Supervised dichoptic gaming versus monitored occlusion therapy for childhood amblyopia: Effectiveness and efficiency.

PURPOSE: To compare the effectiveness and efficiency of supervised dichoptic action-videogame play to occlusion therapy in children with amblyopia. METHODS: Newly diagnosed children with amblyopia aged 4-12 years were recruited, excluding strabismus >30PD. After 16 weeks of refractive adaptation children were randomized to gaming 1 h/week supervised by the researcher, or electronically monitored occlusion 2 h/day. The gaming group played a dichoptic action-videogame using virtual reality goggles, which included the task of catching a snowflake presented intermittently to the amblyopic eye. Contrast for the fellow eye was self-adjusted until 2 identical images were perceived. The primary outcome was visual acuity (VA) change from baseline to 24 weeks. RESULTS: We recruited 96 children, 29 declined and 2 were excluded for language or legal issues. After refractive adaptation, 24 of the remaining 65 no longer met the inclusion criteria for amblyopia, and 8 dropped out. Of 16 children treated with gaming, 7 (6.7 years) completed treatment, whereas 9 younger children (5.3 years) did not. Of 17 treated with occlusion, 14 (5.1 years) completed treatment and 3 (4.5 years) did not. Of 5 children with small-angle strabismus, 3 treated with occlusion completed treatment and 2 treated with gaming did not. Median VA improved by 0.30 logMAR (IQR 0.20-0.40) after gaming, 0.20 logMAR (0.00-0.30) after occlusion (p = 0.823). Treatment efficiency was 1.25 logMAR/100 h (range 0.42-2.08) with gaming, 0.08 (-0.19-0.68) with occlusion (p < 0.001). CONCLUSION: Dichoptic gaming seems a viable alternative for older children with refractive amblyopia after glasses adaptation. Treatment efficiency with gaming under continuous supervision was 15 times higher than with occlusion at home.

EEG changes as an indication of central nervous system involvement following cyclopentolate 1% eye drops; a randomized placebo-controlled pilot study in a pediatric population.

To compare EEG-patterns after instillation of cyclopentolate versus placebo eye drops. Prospective, randomized, placebo-controlled, and observational pilot study is presented. Ophthalmology outpatient clinic Dutch metropolitan hospital. Healthy 6- to 15-year-old volunteers with normal or low BMI requiring a cycloplegic refraction/retinoscopy. Randomized; 1 visit 2 drops cyclopentolate-1% and 1 visit 2 drops placebo (saline-0.9%). Single-blind: conducting researcher. Double blind: subjects, parents, clinical-neurophysiology staff, neurologist, and statistician. A 10-min baseline EEG-recording, drop-application, and follow-up to at least 45 min. Primary outcome: Detection of CNS changes, i.e. EEG-pattern changes, following two drops of cyclopentolate-1%. Secondary outcome: Determination of the extent of these pattern changes. Thirty-six cyclopentolate-1% saline-0.9% EEG registrations were made in 33 subjects; 18 males and 15 females. Three subjects were tested twice (interval 7 months). Nine out of fourteen (64%) of the 11- to 15-year-old children reported impaired memory, attention, alertness, as well as mind wandering following cyclopentolate. Drowsiness and sleep were seen in EEG-recordings of 11 subjects (33%) following cyclopentolate. We observed no drowsiness nor sleep during placebo recordings. The mean time to drowsiness was 23 min. Nine subjects arrived in stage-3 sleep but none arrived in REM-sleep. In subjects without sleep (N=24), significant changes compared to placebo-EEG were present for many leads and parameters. The main findings during awake eye-open recording were as follows: 1) a significant increase of temporal Beta-1,2 and 3-power, and 2) a significant decrease in: a) the parietal and occipital Alpha-2-power, b) the frontal Delta-1-power, c) the frontal total power, and d) the occipital and parietal activation synchrony index. The former finding reflects cyclopentolate uptake in the CNS, and the latter findings provide evidence for CNS suppression. Cyclopentolate-1% eye drops can affect the CNS and may cause altered consciousness, drowsiness, and sleep with concomitant EEG results in both young children and children in puberty. There is evidence that cyclopentolate has the potency to act as a short acting CNS depressant. Nevertheless, however, cyclopentolate-1% can safely be used in children and young adolescents.

Safety, effectiveness, and cost-effectiveness of immediate versus delayed sequential bilateral cataract surgery in the Netherlands (BICAT-NL study): a multicentre, non-inferiority, randomised controlled trial.

