Optimum criteria for short-wavelength automated perimetry

Relationship between short-wavelength automatic perimetry and Heidelberg retina tomograph parameters in eyes with ocular hypertension

AIM

To compare and correlate optic nerve head parameters obtained by Heidelberg retina tomograph (HRT) with short-wavelength automatic perimetry (SWAP) indices in eyes with ocular hypertension (OHT).

METHODS

One hundred and forty-six patients with OHT included in the present study. All subjects had reliable SWAP and HRT measurements performed within a 2wk period. The eyes were classified as normal/abnormal according to visual field criteria and Moorfields regression analysis (MRA). Correlations between visual field indices and HRT parameters were analyzed using Pearson correlation coefficient (r).

RESULTS

Twenty-nine eyes (19.9%) had SWAP defects. Twenty-nine eyes (19.9%) were classified as abnormal according to global MRA. Six eyes (4.1%) had abnormal global MRA and SWAP defects. The k statistic is 0.116 (P=0.12) indicating a very poor agreement between the methods. No statistical significant correlation between HRT and SWAP parameters was detected.

CONCLUSION

SWAP defects may coexist with abnormalities of optic disc detected by HRT in eyes with OHT. In most eyes, however, the two methods detect different glaucoma properties.

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.

Performance of imaging devices versus optic disc and fiber layer photography in a clinical practice guideline for glaucoma diagnosis

PURPOSE

To compare the performance of Moorfields Regression Analysis (MRA) and optical coherence tomography (OCT) with that of photographic evaluation of the optic nerve head and retinal nerve fiber layer (RNFL) in the application of the Finnish Evidence-Based Guideline for Open-Angle Glaucoma (FEBG-OAG).

METHODS

Patients referred for glaucoma evaluation (n=312) and subjects selected from the general population (n=41) were included in the study. All subjects underwent ophthalmic evaluation, optic nerve head stereophotography, monochromatic RNFL photography, Heidelberg retina tomography, OCT, and laser polarimetry evaluation. The subjects were classified based on stereophotographic or MRA and OCT results by applying the FEBG-OAG.

RESULTS

The specificity of the FEBG-OAG for detecting normal patients (stereophotography and imaging devices) was 78% (strict criteria) and 100% (liberal criteria). Agreement between the stereophotographic evaluation and evaluation based on MRA and OCT was 70.2%. Classification of subjects with similar management advice based on these evaluations had 70.5% agreement. Central corneal thickness was a confounding factor in glaucoma diagnosis. Large optic disc sizes played a major role in misleading the diagnosis compared to small discs.

CONCLUSIONS

Central corneal thickness and large optic disc size are confounding factors in glaucoma diagnosis. Moorfields Regression Analysis and OCT allow for objective implementation of the FEBG-OAG compared to conventional stereophotographic evaluation of the neuroretinal structures.

The Effect of the Menstrual Cycle on the Optic Nerve Head Analysis of Migrainous Women

PURPOSE

To determine the effect of the menstrual cycle on the optic nerve head topographic analysis of normally menstruating migrainous women.

MATERIAL AND METHODS

Randomly selected one eye of 44 migrainous and 49 healthy control women with regular menstrual cycles were included in the study. All subjects underwent complete ocular examination. Optic nervehead topographic analysis were performed using a confocal scanning laser ophthalmoscope, HRT II (Heidelberg Retinal Tomograph II, software version 1.6;Heidelberg Engineering, Heidelberg, Germany). They were repeated for two times during the menstrual cycle: in follicular phase (7th to 10th day of the cycle) and in the luteal phase (days 3 to 4 before the menstrual bleeding). Serum estradiol, progesterone, and luteinizing hormone measurements were repeated at each menstrual phase.

