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PubMed2004

The effect of Seprafilm on adhesions in strabismus surgery-an experimental study.

PURPOSE: Seprafilm (Genzyme, Cambridge, MA) is a bioabsorbable membrane composed of sodium hyaluronate and carboxymethylcellulose. Adhesions occurring after strabismus surgery may affect surgical outcome. The purpose of our study was to histopathologically evaluate the influence of Seprafilm on postoperative adhesions. METHODS: Seven adult male New Zealand albino rabbits were used. The superior rectus muscle was resected 3 mm, and a fornix-based limbal conjunctival dissection was made inferonasally in both eyes. In one eye of each rabbit, Seprafilm was inserted between the conjunctiva and superior rectus and under the dissected inferonasal conjunctiva. The fellow eye of each rabbit, having undergone superior rectus resection and inferonasal conjunctival dissection without Seprafilm, served as the control group. The rabbits were killed and the eyes were enucleated at 6 weeks after surgery. Histopathological sections were analyzed for inflammation and fibrosis by staining them with hematoxylin-eosin and Masson trichrome, respectively. Inflammation and fibrosis were graded on a scale of 0 to 4. RESULTS: Compared with the control eyes, there was no significant difference with regard to inflammation either at the area of superior rectus resection or the area of conjunctival dissection (P.655 and P.157, respectively). Significantly less fibrosis occurred in the surgical areas where Seprafilm was used compared with the control group (P.046 and P.015, respectively) both at the area of superior rectus resection and the area of conjunctival dissection. CONCLUSION: This study shows that Seprafilm significantly decreases postoperative adhesions between the conjunctiva, muscle, and sclera. Application of Seprafilm may prove useful in strabismus surgery especially where adhesion formation may influence the outcome and in cases where recurrent conjunctival dissection may be needed.

Animals↗

PubMedDate not supplied

Unilateral paralytic strabismus in the adult cat induces plastic changes in interocular disparity along the visual midline: contribution of the corpus callosum.

Neurones activated through the corpus callosum (CC) in the cat visual cortex are known to be almost entirely located at the 17/18 border. They are orientation selective and display receptive fields (RFs) distributed along the central vertical meridian of the visual field ("visual midline"). Most of these cells are binocular, and many of them are activated both from the contralateral eye through the CC, and from the ipsilateral eye via the direct retino-geniculo-cortical (GC) pathway. These two pathways do not carry exactly the same information, leading to interocular disparity between pairs of RFs along the visual midline. Recently, we have demonstrated that a few weeks of unilateral paralytic strabismus surgically induced at adulthood does not alter the cortical distribution of these units but leads to a loss of their orientation selectivity and an increase of their RF size, mainly toward the ipsilateral hemifield when transcallosally activated (Watroba et al., 2001). To investigate interocular disparity, here we compared these RF changes to those occurring in the same neurones when activated through the ipsilateral direct GC route. The 17/18 transition zone and the bordering medial region within A17 were distinguished, as they display different interhemispheric connectivity. In these strabismics, some changes were noticed, but were basically identical in both recording zones. Ocular dominance was not altered, nor was the spatial distribution of the RFs with respect to the visual midline, nor the amplitude of position disparity between pairs of RFs. On the other hand, strabismus induced a loss of orientation selectivity regardless of whether neurones were activated directly or through the CC. Both types of RFs also widened, but in opposite directions with respect to the visual midline. This led to changes in incidences of the different types of position disparity. The overlap between pairs of RFs also increased. Based on these differences, we suggest that the contribution of the CC to binocular vision along the midline in the adult might be modulated through several intrinsic cortical mechanisms.

Action Potentials↗

PubMed2003

Oral clonidine premedication does not reduce postoperative vomiting in children undergoing strabismus surgery.

BACKGROUND: We evaluated the effect of oral clonidine on postoperative vomiting (POV) in children undergoing strabismus surgery. METHODS: Eighty ASA physical status I children aged 3-12 years were randomly assigned to one of two groups in a double-blinded manner. One hour before surgery, each patient in the clonidine group (n=40) received clonidine 4 micro g kg-1 in apple juice 0.2 ml kg-1, and each of the controls (n=40) received apple juice 0.2 ml kg-1 only. The protocol for general anesthesia was propofol-sevoflurane in N2O/O2. A paracetamol suppository was administered in each case to prevent postoperative pain. Patient responses during 0-48 h after anesthesia were recorded as complete (no POV, no antiemetic rescue required), retching, vomiting, or rescue antiemetic. RESULTS: There were no significant differences between the clonidine and control groups regarding the number of patients with complete response (21 vs. 18, respectively) retching (10 vs. 14, respectively), vomiting (19 vs. 22, respectively), or rescue antiemetic (9 vs. 12, respectively) during the first 48 h. CONCLUSION: Oral premedication with clonidine 4 micro g kg-1 did not reduce the rate of POV in the children undergoing strabismus surgery.

