Experts from around the globe join for first World Glaucoma Congress

VIENNA – The World Glaucoma Congress (WGC) held its first meeting in July in Vienna. Attendees included members and guests from the Association of International Glaucoma Societies (AIGS). The AIGS is an umbrella organization comprising the world’s glaucoma societies, of which the Optometric Glaucoma Society is a member. The mission of the WGC was to convene the world’s different glaucoma organizations under one roof.

According to the AIGS Web site, “Glaucoma needs a global meeting, and glaucoma societies need to get together to create global communication. AIGS is in the position to provide the highest quality meeting following its own Guidelines on Quality of Glaucoma Meetings, Guidelines on Reporting and Publishing and the Code of Practice, avoiding commercialization. Glaucoma Societies and Glaucoma Industry Members have similar ethical scientific standards. The WGC could serve as an example for other meetings. The WGC will be a powerful stimulus for progress in glaucoma worldwide.”

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. Each would bring a unique perspective on diagnosing and managing glaucoma. One-hundred 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 seven members attending and six selected to be part of the faculty. Information on the meeting is available at http://www.globalaigs.org/WGC2005.

Global impact, diagnosis, treatment

Thomas L. Lewis, OD, PhD, FAAO, president of the Pennsylvania College of Optometry had these thoughts after attending the meeting. “Having recently attended the World Glaucoma Congress in Vienna, I walked away with a deeper and better understanding of the most recent and relevant information on the etiology, global impact, diagnosis and treatment of the glaucomas. There was the chance to interact with thought leaders, top clinicians as well as scientists from around the world, which was very stimulating.

“Several interesting talks were directed to the pathophysiology of primary open-angle glaucoma (POAG), some secondary glaucomas and angle-closure glaucoma,” he continued. “Issues related to ultrastructural and biomolecular changes in the anterior chamber and optic nerve were emphasized. The impact of blood flow to the optic nerve and neuroprotection were debated with regard to the role they play in the development of the optic neuropathy known as glaucoma. The recent models relating to risk assessment were reviewed. Global risk assessment including the development of risk calculators is a hot issue related to the early diagnosis and treatment of the disease.

“For me, it was quite enlightening to understand the global impact of angle-closure glaucoma,” Dr. Lewis said. “I knew that angle-closure glaucoma was the major form of the disease in certain parts of the world, especially in Asia, but being primarily influenced by the characteristics of glaucoma in North America, I was duly impressed by the worldwide view of the disease.”

Circadian variability, ISNT rule two themes

Circadian variability of intraocular pressure was a theme in the initial presentations of the congress. Several discussions addressed the role of 24-hour IOP monitoring with regard to the rate of progression and titrating treatment.

Much of the first day of the Congress discussed the relationships between structure and function. The “ISNT rule” and its application to evaluating the optic nerve head was described in detail. The ISNT rule is simple: in a healthy individual, the width of the optic nerve rim tissue varies depending upon the segment. It is widest inferiorly, then superiorly, nasal and temporal. As one begins to develop glaucoma, the ISNT rule breaks down, as the nasal or temporal sectors may now appear thickest.

The emphasis in disc evaluation included evaluating for the optic disc size, the neuroretinal rim thickness and color, the parapapillary area, retinal nerve fiber layer and inspection for optic disc hemorrhages.

Advances in therapy: EGPS

The second day of the congress moved into therapy. A review of the recent clinical trials from the United States and Europe emphasized the significant number of patients in the “treatment arm” of these studies that showed progression.

The European Glaucoma Prevention Study (EGPS) was discussed in detail. The EGPS was similar to the Ocular Hypertension Treatment Study in that it evaluated ocular hypertension and frequency of conversion to glaucoma. Several differences between studies existed. For example, the EGPS used only dorzolamide in the treatment arm and also had a placebo-controlled arm.

The unexpected EGPS results showed the placebo and therapy groups to have similar reductions in IOP (approximately 17%), which had not been reported previously. This led to the conclusion that therapy (for this study) was not useful in preventing glaucomatous damage.

The EGPS had a large dropout rate, which helped explain the results. In addition, the possibility of the phenomenon of regression to the mean may have had an unduly strong influence. Either way, the EGPS shows the difficulty in designing and carrying out complex clinical trials.

Harwerth study: contrast sensitivity reduction

Brad Fortune, OD, PhD, a scientist at Devers Eye Institute, Portland, Ore., commented after the meeting: “Ron Harwerth’s data were very exciting to me. He demonstrated a greater reduction in contrast sensitivity (CS) for higher spatial frequencies (as compared with lower spatial frequencies), regardless of field location/eccentricity, in the high-IOP experimental model of glaucoma in non-human primates. Perhaps more importantly, this loss of CS was present prior to sensitivity loss as measured using standard automated perimetry (SAP).

