Outcomes of microPulse transscleral laser therapy in eyes with prior glaucoma aqueous tube shunt

PURPOSE

To evaluate the outcomes of micropulse transscleral laser therapy (MP-TLT) in patients with uncontrolled glaucoma and prior glaucoma aqueous tube shunt.

METHODS

In this single‑center, retrospective, interventional case series, eyes that underwent MP-TLT and had prior glaucoma aqueous tube shunt surgeries were included. The Cyclo Glaucoma Laser System (IRIDEX Corporation, Mountain View, CA, USA) with the MicroPulse P3 probe (version 1) was used. Post‑operative data were collected at day 1, week 1, and months 1, 3, 6, 12, 18, 24, 30 and 36.

RESULTS

A total of 84 eyes (84 patients) with mean age of 65.8 ± 15.2 years and with advanced glaucoma (baseline mean deviation -16.25 ± 6.80 dB and best-corrected visual acuity 0.82 ± 0.83 logMar) were included in the study. Baseline mean IOP was 19.95 ± 5.6 mm Hg with a mean number of medications 3.39 ± 1.02. There were statistically significant differences in IOP between baseline and all follow-up visits (p < 0.01 for all). The mean percentage of IOP reduction between baseline and different follow-up visits ranged from 23.4% to 35.5% (p < 0.01). There was a significant reduction of visual acuity (≥ 2-lines) at 1 year (30.3%) and 2 years (76.78%). There was a statistically significant reduction in the number of glaucoma medications between baseline and all follow-up visits after postoperative week 1 (p < 0.05 for all). No severe complications including persistent hypotony and related complications were observed. At the last follow-up visit, only 24 (28%) eyes out of 84 eyes remained in the study.

CONCLUSION

MP-TLT is an effective treatment for reducing IOP and decreasing the number of medications in patients with advanced glaucoma and prior glaucoma aqueous tube shunt.

Evidence-Based Consensus Guidelines Series for MicroPulse Transscleral Laser Therapy - Surgical Technique, Post-Operative Care, Expected Outcomes and Retreatment/Enhancements

Purpose

To provide expert consensus and evidence-based current guidelines on treatment technique, postoperative care, expected outcomes and retreatment for MicroPulse Transscleral Laser Treatment (TLT).

Methods

A comprehensive search of PubMed led to the identification and analysis of 61 studies on MicroPulse TLT. To provide guidance in areas where there was not enough available literature, a three-round Delphi method was conducted involving 10 international experts in MicroPulse TLT.

Results

The response rate was 70% in the first round, 70% in the second round, and 80% in the third round of the Delphi method. Once all responses were aggregated, a live meeting was held with 90% attendance, and consensus was achieved on each of the findings detailed in this manuscript.

Conclusion

Used within appropriate treatment parameters, with proper technique and patient selection, MicroPulse TLT is a safe and effective treatment for many types and severities of glaucoma. MicroPulse TLT represents a useful addition to the glaucoma armamentarium.

Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Does the ISNT rule apply to the radial peripapillary capillary vessel density in OCT angiography?

PURPOSE

To investigate the applicability of ISNT (inferior ≥ superior ≥ nasal ≥ temporal), IST (inferior ≥ superior ≥ temporal), and T min (temporal quadrant with the minimum value) rules to the peripapillary nerve fiber layer (NFL) thickness and radial peripapillary capillary (RPC) vessel density (VD) using Optical Coherence Tomography (OCT) and OCT angiography (OCT-A).

MATERIALS AND METHODS

This cross-sectional study included 134 eyes of 74 healthy individuals. NFL thickness and RPC VD were measured in all four quadrants using OCT and OCT-A in order to determine the number of eyes that obey the ISNT, IST, and T min rules.

RESULTS

Mean age was 48.8 ± 15.5 (range 25-82) years. The ISNT rule was valid in 52 eyes (38.81%) on OCT and only 12 eyes (8.95%) on OCT-A scans. The IST rule was followed by 83 (61.94%) and 37 (27.61%) eyes on OCT and OCT-A scans respectively. The T min rule was valid in 86 eyes (64.18%) in OCT scans and in 26 eyes (19.4%) in OCT-A scans.