Adrenergic alpha-Agonists↗

PubMed1998

Prevalence of amblyopia with anisometropia or strabismus among schoolchildren in the Sultanate of Oman.

PURPOSE: The purpose of this study was to investigate the prevalence of common eye disorders in a nationwide school survey conducted in the Sultanate of Oman. The results presented here are those involving amblyopia induced by strabismus or anisometropia. METHODS: A random selection of primary schools provided a sample that included 49 schools with 6541 children in Grades 1 and 6. Examinations of the eyes of 96%, of these children were conducted doing visual acuity screening to 0.5. All 6292 children had an external eye examination. All children failing the visual acuity test had a complete eye examination. RESULTS: Amblyopia was found in 0.92%, strabismic amblyopia in 0.48%, anisometropic amblyopia in 0.44% and strabismus with or without amblyopia was seen in 0.9%. There was statistically significantly (p<0.05) more amblyopia in 11-12 year olds (Grade 6) when compared with the 6-7 year olds (Grade 1). This difference was only found among the strabismic children. CONCLUSION: When compared to Europe or North America the prevalence of strabismic amblyopia is lower, whereas anisometropic amblyopia occurs with approximately the same frequency. The increase of strabismic amblyopia in the older children indicates a development of amblyopia after the age of 6 to 7 years in an untreated population.

Amblyopia↗

PubMed1993

Subconjunctival bupivacaine versus topical amethocaine in strabismus surgery.

A prospective study was performed to evaluate and compare the effect of subconjunctival bupivacaine and topical amethocaine on pain relief after strabismus surgery. A total of 40 children scheduled for elective operation were randomly allocated to receive either subconjunctival bupivacaine or topical amethocaine at the end of surgery. Post-operative pain was evaluated using a four-point assessment score. We show that both techniques provide good post-operative pain relief. We advocate that either could be used routinely in strabismus surgery although topical amethocaine is easier to administer.

Administration, Topical↗

PubMed1993

Subconjunctival bupivacaine in strabismus surgery.

A prospective study was performed to assess the effect of subconjunctival bupivacaine on pain relief following strabismus surgery. A total of 36 children were randomly allocated to receive either subconjunctival infiltration of bupivacaine or normal saline at the conclusion of surgery. Post-operative pain was evaluated using a 4-point assessment score. Subconjunctival bupivacaine provided significantly better post-operative pain relief (P < 0.001). We suggest that it could be used routinely in strabismus surgery, as it improves post-operative comfort thereby facilitating day case surgery.

Bupivacaine↗

PubMed1996

Two infant vision screening programmes: prediction and prevention of strabismus and amblyopia from photo- and videorefractive screening.

Two infant vision screening programmes on total populations in the Cambridge Health District have been designed to identify manifest strabismus and strabismogenic and amblyogenic refractive errors at 7-9 months of age. The first, completed, programme used the isotropic photorefractor with cycloplegia together with a standard orthoptic examination. The second, current, programme uses the VRP-1 isotropic videorefractor to identify infants with accommodative lags which are followed up by refraction under cycloplegia. Both programmes show good agreement between infants identified at screening and retinoscopic refractions at follow-up, showing that photo- and videorefraction (with or without cycloplegia) can be effective methods for screening for ametropia in infants and young children. In each programme 5-6% of infants showed abnormal levels of hyperopia (> or = 3.5 D in any meridian), less than 1% showed anisometropia > or = 1.5 D; very few infants (0.25%) showed -3D myopia or greater. Less than 1% showed manifest strabismus. Hyperopic and anisometropic children entered a randomised controlled trial of partial refractive correction. All children identified at screening, alongside appropriate control groups, are extensively followed up to age 4 years. The first programme has found that children who were hyperopic in infancy were 13 times more likely to become strabismic, and 6 times more likely to show measurable acuity deficits by 4 years, compared with controls. Wearing a partial spectacle correction reduced these risk ratios to 4:1 and 2.5:1 respectively. The impaired acuity can be attributed, in part, to meridional amblyopia resulting from persisting astigmatism. Both hyperopic and myopic infants showed refractive changes in the direction of emmetropia between 9 months and 4 years. Wearing a partial spectacle correction did not affect this process of emmetropisation, but does provide the possibility of reducing the incidence of common pre-school vision problems.

