Attention in visually typical and amblyopic children
Amblyopia is a cortical visual disorder caused by unequal visual input to the brain from the two eyes during development. Amblyopes show reduced visual acuity and contrast sensitivity and abnormal binocularity, as well as more "global" perceptual losses, such as figure-ground segregation and global form integration. Currently, there is no consensus on the neural basis for these higher-order perceptual losses. One contributing factor could be that amblyopes have deficiencies in attention, such that the attentional processes that control the selection of information favor the better eye. Previous studies in amblyopic adults are conflicting as to whether attentional deficits exist. However, studies where intact attentional ability has been shown to exist were conducted in adults; it is possible that it was acquired through experience. To test this hypothesis, we studied attentional processing in amblyopic children. We examined covert endogenous attention using a classical spatial cueing paradigm in amblyopic and visually typical 5- to 10-year old children. We found that all children, like adults, independently of visual condition, benefited from attentional cueing: They performed significantly better on trials with an informative (valid) cue than with the uninformative (neutral) cue. Response latencies were also significantly shorter for the valid cue condition. No statistically significant difference was found between the performance of the amblyopic and the visually typical children or between dominant and nondominant eyes of all children. The results showed that covert spatial attention is intact in amblyopic and visually typical children and is therefore not likely to account for higher-order perceptual losses in amblyopic children.
The Role of Superior Oblique Posterior Tenectomy Along With Inferior Rectus Recessions for the Treatment of Chin-up Head Positioning in Patients With Nystagmus
PURPOSE/OBJECTIVE:To evaluate the clinical outcomes of bilateral superior oblique posterior 7/8th tenectomy with inferior rectus recession on improving chin-up head positioning in patients with horizontal nystagmus. METHODS:Medical records were reviewed from 2007 to 2017 for patients with nystagmus and chin-up positioning of 15Â° or more who underwent combined bilateral superior oblique posterior 7/8th tenectomy with an inferior rectus recession of at least 5 mm. RESULTS:Thirteen patients (9 males and 4 females) were included, with an average age of 7.3 years (range: 1.8 to 15 years). Chin-up positioning ranged from 15Â° to 45Â° degrees (average: 30Â°). Three patients had prior horizontal muscle surgeries, 1 for esotropia and 2 for horizontal null zones causing anomalous face turns. Ten patients underwent other concomitant eye muscle surgery: 3 had esotropia, 1 had exotropia, and 2 had biplanar nystagmus null point requiring a horizontal Anderson procedure. Four patients underwent simultaneous bilateral medial rectus tenotomy and reattachment. All patients had improved chin-up positioning. Eight patients had complete resolution, whereas 5 had minimal residual chin-up positioning. Three patients developed an eccentric horizontal gaze null point with compensatory anomalous face turn with onset 2 weeks, 2 years, and 3 years postoperatively. Average follow-up was 42.7 months. No postoperative pattern deviations, cyclodeviations, or inferior oblique overaction were seen. No surgical complications were noted. CONCLUSIONS:Bilateral superior oblique posterior 7/8th tenectomy in conjunction with bilateral inferior rectus recession is a safe and effective procedure for improving chin-up head positioning in patients with horizontal nystagmus with a down gaze null point. [J Pediatr Ophthalmol Strabismus. 201X;XX(X):XX-XX.].
The Role of Superior Oblique Posterior Tenectomy Combined with Inferior Rectus Recession for the Treatment of Chin Up Head Positioning in Patients with Nystagmus [Meeting Abstract]
Esotropia associated with high myopia
PURPOSE OF REVIEW: The aim of the present article is to describe the pathophysiology of esotropia associated with high myopia, commonly known as heavy eye syndrome, and discuss the preoperative evaluation and surgical options in these complex patients. RECENT FINDINGS: Numerous studies have looked to determine the cause of esotropia in patients with high myopia. Orbital imaging has shown a nasal displacement of the superior rectus muscle and an inferior displacement of the lateral rectus muscle. As such, traditional resection-recession surgery can be ineffective in these patients. Instead, correcting the deviant muscles paths is necessary. Recent studies have shown that loop myopexy with or without medial rectus recession can be performed without sclera fixation sutures to correct the underlying pathophysiology. SUMMARY: Heavy eye syndrome or strabismus fixus is a rare restrictive strabismus. Careful preoperative evaluation must be performed in order to correctly diagnose these patients. If posterior globe prolapse with superior and lateral rectus muscle displacement is seen, loop myopexy can be a well tolerated and effective procedure in treating heavy eye syndrome.
