Clinical classification of glaucomatous visual field loss by frequency doubling perimetry

Long-term Outcomes in Patients Undergoing Surgery for Primary Congenital Glaucoma between 1991 and 2000: A Single-Center Database Study

PURPOSE

To estimate the long-term surgical and visual outcomes in patients with primary congenital glaucoma (PCG) who completed at least 20 years of follow-up.

DESIGN

Retrospective study.

PARTICIPANTS

Two hundred twenty eyes of 121 patients undergoing surgery for PCG between January 1991 and December 2000 and who returned for a follow-up visit from January 2021 through January 2022.

METHODS

Retrospective review of medical records of patients who underwent primary combined trabeculotomy-trabeculectomy (CTT) without mitomycin C as an initial procedure. Success was defined as complete when intraocular pressure (IOP) was ≥ 6 mmHg and ≤ 21 mmHg without glaucoma medication and as qualified when up to 2 glaucoma medications were required. Failure was defined as uncontrolled IOP with more than 2 glaucoma medications, need for a second IOP-lowering procedure, chronic hypotony (IOP < 6 mmHg on 2 consecutive visits), or any sight-threatening complication. A mixed-effects model using maximum likelihood estimation was used in estimation of eye-based variables and to make comparisons between different visits. Kaplan-Meier survival analysis was used to estimate the probabilities of surgical and functional successes. Cox proportional hazards regression using sandwich clustered estimation was used to evaluate risk factors for failure and poor visual outcome.

MAIN OUTCOME MEASURES

Primary outcome measure was the proportion of patients who demonstrated complete success over the 20-year follow-up. Secondary outcome measures included rate of surgical failure and need for reoperation for glaucoma, visual acuity, refractive errors, risk factors for poor outcome, and complications.

RESULTS

Kaplan-Meier survival analysis revealed 1-year, 10-year, and 20-year complete success rates of 90.7%, 78.9%, and 44.5%, respectively. In univariate analysis, surgical failure was higher among patients with any additional non-glaucoma intraocular surgery. None of the clinical parameters were associated significantly with failure in multivariable analysis. Overall, the proportion of eyes with good, fair, and poor visual outcomes was 33.2%, 16.4%, and 50.4%, respectively. Myopia was seen in 68.9% eyes. Twenty-eight eyes of those who underwent primary CTT (14.4%) required second surgery for IOP control. No significant intraoperative complications occurred. Six eyes required enucleation because of painful blind eye.

CONCLUSIONS

In this large cohort of patients with PCG, CTT is a useful procedure. It provides good IOP control and moderate visual recovery that remained over a 20-year follow-up after surgery.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Structural Analysis of Glaucoma Brain and its Association With Ocular Parameters

PRECIS

Glaucoma patients presented a decreased occipital pole surface area in both hemispheres. Moreover, these parameters are independently correlated with functional and structural ocular parameters.

PURPOSE

The purpose of this study was to evaluate structural brain abnormalities in glaucoma patients using 3-Tesla magnetic resonance imaging and assess their correlation with associated structural and functional ocular findings.

PATIENTS AND METHODS

This cross-sectional prospective study included 30 glaucoma patients and 18 healthy volunteers. All participants underwent standard automated perimetry, spectral-domain optical coherence tomography, and 3.0-Tesla magnetic resonance imaging.

RESULTS

There was a significant difference between the surface area of the occipital pole in the left hemisphere of glaucoma patients (mean: 1253.9±149.3 mm) and that of control subjects (mean: 1341.9±129.8 mm), P=0.043. There was also a significant difference between the surface area of the occipital pole in the right hemisphere of glaucoma patients (mean: 1910.5±309.4 mm) and that of control subjects (mean: 2089.1±164.2 mm), P=0.029. There was no significant difference between the lingual, calcarine, superior frontal, and inferior frontal gyri of glaucoma patients and those of the control subjects (P>0.05 for all comparisons). The surface area of the occipital pole in the left hemisphere was significantly correlated with perimetry mean deviation values, visual acuity, age, and retinal nerve fiber layer thickness (P=0.001, <0.001, 0.010, and 0.006, respectively). The surface area of the occipital pole in the right hemisphere was significantly correlated with perimetry mean deviation values, visual field indices, visual acuity, age, and retinal nerve fiber layer thickness (P<0.001, 0.007, <0.001, 0.046, and <0.001, respectively).

CONCLUSION

Glaucoma patients presented a decreased occipital pole surface area in both hemispheres that independently correlated with functional and structural ocular parameters.

Evidence-based understanding of disc hemorrhage in glaucoma

Disc hemorrhage is a characteristic finding that is highly associated with glaucoma development or progression. Consequently, the literature commonly designates disc hemorrhage as a "risk factor" for glaucoma progression; however, the exact cause-and-effect relationship or mechanism remains unclear. In this review, we discuss the emerging evidence that disc hemorrhage is a secondary development that follows glaucomatous damage. As our understanding of disc hemorrhage has progressed in recent decades, we suggest the terminology be changed from "risk factor" to "indicator" of ongoing glaucomatous development or progression for a more accurate description, better indication of the clinical implications and, ultimately, a better guide for future research.

Refined Frequency Doubling Perimetry Analysis Reaffirms Central Nervous System Control of Chronic Glaucomatous Neurodegeneration

PURPOSE

Refined analysis of frequency doubling perimetric data was performed to assess binocular visual field conservation in patients with comparable degrees of bilateral glaucomatous damage, to determine whether unilateral visual field loss is random, anatomically symmetric, or non-random in relation to the fellow eye.

METHODS

Case control study of 41 consecutive patients with bilaterally mild to severe glaucoma; each right eye visual field locus was paired with randomly-selected co-isopteric left eye loci, performing 690,000 (10,000 complete sets of 69 loci) such iterations per subject. The potential role of anatomic symmetry in bilateral visual field conservation was also assessed by pairing mirror-image loci of the right- and left-eye fields. The mean values of the random co-isopteric and the symmetric mirror pairings were compared with natural point-for-point pairings of the two eyes by paired t-test.

RESULTS

Mean unilateral Matrix threshold across the entire 30-degree visual field were 17.0 dB left and 18.4 dB right (average 17.7). The better of the naturally paired concomitant loci yielded binocular equivalent mean bilateral Matrix threshold of 20.9 dB, 1.6 dB higher than the population mean of the 690,000 coisopteric pairings (t = -10.4; P < 10^-12). Thus, a remarkable natural tendency for conservation of the binocular Matrix visual field was confirmed, far stronger than explicable by random chance. Symmetric pairings of precise mirror-image loci also produced values higher than random co-isopteric pairings (Δ 1.1 dB; t = -4.0; P = 0.0004).

CONCLUSIONS

Refined data analysis of paired Matrix visual fields confirms the existence of a natural optimization of binocular visual function in severe bilateral glaucoma via interlocking fields that could only be created by CNS involvement. The disparity of paired Matrix threshold values at mirror-image loci was also highly nonrandom and quantitatively inverse from the expected if anatomic symmetry factors were merely passively contributing systematically to the compensatory binocular Matrix effect.

TRANSLATIONAL RELEVANCE

The paired eyes and brain are reaffirmed to function as a unified system in the progressive age-related neurodegenerative condition chronic open angle glaucoma, maximizing the binocular visual field. Given the extensive homology of this disorder with other age-related neurodegenerations, it is reasonable to assume that the brain will similarly resist simultaneous bilateral loss of paired functional zones in both hemispheres in diseases like Alzheimer's and Parkinson's disease. Glaucomatous eyes at all stages of the disease appear to provide a highly accessible paired-organ study model for developing therapeutics to optimize conservation of function in neurodegenerative disorders.