BACKGROUND: In an ageing population, efficiency improvements are required to assure future accessibility of cataract care. We aim to address remaining knowledge gaps by evaluating the safety, effectiveness, and cost-effectiveness of immediate sequential bilateral cataract surgery (ISBCS) versus delayed sequential bilateral cataract surgery (DSBCS). We hypothesised that ISBCS is non-inferior to DSBCS, regarding safety and effectiveness, and being superior in cost-effectiveness. METHODS: We did a multicentre, non-inferiority, randomised controlled trial, which included participants from ten Dutch hospitals. Eligible participants were 18 years or older, underwent expected uncomplicated surgery, and had no increased risk of endophthalmitis or refractive surprise. Participants were randomly assigned (1:1) to either the ISBCS (intervention) group or DSBCS (conventional procedure) group, using a web-based system stratified by centre and axial length. Participants and outcome assessors were not masked to the treatment groups because of the nature of the intervention. The primary outcome was the proportion of second eyes with a target refractive outcome of 1·0 dioptre (D) or less 4 weeks postoperatively, with a non-inferiority margin of -5% for ISBCS versus DSBCS. For the trial-based economic evaluation, the primary endpoint was the incremental societal costs per quality-adjusted life-year. All analyses were done by a modified intention-to-treat principle. Costs were calculated by multiplying volumes of resource use with unit cost prices and converted to 2020 Euros (€) and US$. This study was registered with ClinicalTrials.gov, number NCT03400124, and is now closed for recruitment. FINDINGS: Between Sept 4, 2018, and July 10, 2020, a total of 865 patients were randomly assigned to either the ISBCS group (427 [49%] patients; 854 eyes) or DSBCS group (438 [51%] patients; 876 eyes). In the modified intention-to-treat analysis, the proportion of second eyes with a target refraction of 1·0 D or less was 97% (404 of 417 patients) in the ISBCS group versus 98% (407 of 417) in the DSBCS group. The percentage difference was -1% (90% CI -3 to 1; p=0·526), thereby establishing non-inferiority for ISBCS compared with DSBCS. Endophthalmitis was not observed or reported in either group. Adverse events were comparable between groups, with only a significant difference in disturbing anisometropia (p=0·0001). Societal costs were €403 (US$507) lower with ISBCS than with DSBCS. The cost-effectiveness probability of ISBCS versus DSBCS was 100% across the willingness-to-pay range of €2500-80 000 (US$3145-100 629) per quality-adjusted life-year. INTERPRETATION: Our results showed non-inferiority of ISBCS versus DSBCS regarding effectiveness outcomes, comparable safety, and superior cost-effectiveness of ISBCS. National cost savings could amount to €27·4 million (US$34·5 million) annually, advocating for ISBCS if strict inclusion criteria are applied. FUNDING: Research grant from The Netherlands Organization for Health Research and Development (ZonMw) and Dutch Ophthalmological Society.

Eye colour and skin pigmentation as significant factors for refractive outcome and residual accommodation in hypermetropic children: a randomized clinical trial using cyclopentolate 1% and tropicamide 1.

PURPOSE: To compare the refractive outcome and residual accommodation with respect to various degrees of iris and skin pigmentation in hypermetropic children using 2 drops of cyclopentolate 1% (C + C) or 1 drop of cyclopentolate 1% and 1 drop of tropicamide 1% (C + T). METHODS: Two hundred fifty-one hypermetropic children were classified according to iris and skin pigmentation (light, medium, dark) and received randomized and double-blind C + C or C + T. Refractive error (spherical equivalent, SEQ) was determined using the Retinomax-K + 3. In 204 subjects, residual accommodation (RA) was determined using the PlusoptiX PowerRefractor. RESULTS: A linear mixed model with a light-irided and light skin-pigmented reference group receiving C + T (mean SEQ +3.10 ± 1.87D) indicated significant less hypermetropia in subjects with a dark iris having a medium- and dark-pigmented skin in C + T, -1.02 ± 0.29 (-1.59/-0.45) and -1.53 ± 0.30 (-2.10/-0.95); and in subjects having a light-, medium- and dark-pigmented skin in C + C, -0.74 ± 0.34 (-1.41/-0.06), -1.26 ± 0.30 (-1.85/-0.66) and -1.84 ± 0.30 (-2.42/-1.26). Similar findings were present for RA. Our model with a light-irided and light skin-pigmented reference group receiving C + T (mean RA +0.84 ± 0.61D) indicated significantly higher RA in dark-irided subjects with medium- and dark-pigmented skin in C + T, +1.05 ± 0.19 (+0.67/+1.43) and +1.35 ± 0.20 (+0.9/+1.74), and in C + C, +1.13 ± 0.21 (+0.71/+1.55) and +1.90 ± 0.19 (+1.51/+2.28). CONCLUSIONS: We found solid evidence that skin pigmentation rather than iris pigmentation is the decisive factor for effectiveness of cycloplegics. Awareness of the limitations of cycloplegic regimens in dark-irided/pigmented children is needed. Our study showed that cyclopentolate 1% combined with tropicamide 1% provides more accurate refractive outcomes both statistically and clinically integrating the factor skin pigmentation for dark-irided subjects.

