调节与辐辏因素导致视疲劳的诊断和治疗

视疲劳的临床表现复杂,因其症状的非特异性给临床诊断和病因治疗带来一定的困难.随着对该病的认识深入,发现其病因甚为复杂,并且往往是多因素混合导致发病.如果只是单纯的对症治疗效果并不理想,探寻病因进行对因治疗才是根本的治疗策略.目前已经明确多种因素可导致视疲劳,通过必要的眼科及视光学检查可确保明确且全面的病因诊断.目前针对视疲劳的病因治疗难易不同.一些病因只要去除和矫正就能避免视疲劳,而另一些就显得相对困难,调节和辐辏因素导致的视疲劳即属于后者.另一方面由于调节和辐辏检查的专科性,使得它们在视疲劳中的诊断和治疗具有一定的难度和特殊性.我们对目前调节和辐辏在视疲劳中的诊断和治疗现状进行总结,以期为临床诊治带来帮助.     

Posttraumatic convergence insufficiency

Convergence insufficiency was encountered following closed head trauma in 23 patients. The most common complaints included difficulty reading and diplopia at near. The severity of the head trauma varied. There was no correlation between the severity of the head trauma and the severity of the convergence insufficiency. A normal near point of convergence was encountered in six of the 23 patients; all six patients had abnormal convergence reserves when measured with prisms. Treatment consisted primarily of convergence exercises and prisms. Bilateral medial rectus resections were required in two patients. Response to therapy was variable and often incomplete. The anatomic localization of convergence insufficiency secondary to head trauma remains unknown, although lesions in the occipital lobe and upper midbrain both seem capable of producing this syndrome.     

Methyldopa-related convergence insufficiency

A case report of convergence insufficiency related to the use of methyldopa is presented. Methyldopa is a systemic antihypertensive agent. It has sympatholytic properties which lower blood pressure by decreasing peripheral vascular resistance. The proposed effects of methyldopa on binocular vision are reduced accommodative convergence and increased demand on fusional convergence. These effects would create a susceptibility to convergence insufficiency. To my knowledge, an association between methyldopa and convergence insufficiency has not been previously reported.     

Orthoptic treatment of accommodative strabismus

Orthoptic treatment of accommodative strabismus is difficult because of variability of deviation and neutralisation. In first, the treatment of synoptophoria is practised more easily. It is often completed by optic treatment and medical treatment.     

Classification criterion for success in the treatment of convergence insufficiency

Using data collected from a retrospective study of the records of 110 patients diagnosed as having convergence insufficiency, a model has been developed which allows the classification of a patient into one of two categories of success (total or partial/none) on the basis of an initial examination. The subjects were treated with orthoptics and classified into either the total success group (no objective or subjective visual difficulties) or the partial/no success group. Stepwise discriminant analysis was used in the data reduction phase in which 6 of 14 possible variables were selected which best explained the variation in the degree of success. These six variables were: (1) the AC/A ratio; (2) the negative vergence blur value at 40 cm; (3) the recovery value of the positive vergences at 6 m; (4) the break value of the positive vergence at 6 m; (5) the amplitude of accommodation; and (6) the frequency of the deviation. Subjects were more likely to be successful when 1, 2 and 3 were high, 4 and 5 were low, and the deviation was latent. Discriminant analysis using these six variables allowed 25 of 33 (76%) of the patients to be correctly classified in terms of their success. The application of the model for classifying patients with convergence insufficiency is presented and briefly discussed.     

A survey of treatment modalities for convergence insufficiency.

