Repeatability of selective laser trabeculoplasty for open-angle glaucoma

Background

To analyze the results of repeat selective laser trabeculoplasty (SLT).

Methods

Inclusion criteria: participants with primary or secondary open-angle glaucoma (excluding uveitic) who had undergone SLT 360° (SLT 1) with diminution of response over time followed by repeat SLT 360° (SLT 2). Six months of follow-up were required and at least 6 months in between SLT 1 and 2. The main outcome measures were IOP reduction at 6 and 12 months and a comparison of the response between SLT 1 and 2.

Results

One hundred thirty-seven patients met the inclusion criteria. If only one eye had repeat treatment, that eye was chosen; if both eyes qualified, one was chosen at random. The baseline intraocular pressure (IOP) for SLT 1 = 20.3+/− 5.2 mmHg and SLT 2 = 19.4 +/− 5.0 was reduced to 16.4 +/− 3.9 and 16.7 +/− 4.7 at 1 year, respectively (p < .001). Medication use was not significantly changed, and was 2.2 +/− 1.2 at baseline for SLT 1 and 2.1 +/− 1.3 for SLT 2, and at 1 year was 1.9 +/− 1.3 and 2.2 +/− 1.2, respectively. A subanalysis of 62 patients matched for equivalent baselines showed a baseline IOP = 18.7 +/− 3.8 for SLT 1 and 18.7 +/− 3.5 for SLT 2, reduced to 16.0 +/− 4.3 and 15.3 +/− 3.8 at 1 year (p < .001).

Conclusion

Repeat SLT laser (360-degree treatment, followed by a loss of effect over time, then a second 360-degree treatment) in this population resulted in IOP lowering similar to that of the initial treatment.

Anterior Chamber Angle Morphometry Measurement Changes to Ambient Illumination Scaling in Visante Time Domain Optical Coherence Tomography

PURPOSE

To test the effect of ambient illumination scaling on the reproducibility and reliability anterior chamber metrics using the Visante time domain optical coherence tomography (TD-OCT) instrument.

MATERIALS AND METHODS

The inferior irido-corneal angles of 25 normal, healthy eyes were imaged twice with the Zeiss Visante TD-OCT under five strictly controlled ambient light conditions (foot candles (fc) measured with a light meter at camera/eye interface). Each eye was imaged 10 times totaling 250 assessments. Angle opening distance (AOD500/750), trabecular iris space area (TISA500/750), and scleral spur (SS) angle were graded twice by masked, trained graders at the Doheny Imaging Reading Center using the Visante's intrinsic tools. Lighting effects on measurements, intra-/inter-grader and acquisition analyses, and Bland-Altman plots were computed using Statistical Package for Social Science (SPSS Inc. version 18.0, Armonk, NY).

RESULTS

With a near linear relationship of angle metrics to lights levels (R² = 0.8-0.95), the analysis examines the differences from the brightest to darkest light levels. Decreasing ambient light levels from 1.0 to 0.0 fc decreased the average AOD500 measurement from 407 ± 136 µm to 315 ± 114 µm (mean percent difference (MPD) 29%, p < 0.001), AOD750 from 587 ± 184 µm to 496 ± 155 µm (MPD 18%, p < 0.001), TISA500 from 136 ± 43 µm² to 101 ± 37 µm² (MPD 35%, p < 0.001), TISA750 from 269 ± 81 µm² to 212 ± 68 µm² (MPD 27%, p < 0.001), and SS angle from 38.3% ± 9% to 32.1% ± 9% (MPD 19%, p < 0.001). Intra-/inter-grader results showed good reproducibility for each grader (MPD = 0.7-3%; coefficient of variation (CV) = 3.2-8.3%; R² = 0.8-0.95; p < 0.001 for all metrics) and between graders (MPD = 1.4-5.9%; CV = 6.7-14.2%; R² = 0.81-0.89; Pearson Correlation Coefficient (PCC) = 0.8-0.97 (p<0.001)). Bland-Altman plots did not demonstrate any apparent bias, with similar repeatability and agreement.