Frequency-doubling technology perimetry and multifocal visual evoked potential in glaucoma, suspected glaucoma, and control patients

INTRODUCTION

The gold standard in functional glaucoma evaluation is standard automated perimetry (SAP). However, SAP depends on the reliability of the patients' responses and other external factors; therefore, other technologies have been developed for earlier detection of visual field changes in glaucoma patients. The frequency-doubling perimetry (FDT) is believed to detect glaucoma earlier than SAP. The multifocal visual evoked potential (mfVEP) is an objective test for functional evaluation.

OBJECTIVE

To evaluate the sensitivity and specificity of FDT and mfVEP tests in normal, suspect, and glaucomatous eyes and compare the monocular and interocular mfVEP.

METHODS

Ninety-five eyes from 95 individuals (23 controls, 33 glaucoma suspects, 39 glaucomatous) were enrolled. All participants underwent a full ophthalmic examination, followed by SAP, FDT, and mfVEP tests.

RESULTS

The area under the curve for mean deviation and pattern standard deviation were 0.756 and 0.761, respectively, for FDT, 0.564 and 0.512 for signal and alpha for interocular mfVEP, and 0.568 and 0.538 for signal and alpha for monocular mfVEP. This difference between monocular and interocular mfVEP was not significant.

CONCLUSION

The FDT Matrix was superior to mfVEP in glaucoma detection. The difference between monocular and interocular mfVEP in the diagnosis of glaucoma was not significant.

Refined Data Analysis Provides Clinical Evidence for Central Nervous System Control of Chronic Glaucomatous Neurodegeneration

PURPOSE

Refined data analysis was performed to assess binocular visual field conservation in patients with bilateral glaucomatous damage to determine whether unilateral visual field loss is random, anatomically symmetric, or nonrandom in relation to the fellow eye.

METHODS

This was a case-control study of 47 consecutive patients with bilaterally severe glaucoma; each right eye visual field locus was paired with randomly selected coisopteric left eye loci, with 760,000 (10,000 complete sets of 76 loci) such iterations performed per subject. The potential role of anatomic symmetry in bilateral visual field conservation was also assessed by pairing mirror-image loci of the paired fields. The mean values of the random coisopteric and the symmetric mirror pairings were compared with natural point-for-point pairings of the two eyes by paired t-test.

RESULTS

Mean unilateral thresholds across the entire visual field were 18.9 dB left and 19.9 dB right (average 19.4), 4 dB lower than the better of the naturally paired concomitant loci of 23.4 dB (P < 10^-15). A remarkable natural tendency for conservation of the binocular visual field was confirmed, far stronger than explicable by random chance or anatomic symmetry (P < 0.0001), and reaffirmed by subsequent prospective simultaneous binocular visual field retesting of an arbitrary subset (n = 16) of the study population (P < 0.0001).

CONCLUSIONS

Refined data analysis of paired visual fields confirms the existence of a natural optimization of binocular visual function in severe bilateral glaucoma via interlocking fields that could be created only by central nervous system (CNS) involvement.

TRANSLATIONAL RELEVANCE

Integrated bilateral visual field analysis should better define actual visual disability and more accurately reflect the functional efficacy of current ocular and future CNS-oriented therapeutic approaches to the treatment of glaucoma. Glaucomatous eyes provide a highly accessible paired-organ study model for developing therapeutics to optimize conservation of function in neurodegenerative disorders.

Anatomic and functional correlation of frequency-doubling technology perimetry (FDTP) in multiple sclerosis

To study the correlation between the results of frequency-doubling technology perimetry (FDTP), visual function (visual acuity, contrast vision, standard automated perimetry (SAP)) and the thickness of the retinal nerve fiber layer (RNFL) throughout the course of multiple sclerosis (MS). Sixty-six eyes of thirty-three patients suffering from MS were chosen. Thirty-five eyes had a previous history of optic neuritis (ON group) and thirty-one eyes had no previous history of optic neuritis (non-ON group). The FDTP was performed with the N-30 screening program. Visual acuity was determined with the Snellen scale and the ETDRS (Early Treatment Diabetic Retinopathy Study) scale, the contrast vision with the Pelli-Robson and Sloan tests and the SAP with the Humphrey 750 perimeter. The thickness of the RNFL was measured using the STRATUS OCT™ optical coherence tomography (OCT). The visual field FDTP was divided into three sectors corresponding to the three SAP sectors and to the three RNFL quadrants of the OCT. The FDTP was significantly correlated (P<0.0001) to the contrast vision and to the SAP results (mean deviation (MD) and the different sectors among themselves). In the ON group, the MD FDTP was significantly correlated to the average RNFL thickness (r=0.44, P=0.0091). A decrease of 5 decibels (dB) of the MD FDTP corresponded to a decrease of 11.7 μm of the average RNFL thickness (Y=2.34×X+87.5). The strong correlation with SAP and RNFL confirms the value of FDTP in assessing optic nerve damage throughout the course of MS.

Retinal nerve fiber layer thickness and spatial and temporal contrast sensitivity in multiple sclerosis

PURPOSE

To measure peripapillary retinal nerve fiber layer (RNFL) thickness and spatial and temporal contrast sensitivity in multiple sclerosis (MS) taking into account previous history of optic neuropathy (ON).

METHODS

Thirty patients (60 eyes) with relapsing-remitting MS were selected (MS group). The MS ON group was composed of 31 eyes with previous history of optic neuropathy and the MS non-ON group of 29 eyes was without previous history of optic neuropathy. Thickness of the RNFL was measured with optical coherence tomography (OCT) with the Stratus OCT. As for sensitivity to spatial contrast,we used Pelli-Robson and Sloan charts. Sensitivity to temporal contrast was explored using frequency doubling technology perimetry (FDTP).

RESULTS

The average thickness of RNFL in the MS, MS ON, MS non-ON, and control groups were 88.2 +/= 18.9 microm, 80.81 +/- 18.4 microm, 96.7 +/- 15.8 microm, and 106 +/- 12.2 microm, respectively. The spatial contrast vision and FDTP results were less in the MS non-ON group than in the control group. The average thickness of RNFL correlated to the scores of spatial and temporal contrast vision.

CONCLUSIONS

MS is accompanied by visual function alteration even in the absence of acute optic neuropathy. The important correlation between functional and anatomic aspect confirms the value of OCT to appreciate the subclinical involvement of the optic nerve. Associated with tests exploring visual function, the OCT could reveal itself pertinent in evaluation of the different therapeutics used in MS ON.

Glaucoma diagnostic performance of humphrey matrix and standard automated perimetry

PURPOSE

To evaluate and compare the performance of Humphrey Matrix perimetry (Matrix) and standard automated perimetry (SAP) for glaucoma discrimination.

METHODS

Forty-seven healthy and 68 glaucomatous subjects were included in this study. Glaucoma was defined as having a glaucomatous optic disc and a nerve fiber indicator (NFI) GDx VCC scanning laser polarimetry score of >40. Glaucomatous subjects were classified into two groups, early (40 < NFI < or = 50) and moderate to advanced (NFI > 50). The number of clusters on Matrix and SAP pattern deviation maps were estimated and scored. Areas under the receiver operating characteristic curves (AUCs) of the cluster scores were calculated for early and moderate to advanced stages of glaucoma and compared between Matrix and SAP.

RESULTS

Among 68 glaucomatous subjects, 24 eyes were classified as having early and 44 eyes as having moderate to advanced glaucoma. The overall AUC of the Matrix cluster score was comparable to that of SAP (0.857, 0.881, P = 0.538). The AUC of the cluster score did not reveal statistically significant differences between Matrix and SAP for either early or moderate to advanced stages of glaucoma (P = 0.831, 0.237).

CONCLUSION

Both Matrix and SAP showed good diagnostic performance with glaucoma defined as structural loss. Matrix and SAP data showed similar discrimination capability for different stages of glaucoma determined by cluster analysis.

