Outcomes and bleb-related complications of trabeculectomy

PURPOSE

To determine rates of success and complications of trabeculectomy surgery.

DESIGN

Case series.

PARTICIPANTS

Consecutive patients undergoing trabeculectomy by 2 surgeons between May 2000 and October 2008.

INTERVENTION

By using the Wilmer Institute's billing database, we identified all patients at least 12 years of age coded as having undergone trabeculectomy between May 2000 and October 2008 by 1 of 2 glaucoma surgeons and whose surgery was not combined with another operation. From the chart, we abstracted demographic information on the patients and clinical characteristics of the eyes. The Kaplan-Meier product-limit method and Cox proportional hazard models were used to look at success rates and characteristics associated with inadequate intraocular pressure (IOP) reduction. Complications were tabulated.

MAIN OUTCOME MEASURES

(1) Success rate of trabeculectomy, as determined by the achievement of each of 4 different IOP goals, with or without IOP-lowering medications; and (2) incidence of surgical complications.

RESULTS

During the study period, 797 eyes of 634 persons underwent trabeculectomy without concurrent surgery. The success rates 4 years after surgery, with or without the use of IOP-lowering eye drops, were 70%, 72%, 60%, and 44%, for achievement of target IOP, ≤18 mmHg and ≥20% IOP reduction, ≤15 mmHg and ≥25% reduction, and ≤12 mmHg and ≥30% reduction, respectively. Increased chance of success was associated with European-derived race; use of mitomycin C (MMC); higher concentrations of MMC, when used; and higher preoperative IOP. Age and previous intraocular surgery were not associated with surgical success. Complications included worsening lens opacity in 242 of 443 phakic eyes (55%), loss of ≥3 lines of acuity (Snellen) in 161 eyes (21%), surgery for bleb-related problems in 70 eyes (8.8%), and infection occurring >6 weeks after surgery in 27 eyes (3.4%). A total of 101 eyes of 94 patients had at least 1 subsequent operation for inadequate IOP control.

CONCLUSIONS

Trabeculectomy surgery performed by 2 experienced glaucoma specialists achieved target IOP at 4 years in 70% of those operated and was associated with progressive cataract and small risks of bleb-related complications. These results are comparable to those reported in smaller series.

Collagen structure and mechanical properties of the human sclera: analysis for the effects of age

The objective of this study was to measure the collagen fiber structure and estimate the material properties of 7 human donor scleras, from age 53 to 91. The specimens were subjected to inflation testing, and the full-field displacement maps were measured by digital image correlation. After testing, the collagen fiber structure was mapped using wide-angle X-ray scattering. A specimen-specific inverse finite element method was applied to calculate the material properties of the collagen fibers and interfiber matrix by minimizing the difference between the experimental displacements and model predictions. Age effects on the fiber structure and material properties were estimated using multivariate models accounting for spatial autocorrelation. Older age was associated with a larger matrix stiffness (p = 0.001), a lower degree of fiber alignment in the peripapillary sclera (p = 0.01), and a lower mechanical anisotropy in the peripapillary sclera (p = 0.03).

Studies of scleral biomechanical behavior related to susceptibility for retinal ganglion cell loss in experimental mouse glaucoma

PURPOSE

To study anatomical changes and mechanical behavior of the sclera in mice with experimental glaucoma by comparing CD1 to B6 mice.

METHODS

Chronic experimental glaucoma for 6 weeks was produced in 2- to 4-month-old CD1 (43 eyes) and B6 mice (42 eyes) using polystyrene bead injection into the anterior chamber with 126 control CD1 and 128 control B6 eyes. Intraocular pressure (IOP) measurements were made with the TonoLab at baseline and after bead injection. Axial length and scleral thickness were measured after sacrifice in the CD1 and B6 animals and compared to length data from 78 eyes of DBA/2J mice. Inflation testing of posterior sclera was conducted, and circumferential and meridional strain components were determined from the displacement response.

RESULTS

Experimental glaucoma led to increases in axial length and width by comparison to fellow eyes (6% in CD1 and 10% in B6; all P < 0.03). While the peripapillary sclera became thinner in both mouse types with glaucoma, the remainder of the sclera uniformly thinned in CD1, but thickened in B6. Peripapillary sclera in CD1 controls had significantly greater temporal meridional strain than B6 and had differences in the ratios of meridional to effective circumferential strain from B6 mice. In both CD1 and B6 mice, exposure to chronic IOP elevation resulted in stiffer pressure-strain responses for both the effective circumferential and meridional strains (multivariable regression model, P = 0.01-0.03).

CONCLUSIONS

Longer eyes, greater scleral strain in some directions at baseline, and generalized scleral thinning after glaucoma were characteristic of CD1 mice that have greater tendency to retinal ganglion cell damage than B6 mice. Increased scleral stiffness after glaucoma exposure in mice mimics findings in monkey and human glaucoma eyes.

Difficulty with out-loud and silent reading in glaucoma

PURPOSE

We evaluated the impact of glaucoma on out-loud and silent reading. METHODS. Glaucoma patients with bilateral visual field (VF) loss and normally-sighted controls had the following parameters measured: speed reading an International Reading Speed Text (IReST) passage out loud, maximum out-loud MNRead chart reading speed, sustained (30 minutes) silent reading speed, and change in reading speed during sustained silent reading.