CONCLUSIONS

The results of this study show the high sensitivity of the anterior chamber to changes in the illumination. The slight decrease in light had a corresponding large decrease in Anterior Chamber Angle (ACA) metrics. With clinical diagnoses and treatments of eye diseases relying on these angle measurements, these findings emphasize the importance of strictly controlling light conditions in order to obtain reproducible measurements of anterior chamber geometry.

Longitudinal and Cross-Sectional Analyses of Age Effects on Retinal Nerve Fiber Layer and Ganglion Cell Complex Thickness by Fourier-Domain OCT

Purpose

We studied the effects of age and intraocular pressure (IOP) on retinal nerve fiber layer (NFL) and macular ganglion cell complex (GCC) thickness in normal eyes.

Methods

Data from subjects from the multicenter Advanced Imaging for Glaucoma Study (AIGS) were analyzed. The data included yearly visits from the normal subjects in the AIGS study. Fourier-domain optical coherence tomography (FD-OCT) was used to measure retinal NFL and macular GCC on each visit. Mixed effect models were used to evaluate the longitudinal effect of age and IOP on the NFL and GCC thickness. The measurements at baseline were used to examine the cross-sectional effects.

Results

The analysis included 192 eyes (92 participants) from AIGS between 2009 and 2013. The longitudinal analyses showed overall GCC thickness decreased 0.25 ± 0.05 μm per year (P < 0.001) while the overall NFL thickness decreased 0.14 ± 0.07 μm per year (P = 0.04). The cross-sectional analyses showed the GCC thickness was 0.17 ± 0.05 μm thinner per year of baseline age (P < 0.001), while the NFL was 0.21 ± 0.06 μm thinner (P < 0.001). There was no significant IOP effect on either GCC or NFL from either the longitudinal or cross-sectional analysis.

Conclusions

Longitudinal and cross-sectional analyses provided consistent rates of approximately 0.2% per year of age-related thinning in NFL and GCC thicknesses. This is relevant in establishing criteria to detect glaucoma-related thinning (disease progression) in excess of normal aging. IOP does not seem to be a significant confounder for progression analysis.

Translational Relevance

This study demonstrated the relevance of advanced imaging technology in diagnosing and monitoring glaucoma disease.

Combining measurements from three anatomical areas for glaucoma diagnosis using Fourier-domain optical coherence tomography

AIMS

To improve the diagnostic power for glaucoma by combining measurements of peripapillary nerve fibre layer (NFL), macular ganglion cell complex (GCC) and disc variables obtained with Fourier-domain optical coherence tomography (FD-OCT) into the glaucoma structural diagnostic index (GSDI).

METHODS

In this observational, cross-sectional study of subjects from the Advanced Imaging of Glaucoma Study, GCC and NFL of healthy and perimetrical glaucoma subjects from four major academic referral centres of the Advanced Imaging of Glaucoma Study were mapped with the RTVue FD-OCT. Global loss volume and focal loss volume parameters were defined using NFL and GCC normative reference maps. Optimal weights for NFL, GCC and disc variables were combined using multivariate logistic regression to build the GSDI. Glaucoma severity was classified using the Enhanced Glaucoma Staging System (GSS2). Diagnostic accuracy was assessed by sensitivity, specificity and the area under the receiver operator characteristic curve (AUC).

RESULTS

We analysed 118 normal eyes of 60 subjects, 236 matched eyes of 166 subjects with perimetrical glaucoma, and 105 eyes from a healthy reference group of 61 subjects. The GSDI included composite overall thickness and focal loss volume with weighted NFL and GCC components, as well as the vertical cup-to-disc ratio. The AUC of 0.922 from leave-one-out cross validation was better than the best component variable alone (p=0.047). The partial AUC in the high specificity region was also better (p=0.01), with a sensitivity of 69% at 99% specificity, and a sensitivity of 80.3% at 95% specificity. For GSS2 stages 3-5 the sensitivity was 98% at 99% specificity, and 100% at 95% specificity.

CONCLUSIONS

Combining structural measurements of GCC, NFL and disc variables from FD-OCT created a GSDI that improved the accuracy for glaucoma diagnosis.