Structural and functional relationships in glaucoma using standard automated perimetry and the Humphrey Matrix

Purpose

To evaluate and compare correlations between structural and functional loss in glaucoma as assessed by optical coherence tomography (OCT), scanning laser polarimetry (GDx VCC, as this was the model used in this study), standard automated perimetry (SAP), and the Humphrey Matrix (Matrix).

Methods

Ninety glaucomatous eyes identified with SAP and 112 eyes diagnosed using Matrix were independently classified into six subgroups, either S1/M1 (MD>-6dB), S2/M2 (-12<MD<-6dB) or S3/M3 (MD<-12dB), according to the mean deviation (MD) of each test. Average and sectoral retinal nerve fiber layer (RNFL) thickness and percentage of abnormal classifications using the internal normative databases of OCT and GDx VCC were compared among the six subgroups.

Results

In the SAP subgroups, RNFL thickness values obtained by OCT in the nasal and temporal quadrants and the inferior averages of GDx VCC did not differ between the S1 and S2 subgroups (p=0.137, 0.738 and 0.149, respectively). In the Matrix subgroups, no measurement parameters differed between the M1 and M2 groups except for the overall mean and average inferior RNFL thickness given by OCT and the NFI values of GDx VCC (p=0.013, 0.016 and 0.029, respectively). When abnormal classifications were compared, all measurement parameters, without exception, were significantly different in both the SAP and the Matrix subgroups.

Conclusions

SAP subgroups showed a good correlation of structural and functional defects when assessed using OCT and GDx VCC. These correlations were weaker in the Matrix subgroups, especially in the early stages of glaucoma.

Frequency doubling technology threshold visual field results vary with software version

PURPOSE

To determine the comparability of test results obtained using two versions of commercially available frequency doubling technology (FDT) software for visual field testing.

METHODS

One hundred glaucoma patients underwent duplicate N-30 threshold FDT visual field examinations of one eye; one test was performed with the recently released software version 3.0 and the other test with the earlier version 2.6. Results were compared in terms of test duration, mean deviation (MD), pointwise sensitivity, pointwise deviations from the age-normal threshold, and average sensitivity.

RESULTS

Results obtained with version 3.0 differed significantly from those obtained with version 2.6. Version 3.0 tests took on average 14.2% less time (P < 0.0001), and the average MD was 0.53 dB more negative (P < 0.01). Version 3.0 threshold estimates derived from a mixed-model analysis were significantly lower at 15 of 19 test points (P = 0.0074). At 14 of the 19 test point locations, the mixed-model analysis also showed that threshold measurements were more frequently outside the normal range with version 3.0 (P = 0.022).

CONCLUSIONS

We found statistically significant differences between results obtained using FDT versions 3.0 and 2.6, which might affect clinical management. New age-corrected normal values for version 3.0 should be obtained and made available to users, and new baseline field data should be established whenever a patient is switched from version 2.6 to version 3.0.

Sector-based analysis of frequency doubling technology sensitivity and optic nerve head shape parameters

PURPOSE

To evaluate which Heidelberg Retina Tomograph (HRT) parameter is the best predictor of frequency doubling technology (FDT) sensitivity by using a sector based analysis between FDT and optic nerve head shape parameters such as cup shape measure (CSM) and rim area (RA), which have been shown to have the best correlation with FDT indices among all the HRT parameters.

METHODS

One eye was randomly chosen from 100 patients with primary open angle glaucoma (abnormal visual field and/or abnormal optic nerve and untreated intraocular pressure above 21 mm Hg). All the patients were examined with Humphrey field analyzer (HFA), program 24-2, SITA standard, FDT program C 20, and HRT. RA and CSM for the HRT analysis and mean deviation, pattern standard deviation, and the sensitivity of each tested point for the FDT test were considered in this study. All the parameters were calculated as both global and sector measurements. Findings were analyzed using Pearson's correlation coefficient and linear regression model.

RESULTS

Significant (p<0.001) correlation was found between FDT indices and HRT RA and CSM. Significant (p<0.001) sector correlation was found between FDT sensitivity and RA and CSM, but when a linear regression model was applied, RA was the most predictive parameter of FDT. Temporal CSM was more strongly correlated to FDT fovea sensitivity than temporal RA. Furthermore, sector HRT parameters were better correlated to HFA than to FDT.

CONCLUSIONS

In this glaucomatous group, cup shape measure and RA were significantly correlated to FDT indices. RA was more predictive of FDT abnormality than CSM in all the considered sectors except in the temporal one. However, HFA was a stronger predictor of HRT parameters than FDT.

The loss of visual function in glaucoma

This article reviews innovative techniques for assessing the visual field and for examining glaucoma patients for evidence of visual field progression. The authors discuss the algorithms for assessing change in visual fields used in each of several multicenter studies sponsored by the National Eye Institute. The authors also give a brief review of 2 currently available alternatives to standard automated perimetry. Both are visual function specific tests that attempt to evaluate a subpopulation of retinal ganglion cells. Shortwavelength automated perimetry isolates the small bistratified (blue-yellow) ganglion cells, and Frequency Doubling Technology Perimetry tests functions that should be primarily handled by the magnocellular ganglion cells. These new perimetric procedures are promising as improvements over standard automated perimetry; however, there is still no agreed upon method for determination of glaucomatous visual field progression.

Glaucoma Detection With Frequency Doubling Perimetry and Short-wavelength Perimetry

PURPOSE

The aim of this analysis was to evaluate the diagnostic usefulness of frequency doubling technology (FDT) perimetry and short-wavelength perimetry (SWAP). Moreover, to study a combination of both methods using the machine-learning technique double-bagging, which was recently established in glaucoma research.

METHODS

Forty-three patients with "preperimetric" open-angle glaucoma (glaucomatous optic disc atrophy and no visual field defect in standard perimetry), 26 patients with "perimetric" open angle glaucoma (glaucomatous optic disc atrophy and visual field defect in standard perimetry), and 40 control subjects had FDT screening (protocol: C-20-5) and SWAP (Octopus 101, G2). Criteria for exclusion were color vision abnormalities, media opacities, and an age below 31 years or above 63 years. Data of 1 eye of each patient and control subject entered the statistical evaluation. A point wise evaluation of the diagnostic power of SWAP values was performed to derive spatial patterns of visual field loss. A double-bagging machine-learning algorithm was used to train classification rules on the basis of a combination of FDT scores and nerve fiber related visual field losses in SWAP. The diagnostic power of the classifiers was compared regarding their misclassification error rates and area under the receiver-operating characteristic curve.

RESULTS

The combination of FDT perimetry and SWAP yielded better diagnostic results compared with FDT or SWAP separately. The overall estimated misclassification error rate of the combined classifier was 24% compared with 28% for both SWAP and FDT perimetry. Regarding the estimated performance of classifier at high specificities (>80%) in control eyes as measured by the partial area under the receiver-operating characteristic curve, the combination of both instruments is also superior to the individual instruments.

CONCLUSIONS

A combination of SWAP and FDT perimetry, each targeting different neuronal pathways, may improve early glaucoma detection.

Retinal Blood Flow Autoregulation after Dynamic Exercise in Healthy Young Subjects

PURPOSE

To evaluate the retinal blood flow before and after the increase in systemic blood pressure to assess the autoregulation in healthy young subjects.

METHODS

Twenty eyes of 20 healthy volunteers were examined. The retinal blood flow was assessed by a Heidelberg retina flowmeter (HRF), while the systemic pressure was assessed by a portable electronic sphygmomanometer. Furthermore intraocular pressure (IOP) was always measured by a Goldmann tonometer immediately after HRF assessments. All measurements of physiological and flow parameters were performed with the subjects seated at rest and then immediately after stair climbing.

