Diagnostic accuracy of an iPad application for detection of visual field defects

BACKGROUND/OBJECTIVES

Tablet-based perimetry could be used to test for glaucomatous visual field defects in settings without easy access to perimeters, although few studies have assessed diagnostic accuracy of tablet-based tests. The goal of this study was to determine the diagnostic accuracy of iPad perimetry using the visualFields Easy application.

SUBJECTS/METHODS

This was a prospective, cross-sectional study of patients undergoing their first Humphrey Field Analyser (HFA) visual field test at a glaucoma clinic in India. Participants underwent 24-2 SITA Standard HFA testing and iPad-based perimetry with the visualFields Easy application. Reference standards for both visual field loss and suspected glaucoma were determined by ophthalmologist review of HFA results and optic disc photographs. Receiver operating characteristic curves were constructed to assess diagnostic accuracy at various test thresholds.

RESULTS

203 eyes from 115 participants were included, with 82 eyes classified as moderate or worse glaucoma. iPad perimetry had an area under the receiver operating characteristic (AUROC) curve of 0.64 (95% CI 0.57 to 0.71) for detection of any visual field defect relative to HFA and an AUROC of 0.68 (0.59 to 0.76) for detection of moderate or worse glaucoma relative to ophthalmologist examination. At a set specificity of 90%, the sensitivity of iPad perimetry for detection of moderate or worse glaucoma was 35% (22-48%).

CONCLUSIONS

iPad perimetry using the visualFields Easy application had inadequate diagnostic accuracy to be used as a screening tool for glaucoma in this South Indian population.

Diagnostic Accuracy of Frequency-Doubling Technology and the Moorfields Motion Displacement Test for Glaucoma

PURPOSE

Portable perimetric testing could be useful for community-based glaucoma screening programs. Frequency-doubling technology (FDT) and the Moorfields motion displacement test (MDT) are portable perimeters that have shown promise as potential screening tools for glaucoma. This study's goal was to determine the diagnostic accuracy of FDT and MDT for visual field defects and glaucoma.

DESIGN

Prospective, cross-sectional, diagnostic accuracy study.

PARTICIPANTS

A consecutive series of patients aged ≥ 50 years who presented to a glaucoma clinic in South India and had never undergone Humphrey field analyzer (HFA) visual field testing in the past.

METHODS

Participants underwent 24-2 Swedish Interactive Thresholding Algorithm (SITA) Standard HFA perimetry, FDT perimetry, MDT perimetry, and iPad perimetry using visualFields Easy in random order. Ophthalmologist grades of HFA and optic nerve head photographs were used as reference standards for glaucoma and field defect presence. Receiver operating characteristic curves were constructed to assess the diagnostic accuracy of various parameters for each test.

MAIN OUTCOME MEASURES

Sensitivity, specificity, and area under the receiver operating characteristic curve (AUROC).

RESULTS

Overall, 292 eyes from 173 participants were included, with 112 eyes classified as moderate or worse glaucoma. For moderate or worse glaucoma detection, the best parameter on FDT was mean deviation (MD) (AUROC, 0.84; 95% confidence interval [CI], 0.79-0.89) and the best parameter on MDT was global probability of true damage (GPTD) (AUROC, 0.87; 95% CI, 0.82-0.91). When specificity was set to 90%, the sensitivity for detection of moderate or worse glaucoma was 55% (95% CI, 39%-68%) for FDT MD and 62% (95% CI 52%-71%) for MDT GPTD.

CONCLUSIONS

Frequency-doubling technology and MDT perimetry had fair diagnostic accuracy for glaucoma detection when administered to naïve test takers in this South Indian population. Although not appropriate for use as a sole glaucoma screening test, these perimetric tests may be useful as ancillary tests.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Individuals with and without normal tension glaucoma exhibit comparable performance on tests of cognitive function

AIM

To evaluate aspects of cognition impacted by individuals with and without normal tension glaucoma.

METHODS

Fifty normal tension glaucoma (NTG) and 50 control patients ≥50y of age were recruited from the UCSF Department of Ophthalmology. Demographic data and glaucoma parameters were extracted from electronic medical records for both groups. Tests of executive function [Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (EXAMINER)] and learning and memory [California Verbal Learning Test-Second Edition (CVLT-II)] were administered to both NTG and controls. Race, handedness, best-corrected visual acuity, maximum intraocular pressure, optic nerve cup-to-disc ratio, visual field and optic nerve optical coherence tomography parameters, and a measure of general health (Charlson Comorbidity Index) were compared between NTG and controls as well as within NTG subgroups. Multivariate linear regression was used to compare group performances on the EXAMINER battery and CVLT-II while controlling for age, sex, and years of education.

RESULTS

NTG and controls were comparable with respect to age, sex, race, education, handedness, and the Charlson Comorbidity Index (P>0.05 for all). Performance on the EXAMINER composite score and the CVLT-II did not differ between NTG and controls (P>0.05 for both).

CONCLUSION

This is the first prospective study in which the cognitive function of subject with NTG were evaluated using a comprehensive, computerized neurocognitive battery. Subjects with NTG do not perform worse than unaffected controls on tests of executive function, learning, and memory. Results do not support the hypothesis that individuals with NTG are at higher risk for cognitive dysfunction and/or dementia.

Comparison of Structural, Functional, Tonometric, and Visual Acuity Testing for Glaucoma: A Prospective Diagnostic Accuracy Study

PURPOSE

To determine the diagnostic accuracy of potential screening tests for moderate to advanced glaucoma.

DESIGN

Prospective diagnostic test accuracy study.

PARTICIPANTS

The study enrolled a consecutive series of patients aged ≥50 years who presented to a glaucoma clinic in South India without ever having received automated visual field testing.

METHODS

All participants underwent 8 index tests: OCT of the peripapillary retinal nerve fiber layer, optic disc photography, Moorfield's Motion Displacement Test (MDT), frequency doubling technique perimetry, noncontact tonometry, pneumatonometry, presenting visual acuity, and best-corrected visual acuity. Participants also underwent stereoscopic photographs and Humphrey visual fields, which were used by 2 ophthalmologists to arrive at the reference standard diagnosis of moderate to advanced glaucoma.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio.

RESULTS

A total of 217 people were enrolled; 321 eyes from 180 participants had all tests performed. Of these, 127 eyes (40%) were classified as having moderate to advanced glaucoma. Among the 8 tests, OCT best optimized sensitivity (84%, 95% confidence interval [CI], 76-90) and specificity (75%, 95% CI, 68-81). Moorfield's Motion Displacement Test was the best perimetric test, with a sensitivity of 91% (95% CI, 85-96) and specificity of 53% (95% CI, 44-61). Pressure and vision tests were not sensitive (e.g., sensitivity of 16%, 95% CI, 9-23 for noncontact tonometry and 23%, 95% CI, 15-31 for best-corrected visual acuity). Moorfield's Motion Displacement Test identified 16 of 127 eyes (13%) with glaucoma that were not captured by OCT, but also had false-positive results in 65 of 194 eyes (34%) without glaucoma that OCT correctly classified as negative.

CONCLUSIONS

OCT had moderate sensitivity and fair specificity for diagnosing moderate to advanced glaucoma and should be prioritized during an initial assessment for glaucoma.

Asymmetric Functional Impairment of ON and OFF Retinal Pathways in Glaucoma

Purpose

To investigate ON-pathway versus OFF-pathway dysfunction in glaucoma using handheld electroretinography (ERG) with a temporally modulated sinusoidal flicker stimulus.

