Standard achromatic perimetry, short wavelength automated perimetry, and frequency doubling technology for detection of glaucoma damage

Comparing retinal sensitivities on blue-on-yellow and green-on-yellow perimetry in glaucoma suspects

Purpose

To compare the retinal sensitivities between the blue-on-yellow perimetry (BYP)/short-wavelength automated perimetry (SWAP) and green-on-yellow perimetry (GYP) among patients with and without nuclear sclerosis among glaucoma suspects.

Methods

After ophthalmic examination, patients were subjected to two perimetric tests: BYP and GYP. The visual field (VF) parameters were compared between the two perimeters (p < 0.05 was considered significant).

Results

Fifty-five eyes of 39 patients with a mean age of 60.53 ± 9.70 years were included in the study. Twenty-one eyes had clear lens or pseudophakia. Twenty-six eyes had lower grades of nuclear sclerosis (NO2NC2, NO3NC3) and eight eyes had higher grades of cataract (NO4NC4, NO5NC5). The mean retinal sensitivity (RS) in BYP was 22.08 ± 5.02 (dB) and in GYP was 23.84 ± 5.50 (dB) (p = 0.08). The mean defect in BYP was -2.56 ± 4.40 (dB) and in GYP was -3.24 ± 5.05 (dB), pattern standard deviation (PSD) in BYP was 3.65 ± 1.91 (dB) and in GYP was 3.83 ± 1.99 (dB), and foveal threshold (FT) was 24.20 ± 4.32 (dB) in BYP and 28.10 ± 4.50 (dB) in GYP. The two perimeters showed good agreement by the Bland-Altman plot for all parameters. Fourteen eyes showed perimetric changes suggestive of glaucoma by BYP. In these, GYP had a sensitivity of 92.86% (95% CI of 66.13% to 99.82%) and specificity of 95.12% (95% CI of 83.47% to 99.40%).

Conclusion

BYP and GYP show good agreement. They are comparable in clear media as well as in different grades of nuclear sclerosis. GYP showed good sensitivity and specificity compared to BYP.

FDT Perimetry for Glaucoma Detection in Comprehensive Health Checkup Service

We aimed to investigate the efficacy of frequency doubling technology (FDT) perimetry for glaucoma detection in comprehensive screening examinations. We performed a retrospective analysis of prospectively collected data of participants who underwent a comprehensive health checkup service. Participants with glaucoma were excluded. In the first year, 2024 participants (46.8 ± 9.4 years) who underwent FDT perimetry and fundus photography were classified as the FDT group, whereas 3052 participants (42.2 ± 8.2 years) who underwent only fundus photography were classified as the non-FDT control group. Participants with abnormal findings on FDT perimetry and/or fundus photography were recommended to undergo further complete examination. All participants reported whether they had been newly diagnosed with glaucoma within 2 years of the first visit. In the FDT group, 23 (1.14%) participants were newly diagnosed with glaucoma. Among them, 20 (87.0%) had abnormal FDT perimetry findings and 12 (52.2%) had abnormal findings on fundus photography. The positive-predictive value (PPV) of FDT perimetry was 16.5% (20/121) and that of fundus photography was 13.3% (12/90). In participants with abnormal findings on both tests, the PPV was 26.2%. In the non-FDT group, 15 (0.49%) participants were newly diagnosed with glaucoma. Among them, 9 (60.0%) had abnormal findings on fundus photography. The PPV of fundus photography was 10.8% (9/83). The glaucoma detection rate, analyzed using age adjustment, was significantly higher in the FDT group than that in the non-FDT group (0.97% versus 0.47%, P=0.041). FDT perimetry, even if performed by nonspecialized physicians, could improve glaucoma detection when used in addition to fundus photography. This study was registered with UMIN000037951.

Validation and reproducibility of the Heidelberg Edge Perimeter in the detection of glaucomatous visual field defects

AIM

To validate the ability of the Heidelberg Edge Perimeter (HEP) in detecting glaucomatous visual field (VF) defects compared to the Octopus Visual Field (OVF) Analyzer and to determine the test-retest repeatability of both modalities.

METHODS

This prospective, cross-sectional study was conducted at Wills Eye Hospital, Philadelphia, PA. Glaucoma subjects and unaffected controls underwent VF testing using HEP standard automated perimetry (SAP) III 30-2 Adaptive Staircase Thresholding Algorithm (ASTA) FAST protocol and OVF G-TOP white-on-white strategy. Testing order was randomized. Pearson's correlation coefficient was calculated for both mean deviation (MD) and pattern standard deviation/square root of loss of variance (PSD/sLV). Receiver operating characteristic (ROC) curves were used to determine the diagnostic abilities of both modalities. Glaucoma subjects returned for repeat testing and intraclass correlation coefficients (ICCs) were calculated to assess test-retest repeatability.

RESULTS

Seventy-nine subjects with glaucoma and 36 unaffected controls were enrolled. HEP and OVF were significantly correlated for both MD (r=-0.84; P<0.01) and PSD/sLV (r=0.79; P<0.01). Areas under the ROC curves (AUCs) were also comparable between HEP and OVF for both MD (0.74 and 0.79, respectively; P=0.26) and PSD/sLV (0.74 and 0.82; P=0.08). ICC was high for both HEP (0.96 for MD, 0.95 for PSD/sLV) and OVF (0.82 and 0.88, respectively). Mean test duration (min) was significantly shorter for OVF (2.63) compared to HEP (5.15; P<0.01).

CONCLUSION

HEP and OVF show strong correlation for both MD and PSD/sLV, and have similar validity for detecting glaucoma. The test-retest repeatability is high for both HEP and OVF, however the average testing duration of HEP is significantly longer than that of OVF.

Short-Wavelength Automated Perimetry Parameters at Baseline and Following Remission in Patients With Birdshot Retinochoroidopathy

PURPOSE

To identify changes in short-wavelength automated perimetry patterns and parameters between the active and inactive states.

DESIGN

Retrospective cohort study with age-matched, normal controls.