RESULTS

The IOP decreased significantly after dynamic exercise, while the heart rate and the systemic artery pressure increased significantly. At the baseline, the mean retinal blood flow was 276.8 +/- 80.7 arbitrary units (AU) in the superotemporal area, 243.4 +/- 63.68 AU in the superonasal area, 258.2 +/- 67.37 AU in the inferotemporal area and 243.9 +/- 72.24 AU in the inferonasal area. After dynamic exercise the mean retinal blood flow was 249.8 +/- 86.78 AU in the superotemporal area, 248.7 +/- 63.87 AU in the superonasal area, 245.4 +/- 83.85 AU in the inferotemporal area and 228.8 +/- 62.53 AU in the inferonasal area. No significant change in retinal blood flow was found.

CONCLUSION

Our data support the hypothesis that in normal subjects autoregulation is sufficient to compensate the increase in blood pressure and maintain a stable retinal blood flow after exercise.

Glaucoma screening: analysis of conventional and telemedicine-friendly devices

PURPOSE

Portable, telemedicine-friendly devices offer novel opportunity for screening and monitoring glaucoma in the remote and rural regions of the world. This study examines the effective combination of telemedicine-friendly screening devices for detection of glaucoma in relation with conventional, hospital-based devices.

METHODS

A total of 399 eyes were screened with telemedicine-friendly devices and conventional, hospital-based devices such as ophthalmoscope, tonometer and perimeter.

RESULTS

Combination of age and family history of glaucoma alone has a sensitivity of 35.6% (specificity 94.2%, area under the curve 0.81, correctly classified 81.1%) and an addition of telemedicine-friendly or conventional visual field tests optimized the sensitivity to 91.1% (specificity 93.6%, area under the curve 0.95, correctly classified 93%). Analysis indicates good agreement between vertical cup-to-disc ratio by ophthalmoscopy and digital image reading. An addition of intraocular pressure test does not change sensitivity (35.6%) and specificity (94.2%).

CONCLUSION

This study indicates that evaluations of cup-to-disc ratio and visual field, using telemedicine-friendly devices, are most useful tools in screening for glaucoma. When used together these devices may be an alternative for conventional glaucoma screenings.

Staging Functional Damage in Glaucoma: Review of Different Classification Methods

Classification of glaucomatous visual field defects for different severity levels is important. The reasons for this are numerous, and include: to distinguish between healthy and diseased individuals, to have homogeneous grouping criteria when perimetry is used to define the severity of glaucoma, to adjust therapy on the basis of disease severity, to describe visual field conditions in a short and simple format, to monitor the progression of the disease, and to provide a common language for both clinical and research purposes. Many severity classification methods have been proposed, although none have had widespread use in clinical practice. Other methods, like the cumulative defect curve (Bebie curve), can be used to distinguish the type of visual field loss as diffuse, localized, or mixed. This article provides a review of the main classification methods that have been proposed in the past 40 years.

Comparison between indices of Humphrey matrix and Humphrey perimetry in early glaucoma patients and normal subjects

We compared visual field indices calculated by Humphrey matrix perimetry (HMP) and Humphrey perimetry (HP) in 62 early glaucoma patients and 587 normal subjects. Reliability indices, except for the false positive rate, were smaller when using HMP. Mean deviation (MD) and pattern standard deviation (PSD) calculated by HMP correlated with those by HP, but MD by HMP showed larger defects in early glaucoma patients. Thus, HMP might be more sensitive for detecting glaucomatous visual field loss.

Frequency Doubling Technology Perimetry in Open-angle Glaucoma Eyes With Hemifield Visual Field Damage: Comparison of High-tension and Normal-tension Groups

PURPOSE

To evaluate the performance of frequency doubling technology (FDT) perimetry in open-angle glaucoma eyes with hemifield visual field damage and to compare it between open-angle glaucoma with high pressure [high-tension glaucoma (HTG)] and those with normal pressure [normal-tension glaucoma (NTG)] groups.

METHODS

FDT perimetry with the N-30 full threshold protocol and standard automated perimetry (SAP) using the Humphrey Field Analyzer with the 30-2 full threshold protocol were performed in 20 eyes of 20 HTG patients and 36 eyes of 36 NTG patients with visual field damage confirmed with SAP in only one hemifield.

RESULTS

There was no significant difference in demographics, the Heidelberg Retina Tomography indices, and the Humphrey Field Analyzer indices between HTG and NTG groups. Regarding the FDT perimetry results, mean deviation in the global field (P=0.009) and mean sensitivity in the SAP-spared (P=0.001) and SAP-impaired (P=0.011) hemifields were lower; the numbers of FDT abnormal test points (probability of abnormality <5%) in the SAP-spared hemifield were significantly greater (P=0.005) in HTG than in NTG groups. Eyes in which FDT results of the SAP-spared hemifield were judged as abnormal was more frequent in HTG groups (P=0.007).

CONCLUSIONS

The performance of FDT perimetry to detect early or preperimetric glaucomatous functional changes should be different between HTG and NTG eyes.

Frequency-doubling technology: searching for the optimum diagnostic criteria for glaucoma

PURPOSE

To determine the diagnostic criteria of perimetry using frequency-doubling technology (FDT) with the best possible sensitivity-specificity balance for glaucoma diagnosis.

METHODS

A total of 92 healthy control subjects and 110 patients with varying degrees of glaucomatous visual field loss on standard automated perimetry (SAP) were used to obtain the best diagnostic criterion for the disease, by using screening C-20-1 and threshold C-20 strategies from original FDT perimetry. Another prospective sample of 52 normal eyes and 64 glaucoma eyes was used to test how well this optimum criterion performs in other populations. Receiver operating characteristic (ROC) curves were plotted for the number of altered points at each level of probability for the C-20-1 and threshold C-20 modes. In addition, ROC curves were calculated for the global indices of the threshold C-20 strategy.

RESULTS

The best criterion for the C-20-1 strategy is the presence of one or more altered points with p < 1% (57.81% sensitivity and 100% specificity). The optimum criteria for glaucoma diagnosis for the threshold C-20 strategy are the presence of five or more altered points with p < 5% and/or two or more altered points with p < 2% and/or at least one altered point with p < 1% at any location (79.68% sensitivity and 94.2% specificity).

CONCLUSIONS

By using the C-20-1 strategy, a p < 1% defect anywhere showed 100% specificity with the lowest test duration. The criteria proposed for the threshold C-20 algorithm presented a good sensitivity-specificity balance. The threshold C-20 test provides higher sensitivity than the C-20-1 strategy but takes about five times longer to perform.

A comparison of diagnostic protocols for interpretation of frequency doubling perimetry visual fields in glaucoma

BACKGROUND

Frequency doubling perimetry (FDP) shows good correlation with achromatic automated perimetry in the assessment of glaucoma. However, many recommended protocols lead to a significant number of false positives and negatives. Therefore, it may be difficult to identify visual field loss owing to glaucoma. We investigated the accuracy of a diagnostic protocol that only considered either temporal wedge, arcuate, or nasal step field loss on an FDP field as significant.

METHODS

Sixty-eight subjects who were glaucoma suspects, glaucoma patients or normal controls were recruited selectively. After achromatic automated perimetry and FDP visual field testing, results were compared between a conventional protocol and ones that took into account the position of FDP visual field loss.

RESULTS

If an FDP field was considered abnormal only when either a temporal wedge, an arcuate or a nasal step defect was present, the presence of a nasal step yielded the most accurate results with the least false positives (kappa coefficient=0.76) and with only minimal increase in false negatives, compared with a conventional FDP protocol (kappa coefficient=0.70).

CONCLUSIONS

Although, not statistically significant in this case, our results suggested a trend that a diagnostic protocol which considers nasal step FDP field loss significant may have a greater degree of accuracy when compared with conventional protocols and may facilitate interpretation in a clinical setting.

Frequency Doubling Technology Staging System 2

PURPOSE

To develop and evaluate a new staging system that can specifically be used for the classification of visual field defects with Humphrey Matrix Frequency Doubling 30-2 threshold test.