TRIAL REGISTRATION NUMBER

NCT01314326.

Advanced imaging for glaucoma study: design, baseline characteristics, and inter-site comparison

PURPOSE

To report the baseline characteristics of the participants in the Advanced Imaging for Glaucoma Study. To compare the participating sites for variations among subjects and the performance of imaging instruments.

DESIGN

Multicenter longitudinal observational cohort study.

METHODS

A total of 788 participants (1329 eyes) were enrolled from 3 academic referral centers. There were 145 participants (289 eyes) in the normal group, 394 participants (663 eyes) in the glaucoma suspect/preperimetric glaucoma group, and 249 participants (377 eyes) in the perimetric glaucoma group. Participants underwent a full clinical examination, standard automated perimetry, and imaging with time-domain and Fourier-domain optical coherence tomography (OCT), scanning laser polarimetry, and confocal scanning laser ophthalmoscopy. The baseline average, population standard deviation, and repeatability of imaging-derived anatomic variables were reported for each technology and center.

RESULTS

Compared to the normal participants, glaucoma suspect/preperimetric glaucoma and perimetric glaucoma groups had significantly reduced anatomic measurements. Repeatability of nerve fiber layer thickness was best for Fourier-domain OCT (overall coefficient of variation <2%), followed by time-domain OCT (coefficient of variation 2%-2.9%), scanning laser polarimetry (coefficient of variation 2.6%-4.5%), and confocal scanning laser ophthalmoscopy rim area (coefficient of variation 4.2%-7.6%). A mixed-effects model showed that the differences between sites was less than 25 percent of the variation within groups and less than the differences between the normal and glaucoma suspect/preperimetric glaucoma group.

CONCLUSIONS

Site-to-site variation was smaller than both the variation within groups and the changes attributable to glaucoma. Therefore pooling of participants between sites is appropriate.

Refractory open-angle glaucoma after neodymium-yttrium-aluminum-garnet laser lysis of vitreous floaters

PURPOSE

To illustrate 3 cases of chronic open-angle glaucoma secondary to the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser vitreolysis procedure for symptomatic vitreous floaters.

DESIGN

Observational case series.

METHODS

Location of the study was the Doheny Eye Institute. Three eyes of 2 patients who developed chronic open-angle glaucoma after Nd:YAG vitreolysis for symptomatic floaters presenting with very high intraocular pressure (IOP >40 mm Hg) were selected. The time from the laser treatment to the onset of elevated pressure ranges from 1 week to 8 months. There was no associated inflammation, steroid use, or other identifiable cause of chronic IOP elevation.

RESULTS

All eyes were treated initially with glaucoma medication, followed by selective laser trabeculoplasty (SLT) and eventually glaucoma surgery (Trabectome) in 2 eyes for disease management. In all eyes, intraocular pressures were eventually stabilized within a normal pressure range from 18 to 38 months following Nd:YAG vitreolysis. At the latest follow-up post surgery, all eyes had intraocular pressures of 22 mm Hg or less with or without medications.

CONCLUSIONS

Secondary open-angle glaucoma is a complication of Nd:YAG vitreolysis for symptomatic floaters that may present with an increase in intraocular pressure immediately, or many months after the surgery. Furthermore this complication may be permanent and require chronic medical therapy or glaucoma surgery.

Retinal blood flow in glaucomatous eyes with single-hemifield damage

PURPOSE

To examine the hypotheses that in glaucomatous eyes with single-hemifield damage, retinal blood flow (RBF) is significantly reduced in the retinal hemisphere corresponding with the abnormal visual hemifield and that there are significant associations among reduced retinal sensitivity (RS) in the abnormal hemifield, RBF, and structural measurements in the corresponding hemisphere.

DESIGN

Prospective, nonrandomized, case-control study.

PARTICIPANTS

Thirty eyes of 30 patients with glaucoma with visual field loss confined to a single hemifield and 27 eyes of 27 controls.

