Resolution Perimetry Research Articles

Improved retinal and visual function following panmacular subthreshold diode micropulse laser for retinitis pigmentosa

ObjectivesTo examine the effect of subthreshold diode micropulse laser (SDM) on pattern electroretinography (PERG) and visual function in retinitis pigmentosa (RP).MethodsThe records of all patients (pts) undergoing SDM in a vitreoretinal subspecialty practice were reviewed. Inclusion criteria included the presence of RP evaluated before and after SDM by PERG. As a secondary outcome measure, the results of automated omnifield resolution perimetry (ORP) were also reviewed.ResultsAll eyes undergoing SDM for RP were eligible study, including 26 eyes of 15 pts; seven male and eight female, aged 16–69 (avg. 47) years. Retinal function by PERG improved by all indices, with significant improvements in the 24° field signal latency measures; the MagD(µV)/ Mag(µV) ratio (P < 0.0001) and the MagD(µV) amplitude (P = 0.0003). ORP significantly improved by all indices (p = 0.02–0.002). Average best-corrected chart visual acuities improved from 0.6 to 0.4 logMAR units (p = 0.02). There were no adverse treatment effects.ConclusionsSDM significantly improved chart visual acuity, mesopic logMAR visual acuity perimetry, and retinal function by PERG in RP without adverse treatment effects. Treatment responses indicate a significant capacity for rescue of dysfunctional retina. These results suggest that early and periodic treatment with SDM might slow disease progression and reduce long-term vision loss.

Bernhard Sabel and 'Residual Vision Activation Theory': a History Spanning Three Decades.

This review has the purpose of retracing the work of Professor Bernard Sabel and his group over the last 2-3 decades, in order to understand how they achieved formulation of the 'Residual Vision Activation Theory'. The methodology proposed is described, from the first studies in 1995 with High Resolution Perimetry requiring a six-months training period, to the new technologies, such as repetitive transorbital Alternating Current Stimulation, that require ten days of training. Vision restoration therapy has shown improvement in visual responses irrespective of age at the training, lesion aetiology and site of lesion. The hypothesis that visual training may induce network plasticity, improving neuronal networks in cortical and subcortical areas of both hemispheres, appears to be confirmed by recent studies including observation of the cerebral activity by fMRI and EEG. However, the results are quite variable and the mechanisms that influence cerebral activity are still unclear. The residual vision activation theory has been much criticized, both for its methodology and analysis of the results, but it gave a new impulse to the research in this area, stimulating more studies on induced cerebral plasticity.

The second face of blindness: Processing speed deficits in the intact visual field after pre- and post-chiasmatic lesions

PURPOSE Damage along the visual pathway results in a visual field defect (scotoma), which retinotopically corresponds to the damaged neural tissue. Other parts of the visual field, processed by the uninjured tissue, are considered to be intact. However, perceptual deficits have been observed in the visual field, but these functional impairments are poorly understood. We now studied temporal processing deficits in the intact visual field of patients with either pre- or post-chiasmatic lesions to better understand the functional consequences of partial blindness. METHODS Patients with pre- (n = 53) or post-chiasmatic lesions (n = 98) were tested with high resolution perimetry--a method used to map visual fields with supra-threshold light stimuli. Reaction time of detections in the intact visual field was then analyzed as an indicator of processing speed and correlated with features of the visual field defect. RESULTS Patients from both groups exhibited processing speed deficits in their presumably field as indicated by comparison to a normative sample. Further, in both groups processing speed was found to be a function of two factors. Firstly, a spatially restricted (retinotopic) influence of the scotoma was seen in longer reaction times when stimuli were presented in intact field sectors close to the defect. Secondly, patients with larger scotomata had on average longer reaction times in their intact field indicating a more general (non-retinotopic) influence of the scotoma. CONCLUSIONS Processing speed deficits in the visual field of patients with visual system damage demonstrate that visual system lesions have more widespread consequences on perception than previously thought. Because dysfunctions of the seeing field are expected to contribute to subjective vision, including visual tests of the presumed field may help to better understand vision loss and to improve methods of vision restoration and rehabilitation.

