The Efficacy of Transcorneal Electrical Stimulation for the Treatment of Primary Open-angle Glaucoma: A Pilot Study.

The aim of this study was to evaluate the effects of transcorneal electrical stimulation in subjects with primary open-angle glaucoma. Five eyes of four male subjects with primary open-angle glaucoma (average age: 52.25 ± 14.68 years) were enrolled. The subjects underwent transcorneal electrical stimulation every 3 months according to the following procedure. A Dawson-Trick-Litzkow electrode was placed on the cornea, and biphasic electric current pulses (10 ms, 20 Hz) were delivered using a stimulator (BPG-1,BAK Electronics) and a stimulus isolation unit (BSI-2). A current that evoked a phosphene that the subject perceived in the whole visual area was delivered continuously for 30 min. Humphrey visual field testing was performed after every third transcorneal electrical stimulation treatment. Changes in mean deviation (MD) values were evaluated with a linear regression model. Transcorneal electrical stimulation was performed 18.2 ± 9.4 times over a period of 49.8 ± 23.0 months. The average pretranscorneal electrical stimulation intraocular pressure, best corrected visual acuity, and MD values were 11.8 ± 1.79 mmHg, 0.14 ± 0.19 (logMAR) and -17.28 ± 6.24 dB, respectively. No significant differences were observed in intraocular pressure before and after transcorneal electrical stimulation. However, there was a significant positive linear relationship between changes in MD values and the number of transcorneal electrical stimulation treatments (R2 = 0.176, P = 0.005, Spearman correlation R =0.294, P = 0.008). Transcorneal electrical stimulation treatment may improve glaucomatous visual field defects in subjects with primary open-angle glaucoma. Large-scale studies are necessary to confirm these preliminary findings.

Improvement of visual acuity after transcorneal electrical stimulation in case of Best vitelliform macular dystrophy.

PURPOSE: To report an improvement of the visual acuity after transcorneal electrical stimulation (TES) in a case of Best vitelliform macular dystrophy (BVMD). PATIENT AND METHODS: A 26-year-old woman diagnosed with BVMD presented with reduced vision. Her best corrected visual acuity (BCVA) was reduced to 20/200 in the right eye, and TES was performed once a month for two sessions. The current of the biphasic pulses (anodic first; duration, 10 msec; frequency, 20 Hz) was delivered using a DTL-electrode, and the duration of the TES was 30 min. RESULTS: The BCVA in the right eye slowly improved after the TES, and 6 months later the BCVA was 20/25. The results of Humphrey visual field tests (VF) and multifocal ERGs (mfERGs) were only slightly changed. Two years later, the BCVA decreased, and it was improved again after another session of TES with the same parameters of the electrical pulses. CONCLUSION: The improvement of the visual acuity in our case of BVMD indicates that TES should be tried in other cases of retinal dystrophy. Further clinical and laboratory studies on TES are needed.

Mechanism of visual sensations experienced during pars plana vitrectomy under retrobulbar anesthesia.

PURPOSE: To investigate the visual sensations experienced by patients during vitrectomy under retrobulbar anesthesia. METHODS: 30 men and 45 women with a mean age of 65.3 +/- 10.6 years underwent vitrectomy under retrobulbar anesthesia for macular disease. 28 eyes had an idiopathic epiretinal membrane, 13 had an idiopathic macular hole, 32 had macular edema (17 diabetic retinopathy and 15 retinal vein occlusion), and 2 had submacular hemorrhage. 49 patients with nonmacular disease underwent similar vitrectomy procedures and were used for comparison. An interview was conducted with the patient about his/her visual sensations during and within 3 h of the vitrectomy. RESULTS: 70 (93.3%) of the patients reported seeing lights, 53 (70.7%) reported seeing colors, and 48 (64.0%) reported seeing movements or moving objects. Of the patients who reported seeing movements or moving objects, 44 (58.7%) reported seeing surgical instruments, and 5 (6.7%) saw the surgeon's fingers or hands. Patients with macular diseases tended to report more visual sensations than patients with nonmacular diseases. The patients' description and drawings appeared to arise mainly from the shadows cast by the intravitreal objects, and some patients perceived highly accurate details including the movements and color of the objects. CONCLUSIONS: Visual sensations are experienced by approximately 90% of the patients, and there may be a common mechanism by which patients perceive the intravitreal objects that are not focused on by the retina through the eye's optical system.

Patients' descriptions of visual sensations during pars plana vitrectomy under retrobulbar anesthesia.