“These findings help to reconcile long-standing controversies in the field of glaucoma and electrophysiology,” Dr. Fortune continued. “Further, they help explain why so many patients complain about their vision being reduced (including central vision), despite having normal foveal (or near central) point thresholds on SAP.”

The poster, “Spatial Contrast Sensitivity Defects from Experimental Glaucoma,” received a top 10 award.

Posters from around the world

The poster section provided a great deal of new information, and work was displayed from around the world. These selected summaries represent highlights of the poster sessions. The abstracts are available online at http://www.globalaigs.org/WGC2005/pdf/posters.pdf.

Gonioscopic abnormalities

Researchers in India (Lingam and colleagues) found clinically significant gonioscopic abnormalities in nearly 15% of 3,880 eyes that were part of a population–based glaucoma study. Although the epidemiology of glaucoma is different in India than in the United States, this report underscores the necessity of gonioscopic examination in all glaucoma patients.

A report from the Blue Mountains Eye Study in Australia (Healey and colleagues) found a higher incidence of optic disc hemorrhages (DH) than previously reported (1.2% vs. 0.4% in the Beaver Dam Eye Study). More than 2,200 eyes were examined photographically by expert graders over a 5-year follow-up. The cohort consisted of individuals not known to have any eye disease at the outset of the study. The authors suggest that the transient nature of DH contributes to their underestimation.

Robin and colleagues reported that 25% of their glaucoma patients were also taking at least four systemic medications. They suggest that this represents a significant burden that may negatively affect compliance.

In a Japanese study (Kogure and colleagues), investigators failed to find a relationship between increased dosing and decreased quality of life (QOL). Factors reducing QOL included glaucoma duration and visual acuity in the better seeing eye.

A group from London (Dahlmann) has shown for the first time that human Tenon fibroblasts (present subconjunctivally) are involved in postoperative scarring. Their results suggest a mechanical response to cell signaling. The implication is that modulation of the response may offer a more predictable and favorable outcome following trabeculectomy.

Corneal thickness changes

Long-term corneal thickness changes were reported secondary to prolonged topical steroid use. Satara and colleagues in Japan measured the central corneal thickness (CCT) of 65 eyes in which topical steroids were used for an average period of 3 years. They found that, compared to an age-matched control group, mean CCT was about 25 µm less in the topical steroid group. Implications for chronic steroid users are the dual risks of underestimation of IOP in thinner corneas and the potential for elevated IOP due to a steroid response.

The risk factor of CCT was highlighted by the Ocular Hypertension Treatment Study. Domingues and colleagues found that thinner CCT correlated with thinner retinal nerve fiber layer (measured by ocular coherence tomography) in 424 eyes with glaucoma by approximately 25 µm as compared to a control group. Additionally, the patients with thinner CCT and retinal nerve fiber layers also had larger cup-to-disc ratios.

Boehm and colleagues from Germany reported that Tono-pen (Medtronic Ophthalmics, Jacksonville, Fla.) readings were less influenced by CCT as compared to Goldmann tonometry readings.

Doyle and colleagues from France found a greater influence on measured IOP by Pascal Dynamic Contour Tonometry (DCT, Ziemer Ophthalmics, St. Petersburg, Fla.) in thin corneas. Repeatability was excellent for both applanation and DCT. Approximately 3 mm Hg difference was found for corneas with a normal mean CCT (520 to 580 µm) vs. those with a thin CCT (< 520 µm). For corneas thicker than 580 µm, little difference was found between applanation-measured and DCT.

Chris Johnson, Stuart Gardiner and Shaban Demirel’s poster on modeling changes in the variability of perimetry results with sensitivity received an award for top 10 posters. In this study, the authors examined the visual fields of 63 suspected glaucoma patients, testing them five times in a month. From these data, they created a model that found that the rate of sensitivity decline, the percentage of false positives and the starting position of the test procedure greatly affected variability relationships.

Performance and diagnostic testing

Kasahara and colleagues from Brazil examined the issue of whether music may improve patients’ ability to perform perimetry. Patients were naïve to perimetry when placed in one of two groups: the first listened to selections from Mozart (Sonata for Two Pianos in D Major) before performing perimetry, while the other group did not. The authors noted that this approach has improved subjective responses for other medical testing. They found significantly fewer fixation losses, false positives and false negatives compared with a group not exposed to the music.

Murray Fingeret, OD, in an investigation of confocal scanning laser tomography (HRT II, Heidelberg Engineering, Vista, Calif.), found that the instrument’s ability to correctly label individuals as having glaucoma or being normal varied based upon the patient’s optic disc size. The instrument performed best when the disc size was within the statistically normal range.

