Enhanced S-Cone Syndrome (Goldmann-Favre Syndrome)

In enhanced S-cone syndrome (ESCS), rods and red and green cone receptors are degenerated, but S-cones are enhanced (increased in number). Patients have increased sensitivity to blue light, with night blindness from an early age (from birth) and impaired central vision. The fundus shows characteristic nummular pigmentary changes along the vascular arcades at the level of the retinal pigment epithelium (RPE). (In retinitis pigmentosa [RP], pigment is deposited within the retina.) Sometimes, there are white-yellow dots at the level of the RPE along the vascular arcades, along with focal hyperpigmentation within the arcades (Figs. 28.1 and 28.2). Patients may also have foveal schisis. (Goldmann-Favre syndrome consists of foveal schisis plus peripheral degeneration.) Fundus autofluorescence (FAF) shows a decrease or lack of AF outside the arcades, possibly due to loss of photoreceptors in this region; a ring of hyperautofluorescence (hyperAF) is seen in the transition zone between the region of absent AF beyond the arcade and the central zone of spoke-like, relatively increased AF, centered on the fovea; increased AF may be related to lipofuscin accumulation secondary to RPE-photoreceptor dysfunction in that area. Electroretinograms (ERGs) in ESCS are pathognomonic and show extinguished rod response and a similar wave form in both scotopic and photopic conditions. The 30 Hz flicker responses are markedly delayed and are of lower amplitude. (Normally, flicker amplitude lies between that of the photopic a- and b-waves, but in ESCS, it is less than that of the photopic a-wave.) With orange background (suppressing red and green cones), increased response to short wavelength (blue) is elicited, suggestive of functioning of S-cones. The multifocal ERG (mfERG) shows preservation of central responses, though somewhat delayed. ESCS is a slowly progressive disorder that often leads to severe visual loss in adults.