Binocular vision & strabismus quarterly最新文献

Purpose: To evaluate the MRI cross sectional greater area of the unilateral superior oblique (SO) muscle in patients with congenital or acquired superior oblique palsy to detect asymmetries and to determine if there is any relationship between the degree of vertical deviation and the muscle size determined by imaging.

Methods: Magnetic Resonance Imaging coronal images were obtained in primary position, supraversion and infraversion. Interocular differences and intergroup differences were compared in 17 patients with unilateral acquired or congenital SO palsy and 15 orthotropic control subjects.

Results: Mean maximal difference was 3.56 +/-0.83 mm(2) (p 0.01) between healthy and paretic eye in the paretic group, and 1.08 +/-0.40 mm(2) (p 0.02) in the control group. Statistical Intergroup comparison was p 0.02 (conventionally statistically significant). In 9 patients the maximal interocular difference was detected in 44.4% in infraversion, 33.3% indistinctly in supra- and infraversion and 22.2% in primary position. The correlation coefficient between vertical deviation and interocular asymmetry was not conventionally statistically significant at p>0.05.

Conclusions: Patients with unilateral superior oblique palsy showed significant MRI asymmetry, which was represented by a relatively greater healthy SO muscle size, in the paretic congenital group. We found no association between the SO muscle size and the degree of any vertical deviation present.

Purpose: To investigate the prevalence of specific reading disability in children with functional amblyopia and to explore the relationship between the two.

Methods: In this prospective study, 20 consecutive children, aged 6 to 15 years (mean 8 +/-1.99 years), and diagnosed with amblyopia underwent a vision and reading assessment. The orthoptic examination included the assessment of participants' visual acuity, ocular motility and binocular functions. Specific reading disability was diagnosed using the Wide Range Achievement Test (WRAT III Reading Subtest). Intelligence, phonological awareness, rapid automatized naming (RAN), and the ability to read pseudo or nonsense words was also assessed using various psycho-linguistic reading tests.

Results: The prevalence of specific reading disability in this small series of amblyopic children was found to be 5% (n=1/20). This was even less than that reported in the local Victoria general population (16%). The type of amblyopia appeared related to phonological awareness (p=0.018) and decoding words (p=0.024), those with anisometropic amblyopia performing significantly better on these tasks than the strabismic amblyopes. The presence of binocular vision functions was also related to decoding words; those with binocular single vision performed better than those with suppression and lacking single binocular vision (p=0.007). Generally, amblyopic children also showed a lower RAN score when compared to phonological awareness score. There was no statistically significant difference for the severity of amblyopia (p=>0.05).

Conclusions: In this very small pilot series, reading disorders were relatively rare in children with amblyopia. However, strabismic amblyopia and presence of suppression may have an adverse effect on phonological skills. In addition, amblyopia may be associated with a deficit in RAN. Further research is needed and planned to gain a better understanding about the relationship between amblyopia and reading ability.

Introduction: These two eye movements have not been previously studied in this condition by this method.

Methods: Five cases were studied. Both visual acuity and eye examination of anterior and posterior segments were normal. A Nicolet Nystar Plus system with chloride silver electrodes was used to record the EOG.

Results: Of the two systems under study, the smooth pursuit system showed the most relevant anomalies, both in the Duane's eye and in the apparently healthy eye. No correlation was found between the pursuit and optokinetic nystagmus disorders. In some cases, more significant abnormalities were observed in the clinically normal eye.

Conclusions: The results clearly demonstrated a significant impairment of the pursuit system. This suggests that this motor disorder is not exclusively caused by hypoplasia or aplasia of the nucleus of the abducens nerve (VIth cranial nerve). These abnormalities might be related to a poor development of the rhombencephalon since both supramotor nuclei as well as the pathways of this system arise from this region of the embryonic brain. In the particular case of OKN, the supramotor nuclei have a different origin. Therefore, these systems might be affected differently.

Pronounced visual loss can lead to nystagmus, provoking oscillopsia and distressing ocular sensations. The treatment of acquired nystagmus remains difficult and various therapeutic options are attempted with limited results. We report the case of a man with acquired nystagmus and excessive ocular discomfort, successfully treated with repeated retrobulbar injections with botulinum toxin.

Purpose: The HR (prism diopters [PD] per mm of corneal light reflection test [CLRT] asymmetry for strabometry) varies in humans from 14 to 24 PD/mm, but is totally unpredictable. Photo(grammetric) HR calibration in (of) each case facilitates acceptable strabometry precision and accuracy.

Method: Take 3 flash photos of the patient with both the preferred eye and then the deviating eye fixating straight ahead and then again with the deviation eye fixing at (+/-5-10 PD) the strabismic angle on a metric rule (stick) one meter away from the camera lens (where 1 cm = 1 PD).

Results: On these 3 photos, make four precise measurements of the position of the CLR with reference to the limbus: In the deviating eye fixing straight ahead and fixating at the angle of deviation. Divide the mm difference in location into the change in the angle of fixation to determine the HR for this patient at this angle. Then determine the CLR position in both the deviating eye and the fixing eye in the straight ahead primary position picture. Apply the calculated calibrated HR to the asymmetry of the CLRs in primary position to determine the true strabismic deviation.

Conclusions: This imaging method insures accurate Hirschberg CLRT strabometry in each case, determining the deviation in "free space", under conditions of normal binocular viewing, uncontaminated by the artifacts or inaccuracies of other conventional strabometric methods or devices. So performed, the Hirschberg CLRT is the gold standard of strabometry.

Introduction: State-wide cooperative programs for pediatric vision screening utilizing the MTI photoscreener and centralized interpretation were established in Alaska (The Alaska Blind Child Discovery, ABCD) and in Tennessee (Tennessee Lions Outreach).

Methods: Details of setup, implementation and interpretation of the state-wide MTI photoscreening programs are compared through 2002. The absolute numbers of children screened and the breakdown in interpretation categories are presented.

Results: ABCD screened 14,000 children while Tennessee Lions screened 100,800. Similarities between ABCD and Tennessee programs were funded by Lions Clubs and other charitable and public health organizations, community screening and each had coordinated centralized image interpretation and notification. The programs differed by clinic focus (Tennessee Lions organized pre-schools while ABCD used village and community health fairs and schools), parent notification (Tennessee Lions communicated through pre- schools and ABCD mailed directly to parents), and image interpretation (Tennessee used VOIC age-based and pupil-size crescents while ABCD used "delta-center crescent"). Predictive value positive was 73% for Tennessee and 89% for ABCD. Tennessee achieved better followup on referrals after a specific coordinator was employed. Image interpretation breakdown for ABCD: Tennessee Lions Outreach were anisometropia (29%:34%), high hyperopia (33%:16%), astigmatism (18%:30%), strabismus (7%:15%), myopia (5%:2%), cataract (0.7%:0.2%). Two state-wide programs detected 3216 amblyopic children at a charity borne-cost of 1.5 million dollars. If the parents persisted with appropriate amblyopia therapy, the expected societal value was estimated at 17 million dollars. Lacking societal mandate and funding, these concerted charitable efforts only achieved a community penetration rate of 10% to 14%.

Conclusion: National adoption of preschool vision screening by a method with similar or even better validity and cost effectiveness as MTI photoscreening, ideally in the pediatric medical home, is warranted.