Ocular deviation after unilateral laser in situ keratomileusis.
(9/204)
Laser keratomileusis and excimer laser photorefractive keratectomy in situ are widely used therapies for treating myopia. The corrections of refractive error by glasses or contact lens result in a relatively equal refractive correction on both eyes. However, refractive surgery on a single eye can cause a focus disparity between both eyes and may result in the impairment of fusion leading to strabismus. This article aims to report a case where diplopia and esotropia occurred 1 month after laser keratomileusis (LASIK) in situ for the correction of myopia. (+info)
Spatial localization in esotropia: does extraretinal eye position information change?
(10/204)
PURPOSE: To investigate the accuracy of spatial localization in children with a specific type of convergent strabismus, fully accommodative esotropia. METHODS: Two groups of children, with right and left fully accommodative esotropia, respectively, pointed at targets located centrally and eccentrically on a computer touchscreen without being able to see their hands. The size and the direction of the horizontal pointing responses were recorded under two conditions: when their eyes were aligned (wearing spectacles) and when they were squinting (not wearing spectacles). A group of children without strabismus but with hypermetropia were assessed as controls. RESULTS: For both fully accommodative groups, the pointing responses to the central target shifted in the direction of the nonsquinting eye when deviations were manifest. No difference was found for the eccentric targets. No difference was found for the hypermetropia group with any target. CONCLUSIONS: These results are consistent with an alteration in the extraretinal eye position information (efference copy, extraocular muscle proprioception, or both) that is used in spatial localization. (+info)
Unusual presentations of accommodative esotropia.
(11/204)
PURPOSE: Most patients with accommodative esotropia are first examined between the ages of 6 months and 2 years. This paper discusses unusual presentations of accommodative esotropia that occur outside of this age-group and/or have a precipitating event that triggered the esotropia. In a series of patients who were from 5 to 11 years of age, trauma was the precipitating event. In some of the patients under 6 months of age, high myopia, as well as a moderate to large amount of hyperopia, was the cause. In 1 teenager, diabetic ketoacidosis precipitated accommodative esotropia. METHODS: We reviewed all of our records for the past 25 years involving patients with a diagnosis of esotropia, and we found 17 patients who had unusual presentations of accommodative esotropia. Of 8 who were under the age of 6 months, 2 had high myopia and 6 had moderate to large amounts of hyperopia. Nine patients were older than age 5. Eight of the 9 had suffered trauma associated with the presentation of accommodative esotropia, and 1 patient's accommodative esotropia was associated with diabetes. The patients with myopia received their full myopic correction. The children under 6 months of age with hyperopia received their full cycloplegic refraction, and the children over age 5 received the most plus that they were able to accept in a noncycloplegic state consistent with good visual acuity (at least 20/30 in each eye). RESULTS: In 17 patients, accommodative esotropia was initially controlled with glasses. In a few of the trauma cases, bifocals were required for control of near deviation. Only 2 of the patients, in whom onset was under 6 months of age, came to surgery. One had hyperopia controlled for 2 years with glasses, and the other had myopia controlled for 3 years with glasses. CONCLUSIONS: Accommodative esotropia can occur prior to 6 months of age. It can also occur in older children (5 to 14 years of age) and can be precipitated by trauma or diabetic ketoacidosis. (+info)
The role of anisometropia in the development of accommodative esotropia.
(12/204)
PURPOSE: To determine if anisometropia increases the risk for the development of accommodative esotropia in hypermetropia. METHODS: Records of all new patients with a refractive error of > or = +2.00 (mean spherical equivalent [SE] of both eyes) over a 42-month period were reviewed. Three hundred forty-five (345) patients were thus analyzed to determine the effect of anisometropia (> or = 1 diopter [D]) on the relative risk of developing esodeviation and of requiring surgical correction once esodeviation was present (uncontrolled deviation). RESULTS: Anisometropia (> or = 1 D) increased the relative risk of developing accommodative esodeviation to 1.68 (P < .05). Anisometropia (> or = 1 D) increased the relative risk for esodeviation to 7.8 (P < .05) in patients with a mean SE of < 3 D and to 1.49 (P < .05) in patients with SE of > or = 3 D. This difference was significant (P = .016). In patients with esotropia and anisometropia (> or = 1 D), the relative risk for an uncontrolled deviation was 1.72 (P < .05) compared with nonanisometropic esotropic patients. Uncontrolled esodeviation was present in 33% of anisometropic patients versus 0% of nonanisometropic patients with a mean hypermetropic SE of < 3 D (P = .003); however, anisometropia did not increase the relative risk of uncontrolled esotropia in patients with SE of > or = 3 D. Although amblyopia and anisometropia were closely associated, anisometropia increased the relative risk of esodeviation to 2.14 (P < .05) even in the absence of amblyopia. CONCLUSIONS: Anisometropia (> 1 D) is a significant risk factor for the development of accommodative esodeviation, especially in patients with lower overall hypermetropia (< 3 D). Anisometropia also increases the risk that an accommodative esodeviation will not be fully eliminated with hypermetropic correction. (+info)
Conditions of perceptual selection and suppression during interocular rivalry in strabismic and normal cats.
