综合视觉电生理检测对白内障术后视功能恢复的评估

目的 评价术前综合视觉电生理检测在判断白内障手术视功能预后中的作用。方法 白内障患者３１５例（４０８眼）术前常规检测图形翻转视觉诱发电位（ＰＶＥＰ）、红蓝光视网膜电图（ＦＥＲＧ）和视网膜电图的振荡电位（ＯＰｓ）。正常对照组１６２例（２６６眼）。术后检查眼底,术后３ｍｏ查矫正视力。结果 术后矫正视力≥０．５（Ⅰ组）和〈０．５（Ⅱ组）者与对照组相比,术前ＰＶＥＰ的Ｐ１００波振幅均下降、潜伏期均延长,后     

视觉诱发电位评价出生窒息婴儿视觉功能

目的采用闪光视觉诱发电位的检查方法评价出生窒息对患儿视觉功能的影响。方法出生3月龄和6月龄的婴儿共65例,行闪光视觉诱发电位（F—VEP）的检查。分为正常婴儿组和窒息婴儿组,对两组3月龄和6月龄的检查结果统计分析。结果3月龄窒息婴儿和正常婴儿比较,F-VEP的P2波潜伏时差异有统计学,P〈0．005。6月龄时,两组振幅差异有统计学意义,P〈0．005。NBNA评分恢复正常越迟,F-VEP的P2波的潜伏时越长,振幅越低。结论出生窒息婴儿的视觉传导存在明显异常,并且与窒息程度相关。     

The value of electrophysiology results in patients with epilepsy and vigabatrin associated visual field loss

PURPOSE: To determine the value of electrophysiological findings in patients with temporal lobe epilepsy and to relate these findings to the amount of concentric contraction of the visual field and the use of vigabatrin. METHODS: Electro-retinograms and electro-oculograms were done on 30 patients, operated for temporal lobe epilepsy. The patients were divided into three groups: (A) concentric contraction of the visual field associated with a history of vigabatrin medication (15 patients), (B) normal visual field with vigabatrin use (11 patients) and (C) normal visual field without vigabatrin medication (4 patients). RESULTS: Electrophysiological abnormalities were found in 50% of the patients in group A. The Arden ratio of the EOG was lowered in 57%. Abnormalities in the ERG were found: b-wave implicit time photopic F was prolonged (50%), b-wave amplitudes scotopic B (53%), C (73%) and G (50%) and photopic H (50%) were diminished. The amount of visual field loss and the total dose of vigabatrin used, showed only slight correlation with the ERG and EOG. The use of vigabatrin during the ERG and EOG recording in group A, gave a higher b-wave amplitude scotopic G in 64% of cases. The a-wave implicit times scotopic G (73%) and photopic G (59%) and H (73%) were shortened in group B. CONCLUSION: EOG was abnormal in 57% in group A. ERG abnormalities could only be found in 50% of group A, mainly in the inner retina. Since also the total dose of vigabatrin and the amount of visual field loss did not really show a correlation with the electrophysiological findings and results of literature are not unanimous, electrophysiology does not appear at present to be a good method to detect patients with, or at risk of, vigabatrin associated visual field loss. Regularly performed visual field examination remains the cornerstone in screening.     

Longitudinal quantitative assessment of vision function in children with cortical visual impairment.

PURPOSE: Cortical visual impairment (CVI) is bilateral visual impairment caused by damage to the posterior visual pathway, the visual cortex, or both. Current literature reports great variability in the prognosis of CVI. The purpose of this study was to evaluate change in vision function in children with CVI over time using a quantitative assessment method. METHODS: The visual acuity and contrast sensitivity of children with CVI were retrospectively assessed using the sweep visual evoked potential (VEP). Thirty-nine children participated in the visual acuity assessment and 34 of the 39 children participated in the contrast threshold assessment. At the time of the first VEP, the children ranged in age from 1 to 16 years (mean: 5.0 years). The time between measures ranged from 0.6 to 13.7 years (mean: 6.5 years). RESULTS: Forty-nine percent of the children studied showed significant improvement of visual acuity. The average improvement was 0.43 log unit (mean change: 20/205 to 20/76) in those who improved. The initial visual acuity was worse in those who improved compared with those who did not improve (p < 0.001). Forty-seven percent of the children studied showed significant improvement of contrast threshold. In those who improved, the average amount of improvement was 0.57 log unit (10 to 2.6% Michelson). The initial contrast threshold was significantly worse in those who improved compared with those who did not improve (p = 0.001). Also, the change in contrast threshold was related to age of the child (p = 0.017). CONCLUSIONS: Significant improvement in vision function can occur over time in children with CVI. In the present study, approximately 50% of the children improved and the remainder remained stable. No relation was found between etiology and improvement. Further investigation is warranted to better understand the prognosis for visual recovery in children with CVI.     