RESULTS

Glaucoma subjects read slower than controls on the IReST (147 vs. 163 words per minute [wpm], P < 0.001), MNRead (172 vs. 186 wpm, P < 0.001), and sustained silent (179 vs. 218 wpm, P < 0.001) tests. In multivariable analyses adjusting for age, race, sex, education, employment, and cognition, IReST and MNRead reading speeds were 12 wpm (6%-7%) slower among glaucoma subjects compared to controls (P < 0.01 for both), while sustained silent reading speed was 16% slower (95% confidence interval [CI] = -24 to -6%, P = 0.002). Each 5 decibel (dB) decrement in better-eye VF mean deviation was associated with 6 wpm slower IReST reading (95% CI = -9 to -3%, P < 0.001), 5 wpm slower MNRead reading (95% CI = -7 to -2%, P < 0.001), and 9% slower sustained silent reading (95% CI = -13 to -6%, P < 0.001). A reading speed decline of 0.5 wpm/min or more over the sustained silent reading period was more common among glaucoma subjects than controls (odds ratio [OR] = 2.2, 95% CI = 1.0-4.9, P < 0.05).

CONCLUSIONS

Reading speed is slower among glaucoma patients with bilateral VF loss, with the greatest impact present during sustained silent reading. Persons with glaucoma fatigue during silent reading, resulting in slower reading over time.

Automated telecommunication-based reminders and adherence with once-daily glaucoma medication dosing: the automated dosing reminder study

IMPORTANCE

Topical glaucoma medications lower intraocular pressure and alter the course of the disease. Because adherence with glaucoma medications is a known problem, interventions are needed to help those patients who do not take their medications as prescribed.

OBJECTIVE

To assess the ability of an automated telecommunication-based intervention to improve adherence with glaucoma medications.

DESIGN, SETTING, AND PARTICIPANTS

We performed a prospective cohort study of medication adherence, followed by a randomized intervention for those found to be nonadherent, of individuals recruited from a university-based glaucoma subspecialty clinic. A total of 491 participants were enrolled in the initial assessment of adherence. Of those, 70 were nonadherent with their medications after 3 months of electronic monitoring and randomized to intervention and control groups.

INTERVENTIONS

A personal health record was used to store the list of patient medications and reminder preferences. On the basis of those data, participants randomized to the intervention received daily messages, either text or voice, reminding them to take their medication. Participants randomized to the control group received usual care.

MAIN OUTCOMES AND MEASURES

Difference in adherence before and after initiation of the intervention.

RESULTS

Using an intent-to-treat analysis, we found that the median adherence rate in the 38 participants randomized to the intervention increased from 53% to 64% (P < .05). There was no statistical change in 32 participants in the control group. To assess the real efficacy of the intervention, the same comparison was performed for the participants who successfully completed the study after randomization. Analyzed this way, the adherence rate in the 20 participants in the intervention group increased from 54% to 73% (P < .05), whereas there was again no statistical change in the 19 participants in the control group. Eighty-four percent of the participants who received reminders agreed they were helpful and would continue using them outside the study.

CONCLUSIONS AND RELEVANCE

Automated telecommunication-based reminders linked to data in a personal health record improved adherence with once-daily glaucoma medications. This is an effective method to improve adherence that could realistically be implemented in ophthalmology practices with a minimum amount of effort on the part of the practice or the patient.

Change in choroidal thickness and axial length with change in intraocular pressure after trabeculectomy

BACKGROUND/AIMS

We studied the change in choroidal thickness (CT) and axial length (AL) after intraocular (IOP) changes produced by trabeculectomy.

METHODS

Twenty-one eyes of 20 patients were studied preoperatively, and then postoperatively at 1 week, 1, 3, and 6 months. Variables measured included IOP, AL, keratometry, refractive error, central corneal thickness, and average CT in the posterior 6 mm centred on the fovea using enhanced depth imaging spectral domain optical coherence tomography (OCT).

RESULTS

OCT images in 17 eyes (58 images, preoperatively and postoperatively) were of sufficient quality to determine CT. In every patient, CT increased with IOP lowering postoperatively. For each 1 mmHg decrease in IOP, there was a mean increase of 3.4 µm in CT (p<0.0001; univariate regression, 95% CI 2.5 to 4.3). This represented a CT increase of 1.7% per mm Hg decrease (p<0.0001; 95% CI 1.3 to 2.0%). AL decreased by 6.8 µm per mm Hg decrease in IOP (p<0.0001, univariate regression, 95% CI 4.9 to 8.6).

CONCLUSIONS

The dynamic relationship between change in IOP and the state of sclera and choroid was confirmed by sequential measurements in postoperative trabeculectomy patients, providing estimates of the magnitude of choroidal swelling and scleral volume decrease with IOP lowering.