(13/204)
Presenting the two eyes with incongruent stimuli leads to the phenomenon of interocular rivalry. At any given time, one of the stimuli is perceptually suppressed in order to avoid double vision. In squinting subjects, rivalry occurs permanently also for congruent stimuli because of developmental rearrangement of cortical circuitry. In this study, we have investigated the dynamics and stimulus dependence of rivalry in six esotropic, four exotropic and three non-strabismic cats. As an indicator for perception, we used optokinetic nystagmus that was induced by moving gratings. The esotropic cats were tested for their visual acuity by means of a jumping stand procedure. The results show that one eye can dominate perception even if both eyes have equal visual acuity and are presented with stimuli of equal contrast. Strong eye dominance asymmetry was found in all but one of the tested cats. Notably, all three of the normal cats showed a clear asymmetry in perceptual selection. Measurements with varying contrast and velocity of the stimuli revealed that the influence of these parameters on perceptual selection was independent of the presence of strabismus. In all cats, the time during which a given eye dominated perception increased with the contrast and decreases with the velocity of the stimulus presented to this eye. (+info)
Long-term outcome and predictor variables in the treatment of acquired esotropia with botulinum toxin.
(14/204)
PURPOSE: To determine the long-term results of botulinum therapy in acquired esotropia and to identify predictors of a satisfactory outcome. METHODS: Sixty-eight children (age range, 8-64 months) with acquired esotropia were enrolled in a prospective study. Botulinum toxin A was injected in the two medial recti. Motor and sensory statuses were evaluated at 1 and 2 weeks; 3, 6, and 12 months; and every year after the last injection. Univariate and multivariate logistic regression analyses were performed to relate motor and sensory outcome to variables recorded as potential predictors. RESULTS: After an average follow-up of 4.8 years since the last injection, motor success was obtained in 36 children with one injection (52.9%), increasing to 48 (70.6%) and 60 (88.2%) children after two and three injections, respectively. Forty-eight (70.6%) patients had at least peripheral fusion (category 1 binocularity) and 32 (47.1%) had stereoacuity of at least 400 seconds of arc (category 2 binocularity). Higher hypermetropia, less severe amblyopia, and a smaller angle of esotropia were the best predictors of motor success. Minimal amblyopia and favorable motor alignment were associated with better binocularity outcome. CONCLUSIONS: Botulinum is an effective long-term treatment of acquired esotropia. It is especially useful in children with high hypermetropia, minimal amblyopia, and small esotropic deviation. (+info)
Altered expression of alternatively spliced isoforms of the mRNA NMDAR1 receptor in the visual cortex of strabismic cats.
(15/204)
PURPOSE: Although much has been written about the role of the NMDA receptor's role in experience dependent visual plasticity, the function of the NMDAR1 receptor subunit in the post-plasticity stage of development is still not well understood. However, in the well studied model of strabismic amblyopia where binocularity is reduced, but where most primary visual cortex neurons can be driven by one or other eye, the density of expression of NMDAR1 receptor protein is significantly reduced, compared to normals. This study aims to identify which of eight isoforms of the spliced heterogeneous variants of the NMDAR1 mRNA receptor gene are associated with this decrease in expression as a means of elucidating possible function. METHODS: A series of digoxygenin-labelled oligonucleotide probes based on the human gene sequence have been used for in situ hybridization (ISH) of sections from the striate cortex of four adult cats. The probes were used to uniquely detect the expression of alternatively spliced mRNA variants in 66,487 cells from sections from the area centralis projection of two normal cats and two cats made esotropic as kittens by tenotomy at two weeks of age. RESULTS: As expected, total NMDAR1 mRNA isoform expression was significantly lower in the striate cortex of strabismic compared to normal cats. The proportion of cortical cells expressing the R1-a, R1-b, and R1-1 isoforms in strabismic animals was decreased while the proportion expressing R1-3 was increased, especially in layers V and VI. No significant difference in expression of the R1-2 and R1-4 isoforms was seen comparing strabismic and normal cats. CONCLUSIONS: These results confirm our previous findings and suggest that transcriptional inhibition of specific isoforms of NMDAR1 mRNA may underlie the change in receptor expression. This preferential reduction in the proportion of neurons bearing particular NMDAR1 isoforms, i.e. isoforms R1-a and b, and R1-1 with partial compensation through the expression of the R1-3 isoform, is more likely related to lowered proportion of binocularly activated neurons in the strabismic cat than to changes in eye dominance or the presence of amblyopia in one eye. (+info)
Monitoring of controlled accommodative esotropia.
(16/204)
PURPOSE: To ascertain an examination interval that will not increase the risk of untimely detection of decompensation of accommodative esotropia whether or not initial nonoperative treatment must be supplemented. METHODS: The records of 63 patients with controlled accommodative esotropia examined at 3- to 6-month intervals were reviewed for age at first control, the occurrence of decompensation, initial refraction and subsequent changes, and the need for increased correction of hyperopia or the addition of bifocals. RESULTS: Decompensation occurred in 11 patients, not associated with substantial refractive changes toward or away from emmetropia. No instance of decompensation occurred in the first 12 months of observation, and only 11.5% occurred within 2 years. Although 7 of these decompensated patients were among the 18 (28.6%) requiring supplemental nonoperative treatment, their mean initial hyperopia and annual refractive change did not differ significantly from the 11 patients who did not decompensate. Eight (18.6%) of 43 patients who were first controlled earlier than age 48 months later decompensated; 3 (15.0%) of 20 patients with later onset reached this outcome. CONCLUSIONS: Monitoring controlled accommodative esotropia at intervals of 9 to 12 months is adequate for most patients, at least over the first 2 years, other than those requiring treatment for associated conditions such as amblyopia. Refractive error changes and the need for supplemental treatment after initial control are not prominently associated with decompensation. Age at onset of accommodative esotropia earlier or later than 48 months did not influence rapidity of decompensation. (+info)