Visual electrophysiology in children with tumours affecting the visual pathway Case reports

In 9 children (8–14 years of age) with orbital, suprasellar or postchiasmal tumours, visual loss was studied by visual electrophysiology in relation to ophthalmologic and neuroimaging findings. Pattern electroretinography (PERG) and pattern visual evoked potentials (PVEP) to full and half-field pattern-reversal stimulation were recorded and PERG and PVEP changes were related to the tumour location. PERG wave P50 attenuation was found associated with the central retinal dysfunction in the child with orbital rhabdomyosarcoma; PVEP wave P100 delay was associated with the optic nerve dysfunction in a child with retrobulbar chondrosarcoma and in a child with optic nerve glioma; PVEP wave P100 asymmetry was associated with the crossed fibers dysfunction in a child with hypothalamic germinoma, and PVEP wave P100 uncrossed asymmetry was associated with postchiasmal dysfunction in children with postchiasmal tumours (one with pilocytic astrocytoma and two with angioma). On the other hand, normal PERG suggested that there was no central retinal dysfunction in a child with pleomorphic adenoma of the lacrimal gland, and normal PVEP to full and half-field stimulation excluded visual pathway dysfunction at the chiasm in a child with suprasellar arachnoidal cyst. Follow-up was useful in indicating whether visual dysfunction was progressive or not. We conclude that PERG and PVEP findings contributed to understanding whether the dysfunction originated was at the retina, in the optic nerve, chiasm or postchiasmal pathway.     

Phototherapeutic keratectomy in children: 5-year results

PURPOSE: To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) for the treatment of superficial corneal opacities, surface irregularities, epithelial instability, and reepithelialization failure in pediatric patients and study the visual and refractive changes after combined PTK and photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic. METHODS: This retrospective clinical study comprised children who had PTK or PTK combined with PRK from September 1996 to January 2000. The goals of treatment were to improve visual acuity and reduce or eliminate subjective ocular discomfort (eg, pain, lacrimation, and photophobia). A Nidek EC-5000 excimer laser was used in PTK mode with a 3.0 to 6.0 mm optical zone and a 4.0 to 7.5 mm transition zone. RESULTS: Forty-one pediatric patients (41 eyes) were included. Twenty-three eyes had PTK only, and 18 eyes had PTK combined with PRK to reduce preoperative myopia (11 eyes) or hyperopia (7 eyes). The mean patient age was 11.4 years (range 8 to 18 years) and the mean follow-up, 4.8 years (range 3 to 6 years). The best spectacle-corrected visual acuity (BSCVA) improved in all patients, and episodes of ocular pain or discomfort, lacrimation, and photophobia diminished. The mean preoperative BSCVA of 6/38 (range 6/10 to 1/60) improved to 6/12 (range 6/6 to 6/38) at the last postoperative examination. Eight eyes gained 5 or more Snellen lines of BSCVA; 11 gained 4 lines, 9 gained 3 lines, 7 gained 2 lines, 5 gained 1 line, and 1 eye was unchanged. No eye lost a line of BSCVA. The mean preoperative spherical equivalent (SE) decreased from -5.32 to -1.16 diopters (D) in the 11 myopic eyes and from +4.72 to +1.51 D in the 7 hyperopic eyes within 3 years of the combined procedure. CONCLUSIONS: Phototerapeutic keratectomy is an effective and safe procedure for the treatment of various surface corneal disorders in children. It can improve best corrected visual acuity and eliminate ocular pain and irritation. Preoperative myopia and hyperopia were effectively reduced by a combination of PTK and PRK.     