Studies of transformer repair workers exposed to PCBs: II. Results of clinical laboratory investigations

Thirty-eight transformer repairmen currently exposed to polychlorinated biphenyls (PCBs), 17 former transformer repairmen, and 56 comparison workers not known to be exposed to PCBs were studied. Measurements were made of serum liver function tests, gamma-glutamyl transpeptidase (GGT), lipid profile, thyroid function tests, and other serum biochemistry; hemoglobin; white cell count; 24-hour excretion of delta-aminolevulinic acid, porphyrins, 17-hydroxycorticosteriods and 17-ketosteroids; sperm count; spirometry; and antipyrine half-life to evaluate microsomal mixed function oxidase induction. The total exposed group differed significantly from the comparison group in albumin, LDH, T4, T4-RT3 index, and actual/predicted FEV1. Significant differences among all three exposure groups were seen for albumin, T4, T4-RT3 index, and 17-hydroxycorticosteroid excretion. Differences in FEV1 were attributable to smoking. Significant correlations between serum PCBs and serum lipids were removed by adjustment for confounding variables. After adjustment for confounding variables, there was a statistically significant positive correlation between serum PCBs and GGT and a negative correlation between adipose PCBs and 17-hydroxycorticosteroid excretion. These may reflect subtle metabolic effects of PCBs.

The choroid is thicker in angle closure than in open angle and control eyes

PURPOSE

To study factors associated with choroidal thickness (CT) and to compare CT in angle closure (AC), open angle (OA), and normal eyes.

METHODS

Forty controls, 106 OA, and 79 AC subjects underwent measurements of posterior CT by spectral domain-optical coherence tomography, and of intraocular pressure (IOP), blood pressure, axial length (AL), and central corneal thickness (CCT).

RESULTS

CT was significantly greater in AC than in OA and normal eyes (HSD test, P ≤ 0.05), but there was no significant difference between OA and normal CT; mean CT was 234, 235, and 318 μm in the normal, OA, and AC groups, respectively. With multivariable analysis among all participants, thinner CT was associated with older age, longer AL, higher IOP, and thicker CCT (all P ≤ 0.03, R(2) = 0.45). Adjusting for other relevant variables, the AC group had a significantly greater CT than either the normal or the OA group (P = 0.003 and 0.03, respectively). In multivariable analysis including only OA and AC patients, neither cup-to-disc ratio nor visual field mean deviation were significantly associated with CT. Multivariable analysis for CT among normal eyes found longer AL to be associated with thinner CT (P = 0.04).

CONCLUSIONS

AC eyes had significantly thicker CT than OA and normal eyes, even after adjusting for the shorter AL in AC eyes, supporting hypotheses that choroidal expansion contributes to the development of AC disease. Age, AL, CCT, and IOP were also significantly associated with CT, while severity of glaucoma damage was not.

The pressure-induced deformation response of the human lamina cribrosa: Analysis of regional variations

The objective of this study was to measure the pressure-induced deformation response of the human lamina cribrosa (LC) and analyze for variations with age and anatomical region. The posterior scleral cup of 8 eyes from 6 human donors was mounted onto a custom inflation chamber. A laser-scanning microscope was used for second harmonic generation (SHG) imaging of the collagen structure in the posterior volume of the LC at pressures from 5mmHg to 45mmHg. The SHG volumes were analyzed by the Fast-Fourier Iterative Digital Volume Correlation (DVC) algorithm for the three dimensional (3D) displacement field. The components of the Green-Lagrange strain tensor and the in-plane principal and maximum shear strains were evaluated from the DVC displacement field for the central and peripheral regions of the LC and the nasal, temporal, inferior, and superior quadrants surrounding the central retinal artery and vein. Among the major findings were that older age was associated with lower strains, the maximum shear strain was larger in the peripheral than central region, and the maximum principal strain was lower in the nasal quadrant. The elliptical shape of the LC was also predictive of the biaxial strain ratio. Age-related and structure-related variations in the pressure-induced strains of the LC may contribute to the susceptibility and severity of optic nerve damage in glaucoma, and regional variations may explain the progression of axonal damage and tissue remodeling observed in the LC in glaucoma.

STATEMENT OF SIGNIFICANCE

Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa (LC), the connective tissue structure that supports the axons as they leave the eye. Mechanical characterization of the LC is challenging because of the complex 3D shape and inaccessibility of the tissue. We present a new method using digital volume correlation to map the 3D displacement and strain fields in the LC under inflation. We report for the first time significant regional variations in the strains that are consistent with the pattern of optic nerve damage in early glaucoma. Thus regional strain variations may be predictive of the progression of axonal damage in glaucoma.

Comparison of limbus-based and fornix-based trabeculectomy: success, bleb-related complications, and bleb morphology

PURPOSE

To compare the success and complications of trabeculectomy performed with limbus-based and fornix-based conjunctival approaches.

DESIGN

Retrospective case series with some prospective data collection.

PARTICIPANTS

Consecutive patients undergoing trabeculectomy by 2 surgeons between May 2000 and October 2008.

INTERVENTION

We performed limbus-based operations during the first 4 years and fornix-based operations during the last 4 years. We collected data by chart review and by examination at the most recent visit. For each follow-up visit, we defined success as undergoing no further glaucoma procedure and achieving one of our intraocular pressure (IOP) criteria. We used Kaplan-Meier survival analysis, Cox proportional hazards models, and generalized estimating equation (GEE) analysis. During 2009, 439 trabeculectomy sites of 347 patients were quantitatively assessed by the Indiana bleb grading system.