METHODS

setting: Private tertiary referral center.

STUDY POPULATION

Seventy-five eyes of 38 patients with active birdshot retinochoroidopathy and 37 eyes of 37 historical normal controls.

INTERVENTION

Thirty-seven patients received immunomodulatory therapy. A fluocinolone acetonide intravitreal implant (Retisert) was implanted in both eyes of 1 patient as an initial treatment.

MAIN OUTCOME MEASURES

Changes in short-wavelength automated perimetry total deviation scores, pattern deviation scores, mean deviation, and pattern standard deviation in the active phase and the remission state.

RESULTS

Mean deviation (P = .006), pattern standard deviation (P = .001), total deviation score (P = .002), and pattern deviation score (P = .007) were significantly different from the active phase to the remission state. The length of time required to achieve remission did not significantly affect the changes in mean deviation (regression coefficient = 0.01; P = .92), pattern standard deviation (regression coefficient = 0.01; P = .87), total deviation score (regression coefficient = -0.1; P = .32), or pattern deviation score (regression coefficient = 0.1; P = .36) from the active phase to the remission state.

CONCLUSION

There was significant improvement in total deviation score, pattern deviation score, mean deviation, and pattern standard deviation on short-wavelength automated perimetry as patients achieved remission. Short-wavelength automated perimetry appears to be a useful and complementary modality in monitoring disease activity in birdshot retinochoroidopathy.

Clinical Clues to Predict the Presence of Parafoveal Scotoma on Humphrey 10-2 Visual Field Using a Humphrey 24-2 Visual Field

PURPOSE

To investigate characteristics related to the presence of parafoveal scotoma on Humphrey 10-2 visual field (VF) in early glaucoma patients.

DESIGN

Prospective, cross-sectional study.

METHODS

participants: Ninety-one eyes from 91 patients with glaucomatous optic neuropathy were prospectively tested with a 10-2 VF test.

OBSERVATION PROCEDURES

Glaucoma patients were classified into eyes with or without parafoveal scotoma on 10-2 VF based on pattern deviation plot. The central 10 degree region of Humphrey 24-2 VF test comprised 12 points and any abnormal VF points depressed <5%, <2%, <1%, or <0.5% from the normal database on pattern deviation plot were analyzed. Various factors related to the presence of parafoveal scotoma on 10-2 VF were analyzed.

MAIN OUTCOME MEASURES

Abnormal 24-2 VF points, macular ganglion cell-inner plexiform layer thickness.

RESULTS

The presence of abnormal 24-2 VF points <0.5% was significantly different between eyes with and without parafoveal scotoma on 10-2 VF (P < .01). The minimum macular ganglion cell-inner plexiform layer thickness (P = .04), any central 12 points depressed <0.5% on 24-2 VF (P < .01), and any central 12 points depressed <5% on 24-2 VF that spatially corresponds to macular ganglion cell-inner plexiform layer thinning (P < 0.01) were related factors to the presence of parafoveal scotoma on 10-2 VF.

CONCLUSIONS

Glaucomatous eyes with any abnormal 24-2 VF points on the central 10 degree region that are depressed <0.5% or <5% that correlates to macular ganglion cell-inner plexiform layer thinning should receive attention and be further evaluated with a 10-2 VF test.

Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes

Background:

Some diseases that affect the visual system may show loss of chromatic-achromatic sensitivity before obvious physical signs appear in the usual examination of the eye's posterior segment. A perimetric study has been conducted with four typical patients with glaucoma and diabetes, at different stages of the disease.

Materials and Methods:

In addition to the standard white-on-white (standard automated perimetry [SAP]), a test battery has been used to study patient's contrast sensitivity, using stimuli with different chromatic, spatial, and temporal content (multichannel perimetry). The choice of stimuli tries to maximize the response of different visual mechanisms: Achromatic (parvocellular and magnocellular origin); chromatic red-green (parvocellular origin); and chromatic blue-yellow (koniocellular origin).

Results:

The results seem to indicate losses in the achromatic-parvocellular perimetry and both chromatic perimetry tests, undetected by conventional SAP.

Conclusions:

Our results illustrate that our patients without visible retinal alterations show signs of suspicion in multichannel perimetry.

Comparison of SWAP and SAP on the point of glaucoma conversion

BACKGROUND

The purpose of this study was to compare the two perimetric modalities, SWAP (short wavelength automated perimetry) and SAP (standard automated perimetry), on the point of conversion to glaucoma.

METHODS

In this prospective, longitudinal, follow-up study, 282 patients with ocular hypertension were recruited consecutively and tested with both SAP and SWAP annually for 5 years or until the onset of conversion to glaucoma. SAP and SWAP perimetry was performed with the Humphrey Field Analyzer II using the 24-2 full-threshold test. Abnormality for both SAP and SWAP fields was determined on the pattern deviation plot and defined as either a) one point below the 0.5% probability level or b) a cluster of 2 or more points below 1% or c) a cluster of 3 or more points below 2% or d) a cluster of 4 or more points below 5%. Abnormal tests had to be confirmed on a subsequent test within one year to be classified as conversion.

RESULTS

Of the 282 patients initially recruited, 32 were excluded. Of the 250 remaining patients, a total of 38 converted during the follow-up period; 36.8% of conversions were detected earlier with SWAP, 29% simultaneously, and 34.2% were not detected with SWAP during the follow-up period; 2.4% of patients showed SWAP visual field loss that did not result in conversion during the follow-up period.

CONCLUSION

The results in our study are inconclusive. There were patients with earlier, simultaneous, or no SWAP conversion, with SAP conversion as the golden standard criterion. One should consider both SAP and SWAP with confirmation when visual field loss is evident to maximize early detection of glaucoma, because it appears that each method identifies early glaucoma in a subset of patients and these subsets overlap only partially.

Frequency doubling technique perimetry and spectral domain optical coherence tomography in patients with early glaucoma

PURPOSE

To assess the combined diagnostic power of frequency-doubling technique (FDT)-perimetry and retinal nerve fibre layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SDOCT).