Effect of Superior Oblique Posterior 7/8ths Tenectomy on Anomalous Head Positioning in Patients with Brown Syndrome [Meeting Abstract]
Bilateral posterior tenectomy of the superior oblique muscle for the treatment of A-pattern strabismus
PURPOSE: To evaluate the efficacy of bilateral posterior superior oblique tenectomy for the treatment of A-pattern strabismus due to superior oblique overaction regardless of the magnitude of the pattern. METHODS: The medical records of patients with A-pattern esotropia or exotropia in the presence of superior oblique overaction who underwent combined horizontal muscle surgery along with bilateral superior oblique posterior 7/8 tenectomy from 2003 to 2013 were retrospectively reviewed. Patients with at least 3 months' follow-up were included. RESULTS: A total of 73 patients were included. Of these, 46 had esotropia; 27, exotropia. The preoperative A-pattern deviation for the study population was 19.6Delta +/- 11.4Delta (range, 10-60), with a final postoperative patten collapse of 18.2 +/- 3.6. Superior oblique overaction was 2.3 +/- 0.7 preoperatively and 0.3 +/- 0.7 postoperatively. Overall, 87.7% of patients had a successful collapse of their pattern to <10Delta following the initial bilateral superior oblique posterior tenectomy, with an additional 4.1% following a second procedure. Of patients with a pattern deviation of <25Delta, 87.9% had successful collapse of the pattern following 1 surgery, and 86.7% of patients who had a pattern of >/=25Delta had successful collapse. Postoperatively, 7 patients demonstrated mild inferior oblique overaction. No surgical complications were noted. CONCLUSIONS: A uniform dose of bilateral posterior 7/8 tenectomy surgery successfully collapses A-pattern deviations of all magnitudes.
Musical chairs mortality functions: density-dependent deaths caused by competition for unguarded refuges
Structural refuges within which prey can escape from predators can be an important limiting resource for the prey. In a manner that resembles the childhood game of musical chairs, many prey species rapidly retreat to shared, unguarded refuges whenever a predator threatens, and only when refuges are relatively abundant do all prey individuals actually escape. The key feature of this process is that the per capita prey mortality rate depends on the ratio of prey individuals to refuges. We introduce a new class of mortality functions with this feature and then demonstrate statistically that they describe field mortality data from a well-studied coral reef fish species, the Caribbean bridled goby Coryphopterus glaucofraenum, substantially better than do several mortality functions of more conventional form
Treatment of capillary hemangiomas causing refractive and occlusional amblyopia
PURPOSE: Capillary hemangiomas of the eyelid and orbit are treated when amblyopia secondary to anisometropic astigmatism or pupillary occlusion is present or when rapid growth of the hemangioma threatens to occlude the pupil. The goal of this study was to determine whether treatment of hemangiomas resolves or prevents occlusion or results in decrease in astigmatism. METHODS: The records of 54 patients who underwent treatment for reduction in the size of a capillary hemangioma causing amblyopia or threatened amblyopia in two pediatric ophthalmology practices were reviewed. RESULTS: Twenty-eight patients were treated for amblyopia due to anisometropic astigmatism. The average amount of pretreatment astigmatism was 2.71 D, while the average amount of post-treatment astigmatism was 0.46 D. Fifteen of these patients could be tested for optotype visual acuity and all had vision acuity of 20/40 or better. Only 1 of the 15 patients treated for threatened occlusion of the pupil developed occlusion. Six of these patients cooperated with optotype visual acuity and all had vision acuity of 20/30 or better. Eleven patients were treated for pupillary occlusion. Occlusion resolved in all cases. Of the five patients treated for occlusion who cooperated with optotype visual acuity, two had a vision acuity of 20/100 or worse. CONCLUSIONS: Treatment to reduce the size of capillary hemangiomas results in resolution of occlusion, reduction in astigmatism, and prevention of pupillary occlusion. Those with occlusion are at higher risk for severe residual amblyopia and require prompt and definitive treatment
