Comparing the full-threshold and Swedish interactive thresholding algorithms for short-wavelength automated perimetry

SHORT-WAVELENGTH AUTOMATED PERIMETRY IN DIABETIC PATIENTS WITHOUT RETINOPATHY

AIM

To compare the results of short-wavelength automated perimetry (SWAP) in diabetic patients without retinopathy and healthy subjects and show if it is possible to detect an abnormal function of the retina in diabetic patients before vascular changes on the retina develop. Further, the effect of diabetes duration and long-term glycaemic control on the visual field was examined.

METHODS

The study group included 22 patients with diabetes type 1 or 2, without any signs of retinopathy. The control group consisted of 21 healthy subjects. Short-wavelength automated perimetry was performed on the Humphrey Field Analyzer (HFA 860, Carl Zeiss Meditec), SITA SWAP, 24-2 test. In diabetic patients, the duration of diabetes and the level of glycohemoglobin (HbA1c) was registered. The visual field indices MD (mean deviation) and PSD (pattern standard deviation) were compared between both groups by the Mann-Whitney test. The correlation between the visual field indices, HbA1c and duration of diabetes was assessed by the Spearman correlation coefficient.

RESULTS

The mean value of MD in the study and control group was -3.64±3.66 dB and -1.48±2.12 dB respectively, the values in the study group were significantly lower (p < 0.05). Mean PSD in the study group was 2.92±1.04 dB and 2.23±0.33 dB in the control group, again the difference was statistically significant (p < 0.05). Patients in the study group suffered from diabetes for 17±9.4 years in average. The mean value of HbA1c in the study group was 60.64±16.63 mmol/mol. A significant correlation was found only for PSD and HbA1c (p > 0.05). The duration of diabetes had no effect on either of the visual field indices.

CONCLUSION

Short-wavelength sensitivity of retina seems to be affected in diabetic patients without clinically significant retinopathy suggesting a neuroretinal impairment at early stages of the retinopathy. We found no association between the visual field and the control or duration of diabetes.

Structure-Function Relationship in Glaucoma Patients With Parafoveal Versus Peripheral Nasal Scotoma

PURPOSE

We evaluated whether the structure-function relationship in glaucoma patients with parafoveal scotoma or peripheral scotoma differs with the use of frequency doubling technology (FDT) or short-wavelength automated perimetry (SWAP) compared to standard automated perimetry (SAP).

METHODS

Glaucoma patients with isolated parafoveal scotoma (PFS) within the central 10° of fixation in 1 hemifield and those with an isolated peripheral nasal step (PNS) within the nasal periphery outside 10° of fixation in one hemifield were studied. Peripapillary retinal nerve fiber layer (RNFL) thickness was measured using spectral-domain optical coherence tomography. The topographic relationships between structure and function were investigated.

RESULTS

In the PNS group, superotemporal (r(2) = 0.300, P = 0.001) and inferotemporal (r(2) = 0.302, P = 0.001) RNFL thickness showed significant correlations with the corresponding visual field (VF) sensitivity using linear regression model in SAP. In the PFS group, temporal RNFL thickness was not correlated with nasal mean sensitivity (MS) on SAP (r(2) = 0.103, P = 0.065). Using FDT, however, the temporal RNFL thickness was correlated with nasal MS in the PFS group (r(2) = 0.277, P = 0.001). Using SWAP, the temporal RNFL thickness was not significantly associated with regional VF sensitivity in the PFS group (r(2) = 0.052, P = 0.192).

CONCLUSIONS

In glaucoma with peripheral scotoma, the RNFL thickness was associated significantly with the corresponding VF loss in SAP, FDT, and SWAP. In eyes with PFS, however, the topographic structure-function relationships were not distinct with SAP or SWAP. Frequency doubling technology performed well in terms of structure-function correlation in glaucoma with PFS.

Effect of yellow-tinted intraocular lens on standard automated perimetry and short wavelength automated perimetry in patients with glaucoma

Purpose:

To investigate the effect of cataract surgery and yellow-tinted intraocular lens (IOLs) implantation on perimetry indices of short-wavelength automated perimetry (SWAP) and standard automated perimetry (SAP) testing in patients with coexisting cataract and glaucoma.

Materials and Methods:

In this prospective comparative case series, phacoemulsification with implantation of yellow-tinted Acrysof Natural IOL was performed in 16 eyes of 16 patients with visually significant cataract (best-corrected visual acuity (VA) better than 20/120) and mild to moderate glaucoma. Pre- and postoperative values for VA and for perimetry indices including mean deviation (MD), pattern standard deviation (PSD), and foveal threshold (FT) from both SAP and SWAP testing were compared.

Results:

Postoperative VA improved significantly after cataract surgery and yellow-tinted IOL implantation (P < 0.001). After cataract extraction and IOL implantation, MD and FT on SWAP testing improved significantly (P = 0.001); however, there was no statistically significant change with SAP testing between the pre- and postoperative perimetry indices. There was no statistically significant change in PSD with either SAP or SWAP testing postoperatively. The differences between pre- and postoperative values for all perimetry indices under study were not significant when comparing SAP with SWAP tests, except for MD which had improved statistically significantly in SWAP testing (P = 0.03).

Conclusions:

In mild to moderate glaucoma patients with cataracts, the perimetry indices of SWAP testing improved after phacoemulsification and yellow-tinted IOL implantation. This suggests that the yellow-tinted IOLs have less effect on SWAP testing than visually significant cataracts.

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.