METHODS

The study included 330 experienced participants in five age-related groups: 77 'preperimetric' open-angle glaucoma (OAG) patients, 52 'early' OAG, 50 'moderate' OAG, 54 ocular hypertensive patients, and 97 healthy subjects. For glaucoma assessment in all subjects conventional perimetry, evaluation of fundus photographs, FDT-perimetry and RNFL thickness measurement with SDOCT was done. Glaucomatous visual field defects were classified using the Glaucoma Staging System. FDT evaluation used a published method with casewise calculation of an 'FDT-score', including all missed localized probability levels. SDOCT evaluation used mean RNFL thickness and a new individual SDOCT-score considering normal confidence limits in 32 sectors of a peripapillary circular scan. To examine the joined value of both methods a combined score was introduced. Significance of the difference between Receiver-operating-characteristic (ROC) curves was calculated for a specificity of 96%.

RESULTS

Sensitivity in the preperimetric glaucoma group was 44% for SDOCT-score, 25% for FDT-score, and 44% for combined score, in the early glaucoma group 83, 81, and 89%, respectively, and in the moderate glaucoma group 94, 94, and 98%, respectively, all at a specificity of 96%. ROC performance of the newly developed combined score is significantly above single ROC curves of FDT-score in preperimetric and early OAG and above RNFL thickness in moderate OAG.

CONCLUSION

Combination of function and morphology by using the FDT-score and the SDOCT-score performs equal or even better than each single method alone.

The distribution of visual field defects per quadrant in standard automated perimetry as compared to frequency doubling technology perimetry

To test the ability of frequency doubling technology (FDT) perimetry to reveal defects in the same field quadrants as detected by standard automated perimetry (SAP). Ninety-two eyes with open-angle glaucoma and documented visual field defects by threshold SAP (Octopus Dynamic strategy) also underwent threshold FDT testing after successfully passing the FDT screening test. All eyes revealed varying stages of SAP defects while only 80 revealed FDT damage: 31:21 eyes in the early field loss stage, 36:35 in the moderate field loss stage, and 25:24 in the severe field loss stage in SAP versus FDT, respectively. SAP was able to detect abnormalities in 74 and 79% of the superotemporal, and inferotemporal quadrants, respectively, while the corresponding FDT figures were 70 and 69% for the same quadrants (P < 0.05 each). With regards to the nasal hemifield, SAP detected defects in 73 and 81% of the superonasal and inferonasal quadrants, respectively, compared to 69 and 66% for FDT (P < 0.001 each). The test duration per individual eye was significantly shorter with FDT than with SAP (P < 0.05). As well as the already established lower sensitivity of FDT compared to SAP, this study also demonstrated the significantly poorer ability of FDT in detecting the same field quadrant defects, especially in the early stages of glaucomatous damage.

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.

Rarebit perimetry and frequency doubling technology in patients with ocular hypertension

PURPOSE

To test the capability of rarebit perimetry (RP), a recent non-conventional perimetric technique, in detecting early functional damage in subjects with ocular hypertension (OHT) and to compare RP findings with those obtained by frequency-doubling technology (FDT) perimetry.

METHODS

Thirty patients with OHT were matched with 30 healthy subjects. All were tested with RP and FDT. Frequency-doubling technology mean deviation (MD) and pattern standard deviation (PSD), as well as RP mean hit rate (MHR), of the two groups were analyzed. The agreement between the two techniques was tested by Kappa analysis.

RESULTS

In the OHT group the mean (SD) FDT MD was 0.5 (2.1), the mean (SD) FDT PSD was 4.2 (1.6), and the mean (SD) RP MHR was 81.4 (6.7). In the control group, corresponding values were mean (SD) FDT MD 1.1 (1.4), mean (SD) FDT PSD 3.0 (0.3), mean (SD) RP MHR 96.2 (2.0). The differences between the two groups were not significant for the studied indexes. Eleven (36.6%) out of the 30 OHT eyes had abnormal RP results; 12 (40.0%) eyes had abnormal FDT results. Five (16.6%) eyes had abnormal RP and FDT findings. Only 1 eye (3.3%) in the control group had abnormal RP results and 3 eyes (10.0%) had abnormal FDT results. RP and FDT showed a moderate agreement (Kappa=0.43; 95% CI: 0.42 to 0.51).

CONCLUSIONS

RP and FDT showed VF defects not shown in standard automated perimetry in the OHT group. This may be indicative of an increased risk in developing glaucoma, even if a gold standard for detecting subtle defects is not currently available. RP has the additional advantage of not requiring any expensive device to be used. The poor agreement between these techniques in identifying eyes with early damage warrants further investigations. Large longitudinal studies are needed before defining the role of RP in early glaucoma diagnosis.

Influence of learning effect on blue-on-yellow perimetry

PURPOSE

Some studies have found that a significant blue-on-yellow perimetry (B/YP) learning effect exists in patients with ocular hypertension (OHT) or open-angle glaucoma who were experienced in standard automated perimetry. However, very little is known about the B/YP learning effect in normal subjects and patients without previous white-on-white perimetry (W/WP) experience. Meanwhile, it is unclear whether the B/YP learning effect is influenced by age and refraction.

METHODS

Twenty healthy subjects, 26 OHT and 14 primary open angle glaucoma (POAG) patients, underwent three full-threshold B/YP tests at intervals of 7 to 21 days. Of the 60 subjects, 38 had no previous W/WP experiences, 22 had previous W/WP experiences for at least two times. The parameters investigated to detect a learning effect were the perimetric indices and the test duration (TD).