RESULTS

The mean age of migrainous and control subjects were 31.5 + 5.1 years and 33.4 +/- 3.7 years, respectively (P > 0.05). Their mean disc areas were 2.26 +/- 0.46 mm(2) and 1.95 +/- 0.39 mm(2), respectively(P < 0.05). Control subjects did not demonstrate any difference in the disc topography (P > 0.05). The parameter rim volume decreased, while the parameters cup volume and cup shape measure increased significantly in the luteal phase of the migrainous women (all P values <0.05). Mean intraocular pressure of the migrainous women decreased significantly in luteal phase (P < 0.05).

CONCLUSION

Significant differences exist in the optic rim and cup parameters during the menstrual cycle of the migrainous women. Further clinical trials on ocular blood flow changes during the menstrual cycle of the migrainous women may highlight the role of sex steroids in the optic nerve head of the migrainous women.

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.

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.

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.

Menstrual cycle-dependent differences between right and left visual hemifields in perimetry

PURPOSE

To evaluate the effect of the menstrual cycle and gender on right and left visual hemifields in healthy subjects.

METHODS

One randomly selected eye from each of 42 healthy normally menstruating women and of 37 men with no systemic and ocular problems, other than refractive error, were included in the study. Subjects underwent complete ocular examination and standard acromatic perimetric (SAP) and short-wavelength automated perimetric (SWAP) analysis in both follicular (7th to 10th day of the cycle) and luteal phases (days 3 to 7 before the menstrual bleeding) of the menstrual cycle. Visual field analysis was performed using Model 750 Humphrey Field Analyzer II (Carl Zeiss Meditec, Dublin, CA, USA) with full-threshold, central 30-2 program.

RESULTS

The mean age of female (n = 42) and the male subjects (n = 37) were 35.2 +/- 3.1 years and 34.8 +/- 2.9 years, respectively (p = 0.58). Neither females nor males showed any statistically significant differences in the right and left hemifield tests with SAP (both p values > 0.05). However, using SWAP, in luteal phase of female subjects, left hemifield sensitivity was significantly less than (with a mean of 0.47 dB) right hemifield. In follicular phase, there was no significant interhemifield difference (p > 0.05). Male subjects did not show any significant differences between the sensitivity of the two hemifields with SWAP tests.

CONCLUSIONS

There has been a significant difference between the mean SWAP sensitivity of right and left visual hemifields in luteal phase of the menstrual cycle. In case of a suspected hemifield difference, SAP rather than SWAP may be used to confirm suspected neurological defects as SAP is not affected by the menstrual cycle.

The Prevalence of Glaucomatous Defects With Short-Wavelength Automated Perimetry in Patients With Elevated Intraocular Pressures

PURPOSE

To determine the prevalence of abnormal short-wavelength automated perimetry (SWAP) visual fields in subjects with elevated intraocular pressures (IOP) for 7 existing definitions of mild glaucomatous loss, and to explore the agreement between them.

PATIENTS AND METHODS

Seven hundred and forty-four eyes of 379 subjects with an IOP > or = 22 and < or = 32 mm Hg and normal visual fields with standard automated perimetry (SAP) were tested with SWAP on 3 separate occasions, of which the second and third visual field were used for analysis. The appearance of the optic disc was not an eligibility criterion. We determined the number of visual fields classified as abnormal on 2 successive occasions by 7 existing definitions. In addition, we explored the agreement between the various definitions.

RESULTS

The proportion of eyes with a glaucomatous visual field with SWAP ranged between 0% and 9.9%, depending on the criterion used to define abnormality. A pairwise comparison of the various definitions showed that several definitions classified different eyes as having an abnormal field.

CONCLUSIONS

We found a large variation in the proportion of visual fields with SWAP classified as abnormal by the various definitions. More importantly, various definitions identified different individuals to have an abnormal field with SWAP. Therefore, the diagnostic accuracy and clinical significance of all definitions must be determined before SWAP is used in routine clinical care.

Menstrual Cycle-Dependent Changes in Visual Field Analysis of Healthy Women

PURPOSE

To determine the effect of menstrual cycle phases on the visual field analysis of healthy females.