The key role of electrophysiology in the diagnosis of visually impaired children

PURPOSE: To describe the outcome of specialized electrophysiology in visually impaired children. METHODS: We carried out a retrospective evaluation of 340 electrophysiological examinations performed in 298 children over a 3-year period (2001-2003), with regard to demographic data, referral pattern, degree of compliance, and diagnostic results. Electrophysiology was performed without sedation or anaesthesia. In electroretinograms, DTL electrodes were used in combination with online selection of responses. Visual evoked potentials testing was performed with seven active occipital electrodes. RESULTS: The mean age of the children was 7 +/- 5 years; 72 (24%) of the children were mentally as well as visually impaired. Main reasons for referral were suspected posterior segment disease, abnormal visual development, unexplained low vision, high myopia, and suspected albinism. Compliance was good in 302/340 (88%), partial in 24/340 (7%), and absent in 14/340 (4%) of the examinations. Of the 326 successful procedures, 215 (66%) showed abnormal results. Tapetoretinal dystrophy (22%), opticopathy (16%), congenital stationary night blindness (13%), and cone dystrophy (11%) were the most frequently established diagnoses. Albinism was confirmed in 14 of 24 suspected patients; additionally, unsuspected misrouting was found in six. In 26 (9%) of the patients, a previously established diagnosis was changed. CONCLUSIONS: In a specialized setting, electrophysiological examinations can be performed successfully in visually impaired children. The results are essential for the final ophthalmological diagnosis and have important consequences for rehabilitation.     

Organic visual loss measured by kinetic perimetry and retinal electrophysiology in children with functional amblyopia

Purpose

To demonstrate an organic (retinal) amblyogenic defect in functional amblyopes not responding to treatment.

Methods

Twenty-four children (Mean age: 5.9?±?1.8 years; range: 4–10 years) with functional amblyopia were recruited for this study. All these children underwent complete ophthalmic and orthoptic evaluation. In addition, Kinetic Goldman Visual Fields (KGVF), Spectral Domain Optical Coherence Tomography (SD-OCT), full field flash electroretinograms (ffERG) and multifocal electroretinograms (mfERG) were also performed. Ratios were subsequently derived by comparing the amplitudes obtained from the amblyopic eye (AE) to the good eye (GE) for the a- and b-waves of the ffERG, as well as for the ring analysis of the mfERG.

Results

KGVF showed a central scotoma of varying size (3°–7°) and density (absolute to relative), with increasing target size in 14/24 patients whose best post-treatment vision in the AE ranged from 20/100 to 20/40. The scotoma decreased in size and density with improving vision until a plateau of recovery was reached. The remaining 10/24 patients with a vision?≥?20/30 showed no scotoma. SD-OCT showed no significant difference between the AE and GE. ffERG and mfERG were obtained in 18/24 patients. The ffERG AE/GE ratio was abnormal in 7 patients, 5 of which had large scotomas on KGVF. The mfERG ring 1 AE/GE ratio was significantly (p?<?.05) attenuated in 9/18 patients out of which 3 were no longer amblyopic. However, there was no significant difference (p?>?.05) in ring 1 AE/GE amplitude ratio between those who achieved 20/50–20/40 (.81?±?.26) and those with?≥?20/25(.86?±?.25).

Conclusions

The combined findings of central scotoma on KGVF and mfERG anomalies in patients who did not achieve optimal vision with treatment suggest an underlying organic defect impairing macular function.

     

The importance of electrode position in visual electrophysiology

Purpose

The DTL fibre electrode is commonly used to record the electric potentials elicited by stimulation of the retina. Two positions are commonly used: it is placed either on the cornea along the lower lid or in the conjunctival fornix. The PERG and OPs have previously been examined and compared under both conditions. The aim of this study was to examine the ERG, flicker response and on–off responses with differing electrode positions.

