Shawn M. Iverson

Safety And Efficacy Of Achieving Single-Digit Intraocular Pressure Targets With Filtration Surgery In Eyes With Progressive Normal-Tension Glaucoma.

Purpose:Whereas achieving intraocular pressure (IOP) targets ⩽10 mm Hg typically requires surgical intervention, we sought to examine the safety and efficacy of trabeculectomy in normal-tension glaucoma (NTG). Methods:Patients with progressive NTG undergoing trabeculectomy with preoperative IOP⩽15 mm Hg during the 12-month period before surgery were identified at a single academic institution. Failure was defined as IOP reduction <20% below baseline (criteria A), <30% (criteria B), or <40% (criteria C), reoperation for glaucoma, or loss of light perception vision. Results:Thirty eyes of 28 patients (mean age, 73±8.7 y) were enrolled with a mean follow-up period of 50±31 months. Mean postoperative IOP (8.6±2.9 mm Hg) and medications (0.6±1.0) at final follow-up was significantly (P<0.001) reduced compared with before surgery (13.2±1.4 mm Hg and 2.5±1.2, respectively). The cumulative probability of failure during 5 years of follow-up was 32% (criteria A), 48%, (criteria B), and 67% (criteria C). The probability of successfully achieving an IOP goal ⩽10 mm Hg was 68% at 4 years of follow-up. Conclusions:Trabeculectomy is a safe and effective method for achieving single-digit IOP targets in NTG eyes with progression at low IOP.

Predicting Development of Glaucomatous Visual Field Conversion Using Baseline Fourier-Domain Optical Coherence Tomography

PURPOSE To predict the development of glaucomatous visual field (VF) defects using Fourier-domain optical coherence tomography (FD OCT) measurements at baseline visit. DESIGN Multicenter longitudinal observational study. Glaucoma suspects and preperimetric glaucoma participants in the Advanced Imaging for Glaucoma Study. METHODS The optic disc, peripapillary retinal nerve fiber layer (NFL), and macular ganglion cell complex (GCC) were imaged with FD OCT. VF was assessed every 6 months. Conversion to perimetric glaucoma was defined by VF pattern standard deviation (PSD) or glaucoma hemifield test (GHT) outside normal limits on 3 consecutive tests. Hazard ratios were calculated with the Cox proportional hazard model. Predictive accuracy was measured by the area under the receiver operating characteristic curve (AUC). RESULTS Of 513 eyes (309 participants), 55 eyes (46 participants) experienced VF conversion during 41 ± 23 months of follow-up. Significant (P < .05, Cox regression) FD OCT risk factors included all GCC, NFL, and disc variables, except for horizontal cup-to-disc ratio. GCC focal loss volume (FLV) was the best single predictor of conversion (AUC = 0.753, P < .001 for test against AUC = 0.5). Those with borderline or abnormal GCC-FLV had a 4-fold increase in conversion risk after 6 years (Kaplan-Meier). Optimal prediction of conversion was obtained using the glaucoma composite conversion index (GCCI) based on a multivariate Cox regression model that included GCC-FLV, inferior NFL quadrant thickness, age, and VF PSD. GCCI significantly improved predictive accuracy (AUC = 0.783) over any single variable (P = .04). CONCLUSIONS Reductions in NFL and GCC thickness can predict the development of glaucomatous VF loss in glaucoma suspects and preperimetric glaucoma patients.

Reproducibility of retinal oxygen saturation in normal and treated glaucomatous eyes