P 228. Repetitive transorbital alternating current stimulation (rtACS) alpha activity enhancement in patients with visual field deficits: a prospective, randomized, blinded, controlled, multicenter study

Retrospective studies suggested that rtACS simulates neuronal activity and results in neuroplasticity ( Fedorov et al., 2011 ). Prospective, randomized, controlled studies in patients with pre-chiasmatic optic nerve damage showed that rtACS reduces visual field deficits, enhances vision-related Quality of Life ( Gall et al., 2011 ) and entrains rhythmic brain activity (Schmidt et al., 2012). This is understood to reflect periodic enforcing ( Zaehle et al., 2010 ) associated with the activation of residual vision resulting in restoration of visual field deficits ( Sabel et al., 2011 ). The objective of the present prospective multicenter study is to provide evidence that alpha power gain over occipital electrodes is a bio-marker that can predict visual field size improvement. 80 patients with pre-chiasmatic partial optic nerve damage were randomized prior to inclusion in the sham-stimulation controlled rtACS trial ( RCT ). The stimulation group (n = 44) received rtACS for 20–40 min/day on 10 consecutive days. Treatment parameters were defined daily (1) by subject specific amperage when patients have an obvious perception of phosphenes, (2) the strongest alpha frequency over occipital electrodes (lower cut-off) and (3) the flicker-fusion frequency (upper cut-off). The control group ( n = 36) received subliminal stimulation. Electroencephalographic (EEG) power spectra were assessed on each of the 10 days over the occipital cortex. The size of visual fields was measured before and after treatment with high resolution perimetry (HRP). Data analysis was non-parametric regression to account for the heterogeneous patient-population. The EEG data shows a systematic enhancement of alpha-power after stimulation ( p < .05). This effect is stronger in the treatment group as compared with the placebo group ( p < .05). Enhanced alpha-power was associated with reduced visual field deficits ( p < <.05). Clinical results are reported in a complementary abstract. The results confirm that rtACS entrains alpha-oscillatory brain activity and show that changes in brain-rhythms is associated with changes in the visual field size. Thus, EEG alpha-oscillations seem to provide a bio-marker that can predict adaptive processes in a visual system with a pre-chiasmatic lesion. Future studies should continue to address the optimization of rtACS as well as the stratification by etiology prior to clinical application in individuals or small populations. The study was co-funded by the EBS Technologies GmbH.

IS 5. Clinical efficacy of non-invasive transorbital alternating current stimulation in optic neuropathy: A double-blind, randomized, sham-controlled multi-center study

Non-invasive brain current stimulation enhances neuronal plasticity in the visual system both in normal subjects and in patients with visual field loss ( Antal et al., 2012 , Sabel et al., 2011 ). In order to improve visual functions in patients with optic nerve damage we have now validated the efficacy of repetitive transorbital alternating current stimulation (rtACS) for the treatment of optic nerve damage in a randomized, multi-center clinical trial. A total of 98 patients were randomized in rtACS and sham group using stratified block randomisation considering the study center (3 levels) and the defect depth of visual fields at baseline (2 levels) as a potential prognostic factor. Patients were stimulated with 4 stimulation electrodes positioned near the closed eyes on 2 × 5 consecutive weekdays for 25–40 min daily with square pulse rtACS at 125% of individual phosphene threshold based on a preceding parameter optimization study (reported in an accompanying abstract). The sham group received a “minimal dose” of short-lasting single pulse phosphenes once per minute. Diagnostic sessions assessing visual field parameters, reaction times, visual acuity, and EEG were conducted 2 days before and after stimulation and at a 2-months follow-up. Eighty-two patients were finally included in the analyses. The primary analysis was directed to the comparison of percentage changes in detection rates in visual field diagnostics using the high resolution perimetry method (HRP) between the two treatment arms (rtACS vs. sham) with a significant difference in favor of rtACS ( p = 0.011; one-sided Mann–Whitney U ). RtACS-treated patients showed significant improvements after treatment (Hodges–Lehmann estimator for median increase 6.4%, 95%–CI (2.9%, 11.6%); p < 0.001 (Wilcoxon signed rank test one-sided). No significant change was seen in the sham-group (median change 1.1%, 95%–CI (−2.0%; 4.3%); p = 0.256. Due to a higher number of responders in the rtACS-group the mean improvement of visual fields was larger for visual field parameters after rtACS (23.96%) compared to sham (2.53%). RtACS-induced visual field changes were stable at a 2-months follow-up. Secondary perimetry measures confirmed this result, the most pronounced visual field changes being located in the central 5°. Covariance analysis for the logarithms of visual field change parameters did not reveal any significant differences between the study centers, neither as main factor nor as interaction with the treatment arm. EEG findings are reported in an accompanying abstract. RtACS treatment led to visual field improvement in patients with optic neuropathy suggesting that it is a viable clinical tool to improve visual fields in patients with long-lasting visual field loss. Together with the changes in EEG power spectra this finding supports the notion that visual system plasticity can be altered by non-invasive alternating current stimulation. The study was funded by EBS Technologies GmbH (Kleinmachnow, Germany) and the University of Magdeburg.

