Refractive changes with post-rotatory nystagmus in healthy individuals

Purpose Post-rotatory nystagmus has been used to detect autism spectrum disorders in clinical settings. Although previous studies have focused on eye movements, they did not evaluate the change in ocular refraction during post-rotatory nystagmus. This study aimed to evaluate the changes in ocular refraction during post-rotatory nystagmus in healthy individuals. Methods A total of 34 healthy volunteers (mean age ± standard deviation, 20.9 ± 0.6 years) participated in this study. The ocular refraction during post-rotatory nystagmus was measured using MR-6000 (Tomey Inc.) on quick mode with a sampling rate of 30 Hz under noncycloplegic and cycloplegic conditions. The amplitude of post-rotatory nystagmus was calculated on the basis of the anterior eye images, while the ocular refraction measurements were simultaneously recorded. The accommodative convergence per accommodation ratio was calculated using the heterophoria method. Video oculography was performed to measure the angle of convergence during post-rotatory nystagmus. Results The changes in ocular refraction during post-rotatory nystagmus were significantly greater under the noncycloplegic condition than under the cycloplegic condition. The changes in ocular refraction during the post-rotatory nystagmus were significantly and positively correlated with the amplitude of post-rotatory nystagmus under the noncycloplegic condition. The angle of convergence during post-rotatory nystagmus was significantly higher under the noncycloplegic condition than under the cycloplegic condition. The changes in the angle of convergence were significantly and positively correlated with the predicted accommodative convergence. Conclusions These findings suggest that the accommodation was functional during the post-rotatory nystagmus to compensate for the retinal image slip, and the accommodative convergence can help weaken the nystagmus.

High Accommodative Convergence/Accommodation Ratio Consecutive Esotropia Following Surgery for Intermittent Exotropia: Clinical Feature, Diagnosis, and Treatment

Consecutive esotropia is a common and stereopsis-threatening consequence of surgery for intermittent exotropia. However, too little attention has been paid to the accommodative convergence per accommodation (AC/A) ratio in this condition. We aimed to describe the clinical features of patients who developed consecutive esotropia with a high AC/A following surgery for intermittent exotropia, compared to those with normal AC/A. In this retrospective cohort study, we identified 54 patients with consecutive esotropia who remained esotropic at one month after surgery. Patients were divided into two groups: normal AC/A and high AC/A groups. Clinical features and outcomes were compared between the two groups. Fourteen (25.9%) of the 54 were classified as high AC/A consecutive esotropia. Good preoperative control at near was the only significant preoperative factor associated with the development of high AC/A consecutive esotropia. Bifocal glasses were prescribed for all patients with high AC/A consecutive esotropia, and 11 (78.6%) of them achieved satisfactory alignment at distance and near fixations using bifocals. Patients with high AC/A consecutive esotropia had a significantly more successful alignment (0.9 vs. 13.0 prism diopters, p < 0.001) and better stereopsis (67.9 vs. 670.0 arc seconds, p = 0.04) than the normal AC/A counterparts at the final follow-up. We suggest that high AC/A consecutive esotropia could be successfully managed by wearing bifocals in most cases. A high AC/A ratio in patients with consecutive esotropia may be considered as a clinical marker heralding a better prognosis.

Unexpectedly high prevalence of asthenopia in Australian school children identified by the CISS survey tool