MAIN OUTCOME MEASURES

(1) Success rate of trabeculectomy, as determined by the achievement of each of our different IOP goals, with or without IOP-lowering medications; and (2) incidence of surgical complications.

RESULTS

During the 4 years after surgery, the success rates of limbus-based and fornix-based trabeculectomy were not statistically different for any of our IOP criteria. Blebs after limbus-based surgery were more likely to be graded as higher and to be avascular (GEE model, both P < 0.0001). Four percent of eyes experienced late-onset bleb leaks within 4 years after both limbus- and fornix-based operations; however, limbus-based cases developed bleb leaks significantly later than did fornix-based cases (2.1 vs. 1.0 years; P=0.002, GEE model). Late bleb-associated infection during the first 4 years after surgery occurred more often in limbus-based operations, although statistical significance was borderline (P=0.054, Cox model). Symptomatic hypotony during all available follow-up was more common with fornix-based operations (P=0.01, GEE model). Eyes undergoing the fornix-based operation had a greater risk of cataract surgery in the 4-year period after surgery (P=0.02, Cox model), and fornix-based cases requiring cataract surgery had the operation earlier than limbus-based cases (P=0.002, GEE model).

CONCLUSIONS

Success rates are similar between limbus-based and fornix-based trabeculectomy. Limbus-based procedures produce higher, more avascular blebs, with a greater risk of infection. Fornix-based procedures have more symptomatic hypotony and more and earlier cataract development.

Choroidal thickness change after water drinking is greater in angle closure than in open angle eyes

PURPOSE

To study change in choroidal thickness (CT) after water drinking test (WDT), comparing angle closure (AC) to open angle (OA) eyes.

METHODS

Before and 30 minutes after drinking 1 L of water, 88 glaucoma subjects underwent measurements of CT by spectral domain-optical coherence tomography, IOP, blood pressure (BP), axial length (AL), and anterior chamber depth (ACD).

RESULTS

Baseline CT was significantly greater in AC than in OA eyes (P = 0.002). After WDT, BP, IOP, and AL increased significantly (all P ≤ 0.0001). Mean CT increased significantly in the AC group (5.6 μm, P = 0.04, n = 40) and among 80 subjects whose IOP rose > 2 mm Hg (responders; 3.2 μm, P = 0.048), but not in the OA group or among all subjects (2.5 μm increase overall, <1% of baseline CT, P = 0.10). ACD decreased in AC (-18 μm, P = 0.07), but not in OA eyes (+3 μm, P = 0.74). AC eyes had a significantly greater IOP increase after WDT than OA eyes (P = 0.002, multivariate regression). Among responders, CT increased more in those with larger diastolic perfusion pressure increase and in AC compared to OA eyes (P = 0.04 and P = 0.053, respectively, multivariate regression).

CONCLUSIONS

A significant increase in CT and a decrease in ACD after WDT were observed in AC but not in OA eyes, and IOP increased significantly more in AC than in OA eyes, suggesting that the dynamic behavior of the choroid may play a role in the AC process. IOP increase after the WDT was not fully explained by CT increase.

The relationship between better-eye and integrated visual field mean deviation and visual disability

OBJECTIVE

To determine the extent of difference between better-eye visual field (VF) mean deviation (MD) and integrated VF (IVF) MD among Salisbury Eye Evaluation (SEE) subjects and a larger group of glaucoma clinic subjects and to assess how those measures relate to objective and subjective measures of ability/performance in SEE subjects.

DESIGN

Retrospective analysis of population- and clinic-based samples of adults.

PARTICIPANTS

A total of 490 SEE and 7053 glaucoma clinic subjects with VF loss (MD ≤-3 decibels [dB] in at least 1 eye).

METHODS

Visual field testing was performed in each eye, and IVF MD was calculated. Differences between better-eye and IVF MD were calculated for SEE and clinic-based subjects. In SEE subjects with VF loss, models were constructed to compare the relative impact of better-eye and IVF MD on driving habits, mobility, self-reported vision-related function, and reading speed.

MAIN OUTCOME MEASURES

Difference between better-eye and IVF MD and relationship of better-eye and IVF MD with performance measures.

RESULTS

The median difference between better-eye and IVF MD was 0.41 dB (interquartile range [IQR], -0.21 to 1.04 dB) and 0.72 dB (IQR, 0.04-1.45 dB) for SEE subjects and clinic-based patients with glaucoma, respectively, with differences of ≥ 2 dB between the 2 MDs observed in 9% and 18% of the groups, respectively. Among SEE subjects with VF loss, both MDs demonstrated similar associations with multiple ability and performance metrics as judged by the presence/absence of a statistically significant association between the MD and the metric, the magnitude of observed associations (odds ratios, rate ratios, or regression coefficients associated with 5-dB decrements in MD), and the extent of variability in the metric explained by the model (R(2)). Similar associations of similar magnitude also were noted for the subgroup of subjects with glaucoma and subjects in whom better-eye and IVF MD differed by ≥ 2 dB.

