Every year, the AGS Annual Meeting features presentations of the best in glaucoma research. At this year's conference, more than 440 registrants enjoyed 80 poster and 24 paper presentations as well as symposia on uveitis and glaucoma, the history of glaucoma diagnosis and treatment, and exfoliation syndrome. Lectures by Paul Kaufman, MD; Carl Camras, MD; and guest of honor Steven Podos, MD, were the highlights of the meeting. This article focuses on the presentations that I found to have the most immediate clinical relevance.

IMAGING
Panretinal photocoagulation (PRP) is known to affect all levels of the retina, including the ganglion cells. Clinicians often encounter suspicious-appearing optic nerves in such patients and must decide if the changes are glaucomatous. Field defects from the laser treatment make perimetry less helpful in making or refuting a diagnosis of glaucoma. Researchers from the University of California, Davis, presented a cross-sectional study of patients with diabetic retinopathy with or without PRP.1 Optic nerve head, peripapillary, and macular optical coherence tomography (OCT) was performed on a total of 211 eyes. Patients with PRP treatment had a thinner retinal nerve fiber layer (RNFL) in all except the temporal quadrant compared with controls. Interestingly, these eyes with prior PRP did not have any change in their optic nerve heads. Rather, pallor was often evident. My take-home message from this research is to expect RNFL thinning but not necessarily cupping after PRP. If eyes are suspicious for glaucoma, I believe baseline measurements should be repeated 3 to 4 months after laser treatment.

Racial differences are not taken into account by most currently available imaging devices. A presentation by researchers for the ongoing African Descent and Glaucoma Evaluation Study (ADAGES) underscored these important differences. Investigators tested 384 subjects without glaucoma by means of confocal scanning laser ophthalmoscopy (HRT; Heidelberg Engineering GmbH, Heidelberg, Germany), scanning laser polarimetry (GDx; Carl Zeiss Meditec, Inc., Dublin, CA), and OCT (Stratus OCT; Carl Zeiss Meditec, Inc.). Not surprisingly, the areas of the optic disc and cup were both larger in subjects of African descent compared with those of European descent. The mean cup-to-disc ratio in ADAGES subjects of African descent (by HRT) was 0.32 versus 0.20 in subjects of European descent. The rim areas were similar between groups, as were mean RNFL thicknesses (104 vs 102 µm by OCT). Interestingly, RNFL thickness was not equally distributed, with subjects of African descent having thicker superior and inferior measurements than subjects of European descent. The ADAGES group promises several future publications, and the current findings emphasize the importance of including race in normative databases (as is offered on the HRT3 and is under development for other modalities).2

RISK CALCULATION
Current risk calculators (such as the one available at http://ohts.wustl.edu/risk) can help clinicians determine the appropriate treatment of patients with ocular hypertension. These calculators are far from perfect, however, although they are based on large studies with solid data. To address other potential predictive factors from the Ocular Hypertension Treatment Study and European Glaucoma Prevention Study, researchers examined the clinical significance of baseline asymmetry. Interesting findings included the remarkable symmetry between eyes in both studies. At the 90th percentile were IOP asymmetry of 3 mm Hg, a central corneal thickness of 19 µm, a cup-to-disc ratio of 0.2, and a pattern standard deviation of 0.5 dB. Among these variables, asymmetry in IOP and cup-to-disc ratio were significant predictors of who would develop glaucoma. Limitations discussed following the presentation included the possibility that patients with a lot of asymmetry might have already had early glaucoma. This study highlighted the inherent symmetry of the human body; when eyes are highly asymmetric, clinicians' suspicions should be raised. It is not clear if asymmetry is sufficiently predictive in the Ocular Hypertension Treatment Study and European Glaucoma Prevention Study to be included in the next version of current risk calculators.3

SURGICAL COMPLICATIONS
What is the risk of hemorrhagic complications during and after glaucoma surgery in patients on anticoagulants such as coumadin or antiplatelet agents such as aspirin or Plavix (Bristol-Myers Squibb Company, New York, NY, and Sanofi-Aventis, Bridgewater, NJ)? Researchers from the University of California, Los Angeles, examined the records of 1,289 patients undergoing glaucoma surgery, including 347 eyes of patients on these medications. Patients on anticoagulant or antiplatelet aggregation therapy had a higher rate of hemorrhage than controls (10% vs 3.7%). Of those who continued anticoagulant treatment through the surgery, the risk was a surprisingly high 32%. No significant difference in the rate of hemorrhage was seen between patients who continued or discontinued aspirin or other antiplatelet agents. The researchers concluded that clinicians should work in conjunction with a medical consultant to discontinue coumadin in those patients for whom it is reasonably safe and should consider bridging treatment (eg, with low-molecular-weight heparin such as Lovenox [Sanofi-Aventis]) for individuals in whom the risk of discontinuation is too great. Stopping antiplatelet agents prior to surgery did not decrease the risk of hemorrhagic complications.4