MATERIALS AND METHODS

The new frequency doubling technology staging system version (FDT SS 2) was created on the basis of a total of 200 tests obtained from 34 normal subjects, 67 patients with ocular hypertension (OHT), and 99 with primary open-angle chronic glaucoma (POAG). This system was used to classify defect severity in another group of 54 patients having POAG tested with the Humphrey Matrix 30-2 threshold test. A modified 5-stage classification method of Aulhorn and Karmeyer was taken as the gold standard. The reliability of FDT SS2 in categorizing according to type of defect (generalized, mixed, and localized) was also compared with a clinical classification on the basis of the analysis of probability maps. A control sample of 48 normal subjects was also analyzed.

RESULTS

With regards to the glaucomatous patients, 38 of 54 (70.4%) resulted with the same severity classification. All FDT SS2 grades (100%) were within 1 level of the clinical grade. The ability of FDT SS2 to correctly define the type of defect was also quite good (Spearman test: 0.719, P<0.001). In the control group, the FDT SS2 classified 45 of 48 cases as stage 0, giving a specificity of 93.7%.

CONCLUSIONS

The new FDT SS2 is able to both stage the severity of functional damage studied with the Humphrey Matrix 30-2 threshold test, and to correctly distinguish between generalized, localized, and mixed defects.

Correlation Between Frequency Doubling Technology and Heidelberg Retina Tomograph

PURPOSE

To evaluate the association between Heidelberg Retina Tomograph (HRT) parameters and the Frequency Doubling Technology (FDT) indices in ocular hypertension or primary open angle glaucoma patients.

METHODS

One eye was randomly chosen from 85 patients with primary open angle glaucoma (abnormal visual field and/or abnormal optic nerve and untreated IOP > 21 mm Hg) and ocular hypertension (normal visual field and normal optic nerve and untreated IOP > 21 mm Hg). All the patients were examined with Humphrey Perimeter program 30-2 full threshold, FDT program C 20-5, and HRT. Findings were analyzed using Pearson's correlation coefficient and linear regression.

RESULTS

Within the entire sample of studied subjects we found a statistically significant correlation (Pearson's r) (P < 0.05) between FDT mean deviation and RA, CA, RV, CSM, RNFLt, and RNFLc of HRT, and between FDT pattern standard deviation and RA, CA, VOLC, CV, RV, CSM, RNFLt, and RNFLc of HRT. Linear regression analysis showed that cup shape measure was the most predictive parameter for FDT MD. No correlation was found between HRT parameters and FDT PSD indices in the glaucoma subgroup; in the ocular hypertensive subgroup some correlation was found between FDT PSD and some of the HRT parameters.

CONCLUSION

In the entire group, cup shape measure showed to be the most significant factor correlating functional and morphologic changes. The presence of significant correlations between some HRT parameters and visual field indices in the ocular hypertensive and glaucoma subgroup suggested that HRT parameters and FDT indices could detect glaucoma damage differently.

Performance of community-based glaucoma screening using Frequency Doubling Technology and Heidelberg Retinal Tomography

PURPOSE

To assess the performance of a community-based glaucoma screening algorithm in the general population.

METHODS

A total of 659 individuals aged 50-90 years were screened for glaucoma. Presenting visual acuity, family history of glaucoma, FDT perimetry, and HRT tests were assessed. Additional samples of participants served as control groups. Participants identified as glaucoma positive received a full ophthalmic examination. Based on this exam a consensus diagnosis was made which served as the gold standard.

RESULTS

The optimal screening strategy combining visual acuity and family history with FDT and HRT had sensitivities, specificities, positive predictive values and negative predictive values of 96.8%, 89.7%, 31.9%, and 99.8% respectively for detecting glaucoma.

CONCLUSIONS

By combining assessments of presenting visual acuity and family history of glaucoma with Frequency Doubling Technology perimetry and Heidelberg Retina Tomography, we devised a community glaucoma-screening algorithm that showed a high sensitivity and specificity for detecting glaucoma in the general population.

Screening for primary open-angle glaucoma in the developed world: are we there yet?

BACKGROUND

In 1995, the Quebec Agency for Health Services and Technology Assessment (AETMIS) stated that a formal screening program for primary open-angle glaucoma (POAG) could not be recommended for the province of Quebec, owing to "a high degree of uncertainty and because of the high cost such a program would entail." The purpose of this article was to evaluate the possibility of instituting a POAG screening program in light of recent advances in the diagnosis and treatment of glaucoma.

METHODS

We reviewed new developments that have occurred since the mid to late 1990s in the field of glaucoma. Changes that could positively influence the feasibility and organization of future glaucoma screening programs were identified.

RESULTS

New technologies, including confocal scanning laser ophthalmoscopy (HRT II), optical coherence tomography (Stratus OCT), and scanning laser polarimetry with variable corneal compensation (GDx-VCC), permit early detection of optic nerve and nerve fibre layer structural damage. Together with advanced psychophysical tests (frequency doubling perimetry and short wavelength automated perimetry) for earlier detection of functional damage, they provide an increased understanding of the diagnosis and monitoring of POAG. Elevated intraocular pressure (IOP) remains the most important risk factor for glaucoma. Clinical trials indicate that lowering IOP at different stages of the disease can arrest or decrease its rate of progression. Moreover, it is important to assess pachymetry because IOP measurements are influenced by central corneal thickness. Finally, new treatments, such as prostaglandin analogues or selective laser trabeculoplasty, are safer and may also achieve lower intraocular pressures.

INTERPRETATION

Health policy involves the investment of public resources, and cost-effectiveness analyses for POAG screening are heavily weighted by the degree of uncertainty that glaucoma screening can be effectively and reliably achieved. The many new developments and advancements outlined herein, combined with the possible increasing prevalence of POAG, necessitate the re-evaluation of screening for primary open-angle glaucoma.

Evaluation of the high specificity Screening Program (C-20-1) of the Frequency Doubling Technology (FDT) perimeter in clinical practice

AIMS

To compare the efficacy of the high specificity Frequency Doubling Technology (FDT) Perimeter Screening Program (C-20-1) to standard threshold automated perimetry in the diagnosis of open-angle glaucoma.

METHODS

A total of 100 consecutively presenting patients attending a glaucoma clinic who volunteered for the study (approximately 30% of whom were attending for an initial visit) were examined with the FDT C-20-1 Screening Program and with the Humphrey Field Analyzer (HFA) SITA Fast algorithm and Program 24-2.

RESULTS

Of the patients, 17 were excluded due to unreliable visual field results or non-glaucomatous ocular abnormalities. In all, 10 patients were diagnosed as normal, 54 with open-angle glaucoma, eight with ocular hypertension, and 11 as glaucoma suspects. Of the 54 glaucomatous patients, 45 exhibited high-tension glaucoma and nine normal tension glaucoma. Perimetry with the HFA gave a sensitivity of 81.5% for the combined category of glaucoma and glaucoma suspect and a specificity of 83.3% for the combined category of normal and ocular hypertension. Perimetry with the FDT gave a sensitivity of 74.5% and a specificity of 85.2% compared to that of the HFA.

CONCLUSION

In the detection of glaucoma, Program C-20-1 of the FDT perimeter exhibits high specificity. It exhibits low sensitivity for the detection of mild loss but high sensitivity for advanced field loss relative to Program 24-2 and the SITA Fast algorithm of the HFA.

Effect of cataract surgery with intraocular lens implant on frequency doubling perimetry

PURPOSE

To study the effect of cataract surgery with intraocular lens (IOL) on frequency doubling perimetry (FDP).

METHODS

Patients aged 40 years or above seen at our outpatient clinic with no ocular pathology except for visually significant cataract and visual acuity 6/24 or better were eligible. They underwent FDP before and 4 to 6 weeks after cataract surgery with IOL.