Performance of the Prototype NovioSense Noninvasive Biosensor for Tear Glucose in Type 1 Diabetes.

INTRODUCTION: We recently published the results of a pilot study measuring glucose in tear fluid. We now show the results of an additional 24 patients. METHODS: Twenty-four subjects were recruited from Haaglanden Diabetes Centre. The patients reported in a fasting state and were given a meal with half the usual dose of insulin during the test. The device was applied under the lower eyelid. Glucose levels from capillary blood and interstitial fluid with a flash glucose measurement device were recorded every 15 minutes; the current from the tear glucose sensor was recorded continuously. The eye surface and tolerability were regularly checked. A calibration algorithm to convert tear glucose to blood values was built using a neural network regression model and validated. RESULTS: No adverse events were attributed to the sensor coil placed under the lower eyelid. The mean absolute relative difference for the 24-patient subset was 16.7 (after 6 hours total time in the eye). The median absolute relative difference was 13.3. Compared to published data from Abbott (15.7 on day 1), the present device is comparable to Libre, considering that the device was allowed only one hour of equilibration time before the measurements were made. CONCLUSION: The NovioSense Tear glucose sensor measures blood glucose values with an acceptable accuracy and may become a good alternative to invasive devices.

A randomized clinical trial using atropine, cyclopentolate, and tropicamide to compare refractive outcome in hypermetropic children with a dark iris; skin pigmentation and crying as significant factors for hypermetropic outcome.

Purpose: To evaluate the refractive outcome and influencing factors following atropine 0.5% eye-drops applied twice daily during 2 ½ days at home and two drops of cyclopentolate 1% (C+C) and one drop of cyclopentolate 1% and one drop of tropicamide 1% (C+T) applied in an outpatient clinic, in hypermetropic children with a dark iris. Methods: Double-blind randomized study including 67 3-6-year-old children receiving C+C in one eye and C+T in the other eye. Two weeks later followed by atropine 0.5% in both eyes. Primary outcome measures were: spherical equivalent (SEQ) following C+C, C+T and atropine, and secondarily SEQ with respect to sex, ethnicity, skin pigmentation (light, medium, dark) and crying. Data on atropine are divided in those with C+C (CC) or C+T (CT) as a first intervention. Results: Mean SEQ±SD for C+C, C+T, atropine-(CC) and atropine-(CT) was +1.74 ± 1.35, +1.77 ± 1.34, +2.15 ± 1.43 and +2.10 ± 1.38 diopter (D). Atropine 0.5% revealed significantly more hypermetropia than C+C and C+T; +0.41 ± 0.43, 95%CI +0.31 to +0.52D and +0.33 ± 0.39, 95%CI +0.24 to +0.34D. No significant difference was present between C+C and C+T; -0.03 ± 0.56, 95%CI -0.16 to +0.11D. Ethnicity and skin-color were strongly associated (r = 0.84, p < .001). Sex was not affecting outcomes (p = .101). Ethnicity was borderline significant (p = .049). Skin-color was a highly significant factor (p = .002). A statistical model combining intervention and skin-color, with light-pigmented subjects receiving atropine-(CC) as reference group (mean SEQ +2.61 ± 1.46D), indicated borderline significantly less hypermetropia in atropine-(CC)-dark: mean decrease (95%CI): -0.81 (-1.66 to +0.05)D and atropine-(CT)-dark -0.87 (-1.70 to -0.03)D, furthermore significantly less hypermetropia in C+C-dark: -1.15 (-1.97 to -0.32)D; C+T-dark: -1.21 (-2.03 to -0.39)D, C+C-medium: -1.02 (-1.81 to -0.24)D and C+T-medium: -0.86 (-1.64 to -0.08)D. Adding crying to the model significantly less hypermetropia was found for subjects crying in all interventions; -0.53 (-0.98 to -0.09)D. Within the interventions, with light-pigmented non-crying subjects as reference group (mean SEQ in atropine, C+C, respectively, C+T: +2.62 ± 1.41, +2.33 ± 1.20 and +2.32 ± 1.20D), showed significantly less hypermetropia in dark-pigmented crying subjects in each individual intervention: atropine -1.10 (-2.01 to -0.19), C+C -1.28 (-2.14 to -0.42) and C+T -1.34 (-2.20 to -0.48)D. For medium pigmented crying subjects this was present in atropine: -0.82 (-1.61 to -0.03)D and C+C: -0.86 (-1.68 to -0.04)D, but not in C+T: -0.58 (-1.25 to +0.09)D. Conclusions: Atropine 0.5% revealed a slight significantly higher hypermetropia. A dark-pigmented skin, especially when crying upon application, resulted in lower hypermetropia in all interventions. C+T provided clinically better results in medium pigmented crying subjects compared to C+C, and equal results compared to atropine 0.5%.