Aging↗

PubMed1996

The neural basis of suppression and amblyopia in strabismus.

The neurophysiological consequences of artificial strabismus in cats and monkeys have been studied for 30 years. However, until very recently no clear picture has emerged of neural deficits that might account for the powerful interocular suppression that strabismic humans experience, nor for the severe amblyopia that is often associated with convergent strabismus. Here we review the effects of squint on the integrative capacities of the primary visual cortex and propose a hypothesis about the relationship between suppression and amblyopia. Most neurons in the visual cortex of normal cats and monkeys can be excited through either eye and show strong facilitation during binocular stimulation with contours of similar orientation in the two eyes. But in strabismic animals, cortical neurons tend to fall into two populations of monocularly excitable cells and exhibit suppressive binocular interactions that share key properties with perceptual suppression in strabismic humans. Such interocular suppression, if prolonged and asymmetric (with input from the squinting eye habitually suppressed by that from the fixating eye), might lead to neural defects in the representation of the deviating eye and hence to amblyopia.

Amblyopia↗

PubMed1999

The results of adjustable suture technique in paediatric strabismus surgery.

PURPOSE: Adjustable suture technique (AST) has been shown to be an effective treatment method in adult strabismus. The application of AST is not well studied in children due to potential poor cooperation during adjustment and the concern that the adjustment process can not be completed. The present series evaluates the efficacy and safety of this technique in a preselected group of children between 7 and 15 years of age. METHODS: A retrospective review of 89 consecutive children undergoing AST was completed to assess: (1) the ability to perform and complete adjustment in children; (2) the frequency of need to perform adjustment; and (3) accuracy of surgical alignment. Only patients with horizontal rectus muscle surgery were included. RESULTS: All children successfully completed the AST on the first post-operative day. Of the 89 patients, 24 (27%) required further adjustment by the AST. The mean follow-up period was 13.1 months. Fifty-three patients (60%) had previous strabismus surgery (range 1 to 5 operations). Sixty-six (74%) patients achieved successful alignment. Complications included slipped muscles in 1 case and difficulty in recession of the lateral rectus muscle in 1 patient. CONCLUSIONS: Twenty-seven per cent of the patients required post-operative adjustment. The AST achieved an overall 74% successful alignment. Application of the AST should be considered in children with horizontal deviations over age 7 years, especially in the reoperations of esotropia.

Adolescent↗

PubMed1999

Comparison of anti-emetic effects of ondansetron, metoclopromide or a combination of both in children undergoing surgery for strabismus.

This prospective, randomized and double-blinded study was designed to evaluate the anti-emetic efficacy of a combination of ondansetron and metoclopramide in 100 ASA physical status I and II children of either sex and 1-15 years of age undergoing elective surgery for strabismus. A standardized anaesthetic technique and post-operative analgesia were used for all the children. Children were divided into four groups. They received saline, metoclopromide 250 micrograms kg-1, ondansetron 150 micrograms kg-1 or a combination of metoclopramide 150 micrograms kg-1 and ondansetron 100 micrograms kg-1 intravenously immediately after the insertion of an intravenous cannulae. There were no differences between the groups in their age, gender, weight, duration of surgery, number of muscles subjected to surgery or intravenous fluids received. In the first 24 post-operative hours, 18 (72%) patients in the placebo group, 15 (60%) patients in the metoclopramide group, 10 (40%) patients in the ondansetron group and 11 (44%) patients in the combination group had nausea or vomiting. The overall incidence of post-operative nausea and vomiting was significantly (P < 0.05) lower in the combination group and in the ondansetron group compared with the placebo group. Nine (36%) patients in both the placebo and the metoclopramide groups and one (4%) patient in the ondansetron group required rescue anti-emetic treatment. None of the patients in the combination group required rescue anti-emetic and this was significantly less (P < 0.01) when compared with the placebo and the metoclopramide groups. Recovery and sedation scores were comparable in all the four groups. A combination of metoclopramide 150 micrograms kg-1 and ondansetron 100 micrograms kg-1 administered prior to surgery was not found to be more effective than ondansetron 150 micrograms kg-1 alone for the prophylaxis of nausea and vomiting following surgical repair of strabismus in paediatric patients.

Adolescent↗

PubMed1999

Combination of granisetron and droperidol for the prevention of vomiting after paediatric strabismus surgery.