RESULTS

Screening test: Mean scores by three different scoring methods were 1.82 (3.21), 2.80 (5.54), 4.18 (9.18) before and 0.22 (0.51), 0.26 (0.63), 0.26 (0.69) after surgery (p = 0.002 0.001, < 0.0001). Threshold test: Mean deviation (MD) and pattern standard deviation (PSD) were -5.23 (3.08) and 5.15 (2.78) before and -2.94 [corrected] (2.49) (p < 0.0001) and 5.21 (1.780) (p = 0.63) after surgery.

CONCLUSIONS

The screening test should be interpreted cautiously in the presence of cataract. On threshold testing, cataract surgery causes significant decrease in MD but no change in PSD.

Frequency doubling technology perimetry in non-arteritic ischaemic optic neuropathy with altitudinal defects

AIM

To determine if frequency doubling technology perimetry (FDT) is more sensitive to optic nerve injury in non-arteritic ischaemic optic neuropathy (NAION) than standard automated perimetry (SAP).

METHODS

Charts from 18 patients (20 eyes) with NAION with altitudinal defects who underwent a complete neuro-ophthalmic examination, SAP, and FDT were reviewed. The extent of damage as determined by SAP, FDT, and clinical estimation of the regional extent of optic disc pallor was compared. 10 subjects (20 eyes) with normal ocular examinations and full appearing optic nerve heads were included as a control group.

RESULTS

FDT demonstrated more extensive visual field defects in the relatively intact hemifield on SAP (proportion of locations at 5% or worse in the total deviation plot was 8.7% (SD 6.2%) for SAP and 38.3% (39.5%) for FDT p<0.0027). 16 of 20 eyes with altitudinal NAION demonstrated diffuse optic disc pallor. 11 of these eyes with diffuse pallor demonstrated significant defects in both hemifields using FDT, while only two eyes demonstrated diffuse damage using SAP. Correspondence between the extent of optic disc pallor and the extent of visual scotoma was higher for FDT (85%) than with SAP (40%).

CONCLUSION

FDT appears more sensitive to axonal injury reflected by the extent of optic disc pallor in altitudinal NAION than SAP and in some patients reveals visual dysfunction in the hemifield that appeared relatively uninvolved when evaluated using SAP.

Frequency Doubling Technology Threshold Testing in the Pediatric Age Group

PURPOSE

To evaluate the feasibility of performing visual field with the Frequency Doubling Technology (FDT) in children aged 5 to 10 years.

PATIENTS AND METHODS

Forty healthy children and fifteen healthy adults, all with no previous experience with visual field testing, underwent visual field testing with the C20 threshold test of the Carl Zeiss Meditec FDT analyzer in both eyes. The subjects were divided into three groups. Group A (age 5-7), group B (age 8-10), and group C (adults).

RESULTS

The mean explanation time for the test was 83 +/- 43 seconds for group A, 68 +/- 31 seconds for group B, and 37 +/- 15 seconds for group C (P < 0.001 for the difference between group C and groups A and B). Test performance time for the right eye was 347 +/- 57 seconds, 301 +/- 21 seconds, and 298 +/- 35 seconds for groups A to C, respectively (P < 0.001 for the difference between group A and groups B and C). Forty percent of the children, but none of the adults required two demonstrations prior to initiation of the test. In children fixation losses for the right and left eye were 10% and 37% respectively. No fixation losses occurred in adults. In both eyes a mean deviation <0.5% occurred significantly more often in group A than in group C (P = 0.013).

CONCLUSION

Visual field testing with FDT in the young age group is feasible. Test reliability was similar between children aged 5 to 7 and 8 to 10. Pre-selection of children is suggested to achieve reliable results.

Frequency doubling technology perimetry abnormalities as predictors of glaucomatous visual field loss

PURPOSE

To determine whether frequency doubling technology (FDT) perimetry results predict glaucomatous visual field defects, as assessed by standard automated perimetry (SAP), in a glaucoma suspect population.

DESIGN

Longitudinal observational study.

METHODS

The study included 105 eyes of 105 glaucoma suspect patients, with a mean follow-up time of 41 +/- 17 months. Glaucoma suspects had either intraocular pressure (IOP) higher than or equal to 23 mm Hg or glaucomatous optic neuropathy by stereophotograph assessment. All patients had normal SAP visual fields at baseline. A baseline FDT test was performed within 3 months of the normal SAP examination. Several baseline FDT parameters and other variables (age, gender, IOP, central corneal thickness, SAP visual field indices, and stereophotograph assessment) were investigated by univariate and multivariate Cox proportional hazards models to obtain hazard ratios (HR) and identify factors that predicted which patients had SAP glaucomatous visual field loss during follow-up.

RESULTS

Seventeen patients (16%) developed repeatable SAP visual field abnormality during follow-up. An abnormal FDT examination at baseline predicted the development of SAP visual field conversion in both univariate (HR = 3.17; 95% confidence interval [CI] = 1.22-8.25; P =.018) and multivariate models (Adjusted HR = 3.68; 95% CI = 1.06-12.8; P =.04). The analysis of FDT examinations during follow-up revealed that in 59% of converters the FDT abnormalities preceded SAP visual field loss by as much as 4 years. Also, the initial development of glaucomatous visual field loss as measured by SAP occurred in regions that had previously demonstrated abnormalities on FDT testing.

CONCLUSION

Functional abnormalities detected by FDT perimetry were predictive of the future onset and location of SAP visual field loss among glaucoma suspect patients.

Relationship between Indices of Humphrey Perimetry and Frequency Doubling Technology Perimetry in Glaucoma

PURPOSE

To study whether the correlation between indices of Humphrey perimetry and Frequency Doubling Technology (FDT) perimetry differs in the early and later stages of glaucoma.

METHODS

This study included 200 eyes of 200 patients with primary open-angle glaucoma or normal-tension glaucoma. The eyes were classified into the early and later stages by the median value (-4.51 dB) (Classification 1; n = 100 and 100, respectively) or the average value of the maximum and minimum values (-11.90 dB) (Classification 2; n = 165 and 35, respectively) of mean deviation (MD) obtained from a set of measurements with the Humphrey Full-Threshold 30-2 program in all eyes. The correlation between MD (H-MD) or pattern standard deviation (PSD) (H-PSD), as obtained from another set of measurements with the Humphrey Full-Threshold 30-2 program, and MD (F-MD) or PSD (F-PSD), as calculated by the Full-Threshold N-30 program of FDT perimetry, were evaluated using linear regression analysis.

RESULTS

Overall, H-MD and H-PSD significantly correlated with F-MD (r = 0.713; P < 0.001) and F-PSD (r = 0.731; P < 0.001), respectively. In each of Classifications 1 and 2, H-MD and H-PSD significantly correlated with F-MD and F-PSD, respectively, both in the early and later stages. However, in each classification, the correlation between H-MD and F-MD differed significantly between the two stages (Classification 1; P < 0.001; Classification 2, P = 0.003), while the correlation between H-PSD and F-PSD did not differ significantly between the two stages.

CONCLUSION

The degree of correlation between H-MD and F-MD differed between the early and later stages of glaucoma.

Dépistage du glaucome en Martinique : résultats au sein d’une population de 813 salariés hospitaliers

INTRODUCTION

Several US and Jamaican studies have shown that glaucoma is more severe in black populations than in Caucasian populations, which would lead to the assumption that the people of Martinique have a high glaucoma risk.

METHODS

A prospective study was conducted in workers of Fort de France University Hospital with the occupational medicine unit. Intraocular pressure was measured with a pulse air tonometer (Topcon CT 60) and visual field abnormalities were detected with automated perimetry using Humphrey frequency doubling technology (FDT). Patients with known glaucoma or with intraocular pressure over 21 mmHg and/or a visual field abnormality were referred to ophthalmology examination to diagnose ocular hypertension, open-angle glaucoma or normal-pressure glaucoma.