BACKGROUND: Convergence insufficiency (CI) is a common and distinct binocular vision disorder. However, there is a lack of consensus regarding the treatment most appropriate for Cl. Possible treatment modalities include base-in prism, pencil pushup therapy (PPT), reading glasses, home-based vision therapy/orthoptics (HBVT), and office-based vision therapy/orthoptics (OBVT). The purpose of this study was to investigate the care process for Cl by surveying eyecare professionals regarding the most common treatment modalities used by both optometrists and ophthalmologists across the United States. METHODS: Surveys requesting doctors to indicate which treatment(s) they prescribed and believed to be most effective for symptomatic CI patients were mailed to 863 optometrists and 863 ophthalmologists in the United States. RESULTS: Fifty-eight percent of the optometrists responded to the survey; the most common treatment prescribed was PPT (36%) followed by HBVT (22%) and OBVT (16%). For the ophthalmologists (who had a 23% response rate), the most common treatment prescribed was PPT (50%) followed by HBVT (21 %) and base-in prism (10%). CONCLUSIONS: This survey suggests that most eyecare practitioners prescribe PPT as the initial treatment for CI.     

Efficacy of treatment for convergence insufficiency using vision therapy

PURPOSE: The purpose of this study was to determine if vision therapy (VT), as practised within the constraints of UK optometric practice, employing graded routine eye exercises, is as an effective method for treatment of convergence insufficiency (CI) as previously published data suggest. The study also evaluates the associated symptoms before and after therapy. METHODS: As many optometrists diagnose CI solely on the basis of near point of convergence (NPC) and treat only when symptoms are present (Letourneau et al., 1979; Rouse et al., 1997), in this study CI was defined as NPC of 10 cm or greater (either with or without the presence of asthenopic symptoms for near work) accompanied by exophoria greater at near than at distance. The effect of treatment by optometric vision therapy (OVT) on the NPC and number of symptoms was investigated for 92 patients by retrospectively reviewing the clinical records. Success was defined as the restoration of NPC to normal values and significant reduction in the presenting symptoms. RESULTS: The effect of treatment on the NPC was shown to be highly significant (t = 14.61, p < 0.001). Although treatment times were slightly longer, the success rates were higher than reported by other authors. Post-treatment values for NPC were: <10 cm (98.9%), <8.5 cm (95.7%) and <6.5 cm (80.4%). Longer treatment times were noted for patients who complained that the text appeared to move (chi2, p = 0.007). CONCLUSION: Vision therapy is an effective method for treatment of CI.     

Orthoptic treatment of dyslexia]

It is assumed that dyslexia is due to a brain-organic syndrome, either congenital or acquired in infancy, with specific gnostic deficiencies and faulty controlled binocular vision. The latter is expressed by an intermittent alternating central scotoma which is thought to be responsible for impaired visual perception during reading. The aim of the orthoptic treatment of dyslexia must therefore be to eliminate the alternating central scotoma by stabilizing the binocular vision, and thus to improve reading ability by achieving unimpaired visual perception.     

Characteristics of convergence insufficiency

Convergence insufficiency (CI) is a well-known syndrome of binocular visual dysfunction. In a review of 58 papers, considerable variation was noted in the criteria used to define the condition. Symptoms and decreased positive fusional vergences (both at the nearpoint) were the only criteria named in more than one-half of the studies. An extended nearpoint of convergence (NPC) and increased exophoria at near were criteria in about one-third of the papers. Examination of data in the reviewed papers shows that although considerable variability was noted, the distance exodeviation, distance negative vergences, visual acuity, refraction, and stereopsis were about the same as population norms. Positive vergences, negative vergence at near, and NPC were somewhat less than population norms. Vergences relative to Sheard's criterion, the near exophoria, accommodative amplitude, and the AC/A ratio were consistently below those derived from population norms. This considerable variation may largely be a result of different criteria used for diagnosis, subpopulations within the data, and other confounding factors.     

Associated convergence and accommodative insufficiency

Nine patients were described with a syndrome consisting of accommodative and convergence insufficiency. All but two had received extensive orthoptic therapy without benefit in the past. Near points of convergence and accommodation, fusional amplitudes and the AC/A ratio were determined and the data compared with those from a group with ordinary convergence insufficiency. The results show that this syndrome is a distinct and separate entity from ordinary convergence insufficiency. Special therapeutic measures include base in prisms and bifocal correction.From the Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland.This study was supported by Research Grant EY-00274 from the National Eye Institute, Bethesda, Maryland.