Aim To measure the reproducibility of retinal oxygen saturation (SaO2) levels among treated glaucomatous eyes and normal controls in a prospective non-randomised study. Methods Patients with perimetric glaucoma (PG) and normal controls were included. Exclusion criteria for both groups included visual acuity <20/30, unreliable visual fields, thyroidopathies, hemoglobinopathies, cardiovascular and pulmonary diseases. Retinal oximetry was performed twice consecutively on one randomly selected eye of PG and normal controls using spectrophotometric retinal oximeter (SRO; Oxymap ehf., Iceland). Four main retinal vessel pairs were analysed separately. Coefficients of variability (CoV), coefficients of repeatability (CoR) and intraclass correlation coefficients (ICCs) in arteries (a.SaO2) and veins (v.SaO2) were calculated. Results 23 PG (mean age 68.3±10.8 years) and 22 normal subjects (mean age 61.5±18.2 years; p=0.14) were included. The intraocular pressure and mean ocular perfusion pressure in glaucoma (14.4±4.2 mm Hg; 45.8±5.8 mm Hg) and controls (14.3±3.3 mm Hg; 45.8±6.1 mm Hg) were similar (p >0.05). In the PG group, the a.SaO2 had a CoV of 1.6%, a CoR of 4.7 and an ICC of 0.97; the v.SaO2 had a CoV of 5.9%, a CoR of 8.7 and an ICC of 0.96. In normals, the a.SaO2 had a CoV of 0.98%, a CoR of 3.3 and an ICC of 0.97; the v.SaO2 had a CoV of 4.8%, a CoR of 7.7 and an ICC of 0.93. Conclusions Retinal oximetry measurements using SRO are highly reproducible in both treated glaucomatous and normal eyes.

Effectiveness of Single-Digit IOP Targets on Decreasing Global and Localized Visual Field Progression After Filtration Surgery in Eyes With Progressive Normal-Tension Glaucoma.

Purpose:To examine the effectiveness of achieving single-digit intraocular pressure (IOP) targets with filtration surgery on decreasing global and localized visual field (VF) progression in eyes with progressive normal-tension glaucoma (NTG). Methods:A retrospective chart review was conducted to identify NTG patients who underwent trabeculectomy with mitomycin C between 2006 and 2010 for progressive VF loss with preoperative IOP⩽15 mm Hg during the 12 months before surgery. All eyes had glaucomatous optic neuropathy and progressive VF loss, uncontrolled IOP on maximum therapy, and a minimum of 2 baseline preoperative and 4 postoperative VF examinations. VF progression was assessed using Guided Progression Analysis (GPA) and Progressor software. Results:Fifteen eyes of 14 patients (mean age 71.8±7.5 y) were enrolled with mean follow-up of 71±26 months. Mean postoperative IOP (8.5±3.5 mm Hg) was significantly (P<0.001) reduced compared with preoperatively (13.1±1.5 mm Hg). The probability of achieving an IOP goal ⩽10 mm Hg was 66% at 4 years’ follow-up. The overall rate of postoperative VF progression using any method was 13.3% (1 eye using Progressor; 1 eye using GPA and Progressor). Average postoperative slope of MD (−0.25±0.86 dB/y) and pattern SD (0.49±0.83 dB/y) were improved (P=0.05 and 0.07) compared with the preoperative slopes (−1.05±0.66 and 1.21±0.71 dB/y). Conclusions:Achieving single-digit IOP targets with filtration surgery has a beneficial effect on reducing global and localized rates of VF progression in NTG eyes with progression at low IOP.

Comparison of primary graft survival following penetrating keratoplasty and Descemet's stripping endothelial keratoplasty in eyes with prior trabeculectomy

Purpose To compare corneal graft survival rate after primary Descemets stripping endothelial keratoplasty (DSEK) and primary penetrating keratoplasty (PK) in patients with prior trabeculectomy or medically managed glaucoma. Methods A retrospective chart review was conducted on consecutive patients who underwent DSEK or PK. Inclusion criteria consisted of eyes with a diagnosis of glaucoma prior to corneal transplantation and ≥6 months of follow-up. Graft failure was defined as an oedematous cornea with failure to maintain deturgescence lasting beyond a period of 1 month of intense steroid therapy or vascularisation and scarring resulting in irreversible loss of central graft clarity. Corneal graft survival was calculated using Kaplan–Meier survival analysis. Patients were divided into four groups: trabeculectomy-DSEK, trabeculectomy-PK, medical-DSEK or medical-PK. Results Fifty eyes (30 DSEK, 20 PK) of 50 patients (mean age 77±10 years) met the enrolment criteria. Mean follow-up was 17.4±14.2 months. A significantly higher proportion of the DSEK grafts (50%) compared with PK grafts (10%) failed at last follow-up (p=0.005). Kaplan–Meier analysis identified a significant difference between the groups with respect to time to graft failure (p=0.006). Patients with trabeculectomy who underwent DSEK had earlier graft failures than all other groups (p≤0.035), but there were no differences between the medical-DSEK, medical-PK and trabeculectomy-PK groups (all p>0.35). Conclusions Eyes with prior glaucoma showed higher rates of DSEK graft failure compared with PK. Patients with prior trabeculectomy demonstrated higher and earlier corneal graft failure rates with DSEK than with PK.