RESULTS

The occupational medicine unit examined 813 workers. The sex ratio was 0.36, mean age was 45.35+/-8.4 years (22-64 years), and mean ocular pressure was 12.1+/-2.62 mmHg (6-28 mmHg). Roughly 20% of workers had a family history of glaucoma. We found 22 patients with glaucoma (2.7%) (CI95: 1.6%-4%): 12 patients had open-angle glaucoma (1.5%) and 10 patients were diagnosed with normal-pressure glaucoma (1.3%). Glaucoma prevalence increased with age, reaching 8% in patients over 55 years of age. Of patients with normal-pressure glaucoma, 42.9% had a family history of glaucoma.

CONCLUSION

Our results confirm previous data from the literature that found higher glaucoma prevalence in black people and in particular in the mixed-race population of Martinique. In addition to this ethnic feature, the insularity of Martinique could support glaucoma expression. Easy and fast to use, FDT associated with the pulse air tonometer provides early detection of glaucoma.

Correlation Between Frequency Doubling Technology Perimetry and Scanning Laser Polarimetry in Glaucoma Suspects and Glaucomatous Eyes

The aim of this study was to determine the relationship between the frequency doubling technology (FDT) screening algorithm and parapapillary retinal nerve fiber layer (RNFL) thickness in the eyes of glaucoma suspects and patients with open angle glaucoma. FDT C20-1 screening program and a scanning laser polarimetry (SLP) system (GDx-NFA) was used to assess 53 glaucomatous eyes, 53 glaucoma suspects and 36 normal control eyes. In glaucomatous eyes, there were correlations between the FDT the screening algorithm and RNFL retardation values in several polarimetric indices, most significantly "inferior thickness" (r = -0.321, P = 0.029). In the eyes of glaucoma suspects, however, we observed no correlation between the FDT results and RNFL retardation values (r = 0.080, P > 0.05, "inferior thickness"). In glaucomatous eyes, the abnormal scores obtained with FDT screening program correlated negatively with RNFL retardation values, as measured by SLP. Despite poor correlation between the FDT abnormal score and RNFL retardation value in glaucoma suspects, detection of abnormality using the FDT screening protocol may aid in the assessment of early glaucomatous structural damage.

Staging of functional damage in glaucoma using frequency doubling technology

PURPOSE

To evaluate three new approaches for staging severity of glaucomatous visual field defects using frequency doubling technology.

PATIENTS AND METHODS

One hundred and four patients with either ocular hypertension or chronic glaucoma were tested with both standard automated perimetry (SAP, 30-2 Humphrey threshold test) and frequency doubling technology (N-30 threshold test). Standard automated perimetry results were classified into four groups (normal tests, early defects, moderate defects, and severe defects) using the Glaucoma Staging System. Frequency doubling technology tests were also classified in four groups using three different approaches: frequency doubling technology probability map analysis, considering the number and location of disturbed points, frequency doubling technology MD and PSD indices, graphed on a two-axis diagram (FDT Staging System), and an abnormality score, based on both the statistical significance and the spatial location of depressed points. A control group of 20 eyes from 20 normal subjects was also tested and classified in the same way. The Cohen Kappa was used to compare the level of agreement between the three frequency doubling technology methods of classification and the glaucoma staging system.

RESULTS

Measure of agreement was 0.679 using probability map assessment, 0.793 using the frequency doubling technology staging system, and 0.663 using the abnormality score. The specificity rate was 95% for all three methods.

CONCLUSIONS

All the studied approaches were able to correctly stage the glaucomatous functional damage, but the frequency doubling technology staging system was the easiest and quickest method. Moreover, it is the only method that supplies information on the characteristics of the defect, without requiring any other time-consuming procedures.

Corneal thickness measurements and frequency doubling technology perimetry abnormalities in ocular hypertensive eyes

OBJECTIVE

It has been suggested that some patients currently diagnosed with ocular hypertension (OHT) may have thicker than average corneas that result in an overestimation of their true intraocular pressure. Consequently, patients with OHT with greater corneal thickness may be at a lower risk for functional glaucomatous damage, including visual field loss measured with frequency doubling technology (FDT) perimetry. The purpose of this study was to evaluate the frequency of FDT perimetry deficits in patients with OHT and to correlate these findings with central corneal thickness (CCT) measurements.

DESIGN

Observational case control study.

PARTICIPANTS AND CONTROLS

Sixty-five patients with OHT with normal optic discs and normal standard achromatic automated perimetry (SAP) visual fields and 52 normal control subjects.

METHODS

All participants underwent SAP, FDT perimetry, and CCT measurements using ultrasound pachymetry.

MAIN OUTCOME MEASURES

CCT measurements in patients with OHT with abnormal repeatable FDT test results were compared with CCT measurements in patients with OHT with normal FDT results. In addition, CCT measurements in patients with OHT were compared with CCT measurements in normal control subjects.

RESULTS

Fourteen of 65 patients with OHT (21.5%) demonstrated repeatable FDT abnormalities. The mean CCT of patients with OHT with abnormal FDT results was significantly lower than the mean CCT of patients with OHT with normal FDT results (542+/-35 microm versus 575+/-35 microm; P = 0.003). The mean CCT in the normal control group was 556+/-36 microm. The mean CCT in patients with OHT with normal FDT results was significantly higher than in normal subjects (P = 0.008). No statistically significant difference was found between mean CCT in normal subjects and in patients with OHT with abnormal FDT results (P = 0.18).

CONCLUSIONS

Patients currently diagnosed with OHT, but with visual field loss detected by FDT perimetry, had significantly lower CCT measurements than patients with OHT with normal FDT results. These findings suggest that patients with OHT with thinner corneas are more likely to develop early glaucomatous functional damage and that CCT measurements should be taken into account when assessing risk for the development of glaucoma among OHT subjects.

A comparison of perimetric results with the Medmont and Humphrey perimeters

BACKGROUND

The Humphrey field analyser (HFA), Humphrey-Zeiss frequency doubling perimeter, and the Medmont automated perimeter (MAP) are three commonly used automated perimeters with threshold achromatic methodologies. Visual field loss may be detected earlier with strategies that target cell lines with reduced redundancy or which suffer selective damage.

METHOD

To compare these three perimeters, 63 subjects who were glaucoma suspects, ocular hypertensives, glaucoma patients, or normal controls were recruited selectively. All subjects underwent testing using MAP central threshold, MAP flicker perimetry, HFA full threshold, HFA SITA perimetry, HFA short wavelength perimetry (SWAP), and frequency doubling perimetry (FDP). After visual field testing, equivalent tests were compared: MAP central threshold with HFA full threshold and HFA SITA perimetry; Medmont flicker perimetry with HFA SWAP and FDP.

RESULTS

On analysis of the MAP central threshold a kappa statistic and an area under the receiver operator curve (AUC) of 0.90 and 0.94, respectively, were found compared with HFA full threshold strategies, and 0.87 and 0.92 respectively, compared with HFA SITA. For MAP flicker a kappa statistic and an AUC of 0.65 and 0.81, respectively, were found compared with HFA SWAP and 0.87 and 0.96, respectively, compared with FDP. A quadrant analysis and comparison of mean defect between tests was also highly significant.

CONCLUSION

Medmont and Humphrey perimeters correlated well; both may be used for clinical and research purposes with similar confidence.

Frequency doubling technology and high-pass resolution perimetry in glaucoma and ocular hypertension

PURPOSE

To study the correlation between frequency doubling technology perimetry (FDT) and high-pass resolution perimetry (HRP) in eyes with primary open-angle glaucoma, suspect glaucoma, ocular hypertension, and in normal eyes.

