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.

Study of patients with ocular hypertension with scanning laser polarimetry and short-wavelength automatic perimetry.

AIMS: To compare and correlate retinal nerve fiber layer (RNFL) measurements obtained by scanning laser polarimetry (SLP) with defects detected by short-wavelength automatic perimetry (SWAP) in eyes with ocular hypertension (OHT). METHODS: SLP and SWAP were performed in 96 eyes of 48 consecutive patients with OHT. RESULTS: Twenty-five eyes (26%) had SWAP visual field defects. Twenty-seven eyes (28.1%) had abnormal RNFL evaluation defined by the GDx neural network ('number' > 29). Fourteen eyes of 10 patients (14.5%) had abnormal RNFL evaluation and SWAP visual field defects. RNFL thickness measurements were significantly reduced in eyes with abnormal SWAP. A weak but statistically significant correlation between the 'number' and pattern standard deviation (r = 0.3, p = 0.006) and the corrected pattern standard deviation (r = 0.3, p = 0.007) in SWAP was found. Areas of abnormal RNFL thickness corresponded to the localization of the SWAP visual field defects in corrected pattern deviation plots in 10 of the 14 eyes with defects in both tests. CONCLUSIONS: SWAP visual field defects frequently coexist and correspond with abnormalities of RNFL detected by SLP in eyes with OHT. In certain eyes, however, the two methods detect different glaucoma properties.