CONCLUSIONS

The IVF MD rarely differs from better-eye MD, and similar associations between VF loss and visual disability are obtained using either MD. Unlike better-eye MD, IVF measurements require extra software/calculation. As such, information from studies using better-eye MD can be more easily integrated into clinical decision-making, making better-eye MD a robust and meaningful method for reporting VF loss severity.

The effects of glycosaminoglycan degradation on the mechanical behavior of the posterior porcine sclera

Pathological changes in scleral glycosaminoglycan (GAG) content and in scleral mechanical properties have been observed in eyes with glaucoma and myopia. The purpose of this study is to investigate the effect of GAG removal on the scleral mechanical properties to better understand the impact of GAG content variations in the pathophysiology of glaucoma and myopia. We measured how the removal of sulphated GAG (s-GAG) affected the hydration, thickness and mechanical properties of the posterior sclera in enucleated eyes of 6-9 month-old pigs. Measurements were made in 4 regions centered on the optic nerve head (ONH) and evaluated under 3 conditions: no treatment (control), after treatment in buffer solution alone, and after treatment in buffer containing chondroitinase ABC (ChABC) to remove s-GAGs. The specimens were mechanically tested by pressure-controlled inflation with full-field deformation mapping using digital image correlation (DIC). The mechanical outcomes described the tissue tensile and viscoelastic behavior. Treatment with buffer alone increased the hydration of the posterior sclera compared to controls, while s-GAG removal caused a further increase in hydration compared to buffer-treated scleras. Buffer-treatment significantly changed the scleral mechanical behavior compared to the control condition, in a manner consistent with an increase in hydration. Specifically, buffer-treatment led to an increase in low-pressure stiffness, hysteresis, and creep rate, and a decrease in high-pressure stiffness. ChABC-treatment on buffer-treated scleras had opposite mechanical effects than buffer-treatment on controls, leading to a decrease in low-pressure stiffness, hysteresis, and creep rate, and an increase in high-pressure stiffness and transition strain. Furthermore, s-GAG digestion dramatically reduced the differences in the mechanical behavior among the 4 quadrants surrounding the ONH as well as the differences between the circumferential and meridional responses compared to the buffer-treated condition. These findings demonstrate a significant effect of s-GAGs on both the stiffness and time-dependent behavior of the sclera. Alterations in s-GAG content may contribute to the altered creep and stiffness of the sclera of myopic and glaucoma eyes.

Biomechanical Responses of Lamina Cribrosa to Intraocular Pressure Change Assessed by Optical Coherence Tomography in Glaucoma Eyes

Purpose

The purpose of this study was to measure change in anterior lamina cribrosa depth (ALD) globally and regionally in glaucoma eyes at different intraocular pressures (IOP).

Methods

Twenty-seven glaucoma patients were imaged before and after IOP-lowering procedures using optical coherence tomography. The anterior lamina was marked in approximately 25 locations in each of six radial scans to obtain global and regional estimates of ALD. ALD and its change with IOP were compared with optic disc damage, nerve fiber layer thickness, and visual field loss.

Results

Variables associated with deeper baseline ALD included larger cup/disc ratio, thinner rim area, larger cup volume, thinner central corneal thickness, and male sex (all P ≤ 0.02). When IOP was lowered, ALD position became more anterior, more posterior, or was unchanged. The mean ALD change after lowering was 27 ± 142 μm (P = 0.3). The mean absolute value of ALD change was 112 ± 90 μm (P = 0.002). Change in ALD was greater in eyes with lower IOP in paired comparisons (P = 0.006) but was not associated with the magnitude of IOP lowering between imaging sessions (P = 0.94). Eyes with no significant change in ALD tended to have more visual field loss than those with significant anterior ALD displacement (P = 0.07). Areas within each optic nerve head that corresponded to zones with thicker nerve fiber layer had greater ALD positional change (P = 0.0007).

Conclusions

The lamina can move either anteriorly or posteriorly with IOP decrease, with greater displacement at lower IOP. Glaucoma eyes and regions within glaucoma eyes associated with greater glaucoma damage exhibited smaller responses.

Incident choroidal neovascularization in fellow eyes of patients with unilateral subfoveal choroidal neovascularization secondary to age-related macular degeneration: SST report No. 20 from the Submacular Surgery Trials Research Group

OBJECTIVE

To describe incident choroidal neovascular lesions in fellow eyes of participants in the Submacular Surgery Trials who had age-related macular degeneration (AMD).

METHODS

Review of baseline fluorescein angiograms confirmed the absence of neovascular AMD in fellow eyes of 364 participants at risk. Subjects were eligible for a minimum of 2 years of follow-up with angiograms of eyes at risk reevaluated to estimate incidence rates of choroidal neovascularization (CNV) and to characterize these lesions.

MAIN OUTCOME MEASURES

Incidence of CNV during follow-up, characteristics of the incident lesion (composition, size, and location), and visual acuity at the time of incidence.