Methods

Before recruitment, all subjects underwent an ophthalmological examination. We enrolled 13 normal control subjects into the study aged 13–64 years, all with a visual acuity of ≥1.0. We recorded scotopic and photopic ERGs, flicker and on–off responses, for both electrode positions. On the first day, one eye had the electrode placed on the cornea along the lower lid and the other eye had it positioned in the conjunctival sac. On a second day, the recordings were repeated with the alternative electrode placements.

Results

ERG, on–off and flicker responses were all smaller by between 20 and 25% when the DTL electrode was positioned in the conjunctival sac, compared to when it was positioned on the cornea, as did the scatter in the data points. This indicates that there is no advantage clinically for one or the other placement.

Conclusions

Our results confirm other reports examining the effect of electrode position on electrophysiological potentials. When recording with the DTL electrode, it is important to ensure that it is placed at the same position in repeat recordings or in multicentre trials and that it is stable and does not move during recording.

     

Contrast sensitivity function in children: normalized notation for the assessment and diagnosis of diseases

The purpose of this article is to describe a normalized notation for the assessment of the contrast sensitivity in children. This notation is obtained dividing the log contrast sensitivity value found in a patient by the corresponding normative contrast sensitivity data. The ratio obtained describes the contrast sensitivity of a patient facilitating its understanding, assessment and consequently effective communications. This article shows the normalized notation developed for children aged from 3 to 7 years old. An evaluation of the contrast sensitivity in healthy and amblyopic patients has been shown in order to explain the procedure to follow. The use of normalized notation in clinical procedures will provide to the clinician a better understanding of the results and the changes over time as well by comparison in the assessment of an ocular disease.     

Causes of blindness, low vision, and questionnaire-assessed poor visual function in Singaporean Chinese adults: The Tanjong Pagar Survey

OBJECTIVE: To determine the prevalence rates and causes of low vision, blindness, and patient-assessed deficient visual function among Singaporean Chinese adults. DESIGN: Population-based cross-sectional survey. PARTICIPANTS: Singaporean Chinese adults 40 to 79 years old (n = 1152). METHODS: From an initial sampling frame of 40- to 79-year-old Chinese in the Tanjong Pagar district in Singapore, 2000 subjects were selected using a disproportionate, stratified, clustered, random-sampling method. Of 1717 eligible subjects, 1232 were examined (participation rate = 71.8%), and 80 adults who did not have visual acuity (VA) data were excluded from the analysis. MAIN OUTCOME MEASURES: Bilateral low vision was defined as best-corrected VA (BCVA) worse than 6/18 and 3/60 or better, and bilateral blindness as BCVA worse than 3/60 in the better eye or constriction of the visual field to within 10 degrees of fixation, in accordance with the World Health Organization criteria. Patient-assessed visual function was measured using a modified VF-14 questionnaire. RESULTS: The age- and gender-adjusted prevalence rates were 1.1% (95% confidence interval [CI], 0.6-1.8) for bilateral low vision and 0.5% (95% CI, 0.2-1.1) for bilateral blindness, and the mean visual function score was 98.6. The rates of bilateral low vision and blindness increased with age, whereas visual function scores decreased with age, even after adjusting for gender and education. Cataract accounted for 58.8% of bilateral low vision, 20.0% of bilateral blindness, and 52.0% of poor visual function (score<90). Glaucoma contributed to 60.0% of bilateral blindness. CONCLUSION: The age- and gender-adjusted rates of low vision and blindness were 1.1% and 0.5%, respectively. Glaucoma is a leading cause of blindness in Singaporean Chinese adults, in addition to well-recognized causes in the rest of Asia such as cataract.     

Ocular hypertension: results of a 10-year follow-up study

A multifactorial mathematical analysis with a diagnosis presented as a complex number was used in assessing results of 10-year follow-up of ophthalmic hypertension subjects. When the follow-up was over, the patients were divided into three groups by the findings at clinical examination. Group I patients (37%) recovered normal ophthalmic tone, group II patients (34%) remained hypertensive and group III (29%) developed an open angle primary glaucoma. The mathematical processing of diagnostic signs permitted an accurate diagnosis and monitoring of the process.