RESULTS

Learning effects were demonstrated for mean deviation (MD), pattern standard deviation (PSD), short-term fluctuation (SF), and TD. Significant differences were found between the MD, PSD, SF, and TD of the first test and those of the second and third tests (p<0.05). However, no difference was found between those parameters of the second and third tests. No statistically significant differences were noted in terms of MD1st-2nd, MD1st-3rd, PSD1st-2nd, PSD1st-3rd, TD1st-2nd, and TD1st-3rd between the group with W/WP experience and the group without previous W/WP experience (p>0.05). No statistically significant differences were noted in terms of those parameters among the normal subjects and the patients with OHT or POAG (p>0.05). No significant difference was found in the B/YP learning effect among various age groups (p>0.05) and among various refraction groups (p>0.05).

CONCLUSIONS

A significant learning effect was observed between the first and the second or third tests and the perimetric indices appeared improved at full-threshold B/YP. The previous W/WP experience and the subject age and refraction did not influence the B/YP learning effect. This above all should be taken into account when considering the clinical use of this test to avoid erroneous diagnostic conclusions.

A visual field index for calculation of glaucoma rate of progression

PURPOSE

To present a new perimetric index for calculating the rate of glaucomatous progression and to compare its performance with the traditional mean deviation index (MDI).

DESIGN

Experimental study describing a device and retrospective cohort study.

METHODS

We developed a new visual field index, the glaucoma progression index (GPI), intended to be less affected by cataract than the MDI by calculating age-corrected defect depth at test points identified as significantly depressed in pattern deviation probability maps. The valid operating range for pattern deviation analysis was estimated. When exceeding this range, the total deviation probability maps were used for identification of significantly depressed points. The GPI is expressed in percentage, where 100% represents a normal visual field and 0% represents a perimetrically blind field, and is plotted vs patient age. Rate of progression, presented as yearly change in the GPI, is calculated by linear regression analysis. We conducted a pilot evaluation in three groups of patients: 1) eyes with developing cataract, 2) eyes without cataract, and 3) eyes in which cataract surgery was performed in the middle of the series.

RESULTS

The cut-off for pattern deviation was, at mean deviation, worse than -20 decibels (dB) in fields in which the eighty-fifth percentile of the total deviation value was significantly depressed. In the first group (n = 45), the measured rate of progression was greater with the MDI than with the GPI (P < .0001). The mean loss per year was 3.6%/year for the MDI and 2.1%/year for the GPI. In the second group (n = 42), the rate of progression did not differ between the MDI and the GPI (P = .52); the means were 2.7%/year and 2.6%/year, respectively. In the third group (n = 44), the confidence limits for the rate of progression were significantly smaller with the GPI than with the MDI (P = .04).

CONCLUSIONS

Glaucoma progression rates calculated using the GPI seem to be considerably less affected by cataract and cataract surgery than rates based on the traditional MDI.

Short-wavelength automated perimetry and frequency-doubling technology perimetry in glaucoma

Standard automated perimetry (SAP) is today still the clinical standard for the management of glaucoma and its progression, though it has been shown that it may detect the disease only after the death of a high number of retinal ganglion cells (RGCs). A number of "unconventional" perimetries have recently been evaluated by several clinical studies which showed their ability to identify the earliest glaucoma changes; the most promising of these techniques are short-wavelength automated perimetry (SWAP) and frequency-doubling technology perimetry (FDT). The applicability of these techniques is still limited by a number of factors: the limited economic resources allocated to perimetry; the paucity of well-conducted, prospective longitudinal studies showing the superiority of SWAP and FDT over SAP; and the lack of a consensus on the criteria to define test abnormality with these techniques. The aim of this article is to review the rationale, the limits, and the potentiality of SWAP and FDT for glaucoma management and to summarize the tasks required to improve the clinical usefulness of these two instruments in the future.

Diagnostic value of GDx polarimetry in a Taiwan Chinese population

PURPOSE

To study the diagnostic ability of scanning laser polarimetry with variable corneal compensation (GDx VCC) for early glaucomatous (EG) eyes and glaucoma-suspect (GS) eyes in a Taiwan Chinese population.

METHODS

This prospective cross-sectional study included 82 EG eyes (mean deviation, MD: -3.32 +/- 2.20 dB), 45 GS eyes (MD: -2.43 +/- 2.16 dB), and 62 normal eyes. Retinal nerve fiber layer thickness of each subject was measured using GDx VCC and Humphrey Field Analyzer visual field testing. Measured GDx VCC parameters were compared among groups. The area under the receiver operating characteristic (AROC) curve of each parameter was used to differentiate normal from EG eyes or GS eyes. The correlation between MD and each parameter was also evaluated.

RESULTS

For both normal versus EG and normal versus GS, the largest AROC values were for nerve fiber indicator, superior average thickness, and inferior average thickness. There was no significant correlation between MD and GDx-VCC-measured parameters either in EG or GS eyes.

CONCLUSIONS

GDx VCC shows only moderate ability to distinguish normal eyes from eyes with early glaucoma. However, its diagnostic role in eyes with suspicious discs and normal visual fields is uncertain at this moment in the Taiwan Chinese population. Further studies are needed to address this issue.

Can Frequency-doubling Technology and Short-wavelength Automated Perimetries Detect Visual Field Defects Before Standard Automated Perimetry in Patients With Preperimetric Glaucoma?

PURPOSE

To assess the ability of frequency-doubling technology (FDT) perimetry and short-wavelength automated perimetry (SWAP) to detect glaucomatous damage in preperimetric glaucoma subjects.

PARTICIPANTS

Two hundred seventy-eight eyes of 278 subjects categorized as normal eyes [n=98; intraocular pressure <20 mm Hg, normal optic disc appearance, and standard automated perimetry (SAP)]; preperimetric glaucoma eyes (n=109; normal SAP and retinal nerve fiber layer defects or localized optic disc notching and thinning); and glaucoma patients (n=71; intraocular pressure >21 mm Hg, optic disc compatible with glaucoma, and abnormal SAP).