CONCLUSION

The topography of the RPC network does not obey the ISNT rule in healthy eyes. The ISNT rule and its variants were found to be more relevant in OCT NFL thickness measurements compared to OCT-A RPC VD measurements.

Segmental differences found in aqueous angiographic-determined high - and low-flow regions of human trabecular meshwork

This work sought to compare aqueous angiographic segmental patterns with bead-based methods which directly visualize segmental trabecular meshwork (TM) tracer trapping. Additionally, segmental protein expression differences between aqueous angiographic-derived low- and high-outflow human TM regions were evaluated. Post-mortem human eyes (One Legacy and San Diego eye banks; n = 15) were perfused with fluorescent tracers (fluorescein [2.5%], indocyanine green [0.4%], and/or fluorescent microspheres). After angiographic imaging (Spectralis HRA+OCT; Heidelberg Engineering), peri-limbal low- and high-angiographic flow regions were marked. Aqueous angiographic segmental outflow patterns were similar to fluorescent microsphere TM trapping segmental patterns. TM was dissected from low- and high-flow areas and processed for immunofluorescence or Western blot and compared. Versican expression was relatively elevated in low-flow regions while MMP3 and collagen VI were relatively elevated in high-flow regions. TGF-β2, thrombospondin-1, TGF-β receptor1, and TGF-β downstream proteins such as α-smooth muscle actin were relatively elevated in low-flow regions. Additionally, fibronectin (FN) levels were unchanged, but the EDA isoform (FN-EDA) that is associated with fibrosis was relatively elevated in low-flow regions. These results show that segmental aqueous angiographic patterns are reflective of underlying TM molecular characteristics and demonstrate increased pro-fibrotic activation in low-flow regions. Thus, we provide evidence that aqueous angiography outflow visualization, the only tracer outflow imaging method available to clinicians, is in part representative of TM biology.

Clinical results of ab interno trabeculotomy using the trabectome in patients with uveitic glaucoma

IMPORTANCE

To evaluate the safety and efficacy of ab interno trabeculotomy (AIT) (trabecular ablation) with the trabectome in patients with uveitic glaucoma.

BACKGROUND

Traditional glaucoma filtration surgeries in the uveitic patient population come with a higher risk of complications such as failure and hypotony.

DESIGN

Retrospective observational cohort study.

PARTICIPANTS

All patients diagnosed with uveitic glaucoma were included in this study. Patients were excluded if they have less than 12 months of follow-up.

METHODS

All patients who received AIT alone or combined with phacoemulsification.

MAIN OUTCOME MEASURES

Major outcomes include intraocular pressure (IOP), number of glaucoma medications and secondary glaucoma surgery, if any. Kaplan-Meier method was used for survival analysis and success was defined as IOP ≤21 mmHg, at least 20% IOP reduction from baseline for any two consecutive visits after 3 months, no additional glaucoma medications, and no secondary glaucoma surgery.

RESULTS

A total of 45 eyes, 45 patients, with an average age of 52 years were included in the study. The majority were Japanese (40%) and underwent AIT alone (71%). IOP was reduced from 29.2 ± 8.0 to 16.7 ± 4.6 mmHg at 12 months (P < .01*), while the number of glaucoma medications was reduced from 4.0 ± 1.0 to 2.5 ± 1.6 (P < .01*). Survival rate at 12 months was 91%. Six cases required secondary glaucoma surgery and no other serious complication were reported.

CONCLUSIONS AND RELEVANCE

The trabectome AIT procedure appears to be effective in reducing IOP in uveitic glaucoma patients. Although no statistically significant difference was found in the number of glaucoma medications, a decreasing trend was found.

Predictive Factors for the Rate of Visual Field Progression in the Advanced Imaging for Glaucoma Study

PURPOSE

To investigate predictive factors associated with the rate of visual field (VF) loss in open-angle glaucoma.

DESIGN

Prospective multicenter cohort study.

METHODS

Perimetric glaucoma patients of the Advanced Imaging for Glaucoma study were selected for analysis if they had 9 completed visits. Confirmed rapid significant progression (CRSP) of VF was defined as a significant (P < 0.05) negative VF index (VFI) slope of -1%/year or a mean deviation slope of -0.5 dB/year, confirmed at 2 consecutive follow-up visits. Slow progression was defined as VFI slope greater than -0.5%/year or a mean deviation slope of -0.25 dB/year. Fourier-domain optical coherence tomography (FD-OCT) measured optic disc, peripapillary retinal nerve fiber layer (NFL), and macular ganglion cell complex (GCC) thicknesses. Logistic regression was used to identify baseline predictors for CRSP and slow progression. Linear regression was used to identify baseline predictors for the VFI and mean deviation slope.

