Comparison of SWAP and SAP on the point of glaucoma conversion

Abstract

BackgroundThe 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.MethodsIn 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.ResultsOf 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.ConclusionThe 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.

Primary Open-Angle Glaucoma Suspect Preferred Practice Pattern® Guidelines

“…Clinicians may use these selective functional tests to diagnose early visual loss in glaucoma suspects, but studies have not demonstrated clear advantages over standard automated achromatic visual field testing (e.g., SAP). [161][162][163] Optic nerve head and retinal nerve fiber layer imaging The appearance of the optic nerve and, if possible, the RNFL, should be documented for the glaucoma suspect patient. 106,133 (II++, good quality, strong recommendation) Although they are distinctly different methodologies, stereoscopic disc photographs and computerized images of the nerve are complementary with regard to the information they provide the clinician who must manage the patient.…”

How to detect progression in glaucoma

“…Older longitudinal studies suggested that short-wavelength automated perimetry (SWAP, or blue-on-yellow perimetry) could detect visual field deterioration earlier than SAP Demirel and Johnson, 2001;Johnson et al, 1993a,b); however, more recent studies failed to confirm these findings (Havvas et al, 2013;Van der Schoot et al, 2010). Differences in methodology could influence the conflicting findings: earlier studies used custom normative databases and performed individual adjustments by lens opacities, while the most recent studies used the device built-in normative database without lens opacities adjustments.…”

Extended glaucoma diagnostics

“…Standardowa perymetria automatyczna jest powszechnie stosowana w diagnostyce i monitorowaniu neuropatii jaskrowej, a na rynku funkcjonuje wiele różnych typów polomierzy. Jednak nawet rekomendowane przez Europejskie Towarzystwo Jaskrowe i Polskie Towarzystwo Okulistyczne polomierze Humphreya i Octopusa nie są wystarczająco specyficzne i czułe, ponieważ ubytki w polu widzenia są widoczne dopiero po utracie ponad 30% komórek zwojowych [9][10][11]. Komórki zwojowe siatkówki w zależności od wielkości i funkcji dzieli się na komórki drobnokomórkowe (P, parvocellular), pyłkokomórkowe (K, koniocellular), wielkie komórki zwojowe (M, magnocellular) oraz komórki światłoczułe zawierające barwnik melanopsynę [12,13].…”

“…Na wykrywanie ubytków w wielkich komórkach zwojowych jest też nastawiona perymetria detekcji ruchu (MAP, motion automated perimetry), w której tło pokryte jest różnej wielkości kropkami, a pacjent ma za zadanie zaobaczenie i wykrycie ruchu kropek wewnątrz nieruchomego celu [13,15]. Na innej zasadzie działa polomierz typu SWAP (short wavelength automated perimetry), w którym niebieski bodziec na żółtym tle umożliwia detekcję niebieskoczułego szlaku małych komórek zwojowych typu P [9,13].…”

“…Havvas i wsp. [9] w czasie prospektywnych 5-letnich obserwacji wykonywali badania za pomocą polomierzy SWAP i SAP u pacjentów z nadciśnieniem ocznym. Do programu początkowo zrekrutowano 282 pacjentów, z których 32 z różnych przyczyn zostało wyłączonych.…”