Evaluation of two treatment outcome prediction models for restoration of visual fields in patients with postchiasmatic visual pathway lesions

Visual functions of patients with visual field defects after acquired brain injury affecting the primary visual pathway can be improved by means of vision restoration training. Since the extent of the restored visual field varies between patients, the prediction of treatment outcome and its visualization may help patients to decide for or against participating in therapies aimed at vision restoration. For this purpose, two treatment outcome prediction models were established based on either self-organizing maps (SOMs) or categorical regression (CR) to predict visual field change after intervention by several features that were hypothesized to be associated with vision restoration. Prediction was calculated for visual field changes recorded with High Resolution Perimetry (HRP). Both models revealed a similar predictive quality with the CR model being slightly more beneficial. Predictive quality of the SOM model improved when using only a small number of features that exhibited a higher association with treatment outcome than the remaining features, i.e. neighborhood activity and homogeneity within the surrounding 5° visual field of a given position, together with its residual function and distance to the scotoma border. Although both models serve their purpose, these were not able to outperform a primitive prediction rule that attests the importance of areas of residual vision, i.e. regions with partial visual field function, for vision restoration.

The Second Face of Blindness: Processing Speed Deficits in the Intact Visual Field after Pre- and Post-Chiasmatic Lesions

PurposeDamage along the visual pathway results in a visual field defect (scotoma), which retinotopically corresponds to the damaged neural tissue. Other parts of the visual field, processed by the uninjured tissue, are considered to be intact. However, perceptual deficits have been observed in the “intact” visual field, but these functional impairments are poorly understood. We now studied temporal processing deficits in the intact visual field of patients with either pre- or post-chiasmatic lesions to better understand the functional consequences of partial blindness.MethodsPatients with pre- (n = 53) or post- chiasmatic lesions (n = 98) were tested with high resolution perimetry – a method used to map visual fields with supra-threshold light stimuli. Reaction time of detections in the intact visual field was then analyzed as an indicator of processing speed and correlated with features of the visual field defect.ResultsPatients from both groups exhibited processing speed deficits in their presumably “intact” field as indicated by comparison to a normative sample. Further, in both groups processing speed was found to be a function of two factors. Firstly, a spatially restricted (retinotopic) influence of the scotoma was seen in longer reaction times when stimuli were presented in intact field sectors close to the defect. Secondly, patients with larger scotomata had on average longer reaction times in their intact field indicating a more general (non-retinotopic) influence of the scotoma.ConclusionsProcessing speed deficits in the “intact” visual field of patients with visual system damage demonstrate that visual system lesions have more widespread consequences on perception than previously thought. Because dysfunctions of the seeing field are expected to contribute to subjective vision, including visual tests of the presumed “intact” field may help to better understand vision loss and to improve methods of vision restoration and rehabilitation.