METHODS

The preperimetric glaucoma group underwent at least 2 reliable full-threshold 24-2 Humphrey SAPs, full-threshold C-20 FDT, full-threshold 24-2 SWAP, optic disc topography using the Heidelberg Retina Tomograph II, laser polarimetry using the GDx VCC, and Optical Coherence Tomography (Zeiss Stratus OCT 3000). Receiver operating characteristic curves were plotted for the main Heidelberg Retina Tomograph, Optical Coherence Tomography, and GDx VCC parameters for the normal and glaucoma patients. The area under the receiver operating characteristic curve was used to determine the parameters indicating glaucomatous damage in the optic disc or retinal nerve fiber layer, which were used to establish additional subgroups of patients with preperimetric glaucoma. FDT and SWAP sensitivities were calculated for the patient subsets with structural damage and normal SAP.

RESULTS

At least 20% of the patients with preperimetric glaucoma demonstrated functional losses in FDT and SWAP. The more severe the structural damage, the greater the sensitivity for detecting glaucomatous visual field losses.

CONCLUSIONS

FDT and SWAP detect functional losses in cases of suspected glaucoma before glaucomatous losses detected by SAP.

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.

Frequency Doubling Perimetry and Short-Wavelength Automated Perimetry to Detect Early Glaucoma

PURPOSE

To compare the ability of short-wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) to detect early glaucoma damage.

DESIGN

Prospective case-control study using a comparative case series.

PARTICIPANTS

Forty-two patients with preperimetric glaucomatous optic nerve damage and a normal standard achromatic perimetry (SAP) in 1 eye, but with contralateral SAP abnormalities, and 35 normals.

METHODS

Forty-two patients and 35 normals underwent SWAP and FDP (Humphrey 24-2; Carl Zeiss Meditec, Inc., Dublin, CA). Correlations of mean deviation (MD) and pattern standard deviation (PSD) of the 2 groups were calculated. The number of defects at P<0.05 and P<0.01 on total deviation (TD) and pattern deviation (PD) plots were compared. Diagnostic precision and agreement on location of abnormalities were determined.

MAIN OUTCOME MEASURES

Correlations and comparisons of global indices between SWAP and FDP: MD, PSD, TD, and PD abnormal number of points.

RESULTS

Significant correlations in the glaucoma group were found between SWAP and FDP for MD (r = 0.54; P<0.008) and PSD (r = 0.49; P<0.001). Defects on the TD and PD plots were detected more frequently by FDP in the glaucoma group, although they were significant only for PD at P<0.01 (P = 0.024). Areas under receiver operator characteristic curves for MD of SWAP and PSD of FDP were 0.74 and 0.67, respectively (P = 0.37). Using defined defect criteria, FDP had a significantly higher sensitivity (72% vs. 54%; P = 0.02) and similar specificity (53% vs. 44%; P = 0.12) compared with SWAP. Agreement on defect location was moderate (kappa, 0.46). Testing time for SWAP was longer than for FDP in both glaucomatous and normal eyes (P<0.001).

CONCLUSIONS

Short-wavelength automated perimetry and FDP showed similar ability to detect visual dysfunction in patients with preperimetric glaucoma. Long-term follow-up is required to define their role in predicting subsequent SAP defects.

The Influence of Learning Effect on Frequency Doubling Technology Perimetry (Matrix)

PURPOSE

To determine learning effect in healthy patients without perimetric experience, tested with the frequency doubling technology perimetry, with the new model Matrix.

PATIENTS AND METHODS

Frequency doubling technology in the 30-2 threshold mode was performed on 37 healthy subjects. Each subject was tested twice in different sessions. The test always began with the right eye (RE) and continued with the left eye (LE). To evaluate learning effect the results of the REs at the first session were compared with those of the LE. The following parameters were evaluated: foveal threshold (FT), reliability indexes, mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), duration of examination.

RESULTS

At the first session the average values of RE were FT=30.81 db, MD=-1 db, PSD=3.01 db, and duration of the examination=383.27 "and of LE were FT=30.73, MD=-0.79 db, PSD=2.97 db, and duration of examination 382.62." At the second session the average values of RE were FT=32.22 db, MD=+0.16 db, PSD 2.75 db, and duration of examination=374.97 db. The reliability was different and the GHT between the RE and LE in the first and second session was also different.

CONCLUSIONS

A learning effect was observed between the first and the second sessions and the results of the GHT appeared improved. This above all should be taken into account when considering the clinical use of this test to avoid erroneous diagnostic conclusions.

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.

Selective perimetry in glaucoma diagnosis

PURPOSE OF REVIEW

Selective perimetry evaluates visual function by using visual stimuli that attempt to target specific subpopulations of retinal ganglion cells, which is designed to improve sensitivity to detect glaucomatous functional loss. This paper reviews recent studies that have assessed the characteristics of new strategies/programs of selective perimetry.

RECENT FINDINGS

Selective perimetry is usually compared against an existing standard technique--standard automated perimetry. Recent studies did not consider standard automated perimetry results as part of inclusion/exclusion criteria, avoiding selection bias and permitting fair comparisons between perimetry techniques. Furthermore, the Swedish Interactive Threshold Algorithm is replacing Full-Threshold as the standard automated perimetry gold-standard strategy, and comparisons of the diagnostic performance of function-specific perimetry may be influenced by which standard automated perimetry technique is used as the reference. These factors may impact our perception about the role of selective perimetry in glaucoma management.

SUMMARY

The lack of a perfect gold-standard diagnostic test for glaucoma limits the interpretation of results from cross-sectional studies evaluating visual field tests. Nevertheless, evidence suggests that visual dysfunction in eyes with early glaucoma varies significantly between individuals and no single technique is superior to the others in all patients. A multimodal functional assessment may be more effective in detecting/quantifying visual impairment associated with early glaucoma.

Frequency-doubling perimetry: comparison with standard automated perimetry to detect glaucoma

PURPOSE

To compare second generation frequency-doubling perimetry (FDP) with standard automated perimetry (SAP) to detect glaucomatous visual field abnormalities.

DESIGN

Prospective, cross-sectional, controlled observational study.

