Top-Thirteen From the Optometric Glaucoma Society Meeting

December 6, 2005, La Jolla, California, USA

Murray Fingeret, John Flanagan and Michael Patella

The fourth annual meeting of the Optometric Glaucoma Society took place in La Jolla, California on December 6, 2005. John Flanagan, PhD was the meeting chair. The meeting was organized with the support of Robert N. Weinreb, MD and the faculty from the Glaucoma Service, University of California, San Diego. Stephen Drance was the honoree, and faculty included Chris Johnson, Felipe Medeiros, Pam Sample, Linda Zangwill, John Liu, James Lindsey, Jonathan Crowston, Michael Goldbaum, and Rob Duncan.

• In a retrospective of the Normal Tension Glaucoma (NTG) Study we were reminded that 50 percent of the NTG patients achieved a 30 percent pressure reduction without surgery.
• The NTG Study showed that a 30 percent IOP reduction favorably affected the course of the disease, once cataracts were accounted for. Cataracts occurred in 11 of the 79 untreated patients and 23 of the 66 treated patients.
• In the past few years we have discovered that measures of structure and function do not seem to agree either temporally or spatially. They are likely not telling us the same thing. This discrepancy is probably adversely affecting our clinical performance.
• It is entirely possible that the so-called functional reserve is an artifact created by the discrepancy between structural and functional measurements. Studies have shown that the relationship between functional loss and the structure of the neuroretinal rim is linear provided the scales are matched, i.e. both logarithmic or both linear.
• In the OHT Study structural and functional indices were considered predictive factors but not risk factors for glaucoma since the definition of glaucoma is based on characteristic structural and functional damage. However, these predictive factors may actually be signs of early glaucoma not yet defined as glaucoma endpoints by the OHTS reading centers.
• The CSLO Ancillary Study to the OHTS, found that after adjusting for disc area, none of the differences in optic disc topography between African-Americans and other participants remained statistically significant. Perhaps disc size and not  race is the determining difference between African-Americans and other ethnicities. Regardless, these results highlight the need to consider optic disc size when evaluating the appearance of the optic disc in glaucoma.
• Within the five-year follow-up period of the CSLO Ancillary Study to the OHTS, the positive predictive value of CSLO indicies ranged from 14 percent for Heidelberg Retina Tomograph classification and Moorfields Regression Analysis global classification, to 40 percent for Moorfields Regression Analysis in the temporal superior sector.
• SWAP has been found to have many advantages over standard perimetry. It is more sensitive, particularly for glaucoma. It is predictive of future visual field loss three to five years earlier. The prevalence of SWAP deficits is greater in high-risk suspects. Progression is greater than for standard perimetry. Defects are larger.
• However, SWAP also has disadvantages. It is more affected by cataract (although ways of overcoming this obstacle have been developed), more variable than standard perimetry, is difficult for some patients, and the test procedure has a limited response range.
• A series of prevalence studies have confirmed what many researchers suspected sixty years ago. Primary open angle glaucoma is the leading cause of blindness in African Americans. Visual impairment associated with POAG is more frequent in African Americans and progresses more rapidly. The disease appears on average ten years earlier in blacks than in other races. Ocular hypertension occurs twelve years earlier in blacks and is more likely to progress to POAG.
• There are many ways to classify clinical data. These methods can be split into statistical classifiers and machine classifiers. Statistical classifiers are constrained by assumptions about the data. However, machine learning classifiers are more adaptive. They can define class boundaries that adapt to the peculiarities of a specific data set, and out-perform statistical classifiers.
• The concept of risk assessment is new to glaucoma and allows an evidence based approach to determine which individuals with ocular hypertension are at greatest risk of converting to glaucoma. This allows therapy to be directed to those at greatest risk and monitor those at lower levels.
• Nocturnal IOP, in which the intraocular pressure is measured over a 24-hour period with the measurements taken in the most common habitual position for the time period find that IOP is often highest late at night in both normals and glaucomas. This is different from conventional wisdom.