Local topographic influences on vision restoration hot spots after brain damage

Vision restoration training (VRT) in hemianopia patients leads to visual field enlargements, but the mechanisms of this vision restoration are not known. To investigate the role of residual vision in recovery, we studied topographic features of visual field charts and determined residual functions in local regions and their immediate surround. We analyzed High Resolution Perimetry visual field charts of hemianopic stroke patients (n = 23) before and after 6 months of VRT and identified all local visual field regions with ("hot spots", n = 688) or without restoration ("cold spots", n = 3426). Topographic features of these spots at baseline where then related to (i) their respective local residual function, (ii) residual activity in their spatial neighbourhood, and (iii) their distance to the scotoma border estimated in cortical coordinates following magnification factor transformation. Visual field areas had a greater probability of becoming vision restoration hot spots if they had more residual activity in both local areas and in a spatially limited surround of 5° of visual angle. Hot spots were typically also located closer than 4 mm from the scotoma border in cortical coordinates. Thus, restoration depended on residual activity in both the local region and its immediate surround. Our findings confirm the special role of residual structures in visual field restoration which is likely mediated by partially surviving neuronal elements. Because the immediate but not distant surround influenced outcome of individual spots, we propose that lateral interactions, known to play a role in perceptual learning and receptive field plasticity, also play a major role in vision restoration.

Remaining Visual Field and Preserved Subjective Visual Functioning Prevent Mental Distress in Patients with Visual Field Defects

Background: Patients with visual field defects after visual pathway lesion may experience reduced vision-related quality of life (vrQoL). It has not been clarified how vrQoL impairments contribute to vision-related mental distress.Methods: One hundred and eight subjects with visual field defects caused by optic neuropathies (age M = 57.6; SD = 13.7 years) answered the National Eye Institute Visual-Functioning Questionnaire 39 (NEI-VFQ) for vrQoL and the SF-12 Short Form Health Survey for health-related quality of life. A 10 item composite of NEI-VFQ “visual functioning” and 5 items of “mental-health symptoms due to vision problems” were subjected to Rasch analysis. The test battery comprised static and High Resolution Perimetry (HRP). Regression and path analysis were used to investigate associations between QoL, mental distress, and perimetry results.Results: A higher level of “visual functioning” was associated with monocular impairment and a larger remaining visual field compared to binocular impairment. Subjective “visual functioning” but not visual field parameters predicted “mental-health symptoms due to vision problems” which was the only variable associated with the SF-12 mental component score. The SF-12 physical component score was less strongly associated with “mental-health symptoms due to vision problems.” Here, reaction time in HRP and mean threshold in perimetry were additional significant variables. Path analysis revealed a significant path from remaining visual field via visual functioning on mental health.Conclusion: Subjective consequences of visual impairments in everyday life impact mental health rather than “objective” visual function loss as measured by perimetry. Since a higher extent of vrQoL was related to lower levels of mental distress, the maintenance of vrQoL could reduce and prevent mental distress due to vision problems. Patients with persisting visual field defects may benefit from neuropsychological rehabilitation and supportive therapies.

Efficacy of vision restoration therapy after optic neuritis (VISION study): study protocol for a randomized controlled trial

BackgroundOptic neuritis is a frequent manifestation of multiple sclerosis. Visual deficits range from a minor impairment of visual functions through to complete loss of vision. Although many patients recover almost completely, roughly 35% of patients remain visually impaired for years, and therapeutic options for those patients hardly exist. Vision restoration therapy is a software-based visual training program that has been shown to improve visual deficits after pre- and postchiasmatic injury. The aim of this pilot study is to evaluate whether residual visual deficits after past or recent optic neuritis can be reduced by means of vision restoration therapy.Methods/designA randomized, controlled, patient- and observer-blinded clinical pilot study (VISION study) was designed to evaluate the efficacy of vision restoration therapy in optic neuritis patients. Eighty patients with a residual visual deficit after optic neuritis (visual acuity ≤0.7 and/or scotoma) will be stratified according to the time of optic neuritis onset (manifestation more than 12 months ago (40 patients, fixed deficit) versus manifestation 2 to 6 months ago (40 patients, recent optic neuritis)), and randomized into vision restoration therapy arm or saccadic training arm (control intervention). Patients will be instructed to complete a computer-based visual training for approximately 30 minutes each day for a period of 6 months. Patients and evaluators remain blinded to the treatment allocation throughout the study. All endpoints will be analyzed and P-values < 0.05 will be considered statistically significant. The primary outcome parameter will be the expansion of the visual field after 3 and 6 months of treatment as determined by static visual field perimetry and high resolution perimetry. Secondary outcome variables will include visual acuity at both low and high contrast, glare contrast sensitivity, visually evoked potentials, optical coherence tomography and other functional tests of the visual system, alertness, health-related quality of life, fatigue, and depression.DiscussionIf vision restoration therapy is shown to improve visual function after optic neuritis, this method might be a first therapeutic option for patients with incomplete recovery from optic neuritis.Trial registrationNCT01274702