RESULTS

Incident lesions were confirmed in 98 fellow eyes of participants, yielding 2- and 4-year cumulative incidence rates of 22% and 37%. Incident lesions were predominantly CNV in 87 fellow eyes (90%), extrafoveal in 29 fellow eyes (30%), and juxtafoveal in 9 fellow eyes (9%). Occult without classic CNV lesions were found in 64 eyes (67%), minimally classic CNV and predominantly classic CNV lesions in 12 eyes (13%) each, and predominantly blood lesions in 4 eyes (4%). Nearly two-thirds of all incident lesions were 3 disc areas or smaller in size. Median visual acuity decreased from 20/25 at baseline to 20/250 at the 4-year follow-up in fellow eyes with incident CNV. CONCLUSIONS AND APPLICATION TO CLINICAL PRACTICE: Frequent angiographic follow-up of fellow eyes at risk for CNV may lead to earlier detection and treatment of neovascular AMD and better visual acuity outcomes.

Description and validation of a test to evaluate sustained silent reading

PURPOSE

To construct and validate a test of sustained silent reading.

METHODS

Standardized 7300 and 7600 word passages were written to evaluate sustained silent reading. Two hundred forty subjects validated whether comprehension questions could discriminate subjects who did and did not read the passage. To evaluate test-retest properties, 49 subjects silently read the standardized passages on separate days. Sixty glaucoma suspect controls and 64 glaucoma subjects had their out loud reading evaluated with the MNRead card and an International Reading Speed Texts (IReST) passage, and their silent reading measured using the 7300 word passage. Sustained silent reading parameters included reading speed and reading speed slope over time.

RESULTS

Comprehension questions distinguished individuals who had and had not read passage materials. Bland-Altman analyses of intersession sustained reading speed and reading speed slope demonstrated 95% coefficients of repeatability of 57 words per minute (wpm) and 2.76 wpm/minute. Sustained silent reading speed was less correlated with MNRead (r = 0.59) or IReST passage (r = 0.68) reading speeds than the correlation of these two measures of out loud reading speed with each other (r = 0.72). Sustained silent reading speed was more likely to differ from IReST reading speed by more than 50% in rapid silent readers (odds ratio [OR] = 29, 95% confidence interval [CI] = 10-87), and comparisons of sustained and out loud reading speeds demonstrated proportional error in Bland-Altman analyses.

CONCLUSIONS

Tests of out loud reading do not accurately reflect silent reading speed in individuals with normal vision or glaucoma. The described test offers a standardized way to evaluate the impact of eye disease and/or visual rehabilitation on sustained silent reading.

Recruitment in the Hypertension Prevention trial. Hypertension Prevention Trial Research Group

The Hypertension Prevention Trial (HPT) was a randomized, controlled, multicenter (four clinics, four resource centers) trial designed to test the feasibility of achieving and sustaining dietary changes in the intake of calories, sodium, and potassium and to assess the effect of those changes on blood pressure in a normotensive population. The trial involved 841 men and women (plus a test cohort of 78) who, at the first baseline (BL) examination were in the age range of 25-49 years and had diastolic blood pressure (DBP) greater than or equal to 76 but less than 100 mm Hg (average of two readings), and at the examination prior to randomization (BL 2), had DBP greater than or equal to 78 but less than 90 mm Hg (also averaged). Participants were randomly assigned to a control treatment group (no dietary counseling) or to one of four dietary treatment groups involving counseling designed to reduce calorie intake, reduce sodium intake, reduce sodium and calorie intake, and reduce sodium and increase potassium intake. This chapter describes the process of recruiting participants for the trial. Methods used to identify and contact study participants are presented. Details of the steps involved in the recruitment process and strategies for reducing costs are discussed.

Progression of age-related macular degeneration after cataract surgery

OBJECTIVE

To document age-related macular degeneration (AMD) progression after cataract surgery.

METHODS

Surgeons prospectively enrolled patients with nonneovascular AMD who were awaiting cataract surgery. Fluorescein angiography was performed preoperatively and at the postoperative week 1, month 3, and month 12 visits. Incidence of neovascular AMD development within 12 months after operation was the primary outcome measure.

RESULTS

A total of 108 subjects were enrolled. Of 86 eyes with preoperatively photographically confirmed nonneovascular AMD, 71 had gradable images by month 12. Neovascular AMD was observed in 9 of 71 eyes (12.7%; 95% confidence interval, 6.0%-22.7%). The progression rate between week 1 and month 12 decreased to 3 of 65 eyes (4.6%; 95% confidence interval, 1.0%-12.9%) after excluding 5 neovascular events identified on the postoperative week 1 visit and 1 case with missing photographs at this visit.

CONCLUSION

The low incidence rate of neovascular AMD development between 1 week and 1 year after cataract surgery did not support the hypothesis that cataract surgery increases the risk of AMD progression. Several eyes appeared to have disease progression on postsurgery week 1 fluorescein angiograms, suggesting that many cases of presumed progression to neovascular AMD following cataract surgery may have been present prior to cataract surgery, but not recognized owing to lens opacity.

Comparison of dynamic changes in anterior ocular structures examined with anterior segment optical coherence tomography in a cohort of various origins

PURPOSE

To identify risk factors associated with primary angle closure (AC) using anterior segment optical coherence tomography (ASOCT) measurements of the iris and to determine if these risk factors differ according to geographic origin.

METHODS

Anterior segment OCT images were collected on 267 persons (eyes) whose family origin was determined by a standardized method. In the 257 eyes with pupil diameter increase in the dark of 0.5 mm or more, findings were compared between bright light conditions and those in a dark room. In 130 eyes, comparison was made after pharmacological pupil dilation. After marking the position of the scleral spur, an automated program quantified many angle and iris parameters, with use of a manual method for a minority that the software could not analyze.