Design

Cross-sectional study.

Participants

Fifty-nine participants accounting for 104 eyes, comprised of 19 control eyes, 26 glaucoma suspect eyes, and 59 glaucoma eyes.

Methods

Participants underwent portable ERG testing, which included the photopic flash, photopic flicker, photopic negative response stimulus, ON-OFF stimulus, and a custom-written sinusoidal flicker stimulus that was modulated from 50 to 0.3 Hz.

Main Outcome and Measures

The ERG response amplitudes were measured by the handheld ERG. For the custom-written sinusoidal flicker stimulus, we derived and compared the log10 first harmonic frequency response amplitudes. Patient discomfort and fatigue after ERG testing were rated on a scale from 1 to 5.

Results

Baseline demographics were not significantly different between groups, except for ocular characteristics. Analysis was performed adjusting for participant age, sex, race, and dilation status, and the sinusoidal frequency responses were stratified at 10 Hz because higher frequencies are associated with the OFF-pathway, whereas lower frequencies are associated with the ON-pathway. After stratification, glaucoma eyes showed an adjusted decrease of 32.1% at frequencies of more than 10 Hz (95% confidence interval [CI], -51.8% to -4.1%; P = 0.03). For 10 Hz stimulus frequencies or less, an adjusted 11.5% reduction was found (95% CI, -39.5% to 29.1%; P = 0.50). Glaucoma suspect eyes did show a decreased response, but this was not significant at either frequency range. When comparing handheld ERG with traditional visual field assessments, participants found the handheld ERG to result in much less discomfort and fatigue.

Conclusions

Our finding that glaucoma participants showed greater decreases in ERG response at higher frequencies supports the hypothesis that the OFF-pathway may be more vulnerable in human glaucoma. Using a handheld ERG device with a sinusoidal flicker stimulus may provide an objective assessment of visual function in glaucoma.

Accuracy of autorefraction in an adult Indian population

Purpose

Autorefractors allow non-specialists to quickly assess refractive error, and thus could be a useful component of large-scale vision screening programs. In order to better characterize the role of autorefraction for public health outreach programs in resource-limited settings, the diagnostic accuracy of two autorefractors was assessed relative to subjective refraction in an adult Indian population.

Methods

An optometrist refracted a series of patients aged ≥50 years at an eye clinic in Bangalore, India using the Nidek ARK-900 autorefractor first, followed by the 3nethra Royal autorefractor, and then subjective refraction. The diagnostic accuracy of each autorefractor for myopia, hyperopia, and astigmatism was assessed using subjective refraction as the reference standard, and measures of agreement between refractions were calculated.

Results

A total of 197 eyes in 104 individuals (mean age 63 ± 8 years, 52% female) were evaluated. Both autorefractors produced spherical equivalent estimates that were on average more hyperopic than subjective refraction, with a measurement bias of +0.16 D (95%CI +0.09 to +0.23D) for Nidek and +0.42 D (95%CI +0.28 to +0.54D) for 3nethra. When comparing pairs of measurements from autorefraction and subjective refraction, the limits of agreement were approximately ±1D for the Nidek autorefractor and ±1.75D for the 3Nethra autorefractor. The sensitivity and specificity of detecting ≥1 diopter of myopia were 94.6% (95%CI 86.8–100%) and 92.5% (95%CI 88.9–97.5%) for the Nidek, and 89.2% (95%CI 66.7–97.4) and 77.5% (95%CI 71.2–99.4%) for the 3Nethra. The accuracy of each autorefractor increased at greater levels of refractive error.

Conclusions

The sensitivity and specificity of the Nidek autorefractor for diagnosing refractive error among adults ≥50 years in an urban Indian clinic was sufficient for screening for visually significant refractive errors, although the relatively wide limits of agreement suggest that subjective refinement of the eyeglasses prescription would still be necessary.

Cutaneous melanin and glaucoma: a case control study

Purpose: Previous studies have used subjective assessments to implicate darker skin color as a risk factor for glaucoma. This study used objective measurements to determine whether skin melanin is a risk factor for glaucoma.Methods: In a case-control study conducted at a tertiary eye hospital in Nepal, patients aged 40 years or older from the glaucoma clinic were enrolled as cases and age-matched patients without glaucoma from other clinics at the eye hospital were enrolled as controls. A colorimeter was used to capture melanin measurements in triplicate from the inner arm and forehead of each participant. The exposure variable of interest was the median skin melanin value, in arbitrary units. The outcome of interest was the presence of glaucoma.Results: 100 glaucoma cases and 100 matched controls were enrolled. Agreement between the triplicate melanin measurements was high, with an intra-class correlation of 0.99 (95% CI, 0.99-0.99) for inner arm measurements and 0.97 (95% CI 0.96-0.98) for forehead measurements. Mean inner arm melanin values were 604 units (standard deviation [SD] 177) in cases and 602 units (SD 179) in controls; forehead values were 650 (SD 146) in cases and 652 (SD 152) in controls. After adjusting for sex and country of residence, skin melanin was not associated with the presence of glaucoma (odds ratio 1.04, 95%CI 0.78-1.38 for inner arm values and 0.97, 95%CI 0.70-1.35 for forehead values).Conclusion: This study failed to find a significant association between skin pigmentation and glaucoma.

Short-term Postoperative Visual Acuity Decrease and Recovery after Ahmed Tube Shunt Procedure for Glaucoma

PURPOSE

To elucidate the vision loss and recovery course after the Ahmed tube shunt procedure 6 months postoperatively. To identify risk factors associated with significant vision loss.

DESIGN

Retrospective chart review.

PARTICIPANTS

One eye of all adult patients who underwent an Ahmed glaucoma valve procedure from January 2008 to December 2017 with a minimum 6-month follow-up.

METHODS

Patients' preoperative and postoperative corrected visual acuity (CVA) were documented for 1 week, 1 month, 3 months, and 6 months postoperatively.

MAIN OUTCOME MEASURES

Preoperative and postoperative CVA at various time points were compared using repeated-measures analysis of variance. The proportions of patients with mild (<3 lines of Snellen CVA loss), moderate (3-5 lines, inclusive), and severe (>5 lines) vision loss were calculated and compared using a chi-square test. Logistic regression analysis was conducted to identify risk factors associated with a loss of 3 or more lines of CVA 6 months after surgery.

RESULTS

A total of 375 patients were included, whose mean preoperative CVA was 0.76. At 1 week postoperatively, mean CVA worsened to 0.96 (P < 0.05), but recovered back to preoperative level by the third postoperative month (P > 0.05). In terms of any vision loss, 55.6% of patients had worse CVA than preoperation at 1 week postoperatively, including 23.5% who had 3 or more lines of vision loss; these proportions decreased to 39.2% (P < 0.001) and 9.3%, respectively, by 6 months postoperatively. The most common causes of significant vision loss were preexisting ocular conditions and cataract progression. Postoperative antimetabolite injection was associated with a lower risk of 3 or more lines of CVA loss 6 months postoperatively (odds ratio, 0.44; P = 0.023).

CONCLUSIONS

After the Ahmed tube shunt procedure, the worst CVA occurred at 1 week postoperatively and mean CVA returned to the preoperative level by month 3 postoperatively. Approximately 40% of patients had any CVA loss compared with preoperation, and 9.3% of patients had 3 or more lines of CVA loss at month 6 postoperatively. Postoperative antimetabolite injection was associated with a lower risk of 3 or more lines of postoperative vision loss.

