Br J Ophthalmol 1998;82:1007–1012 1007 Br J Ophthalmol: first published as 10.1136/bjo.82.9.1007 on 1 September 1998. Downloaded from Extrafoveal photostress recovery test in glaucoma and idiopathic central serous chorioretinopathy Masayuki Horiguchi, Yasuki Ito, Yozo Miyake Abstract The photostress recovery test (PSRT) meas- Background/aims—A photostress recov- ures the time to recovery of light threshold ery test was designed to diVerentiate after bleaching,1–5 which mainly depends on macular diseases from optic nerve disor- resynthesis of visual pigments. This test has ders, but recently an abnormal recovery been used to evaluate macular function. Previ- time was reported in glaucoma. The ous reports demonstrated prolonged photo- stress recovery times in patients with idiopathic purpose of this study was to search for the 1 diVerence in abnormality of the photo- central serous chorioretinopathy (ICSC), age related macular degeneration,67 diabetic stress recovery test between glaucoma and retinopathy,7 Anandron,8 or digitalis toxicity.9 idiopathic central serous chorioretinopa- Abnormal recovery times in retinal diseases or thy (ICSC). toxicity suggests that the pathology in these Methods—This study involved 21 normal conditions involves the outer layer of the retina subjects, 14 patients, with ICSC and 10 or the pigment epithelium. Optic nerve dis- patients with primary open angle glau- eases can be diVerentiated from retinal diseases coma (POAG). A scanning laser ophthal- with the PSRT,5 because optic nerve dysfunc- moscope (SLO) was used with tion does not aVect the PSRT. However, a pro- microperimetry for bleaching the test longed recovery time,10 11 or delayed dark point and measuring the recovery of adaptation,12–14 were reported in glaucoma, sensitivity. Photostress recovery time which mainly aVects ganglion cells. This (SLO-PSRT) could be measured at extra- suggests that a ganglion cell abnormality may foveal points outside and inside the af- delay recovery or that glaucoma may cause fected area. The initial sensitivity change visual pigment abnormality. and the time constant of recovery after The purpose of this study is to investigate bleaching were calculated by fitting an the diVerence in abnormality of photostress exponential equation to the data. recovery between retinal diseases with aVected photopigment, and glaucoma. ICSC was the —In normal subjects, neither the Results first disease in which PSRT was tested, and in initial sensitivity change nor the time con- this disease a prolonged recovery time and stant were correlated with the location of abnormal kinetics of visual pigment were http://bjo.bmj.com/ the test point. In 14 patients with ICSC, found. Therefore, we tested patients with the initial sensitivity change in the de- ICSC as a model of retinal diseases with tached area was significantly smaller than abnormal visual pigment. that in the unaVected area which was not PSRT can be performed using an acuity significantly diVerent from that in the age chart (conventional PSRT),1–5 a pattern VEP matched normal subjects. The time con- (VEP-PSRT),11 15 16 or a pupillometer (pupil stant in the detached area was signifi- PSRT).17 Conventional and VEP-PSRTs cantly longer than that in the unaVected measure macular function, and pupil PSRT on September 30, 2021 by guest. Protected copyright. area, which was not significantly diVerent tests the central 30° area of the visual field. On from that in the normal subjects. In 10 the other hand, the extrafoveal PSRT tech- patients with POAG, the initial sensitivity nique which we have developed with microper- change inside and outside the scotoma imetry in a scanning laser ophthalmoscope was not significantly diVerent from that of (SLO) (Rodenstock, Germany) can measure the recovery time while monitoring the fundus Department of age matched normal subjects. The time Ophthalmology, constant inside the scotoma was signifi- continuously, and at any points on the TV Nagoya University cantly longer than that outside the monitor of a SLO (SLO-PSRT). Previous School of Medicine, scotoma, which was not significantly dif- reports on the PSRT in glaucoma used Nagoya Japan ferent from that of the age matched conventional and VEP-PSRTs, but defects of M Horiguchi the visual field are often located outside the normal subjects. Y Ito fovea. We tested the points inside and outside Y Miyake —Both ICSC and POAG Conclusion the scotoma, using an extrafoveal PSRT showed a prolonged time constant of Correspondence to: technique. In ICSC, the recovery time was also Masayuki Horiguchi, MD, recovery, but the initial sensitivity change measured inside and outside the detachment Department of was reduced only in ICSC. The diVerence and the results were compared with those in Ophthalmology, Nagoya in our results between ICSC and POAG University School of glaucoma. Medicine, 65 Tsuruma-cho, may be caused by the diVerence of the Showa-ku, Nagoya 466 retinal pathology. Further, the SLO-PSRT Subjects Japan. is very useful when the lesion is located This study involved 21 normal subjects (age Accepted for publication outside the fovea. 