PATIENTS AND METHODS

Ninety-four patients (162 eyes) were studied. Visual fields were assessed by HRP, FDT screening C-20-5 and FDT threshold C-20 programs. In eyes with a discrepancy between the test results, a comprehensive clinical examination was performed, including optic disc photography and Heidelberg retinal tomography (HRT).

RESULTS

There was a strong correlation between HRP global deviation and the FDT mean deviation (for FDT threshold C-20 test), and between HRP score and FDT score (for FDT screening C-20-5 ). The correlation coefficients were r = -0.83 and r = 0.77, respectively. In all, 75 eyes (46.3%) had normal HRP and FDT screening results, while 67 eyes (41.4%) showed abnormal results in both tests. In 12 eyes (7.4%) HRP was within normal limits while FDT screening was abnormal. Seven of these eyes were judged to have glaucoma; three of them had converted from ocular hypertension to glaucoma. In eight eyes (4.9%) HRP was abnormal while FDT screening was normal. Three of these were judged to have glaucoma. Thus, the sensitivity and specificity of the FDT screening test for the detection of glaucoma were 91.7% and 87.8%, respectively.

CONCLUSION

There was a strong correlation between FDT threshold C-20, FDT screening C-20-5 and HRP test results. Frequency doubling technology perimetry C-20-5 represents a good screening test for the detection of optic nerve damage in open-angle glaucoma.

Is reading disability likely to interfere with glaucoma screening of adults using frequency-doubling technology perimetry?

PURPOSE

The present study is a preliminary investigation of whether frequency doubling technology perimetry (FDT) performance deficits exist in adults with reading disability (RD) and could thereby interfere with screening assessments for glaucoma.

DESIGN

Cross-sectional.

METHOD

The study population was composed of 46 college students. Twenty-four of the participants were identified as having a RD, and 22 served as controls. All participants underwent assessments of reading, IQ, FDT, Humphrey Visual Fields (HVF), and an ophthalmologic examination.

RESULTS

No differences between the RD and control groups were found in age, education, IQ, far visual acuity, HVF, or FDT performance, regardless of how FDT was evaluated (P's >.05).

CONCLUSIONS

Preliminary results indicate that FDT performance deficits, which have previously been demonstrated in children with RD, are either small in magnitude or do not exist in adults. Thus, it is unlikely that RD will interfere with assessment for glaucoma using FDT perimetry.

Agreement between frequency doubling perimetry and static perimetry in eyes with high tension glaucoma and normal tension glaucoma

AIMS

To investigate the agreement in results between frequency doubling technology (FDT) and the conventional automated static perimeter in eyes with normal tension glaucoma (NTG) and high tension glaucoma (HTG).

METHODS

72 eyes of 36 patients, who had two or more experiences with the Humphrey field analyser (HFA) program C30-2, were examined with the screening C-20-1 program of FDT. The result of FDT at each of the 17 stimulus points was graded as one of four categories. 58 out of 76 test points of HFA were assigned to one of the 17 clusters corresponding to FDT test points. Each cluster was represented as the lowest (scotoma of HFA) or the highest (threshold of HFA) probability symbol of total deviation (TD) of the HFA test points included in the cluster. The agreement between scotoma/threshold of HFA and FDT results was evaluated for NTG and HTG.

RESULTS

In a total of 65 eyes, the Spearman coefficients between the FDT and HFA (threshold/scotoma of HFA) were 0.599 and 0.515 (p<0.0001), respectively. In the HFA mean deviation matched 20 HTG eyes and 20 NTG eyes, the number of points with abnormal FDT results were 102 and 62 in eyes with HTG and NTG, respectively. The eyes with HTG had more abnormal FDT results than NTG eyes (p=0.0014, Mann-Whitney U test). The kappa coefficient between FDT and threshold of HFA in eyes with HTG and NTG was 0.288 and 0.520, respectively, and the agreement between FDT and scotoma of HFA was 0.480 and 0.439, respectively.

CONCLUSIONS

The best agreement of the results of FDT and HFA was observed in eyes with NTG using threshold of HFA. The eyes with HTG showed lower agreement with more abnormal points in FDT results, which suggests enough sensitivity of FDT in eyes with NTG, and higher sensitivity of FDT in eyes with HTG.

Combined use of frequency doubling perimetry and polarimetric measurements of retinal nerve fiber layer in glaucoma detection

PURPOSE

The aim of this study was to evaluate the diagnostic usefulness of the combined use of frequency-doubling technology (FDT) perimetry and polarimetry of the retinal nerve fiber layer.

DESIGN

Cross-sectional study.

METHODS

Seventy ocular hypertensive patients (normal optic disk and standard perimetry, elevated intraocular pressure [>21 mm Hg]), 59 patients with "preperimetric" open-angle glaucoma (glaucomatous optic disk atrophy, elevated intraocular pressure [>21 mm Hg], no visual field defect in standard perimetry), 105 patients with "perimetric" open-angle glaucoma (glaucomatous optic disk atrophy and clearly marked visual field defect), and 73 control subjects had FDT screening (protocol: C-20-5) and polarimetric measurements (GDx). Criteria for exclusion: optic disks larger than 4 mm(2), media opacities, patients younger than 33 years or older than 66 years. None of the subjects had earlier FDT perimetry. One eye of each patient and control subject entered the statistical evaluation. Database and statistical software were used for case-wise recalculation of all missed localized probability levels to create a FDT screening score.

RESULTS

At a predefined specificity of 94.5% in control eyes, discrimination between "perimetric" glaucoma and normal subjects is superior using the FDT perimetry (sensitivity = 84.8%) in comparison to polarimetry (sensitivity = 63.8%), whereas sensitivity is similar with both methods in "preperimetric" patients (GDx, FDT: 25.4%). In several cases, patients classified as glaucomatous by the GDx are not the same patients as identified by the FDT perimetry. Therefore, a two-dimensional discrimination analysis can increase correct positive classification. Using a linear combination of the present FDT screening score and polarimetry ("the number"), 92.4% of "perimetric" glaucoma eyes and 44.1% of "preperimetric" glaucoma eyes have been classified as glaucomatous.

CONCLUSION

Joint usage of polarimetry and FDT perimetry indicate that a combination of different techniques which can uncover different glaucoma properties, might be helpful in early glaucoma detection.

Detection of glaucomatous visual field defect by nonconventional perimetry

PURPOSE

To report the correlations among Humphrey Field Analyzer 750 (HFA), high-pass resolution perimetry (HRP), and frequency-doubling technology (FDT) perimetry in glaucoma patients and ocular hypertensive patients.

DESIGN

Cross-sectional study.

METHODS

Eighty-two eyes of 82 consecutive patients with primary open-angle glaucoma (POAG) or ocular hypertension were included in this study. One eye of each patient was randomly selected for data analysis. Visual fields were assessed by HFA, HRP, and FDT perimetry. HRP global deviation (HRP-GD), HRP local deviation (HRP-LD), FDT-mean deviation (FDT-MD), and FDT-pattern standard deviation (FDT-PSD) were considered for the analysis. Clinical agreement between HRP and FDT was evaluated. All data were analyzed by Pearson r coefficient when the distribution of the data was normal and by Spearman coefficient correlation when the distribution of the data was not normal. A P <.05 was considered statistically significant.

RESULTS

Fifty-two eyes (52 patients) were classified as glaucoma and 30 eyes (30 patients) as ocular hypertension. In the entire group, a significant (P >.001) correlation was found between the HFA indices and those of either HRP or FDT. A significant (P <.001) correlation was found between HRP-GD and FDT-MD as well as between HRP-LD and FDT-PSD. In 14% of the glaucomatous patients and in 33% of the subjects with ocular hypertension, FDT and HRP showed different clinical features.

CONCLUSIONS

Our data suggest that FDT and HRP are useful for detection of early glaucomatous visual field damage.