METHODS

Normal and glaucomatous eyes underwent spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry. Doppler SD-OCT with a double-circle scanning pattern was used to measure RBF. The RBF was derived from the recorded Doppler frequency shift and the measured angle between the beam and the vessel. Total and hemispheric RBF, retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) values were calculated. The RS values were converted to 1/Lambert. Analysis of variance and regression analyses were performed.

MAIN OUTCOME MEASURES

Total and hemispheric RS, RBF, RNFL, and GCC values.

RESULTS

The total RBF (34.6±12.2 μl/minute) and venous cross-sectional area (0.039 ± 0.009 mm(2)) were reduced (P<0.001) in those with glaucoma compared with controls (46.5 ± 10.6 μl/minute; 0.052 ± 0.012 mm(2)). Mean RBF was reduced in the abnormal hemisphere compared with the opposite hemisphere (15.3 ± 5.4 vs. 19.3 ± 8.4 μl/minute; P = 0.004). The RNFL and GCC were thinner in the corresponding abnormal hemisphere compared with the opposite hemisphere (87.0 ± 20.2 vs. 103.7 ± 20.6 μm, P = 0.002; 77.6 ± 12.1 vs. 83.6 ± 10.1 μm, P = 0.04). The RBF was correlated with RNFL (r = 0.41; P = 0.02) and GCC (r = 0.43; P = 0.02) but not the RS (r = 0.31; P = 0.09) in the abnormal hemisphere. The RBF (19.3 ± 8.4 μl/minute), RNFL (103.7 ± 20.6 μm), and GCC (83.6 ± 10.1 μm) were reduced (P<0.05) in the hemisphere with apparently normal visual field in glaucomatous eyes compared with the mean hemispheric values of the normal eyes (23.2 ± 5.3 μl/minute, 124.8 ± 9.6 μm, and 96.1 ± 5.7 μm, respectively).

CONCLUSIONS

In glaucomatous eyes with single-hemifield damage, the RBF is significantly reduced in the hemisphere associated with the abnormal hemifield. Reduced RBF is associated with thinner RNFL and GCC in the corresponding abnormal hemisphere. Reduced RBF and RNFL and GCC loss also are observed in the perimetrically normal hemisphere of glaucomatous eyes.

Intracameral injection of tissue plasminogen activator to treat severe postoperative fibrinous reaction in iridocorneal endothelial syndrome

Iridocorneal endothelial (ICE) syndrome is a primary endothelial abnormality that can cause a spectrum of iris changes, corneal edema, and glaucoma. Glaucoma secondary to ICE is difficult to manage because of the inflammatory reaction and fibrosis it can cause. We present a case of postoperative fibrinous reaction following endoscopic cyclophotocoagulation in ICE that caused aqueous tube shunt occlusion and high intraocular pressure. The condition was successfully managed with tissue plasminogen activator.

Endoscopic ophthalmic surgery of the anterior segment

We summarize the uses of anterior segment endoscopic techniques and the basic science and technology of endoscopic cyclophotocoagulation (ECP) as compared with transscleral cyclophotocoagulation. This is followed by an analysis of patient selection for ECP, a description of surgical techniques, and clinical results. In addition, the ophthalmic endoscope has other uses in anterior segment surgeries. We discuss the techniques for these endoscope-assisted surgeries.

Regional correlation among ganglion cell complex, nerve fiber layer, and visual field loss in glaucoma

PURPOSE

To analyze the relationship among macular ganglion cell complex (GCC) thickness, peripapillary nerve fiber layer (NFL) thickness, and visual field (VF) defects in patients with glaucoma.

METHODS

A Fourier-domain optical coherence tomography (FD-OCT) system was used to map the macula and peripapillary regions of the retina in 56 eyes of 38 patients with perimetric glaucoma. The macular GCC and peripapillary NFL thicknesses were mapped and standard automated perimetry (SAP) was performed. Loss of GCC and NFL were correlated with the VF map on both a point-by-point and regional basis.

RESULTS

Correlation between GCC thickness and peripapillary NFL thickness produced a detailed correspondence map that demonstrates the arcuate course of the NFL in the macula. Corresponding regions within the GCC, NFL, and VF maps demonstrate significant correlation, once parafoveal retinal ganglion cell (RGC) displacement is taken into account.