METHODS

Fifty eyes of 50 patients with glaucoma with confirmed SAP visual field abnormalities and 42 eyes from 42 normal control subjects were studied. Swedish Interactive Thresholding Algorithm (SITA) standard 24-2 SAP and FDP visual fields were performed. The correlation of global indices and the number of defects on total deviation (TD) and pattern deviation (PD) plots were compared. The spatial concordance of FDP and SAP defect locations was determined.

RESULTS

In patients with glaucoma, significant correlations of mean deviation (MD) and pattern standard deviation (PSD) were found between SAP and FDP (P < .001 for MD and P < .001 for PSD), but not in the normal group. FDP had significantly greater defect scores than SAP on total deviation and PD plots in the glaucoma group (P = .028 and P = .01, respectively). In comparison with SAP, sensitivity and specificity of FDP were 92% and 98% with glaucoma hemifield test criteria and 98% and 93% with PSD <5% criteria, respectively. Similarly high diagnostic precision was found with MD and PSD (at 95% specificity; MD and PSD sensitivity was 82% and 90%, respectively). The location of defects within 12 hemifield clusters found with FDP agreed moderately well with those detected with SAP (kappa = .48).

CONCLUSIONS

FDP and SAP perform similarly in their ability to detect visual field defects in early to moderate glaucoma. Larger and deeper defects detected with FDP suggests the possibility of earlier detection at high specificity.

Flimmerprovokation im LED-Ganzfeld bei Gesunden und Glaukompatienten

BACKGROUND

Flicker light is an easy method to test sensory function after stress. The aim of this study was to determine the influence of flicker stress on temporal contrast sensitivity in healthy controls and patients with glaucomatous alteration of the optic disk.

METHODS

A commercially available full-field stimulator (Retiport, Roland Consult) equipped with white LEDs was modified to perform psychophysical tests. The patients underwent measurements of the recovery time interval from cessation of flicker stress until recognition of a pregiven flicker contrast after photo stress. In addition, we studied contrast sensitivity with a continuous flickering target and with a flicker burst protocol avoiding adaptation to prevailing flicker. All tests were performed at a constant retinal illumination and at a frequency of 37 Hz for provocation as well as for contrast sensitivity tests.

SUBJECTS

Normal healthy controls (40), "preperimetric" (62), and "perimetric" (52) open-angle glaucoma patients were studied. Exclusion criteria were age lower than 31 years, visual acuity under 0.6, and perimetric mean defect more than 9.5 dB.

RESULTS

Recovery time after flicker stress was significantly longer in patients than in normals and longer in perimetric than in preperimetric patients. Analysis in perimetric patients revealed a larger area under ROC for the provocation test (0.95) than in contrast sensitivity tests (continuous flicker method: 0.90, flicker burst mode: 0.84).

CONCLUSION

High-power LEDs which are installed in modern full-field devices can be used as a helpful tool to study psychophysical properties. In the present study it could be shown that threshold, adaptation, and recovery of temporal transfer characteristics are impaired in many patients with glaucoma.

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.

Agreement and repeatability for standard automated perimetry and confocal scanning laser ophthalmoscopy in the diagnostic innovations in glaucoma study

PURPOSE

To assess agreement between structural and functional testing in classifying eyes as normal or abnormal and their repeatability on two consecutive visits by means of standard automated perimetry (SAP) and confocal scanning laser ophthalmoscopy.

DESIGN

Analysis of selected data obtained from a prospective longitudinal observational cohort study, the Diagnostic Innovations in Glaucoma Study.

METHODS

One hundred fifty-one participants with a SAP and a Heidelberg Retina Tomograph (HRT) test within a three-month window at two visits within 15 months were included. Eyes were classified by SAP and HRT at each visit. Agreement and repeatability were assessed by kappa statistics.

RESULTS

At visit 1, 33 (22%) of 151 eyes had only SAP defects, 11 (7%) eyes had only HRT defects, and 35 (23%) eyes had both SAP and HRT defects. Seventy-two eyes (48%) were classified as normal by both tests. Similar results were obtained for visit 2. The agreement between SAP and HRT in classifying eyes was 70% (kappa = 0.393) at visit one and 68% (kappa = 0.363) at visit 2. Repeatability of classification by SAP alone, HRT alone, and both SAP and HRT between visits 1 and 2 was 84% (kappa = 0.693), 89% (kappa = 0.752), and 90% (kappa = 0.723), respectively.

CONCLUSIONS

Agreement between SAP and HRT was only fair at both visits. Repeatability across visits was substantial for SAP alone, HRT alone, and for the combination of SAP and HRT. These results suggest that detection of particular features of glaucomatous damage depends on the technique used. Structural and functional tests appear complementary, and both should be used for early detection of glaucoma.

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.

Diagnostic sensitivity of fast blue-yellow and standard automated perimetry in early glaucoma: a comparison between different test programs

PURPOSE

To compare the ability of Fast Swedish interactive threshold algorithm (SITA) short-wavelength automated perimetry (SWAP), lengthier full-threshold SWAP, and standard automated perimetry (SAP) using the SITA Fast program to detect early glaucomatous visual field loss.

DESIGN

Cross-sectional prospective study of perimetric diagnostic sensitivity as defined by reference limits determined in the same healthy participants for all 3 test programs.

PARTICIPANTS

One hundred one patients with ocular hypertension, or suspect or early manifest glaucoma.

METHODS

One eye of each patient was tested with 2 blue-yellow perimetric programs: the SITA and full-threshold SWAP and the SAP SITA Fast program.

MAIN OUTCOME MEASURES

Glaucomatous visual field loss, defined as number of significantly depressed test point locations or the number of clusters of such test points.

RESULTS

No significant difference in number of significantly depressed test point locations between the 3 programs could be detected, neither at the P<5% limit nor at the P<2% limit. The difference in number of points depressed below the fifth percentile was 0.5 between full-threshold SWAP and SITA SWAP, 1.09 between full-threshold SWAP and SAP, and 1.04 between SITA SWAP and SAP. The number of eyes showing clusters of significantly depressed points also was similar with the 3 test programs: full-threshold SWAP identified clusters in 66 eyes, SITA SWAP identified clusters in 67 eyes, and SITA Fast SAP identified clusters in 65 eyes. Average test time was 12.0 minutes using full-threshold SWAP, 4.1 minutes with SITA SWAP, and 3.5 with SITA Fast.