Refractive adaptation and efficacy of occlusion therapy in untreated amblyopic patients aged 12 to 40 years.

PURPOSE: Since neurophysiological and clinical trials have shown evidence for plasticity in the adult visual system, the upper age limit for amblyopia treatment is not rigid. The aim of this study was to investigate the efficacy of occlusion therapy and refractive adaptation in untreated amblyopic patients 12 to 40 years of age. METHODS: In a prospective study, all patients had full orthoptic and ophthalmic assessment including cycloplegic retinoscopy. Patients with a newly prescribed optical correction underwent an 18-week refractive adaptation. All patients were treated with occlusion for 3 h a day for 18 weeks. Acuity gain and responder rates (≥ 0.2 log units) were calculated. The rate of recurrence (visual acuity 9 months after end of the occlusion therapy; ≥ 0.2 log units) and the acuity gain after refractive adaptation were determined. Self-reported compliance to occlusion therapy was assessed. RESULTS: Median age of patients (n = 24) was 32.4 years (IQR 19.2). Best corrected visual acuity at start of occlusion therapy was 0.35 logMAR (IQR 0.5) and 0.30 (IQR 0.4) logMAR at the end of occlusion therapy, an acuity gain of 0.05 logMAR (P = 0.004). Six (25%) patients had an acuity gain of at least 0.2 logMAR units. Reading acuity was improved from 0.4 logMAR (IQR 0.4) to 0.3 logMAR (IQR 0.4) (P = 0.004). Visual acuity was stable 9 months after occlusion therapy. The acuity gain after 18 weeks of refractive adaptation was 0.05 logMAR (P = 0.238, n = 8). Acuity gain by correcting refractive errors was 0.25 logMAR (P = 0.006). Twenty-one (92%) of 24 patients achieved full recording in the calendar. Overall compliance was 17% (IQR 38). Only 5 out of 22 (23%) had acceptable compliance (≥ 50%) to occlusion therapy. Improvement of visual acuity was significantly better in patients with at least 50% compliance (P = 0.013). Compliance was worse in non-native patients than in native patients (P = 0.022). CONCLUSIONS: In adulthood, compliance to occlusion therapy is even more challenging than in children. Noncompliance is the main reason for treatment failure. Only a few patients with acceptable compliance to occlusion therapy had a small but significant improvement of visual acuity. The results suggest that some adults with amblyopia retain a degree of cortical plasticity. We found that untreated adult amblyopic patients did not wear optical correction on the amblyopic eye. The highest treatment benefit was achieved by correcting refractive errors prior to following period of refractive adaptation.

Clinical Evidence for Use of a Noninvasive Biosensor for Tear Glucose as an Alternative to Painful Finger-Prick for Diabetes Management Utilizing a Biopolymer Coating.

Diabetes is a metabolic condition that is exponentially increasing worldwide. Current monitoring methods for diabetes are invasive, painful, and expensive. Herein, we present the first multipatient clinical trial that demonstrates clearly that tear fluid may be a valuable marker for systemic glucose measurements. The NovioSense Glucose Sensor, worn under the lower eye lid (inferior conjunctival fornix), is reported to continuously measure glucose levels in the basal tear fluid with good correlation to blood glucose values, showing clear clinical feasibility in both animals and humans. Furthermore, the polysaccharide coated device previously reported by our laboratory when worn, does not induce pain or irritation. In a phase II clinical trial, six patients with type 1 Diabetes Mellitus were enrolled and the capability of the device to measure glucose in the tear fluid was evaluated. The NovioSense Glucose Sensor gives a stable signal and the results correlate well to blood glucose values obtained from finger-prick measurements determined by consensus error grid analysis.