Accuracy of computer-assisted vertical cup-to-disk ratio grading for glaucoma screening

Purpose

Glaucoma screening can be performed by assessing the vertical-cup-to-disk ratio (VCDR) of the optic nerve head from fundus photography, but VCDR grading is inherently subjective. This study investigated whether computer software could improve the accuracy and repeatability of VCDR assessment.

Methods

In this cross-sectional diagnostic accuracy study, 5 ophthalmologists independently assessed the VCDR from a set of 200 optic disk images, with the median grade used as the reference standard for subsequent analyses. Eight non-ophthalmologists graded each image by two different methods: by visual inspection and with assistance from a custom-made publicly available software program. Agreement with the reference standard grade was assessed for each method by calculating the intraclass correlation coefficient (ICC), and the sensitivity and specificity determined relative to a median ophthalmologist grade of ≥0.7.

Results

VCDR grades ranged from 0.1 to 0.9 for visual assessment and from 0.1 to 1.0 for software-assisted grading, with a median grade of 0.4 for each. Agreement between each of the 8 graders and the reference standard was higher for visual inspection (median ICC 0.65, interquartile range 0.57 to 0.82) than for software-assisted grading (median ICC 0.59, IQR 0.44 to 0.71); P = 0.02, Wilcoxon signed-rank test). Visual inspection and software assistance had similar sensitivity and specificity for detecting glaucomatous cupping.

Conclusion

The computer software used in this study did not improve the reproducibility or validity of VCDR grading from fundus photographs compared with simple visual inspection. More clinical experience was correlated with higher agreement with the ophthalmologist VCDR reference standard.

Resident-performed selective laser trabeculoplasty in patients with open-angle glaucoma

IMPORTANCE To our knowledge, this is the first study to investigate effectiveness and complication rates of resident-performed selective laser trabeculoplasty (SLT). OBJECTIVES To evaluate the effectiveness and complications of SLT performed by resident ophthalmologists and to identify predictors for success. DESIGN, SETTING, AND PARTICIPANTS Retrospective case series of 81 patients with open-angle glaucoma undergoing 110 SLT procedures from November 17, 2009, through December 16, 2011, at the San Francisco Veterans Affairs Medical Center. INTERVENTION Resident-performed SLT. MAIN OUTCOMES AND MEASURES Intraocular pressure (IOP) reduction. Secondary outcomes included change in eyedrop medications, complication rates, and predictors of SLT success defined as a 20% reduction in IOP. RESULTS The mean IOP at baseline, defined as the average IOP of the 2 appointments prior to the SLT procedure, was 18.7 mm Hg. The mean decrease in postoperative IOP compared with baseline was 2.2 mm Hg (12%; 95% CI, 5%-19%) at 12 months and 3.3 mm Hg (18%; 95% CI, 13%-23%), 2.8 mm Hg (15%; 95% CI, 10%-21%), and 3.6 mm Hg (19%; 95% CI, 11%-27%) at 3, 6, and 24 months, respectively (all P &lt; .001, linear mixed-effects regression). Success rates were 36% (95% CI, 27%-47%) at 12 months and 41% (95% CI, 31%-53%), 50% (95% CI, 40%-60%), and 39% (95% CI, 26%-53%) at 3, 6, and 24 months, respectively. The most common complication was a temporary IOP spike, with increases of at least 6 mm Hg occurring in 7% (95% CI, 4%-14%) of the population. The largest IOP spike was 11 mm Hg. Increased number of laser shots performed was not associated with better IOP control but was associated with a reduction in number of eyedrop medications (P = .02). Increased baseline IOP was associated with an odds ratio for success of 1.24 (95% CI, 1.08-1.44) at 3 months, 1.20 (95% CI, 1.05-1.37) at 6 months, and 1.31 (95% CI, 1.13-1.53) at 12 months of follow-up (P = .003, P = .006, and P &lt; .001, respectively, logistic regression). In a multivariate analysis, baseline IOP remained the greatest predictor of effectiveness. CONCLUSIONS AND RELEVANCE Resident-performed SLT obtains outcomes similar to the IOP reduction reported in the literature for attending-performed SLT with low levels of complications. Increasing the number of shots in a treatment session may lead to less long-term need for eyedrop medications. In this patient group, higher baseline IOP was the strongest predictor of treatment effectiveness.

Congenital narrow-angle glaucoma and iris nevi in a neonate with epidermal nevus syndrome

Epidermal nevus syndrome (ENS) is a neurocutaneous disorder characterized by epidermal hamartomas and abnormalities of the brain, eye, and other systems. We report the occurrence of congenital angle closure glaucoma in a patient with epidermal nevus syndrome. Intraoperative use of ultrasound biomicroscopy was essential in making the diagnosis.

Repeatability of the multifocal visual evoked potentials in a clinical glaucoma setting

BACKGROUND

To determine the reproducibility of the multifocal visual evoked potentials (mfVEP) test results in a clinical glaucoma setting, and the factors that affect variability.

METHODS

This was an observational case series study. The monocular mfVEP test, having a 58-sector, pattern-reversal dartboard array, was performed twice within 4 weeks in both eyes of 29 adult open-angle glaucoma (OAG) patients and suspects, using AccuMap Opera Software (ObjectiVision Pty Ltd, Sydney, Australia). The AccuMap severity index (ASI), the mean amplitude, and the individual amplitudes in each sector were compared between the 2 tests using intraclass correlations (ICCs). The effects of the severity of mfVEP field defects and signal-to-noise ratio (SNR) on the reproducibility of these variables were determined using the McNemar test and the Spearman rank correlation, respectively.

RESULTS

The average ICCs of the ASI and amplitudes in the 2 tests were 0.84 and 0.87, respectively. Two sectors in the right eye and 6 in the left eye had significant differences between the 2 tests (Wilcoxon signed-rank p < 0.05). Larger differences were observed in patients having lower SNR (Spearman p = 0.022). Forty-six of the 58 eyes stayed within the same diagnosis category on repeating the test (i.e., within normal limits or outside normal limits).

INTERPRETATION

Although there were some isolated examples of clinically significant differences on repeating the mfVEP test in our patients, our results suggest overall good repeat reliability. The variability of the test was higher in patients having high noise levels during the test.

Effect of statin drugs and aspirin on progression in open-angle glaucoma suspects using confocal scanning laser ophthalmoscopy

PURPOSE

To determine the effect of statins and aspirin on the rate of progression of optic nerve parameters in open-angle glaucoma (OAG) suspects, as defined by confocal scanning laser ophthalmoscopy (CSLO).

METHODS

Data of OAG suspects who had undergone at least two CSLO tests at the Beckman Vision Center at UCSF from January 2001 to June 2006 was collected. We conducted a retrospective chart review of 149 eyes from 76 patients considered suspect for glaucoma based on a cup-to-disc ratio >0.5, but with normal intraocular pressures (IOP) and visual fields. Subjects included glaucoma suspects who took statin drugs or aspirin for greater than 23 months. The control group consisted of suspects who never used statins or aspirin. The data were analysed using mixed effects regression.