Noninvasive transorbital alternating current stimulation improves subjective visual functioning and vision-related quality of life in optic neuropathy

Noninvasive repetitive transorbital alternating current stimulation (rtACS) can improve visual field size in patients with optic nerve damage, but it is not known if this is of subjective relevance. We now assessed patient reported outcomes to determine the association between visual field changes and vision-related quality of life (QoL). Patients having visual field impairments long after optic nerve damage (mean lesion age 5.5 years) were randomly assigned to a rtACS (n = 24) or sham stimulation group (n = 18). Visual fields and patient reported outcome measures (vision-related QoL: National Eye Institute Visual Function Questionnaire, NEI-VFQ and health-related QoL: Short Form Health Survey, SF-36) were collected before and after a 10-day treatment course with daily sessions of 20 to 40 minutes. The primary outcome measure was the percent change from baseline of detection ability (DA) in defective visual field sectors as defined by computer-based high resolution perimetry (HRP). Secondary outcome parameters included further HRP parameters as well as static and kinetic perimetry results. Changes in QoL measures were correlated with changes in primary and secondary outcome measures in both groups. DA increase in the defective visual field was significantly larger after rtACS (41.1 ± 78.9%, M ± SD) than after sham stimulation (13.6 ± 26.3%), P < 0.05. While there was a significant increase of DA in the whole tested HRP visual field after rtACS (26.8 ± 76.7%, P < 0.05), DA in sham-stimulation patients remained largely unchanged (2.7 ± 20.2%, ns). Results of secondary outcome measures (static and kinetic perimetry) provided further evidence of rtACS efficacy. Improvements in NEI-VFQ subscale "general vision" were observed in both groups but were larger in the rtACS group (11.3 ± 13.5, Z = -3.21, P < 0.001) than in the sham group (4.2 ± 9.4, Z = -1.73, P < 0.05) with a significant difference between groups (Z = -1.71, P < 0.05). DA change and some NEI-VFQ domains were correlated (r = 0.29, P < 0.05), but no significant correlations were observed between DA and SF-36 results. rtACS facilitates vision restoration after unilateral, long-term optic nerve lesion as assessed both by objective DA changes and improvements in some NEI-VFQ subscales. Both were positively but low correlated, which suggests that factors other than visual field size also contribute to improved vision-related QoL.

Outcomes of cataract surgery: a population-based developing world study in the Bhaktapur district, Nepal

To evaluate the visual outcome after cataract surgery in a population of Nepal. Population-based cross-sectional study. Forty years and above residing in Bhaktapur district. Subjects were selected from 30 clusters using cluster sampling procedure. All underwent a detailed examination at the base hospital, including logarithm of minimal angle of resolution visual acuity, refraction, applanation tonometry, cataract grading, retinal examination and perimetry when indicated. Visual acuity after cataract surgery. Out of 4003 subjects examined, 151 had undergone cataract surgery. Pseudophakia was present in 142 (94.0%), aphakia in nine (6%). Presenting and best-corrected visual acuity ≥6/18 was achieved in 123 (54.4%) and 164 (72.4%) eyes, respectively. Among the pseudophakic eyes, at presentation 122 (57.5%), 72 (33.9%), 18 (8.5%) and after best correction 162 (76.2%), 33 (15.8%), 17 (8.0%) had visual acuity of ≥6/18, <6/18-≥6/60 and <6/60, respectively. Retinal disease (35.5%), surgical complications (27.4%) and posterior capsular opacification (14.5%) were the principle causes of visual impairment after best correction in all eyes. There was no significant association in visual outcome based on age, sex, literacy and the duration of surgery. Correction of refractive errors, preoperative screening of coincidental diseases, reduction in surgical complication rates and monitoring of postoperative follow-up care has to be addressed seriously in order to improve the outcome of cataract surgery to meet standards proposed by the World Health Organization. In the future, longitudinal studies need to be undertaken to provide specific information on the outcomes of cataract surgery in this community.