CONCLUSIONS

The SITA SWAP identified at least as much glaucomatous visual field loss as the older full-threshold SWAP, although test time was considerably reduced. Conventional SAP using SITA Fast was not significantly less sensitive than either of the 2 SWAP programs.

Visual field testing with the new Humphrey Matrix: a comparison between the FDT N-30 and Matrix N-30-F tests

PURPOSE

To determine if the N-30-F test with the new Humphrey Matrix instrument is comparable to the traditional frequency-doubling technology (FDT) N-30 test.

METHODS

A sample of 47 eyes from 47 patients (five normal subjects, 27 with ocular hypertension and 15 with glaucoma) underwent visual field (VF) testing with standard automated perimetry, and with FDT, using the FDT N-30 program, and the Matrix N-30-F program (using the same 19 tested points, full-threshold strategy, but with an enhanced algorithm to reduce testing time). The plots, mean deviation (MD), pattern standard deviation (PSD), defect locations and test time were compared.

RESULTS

The agreement between the two tests was shown to be good, except for subjects with large VF defects, in which greater PSD values were observed with the FDT test, whereas the Matrix test gave a higher MD and number of abnormal test locations in the total deviation plot. A lack of agreement was also found for the number of abnormal test locations on the pattern deviation plot at any VF loss severity level. The test time for the Matrix test was significantly shorter.

CONCLUSION

The FDT N-30 and Matrix N-30-F tests proved to be comparable in cases of early to moderate VF defects.

Frequency doubling technology perimetry with the Humphrey Matrix 30-2 test

PURPOSE

To assess the Humphrey Matrix 30-2 test in detecting functional glaucomatous damage.

PATIENTS AND METHODS

One eye in each of 60 healthy individuals, 108 patients with ocular hypertension (OHT), and 150 patients with preperimetric (48) or perimetric (102) high-tension primary open-angle glaucoma (POAG) were considered. Visual fields were assessed by the standard automated perimetry (SAP) Humphrey Field Analyzer 30-2, frequency doubling technology (FDT) N-30, and Humphrey Matrix 30-2 tests. Significantly abnormal points in the pattern deviation probability plot, testing time, sensitivity, specificity, and area under the receiver operating characteristic curve of the FDT tests were evaluated.

RESULTS

FDT revealed a significantly greater percentage of depressed points than did SAP in OHT and preperimetric POAG eyes. The FDT-N-30 test showed a significantly greater percentage of areas with P < 5% in the OHT, preperimetric POAG, and early POAG groups. The Matrix-30-2 test provided an area under the receiver operating characteristic curve slightly lower than the FDT-N-30 test in the preperimetric POAG group, and significantly greater in the perimetric POAG group.

CONCLUSIONS

FDT perimetry appeared more sensitive than SAP in detecting early glaucomatous VF loss. The FDT-N-30 test showed a slightly higher ability to detect early glaucomatous damage in patients at risk for the development of glaucoma, whereas the Matrix-30-2 test provided a more detailed characterization of the glaucomatous VF loss pattern, although it required 30% more time.

Prediction of future scotoma on conventional automated static perimetry using frequency doubling technology perimetry

AIM

To see if scotoma detected with frequency doubling technology (FDT) is confirmed by Humphrey field analyser (HFA) 3 years later.

METHODS

Subjects were first examined with the screening C-20-1 program of FDT. The visual field was examined annually for 4 years using HFA program C30-2. The central 58 test points in HFA were assigned to one of the 17 clusters corresponding to FDT test points. Each cluster was represented as the lowest probability symbol of total deviation (TD) of the HFA test points included in the cluster. Clusters were graded normal, suspected scotoma, and scotoma depending on probability of TD-5% or more, 5%-1%, less than 1%, respectively. Relative risk (RR) of abnormality on FDT for future scotoma on HFA was estimated.

RESULTS

80 eyes of 42 patients were followed up for 4 years. While 4.0% of normal clusters of HFA with normal FDT results developed into scotoma cluster, 20.8% of normal clusters with abnormal FDT results developed into scotoma cluster with HFA at the third year. RR for future scotoma was 5.24 (95% CI, 2.75 to 10.0, p<0.05).

CONCLUSION

An abnormal result in FDT shows a high risk of future scotoma on HFA after 3 years even if the original HFA perimetry showed normal results.

Detecting glaucoma with frequency-doubling technology perimetry: a comparison between N-30 and C-20 screening programs

PURPOSE

To evaluate the ability of frequency-doubling technology (FDT) perimetry in detecting glaucoma with N-30 and C-20 screening programs.

METHODS

Eighty eyes of 80 patients were enrolled (40 glaucomatous, 40 controls). Humphrey achromatic perimetry (standard automated perimetry, SAP) was considered as the "gold standard" for diagnosis. To assess whether N-30 screening program could detect more initial glaucomatous defects than C-20, glaucomatous patients included 20 cases with nasal step at SAP (pre-selected by medical chart inspection). Patients underwent two SAP examinations to confirm diagnosis; then two N-30 and two C-20 screening tests with frequency-doubling technology were performed in a randomized sequence. Finally, a frequency-doubling technology N-30 full-threshold examination was performed. Several criteria to define abnormality at frequency-doubling technology screening programs were evaluated.

RESULTS

For both C-20 and N-30 screening programs, the best parameter to detect glaucoma was the presence of at least 1 point with P < 5% (sensitivity = 87.5% for both tests and specificity of 90% and 95% for C-20 and N-30, respectively). Both screening procedures obtained a lower sensitivity (75%) in patients with a nasal step, whereas frequency-doubling technology full-threshold program was able to detect the initial defects in all cases.