RESULTS

When comparing controls with the statin group there were significant differences in the progression of multiple CSLO parameters per year, including rim volume (-13.7% controls, +26.7% statin only; P = 0.0156), retinal nerve fibre layer cross-sectional area (-12.2% controls, +24.3% statin only; P = 0.0051), and mean global retinal nerve fibre layer thickness (-10.3% controls, +26.6% statin only; P = 0.0114), with adjustment for age, gender, race, IOP, central corneal thickness, refractive error and multiple systemic comorbidities. No significant differences were found when comparing subjects taking a statin plus aspirin or aspirin alone with the controls.

CONCLUSIONS

Statin drugs may be associated with slowed progression of optic nerve parameters in glaucoma suspects as measured by CSLO.

Acute angle-closure glaucoma due to iris transfixation of a subluxated posterior chamber intraocular lens–capsular bag complex

An 80-year-old woman with pseudoexfoliation syndrome developed subluxation of a posterior chamber intraocular lens (IOL)-capsular bag complex due to zonular rupture. She underwent a limited 25-gauge pars plana vitrectomy and iris transfixation of the subluxated IOL-capsule complex. The postoperative course was uneventful until the patient developed acute angle-closure glaucoma 3 weeks postoperatively. Ultrasound biomicroscopy confirmed pupillary block by the IOL-capsule complex. The patient was treated with intraocular pressure-lowering medications and a vitreous tap before a laser peripheral iridotomy could be performed successfully. The vision returned to normal, and the angle closure resolved. We recommend that a prophylactic surgical iridectomy be performed in patients with iris transfixation of a posterior chamber IOL-capsular bag complex.

Does treated systemic hypertension affect progression of optic nerve damage in glaucoma suspects?

PURPOSE

To evaluate whether treatment of systemic hypertension has an effect on progression of optic nerve parameters in glaucoma suspects using confocal scanning laser ophthalmoscopy.

METHODS

Two hundred eyes of 103 glaucoma suspect patients were included in this retrospective cohort study. Thirty-one patients (of whom 59 eyes were included in the study) had systemic hypertension under treatment (based on medical history). The remaining 72 age-matched normotensive controls (of whom 141 eyes were included in the study) were not on blood-pressure-lowering medications. Each patient had a follow-up period of at least 4 years with a minimum of four Heidelberg retinal tomograph tests (one baseline and three follow-up scans). The slopes of progression of optic nerve head parameters with time were studied and compared between these two groups using mixed effects regression models.

RESULTS

Patients with systemic hypertension showed a statistically significant increase in cup area (slope 0.2, p = 0.03), cup-to-disk area ratio (slope 0.01, p = 0.007), and decrease in rim area (slope -0.4, p = 0.03), rim-to-disk area ratio (slope -0.01, p = 0.005), and global Retinal Nerve Fiber Layer (RNFL) thickness (p = 0.008) with time. The differences in slopes of progression of many parameters between hypertensives and normotensives were statistically significant.

CONCLUSIONS

Systemic hypertension treated with hypotensive medications may be a risk factor for increased progression of optic nerve parameters in glaucoma suspects compared with age-matched normotensive subjects.

Dynamic contour tonometry: principle and use

Interindividual variability of central corneal thickness has been found to be a source of error for conventional Goldmann applanation tonometry. The dynamic contour tonometer represents a potentially new technology for non-invasive and direct intraocular pressure (IOP) measurement, and has been proposed to accurately measure the true IOP irrespective of the corneal thickness. It is based on the principle that when the tip of the device exactly matches the contour of the cornea, the pressure measured by a transducer placed on its tip is an accurate indicator of the true IOP. This device is also capable of measuring the ocular pulse amplitude, a variable that has controversial significance in the diagnosis and management of glaucoma. Even though this technique seems to be very promising, further studies are required to conclusively determine the effectiveness of the dynamic contour tonometer in patients having an abnormal or irregular corneal contour.

Intraocular pressure and ocular pulse amplitude comparisons in different types of glaucoma using dynamic contour tonometry

PURPOSE

To compare the intraocular pressures (IOP) and ocular pulse amplitudes (OPA) in patients with different types of glaucoma, ocular hypertension (OHT), and normal controls (NC) using dynamic contour tonometry (DCT) and the goldmann applanation tonometry (GAT).

METHODS

906 eyes of 501 adult patients in the following five groups were included in this cross-sectional study: primary open angle glaucoma (POAG), normal tension glaucoma (NTG), Pseudoexfoliative Glaucoma (PXG), OHT, and NC. The following tests were performed simultaneously during a single visit: IOP using DCT and GAT; OPA using DCT and central corneal thickness (CCT) using ultrasound pachymetry. Mixed effects regression models were used to compare the DCT and GAT IOP measurements in the five groups; the effect of CCT on IOP and the relationship between OPA and IOP within each group.

RESULTS

DCT consistently had higher IOP values than GAT in POAG, PXG, NTG, and controls (p < 0.001) but not in OHT (p = 0.84). DCT IOP did not change while GAT IOP showed a non-significant increase (p = 0.09) with increased corneal thickness in each group. OPA was found to be highest in OHT (3.61 mmHg) and lowest in the control group (2.86 mmHg) and significantly increased with IOP in all groups.

CONCLUSIONS

DCT measures an IOP that is significantly higher than GAT IOP in glaucoma and control subjects but not in ocular hypertensives. Furthermore, the DCT may measure an IOP that is independent of the CCT, which may not be true for the GAT, which increases with the CCT. OPA was highest in OHT and may be affected by the IOP.

Vascular effects on ciliary tissue from endoscopic versus trans-scleral cyclophotocoagulation

AIM

To determine the acute and chronic vascular effects of endoscopic cyclophotocoagulation (ECP) versus trans-scleral cyclophotocoagulation (TCP) in a rabbit model.

METHODS

20 rabbits underwent ECP in one eye and another 20 rabbits had unilateral TCP. Five treated eyes from each group underwent endoscopic fluorescein angiography (EFA) of the treated ciliary processes at each of the following time points: immediate, 1 day, 1 week, and 1 month. Five untreated rabbits were used as controls. The NIH Image software program was used to trace ciliary processes in order to determine their mean intensity, as a measure of their perfusion. Histopathology was also performed on eyes from each time point.

RESULTS

Immediately and 1 day after laser, both TCP and ECP eyes demonstrated severely reduced or non-existent blood flow in the areas of treatment. TCP treated processes essentially remained non-perfused at the 1 week and 1 month time points. ECP treated processes showed some reperfusion at 1 week and greater reperfusion by 1 month. Histopathology confirmed the overall greater vascular occlusion seen with TCP.

CONCLUSIONS

Chronic poor perfusion of the ciliary body after TCP may account, in part, for its efficacy, as well as the significant complications including hypotony and phthisis. Late reperfusion of this region after ECP may provide some insight into the differences in efficacy and complication rates compared to TCP.

Correlation Between Intraocular Pressure, Central Corneal Thickness, Stage of Glaucoma, and Demographic Patient Data

PURPOSE

To determine the correlation of central corneal thickness (CCT) to Goldmann applanation tonometry (GAT) and dynamic contour tonometry (DCT, PASCAL), and to glaucoma stage as assessed by cup-to-disc ratio (CDR).

DESIGN

Prospective, cross-sectional tricenter observation study.

PATIENTS AND METHODS

From three glaucoma specialty practices a sample of 406 independent eyes was included. After ultrasound pachymetry, intraocular pressure was measured using PASCAL and Goldmann applanation tonometry and cup-to-disc ration was reassessed. Demographic data were included in the multivariate analysis.