RESULTS

Eyes (n = 150) of 103 participants were included. Slow progression was observed in 80 eyes (53.3%) and CRSP in 23 eyes (15.3%). Larger NFL and GCC baseline focal loss volume (FLV), thinner central corneal thickness, and lower VFI were significant (P < 0.05) baseline predictors of more rapid progression on univariate analysis. The predictor with the highest odds ratio (OR) was NFL-FLV, which was also the most significant non-VF predictor in the multivariate analysis. Eyes with NFL-FLV >8.5% had an OR of 2.67 for CRSP and 0.42 for slow progression. Disc hemorrhage during the follow-up was also important, with an OR of 2.61 for CRSP and 0.23 for slow progression for each occurrence.

CONCLUSIONS

Focal loss measured by FD-OCT or VF along with CCT are strong baseline predictors for the rate of glaucoma progression.

Endoscopic Cyclophotocoagulation and Other Cyclodestructive Methods: Histopathologic Comparison of In Vivo Treatment in Humans and Monkeys

PURPOSE

To compare the histologic effects of endoscopic cyclophotocoagulation (ECP) with other ciliary body ablative procedures. A secondary aim was to correlate these findings with historical clinical success and complication rates.

DESIGN

Prospective, qualitative comparison of histopathologic tissue analysis.

PARTICIPANTS

Two eyes of two patients who had undergone ECP for open-angle glaucoma were studied. Two eyes from a healthy monkey were treated with ECP and studied. For comparison, 1 eye each of patients who had undergone contact and noncontact neodymium:yttrium-aluminum-garnet transscleral cyclophotocoagulation (TCP) for open-angle glaucoma were analyzed.

METHODS

The human globes were enucleated and submitted for analysis by gross examination and light and electron microscopy. Monkey eyes were studied by gross examination and light microscopy 1 week, 2 weeks, and 1 month after ECP.

MAIN OUTCOME MEASURES

Gross and histopathologic specimens of all eyes were analyzed with respect to location and type of tissue effects and degree of collateral damage.

RESULTS

The gross analysis of all ECP specimens showed a uniform anterior-to-posterior whitening of each treated ciliary process. This correlated with microscopic evidence of loss of pigmentation from the pigmented ciliary epithelial cells seen with mostly preserved architecture and vasculature of the ciliary processes. By comparison, the TCP specimens showed erratic treatment of the ciliary processes with overlap into the pars plicata of the ciliary body. Microscopic analysis revealed significant disruption of the cells throughout the ciliary processes and loss of vessels within the stroma.

CONCLUSIONS

Treatment with ECP results in less overall tissue destruction and a targeted effect on the pigmented ciliary epithelium of the ciliary processes when compared with TCP.

Comparison of Glaucoma Progression Detection by Optical Coherence Tomography and Visual Field

PURPOSE

To compare longitudinal glaucoma progression detection using optical coherence tomography (OCT) and visual field (VF).

DESIGN

Validity assessment.

METHODS

We analyzed subjects with more than 4 semi-annual follow-up visits (every 6 months) in the multicenter Advanced Imaging for Glaucoma Study. Fourier-domain optical coherence tomography (OCT) was used to map the thickness of the peripapillary retinal nerve fiber layer (NFL) and ganglion cell complex (GCC). OCT-based progression detection was defined as a significant negative trend for either NFL or GCC. VF progression was reached if either the event or trend analysis reached significance.

RESULTS

The analysis included 356 glaucoma suspect/preperimetric glaucoma (GS/PPG) eyes and 153 perimetric glaucoma (PG) eyes. Follow-up length was 54.1 ± 16.2 months for GS/PPG eyes and 56.7 ± 16.0 for PG eyes. Progression was detected in 62.1% of PG eyes and 59.8% of GS/PPG eyes by OCT, significantly (P < .001) more than the detection rate of 41.8% and 27.3% by VF. In severity-stratified analysis of PG eyes, OCT had significantly higher detection rate than VF in mild PG (63.1% vs. 38.7%, P < .001), but not in moderate and advanced PG. The rate of NFL thinning slowed dramatically in advanced PG, but GCC thinning rate remained relatively steady and allowed good progression detection even in advanced disease. The Kaplan-Meier time-to-event analyses showed that OCT detected progression earlier than VF in both PG and GS/PPG groups.