CONCLUSIONS

There are significant point-specific and regional correlations between GCC loss, NFL loss, and deficits on SAP. Using these different data sources together may improve our understanding of glaucomatous damage and aid in the management of patients with glaucoma.

Benzalkonium chloride-induced denervation of orbicularis oculi muscle in rabbits

PURPOSE

To examine the potential for benzalkonium chloride (BAK) to cause denervation of the orbicularis oculi muscle (OOM) in a rabbit model.

METHODS

Pigmented rabbits were separated into five groups consisting of five rabbits each. Group 1 was injected with 1 mL of BAK 0.25% in the OOM of the upper eyelid. Group 2 was injected with 1 mL of BAK 0.5%. Group 3 included untreated controls. Groups 4 and 5 underwent surgical severing of the facial nerve (to cause complete paralysis of the OOM). Strength-duration curves for electrical stimulation of muscle twitches were measured for each group and chronaxie values were calculated to determine innervation status. Groups 1 and 4 were stimulated at 1 week postintervention while groups 2 and 5 were stimulated at 4 weeks postintervention. The rabbits were then sacrificed and the eyelids sent for histological analysis.

RESULTS

In group 1, all five rabbits demonstrated denervation of the OOM in the injected area. In group 2, one rabbit developed an abscess at the injection site and was sacrificed at 1 week. Of the remaining four rabbits, two showed complete denervation and two showed denervation with evidence of partial reinnervation. The histology demonstrated marked atrophy of the OOM for BAK-treated rabbits when compared with controls. In group 3, all five rabbits showed normal OOM function. In groups 4 and 5, all rabbits showed denervation of the OOM and histological evidence of muscle atrophy similar to groups 1 and 2.

CONCLUSIONS

BAK causes denervation when injected into the OOM in rabbits. The clinical relevance of this finding may be the onset of lagophthalmos and eyelid retraction in patients with chronic BAK exposure.

Retinal nerve fiber layer atrophy is associated with visual field loss over time in glaucoma suspect and glaucomatous eyes

PURPOSE

To compare prospectively detection of progressive retinal nerve fiber layer thickness (RNFL) atrophy identified using time-domain optical coherence tomography with visual field progression using standard automated perimetry in glaucoma suspect and preperimetric glaucoma patients or perimetric glaucoma patients.

DESIGN

Prospective, longitudinal clinical trial.

METHODS

Eligible eyes with 2 years or more of follow-up underwent time-domain optical coherence tomography and standard automated perimetry every 6 months. The occurrence of visual field progression was defined as the first follow-up visit reaching a significant (P < .05) negative visual field index slope over time. RNFL progression or improvement was defined as a significant negative or positive slope over time, respectively. Specificity was defined as the number of eyes with neither progression nor improvement, divided by the number of eyes without progression. Cox proportional hazard ratios were calculated using univariate and multivariate models with RNFL loss as a time-dependent covariate.

RESULTS

Three hundred ten glaucoma suspect and preperimetric glaucoma eyes and 177 perimetric glaucoma eyes were included. Eighty-nine eyes showed visual field progression and 101 eyes showed RNFL progression. The average time to detect visual field progression in those 89 eyes was 35 ± 13 months, and the average time to detect RNFL progression in those 101 eyes was 36 ± 13 months. In multivariate Cox models, average and superior RNFL losses were associated with subsequent visual field index loss in the entire cohort (every 10-μm loss; hazard ratio, 1.38; P = .03; hazard ratio, 1.20; P = .01; respectively). Among the entire cohort of 487 eyes, 42 had significant visual field index improvement and 55 had significant RNFL improvement (specificity, 91.4% and 88.7%, respectively).

CONCLUSIONS

Structural progression is associated with functional progression in glaucoma suspect and glaucomatous eyes. Average and superior RNFL thickness may predict subsequent standard automated perimetry loss.

Four-year incidence of open-angle glaucoma and ocular hypertension: the Los Angeles Latino Eye Study

PURPOSE

To estimate the 4-year incidence of open-angle glaucoma (OAG) and ocular hypertension (OHT) among adult Latinos 40 years of age and older.

