Christopher C. Teng

β-Zone Parapapillary Atrophy and the Velocity of Glaucoma Progression

PURPOSE Beta-Zone parapapillary atrophy (PPA) occurs more commonly in eyes with glaucoma. Rates of glaucomatous visual field (VF) progression in eyes with and without beta-zone PPA at the time of baseline assessment were compared. DESIGN Retrospective, comparative study. PARTICIPANTS Two hundred forty-five patients from the New York Glaucoma Progression Study. METHODS Subjects with glaucomatous optic neuropathy and repeatable VF loss were assessed for eligibility. Eyes with a Heidelberg Retina Tomograph II (HRT) examination, at least 5 visual field tests after the HRT in either eye, optic disc photographs, and <6 diopters of myopia were enrolled. beta-Zone PPA was defined as a region of chorioretinal atrophy with visible sclera and choroidal vessels adjacent to the optic disc. Global rates of VF progression were determined by automated pointwise linear regression analysis. Univariate analysis included age, gender, ethnicity, central corneal thickness (CCT), refractive error, baseline mean deviation, baseline intraocular pressure (IOP), mean IOP, IOP fluctuation, disc area, rim area, rim area-to-disc area ratio, beta-zone PPA area, beta-zone PPA area-to-disc area ratio, and presence or absence of beta-zone PPA. MAIN OUTCOME MEASURES The relationship between beta-zone PPA and the rate and risk of glaucoma progression. RESULTS Two hundred forty-five eyes of 245 patients (mean age, 69.6+/-12.3 years) were enrolled. The mean follow-up was 4.9+/-1.4 years and the mean number of VFs after HRT was 9.3+/-2.7. beta-Zone PPA was present in 146 eyes (65%). Eyes with beta-zone PPA progressed more rapidly (-0.84+/-0.8 dB/year) than eyes without it (-0.51+/-0.6 dB/year; P<0.01). Multivariate regression showed significant influence of mean IOP (hazard ratio [HR], 1.11; P<0.01), IOP fluctuation (HR, 1.17; P = 0.02), and presence of beta-zone PPA (HR, 2.59; P<0.01) on VF progression. Moderate (0.5-1.5 dB/year; P = 0.01) and fast (>1.5 dB/year; P = 0.08) global rates of progression occurred more commonly in eyes with beta-zone PPA than in eyes without it. Thinner CCT (<525 microm) had a weak but significant correlation with presence of beta-zone PPA (kappa = 0.13). CONCLUSIONS Eyes with beta-zone PPA are at increased risk for glaucoma progression and warrant close clinical surveillance.

Corneal hysteresis and visual field asymmetry in open angle glaucoma.

PURPOSE To investigate the association between corneal biomechanical parameters and asymmetric primary open angle glaucoma (POAG) using the Ocular Response Analyzer (ORA). METHODS In a prospective cross-sectional study, ORA parameters were measured in 117 POAG patients with asymmetric visual fields (VF). The asymmetry in VF was defined as a five point difference between the eyes using the Advanced Glaucoma Intervention Study (AGIS) scoring system. Subjects with previous intraocular or refractive surgery, ocular comorbidities and diabetes were excluded. RESULTS In worse eyes, mean AGIS scores were significantly higher (8.1 ± 4.3 vs. 1.0 ± 1.6; P < 0.001) and mean corneal hysteresis (CH) was significantly lower (8.2 ± 1.9 vs. 8.9 ± 1.9 mm Hg; P < 0.001). Median ORA-corrected intraocular pressure was higher in the worse eyes (IOP(cc), 17.4 mm Hg vs. 16.9 mm Hg; P < 0.001). Worse eyes had a slightly lower mean corneal resistance factor (P = 0.04) and more myopic mean spherical equivalent (P = 0.02). No difference was seen in the central corneal thickness (CCT; P = 0.63) and Goldmann applanation tonometry (GAT; P = 0.32). On multivariate analysis, only CH retained an association with the worse eye (odds ratio, 25.9; 95% confidence interval, 10.1-66.5). ROC curves showed that only CH and IOP(cc) had a discriminative ability for the eye with worse VF (AUC, 0.82 and 0.70, respectively). CONCLUSIONS Asymmetric POAG was associated with asymmetry in ORA parameters but not in CCT and GAT. Lower CH was associated with worse eyes independently of its effect on IOP measurement and had the best discriminability for the eye with the worse VF.

