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Top-Ten American Glaucoma Society Meeting 2002

February 28th - March 3rd, 2002, San Juan, Puerto Rico

Jeff Liebmann

• A case-control comparison of the clinical characteristics of glaucoma and ocular hypertensive patients with and without the myocilin GLN368stop mutation
  Graul TM, Kwon YH, Zimmerman B, Kim CS, Sheffield VS, Stone E, Alward WLM
  Molecular genetics has the potential to revolutionize the diagnosis and management of glaucoma. To date, a variety of mutations have been identified in glaucoma patients. Graul et al., in a paper delivered by Alward, sought to determine whether patients with a specific defect, the myocilin Gln38stop mutation, are at increased risk for disease progression compared to matched glaucoma subjects without this mutation. They found no statistical differences between the groups with respect to age at onset, peak IOP, visual field defect, and need for, and time to, laser trabeculoplasty or filtering surgery. These results suggest that screening for this mutation does not have clinical importance at the present time.
• Evidence for age of onset heterogeneity in adult-onset POAG: support for using phenotypic stratification in linkage analysis
  Allingham R, Wiggs JL, LaRoque KR, Broomer B, Graham FL, Hauser MA, del Bono BA, Bailey R, Haines JL, Pericak-Vance MA
  One of the difficulties encountered in the field of glaucoma genetics is the heterogeneity of adult-onset primary open angle glaucoma. In this study, Dr. Allingham and colleagues evaluated 86 POAG families with at least 2 or more affected individuals. Families were stratified by the following criteria: age of onset, maximal IOP > 29, extensive field loss or history of filtering surgery, among others, and linkage analysis was performed on candidate regions. Of these criteria, only age of onset gave increased evidence for linkage to the chromosome 15 candidate region. These results support the concept that stratification based on age of disease onset may be a useful way to differentiate POAG subsets.
• Pilot study on the effects of drying on central corneal thickness
  Challa P, Greenman H, Stinnett S, Epstein D, Herndon L
  Measurement of intraocular pressure is affected by the thickness of the cornea. Prior work by this group and others suggests that increased corneal thickness results in an artifactitious elevation of IOP during Goldmann applanation tonometry and that in eyes with relatively thin corneas applanation tonometry may underestimate true IOP. In this study, the authors measured corneal thicknesses at 15-second intervals following instillation of proparacaine topical anesthesia and found statistically significant thinning with drying. Given the strong relationship between corneal thickness, IOP, and glaucoma risk, care should be taken to avoid excessive corneal drying immediately before applanation tonometry.
• Comparison of glaucomatous visual field defects using standard Full Threshold versus the Swedish Interactive Threshold Algorithms (SITA Standard and SITA Fast)
  Budenz DL, Rhee P, Feuer WJ, Johnson CF, McSoley, J, Anderson, DR
  New algorithms to assess visual function in glaucoma should be compared to existing strategies to determine reproducibility and reliability. This study compared the severity, size, and depth of glaucomatous visual field defects in 77 patients who performed standard full-threshold, SITA-standard, and SITA-fast visual fields using a 30-2 strategy on the Humphrey Field Analyzer II. Mean deviations were approximately 1 db worse using the full-threshold strategy compared with SITA-standard. In general, glaucomatous visual fields were less severe using the SITA-standard and SITA-fast algorithms. Clinicians should be aware that SITA-standard uses a full-threshold strategy and that SITA-fast does not.
• OCT Optic Nerve Head Assessment: Comparison with HRT
  Schuman JS, Farra T, Mattox C, Hertzmark E, Kolbe AH
  Assessment of cup-disc ratio has been an integral part of the examination of the optic nerve in glaucoma. Although much is known about the ability of optical coherence tomography to assess the thickness of the nerve fiber layer, little is known about its ability to evaluate optic disc contour. In this project, Dr. Schuman and colleagues compared automated measurement of cup-disc ratio using confocal scanning laser ophthalmoscopy (Heidelberg Retina Tomograph) and OCT in 189 eyes of 112 patients. Significant correlations were observed for disc area, cup area, cup volume, cup/disc area ration, rim area, rim volume and horizontal rim width. These correlations were achieved without the creation of a contour line or other observer input and suggest that it may be possible to generate these indices without subjective observer evaluation of the optic disc border.