DESIGN

Population-based longitudinal study.

METHODS

Comprehensive ophthalmologic examinations including intraocular pressure, visual field testing, and stereoscopic fundus photography were performed at both baseline and the 4-year follow-up examination. Incident OAG at the 4-year follow-up examination was defined as the presence of an open angle and a glaucomatous visual field abnormality or evidence of glaucomatous optic disc damage, or both when not present at baseline. Incident OHT was defined as intraocular pressure of more than 21 mm Hg and the absence of optic disc damage or abnormal visual field results at the 4 year follow-up examination when not present at baseline.

RESULTS

Among the 3939 participants (mean age, 54.7 ± 10.5 years) with complete data for a diagnosis of glaucoma at both baseline and follow-up examination, incident OAG at the 4-year follow-up was identified in 87 persons (4-year incidence rate, 2.3%; 95% confidence interval, 1.8% to 2.8%). Incident OHT at the 4-year follow-up was identified in 124 persons (4-year incidence rate, 3.5%; 95% confidence interval, 2.9% to 4.1%). In participants with OAG in 1 eye, the 4-year risk of OAG developing in the fellow eye was 5 times as high as the risk for those without OAG in either eye at baseline. In participants with OHT in 1 eye, the 4-year risk of OHT developing in the fellow eye was 10 times as high as the risk for those without OHT in either eye at baseline. The incidence rates of OAG and OHT were higher in older Latinos than in younger Latinos.

CONCLUSIONS

Incidence of OAG in Latinos is higher than in non-Hispanic whites, but lower than in Afro-Caribbeans. The relatively high rate of incident OAG and OHT underscores the need for community screening programs in this fastest growing segment of the United States population.

Baseline risk factors that predict the development of open-angle glaucoma in a population: the Los Angeles Latino Eye Study

OBJECTIVE

To determine which baseline sociodemographic, lifestyle, anthropometric, clinical, and ocular risk factors predict the development of open-angle glaucoma (OAG) in an adult population.

DESIGN

A population-based, prospective cohort study.

PARTICIPANTS

A total of 3772 self-identified Latinos aged ≥40 years from Los Angeles, California, who were free of OAG at baseline.

METHODS

Participants from the Los Angeles Latino Eye Study had standardized study visits at baseline and 4-year follow-up with structured interviews and a comprehensive ophthalmologic examination. We defined OAG as the presence of an open angle and a glaucomatous visual field abnormality and/or evidence of glaucomatous optic nerve damage in ≥1 eye. Multivariate logistic regression with stepwise selection was performed to determine which potential baseline risk factors independently predict the development of OAG.

MAIN OUTCOME MEASURES

Odds ratios for various risk factors.

RESULTS

Over the 4-year follow-up, 87 participants developed OAG. The baseline risk factors that predict the development of OAG include older age (odds ratio [OR] per decade, 2.19; 95% confidence interval [CI], 1.74-2.75; P<0.001), higher intraocular pressure (IOP; OR per mmHg, 1.18; 95% CI, 1.10-1.26; P<0.001), longer axial length (OR per mm, 1.48; 95% CI, 1.22-1.80; P<0.001), thinner central cornea (OR per 40 μm thinner, 1.30; 95% CI, 1.00-1.70; P = 0.050), higher waist-to-hip ratio (OR per 0.05 higher, 1.21; 95% CI, 1.05-1.39; P = 0.007) and lack of vision insurance (OR, 2.08; 95% CI, 1.26-3.41; P = 0.004).

CONCLUSIONS

Despite a mean baseline IOP of 14 mmHg in Latinos, higher IOP is an important risk factor for developing OAG. Biometric measures suggestive of less structural support such as longer axial length and thin central corneal thickness were identified as important risk factors. Lack of health insurance reduces access to eye care and increases the burden of OAG by reducing the likelihood of early detection and treatment of OAG.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Relationship among visual field, blood flow, and neural structure measurements in glaucoma

PURPOSE

To determine the relationship among visual field, neural structural, and blood flow measurements in glaucoma.