CONCLUSIONS

OCT is more sensitive than VF for the detection of progression in early glaucoma. While the utility of NFL declines in advanced glaucoma, GCC remains a sensitive progression detector from early to advanced stages.

Structural and functional imaging of aqueous humour outflow: a review

Maintaining healthy aqueous humour outflow (AHO) is important for intraocular cellular health and stable vision. Impairment of AHO can lead to increased intraocular pressure, optic nerve damage and concomitant glaucoma. An improved understanding of AHO will lead to improved glaucoma surgeries that enhance native AHO as well as facilitate the development of AHO-targeted pharmaceuticals. Recent AHO imaging has evolved to live human assessment and has focused on the structural evaluation of AHO pathways and the functional documentation of fluid flow. Structural AHO evaluation is predominantly driven by optical coherence tomography, and functional evaluation of flow is performed using various methods, including aqueous angiography. Advances in structural and functional evaluation of AHO are reviewed with discussion of strengths, weaknesses and potential future directions.

Swept-source OCT angiography imaging of the macular capillary network in glaucoma

PURPOSE

To evaluate the macular capillary network density of superficial and deep retinal layers (SRL/DRL) by swept-source optical coherence tomography angiography (OCTA) in patients with primary open angle glaucoma (POAG) and to compare the results with those of normal subjects.

METHOD

In this prospective study, 24 eyes of 24 normal individuals and 24 eyes of 24 patients with mild to moderate POAG underwent fovea centred 6×6 mm cube macular OCTA imaging by a swept-source OCTA device (Triton, Topcon, Tokyo, Japan). Quantitative analysis of the retinal vasculature was performed by assessing vessel density (VD) as the ratio of the retinal area occupied by vessels at the SRL and DRL.

RESULTS

The mean VD (ratio) at the SRL and DRL was statistically significantly lower in patients with POAG (SRL, p<0.001; DRL, p<0.001). In the SRL, the mean±SD VD ratio was 0.34±0.05 in patients with POAG and 0.40±0.02 in normal individuals (p<0.001). In the DRL, the mean (SD) ratio was 0.37±0.05 in patients with POAG and 0.43±0.02 in normal individuals (p<0.001). The mean VD at the SRL was significantly correlated with ganglion cell inner plexiform layer thickness (r=0.42, p=0.04) but not with visual field mean deviation (r=0.4, p=0.06) and retinal nerve fibre layer thickness (r=0.5, p=0.06). The mean VD at the DRL did not show significant correlation with any other glaucoma parameter (p>0.05).

CONCLUSION

The assessment of macular VD by swept-source OCTA may offer additional information for detection of glaucoma.

Aqueous Angiography-Mediated Guidance of Trabecular Bypass Improves Angiographic Outflow in Human Enucleated Eyes

Purpose

To assess the ability of trabecular micro-bypass stents to improve aqueous humor outflow (AHO) in regions initially devoid of AHO as assessed by aqueous angiography.

Methods

Enucleated human eyes (14 total from 7 males and 3 females [ages 52–84]) were obtained from an eye bank within 48 hours of death. Eyes were oriented by inferior oblique insertion, and aqueous angiography was performed with indocyanine green (ICG; 0.4%) or fluorescein (2.5%) at 10 mm Hg. With an angiographer, infrared and fluorescent images were acquired. Concurrent anterior segment optical coherence tomography (OCT) was performed, and fixable fluorescent dextrans were introduced into the eye for histologic analysis of angiographically positive and negative areas. Experimentally, some eyes (n = 11) first received ICG aqueous angiography to determine angiographic patterns. These eyes then underwent trabecular micro-bypass sham or stent placement in regions initially devoid of angiographic signal. This was followed by fluorescein aqueous angiography to query the effects.

