(IGR: 12-4) | International Glaucoma Review #

Top-ten Optometric Glaucoma Society Annual Meeting
November 15-17, 2010, San Francisco CA

An apparently non-progressive condition resembling glaucoma has been observed in young Chinese men, with a mean age of 38.9 years old, in which myopia was typically present along with tilted optic nerves and visual field defects similar to those typically seen in glaucoma. With glaucoma being defined as a progressive optic neuropathy, these individuals may be better categorized as glaucoma suspects. The relationship between myopia and glaucomatous field defects needs to be determined. These patients may suffer from an IOP-related strain on temporal nerve fibers, leading to visual field loss. (Kuldev Singh, Palo Alto)

In some populations, pseudoexfoliation accounts for 15-28% of all cases of open angle glaucoma. 50% of those with signs of pseudoexfoliative material will develop glaucoma, 40-70% of those developing glaucoma will present unilaterally and 25-40% with unilateral pseudoexfoliative syndrome will show signs of the condition in the fellow eye within 10 years. (Marlene Moster, Philadelphia)

There are currently 10 linked chromosomal sites and 3 genes associated with open angle glaucoma, and other genes have been associated with developmental glaucomas. Identifying the genetic makeup of glaucoma will help us understand the pathophysiology, allowing the development of better diagnostic tests and therapies. While genetic testing today for glaucoma is only rarely done, it may become more common when a greater number of genes have been identified. (Wallace L.M. Alward, Iowa City)

Given the well-known risks and difficulties associated with conventional trabeculectomies, tubes, and shunts, it is not surprising that the last decade has seen a major push to develop new approaches to the surgical management of glaucoma. Some of these procedures include the ExPRESS shunt, Canaloplasty, Trabectome trabeculotomy, IStent Schlemm's canal shunt, Cypass suprachoroidal shunt, Ologen collagen implant and endocyclophotocoagulation. These new procedures may significantly expand our surgical options and better allow us to tailor surgery to the individual patient. (Robert Stamper, San Francisco)

The risk of developing glaucoma when pseudoexfoliatve material is present is cumulative over time. Glaucoma occurs 5-10 times as frequently, individuals are twice as likely to convert from ocular hypertension to glaucoma, and glaucoma patients are twice as likely to progress. In one study, 16% of pseudoexfoliative eyes required treatment upon presentation and 44% of the remainder required therapy over the next 15 years. At any given IOP level, eyes with pseudoexfoliatve material are more likely to have glaucomatous damage than are eyes without it. (Marlene Moster, Philadelphia)

A relationship between cardiovascular disease, homocysteine blood levels, and pseudoexfoliative glaucoma has been observed in a series of studies. Homocysteine is an amino acid found in the blood, with higher levels being associated with a greater risk of coronary heart disease, stroke and peripheral vascular disease. (Marlene Moster, Philadelphia)

The randomized glaucoma clinical trials have significantly expanded our understanding of practical glaucoma care. AGIS, OHTS, CIGTS, & the EMGT all demonstrated the importance of IOP reduction. EMGT results also suggested that that mean IOP may be more important diagnostically than IOP fluctuation, OHTS illustrated the importance of central corneal thickness, and that risk calculation is a real possibility.CIGTS results suggested that initial medical therapy may be generally preferable to initial surgical therapy. Finally, the European Glaucoma Prevention Study (EGPS) reminded us that placebo effects may be important. (Kuldev Singh, Palo Alto)

Approximately 10% of glaucoma patients develop disabling levels of visual function loss. The risk factors for progression of open angle glaucoma include increasing age, elevated intraocular pressure, fluctuation of intraocular pressure, advanced damage at diagnosis, pseudoexfoliative glaucoma, optic disc hemorrhage, poor adherence to medical therapy, poor understanding of the disease and missed appointments. Attention to the modifiable parameters should help prevent or slow progression of glaucoma. Robert Stamper, San Francisco

Techniques used for assessment of visual function in low vision patients will differ from those used in normally sighted individuals. Visual acuity testing often requires use of very large and sometimes specialized optotypes. Visual field testing strategies may concentrate on identifying areas having absolute scotomas, rather than subtle loss. Contrast sensitivity tests may use very large targets, or may employ search and detection tasks or measure response times as a function of contrast. Low vision patients may be strongly affected by the level of ambient illumination, and standardized procedures can be used to evaluate the effects of illumination on visual acuity, contrast sensitivity and visual fields. (Ian Bailey, Berkeley)

There are a few techniques that will aid the clinician when examining the difficult to assess angle. The corneal wedge is useful to identify Schwalbe's line, especially in lightly pigmented eyes in which landmarks are not obvious. To create the corneal wedge, the light stack of the slit lamp is offset while gonioscopy is being performed with the fuzzy outer corneal line and brighter inner corneal line meeting at Schwalbe's line. It is also helpful to examine the inferior angle initially since this is often the deepest, most pigmented and easy to examine with the corneal wedge. This provides a baseline to compare with the other quadrants of the angle. (Wallace L.M. Alward, Iowa City)