MATERIAL AND METHODS

One randomly selected eye each of 59 healthy normally menstruating women, and of 54 men with no systemic and ocular problems, other than refractive error, were included in the study. Subjects underwent complete ocular examination, and standard achromatic perimetric (SAP) and short-wavelength automated perimetric (SWAP) analysis in both follicular (7th to 10th day of the cycle) and luteal phases (days 3-7 before the menstrual bleeding) of the menstrual cycle. Visual field analysis was performed using a Model 750 Humphrey Field Analyzer II (Humphrey Instruments Inc., San Leandro, Calif., USA) with full-threshold, central 30-2 program. Visual fields were divided into four regions as superior temporal, inferior temporal, superior nasal and inferior nasal, respectively.

RESULTS

The mean age of female (n = 59) and the male subjects (n = 54) were 34.6 +/- 2.9 and 35.0 +/- 2.7 years, respectively (p = 0.49). SWAP tests demonstrated a significantly decreased mean MS value in the luteal phase (p < 0.05). However, it did not change significantly with SAP tests. Regional MS values of both SAP and SWAP tests were not different in both phases of the menstrual cycle (all p values >0.05). Mean perimetric test durations obtained with both SAP and SWAP were not different throughout the menstrual cycle (both p values >0.05).

CONCLUSION

Clinicians should verify menstrual status when evaluating a suspected loss of visual field sensitivity in menstruating women. The findings of the present study suggest that the SWAP test may be more sensitive to determine subtle sex hormone-dependent changes in visual field analysis of healthy women.

Retinal nerve fiber layer measurement by optical coherence tomography in glaucoma suspects with short-wavelength perimetry abnormalities

PURPOSE

To compare retinal nerve fiber layer (RNFL) measurements in normal and glaucoma subjects with short-wavelength automatic perimetry (SWAP) abnormalities and in chronic primary open-angle glaucoma (CPOAG) patients using optical coherence tomography (OCT).

METHODS

Forty-eight eyes of normal subjects, 34 eyes of glaucoma suspects with SWAP abnormalities, and 38 eyes of early CPOAG subjects were recruited. All normal and glaucoma suspects had normal conventional automated perimetry visual field results. All participants underwent full clinical ophthalmologic evaluation followed by OCT RNFL measurements.

RESULTS

Compared with normal controls, OCT RNFL thickness was significantly lower in glaucoma suspects with abnormal SWAP (inferotemporal and superotemporal thickness values) and CPOAG patients (average, superior, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01). Some parameters were found to be significantly lower in CPOAG patients than the glaucoma suspects with abnormal SWAP (average, inferior, inferotemporal, and superotemporal thickness values) (P < 0.01).

CONCLUSIONS

OCT RNFL measurements appear to correlate well with SWAP abnormalities in glaucoma, and may detect glaucomatous damage earlier than standard conventional automated perimetry. This study suggests that OCT may recognize the earliest evidence of structure alterations in CPOAG.

Recent developments in automated perimetry in glaucoma diagnosis and management

Recently, there have been several new developments in automated perimetry that have contributed to enhanced diagnosis and management of glaucoma. This paper will briefly review four of the latest advances in automated perimetry: (1) efficient test strategies that reduce the testing time and variability of automated perimetric testing, in particular, the Swedish Interactive Threshold Algorithm (SITA) and Tendency Oriented Perimetry (TOP) test strategies will be described; (2) Frequency Doubling Technology (FDT) perimetry, which has been shown to be a rapid, effective method of detecting glaucomatous visual field loss; (3) Short Wavelength Automated Perimetry (SWAP), which has demonstrated the ability to predict the onset and progression of glaucomatous visual field deficits; (4) The Multifocal Electroretinogram (mfERG) and the Multifocal Visual Evoked Potential (mfVEP), which provide an objective measurement of the visual field. Each of these techniques has presented distinct advantages for the diagnosis and management of glaucoma.