CONCLUSIONS

N-30 and C-20 screening procedures obtained similar results in well-defined glaucoma patients in terms of sensitivity and specificity. In the presence of a standard automated perimetry nasal step, diagnostic ability with both frequency-doubling technology screening strategies decreased and one quarter of nasal steps went undetected.

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.

Corneal thickness and functional damage in patients with ocular hypertension

PURPOSE

To correlate functional damage over time detected by standard automated perimetry (SAP) and frequency doubling technology (FDT) with central corneal thickness (CCT) in patients with ocular hypertension (OHT).

METHODS

Seventy-eight OHT patients underwent CCT measurements, SAP, and FDT (the latter two also after 12 and 18 months). Patients were divided into three equally sized groups of 26 patients each: thin (< 540 microm), normal (540-580 microm), and thick cornea (> 580 microm). The frequency of abnormal FDT and SAP results was analyzed over time (Pearson chi2 test).

RESULTS

Six of 26 patients with thin corneas (23.1%) presented an abnormal FDT test at baseline, compared to 1 of 26 (3.8%) in the normal thickness cornea group and 1 of 26 (3.8%) in the thick cornea group. After 12 months, the abnormal FDT tests were as follows, respectively: 9 of 26 (34.6%), 2 of 26 (7.7%), and 2 of 26 (7.7%). For SAP the abnormal results were as follows, respectively: 8 (30.1%), 5 (19.2%), and 2 (7.7%). After 18 months, the abnormal FDT tests were as follows, respectively: 16 (61.5%), 5 (19.2%), and 5 (19.2%). For SAP, the abnormal results were as follows, respectively: 10 (38.5%), 5 (19.2%), and 2 (7.7%).

CONCLUSIONS

OHT patients with thinner corneas have a greater risk of developing functional damage over time.

Short-wavelength automated perimetry results are correlated with optical coherence tomography retinal nerve fiber layer thickness measurements in glaucomatous eyes

PURPOSE

To determine the relationship between retinal nerve fiber layer (RNFL) thickness measured using optical coherence tomography (OCT) and short wavelength-sensitive visual function measured using short-wavelength automated perimetry (SWAP).

DESIGN

Retrospective observational case series.

METHODS

Subjects were recruited from the longitudinal University of California, San Diego, Diagnostic Innovations in Glaucoma Study and included 29 glaucoma patients with OCT imaging and reliable SWAP visual field (VF) testing within a 6-month window.

MAIN OUTCOME MEASURES

Correlations between deviation from normal (thinner than 97.5% of normal) RNFL measurements taken at 30 degrees sectors (12 sectors described as clock hours) and SWAP average pattern deviation within 21 VF zones were determined. The number of OCT-measured RNFL sectors outside of normal limits and the number of VF zones outside of normal limits also were compared.

RESULTS

The OCT nerve fiber layer thickness was outside of the normal limits in at least 1 sector in 26 (89.6%) patients. Twenty-eight (96.5%) patients had at least 1 SWAP VF zone outside of normal limits. Optical coherence tomography sectors 6-o'clock, 7-o'clock, and 8-o'clock (inferior and inferotemporal) and SWAP VF zones 13, 14, and 16 (superior hemifield central and arcuate areas) were the most frequently damaged. In general, the strongest R2 associations were between inferior and inferior temporal RNFL sectors (e.g., 6-o'clock, 7-o'clock) and superior nasal/arcuate VF zones (e.g., zones 13, 14, 15) and between superior and superior temporal RNFL sectors (e.g., 12-o'clock, 11-o'clock) and inferior central and arcuate VF zones (e.g., zones 5, 6, 7) (R2 range = 24.3%-37.3%, all Ps < or = 0.005). Most nonsignificant associations were found between superior RNFL sectors and superior VF zones.

CONCLUSION

Retinal nerve fiber layer thickness measured with OCT is topographically correlated with glaucomatous VF defects measured with SWAP.

Beyond visual acuity: new and complementary tests of visual function

Visual acuity is an essential component of the routine ophthalmic examination and the most common measure of visual function. There is increasing recognition, however, of the need to evaluate visual function beyond the limited extent afforded by visual acuity. The primary objective of this article is to introduce a variety of new and lesser-used techniques for measuring visual function that complement visual acuity assessment, each of which has been shown to detect visual dysfunction in patients with normal visual acuity.

Optical coherence tomography measurement of nerve fiber layer thickness and the likelihood of a visual field defect

PURPOSE

To determine if optical coherence tomography (OCT) measurements of nerve fiber layer (NFL) thickness can be used to predict the presence of visual field defects (VFD) associated with glaucoma.

DESIGN

Quota-sampled, cross-sectional study.

METHODS

Retrospective study of OCT NFL thickness measurements in 276 eyes of 276 subjects. All persons received OCT NFL thickness analysis; 136 eyes underwent frequency-doubling technology (FDT) perimetry; and 140 eyes underwent Swedish interactive threshold algorithm (SITA) perimetry. We defined a parameter called NFL(50), which is the NFL thickness value at which there was a 50% likelihood of a VFD with either SITA or FDT perimetry. We evaluated the use of NFL(50).

RESULTS

The mean NFL thickness with (n = 68) and without (n = 68) a VFD in the FDT group was 93.2 microm +/- 22.6 and 108.4 microm +/- 14.1, respectively. The mean NFL thickness with (n = 70) and without (n = 70) a VFD in the SITA group was 78.9 microm +/- 24.8 and 103.0 microm +/- 18.0, respectively. The FDT mean NFL(50) value was 98.5 microm. The SITA mean NFL(50) value was 87.0 microm. The area under the receiver operator characteristic (AROC) curve for mean NFL was 0.73, and the positive predictive value (PPV) for FDT mean NFL(50) was 72.2%. For SITA mean NFL, the AROC was 0.79 and the PPV for NFL(50) was 77.2%.

CONCLUSION

Nerve fiber layer thickness analysis using OCT may be clinically useful in identifying subjects who have visual field loss. However, the PPV suggests that OCT may need higher resolution and better reproducibility to enhance its sensitivity and specificity for population screening.