Background To date there have been few systematic attempts to establish the general prevalence of asthenopia in unselected populations of school-aged children. Thus, the aim of this study was to determine whether the incorporation of Borsting et al’s 2003 Revised Convergence-Insufficiency Symptom Survey (CISS) into a general school vision screening could aid in the identification of children with visual discomfort and indicate the need for further investigation. Methods Vision screening of an unselected middle school population investigated and analysed the incidence of self-reported nearwork-related visual discomfort via the CISS along with distance and near visual acuities plus non-cycloplegic autorefraction using a Shin-Nippon NVision-K 5001. Results Of the 384 unselected students approached in Grades 6–9, 353 participated (92.2%, mean 13.2 ± 1.4 years). The mean CISS score for the population without amblyopia and/or strabismus (96.0% of all students) was 16.8 ± 0.6, i.e., 45% of students in this cohort had CISS scores greater than one standard deviation above the mean found by Borsting et al. in 2003 during their validation study of the CISS on 9 to 18 year old children without binocular anomalies. Regression analyses indicated significantly higher (p < 0.001) mean CISS scores for the 3.2% who were hyperopes ≥ + 2.00D by non-cycloplegic autorefraction (27.7 ± 14.7) and for those who were amblyopic (24.3 ± 6.6) or strabismic (34.0 ± 9.8). The mean CISS score of 31.6 ± 9.0 for non-amblyopic/strabismic students having near vision poorer than 0.1 LogMAR was significantly higher (p < 0.001) than for those with good acuity. Conclusion The most important finding of this study was the high incidence of asthenopia in an unselected population and that refractive status per se was not a major contributor to CISS scores. The results highlight the usefulness of the CISS questionnaire for assessment of visual discomfort in school vision screenings and the need for future exploration of near binocular vision status as a potential driver of asthenopia in school students, especially given current trends for frequent daily use of computers and handheld devices and necessarily prolonged accommodative-convergence effort at near, both at school and at home.

Accommodative-Convergence Mechanism failure in HIV-Positive Non Presbyopic Patient on Highly Active Anti-Retroviral Therapy: A case report

Purpose: Accommodative-convergence mechanism failure could occur in non presbyopic HIV- sero positive patients on Highly Active Anti-Retroviral Therapy (HAART). This could be due to either direct neuronal infection by HIV, pathologic changes of the lens or the ciliary body or adverse effects of some individual drugs constituting the HAART regimen on the cranial nerves which play vital roles in the mechanism of accommodation and convergence. Case report: This is a case report of an accommodative- convergence mechanism failure in HIV positive non presbyopic 32-year-old male patient that was on HAART for more than five years. He presented with distance visual acuity (VA) of OD: 6/9 +2, OS: 6/9, and near visual acuity (NVA) of N24 both eyes, 3Δ esophoria at distance and 4Δ esophoria at near. Amplitude of accommodation (AA) was 3.50D and accommodative convergence/accommodation (AC/A) ratio was 6/1. Following comprehensive evaluation, his refractive correction was OD: Plano/-0.50DC X 180 6/5 and OS: Plano/-0.50DC X 90 6/5 at distance with near addition (Add) 2.50D N5. This was prescribed for regular wear in form of D-Top bifocal lens. Conclusion: These findings showed that HIV sero-positive adults on HAART could develop accommodativeconvergence mechanism failure, which may be characterized by low amplitude of accommodation, receded near point of convergence and high non presbyopic reading addition. These conditions may be under-recognized and need for reading addition of a non presbyopic age is often overlooked. Key Words: Accommodative-Convergence, HIV, Lateral Phoria, Refractive error.

Efficacy of vision therapy in impaired stereoscopic depth with intermittent exotropia (true divergence excess) with unilateral amblyopia: a case report

Divergence excess (DE) can be described clinically as exotropia at far greater than the near deviation by at least 10 prism dioptres (PD). We are reporting a rare case of 25-year-old female visited in the eye department for a routine eye check-up with a history of decreased vision in one eye. On examination, it was detected as a case of unilateral amblyopia with intermittent exotropia of true divergence excess with high accommodative-convergence over accommodation (AC/A) ratio. The patient was asymptomatic from exo-deviation due to the presence of binocular vision and good fusional reserve. The patient was started on active conventional vision therapy along with occlusion therapy. Post 16 weeks of constant therapy, a vision assessment with complete squint assessment along with binocular vision tests were performed. The result interprets to support the use of active conventional vision therapy as an integral part of the clinical treatment of amblyopia and intermittent exotropia. The rate of recovery of several monocular functions monitored during the vision therapy period provides the evidence of neural plasticity at multiple sites in the visual pathway in this adult amblyope. Therefore, if an ordered plan is being followed for the management of the patient of unilateral amblyopia and divergence excess, it can yield long-lasting improvement in visual acuity and binocular functions of any age.