A comparison of short wavelength automated perimetry with frequency doubling perimetry for the early detection of visual field loss in ocular hypertension

Background : Achromatic automated perimetry (AAP) is limited in its ability to detect very early visual field loss in ocular hypertensive patients. Tests targeting axons that are selectively damaged, or have low redundancy, may detect visual field losses before they are seen on AAP. It has been claimed that short wavelength automated perimetry (SWAP) and frequency doubling perimetry (FDP) are two tests that provide early detection. Methods : Patients (n = 62) were selected on the basis that they had raised intraocular pressure but normal visual fields detected by AAP. A SWAP and an FDP was performed on each of the patients and the results compared. Fields were scored as either normal or abnormal based on criteria used in previous studies. Results : On comparing FDP with SWAP as the ‘gold standard’, a sensitivity of 88.9% and a specificity of 96.2% was found, showing a high concordance between the two tests. Conclusion : These results suggest that as SWAP may be predictive of AAP visual field loss, FDP may be similarly predictive.