40.4 (SD 14.0) years, sex: 10 males and 11 11 March 1998 (Br J Ophthalmol 1998;82:1007–1012) females), 14 patients with ICSC (age 42.7 1008 Horiguchi, Ito, Miyake Br J Ophthalmol: first published as 10.1136/bjo.82.9.1007 on 1 September 1998. Downloaded from epithelium,20 21 patients using this medication were excluded. All patients in POAG group had been followed by one of the authors (MH) for more than a year and the diagnosis was made carefully by routine examinations. None of the normal subjects has a history of chorioretinal disease or colour vision defects, and fundus examination using a SLO and fluo- rescein angiogram revealed no lesions. Methods The SLO-PSRT required an unmodified and commercially available SLO, a Wratten filter (No 21, Eastman Kodak) and a personal com- puter for fitting an equation to the data. The SLO-PSRT was performed in the following manner. After the subjects’ pupils were dilated with a combination of 0.5% tropicamide and 0.5% phenylephrine hydrochloride, the subjective threshold for the red target was measured by microperimetry with a SLO at testing points. The recovery time was defined as the time from the end of bleaching to recognition of the red test spot. The size of the test spot was 0.86 degrees in diameter and the intensity of the background illumination of 10 cd/m2. The test spots, background illumination and a fixating point were all 633 nm in wavelength and stemmed from a He-Ne laser. Therefore, the colour of test targets and background illumina- tion is diVerent from that in conventional or VEP-PSRT, but it does not seem to aVect the results in PSRT. After subjects had dark adapted for 15 min- utes, argon green bleaching illumination (argon green 9), 514 nm in wavelength, and an intensity of 4.7 log cd/m2 was projected onto Figure 1 (A) The image on the fundus monitor of a SLO during extrafoveal bleaching. the fundus for 20 seconds. When we measured The area with stripes was covered with a Wratten filter. A cross indicates a fixating target the recovery time at the extrafoveal points, we http://bjo.bmj.com/ and “A” indicates a testing point. (B) The image of the fundus monitor during foveal only bleached the small area including the test- bleaching. Four crosses indicate fixating targets and “A” indicates a testing point. ing point using a Wratten 21 filter on the (8.2) years, sex: 11 males and three females), instrument window of a SLO, which absorbed and 10 patients with primary open angle glau- all light below the wavelength of 520 nm. The coma (POAG) (age: 48.6 (13.2) years, sex: filter placed on the window was not confocal seven males and five females). All of the with the retina but did not aVect bleaching subjects had little opacity of the crystalline lens light or test spot focused on the retina. The and normal visual acuity. Since aging aVects fovea was left unbleached so that the subjects on September 30, 2021 by guest. Protected copyright. the kinetics of visual pigments, an age matched could see the central fixating point during and control group was selected from 21 normal after bleaching. This filter blocked the bright subjects for glaucoma and ICSC (age 46.6 green illumination (514 nm) bleaching the (18.4) years, sex: three males and seven retina but did not prevent the subjects from females). All subjects in the ICSC group had seeing the red background illumination and macular detachment with one or two leaking the 633 nm fixating point. Figure 1A shows the points seen in fluorescein angiograms. Indo- image on the fundus monitor of a SLO during cyanine green (ICG) angiogram was per- extrafoveal bleaching. The area with stripes formed on all subjects, and revealed abnormal- was covered with a Wratten filter, a cross indi- ity in the choroid as reported previously.18 19 cates a fixating target, and “A” indicates a test- None underwent photocoagulation therapy ing point. When we tested the fovea, we before our examination or had a history of bleached only the central area including the other chorioretinal diseases. The visual acuity fovea, leaving the extrafoveal area unbleached was better than 0.8, and the intraocular by the filter on the instrument window of the pressure was normal. All patients in the POAG SLO. Four fixating points were placed in the group had scotoma in the upper visual field unbleached area. Figure 1B shows the image of (Bjerrum area) and the visual acuity was the fundus during foveal bleaching. The area normal. The intraocular pressure was kept at with stripes was covered with Wratten filters, less than 20 mm Hg with â blocker eyedrops four crosses indicate fixating targets, and “A” only at the time of our testing.