Randomized controlled European multicenter trial on the prevention of cystoid macular edema after cataract surgery in diabetics: ESCRS PREMED Study Report 2.

PURPOSE: To compare the efficacy of perioperative treatment strategies, in addition to topical bromfenac 0.09% and dexamethasone 0.1%, to reduce the risk for developing cystoid macular edema (CME) after uneventful cataract surgery in diabetic patients. SETTING: Twelve European study centers. DESIGN: Randomized clinical trial. METHODS: Diabetic patients having phacoemulsification cataract surgery were randomly allocated to receive no additional treatment, a subconjunctival injection with 40 mg triamcinolone acetonide, an intravitreal injection with 1.25 mg bevacizumab, or a combination of both. The main outcomes were the difference in central subfield mean macular thickness, corrected distance visual acuity, and the incidence of CME and clinically significant macular edema within 6 and 12 weeks postoperatively. RESULTS: The study comprised 213 patients. At 6 and 12 weeks postoperatively, the central subfield mean macular thickness was 12.3 µm and 9.7 µm lower, respectively, in patients who received subconjunctival triamcinolone acetonide than patients who did not (P = .007 and P = .014, respectively). No patient who received subconjunctival triamcinolone acetonide developed CME. Intravitreal bevacizumab had no significant effect on macular thickness. CONCLUSIONS: Diabetic patients who received a subconjunctival injection with triamcinolone acetonide at the end of cataract surgery had a lower macular thickness and macular volume at 6 and 12 weeks postoperatively than patients who did not. Intravitreal bevacizumab had no significant effect.

European multicenter trial of the prevention of cystoid macular edema after cataract surgery in nondiabetics: ESCRS PREMED study report 1.

PURPOSE: To compare the efficacy of a topical nonsteroidal antiinflammatory drug, topical corticosteroid, and a combination of both drugs to prevent the occurrence of cystoid macular edema (CME) after cataract surgery in nondiabetic patients. SETTING: Twelve European study centers. DESIGN: Randomized clinical trial. METHODS: Nondiabetic patients having uneventful cataract surgery were included in this study. Patients were randomized to receive topical bromfenac 0.09% twice daily for 2 weeks or dexamethasone 0.1% 4 times daily with 1 drop less per day every following week, or a combination of both. The primary outcome was the difference in central subfield mean macular thickness 6 weeks postoperatively. Secondary outcome measures included corrected distance visual acuity as well as the incidence of CME and clinically significant macular edema (CSME) within 6 weeks and 12 weeks postoperatively. RESULTS: This study comprised 914 patients. Six weeks postoperatively, the central subfield mean macular thickness was 288.3 µm, 296.0 µm, and 284.5 µm in the bromfenac group, dexamethasone group, and combination treatment group, respectively (overall P = .006). The incidence of clinically significant macular edema within 12 weeks postoperatively was 3.6%, 5.1%, and 1.5%, respectively (overall P = .043). CONCLUSION: Patients treated with a combination of topical bromfenac 0.09% and dexamethasone 0.1% had a lower risk for developing CSME after cataract surgery than patients treated with a single drug.

Adverse reactions following routine anticholinergic eye drops in a paediatric population: an observational cohort study.