RESULTS

Mean corneal thickness was 540 microm. African Americans and normal-tension glaucoma patients showed the lowest values (518 microm and 522 microm, respectively). These values were significantly thinner than the central corneal thickness of Caucasians (549 microm) and ocular hypertensives (564 microm). Intraocular pressure assessed by Goldmann applanation tonometry shows a significant correlation with central corneal thickness (r = 0.068, P < 0.001), whereas PASCAL is not significantly associated with central corneal thickness (r < 0.001, P = 0.997). Increased IOP is significantly correlated with large ocular pulse amplitudes (r = 0.13, P < 0.001), which is predominantly seen in ocular hypertensives. A significant negative correlation was detected between cup-to-disc ratio and central corneal thickness (r = 0.102, P < 0.001).

CONCLUSION

Glaucoma patients with thin central corneal thickness are more likely to be found at an advanced stage of the disease and among those with normal-tension glaucoma and black African ancestry. Underestimation of intraocular pressure by Goldmann applanation tonometry could be one causative factor.

Clinical Comparison of Contour and Applanation Tonometry and Their Relationship to Pachymetry

OBJECTIVES

To compare intraocular pressure readings of recently introduced dynamic contour tonometry (DCT) with pneumatonometry (PTG) and Goldmann applanation tonometry (GAT) and to correlate central corneal thickness (CCT) with these readings.

DESIGN

Prospective, cross-sectional observation and instrument validation study. We included 258 independent eyes with normal anterior segment examinations results, irrespective of glaucoma diagnosis or glaucoma suspect. After pachymetry, DCT, PTG, and GAT were performed in a randomized order. Intraocular pressures as measured by DCT, PTG, and GAT were compared with each other and with CCT.

RESULTS

Eyes with thinner CCTs tended to yield lower intraocular pressure measurements by GAT. A significant correlation (Pearson product moment correlation, P<.001) between CCT and GAT was found with a regression of 0.25 mm Hg per 10 microm (R2 = 0.060). Variation of CCT had no significant effect on intraocular pressure measurements by PTG (P = .10; R2 = 0.01) and DCT (P = .80; R2<0.01). A piecewise regression model showed that GAT readings are not linearly correlated with CCT. Comparison of the slopes below and above 535 microm showed the highest significance (P<.001).

CONCLUSIONS

Goldmann applanation tonometry readings are potentially influenced by CCT, whereas PTG and DCT seem to be less dependent on CCT. Correlation between CCT and GAT is not linear. A simple correction formula suggesting a linear relationship might not be correct.

Central corneal thickness of Caucasians, Chinese, Hispanics, Filipinos, African Americans, and Japanese in a glaucoma clinic

OBJECTIVE

To characterize the central corneal thickness (CCT) of Asian (Chinese, Japanese, and Filipino), Caucasian, Hispanic, and African American patients in a multiethnic glaucoma practice.

DESIGN

Retrospective study (chart review).

PARTICIPANTS

Glaucomatous (n = 600) and nonglaucomatous (n = 201) eyes of 801 patients examined in a San Francisco glaucoma clinic from June 2002 to April 2004 who met inclusion criteria were included in the study. The 6 racial (ethnic) groups represented in the study were Caucasian (n = 186, 23.2%), Chinese (n = 157, 19.6%), Japanese (n = 121, 15.1%), Hispanic (n = 116, 14.5%), Filipino (n = 114, 14.2%), and African American (n = 107, 13.4%).

METHODS

Central corneal thickness was measured by means of ultrasound pachymetry in Asian (Chinese, Japanese, and Filipino), Caucasian, Hispanic, and African American participants with glaucomatous and normal eyes. The relationship between CCT and race was investigated using multivariate regression analyses, controlling for confounders. One eye of each of 801 participants was included for analysis.

MAIN OUTCOME MEASURES

Correlation of mean CCT with race, glaucoma diagnosis, age, spherical equivalent, gender, and history of ocular surgery.

RESULTS

The mean CCT of all participants was 542.9 mum. Central corneal thicknesses of Chinese (555.6 microm), Caucasian (550.4 microm), Filipino (550.6 microm), and Hispanic (548.1 microm) participants did not significantly differ. The CCT of Japanese participants (531.7 microm) was significantly less than that of Caucasians, Chinese, Filipinos, and Hispanics (all, P< or =0.001) and greater than that of African Americans (P = 0.03). African Americans had a CCT (521.0.0 microm) less than that of all races (P< or =0.05). Glaucoma suspects and patients with normal tension glaucoma (NTG), primary open-angle glaucoma (POAG), pseudoexfoliation glaucoma (PEX), and chronic angle-closure glaucoma (CACG) had corneas significantly thinner than those of normal participants (P< or =0.004), whereas ocular hypertensives had significantly thicker corneas (P<0.0001). Among all participants, decreasing values of CCT were significantly related to older age (P<0.01). Less negative or more positive refractive errors, gender, and history of ocular surgery were not associated with changes in CCT (P = 0.38, P = 0.50, and P = 0.97, respectively).

CONCLUSIONS

Studies examining individual Asian subpopulations in isolation suggest that differences in CCT may exist among different Asian groups. The results of this study indicate that CCT does, in fact, vary among Asian subpopulations; Japanese have thinner corneas than Chinese and Filipinos. Caucasians, Chinese, Hispanics, and Filipinos have comparable CCT measurements, whereas the corneas of African Americans are significantly thinner. Additionally, older individuals; glaucoma suspects; and participants with NTG, POAG, PEX, and CACG have thinner corneas. Ocular hypertensives, however, have thicker corneas.

Accuracy of dynamic contour tonometry compared with applanation tonometry in human cadaver eyes of different hydration states

BACKGROUND

In an experimental laboratory investigation we compared intraocular pressure (IOP) measurements obtained by dynamic contour tonometry (DCT), Goldmann applanation tonometry (GAT), and pneumatonometry (PTG) with intracameral manometry on human cadaver corneas of different hydration conditions.

METHODS

Ten freshly enucleated eyes were de-epithelialized. Two tubes were placed in the anterior chamber in opposite directions and connected to a transducer and to a bottle system filled with balanced salt solution. The pressure in the eye was then adjusted between 5 mmHg and 58 mmHg by electronically altering the height of the bottle. Central corneal thickness (CCT) was registered and IOP measurements were obtained with DCT, GAT, and PTG at each manometric pressure reading. Immediately after the trial the same corneas were artificially dehydrated and the same measurement regimen was repeated.

RESULTS

In the pressure range defined by the bottle height 10-50 cm, IOP values measured by DCT were 0.50 mmHg (95% CI=0.40-0.60) and 0.36 mmHg (95% CI=0.25-0.47) higher than manometric readings before and after dehydration, respectively. GAT showed consistently lower values than manometry, the difference being -3.48 mmHg (95% CI=-3.91 to -3.05) and -3.14 mmHg (95% CI=-3.39 to -2.89), respectively. Similar results were obtained with PGT, namely differences of -4.75 mmHg (95% CI=-5.21 to -4.29) and -3.98 mmHg (95% CI=-4.48 to -3.48) for the hydrated and the dehydrated corneal condition, respectively. Only DCT showed no significant change in accuracy between hydrated and dehydrated corneas.

CONCLUSIONS

In this in vitro study DCT values for IOP were significantly closer to the manometric reference pressure than those obtained using GAT and PTG, independent of the state of corneal hydration.

Dynamic Contour Tonometry

OBJECTIVE

To compare intraocular pressure measurements obtained by recently introduced dynamic contour tonometry (DCT), Goldmann applanation tonometry (GAT), pneumatonometry (PTG), and intracameral manometry in human cadaver eyes.