RESULTS

Iris area in bright light was larger with increasing age (univariate regression, P = 0.0005), largest in European and African-derived, and smallest in Korean and Chinese eyes (multivariable regression, P = 0.0001), and was significantly larger in AC groups compared with normal and open angle glaucoma groups (univariate regression, P < 0.0001). The absolute iris area loss per mm pupil dilation was significantly less in Chinese persons than African-derived persons (multivariable regression, P < 0.05 adjusted Tukey). Furthermore, in persons with past acute AC attack, the baseline iris area was not different from others, but their iris area lost per millimeter dilation was significantly less than in persons without past acute AC attack (multivariable regression, P = 0.04). The odds of AC disease significantly increased in eyes with smaller percent iris area lost and percent iris area lost per millimeter pupil increase, but when adjusted for geographic origin, this was significant only in persons of Chinese origin (interaction regression model). Apparent gain of iris volume on pupil dilation, due to an artifact in calculation from iris area loss, may indicate a detrimental shift in iris tissue toward the angle.

CONCLUSIONS

Chinese persons in this cohort had relatively low baseline iris area, but less loss of iris area on pupil dilation than other groups, a feature also associated with greater prevalence of past acute AC attack. Disproportionate peripheral redistribution of iris area on dilation may contribute to AC.

Studies of transformer repair workers exposed to PCBs: I. Study design, PCB concentrations, questionnaire, and clinical examination results

A cross-sectional study compared 55 transformer repairmen, 38 currently, and 17 previously exposed to polychlorinated biphenyls (PCBs) with 56 non-exposed subjects. PCBs exposures occurred from air and contaminated surfaces, predominantly from Aroclor 1260 with some exposure to Aroclor 1242. Each worker underwent: a questionnaire; standardized medical examination; delayed hypersensitivity testing; and determination of serum and adipose tissue lipid total PCB concentrations. Adipose and serum [PCBs] were significantly higher in the currently exposed, but previously exposed workers did not differ significantly from comparison subjects. No subjects had a classical syndrome of PCB poisoning. A number of neurobehavioral and irritant symptoms were significantly more prevalent in the exposed group, but were probably not related to PCBs. Comedones were more frequent in the exposed group, but no evidence of classical chloracne was noted. Cutaneous delayed hypersensitivity responses to mumps and to trichophyton antigens did not differ between the groups. The association of PCBs with job functions were explored.

Effects of age and diabetes on scleral stiffness

The effects of diabetes on the collagen structure and material properties of the sclera are unknown but may be important to elucidate whether diabetes is a risk factor for major ocular diseases such as glaucoma. This study provides a quantitative assessment of the changes in scleral stiffness and collagen fiber alignment associated with diabetes. Posterior scleral shells from five diabetic donors and seven non-diabetic donors were pressurized to 30 mm Hg. Three-dimensional surface displacements were calculated during inflation testing using digital image correlation (DIC). After testing, each specimen was subjected to wide-angle X-ray scattering (WAXS) measurements of its collagen organization. Specimen-specific finite element models of the posterior scleras were generated from the experimentally measured geometry. An inverse finite element analysis was developed to determine the material properties of the specimens, i.e., matrix and fiber stiffness, by matching DIC-measured and finite element predicted displacement fields. Effects of age and diabetes on the degree of fiber alignment, matrix and collagen fiber stiffness, and mechanical anisotropy were estimated using mixed effects models accounting for spatial autocorrelation. Older age was associated with a lower degree of fiber alignment and larger matrix stiffness for both diabetic and non-diabetic scleras. However, the age-related increase in matrix stiffness was 87% larger in diabetic specimens compared to non-diabetic controls and diabetic scleras had a significantly larger matrix stiffness (p = 0.01). Older age was associated with a nearly significant increase in collagen fiber stiffness for diabetic specimens only (p = 0.06), as well as a decrease in mechanical anisotropy for non-diabetic scleras only (p = 0.04). The interaction between age and diabetes was not significant for all outcomes. This study suggests that the age-related increase in scleral stiffness is accelerated in eyes with diabetes, which may have important implications in glaucoma.

Defining glaucomatous optic neuropathy using objective criteria from structural and functional testing

BACKGROUND/AIMS

To identify objective criteria from optical coherence tomography (OCT) and perimetry that denote a useful, specific definition of glaucomatous optic neuropathy (GON) in eyes with open-angle glaucoma for comparisons among glaucoma research studies.

METHODS

A cross-sectional study of adult patients with glaucoma from nine centres on five continents evaluated de-identified physician diagnosis, OCT and perimetry results for 2580 eyes (1531 patients) in an online database. Each eye was graded by their glaucoma specialist as either definite, probable or not GON. Objective measures from OCT and perimetry, derived from an online consensus panel comprising 176 glaucoma specialists globally, were compared against the three diagnostic levels.