METHODS

Case-control study. Forty-seven eyes of 42 patients with perimetric glaucoma were age-matched with 27 normal eyes of 27 patients. All patients underwent Doppler Fourier-domain optical coherence tomography to measure retinal blood flow and standard glaucoma evaluation with visual field testing and quantitative structural imaging. Linear regression analysis was performed to analyze the relationship among visual field, blood flow, and structure, after all variables were converted to logarithmic decibel scale.

RESULTS

Retinal blood flow was reduced in glaucoma eyes compared to normal eyes (P < 0.001). Visual field loss was correlated with both reduced retinal blood flow and structural loss of rim area and retinal nerve fiber layer (RNFL). There was no correlation or paradoxical correlation between blood flow and structure. Multivariate regression analysis revealed that reduced blood flow and structural loss are independent predictors of visual field loss. Each dB decrease in blood flow was associated with at least 1.62 dB loss in mean deviation (P ≤ 0.001), whereas each dB decrease in rim area and RNFL was associated with 1.15 dB and 2.56 dB loss in mean deviation, respectively (P ≤ 0.03).

CONCLUSIONS

There is a close link between reduced retinal blood flow and visual field loss in glaucoma that is largely independent of structural loss. Further studies are needed to elucidate the causes of the vascular dysfunction and potential avenues for therapeutic intervention. Blood flow measurement may be useful as an independent assessment of glaucoma severity.

Ab interno Schlemm's canal surgery: trabectome and i-stent

In primary open-angle glaucoma, the site of greatest resistance to aqueous outflow is thought to be the trabecular meshwork. Augmentation of the conventional (trabecular) outflow pathway would facilitate physiologic outflow and subsequently lower intraocular pressure. Ab interno Schlemm's canal surgery including two novel surgical modalities, Trabectome (trabeculotomy internal approach) and Trabecular Micro-bypass Stent (iStent), is designed to reduce intraocular pressure by this approach. In contrast to external filtration surgeries such as trabeculectomy and aqueous tube shunt, these procedures are categorized as internal filtration surgeries and are both performed from an internal approach via gonioscopic guidance. Published results suggest that these surgical procedures are both safe and efficacious for the treatment of open-angle glaucoma.

Vision loss and recovery after trabeculectomy: risk and associated risk factors

OBJECTIVES

To assess the risk of long-term vision loss after trabeculectomy and to determine the course of long-term vision loss vs transient loss and recovery.

METHODS

The medical records of 301 eyes in 262 patients undergoing trabeculectomy between January 1999 and September 2003 were retrospectively reviewed. Postoperative vision loss was categorized as mild or moderate (decrease in Snellen visual acuity of 3-5 lines) vs severe (decrease of >5 lines). Postoperative vision loss was considered permanent if visual acuity did not have a return of 3 lines within a 6-month follow-up period.

RESULTS

Permanent vision loss occurred in 24 of 301 eyes (8.0%): 13 (4.3%) had mild or moderate vision loss, and 11 (3.7%) had severe vision loss. Ten eyes (3.3%) with permanent mild or moderate vision loss and 6 eyes (2.0%) with permanent severe vision loss had no identifiable cause. Significant risk factors for permanent severe unexplained vision loss were preoperative split fixation on visual fields, preoperative number of quadrants with split fixation, and postoperative choroidal effusions with eventual resolution. Transient vision loss occurred in 170 of 301 eyes (56.5%): 79 (26.2%) had mild or moderate vision loss, with a mean time to recovery of 88 days (range, 6-720 days), and 91 (30.2%) had severe vision loss, with a mean time to recovery of 78 days (range, 6-720 days).

CONCLUSIONS

Transient vision loss after trabeculectomy is common and may take up to 2 years for recovery. The risk of permanent vision loss is less common but significant. Two percent of our study population experienced permanent severe unexplained vision loss ("snuff-out"), and risk factors included preoperative split fixation on visual fields, preoperative number of quadrants with split fixation, and postoperative choroidal effusions with eventual resolution.