality, but general loss has also occurred. It also points out that comparing the two eyes is useful. This is most easily noted on the OCT and GDx printouts.

QUARTERLY CASE

A 78-year-old white asymptomatic male patient presented for examination. Questioning revealed that he was fit and well, had no cardiovascular disease, diabetes or history of hemodynamic crisis. He was not taking any systemic medication and did not experience migraine or cold extremities. No family history of glaucoma or blindness was reported.
Visual acuities were OD 20/17 OS 20/30. Anterior segment examination was unremarkable. Goldmann applanation IOPs were OD 25 and OS 28mmHg. Central corneal thickness (CCT) was close to the population mean at 544 microns bilaterally and so did not impact IOP measurement accuracy.

Optic nerve heads (ONHs) were assessed by slit lamp examination and fundus lens. Disc heights were equal at 1.8mm OU: close to average in size. Cup-to-disc ratios (CDR) were R 0.75 and L 0.80. The neuroretinal rim (NRR) of the right ONH was thinnest superiorly. The left disc excavation was deeper than the right with visible lamina. NRR thinning was generalized, and the entire temporal NRR was thin. Neither disc obeyed the ISNT rule. These features combined to give an overall clinical impression that ONH appearance is consistent with glaucomatous optic neuropathy, worse in the left eye.

Standard automated perimetry was performed with the Humphrey Field Analyzer program 24-2. Test results were reliable bilaterally. The right eye had normal global indices and a Glaucoma Hemifield Test (GHT) ‘within normal limits’ although a suspicious cluster of test locations was present in the inferior arcuate region (see pattern deviation probability plot). The left eye had test locations with sensitivities outside the normal range in arcuate regions, greater inferior than superiorly, with Pattern Standard Deviation, Mean Deviation and GHT confirming this abnormality. Due to the concern for glaucoma developing, gonioscopy was performed. The angles were bilateral wide open (Shaffer grade IV, all quadrants) and were physiological in appearance.

Although this patient had no demographic or systemic risk factors for primary open angle glaucoma development, he exhibited all the diagnostic requirements for primary open angle glaucoma (POAG) as follows; (1) gonioscopically open anterior chamber angles; (2) elevated IOPs; (3) glaucomatous optic nerve head appearances; and (4) visual field defects consistent with a loss of retinal ganglion cells. Many classification schemes exist for grouping cases of glaucoma, and POAG is from the cause-based approach to glaucoma development, whereby the term ‘primary’ means that no known ocular or systemic disease appear to contribute to the disease process. Classification purists may argue that cause-based classification relates to IOP elevation rather than glaucoma development. Ideally, diagnostic confusion between cases with and without elevated presentation IOPs may be avoided by noting ‘high pressure type POAG’ where appropriate.

Paul Spry, PhD, MCOptom

PEARLS FROM THE EXPERTS

"I have always felt that the argument about which happens first, structural damage or functional loss, was a silly question. When one axon is lost, there is some function lost as well, assuming the axon was serving some purpose. The question is, can we detect the loss of one axon structurally or by the functional loss that occurred? The answer is NO, you would not expect to be able to detect the loss of an axon by inspecting the nerve, nor by testing any visual function. Well, what about 100 axons, 1000 axons, 10,000 axons, etc.? At some point you can recognize the loss, and it depends on the method used. And this may change over time, with better ways to evaluate both structure and function, so that at one time in history one method may out-perform another. Moreover, cases differ, and if a very discrete bundle is lost, you may not recognize that by structure, but be able to find a small, deep scotoma. On the other hand, with more diffuse loss, one may recognize cup enlargement, but the field may be depressed, maybe fully still in the normal range. So as glaucoma is emerging to the level of severity of clinical recognition, there may always be some cases that are first recognized by a field abnormality or change and others first recognizable by a structural abnormality or change. We see that in OHTS, that some endpoints resulted from recognizing disc change, and others with field change, and only a few in which both occurred at the same time."

Douglas R. Anderson, M.D., Professor of Ophthalmology, Bascom Palmer Eye Institute, University of Miami Miller School of Medicine

MEETING NEWS

The North American Perimetry Society (NAPS) meeting was held on September 22 and 23, 2005 in Skaneateles, New York. The main theme of the meeting was perimetry in neuro-ophthalmologic conditions. However, there were also a number of presentations directed towards new test procedures and evaluation strategies for perimetric evaluation of glaucoma, the relationship between structural and functional damage in glaucoma, sources of variability in the assessment of glaucomatous visual field loss and modeling of the mechanisms underlying glaucomatous visual field loss. The presentations were of high caliber and generated a considerable amount of discussion and debate among the attendees.