RESULTS

Diagnoses were 54% 'definite', 22% 'probable' and 24% 'not GON'. Using only OCT data or only field data had inadequate specificity (<90%). The best definitional choice for data from either the most recent or the preceding OCT/field pair had 77% sensitivity at 98% specificity and consisted of abnormal OCT superior or inferior nerve fibre layer quadrant with matching, opposite, abnormal Glaucoma Hemifield Test.

CONCLUSIONS

Objective criteria to define GON are practical and may be useful for comparisons among clinical studies to supplement subjective clinical assessment.

The inflation response of the human lamina cribrosa and sclera: Analysis of deformation and interaction

This study investigated the inflation response of the lamina cribrosa (LC) and adjacent peripapillary sclera (PPS) in post-mortem human eyes with no history of glaucoma. The posterior sclera of 13 human eyes from 7 donors was subjected to controlled pressurization between 5-45 mmHg. A laser-scanning microscope (LSM) was used to image the second harmonic generation (SHG) response of collagen and the two-photon fluorescent (TPF) response of elastin within the volume of the LC and PPS at each pressure. Image volumes were analyzed using digital volume correlation (DVC) to calculate the three-dimensional (3D) deformation field between pressures. The LC exhibited larger radial strain, Err, and maximum principal strain, Emax, (p < 0.0001) and greater posterior displacement (p=0.0007) compared to the PPS between 5-45 mmHg, but had similar average circumferential strain, Eθθ, and maximum shear strain, Γmax. The Emax and Γmax were highest near the LC-PPS interface and lowest in the nasal quadrant of both tissues. Larger LC area was associated with smaller Emax in the peripheral LC and larger Emax in the central LC (p ≤ 0.01). The Emax, Γmax, and Eθθ in the inner PPS increased with increasing strain in adjacent LC regions (p ≤ 0.001). Smaller strains in the PPS were associated with a larger difference in the posterior displacement between the PPS and central LC (p < 0.0001 for Emax and Err), indicating that a stiffer pressure-strain response of the PPS is associated with greater posterior bowing of the LC. STATEMENT OF SIGNIFICANCE: Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa (LC), a connective tissue structure that supports the axons as they pass through the eye wall. It is hypothesized that strains caused by intraocular pressure may initiate this damage and that these strains are modulated by the combined deformation of the LC and adjacent peripapillary sclera (PPS). In this study we present a method to measure the pressure-induced 3D displacement and strain field in the LC and PPS simultaneously. Regional strain variation in the LC and PPS was investigated and compared and strains were analyzed for associations with age, LC area, LC strain magnitude, and LC posterior motion relative to the PPS.

Measuring Deformation in the Mouse Optic Nerve Head and Peripapillary Sclera

Purpose

To develop an ex vivo explant system using multiphoton microscopy and digital volume correlation to measure the full-field deformation response to intraocular pressure (IOP) change in the peripapillary sclera (PPS) and in the optic nerve head (ONH) astrocytic structure.

Methods

Green fluorescent protein (GFP)-glutamate transporter-GLT1 (GLT1/GFP) mouse eyes were explanted and imaged with a laser-scanning microscope under controlled inflation. Images were analyzed for regional strains and changes in astrocytic lamina and PPS shape. Astrocyte volume fraction in seven control GLT1/GFP mice was measured. The level of fluorescence of GFP fluorescent astrocytes was compared with glial fibrillary acidic protein (GFAP) labeled astrocytes using immunohistochemistry.

Results

The ONH astrocytic structure remained stable during 3 hours in explants. Control strain-globally, in the central one-half or two-thirds of the astrocytic lamina-was significantly greater in the nasal-temporal direction than in the inferior-superior or anterior-posterior directions (each P≤ 0.03, mixed models). The PPS opening (perimeter) in normal eye explants also became wider nasal-temporally than superior-inferiorly during inflation from 10 to 30 mm Hg (P = 0.0005). After 1 to 3 days of chronic IOP elevation, PPS area was larger than in control eyes (P = 0.035), perimeter elongation was 37% less than controls, and global nasal-temporal strain was significantly less than controls (P = 0.007). Astrocyte orientation was altered by chronic IOP elevation, with processes redirected toward the longitudinal axis of the optic nerve.

Conclusions

The explant inflation test measures the strain response of the mouse ONH to applied IOP. Initial studies indicate regional differences in response to both acute and chronic IOP elevation within the ONH region.

Predictors of lane-change errors in older drivers

OBJECTIVES

To determine the factors that predict errors in executing proper lane changes among older drivers.

DESIGN

Cross-sectional analysis of data from a longitudinal study.

SETTING

Maryland's Eastern Shore.

PARTICIPANTS

One thousand eighty drivers aged 67 to 87 enrolled in the Salisbury Eye Evaluation Driving Study.

MEASUREMENTS

Tests of vision, cognition, health status, and self-reported distress and a driving monitoring system in each participant's car, used to quantify lane-change errors.

RESULTS

In regression models, measures of neither vision nor perceived stress were related to lane-change errors after controlling for age, sex, race, and residence location. In contrast, cognitive variables, specifically performance on the Brief Test of Attention and the Beery-Buktenicka Test of Visual-Motor Integration, were related to lane-change errors.

CONCLUSION

The current findings underscore the importance of specific cognitive skills, particularly auditory attention and visual perception, in the execution of driving maneuvers in older individuals.