Results

Aqueous angiography in human eyes yielded high-quality images with segmental patterns. Distally, angiographically positive but not negative areas demonstrated intrascleral lumens on OCT images. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Trabecular bypass but not sham in regions initially devoid of ICG aqueous angiography led to increased aqueous angiography as assessed by fluorescein (P = 0.043).

Conclusions

Using sequential aqueous angiography in an enucleated human eye model system, regions initially without angiographic flow or signal could be recruited for AHO using a trabecular bypass stent.

Effects of diurnal, lighting, and angle-of-incidence variation on anterior segment optical coherence tomography (AS-OCT) angle metrics

BACKGROUND

First reported study to assess the effect of diurnal variation on anterior chamber angle measurements, as well as, to re-test the effects of lighting and angle-of-incidence variation on anterior chamber angle (ACA) measurements acquired by time-domain anterior segment optical coherence tomography (AS-OCT).

METHODS

A total of 30 eyes from 15 healthy, normal subjects underwent anterior chamber imaging using a Visante time-domain AS-OCT according to an IRB-approved protocol. For each eye, the inferior angle was imaged twice in the morning (8 am - 10 am) and then again in the afternoon (3 pm - 5 pm), under light meter-controlled conditions with ambient room lighting 'ON' and lights 'OFF', and at 5° angle of incidence increments. The ACA metrics measured for each eye were: angle opening distance (AOD, measured 500 and 750 μm anterior from scleral spur), the trabecular-iris-space area (TISA, measured 500 and 750 μm anterior from scleral spur), and scleral spur angle. Measurements were performed by masked, certified Reading Center graders using the Visante's Internal Measurement Tool. Differences in measurements between morning and afternoon, lighting variations, and angle of incidence were compared.

RESULTS

Mean age of the participants was 31.2 years (range 23-58). Anterior chamber angle metrics did not differ significantly from morning to afternoon imaging, or when the angle of incidence was offset by 5° in either direction away from the inferior angle 6 o'clock position. (p-value 0.13-0.93). Angle metrics at the inferior corneal limbus, 6 o'clock position (IC270), with room lighting 'OFF', showed a significant decrease (p < 0.05) compared to room lighting 'ON'.

CONCLUSIONS

There does not appear to be significant diurnal variation in AS-OCT parameters in normal individuals, but lighting conditions need to be strictly controlled since variation in lighting led to significant variability in AS-OCT parameters. No changes in ACA parameters were noted by varying the angle-of-incidence, which gives confidence in being able to perform longitudinal studies in approximately the same area (plus/minus 5° of original scan location).

Retinal vessel density from optical coherence tomography angiography to differentiate early glaucoma, pre-perimetric glaucoma and normal eyes

Purpose

To evaluate optic nerve vascular density using swept source optical coherence tomography angiography (OCTA) in patients with early primary open angle glaucoma (POAG), pre-perimetric glaucoma and normal eyes.

Methods

This is a prospective, observational study including 56 eyes in total and divided into 3 groups; 20 eyes with mild POAG, 20 pre-perimetric glaucoma eyes, and 16 age-matched normal eyes as controls. The optic disc region was imaged by a 1050-nm-wavelength swept-source OCT system (DRI OCT Triton, TOPCON). Vessel density was assessed as the ratio of the area occupied by the vessels in 3 distinct regions: 1) within the optic nerve head; 2) in the 3 mm papillary region around the optic disc; and 3) in the peripapillary region, defined as a 700-μm-wide elliptical annulus around the disc. The potential associations between vessel density and structural, functional measures were analyzed.

Results

There was a statistically significant difference for the peripapillary vessel density, optic nerve head vessel density, and papillary vessel density among all the groups (p<0.001). Control eyes showed a significant difference for all measured vessel densities compared to glaucomatous eyes (p values from 0.001 to 0.024). There was a statistically significant difference between control and pre-perimetric glaucoma eyes for peripapillary, optic nerve head and papillary vessel density values (p values from 0.001 to 0.007). The optic nerve head vessel density, superior and inferior papillary area vessel density (Pearson r = 0.512, 0.436, 0.523 respectively) were highly correlated with mean overall, superior and inferior RNFL thickness in POAG eyes (p = 0.04, p = 0.02 and p = 0.04 respectively). Multiple linear regression analysis of POAG group showed that optic nerve head vessel density in POAG group was more strongly linked to RNFL thickness than to any other variables.