The Region of Largest β-Zone Parapapillary Atrophy Area Predicts the Location of Most Rapid Visual Field Progression

PURPOSE To determine if visual field (VF) progression occurs most rapidly in the region of largest β-zone parapapillary atrophy (PPA). DESIGN Retrospective cohort. PARTICIPANTS One hundred twenty-five patients from the New York Glaucoma Progression Study with both β-zone PPA and VF progression. METHODS Treated open-angle glaucoma patients with 8 or more Swedish Interactive Threshold Algorithm Standard 24-2 VFs (Humphrey Field Analyzer II; Carl Zeiss Meditec, Inc., Dublin, CA) in either eye were identified. Eyes with optic disc photographs, β-zone PPA, less than 6 diopters myopia, and VF progression were studied. Visual field progression was defined using trend analysis as the presence of at least 2 adjacent progressing points in the same hemifield using standard pointwise linear regression (PLR) criteria. MAIN OUTCOME MEASURES The correlation between β-zone PPA and location of most rapid future VF progression. RESULTS One hundred twenty-five eyes (125 patients; mean age, 71.9 ± 12.3 years; 58% women; 75% European descent) with β-zone PPA and VF progression were enrolled. The mean follow-up was 6.8 ± 1.7 years and the mean number of VFs was 12.5 ± 3.6. Ninety-three patients (74%) had more β-zone PPA inferiorly and 32 patients (26%) had more β-zone PPA superiorly. The fastest VF progression occurred in the superior hemifield in 77 patients (62%) and in the inferior hemifield in 48 (38%) patients. Patients with superior VF progression had a superior localized mean rate of progression of -1.57 ± 1.7 dB/year, and patients with inferior VF progression had an inferior localized mean rate of -0.94 ± 1.4 dB/year (P = 0.012). The mean number of points reaching the predefined PLR end points was 5.6±7.5 for the superior VF hemifield and 3.0±4.9 for the inferior hemifield (P = 0.006). The hemifield with more points reaching PLR progression end points, with fastest average velocity of progression, or both was spatially consistent with the location of largest β-zone PPA in 89 (71%) patients (P = 0.0001, Fisher exact test; κ = 0.35; 95% confidence interval, 0.17-0.53). CONCLUSIONS In treated glaucoma patients with β-zone PPA and VF progression, the location of largest β-zone PPA typically correlates spatially with the region of the most rapid future VF progression. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Baseline mean deviation and rates of visual field change in treated glaucoma patients

PurposeTo evaluate the relationships between baseline visual field (VF) mean deviation (MD) and subsequent progression in treated glaucoma.MethodsRecords of patients seen in a glaucoma practice between 1999 and 2009 were reviewed. Patients with glaucomatous optic neuropathy, baseline VF damage, and ≥8 SITA-standard 24-2 VF were included. Patients were divided into tertiles based upon baseline MD. Automated pointwise linear regression determined global and localized rates (decibels (dB) per year) of change. Progression was defined when two or more adjacent test locations in the same hemifield showed a sensitivity decline at a rate of >1.0  dB per year, P<0.01.ResultsFor mild, moderate, and severe groups, progression was noted in 29.5, 31.2, and 26.0% of eyes (P=0.50) and global rates of VF change of progressing eyes were −1.3±1.2, −1.01±0.7, and −0.9±0.5 dB/year (P=0.09, analysis of variance). Within these groups, intraocular pressure (IOP) in stable vs progressing eyes were 15.5±3.3 vs 17.0±3.1 (P<0.01), 15.4±3.3 vs 15.9±2.5 (P=0.28), and 14.0±2.8 vs 14.8±2.3 mm Hg (P=0.07). More glaucoma filtering surgeries were performed in eyes with worse MD. There was no significant difference between groups regarding their risk of progression in both univariate (P=0.50) and multivariate (P=0.26) analyses adjusting for differences in follow-up IOP.ConclusionsAfter correcting for differences in IOP in treated glaucoma patients, we did not find a relationship between the rate of VF change (dB per year) and the severity of the baseline VF MD. This finding may have been due to more aggressive IOP lowering in eyes with more severe disease. Eyes with lower IOP progressed less frequently across the spectrum of VF loss.

Exfoliation syndrome in Nigeria.

Purpose: The purpose of this study was to estimate the prevalence of exfoliation syndrome (XFS) and its association with ocular disease in patients attending the eye clinic of the University College Hospital (UCH) in Ibadan, Nigeria. Materials and Methods: A total of 448 consecutive new patients, aged 30-90 years who presented to the eye clinic of UCH between December 2009 and November 2010 were evaluated. Each patient had a complete ophthalmic examination. Patients with exfoliative material on the anterior lens surface and/or pupillary margin in either or both eyes were considered to have XFS. Means, standard deviation, and 95% confidence intervals were calculated. Results: All the patients examined were from the southern part of Nigeria. Majority (94.2%) were of the Yoruba tribe from southwestern Nigeria, while 5.8% were from southeastern Nigeria. The mean age of the study cohort was 58.5 ± 13.8, 54.8% were males, 12 (2.7%) had XFS. All patients with XFS were of the Yoruba tribe, with a mean age 65.6 ± 5.6 years. There was a male predilection (66.7%). All eyes with XFS had lenticular opacities. XFS was bilateral in eight patients (66.7%) of whom seven patients (87.5%) had glaucoma and lenticular opacities bilaterally. Conclusion: This is the first report of the existence of XFS in Nigeria. Larger studies are necessary in this population to further investigate the disease.