• What is the risk of developing pigmentary glaucoma from PDS?
  Johnson DH, Siddiqui Y, Hodge H
  Pigmentary dispersion syndrome (PDS) is characterized by the classic triad of midperipheral iris transillumination defects, Krukenberg spindle, and increased, homogeneous trabecular pigmentation and may be accompanied by elevated intraocular pressure with or without glaucomatous damage. In this retrospective, population-based study in Olmstead County, Minnesota, USA, 119 patients with PDS without ocular hypertension were assessed over a 23-year period. Of these patients, 13% developed PG or PDS with elevated IOP requiring therapy at 5 years and 23% at 15 years. An additional 26 patients were found to have pigmentary glaucoma at the time of diagnosis during this period.
• Cylindrical tubular structures spanning from trabecular meshwork across SC: Laboratory studies with SEM, TEM & Tracers correlated with clinical findings
  Johnstone MA, Stegmann R, Smit BA
  The authors identified cylindrical structures spanning the trabecular meshwork and Schlemm's canal in vivo and histopathologically. These tube-like structures demonstrated endothelial channels originating from the trabecular meshwork, with their attachments to the corneoscleral wall of the canal and opening at their distal end. Viscoelastic dissection demonstrated diaphanous cylindrical structures that could be seen with the dissecting microscopy. The structures were highly compliant and could be stretched to twice their resting length. These structures could be identified inn clinical videotapes of nonpenetrating surgery and may play an important role in the movement of aqueous to Schlemm's canal.
• Aqueous shunt devices in pediatric glaucomas under two years of age.
  Beck AD, Freedman SF, Kammer J, Jin J
  The management of unusual or secondary pediatric glaucomas remains problematic. In this retrospective study, 44 eyes of 31 patients less than 2 years of age underwent tube-shunt implantation (30 Ahmed, 14 Baerveldt). Mean age was 7.3 months with a preoperative mean IOP of 34.0 mmHg on an average of 2.5 medications. Mean IOPs were 18.2, 19.1 and 18.5 mmHg at 1, 2, and 3 years of follow-up. Cumulative success at 2 years was 80.6%. Complications were common, with 21 eyes requiring a subsequent surgical procedure. The authors concluded that tube-shunt implantation is a useful adjunct in the management of pediatric glaucomas, but that surgical re-intervention if often necessary.
• Iridociliary apposition in plateau iris syndrome remains unchanged after cataract extraction
  Tran HV, Ishikawa, H, Liebmann JM, Ritch R
  An abnormal iridociliary relationship is thought to underlie plateau iris syndrome. In this study, the authors used ultrasound biomicroscopy before and after cataract extraction in 7 eyes with plateau iris to determine the effect of surgery on the iridociliary relationship. Mean patient age was 74 years and mean refractive error was +2.7 diopters. Iridociliary contact was present before and after cataract extraction in all eyes. Anterior chamber depth and angle opening distance were greater following cataract extraction (all p<0.05). The authors concluded that persistent iridociliary contact following cataract surgery in these eyes is primarily related to an intrinsic abnormality of the iridociliary relationship and not dependent on an abnormal lens or zonular position.
• Risk factors of hypotony maculopathy
  Fannin LA, Budenz DL, Schiffman J
  The medical records of 186 patients with ocular hypotony following glaucoma surgery were reviewed in this retrospective case series to determine risk factors for hypotony maculopathy. Mean age for eyes with maculopathy was 50.5 years vs. 70.7 years for those eyes without maculopathy (controls). Maculopathy was more frequent in eyes with myopic and in eyes undergoing initial surgery and had a lower frequency of choroidal effusion than non-maculopathy controls. In conclusion, the authors confirmed previous reports that younger age, male gender, myopia, and primary filtering surgery are risk factors for the development of hypotony maculopathy. A relationship between the use of antifibrosis chemotherapy and laser suture lysis was not identified.