This study was undertaken to compare the efficacy of granisetron plus droperidol with each antiemetic alone for the prevention of vomiting after paediatric strabismus surgery. In a prospective, randomized, double-blinded trial, 120 ASA physical status I children, aged 4-10 years, received granisetron 40 microg.kg- 1, droperidol 50 microg.kg- 1, granisetron 40 microg.kg- 1 plus droperidol 50 microg.kg- 1 (n=40 of each) intravenously after an inhalation induction of anaesthesia. A complete response, defined as no vomiting, no retching and no need for another rescue antiemetic medication, during 0-3 h after anaesthesia was 80% with granisetron, 45% with droperidol and 98% with granisetron plus droperidol, respectively; the corresponding incidence during 3-24 h after anaesthesia was 78%, 38% and 98% (P< 0.05; overall chi-squared test with Yates continuity correction). No clinically important adverse events were observed in any of the groups. In conclusion, a combination of granisetron and droperidol was more effective than granisetron or droperidol as a sole antiemetic for the prevention of postoperative vomiting in children undergoing strabismus repair.

Analysis of Variance↗

PubMed1999

Incidence of nausea and vomiting in children after strabismus surgery following desflurane anaesthesia.

In a prospective, randomized parallel study, 60 ASA I-III children aged 1-17 years, scheduled for elective strabismus surgery, were anaesthetized with desflurane without prophylactic antiemetic medication. The objective of the study was to determine the incidence of postoperative nausea and vomiting after general anaesthesia with desflurane. To decide whether nitrous oxide further influences these symptoms, the patients were randomly assigned to two groups of 30 patients each. One group received desflurane in oxygen/air and a second group received desflurane in oxygen/nitrous oxide. In all children, after intravenous induction and tracheal intubation, anaesthesia was administered as minimal flow anaesthesia with oxygen and nitrous oxide or air according to the random plan. The patients were observed for 48 postoperative hours until their discharge from the ward. The overall incidence of nausea was found to be 37%, and vomiting was seen in 32% of all patients. No statistical correlation was found between the incidence of postoperative emesis and the administration of nitrous oxide or the duration of general anaesthesia. Instead, the incidence of vomiting was 2.5-fold higher when surgery was performed on both eyes compared with one eye. The relatively low incidence of postoperative nausea and vomiting, as well as the quick recovery from anaesthesia, permitting an early discharge from the postoperative care unit to the ward, show desflurane to be a suitable volatile anaesthetic in strabismus surgery in children.

Adolescent↗

PubMed2001

The efficacy of oral clonidine premedication in the prevention of postoperative vomiting in children following strabismus surgery.

We evaluated the efficacy of clonidine given orally preoperatively for preventing postoperative vomiting (POV) in children undergoing propofol-nitrous oxide anaesthesia for strabismus surgery. Sixty children, ASA physical status I, aged 2-12 years, received diazepam, 0.4 mg x kg(-1) or clonidine, 4 microg x kg(-1) (n=30 each) orally, in a randomized double-blind manner. These drugs were given 105 min before an inhalational induction of anaesthesia. A complete response, defined as no POV and no need for rescue antiemetic medication, during 0-24 h after anaesthesia was 67% with diazepam and 93% with clonidine, respectively (P=0.024). No clinically adverse event was observed in any of the groups. In summary, pretreatment with oral clonidine enhances the antiemetic efficacy of propofol for the prevention of POV after paediatric strabismus surgery.

Administration, Oral↗

PubMed2003

Dolasetron for the prevention of postoperative vomiting in children undergoing strabismus surgery.

BACKGROUND: Children undergoing strabismus surgery have a high incidence of postoperative vomiting (POV). The purpose of this study was to assess the efficacy and safety of dolasetron for the prevention of emesis comparing a single 0.35 mg.kg-1 or 12.5 mg dose with placebo. METHODS: Children aged 2-12 years with an ASA status of 1 or 2 undergoing strabismus surgery were randomized in a double-blind manner to one of three treatment groups. Patients were excluded with a history of previous postoperative vomiting or motion sickness, allergy to serotonin receptor antagonists or previous antiemetic administration within 24 h prior to enrollment. General anaesthesia was induced with sevoflurane and N2O/O2 and maintained with isoflurane and N2O/O2. The study medication was administered 15 min prior to the end of surgery. Patients experiencing two or more episodes of vomiting were rescued in the postanaesthesia care unit (PACU) with metoclopramide 0.15 mg.kg-1. A total of 118 patients were enrolled with documentation of the number and severity of vomiting episodes, time to awakening, PACU length of stay and postoperative agitation. RESULTS: Patients with an acute complete response (ACR), defined as no emetic episodes and no rescue medication within 24 h of study drug administration were 62% (weight dose), 64% (fixed dose) and 33% (placebo, P < 0.05). CONCLUSIONS: There was no statistical difference between the 0.35 mg.kg-1 dose and the fixed 12.5 mg dose of dolasetron with both reducing the incidence of POV.