METHODS

Sixteen freshly enucleated human cadaver eyes were deepithelialized and dehydrated with dextran. A tube was placed in the anterior chamber and connected to a transducer and to a bottle system filled with balanced salt solution. The pressure in the eye was then altered between 5 mm Hg and 58 mm Hg. Intraocular pressure measurements were obtained with DCT, GAT, and PTG at each manometric pressure reading.

RESULTS

On average, DCT values measured 0.58 +/- 0.70 mm Hg higher than real intracameral pressure. The GAT and PGT showed consistently lower values, -4.01 +/- 1.76 mm Hg and -5.09 +/- 2.61 mm Hg, respectively. At all bottle heights, DCT values were significantly closer to the reference pressure than GAT and PTG (P<.001).

CONCLUSIONS

Measurement with DCT provides IOP values significantly closer to true manometric levels than either GAT or PTG. Further studies are warranted to determine its reliability in patients and the effect of corneal thickness.

Visual acuity and its measurement

Despite its critical importance to our daily life, the most common measurement of visual function, visual acuity, is a relatively crude and narrow one testing only a small portion of the broad range of visual functions. Visual acuity is the measurement of the ability to discriminate two stimuli separated in space at high contrast relative to the background. Clinically, this is measured by asking the subject to discriminate letters of known visual angle. The visual acuity is represented as the reciprocal of the minimal angle of resolution (the smallest letters resolved) at a given distance and at high contrast. Other measurements of visual acuity also exist, including Vernier acuity. Newer charts, such as the ETDRS chart, use letters of equal recognition difficulty and use the log of the minimal angle of resolution; these charts have significant advantages over the old Snellen-type charts. This article reviews visual measurements in children and in patients with low vision, and it reviews factors affecting visual acuity, such as pupil size, refractive error, media opacities, and pharmacologic agents.

Enzymatic sclerostomy: pilot human study

OBJECTIVE

To evaluate the feasibility and safety of enzymatic sclerostomy as a new modality to lower intraocular pressure in patients with open-angle glaucoma.

METHODS

This single-center, prospective, noncomparative, interventional case series included 15 blind symptomatic eyes of 15 patients with primary open-angle glaucoma. Enzymatic sclerostomy was performed with the patient under topical or peribulbar anesthesia. A specially designed polymethylmethacrylate enzyme applicator filled with a mean +/- SD of 123 +/- 13 microg of collagenase was introduced through a 5-mm peritomy, and affixed to the limbus by means of cyanoacrylate tissue glue. After 22 to 24 hours, the applicators were removed and the patients were followed up for 1 year. Intraocular pressure changes from baseline and complications related to the procedure were the main outcome measures.

RESULTS

Controlled thinning of the treated sclera associated with aqueous percolation and shallow filtration bleb was seen in all eyes in the immediate postoperative period. The mean +/- SD intraocular pressure decreased from 43.5 +/- 9.8 mm Hg (while the patients were receiving a mean +/- SD of 1.75 +/- 0.75 antiglaucoma medications) preoperatively to 24.8 +/- 10.6 mm Hg (a 43.0% decrease from baseline with no antiglaucoma medication) on the first postoperative day and to 34.8 +/- 10.5 mm Hg (a 20.0% decrease from baseline with no antiglaucoma medication) at the end of 1 year. Ophthalmic adverse effects were limited to the treated area and included immediate postoperative transient conjunctival reaction ranging from mild chemosis to conjunctival maceration. Immediate full-thickness perforation developed in 1 eye; the patient was treated and excluded from data analysis. Two eyes developed symptoms related to increase in intraocular pressure after 9 months; the patients were treated and excluded from further data analysis. No systemic complications were noted.

CONCLUSIONS

Enzymatic sclerostomy demonstrated immediate and sustained intraocular pressure reduction and provided symptomatic relief in blind eyes with primary open-angle glaucoma. The procedure, however, needs further technical refinement.

Primary drug treatment for glaucoma: beta-blockers versus other medications

This set of Viewpoints articles examines the merits of beta-blockers versus other medications as the primary drug treatment for glaucoma. Ophthalmologists must balance issues such as efficacy, compliance, cost, and side effects when deciding on the appropriate medication to prescribe. Dr. Stamper stresses the advantages of tailoring the choice of medication to the needs of the individual patient. Drs. Wigginton and Higginbotham review the benefits of beta-blockers and present some of the disadvantages of the non-beta-blocker class of medications.

Presumed activation of herpetic keratouveitis after Argon laser peripheral iridotomy

PURPOSE

To describe presumed activation of herpetic keratouveitis after argon laser peripheral iridotomy.

METHOD

Case report.

RESULTS

A 68-year-old man developed chronic, unilateral, anterior uveitis associated with decreased corneal sensation, focal keratitis, and increased intraocular pressure after argon laser peripheral iridotomy. Treatment with oral acyclovir and discontinuation of topical latanoprost resulted in prompt and continued control of both the intraocular inflammation and pressure.

CONCLUSION

Herpetic keratouveitis may occur after argon laser iridotomy, and it should be considered when postoperative inflammation persists despite appropriate use of topical corticosteroids, particularly in patients with a history of herpetic eye disease.

Glaucoma screening using the scanning laser polarimeter

PURPOSE

To determine the ability of scanning laser polarimetry (GDx Nerve Fiber Analyzer; Laser Diagnostic Technologies, Inc., San Diego, CA) to separate normal eyes and those considered likely to have glaucoma in a public glaucoma screening.

METHODS

A 2-day public glaucoma screening program was held at two different institutions. Each subject underwent ophthalmologic examination, Humphrey perimetry (24-2 Fastpac program), and imaging using scanning laser polarimetry (GDx) in each eye for allocation into a diagnostic category: normal, ocular hypertensive, glaucoma suspect, or glaucoma. Results from the normal and glaucoma groups were analyzed, using modulation parameters calculated from a measurement band located 1.8 disc diameters from the disc, and selected parameters provided automatically by GDx software. Receiver operating characteristic curves were used to depict the sensitivity/specificity relationship at different GDx parameter cutoff levels.

RESULTS

Of 200 subjects, 197 were classified; 122 were classified as normal, 23 were classified with ocular hypertension, 30 were classified as glaucoma suspects, and 22 were classified with definite glaucoma. Three subjects had ocular diseases other than glaucoma. The maximum area under the receiver operating characteristic curve for modulation parameters was 0.935, and for the GDx software parameters was 0.901.

CONCLUSIONS

Scanning laser polarimetry may be useful in glaucoma screening.

Screening for glaucoma with frequency-doubling technology and Damato campimetry

OBJECTIVE

To assess frequency-doubling technology (FDT) perimetry (Humphrey Systems, San Leandro, Calif) and Damato campimetry (Precision Vision, Villa Park, Ill) for detecting glaucoma in a public glaucoma screening.

METHODS

A 2-day public glaucoma screening was held at 2 different institutions. Each subject underwent 2 visual field screening tests (Damato campimetry and FDT perimetry in screening mode), an ophthalmologic examination, and Humphrey perimetry (24-2 FASTPAC) for each eye. Eyes were divided into 4 categories: normal, ocular hypertensive, glaucoma suspect, and definite glaucoma. The sensitivity and specificity of FDT perimetry and Damato campimetry for detecting glaucoma were estimated with receiver operating characteristic curves.