Detection of progressive macular thickness loss using optical coherence tomography in glaucoma suspect and glaucomatous eyes

AimsTo examine the rate of macular thickness loss using time-domain optical coherence tomography (OCT) in functionally progressing versus non-progressing eyes, determined by standard automated perimetry (SAP).MethodsGlaucoma suspects (GS) and glaucomatous (G) eyes underwent SAP and OCT imaging every 6 months. Functional progression was determined using pointwise linear regression, defined as 2 contiguous locations losing ≥1.0 dB/year at P<1.0% in the same hemifield. The annual rate of macular thickness loss was calculated from inner and outer regions of the macular map.Results72 eyes (43 GS and 29G) with ≥30 months of follow-up were enroled. Fourteen eyes demonstrated SAP progression. The annual rate of macular thickness loss (μm/year) in progressing eyes was faster (all P<0.05) than non-progressing eyes in temporal outer (−1.90±2.97 vs 0.33±2.77), nasal inner (−1.70±2.66 vs 0.14±2.76), superior inner (−2.15±4.57 vs 0.51±2.99), temporal inner quadrants (−2.58±5.05 vs −0.38±2.34), and the average of inner macular quadrants (−1.84±2.90 vs 0.03±2.10). The rate of loss in the nasal inner (P=0.02) and temporal outer (P=0.02) macular regions was associated with optic disc haemorrhage.ConclusionsEyes with SAP progression have significantly greater rates of macular thickness loss consistent with glaucomatous retinal ganglion cell atrophy, as compared with non-progressing eyes.

Frequency of abnormal retinal nerve fibre layer and ganglion cell layer SDOCT scans in healthy eyes and glaucoma suspects in a prospective longitudinal study

Background/aims To examine the frequency of abnormal retinal nerve fibre layer thickness (RNFLT) and ganglion cell complex (GCC) measurements among healthy and glaucoma suspect and preperimetric glaucoma (GSPPG) eyes in a prospective longitudinal study. Methods Normal and GSPPG eyes with ≥18 months follow-up were included. Spectral-domain optical coherence tomography (SDOCT) was performed annually in normal and biannually in GSPPG eyes. One eye was randomly selected for inclusion. RNFLT and GCC parameters with p>5% were classified as ‘within normal limits (WNL)’ and p<1% were classified as ‘outside normal limits (ONL)’. Results 23 normal and 74 GSPPG eyes were followed for a mean 43.4±9.6 months. During serial follow-up, 100% and 91% of normal eyes had all RNFLT and GCC parameters classified as WNL, respectively. 27 (37%) and 17 (23%) of GSPPG eyes had an ONL classification in at least one RNFLT and GCC parameter, respectively. A high percentage (41%–56%) of RNFLT and GCC measurements classified as ONL were not replicated on subsequent scans. The rates of loss for all parameters were similar (p>0.05) between the groups. Conclusions Specificity in this sample of healthy eyes was very high for RNFLT and GCC parameters. Confirmation of suspected SDOCT abnormalities is recommended to differentiate reproducible loss from long-term variability.

Glaucoma Diagnosis and Monitoring Using Advanced Imaging Technologies

Advanced ocular imaging technologies facilitate objective and reproducible quantification of change in glaucoma but at the same time, impose new challenges on scientists and clinicians for separating true structural change from imaging noise. This review examines time-domain and spectral-domain optical coherence tomography, confocal scanning laser ophthalmoscopy and scanning laser polarimetry technologies and discusses the diagnostic accuracy and the ability of each technique for evaluation of glaucomatous progression. A broad review of the current literature reveals that objective assessment of retinal nerve fiber layer, ganglion cell complex and optic nerve head topography may improve glaucoma monitoring when used as a complementary tool in conjunction with the clinical judgment of an expert.