Conclusions

Eyes with mild POAG could be differentiated from pre-perimetric glaucoma eyes, which also could be differentiated from normal eyes using OCTA-derived retinal vessel density measurements.

Baseline Fourier-Domain Optical Coherence Tomography Structural Risk Factors for Visual Field Progression in the Advanced Imaging for Glaucoma Study

PURPOSE

To identify baseline structural parameters that predict the progression of visual field (VF) loss in patients with open-angle glaucoma.

DESIGN

Multicenter cohort study.

METHODS

Participants from the Advanced Imaging for Glaucoma (AIG) study were enrolled and followed up. VF progression is defined as either a confirmed progression event on Humphrey Progression Analysis or a significant (P < .05) negative slope for VF index (VFI). Fourier-domain optical coherence tomography (FDOCT) was used to measure optic disc, peripapillary retinal nerve fiber layer (NFL), and macular ganglion cell complex (GCC) thickness parameters.

RESULTS

A total of 277 eyes of 188 participants were followed up for 3.7 ± 2.1 years. VF progression was observed in 83 eyes (30%). Several baseline NFL and GCC parameters, but not disc parameters, were found to be significant predictors of progression on univariate Cox regression analysis. The most accurate single predictors were the GCC focal loss volume (FLV), followed closely by NFL-FLV. An abnormal GCC-FLV at baseline increased risk of progression by a hazard ratio of 3.1. Multivariate Cox analysis showed that combining age and central corneal thickness with GCC-FLV in a composite index called "Glaucoma Composite Progression Index" (GCPI) further improved the accuracy of progression prediction. GCC-FLV and GCPI were both found to be significantly correlated with the annual rate of change in VFI.

CONCLUSION

Focal GCC and NFL loss as measured by FDOCT are the strongest predictors for VF progression among the measurements considered. Older age and thinner central corneal thickness can enhance the predictive power using the composite risk model.

Aqueous Angiography with Fluorescein and Indocyanine Green in Bovine Eyes

Purpose

We characterize aqueous angiography as a real-time aqueous humor outflow imaging (AHO) modality in cow eyes with two tracers of different molecular characteristics.

Methods

Cow enucleated eyes (n = 31) were obtained and perfused with balanced salt solution via a Lewicky AC maintainer through a 1-mm side-port. Fluorescein (2.5%) or indocyanine green (ICG; 0.4%) were introduced intracamerally at 10 mm Hg individually or sequentially. With an angiographer, infrared and fluorescent images were acquired. Concurrent anterior segment optical coherence tomography (OCT) was performed, and fixable fluorescent dextrans were introduced into the eye for histologic analysis of angiographically positive and negative areas.

Results

Aqueous angiography in cow eyes with fluorescein and ICG yielded high-quality images with segmental patterns. Over time, ICG maintained a better intraluminal presence. Angiographically positive, but not negative, areas demonstrated intrascleral lumens with anterior segment OCT. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Sequential aqueous angiography with ICG followed by fluorescein in cow eyes demonstrated similar patterns.

Conclusions

Aqueous angiography in model cow eyes demonstrated segmental angiographic outflow patterns with either fluorescein or ICG as a tracer.

Translational Relevance

Further characterization of segmental AHO with aqueous angiography may allow for intelligent placement of trabecular bypass minimally invasive glaucoma surgeries for improved surgical results.

Utility of anterior segment swept-source optical coherence tomography for imaging eyes with antecedent ocular trauma

PURPOSE

To evaluate the utility of swept source optical coherence tomography (SS-OCT) for the analysis of anterior segment structures in cases with previous traumatic eye injuries.

OBSERVATIONS

We report three eyes of three patients with anterior segment traumatic eye injury and highlight the role of SS-OCT in their evaluation and management. This technology enabled us to visualize the structural details of anterior segment of the eye and augment the clinical examination in our patients. Given that it is non-invasive and that there is no contact involved, it may be an ideal imaging modality for traumatic eye injuries for viewing the details before and after any clinical intervention especially in the sub-acute setting.

CONCLUSIONS

The anterior segment SS-OCT is a useful device allowing non-invasive, non-contact, real-time, cross-sectional anterior segment images of eyes with previous ocular trauma.

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.