PURPOSE: To investigate the visual sensations experienced by patients during vitrectomy under retrobulbar anesthesia. DESIGN: Cross-sectional study. METHODS: Fifty-six men and 45 women with a mean age of 62.2 +/- 11.9 years (range, 30 to 89 years) were studied. Twenty-two eyes had an idiopathic epiretinal membrane, 10 had an idiopathic macular hole, 29 had macular edema (16 resulting from diabetic retinopathy and 13 resulting from retinal vein occlusion), 14 had proliferative diabetic retinopathy, 13 had rhegmatogenous retinal detachment, four had proliferative vitreoretinopathy, and nine had other retinal diseases. The patients were questioned about their visual sensations during and within three hours after vitrectomy, which was performed under retrobulbar anesthesia using 2% lidocaine hydrochloride. Visual sensations perceived by the patients during surgery were reviewed. RESULTS: Ninety-one of the 101 patients experienced some type of visual sensation during the vitrectomy. Ninety-one (90.1%) patients reported seeing lights, 73 (72.3%) patients reported seeing one or more colors, and 57 (56.4%) patients reported seeing movements or moving objects. Of these latter 57 patients, 54 saw instruments and nine (8.9%) saw the surgeon's fingers or hands. In the 94 cases that had triamcinolone-assisted vitrectomy, 35 (37.2%) reported seeing many diffuse whirling black spots. Six patients (5.9%) found the visual experiences frightening. CONCLUSIONS: Visual sensations are experienced by approximately 90% of the patients despite full pain control, and surgeons should warn patients of these possibilities because they can be frightening. This should minimize patients' anxiety and stress during the surgery.

Transcorneal electrical stimulation of retina to treat longstanding retinal artery occlusion.

PURPOSE: To report the outcome of transcorneal electrical stimulation (TES) of the visual system on long-standing retinal artery occlusion (RAO). DESIGN: Open labeled, case series. PATIENTS AND METHODS: Two patients with central RAO (15 and 33 months respectively) and one with branch RAO (26 months) underwent TES therapy. Subjective and objective ophthalmological evaluations were performed before and after the TES. The ages of the patients were 38, 49, and 63 years. The TES (20 Hz biphasic pulses, 30 minutes, up to 1100 uA) was delivered by a bipolar contact lens electrode once a month for 3 months. Perimetric and/or electrophysiological examinations were performed as outcome measures. RESULTS: The visual acuity improved by more than 0.2 logMAR units in two cases, and the visual fields were improved in all three cases. The multifocal ERGs which had been reduced in the loci corresponding to the ischemic retinal area were improved after the treatment in two cases. Neither ocular nor systemic adverse effects were observed except for transient superficial keratitis. CONCLUSIONS: TES of the retina can improve retinal function in eyes with long-standing RAOs.

Subjective visual sensation during vitrectomy under retrobulbar anesthesia.

PURPOSE: To report a precise illustrated image of patient's view during vitrectomy. DESIGN: Interventional case report. METHODS: A 56-year-old male with cystoid macular edema (CME) associated with epiretinal membrane underwent vitrectomy. The patient seemed to find gratification in being operated on because he was able to see what was going on. He was a professional artist in computer graphics, and he drew three different pictures depending on the surgical procedures. RESULTS: These pictures depicted the moving of pasty, whirling fluid during core vitrectomy, numerous black or gray spots like snowflakes by intravitrealy injected crystals of triamcinolone acetonide, and a sharp tapered instrument coming into the center and membrane-like material being peeled off. CONCLUSIONS: Patients may see a precise shape in a constant size, scale, and detailed movement as well, focused on the retina without described optics. Further investigation will be required to determine this mechanism.

In vivo assessment of subretinally implanted microphotodiode arrays in cats by optical coherence tomography and fluorescein angiography.

BACKGROUND: Following multiple promising investigations into restoration of vision in degenerative retinal disease by implantation of a sub- or epiretinal prosthesis, the step to clinical use in humans is impending. In this study we intended to establish optical coherence tomography (OCT) and fluorescein angiography (FA) first in research animals for noninvasive assessment of the condition of the posterior pole of eyes after intraocular implant surgery. METHODS: Three adult cats that had undergone subretinal implant surgery were evaluated by OCT and FA between 1 and 470 days postoperatively. Eight adult cats served as control. In addition histology was performed. RESULTS: In all three cats OCT demonstrated stable positioning of the implants in the subretinal space during the complete examination period. Transient retinal edema was found in the early postoperative period but decreased during follow-up. The retina over the implants was well attached at all times in cats 1 and 2; however, in cat 3 localized retinal detachment was demonstrated. FA showed intact retinal vasculature over the subretinal implant in high detail without interference from choroidal background fluorescence. CONCLUSIONS: OCT and FA have been fruitfully applied to cats to assess the morphological and circulatory conditions of the neuroretina and of its interface with the subretinal implant. The techniques may therefore provide a tool for objective, noninvasive in vivo evaluation of eyes that have undergone subretinal implant surgery, both in research animals and in humans.