Combining functional and structural tests improves the diagnostic accuracy of relevance vector machine classifiers

PURPOSE

To investigate whether combining optic disc topography and short-wavelength automated perimetry (SWAP) data improves the diagnostic accuracy of relevance vector machine (RVM) classifiers for detecting glaucomatous eyes compared with using each test alone.

METHODS

One eye of 144 glaucoma patients and 68 healthy controls from the Diagnostic Innovations in Glaucoma Study were included. RVM were trained and tested with cross-validation on optimized (backward elimination) SWAP features (thresholds plus age; pattern deviation; and total deviation) and on Heidelberg retina tomograph II (HRT) optic disc topography features, independently and in combination. RVM performance was also compared with 2 HRT linear discriminant functions and to SWAP mean deviation and pattern standard deviation. Classifier performance was measured by the area under the receiver operating characteristic curves (AUROCs) generated for each feature set and by the sensitivities at set specificities of 75%, 90%, and 96%.

RESULTS

RVM trained on combined HRT and SWAP thresholds plus age had significantly higher AUROC (0.93) than RVM trained on HRT (0.88) and SWAP (0.76) alone. AUROCs for the SWAP global indices (mean deviation: 0.68; pattern standard deviation: 0.72) offered no advantage over SWAP thresholds plus age, whereas the linear discriminant functions AUROCs were significantly lower than RVM trained on the combined SWAP and HRT feature set and on HRT alone feature set.

CONCLUSIONS

Training RVM on combined optimized HRT and SWAP data improved diagnostic accuracy compared with training on SWAP and HRT parameters alone. Future research may identify other combinations of tests and classifiers that can also improve diagnostic accuracy.

Homonymous hemianopia detected by short wavelength automated perimetry in a patient with normal standard perimetry and MRI

PURPOSE

To report a case of homonymous hemianopia detected by short wavelength automated perimetry (SWAP) in a patient with normal standard automated perimetry (SAP) and magnetic resonance imaging (MRI) of the brain and orbits.

METHODS

A 61-year-old woman with a history of motor vehicle accident with head injury nearly 50 years before presentation was referred for further evaluation as a glaucoma suspect. Complete ophthalmic examination, corneal pachymetry, SAP, SWAP, retinal nerve fiber layer analysis by ocular coherence tomography, and brain and orbital MRI were done.

RESULTS

The patient had intraocular pressure (IOP) of 18-mm Hg and vertical cup-to-disc ratios of 0.8 in each eye. Superior neuroretinal rim pallor was detected in both optic discs on dilated optic nerve examination, and corresponding retinal nerve fiber layer thinning was detected with ocular coherence tomography. SAP indicated minimal nonspecific changes in the right eye, whereas the left eye had a normal visual field. SWAP revealed a left homonymous hemianopia. Neurologic examinations and MRI of the brain and orbits were found to be normal.

CONCLUSIONS

SWAP can detect subtle hemianopic field defects in patients with normal standard perimetry.

Mild learning effect of short-wavelength automated perimetry using SITA program

PURPOSE

To evaluate the learning effect at Short-wavelength Automated Perimetry (SWAP) using the Swedish Interactive Threshold Algorithm (SITA) program over the central 24 degrees on patients with ocular hypertension experienced with standard automated perimetry.

METHODS

Twenty-seven patients underwent 5 SITA SWAP tests at intervals of 5+/-2 days in a randomized eye. Learning effect was defined as an improvement in results for duration, perimetric indices, foveal sensitivity, Glaucoma Hemifield Test, number of points with a P<5% and <1% in the total, and pattern deviation maps, total, central, paracentral, peripheral, and quadrant sensitivity.

RESULTS

Learning effect was shown for foveal sensitivity (P=0.006, analysis of variance), which was significantly different only between the first (23.0 dB+/-4.1 dB) and the last test (24.7 dB+/-3.8 dB, P=0.003, t test) and was not affected by any demographic or ophthalmic characteristics of the population. All the other parameters did not show any significant learning effect.

CONCLUSIONS

SITA SWAP is affected by a small learning effect interfering only with the first test, as opposite to full-threshold SWAP program, which previously showed severe learning artefacts. This fact may induce reconsideration of the clinical utilization of SWAP for the early diagnosis of glaucoma.

African Descent and Glaucoma Evaluation Study (ADAGES): III. Ancestry differences in visual function in healthy eyes

OBJECTIVE

To investigate differences in visual function between the healthy eyes of people of African (AD) and European descent (ED).

METHODS

Visual function was assessed in 393 AD and 367 ED participants selected from the African Descent and Glaucoma Evaluation Study and the Diagnostic Innovations in Glaucoma Study. Participants had normal appearance of the optic disc and intraocular pressure of less than 22 mm Hg. Each participant had 2 reliable 24-2 standard automated perimetry tests, and most had short-wavelength automated perimetry and frequency-doubling technology tests. The generalized estimating equation was used to adjust for intereye correlations. Results were adjusted for age, vertical cup-disc ratio, disc size, central corneal thickness, and presence of high blood pressure.

RESULTS

The AD participants were younger (mean [SD] age, 46.2 [13.2] years) than the ED participants (age, 49.5 [16.6] years) (P = .003). The AD participants had worse mean deviation and pattern standard deviation and more points triggered as abnormal on the total and pattern deviation plots compared with ED participants on all tests (P < .05). A larger percentage of AD participants had confirmed abnormal glaucoma hemifield test results on standard automated perimetry only.

CONCLUSIONS

People of AD have significantly worse performance than people of ED on all tests of visual function. Additional research using longitudinal data is needed to determine the cause of these small but significant ancestry differences in visual function.