OBJECTIVES: To investigate the presence, nature and relationship to age, sex, ethnicity and body mass index (BMI) of adverse reactions following routine cycloplegic eye drops in children. DESIGN: Prospective observational cohort study. SETTING: Ophthalmology outpatient clinic Dutch metropolitan hospital; February, March and April 2009. PARTICIPANTS: Children aged 3-14-year-old children receiving two drops of cyclopentolate 1% (C+C) or one drop of cyclopentolate 1% and one drop of tropicamide 1% (C+T). Patients were categorised by age (3-6, 7-10 and 11-14 years), sex, ethnicity and body mass index (BMI) (low, normal or high). OUTCOME MEASURES: Rate and nature of adverse reactions reported at 45 min following treatment. Crude and adjusted ORs for reporting an adverse reaction using stepwise regression analysis with BMI, age, ethnicity and sex. RESULTS: 912 of 915 eligible patients participated (99.7%). Adverse reactions were reported for C+C in 10.3% and in C+T in 4.8% (42/408 and 24/504, p=0.002), respectively. Central effects were present in 95% in C+C and in 92% in C+T. Compared to C+T, an increased risk was present in C+C (crude OR 2.3 (1.4 to 3.9), p=0.002). Forward adjustment showed BMI to be an influencing factor in treatment (OR 3.1 (1.7 to 5.6), p<0.001). In a multivariate model, a dose of cyclopentolate remained associated with adverse reactions. Analysis per BMI and regime and age category and regime, indicated associations with low BMI (OR C+C 21.4 (6.7 to 67.96), p<0.001, respectively, C+T 5.2 (2.1 to 12.8), p<0.001) and young age (OR C+C 8.1 (2.7 to 24.8), p<0.001). CONCLUSIONS: Adverse reactions were common and almost exclusively involved the central nervous system. Both presence and severity were associated with repeated instillation of cyclopentolate 1%, low BMI and young age. In specific paediatric populations, a single dose of cyclopentolate must be considered. Vital function monitoring facilities are advisable. Adjustment of guidelines is recommended.

Implantation of phakic intraocular lens in 3 patients with oculocutaneous albinism.

UNLABELLED: We present 3 cases with oculocutaneous albinism in which a high refractive error was optically corrected by implantation of an Artisan iris-fixated phakic intraocular lens, with a follow-up of 8 to 14 years. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Comparison of wavefront-guided photorefractive keratectomy and foldable iris-fixated phakic intraocular lens implantation for low to moderate myopia.

PURPOSE: To compare and evaluate the visual and refractive outcomes of myopic wavefront-guided photorefractive keratectomy (PRK) and foldable phakic intraocular lens (pIOL) implantation for myopia. SETTING: Department of Ophthalmology, Haaglanden Medical Center, The Hague, The Netherlands. DESIGN: Comparative case series. METHODS: The differences in visual acuity and residual refractive outcomes after wavefront-guided PRK and Artiflex foldable pIOL implantation were compared in eyes with low to moderate myopia (spherical error -4.0 to -7.0 diopters [D]; maximum cylinder 2.25 D). One-year follow-up results are presented. RESULTS: At 1 year postoperatively, the mean decimal Snellen uncorrected distance visual acuity was 1.05 ± 0.21 (SD) in the PRK group (60 eyes) and 1.04 ± 0.21 in the pIOL group (33 eyes) and the mean corrected distance visual acuity (CDVA), 1.21 ± 0.18 and 1.24 ± 0.13, respectively. In the PRK group, 21.7% of eyes lost 1 to 3 lines of CDVA and 11.7% of eyes gained 1 or 2 lines. In the pIOL group, no eye lost lines of CDVA and 42% gained 1 or 2 lines. At 1 year, 80.0% of eyes in the PRK group and 90.9% of eyes in the pIOL group were within ± 0.50 D of the spherical equivalent. CONCLUSION: There were no statistically significant differences in safety and efficacy between the pIOL group and the PRK group at 1 year. However, the percentage of eyes that gained lines of CDVA was significantly higher in the pIOL group.

Visual evoked potentials during suppression in exotropic and esotropic strabismics: strabismic suppression objectified.

BACKGROUND: We performed an electrophysiological study in order to objectify suppression in strabismus. The extent of cortical involvement in the process of interocular suppression was also explored. Possible differences in the suppressive process of esotropic and exotropic strabismics were also studied. METHODS: An electroencephalographic recorder with eight leads was applied to the posterior one-third of the skull; three occipital, three parietal, and two temporal leads. We measured the activity of these visual cortical areas during stimulation of each eye under monocular as well as binocular viewing conditions with hemisinusoidal light pulses in a nature-like complex visual background. Recordings were made from six primary esotropic strabismic subjects and four primary exotropic and one consecutive exotropic strabismic subject. Also, five normal controls were studied. RESULTS: A characteristic, triphasic response complex was found at approximately 80 ms following the start of each light pulse under monocular viewing conditions in the dominant and the nondominant eye. However, under dichoptic viewing conditions in the nondominant eye of all esotropic cases as well as in the nondominant eye of three of five exotropic cases, this response complex was completely absent. They showed approximately 100% reduction of their cortical response activity. CONCLUSIONS: These results show the vast extent of the cortex that is involved in the suppressive process, giving a good insight in the power of suppression.