Eyeworld

69 July 2015 EW MEETING REPORTER within ocular tissues. Low ocular perfusion pressure (OPP) may rep- resent the historical vascular theory of glaucoma pathogenesis: Elevated IOP relative to blood pressure reduc- es ocular tissue perfusion and leads to an ischemic state. Likewise, the difference between IOP and cere- brospinal fluid pressure generates a translaminar pressure gradient that may represent the historical me- chanical theory of glaucoma. Editors' note: The physicians have no financial interests related to their comments. Highlights from the Optometric Glaucoma Society symposium Our understanding of the relation- ship between IOP and glaucoma is limited by our inability to character- ize IOP behavior over time. John Flanagan, PhD, Berkeley, Calif., pointed out that new tools for continuous IOP monitoring are rapidly approaching. Among these is a contact lens-based system that will permit measurement of IOP over a 24-hour period. In early studies, the device is reasonably well tolerated but is associated with some red- ness, discomfort, and some patients cannot tolerate it for a full 24 hours. He pointed out that like the cornea, the sclera also demonstrates circa- dian variability in curvature asso- ciated with IOP change, and trans- scleral-based IOP monitoring may offer advantages over transcorneal approaches. Ben Gaddie, OD, Louisville, Ky., pointed out that corneal hysteresis is emerging as an important risk factor for both the development and the progression of glaucoma. Corneal hysteresis is a measure of the biome- chanical properties of the cornea. Hysteresis can be measured with a modified noncontact tonometer, the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, N.Y.). Hysteresis has been shown to be associated with the rate of progression over time, and inter-eye differences in hysteresis may help explain asymmetric glaucoma. The measurement is now a reimbursable procedure in the United States. Editors' note: Dr. Gaddie has financial interests with Reichert Ophthalmic In- struments. Dr. Flanagan has no finan- cial interests related to his comments. Glaucoma in the developing world The WGA has dedicated organiza- tional resources to explore solutions to the growing problem of glauco- ma in Africa and other developing regions of the world. Two symposia defined the magnitude of this prob- lem and sought solutions to prevent glaucoma blindness in these under- served regions. The number of people afflict- ed with glaucoma worldwide is expected to exceed 100 million by 2040, according to Neeru Gupta, MD, PhD, Toronto. Of these, nearly 20 million will be in Africa. This burden of disease is unmanageable, particularly in parts of rural Africa where the ratio of people to oph- thalmologists is 7 million to 1. The problem is further compli- cated by the nature of African glau- coma. "Glaucoma affects Africa on a scale unparalleled in the world," said Olusola Olawoye, MD, Nigeria. She pointed out that glaucoma affects Africans at an early age, is character- ized by high IOP, progresses rapidly, and presents in advanced stages, with many patients already blind in 1 eye at the time of diagnosis. Solutions to this problem have been elusive. Medications are unaffordable and surgery requires experienced surgeons. Laser trabec- uloplasty shows some promise in patients of African descent. Ultimately, preventing glauco- ma blindness will require a multi- pronged approach, according to Alan Robin, MD, Baltimore. Identifying optimal treatment ap- proaches, developing infrastructure to deliver this care, and improving screening strategies to find the 90% or more of afflicted people who remain undiagnosed in undeveloped regions will be needed. Editors' note: The physicians have no financial interests related to their comments. Glaucoma treatment strategies The reduction of IOP can prevent glaucoma in patients with ocular hy- pertension and prevent progression in established glaucoma patients. Which glaucoma suspects are most likely to benefit from preventive therapy? The risk calculator devel- oped from the combined data of the Ocular Hypertension Treatment Study and the European Glaucoma Prevention Study is a validated tool to assist in this clinical assessment. James Brandt, MD, Sacramento, Calif., pointed out that this tool can help identify those who should and should not be treated, and "will help us avoid treating patients with low risk of developing significant vision loss in their lifetime." "In clinical studies," said Robert Fechtner, MD, Roseland, N.J., "pa- tients treated to a target IOP fared better than those without a target IOP." Target IOP is a clinical judg- ment based on risk factors such as IOP, stage of disease, life expectancy, and status of the fellow eye. Selection of primary therapy should be tailored to the needs and desires of the individual patient. Medications remain the typical first-line approach, however "laser trabeculoplasty is a reasonable first option for many patients, and can provide a 25–30% reduction in IOP," according to Jeffrey Liebmann, MD, New York. Editors' note: The physicians have no financial interests related to their comments. continued on page 70 IOP variability in clinical practice Fluctuations in IOP can occur throughout the day and night, and IOP also demonstrates variability from day to day, according to Felipe Medeiros, MD, University of Cal- ifornia, San Diego. "Two-thirds of untreated glaucoma patients exhibit their peak IOP during the nocturnal period," he said. This complicates management, as these peaks are essentially undetectable in routine clinical practice. Emerging tools will assist us in more fully characterizing 24- hour IOP patterns in our patients. Luciano Quaranta, MD, Brescia, Italy, reviewed the devices that have been developed to provide contin- uous IOP assessment. Of these, the Triggerfish (Sensimed, Lausanne, Switzerland) has garnered much attention. It functions as a strain gauge and infers IOP based on changes in corneal curvature. "It does not provide absolute IOP values but does inform us of IOP fluctuations," he said. The significance of IOP fluc- tuation remains hotly debated. In reviewing the current literature, Tetsuya Yamamoto, MD, Japan, observed, "Some studies have found a relationship between IOP vari- ability and progression, and others have not." Making clinical decisions based on IOP variability may be pre- mature. While it would be tempting to treat a patient with known IOP peaks more aggressively at night, he said that most people—whether they have glaucoma or not—have IOP el- evations at night, and whether these contribute to glaucoma progression remains unknown. Editors' note: Dr. Medeiros has finan- cial interests with Sensimed. The other physicians have no financial interests related to their comments.

• Cover