In a blast from the past, Rodriquez used the water-drinking test (WDT) in two groups of POAG patients — stable and progressing. He found that patients responded similarly when they consumed a smaller volume (1/2 liter): stable eyes had about half the IOP elevation than the progressing eyes.

OHTS gave us guidance regarding risk for conversion from ocular hypertension to glaucomatous damage based on structural parameters (CCT, IOP, cup-to-disc). Analyzing additional data from the OHTS, Zangwill and colleagues reported that confocal scanning laser ophthalmoscopy (HRT II) parameters provide additional information. Larger cup-to-disc area ratio, mean cup depth, mean contour height, cup volume, reference plan height and smaller rim area, rim to disc area and rim volume predicted POAG development.

Migraine in glaucoma patients

Two studies looked at the association of migraine and glaucoma. From Serbia, Hentova-Sencacic reported that patients with a history of migraine were more likely to have progressive visual field defects in POAG, and German investigators (Gramer and colleagues) reported that migraine is more prevalent among normal-tension glaucoma (NTG) patients than POAG.

Field progress in ODD vs. NTG

Visual field progression among patients with optic disc drusen (ODD) was addressed in a study from Germany. Schargus and colleagues compared a group with ODD to one with NTG. Patients with ODD have faster initial visual field progression than those with NTG. The investigators emphasized that it was impossible to differentiate visual field progression in patients with ODD associated with glaucoma, and that visual field progression may be due to the ODD and not inadequate glaucoma therapy.

Problems with medication administration

Patient-reported problems with glaucoma medications were surveyed by a team from the Wilmer Eye Institute in Baltimore. Robin and colleagues reported on patients from three practices, the majority of whom (76%) used two glaucoma medications. Patients reported an average of 2.54 problems with their medications.

The most-to-least frequent were drop administration, cost, reading the medication label, side effects and remembering to dose. Patients admitted to missing doses and to waiting less than 3 minutes between doses in multiple-dosing regimens.

Prostaglandin analog studies

Edward and colleagues reported in a study from the University of Illinois, Chicago, histopathological periocular skin changes secondary to topical bimatoprost. The significance of this report is that the dermal melanogenesis from prostaglandin use appears to be similar to the mechanism of dermal melanogenesis from UV exposure. They found no evidence of melanocyte proliferation or prostaglandin-induced inflammation in the specimens examined.

Chinese investigators (Liang and colleagues) looked at the IOP response of latanoprost in patients with chronic angle-closure glaucoma. In eyes with functional trabecular meshwork, IOP response was positive to latanoprost, but in eyes with complete closure, IOP did not decrease. This suggests that latanoprost may lower IOP by its effect on the trabecular meshwork as well as the well-known uveoscleral pathway.

The WGC was an exciting meeting that explored new methods of glaucoma development and treatment. Most importantly, those in attendance gained an appreciation of the different way glaucoma presents around the world.

The pervasiveness of angle-closure glaucoma was emphasized and led to the realization that glaucoma is made up of many different entities. In the United States, we deal most commonly with one form, but other clinicians deal with very different forms that are all labeled glaucoma.

For Your Information:

• Murray Fingeret, OD, FAAO, is chief of the optometry section at the Department of Veterans’ Affairs Medical Center in Brooklyn and Saint Albans, N.Y., and a professor at SUNY College of Optometry. He is also a member of the Primary Care Optometry News Editorial Board. He may 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: murrayf@optonline.com.
• Leo P. Semes, OD, FAAO, is an associate professor of optometry, University of Alabama at Birmingham and a member of the Primary Care Optometry News Editorial Board. He may be contacted at 1716 University Blvd., Birmingham, AL 35294-0010; (205) 934-6773; fax: (205) 934-6758; lsemes@icare.opt.uab.edu.
• Thomas L. Lewis, OD, PhD, FAAO, is president of the Pennsylvania College of Optometry. He can be reached at 8360 Old York Rd., Elkins Park, PA 19027; (215) 780-1280; fax: (215) 780-1289; e-mail: tom@pco.edu.
• Brad Fortune, OD, PhD, FAAO, can be reached at Discoveries in Sight, 1225 NE 2^nd Ave., Portland, OR 97232; (503) 413-1198; fax: (503) 413-5179; e-mail: bfortune@discoveriesinsight.org; Web site: www.discoveriesinsight.org.
• Chris A. Johnson, PhD, FAAO, can be reached at Discoveries in Sight, Devers Eye Institute, Portland, OR 97208; (503) 413-5318; fax: (503) 413-5179; e-mail: cajohnso@discoveriesinsight.org.