The comparison of manual vs automated disc margin delineation using spectral-domain optical coherence tomography

AimsTo examine the impact of manual vs automated disc margin delineation on optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters using spectral-domain optical coherence tomography (SDOCT).MethodsA prospective cohort study consisting of normal, glaucoma suspect (GS) and glaucoma patients who underwent ONH and RNFL measurements using SDOCT technology (RTVue; Optovue Inc.). The retinal pigment epithelium/Bruch’s membrane (RPE/BM) complex end points were automatically determined first, and were manually redefined subsequently. Analysis of variance, coefficient of variation (COV), concordance correlation coefficient (CCC), and Bland–Altman plots were used for the analyses.ResultsNinety-nine eyes of 50 subjects (age 68±10 years) consisting of 36 glaucoma, 56 GS, and 7 normal eyes were included. The RNFL thickness measurements were similar (P>0.05) between the two methods of demarcation, except for the inferior-nasal sector (P=0.04). For the ONH measurements, the cup-to-disc (C/D) ratio and rim area showed significant differences between the two methods (P<0.001). COV/CCC values for the ONH parameters were as follows: cup area 17.6%/0.88; cup volume 7.4%/0.91; average C/D ratio 18.1%/0.78; rim area 25.3%/0.69; and rim volume 42.6%/0.71, respectively. CCC/COV values for the RNFL parameters were as follows: average 2.1%/0.98; inferior-temporal quadrant 8.1%/0.79; inferior-nasal quadrant INQ quadrant 12.6%/0.67; SNQ quadrant 7.8%/0.83; and STQ quadrant 7.8%/0.88, respectively.ConclusionAn overall high agreement and moderate–substantial concordance was observed between the demarcation methods. Automated disc margin delineation of SDOCT can be used reliably in clinical practice.

Surgical outcomes of superior versus inferior glaucoma drainage device implantation.

Purpose:To compare the safety and intraocular pressure (IOP) lowering efficacy of initial glaucoma drainage device (GDD) implantation performed at the superior versus inferior limbus. Methods:A retrospective chart review was conducted to identify patients with glaucoma who had undergone initial Baerveldt GDD surgery at the inferior limbus for uncontrolled IOP. All eyes of patients had a minimum of 6 months of postoperative follow-up. These eyes were frequency-matched to eyes with initial Baerveldt GDD implantation performed at the superior limbus, within 5 years of age and 6 months of follow-up. Baseline demographic and clinical information, as well as preoperative and postoperative IOP, visual acuity, and number of antiglaucoma medications were extracted. Failure was defined as IOP>21 mm Hg or not reduced by 20% below baseline on 2 consecutive follow-up visits after 3 months, IOP⩽5 mm Hg on 2 consecutive follow-up visits after 3 months, reoperation for glaucoma, or loss of light perception vision. Statistical methods consisted of Student t tests, &khgr;2 test, and Kaplan-Meier time to failure analysis. Results:Fifty eyes (17 inferior, 33 superior) of 43 patients were enrolled. Mean postoperative follow-up in both groups were similar (mean 26.2±15.2 mo for inferior and 23.9±10.43 mo for superior, P=0.54). Trabeculectomy had been performed previously in 8/17 (47%) and 11/33 (33%) eyes (P=0.34) with inferior and superior implants, respectively. Mean preoperative IOP (mm Hg) in the superior group (26±11) was significantly higher (P=0.02) when compared with the inferior group (21±7). Success rates were similar (P>0.05) between the inferior and superior GDD groups during the study period, with 64.7% and 75.8% classified as successful at 1-year of follow-up and 43.1% and 65.7% at 2 years of follow-up, respectively. There was no difference in cumulative proportions of eyes failing between the groups (P=0.20, log-rank test). The mean postoperative IOP and number of antiglaucoma medications were similar (all P>0.05) in both groups during the first 2 years of postoperative follow-up. The frequency and types of postoperative complications in both the groups were similar. The 36-month cumulative reoperation rates for IOP control were 33.8% and 9.1%, respectively, in the inferior and superior GDD groups (P=0.04 log-rank test). Conclusions:No differences were observed in the overall success rates of initial GDD implantation performed at the superior and inferior limbus in this cohort. However, inferior GDD implantation was associated with a greater incidence of reoperation for IOP control.