RESULTS

Among 240 subjects who underwent FDT, the number identified as normal, ocular hypertensive, glaucoma suspect, and definite glaucoma was 151, 28, 35, and 26, respectively; among 175 subjects who underwent Damato campimetry, the numbers for the same groups were 118, 19, 19, and 19, respectively. The areas under the receiver operating characteristic curve for FDT perimetry and Damato campimetry were 0.925 and 0.883, respectively. The optimal sensitivity and specificity for FDT perimetry were 92% and 93%, while those for Damato campimetry were 53% and 90%, respectively. The average test time was 1 minute and 3 minutes per eye for FDT perimetry and Damato campimetry, respectively.

CONCLUSION

Frequency-doubling technology perimetry was superior to Damato campimetry in this screening for glaucoma.

Late onset of sequential multifocal bleb leaks after glaucoma filtration surgery with 5-fluorouracil and mitomycin C

PURPOSE

To describe the late onset of sequential multifocal bleb leaks as a postoperative complication after filtering surgery with antimetabolites.

MATERIALS

Retrospectively, 385 consecutive eyes (304 patients) undergoing trabeculectomy with 5-flurouracil (5-FU) or mitomycin C (MMC) from 1989 to 1994 were reviewed. Eyes with filtration bleb leak occurring 6 months or more after trabeculectomy were analyzed, and clinical characteristics of the filtration bleb, response to treatment, and bleb histopathology from eyes undergoing bleb excision were analyzed.

RESULTS

In seven (1.8%) of 385 consecutive eyes from 304 patients undergoing glaucoma filtration surgery with 5-FU or MMC, repetitive bleb leaks in different locations of the bleb were observed from 9 to 44 months (mean, 20.4 months) after the procedure. One hundred ninety-three eyes (50%) were treated with 5-FU and the remaining eyes, with MMC. All eyes had transparent, avascular, lobular, cystic blebs. Bleb leaks occurred in five eyes treated postoperatively with subconjunctival 5-FU and in two eyes in which MMC was used intraoperatively. Three eyes (all treated with 5-FU) required surgical excision, and four eyes healed with soft contact lens, cyanoacrylate glue, or intrableb injection of autologous blood. Histopathology of the bleb leak sites demonstrated focal epithelial thinning and interruption with subjacent hypocellularity and stromal collagen degeneration.

CONCLUSION

Late sequential multifocal bleb leaks may occur after glaucoma filtration surgery with administration of antimetabolites (5-FU or MMC) and are associated with epithelial break-down, hypocellularity, and stromal collagen necrosis in the filtration bleb.

Midterm follow-up results of combined phacoemulsification, lens implantation, and mitomycin-C trabeculectomy procedure

PURPOSE

This study evaluates the visual, refractive, perimetric, and intraocular pressure (IOP) results following combined phacoemulsification, lens implantation, and trabeculectomy with mitomycin-C.

METHODS

Twenty-nine consecutive eyes of 26 patients with cataract and glaucoma that had undergone combined phacoemulsification, posterior chamber lens implantation, and limbus-based trabeculectomy with mitomycin-C applied after the cataract removal and trabeculectomy had a minimal follow-up time of 12 months (mean follow-up 20 +/- 6.3 months). Each eye was evaluated for visual acuity, corneal astigmatism, IOP, bleb persistence, optic nerve stability, visual field status, and complications. Goldmann visual fields were assessed by a semi-quantitative method and threshold static perimetry by statistical indices of diffuse damage (mean deviation) and focal loss (corrected pattern standard deviation). The preoperative and postoperative results were compared by Student's t-test.

RESULTS

All eyes that were free of pre-existing macular disease demonstrated significant improvement in visual acuity by at least 4.5 lines of Snellen acuity. Postoperative astigmatism was negligible (0.29 diopters). The average IOP reduction was 6.5 mm Hg, with the one year or more average of 13.4 mm Hg on virtually no antiglaucoma medicines (0.2 +/- 0.5). Functioning filtering blebs persisted in 86% of eyes. Of 11 patients tested with pre- and postoperative Goldmann perimetry, only two showed visual field defect progression despite IOPs < 15 mm Hg. Of the 12 eyes with pre- and postoperative static threshold perimetry, the mean deviation deteriorated in nine eyes (p = 0.003). The corrected pattern standard deviation changes were not statistically significant (p = 0.69). Complications (including two cases of late-onset endophthalmitis) were comparable with other studies reporting filtration surgery with adjunctive antimetabolites. We detected no untoward effects of applying the mitomycin at the end of the procedure rather than at the beginning.

CONCLUSIONS

The combined procedure technique that we describe appears to be effective at restoring visual acuity and significantly reducing IOP. Nevertheless, many visual fields showed continued, diffuse glaucomatous progression in the year or two following surgery and the development of late endophthalmitis in two eyes is a concern.

Interobserver and intraobserver variability in the detection of glaucomatous progression of the optic disc

PURPOSE

To evaluate the potential value of obtaining follow-up stereoscopic photographs on glaucoma suspects in identifying progressive optic nerve damage.

METHODS

Nineteen sets of stereoscopic optic disc photographs, reflecting one eye from each of 19 patients at two time points, were selected from the records of subjects enrolled in the Glaucoma Screening Study. By consensus, three experts judged 13 of these eyes to have progressive glaucomatous optic nerve damage. Four other ophthalmologists who were masked to the expert panel evaluation then assessed glaucomatous progression in the same eyes. They were asked to evaluate glaucomatous progression in three ways: first, by drawing the optic nerve head appearance from initial stereoscopic photographs and later comparing their own drawings to follow-up stereoscopic photographs; second, by comparing serial stereoscopic photographs directly; and third, by comparing drawings of the optic nerve head made by another examiner to the follow-up photographs.

RESULTS

Neither sensitivity nor specificity was consistently better for serial stereoscopic photographs than for drawings. Individual ophthalmologist agreement rates with the expert panel's determinations of progression were 23-62% when examiners compared their own drawings to follow-up photographs, 54-71% when examiners compared serial stereoscopic photographs, and 38-85% when comparing another ophthalmologist's drawings to follow-up photographs.

CONCLUSION

Baseline stereoscopic photographs of the optic nerve head did not substantially improve recognition of progressive glaucomatous optic nerve damage when compared with the use of baseline drawings of the optic nerve head made from photographs in subjects who developed visual loss in the interim.

Evaluation of optic disc measurements with the glaucoma-scope

PURPOSE

We evaluated the Glaucoma-Scope's ability to acquire images of the optic disc, the reproducibility of its analysis, and the comparison between it and expert evaluation.

METHODS

One hundred and sixty-eight patients with satisfactory standard fundus photography were referred for Glaucoma-Scope analysis. Characteristics of eyes in which Glaucoma-Scope analysis could not be obtained were evaluated. Eight glaucoma patients (15 eyes) were quantitatively evaluated: inter- and intraobserver reproducibility of the Glaucoma-Scope analyses were calculated utilizing weighted Kappa index of agreement and coefficient of variation. The Glaucoma-Scope cup-to-disc ratio was calculated from the gray scale analysis and compared to the ratio as evaluated by a glaucoma expert.