The role of optical coherence tomography in the detection of pituitary adenoma

To analyse retinal nerve fibre layer (RNFL) thickness in eyes with compression of the optic chiasm by a pituitary adenoma. RNFL thickness was analysed with optical coherence tomography (OCT) and compared to visual field measurements using high-pass resolution perimetry (HRP). Sixteen eyes from eight patients with pituitary adenoma were studied. All had bitemporal visual field depression caused by compression of the optic chiasm. Patients were submitted to an ophthalmic examination more than 14 months after surgery (seven patients had undergone trans-sphenoidal and one trans-cranial adenomectomy). The examination included HRP, fundus photography and measurement of the peripapillar RNFL thickness using OCT. In spite of temporal visual field depression, not all eyes showed reduced RNFL thickness by OCT. This was also true for some eyes in which RNFL was judged to be reduced on fundus photographs. Contrary to our expectations, RNFL thickness in the nasal quadrant was normal in nine of the 16 eyes. Corresponding figures for the superior, inferior and temporal quadrants were eight, six and five, respectively. The overall RNFL thickness, as measured by OCT, did not correlate well with neural capacity, which is an index of remaining retino-cortical neural channels in HRP. RNFL thickness as measured with OCT was reduced in most, but not all, eyes with temporal field depression caused by chiasmal compression. The pattern of RNFL loss did not correlate well with the visual field defect. Sensitivity of RNFL thickness measurement in OCT was low. The method has limited value in the diagnosis of pituitary tumour compression.

The mechanisms of vision loss associated with a cotton wool spot

We characterized the perceptual, functional, and structural abnormalities associated with retinal ischemia during a cotton wool spot episode and its sequelae. The border of the visually salient field anomaly mirrored the quantitatively measured relative scotoma. Results of resolution perimetry and high resolution imaging indicated that there was a substantial loss of retinal ganglion cells within the affected region. A disruption in retinal nerve fiber arrangement was found at the cotton wool spot and within the arcuate relative scotoma. The presence of the arcuate relative scotoma is consistent with the hypothesis of failed signal transmission along the axons that pass through the cotton wool spot. The different levels of loss associated with the arcuate and focal scotomas indicate different underlying pathologies.

Long-term learning of visual functions in patients after brain damage

Purpose Systematic vision restoration training has been shown to improve the detection performance of brain-damaged patients with visual-field defects. So far, patients have been trained daily up to 6 months. We wished to determine whether intensive long-term training of 12 months further increases visual detection abilities. Methods Retrospective comparison of 17 patients with visual-field defects using vision restoration training for 12 months with a group of patients training for 6 months. Computer-based home training was completed for 6 months (about 195,000 stimuli presentations) or for 12 months (about 390,000 stimuli presentations). Visual fields were measured at baseline with Rodenstock Perimat 206 (monocular) at 90° eccentricity and at 54° eccentricity with high resolution perimetry (HRP) (binocular) after 6 months (post-6) and after 12 months (post-12) of training. Results Near-threshold perimetry revealed minor training effects, beyond 6 months, of 3.5% ( p = 0.099) in the right eye and of 1.5% ( p = 0.57) in the left eye. No effects of long-term training were evident in above threshold testing (0.8% detection improvement, n.s.). Conclusions Learning to detect above-threshold stimuli in patients with post-retinal lesions is completed after 6 months of practice with only marginal improvements thereafter. Near-threshold testing reveals that peripheral areas of the visual-field benefit from long-term training even if they are not trained.

Visual function in anterior ischemic optic neuropathy: Effect of Vision Restoration Therapy—A pilot study