The World Glaucoma Congress (WGC) held its first meeting in July in Vienna. Never before had a meeting of this scale been attempted in a subspecialty area. Sitting in one room were individuals involved in glaucoma from countries in North and South America, Europe, Asia, Africa and Australia. One-hundred and forty individuals made up the faculty, and more than 1,500 clinicians and scientists attended the sessions. The Optometric Glaucoma Society was well represented with six members serving as faculty.

INTERNATIONAL COLUMN: GLAUCOMA MANAGEMENT DOWN-UNDER

The role of optometry in glaucoma detection and management is undergoing change in Australia. In all states optometrists have a primary care role, detecting glaucoma and referring on to ophthalmologists for diagnosis and treatment, as and when needed. However, in some states, notably Victoria, a secondary care aspect has been approved following the recent promulgation of therapeutic legislation in 1996 and its enactment in 1998. The law has allowed post-graduate certification after an approved training course, and this has been achieved by some 200 practitioners so far. The certification allows treating and monitoring glaucoma patients with confirmed disease on a co-management basis. In these cases the certified optometrists have access to, and can prescribe, all classes of topical glaucoma drugs as approved by the Minister (some drugs are not available in Australia to medicine or optometry). However, Victorian optometrists cannot provide prescriptions via the Pharmaceutical Benefits Scheme (PBS). This places the patients of certified optometrists at a significant, financial disadvantage as the government substantially subsidizes the costs of PBS drugs for diseases requiring chronic intervention e.g. in some cases, a PBS script can be 20-25% of the non-PBS price. Nevertheless, certified Victorian optometrists are now much more integrated in glaucoma care by working alongside ophthalmologists. Their major role is in monitoring suspects or patients with active disease and suggesting treatment interventions when progression is detected. Under this co-management model, the managing group (optometrist/ophthalmologist) agree on a target pressure and intervention modality and patients are monitored for their capacity to achieve and sustain this target with minimal change in nerve or fields.

Many of the other states are presently negotiating, or have recently finalized their therapeutic laws, although independent glaucoma management is not an outcome in many of these jurisdictions. Undergraduate courses are being implemented to educate students to this new standard and the first therapeutically endorsed clinicians will graduate from the University of Melbourne at the end of 2006.

Algis Vingrys, PhD

CLINICAL TRIAL REVIEW

Baseline topographic optic disc measurements are associated with the development of primary open-angle glaucoma. The Confocal Scanning Laser Ophthalmoscopy Ancillary Study to the Ocular Hypertension Treatment Study. (Zangwill et al, Arch Ophth 123, Sept 2005).

This paper reports on 438 patients enrolled in the Ocular Hypertension Treatment Study (OHTS) who had been examined with the Heidelberg Retina Tomograph (HRT1). The authors report a statistically significant association between baseline HRT status (using several optic disc analyses such as the Moorfields Regression Analysis, MRA), and subsequent development of glaucoma according to the criteria of the OHTS study (reproducible glaucomatous visual field loss and clinically apparent optic disc abnormality, confirmed by two independent masked readers). Of the 36 participants who developed overt glaucoma during the follow-up, 10 (28%) had an abnormal result with the Moorfields Regression Analyses (MRA) at baseline. Of those 402 participants who did not develop overt glaucoma, only 32 (8%) had an abnormal MRA at baseline.

Comments: The results show that HRT optic disc imaging is sensitive to early damage that may not be clearly evident on clinical examination. However, the predictive value associated with a positive baseline examination was only 14%. While HRT imaging of the optic disc can certainly support decision-making in clinical practice, the real utility of imaging technologies in the care of patients with ocular hypertension may lie in their ability to detect subtle changes over time-changes that are pathognomic for glaucoma and independent of the large spectrum of optic disc appearance in healthy subjects. Longitudinal data from the CSLO Ancillary Study of the OHTS, and from other centres, will shed more light on this issue.