Surgical treatment of capillary hemangiomas causing amblyopia
BACKGROUND: Capillary hemangiomas of the eyelids and orbit can cause refractive and occlusive amblyopia. Although oral and intralesional steroid injections are the most common treatment modalities, sometimes they are not successful. There is a paucity of information in the literature on the success of eliminating amblyogenic factors by treating these lesions with surgical resection. METHODS: Retrospective chart review of 10 patients in two pediatric ophthalmology practices who underwent surgical excision of a capillary hemangioma that was causing amblyopia and that had failed to regress with other treatment. RESULTS: Two patients had surgery secondary to pupillary occlusion, which was successful in relieving occlusion. Eight patients had surgery secondary to significant astigmatism. The average preoperative astigmatic difference between the affected and unaffected eye in five of these patients undergoing surgery before the age of 21 months was 2.15 D. The average postoperative astigmatic difference was 0.1 D. The average preoperative astigmatic difference between the affected and unaffected eye in three patients undergoing surgery after 21 months of age was 1.6 D. Surgery completely failed to reduce the astigmatism in two of these patients. The third patient had a decrease of 0.75 D of cylinder but still had a difference of 1.75 D between the two eyes postoperatively. Postoperative complications in this study included wound infection in one patient. CONCLUSIONS: Surgical excision of capillary hemangiomas that were resistant to other modes of treatment was useful in relieving pupillary occlusion and in decreasing the amount of astigmatism if performed before the age of 21 months in our series of patients. Our cases as well as the literature suggest that surgery should be performed at 13 months or earlier to reduce the amount of astigmatism
Axillary cannulation for proximal aortic surgery is as safe in the emergent setting as in elective cases
BACKGROUND: Right axillary artery cannulation and selective antegrade cerebral perfusion (SCP) have become well-described strategies in the surgical treatment of proximal aortic disease. Many series report increases in adverse outcomes with SCP used in emergent settings. We compare outcomes in elective and emergent patients. METHODS: Over 21 months, SCP through right axillary cannulation with a side graft was performed in 61 patients. Thirty-three percent (20 of 61) underwent emergent operation for Stanford type A dissection or intramural hematoma, including 3 of 20 (4.7%) with pericardial tamponade; the remainder of SCP (41 of 61) was elective. The mean follow-up was 9.1 +/- 0.40 months. RESULTS: Selective antegrade cerebral perfusion was used in 20 of 22 emergent cases (91%), with 2 unsuccessful cannulation attempts, and no peripheral arterial dissections encountered. The SCP flows averaged 16.3 +/- 0.71 cc x kg(-1) x min(-1) for a mean perfusion period of 26.1 +/- 1.9 minutes. The average cardiopulmonary bypass time for all patients was 173 +/- 11 minutes. Average hospital stay was 8.1 +/- 0.80 days. One case (1.3%) of permanent and 3 cases (4.8%) of temporary neurologic dysfunction occurred in SCP patients. The hospital mortality rate for emergent SCP cases (2 of 20, 10%) was not statistically different from the mortality rate for elective SCP cases (3 of 41, 7.3%, p = not significant), with no difference in complication rates. All 3 SCP patients with preoperative tamponade survived without complication. Cerebral oximetry data showed a trend toward decreased left-sided (contralateral) scalp perfusion. There was no association of emergent status with neurologic dysfunction, death, or any other adverse outcome. CONCLUSIONS: Axillary cannulation and SCP in the surgical treatment of proximal aortic pathology is safe in both elective and emergent settings