RESULTS

Glaucoma-Scope analysis was not achieved in 14% of a total of 336 eyes of 168 patients. The conditions associated with the inability to obtain a satisfactory image were hyperpigmented fundi, pseudophakia, aphakia, corneal opacities, cataract, and contact lenses. The quantitative analysis of the 15 patients showed small inter- and intraobserver means of the coefficient of variation (0.136 +/- 0.023 and 0.129 +/- 0.016) and SD (0.063 +/- 0.0056 and 0.064 +/- 0.0077) and moderate-substantial intra- and interobserver agreement (weighted K = 0.427 +/- 0.1 and 0.61 +/- 0.14, respectively). Significant disagreement (weighted K = -0.11, p = 0.0023) was found between Glaucoma-Scope (mean 0.52 +/- 0.064) and expert's evaluations (0.673) of the cup-to-disc ratio.

CONCLUSIONS

The inter- and intraobserver reliability and low variation of the Glaucoma-Scope readings indicates moderate to substantial reproducibility for detecting changes in optic disc's topography under selected conditions. However, eyes with moderate cataract, aphakia, pseudophakia, mild corneal opacity, darkly pigmented fundi or myopia were inconsistently analyzable. In a small group of randomly selected eyes there was very low agreement between the glaucoma expert's evaluation of the optic disc and that of the Glaucoma-Scope. These findings raise questions about the usefulness of the instrument as a diagnostic tool for glaucoma but show promise for detecting change when good images are possible.

The temporal visuogram in ocular hypertension and its progression to glaucoma

In a study of progression to glaucoma in ocular hypertensive eyes followed for at least 4 years, temporal flicker sensitivity measured at the beginning of the period was evaluated as a predictor of the likelihood of progression. Significantly abnormal temporal visuograms at a 1 criterion predicted progression in 9 of 10 eyes that developed glaucomatous losses. Temporal visuograms for locations in the nasal arcuate area (15 nasal to fixation) showed much greater sensitivity to visual loss than those in the central part of the retina. Comparison with threshold perimetry losses showed that patients within the normal range on the central four points were also within normal range on the temporal visuogram. Peripheral flicker testing was more sensitive than threshold perimetry to losses in the nasal arcuate area in glaucoma patients.

Brimonidine in the prevention of intraocular pressure elevation following argon laser trabeculoplasty

OBJECTIVE

To evaluate the efficacy of 0.5% brimonidine tartrate, an alpha 2-adrenergic agonist, in preventing intraocular pressure (IOP) elevation following argon laser trabeculoplasty.

DESIGN

In a multicenter, double-masked, randomized study, 248 patients (248 eyes) who underwent argon laser trabeculoplasty were allocated to four treatment groups: (1) brimonidine administered before and after the procedure; (2) brimonidine administered before the procedure; (3) brimonidine administered after the procedure; and (4) a vehicle administered before and after the procedure.

RESULTS

In the first 3 hours after argon laser trabeculoplasty, only one (0.54%) of the 183 brimonidine-treated patients had a postlaser IOP increase of 10 mm Hg or more, while increases of this magnitude occurred in 13 (23%) of the 56 patients who received only the vehicle (P < .001). The three brimonidine-treatment groups demonstrated significant mean reductions in IOP from the pretrabeculoplasty level (-4 to -8 mm Hg), whereas the vehicle-treated group showed an increase in mean IOP (4 mm Hg). Side effects associated with brimonidine treatment included conjunctival blanching (40.9%), lid retraction (7.6%), and a slight lowering of the systolic blood pressure.

CONCLUSIONS

One drop of 0.5% brimonidine administered either before or after surgery was found to be efficacious and safe in preventing posttrabeculoplasty elevations in IOP.

Long-term effects of mitomycin on filtering blebs. Lack of fibrovascular proliferative response following severe inflammation

BACKGROUND AND OBJECTIVE

The use of antimetabolites, such as fluorouracil and mitomycin, enhances the success rate of filtering surgery, especially in eyes at high risk for failure, and increases the likelihood of a thin, avascular filtering bleb. In addition, mitomycin may cause long-term inhibition of the fibroblast's ability to proliferate in the conjunctiva and Tenon's capsule. Preoperative and postoperative inflammation frequently contributes to scarring of filtering blebs. The purpose of this study is to evaluate the effect of intraoperative mitomycin use on the survival of filtering blebs after severe inflammation.

DESIGN

We retrospectively studied three eyes that had undergone trabeculectomy with intraoperative mitomycin. Two eyes had concomitant intraocular lens implantation. All three eyes had blebs that functioned well postoperatively.

PATIENTS

These eyes sustained episodes of intense inflammation in the form of herpes zoster ophthalmicus, endophthalmitis, or purulent infection of the bleb postoperatively.

RESULTS

Following treatment of the inflammation, no change in the appearance or function of the bleb could be detected.

CONCLUSION

Either the indirect effect of mitomycin in producing a thin, avascular bleb or a long-term effect of mitomycin on the ability of conjunctival and Tenon's capsule fibroblasts to proliferate may have contributed to bleb survival.

Intraocular pressure and corneal curvature changes on application of limbal-scleral suction fixation ring in rabbits

Suction rings are used to stabilize the globe during refractive surgery procedures. This study investigates the changes in ocular pressure and corneal curvature induced by a suction ring on rabbit corneas. A sharp rise in intraocular pressure, to as high as 80 mm Hg, followed by a time-dependent decline was found. The application of this ring also caused astigmatic changes in the cornea. Corneal thickening was also encountered. These findings have implications for possible artifactual changes during photorefractive keratoplasty and raise the possibility of intraocular pressure-induced damage in susceptible individuals.

Hypotonous maculopathy after trabeculectomy with subconjunctival 5-fluorouracil

Long-term success in trabeculectomy has been enhanced in recent years by postoperative subconjunctival 5-fluorouracil injections and intraoperative mitomycin C applications. During 1990 and 1991, after trabeculectomy with a small scleral flap (2 x 3 mm) augmented by antimetabolite therapy, hypotonous maculopathy developed in eight eyes of six patients. The maculopathy was characterized by loss in visual acuity, retinal striae, and choroidal folds without evidence of vascular leakage. The average loss in visual acuity was four Snellen lines. Visual acuity did not return to preoperative levels even when the hypotony could be reversed. Reversing the hypotony with various strategies aimed at stimulating subconjunctival scarring has been relatively ineffective. During that same period, an additional seven eyes in six patients had prolonged hypotony but without development of maculopathy. Features common to patients who developed maculopathy included age (mean age, 46 years; range, 32 to 60 years) and myopia (mean, -7.5 diopters; range, -0.75 to -11.75 diopters). The patients with hypotony but no maculopathy were older (mean age, 73 years; range, 63 to 82 years) and were closer to emmetropia (mean, -1.11 diopters; range, +1.50 to -9.00 diopters). The means of the ages and refractive errors were statistically significantly different in the two groups (P = .007 and .04, respectively). Trabeculectomy with adjunctive antifibrosis therapy should be used with caution in young myopic patients.

Acute ptosis secondary to contact lens wear

Ocular ptosis secondary to the wearing of rigid contact lenses has been reported. Generally this ptosis is not of the classical variety, and appears to be an edematous or inflammatory response of the lid to the presence of the lens. We report a case of acute ptosis secondary to rigid lens wear in a patient who had undergone cataract surgery. The patient had been a contact lens wearer before surgery, and developed the relative ptosis postsurgically in the nonoperated eye. The ptosis resolved without any form of intervention other than ceasing to wear the contact lens. We feel that in cases where rigid lens wear is discontinued unilaterally for any reason, and a relative ptosis is noted, it should be given time to resolve before any therapeutic regimen is considered.