Short-duration transient visual evoked potential for objective measurement of refractive errors

This study examined effects of uncorrected refractive errors (RE) in a short-duration transient visual evoked potential (SD t-VEP) system and investigated their role for objective measurement of RE. Refractive errors were induced by means of trial lenses in 35 emmetropic subjects. A synchronized single-channel EEG was recorded for emmetropia, and each simulated refractive state to generate 21 VEP responses for each subject. P100 amplitude (N75 trough to P100 peak) and latency were identified by an automated post-signal processing algorithm. Induced hypermetropia and myopia correlated strongly with both P100 amplitude and latency. To minimize the effect of baseline shift and waveform fluctuations, a VEP scoring system, based on software-derived P100 latency, amplitude and waveform quality, was used to estimate the RE. Using the VEP scores, a single VEP response had a high sensitivity and specificity for discerning emmetropia, small RE (<2 diopter) within a 2 diopter range and large RE (2–14 diopter) within a 4 diopter range. The VEP scoring system has a potential for objective screening of RE and for a more accurate 3-step objective refraction.

Corneal hysteresis and Beta-zone parapapillary atrophy.

PURPOSE To evaluate the relationship between β-zone parapapillary atrophy (βPPA) and corneal hysteresis (CH) in patients with glaucoma. DESIGN Prospective, cross-sectional study. METHODS Glaucoma patients aged 18 to 90 years with disc photographs within 12 months of the study visit were consecutively enrolled. Exclusion criteria included ocular surgery other than clear corneal phacoemulsification, myopia >6 diopters, contact lens use, and corneal abnormality. CH was measured using the Ocular Response Analyzer (ORA). Disc photographs were evaluated in a masked fashion for βPPA. RESULTS We enrolled 99 patients (mean age 67.6 years; 45 men, 54 women). Univariate analysis showed no significant difference in CH between eyes with and without βPPA (8.72 ± 0.23 vs 8.15 ± 0.27 mm Hg, P = .11). There were no differences in corneal resistance factor (CRF) (P = .47), central corneal thickness (CCT) (P = .11), ORA wave score (P = .23), age (P = .23), sex (P = .40), IOP (P = .86), or visual field mean deviation (VFMD) (P = .45). Eyes with βPPA were more myopic (-1.49 ± 0.27 vs -0.22 ± 0.31 diopters, P = .003). Multivariate analysis showed no significant difference in CH between eyes with and without βPPA (P = .38). Eyes with asymmetric βPPA also showed no significant difference in CH (8.97 ± 0.22 vs 9.10 ± 0.22 mm Hg, P = .69). CONCLUSIONS We found no significant differences in CH between eyes with and without βPPA or between fellow eyes with asymmetric βPPA.

Response to: “Morphologic and functional glaucomatous change after occurrence of single or recurrent optic disc haemorrhages”

Dear Editor:We read with interest the comments by Dr. Laemmer andcolleagues regarding our recent article “Recurrent optic dischemorrhage does not increase the rate of visual fieldprogression” [1]. It is gratifying to know that their studyconfirmed our results, and that they could not detect anydifference in the rate of visual field progression betweeneyes with a single detected disc hemorrhage and eyes withrecurrent disc hemorrhage.We would like to clarify several points raised byDr. Laemmer et al. There are significant differences inmethodologies between our two studies. We used atrend-based approach to investigate visual field pro-gression to provide an objective measure of thevelocity of progression, rather than the binary catego-rization into stable versus progressive eyes that isdetermined when using an event-based approach.Trend-analysis may be a more significant and usefultool for differentiating rapidly from slowly progressingeyes [2, 3], which may help tailor clinical managementmore objectively and, therefore, effectively.We look forward to learning more about their study afterpeerreviewandpublication.Thesamplesizedescribedintheirletter is relatively small (n=60) and may not have sufficientstatistical power to confirm or refute any differences betweengroups. Additional important missing information includesthe precise methodology for disc assessment and masking ofexaminers to disc and field results. The number of patientsremaining in each group at each year of follow-up willgreatly impact the survival curves and whether they are, infact, statistically different.