Selective reduction of the S-cone component of the electroretinogram in Posner-Schlossman syndrome

Purpose The changes in short wavelength sensitive (S-) cone electroretinograms (ERGs) to ganzfeldt flash stimuli were examined in patients with Posner-Schlossman syndrome to study the differences in S-cone action in both the acute attack phase and the remission phase. Methods Ganzfeldt colour flashes under bright white background illumination were used to elicit short wavelength (S-), and mixed long- (L) and middle- (M) wavelength sensitive cone ERGs. Three subjects with unilateral Posner-Schlossman syndrome and 18 age-matched normal controls were compared. To compare the media opacity we obtained the L,M-cone balance, namely, the log density units of the neutral density filter required to produce the L,M-cone b-wave elicited with red stimuli which is identical to those with blue stimuli. Results Selective reduction of the S-cone ERG b-wave in acute attacks of Posner-Schlossman syndrome was found. Two of three cases showed the recovery of the S-cone b-wave with a decrease in the intraocular pressure. With regard to the implicit time, significant delay of the S-cone b-wave could not be detected in all subjects. Conclusion Selective reduction of the S-cone component of the ERG during raised intraocular pressure was found. The S-cone pathway is thought to be more vulnerable to damage than the L,M-cone systems following elevations of intraocular pressure.