LATEST SURGICAL TECHNIQUES
To investigate the role of endoscopic cyclophotocoagulation (ECP) in the management of patients with glaucoma, researchers at the University of Southern California treated 25 eyes of 25 patients with functioning Baerveldt-350 glaucoma drainage devices (Advanced Medical Optics, Inc., Santa Ana, CA) with 360º of ECP. At 12 months of follow-up, the mean IOP decreased from 24 to 15 mm Hg, while the mean number of medications decreased from 3.20 to 1.55. Fewer patients (n = 11) were followed to the 2-year mark, but these effects appeared to persist. No serious or devastating complications (eg, hypotony or phthisis) occurred. Only four patients lost more than two lines of visual acuity, three individuals due to corneal issues and one from cystoid macular edema. ECP would seem to provide an effective alternative to the placement of a second drainage device.5

In canaloplasty, a lighted microcatheter dilates the circumference of Schlemm's canal via the injection of a viscoelastic, and a trabecular-tensioning suture loop is then placed within the canal. Richard Lewis, MD, presented the 1-year results of a multicenter prospective trial of this technique. Of 145 patients enrolled, 112 have had successful canaloplasty. The mean baseline IOP was 23.1 mm Hg on 1.9 medications; at 1 year, the mean IOP was 15.2 mm Hg on an average of 0.3 medications. Surgical complications included hyphema (n = 6), elevated IOP (n = 4), and Descemet's tear (n = 2). The investigators concluded that canaloplasty appears to be a safe and effective surgical procedure in patients with primary open-angle glaucoma.6

In contrast, the Trabectome (NeoMedix Corporation, Tustin, CA) has a footplate that acts as a guide within Schlemm's canal, and a cutting/ablation function removes a strip of the inner wall of the canal and trabecular meshwork. This procedure is performed through a temporal corneal incision, under gonioscopic control, and may be combined with cataract surgery. Donald Minckler, MD, presented the findings of a multicenter trial with a current enrollment of more than 276 patients, 57 of whom had the surgery combined with cataract extraction. From a baseline mean IOP of 24.2 mm Hg on an average of three medications, IOP was reduced to 16.7 mm Hg at 12 months and 14.3 mm Hg at 24 months on an average of less than one medication. Intraoperative blood reflux occurred in most patients, whereas more serious complications such as persistent corneal injury (n = 1), injury to the iris (n = 4), and angle synechiae (n = 14) were less common. A high proportion of subjects (n = 51 or 18%) experienced a pressure spike of greater than 21 mm Hg on the first postoperative day. The Trabectome surgery was repeated in seven patients, and 14 (5%) required trabeculectomy or tube shunt surgery. No cases of sustained hypotony, wound leak, choroidal detachment, or loss of more than two lines of visual acuity were reported. Stated advantages of the procedure included improved efficacy over laser trabeculoplasty, fewer complications than trabeculectomy, and the preservation of the conjunctiva should additional surgery be needed.7

Geoffrey T. Emerick, MD, is Assistant Clinical Professor of Ophthalmology at the University of Connecticut School of Medicine in Farmington. He acknowledged no financial interest in the products or companies mentioned herein. Dr. Emerick may be reached at (860) 678-0202; gtemerick@gmail.com.

1. Lim MC, Tanimoto S, Furlani BA, et al. Thinning of the retinal nerve fiber layer among diabetic patients with and without panretinal laser photocoagulation: a cause of glaucomatous appearing optic nerves? Paper presented at: The 17th Annual AGS Meeting; March 2, 2007; San Francisco, CA.
2. Girkin CA, Liebmann JM, Zangwill LM, et al. The African Descent and Glaucoma Evaluation Study (ADAGES): racial differences in optic nerve structure. Paper presented at: The 17th Annual AGS Meeting; March 2, 2007; San Francisco, CA.
3. Mansberger SL, Kass MA; the OHTS group; the EGPS group. OHTS/EGPS: clinical significance of baseline asymmetry in predicting the risk of developing POAG. Paper presented at: The 17th Annual AGS Meeting; March 2, 2007; San Francisco, CA.
4. Law SK, Song BJ, Kurbanyan K, et al. Hemorrhagic complications from glaucoma surgery in patients on anticoagulation therapy or antiplatelet therapy. Paper presented at: The 17th Annual AGS Meeting; March 2, 2007; San Francisco, CA.
5. Francis BA, Kawji S, Chopra V. Endoscopic cyclophotocoagulation (ECP) in the management of uncontrolled glaucoma with prior aqueous tube shunt. Paper presented at: The 17th Annual AGS Meeting; March 2, 2007; San Francisco, CA.
6. Lewis RA, Shingleton BJ, Fellman R, et al. Canaloplasty: one year results. Paper presented at: The 17th Annual AGS Meeting; March 3, 2007; San Francisco, CA.
7. Minckler DS, Francis BA, Mosaed S, et al. Update on Trabectome for surgical treatment of open-angle glaucoma. Paper presented at: The 17th Annual AGS Meeting; March 3, 2007; San Francisco, CA.