To evaluate the effects of Vision Restoration Therapy (VRT) on the visual function of patients with anterior ischemic optic neuropathy. Randomized controlled double-blind pilot trial. 10 patients with stable anterior ischemic optic neuropathy (AION). All patients were evaluated before VRT and after 3 and 6 months of treatment by Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity, contrast sensitivity, reading speed, 24-2 SITA-standard Humphrey visual field (HVF), High Resolution Perimetry (HRP) (perimetry obtained during VRT), and vision-based quality of life questionnaire. Patients were randomized between two VRT strategies (5 in each group): I) VRT in which stimulation was performed in the seeing VF of the affected eye ("seeing field-VRT"); II) VRT in which stimulation was performed along the area of central fixation and in the ARV (areas of residual vision) of the affected eye ("ARV-VRT"). The results of the HRP, HVF, and clinical assessment of visual function were compared for each patient and between the two groups at each evaluation. Visual acuity qualitatively improved in the ARV-VRT group, however the change was not statistically significant (p=0.28). Binocular reading speed significantly improved in the ARV-VRT group (p=0.03). HVF foveal sensitivity increased mildly in both groups (p=0.059). HRP analysis showed a similar increase in stimulus accuracy in both groups (mean improvement of about 15%). All patients reported functional improvement after VRT. Despite a small sample, the study showed a trend toward improvement of visual function in the ARV-VRT group. Improvement of HRP in both groups may reflect diffusely increased visual attention (neuronal activation), or improvement of an underlying sub-clinical abnormality in the "seeing" visual field of patients with optic neuropathies.

How robust is the optic chiasm? Perimetric and neuro-imaging correlations

Analysis of form and function relationships with tumour-mediated dislocations and deformations of the optic chiasm. Results of magnetic resonance tomography and two forms of quantitative, computerized perimetry were contrasted in 31 patients with pituitary adenomata impinging on the chiasm, prior to treatment. Perimetric abnormalities ranged from none to modest. High-pass Resolution Perimetry (HRP) produced abnormal results in 10 cases and RareBit perimetry (RBP) in 15 cases. Overall, field defects and qualitative stages of deformation and dislocation of the chiasm were well correlated. Among quantitative indices, the best correlations were obtained by a measure of the cranio-caudal position of the chiasm. On average, an elevation of the chiasm by 6 mm will be associated with abnormal visual fields in 50% of the cases. An additional elevation of 5 mm will raise the incidence of field defects to 90%.

Resolution visual fields in children surgically treated for congenital cataract

Abstract Purpose: To evaluate best‐corrected visual acuity (BCVA) and high‐pass resolution perimetry (HRP) visual fields in children surgically treated for congenital cataract. Methods: BCVA and HRP was recorded from 10 aphakic children, aged 10‐15 years and surgically treated for bilateral dense cataract before the age of nine months, and from six aphakic children, aged 10‐15 years and surgically treated for bilateral partial cataract at ages between 6 months and 9 years. Twenty‐three healthy children, 11 years of age, served as controls. Results: The aphakic children had significantly (p &lt; 0.0001) lower BCVA in their best eye (range 0.1‐1.3) compared to controls (range 1.0‐1.6). Two aphakic children were visually disabled according to WHO. The children with previous dense bilateral cataract showed significantly (p &lt; 0.05) lower sensitivity in their resolution visual fields (from their best eyes) compared to both controls and children with previous partial cataract. The dense cataract group also showed significantly (p&lt;0.05) smaller difference between the innermost (5 deg) and the outermost (20‐30 deg) eccentricity locations in their visual fields than the other two groups. Conclusions: Dense cataract, even when surgically treated before the age of nine months, causes persistent impairment of spatial vision both in the fovea and the visual field. Partial cataract appears only to reduce visual acuity.

Influence of ageing on visual field defects due to stable lesions

Background:Knowledge about the effects of ageing on visual field defects is very sparse.Methods:Long-term follow-up records were examined from 28 patients with light-to-moderate visual field defects remaining after surgery for pituitary...

Intraocular pressure before and after visual field examination

To evaluate the influence of visual field (VF) examinations using modern techniques with short examination times on the intraocular pressure (IOP). Sixty-one consecutive patients, aged 28-90 years, 40 women and 21 men, were examined. Forty patients were treated for glaucoma and 21 were untreated patients with ocular hypertension or suspected glaucoma. Twenty-one subjects were examined using the Humphrey Field Analyzer, using SITA programs, and 40 with high-pass resolution perimetry (HRP). Goldmann applanation tonometry was performed immediately before and after the VF examinations. A difference in IOP of more than 2 mm Hg before and after the VF examination was observed in 14 of the 61 patients (23%). The maximum change in each direction was 4 mm Hg. The mean differences were not significant. All eight subjects with increasing IOP after VF examinations were examined using the HRP technique (P=0.04). Modern VF techniques with short examination time do not seem to significantly influence IOP.