Paul Artes, PhD, MCOptom

PERSISTENCE OF DRUG USAGE IN GLAUCOMA CARE

We are all intimately familiar with the issue of "compliance" being the weak link in the glaucoma care chain. However, the bigger picture centers around "persistency;" that is, do our patients persist in returning to the pharmacy to continue to purchase their medicines? A recently published study on this issue reports: "Nearly one-half of the individuals who had a glaucoma prescription discontinued all topical ocular hypotensive therapy within six months, and just 37% of these individuals recently had refilled their initial medication at three years after first dispensing." This is abysmal, and we, as a profession, need to be cognizant of such poor patient performance so we can mount an aggressive and sustained effort to improve our care and thus, our patient’s quality of life.

This article, published by Nordstom, et. al. in the October AJO, has several quotes worthy of comment:

(1) "Overall, persistence was marginally greater among patients with diagnosed glaucoma than patients with suspected glaucoma."

Comment: It may be that many patients are more committed to treating a disease (potentially blinding, at that) than modifying a risk factor. Either way, a competent optometrist would never prescribe frivolously, and therefore, sound, consistent education and motivation should (in theory) produce equally good compliance and persistency.

(2) "… latanoprost, which constituted greater than 80% of the prostaglandin use in the present data, has one of the highest co-payment costs of any topical hypotensive. Thus, better persistence and adherence with prostaglandins occurred despite the disincentive of greater cost."

Comment: While cost is always considered a major deterrent to medicine use, this particular study did not find such to be the case. Perhaps, if patients are properly educated (and motivated by their doctor), then cost (for most patients) is not a major cause for poor persistency. It is our opinion that a compassionate, well-trained optometric physician can achieve a high rate of compliance and persistency.

(3) "…individuals who already stayed on treatment for some duration are more likely to stay on medicine than the average patient who is just starting treatment."

Comment: We wholeheartedly agree. If you can get patients "habituated" to daily use of any medicine for several months, we have found that most of these patients do very well over the years. The key is to follow them closely for the first several months.

(4) "Research is needed to find ways to improve on [persistency]. Although physicians must monitor and encourage proper medication use among patients with glaucoma or ocular hypertension, we always need to evaluate novel approaches to help patients with this process if we are to improve on the currently poor persistence and adherence that are documented in this report."

So in summary, that there is certainly a problem in the management of patients with glaucoma and ocular hypertension is clear. We are convinced that with ongoing educational and motivational efforts on the part of astute, caring optometrists, we can make a substantial difference in our patients’ adherence to their prescribed therapy and quality of life.

Randall Thomas, OD, Ron Melton, OD

1. Nordstrom, B. L., et. al. "Persistence and Adherence With Topical Glaucoma Therapy." American Journal of Ophthalmology, Vol. 140, No. 4. October 2005.

NEWS ITEM The Essential HRT Primer has been released and is available free of charge from Heidelberg Engineering, inc. The hard cover book was edited by Murray Fingeret, John Flanagan and Jeffrey Liebmann with chapters by Alfonso Anton, Balwantray Chauhan, Jack Cioffi, Ted Garway-Heath, Chris Girkin, Chris Hudson, Chris Johnson, and Linda Zangwill. The foreword was written by Bob Weinreb. The Primer is an excellent book for anyone interested in imaging as it covers the role of imaging in the management of glaucoma, the concept of structure and function as well as the evaluation of the HRT printout and data. The book is available by contacting Heidelberg Engineering at ContactUSA@heidelbergengineering.com.

CLINICAL NEWS QUESTIONS & ANSWERS

In future issues this section will contain answers and comments from our editorial board that relate to questions from our readers. If you would like us to answer a clinical question, please send it to paul.spry@ubht.swest.nhs.uk. The questions can concern anything related to glaucoma, for example analysis of an optic nerve image, optic disc, a challenging case or side effect of a medication. We welcome your questions and we will try to address as many as possible in each issue.

Editor in Chief Paul Spry PhD MCOptom Associate Editors Brad Fortune, OD, PhD Shaban Demirel, BScOptom, PhD Algis Vingrys BScOptom, PhD

Editorial Board Douglas Anderson MD Paul Artes PhD MCOptom Dick Bennett OD Murray Fingeret, OD Ron Harwerth, PhD Chris Johnson, PhD Tony Litwak, OD John McSoley, OD Ron Melton, OD Bruce Onofrey, OD, RPh Leo Semes, OD Randall Thomas, OD Thom Zimmerman, MD, PhD   Art/Production Director Joe Morris Project Coordinator Janice Miller