Acetaminophen↗

PubMed2000

[Strabismus, hemianopsia and the sundial of Mawas and Franceschetti].

UNLABELLED: THE ARTIFACT: The artifact is a light rectangular slate of black cardboard showing two white lines at 40 degrees angle. It provokes physiological diplopia in lateral vision. BACKGROUND: In normal subjects, the right oblique line stimulates the right nasal hemiretina, perceived as an oblique line, and the left temporal hemiretina, perceived as a vertical line, both lines being on the right hand side. Likewise, the left oblique line is seen as two lines on the left hand side. The 4 lines form and M and a W combined. The strabismus subject sees 3 lines for he neutralizes one; the alternating squint sees only 2; the heterophoric sees 4 lines, two of which blurred, and the hemianopic sees only part of the dial. RESULTS: The subject must select the image he sees from an array of possibilities shown on the back of the dial. From 5 years of age on, normal subjects select the [symbol: see text] or the "butterfly"; hemianopic subjects correctly describe the loss of either the left or right field. CONCLUSIONS: The sundial facilitates both the screening and the treatment of binocular vision disorders. Bangerter's hemifilter will be used in association with exercises for physiological diplopia at home under monthly orthoptic control. All this made it possible to obtain useful peripheral fusion in early onset strabismus.

Diplopia↗

PubMed2004

[Strabismus surgery in Grave's disease--dose-effect relationships and functional results].

BACKGROUND: Strabismus in thyroid ophthalmopathy is based on a loss of the contractility and distensibility of the external ocular muscles. Different therapeutic approaches are available, such as recession after pre-. or intraoperative measurement, adjustable sutures, antagonist resection, or contralateral synergist faden-operation. PATIENTS AND METHODS: 26 patients with strabismus in thyroid ophthalmopathy were operated between 2000 and 2003. All patients were examined preoperatively, then 1 day and 3 - 6 months (maximum 36 months) postoperatively. Before proceeding with surgery, we waited at least 6 months after stabilization of ocular alignment and normalization of thyroid chemistry. RESULTS: Preoperative vertical deviation was 10-44 PD (mean 22), 3 months postoperatively it was 2-10 PD (mean 1.5). Recession of the fibrotic muscle leads to reproducible results: 3.98 +/- 0.52 PD vertical deviation/mm for the inferior rectus. In the case of a large preoperative deviation a correction should be expected, which might not be sufficient in the first few days or weeks; a second operation should not be carried out before 3 months. 7 patients were operated twice, 1 patient need three operations. 4 patients (preop. 0) achieved no double vision at all; 15 patients (preop. 1) had no double vision in the primary and reading positions; 3 patients (preop. 0) had no double vision with a maximum of 5 PD; 1 patient (preop. 7) had double vision in the primary or reading position even with prisms; and 2 patients (preop. 17) had double vision in every position. CONCLUSIONS: We advocate that recession of the restricted inferior or internal rectus muscle is precise, safe and effective in patients with thyroid ophthalmopathy. The recessed muscle should be fixed directly at the sclera to avoid late over-correction through a slipped muscle. The success rate in terms of binocular single vision was 76 % and 88 % with prisms added.

Adult↗

PubMed2006

[Adaptation of visual distortions in children with strabismic amblyopia following strabismus surgery and occlusion therapy].

BACKGROUND: Reduced visual acuity and deficient binocularity are well-known symptoms of amblyopia. Distortions of visual space perception were reported more recently in strabismic amblyopia. This study investigated whether strabismus surgery and occlusion therapy have an influence on these deficits in amblyopic children. MATERIALS AND METHODS: Two aspects of vertical alignment of amblyopic eyes, namely spatial distortion and spatial uncertainty, were investigated prospectively in 13 children (mean age 6 years 9 months) before and after strabismus surgery and in 12 children (mean age 6 years 11 months) during 6 months of occlusion therapy. RESULTS: A different impact of the two types of therapeutic intervention was observed: a slight (statistically not significant) increase of uncertainty was the only change noticed postoperatively after 1 week, spatial distortions were not affected. During occlusion treatment, both clear shifts of alignment and a decrease of uncertainty occurred. CONCLUSIONS: The geometry of visual space of amblyopic children showed modifications due to altered visual experience during treatment, most obviously during occlusion therapy. These changes are evidence for unknown features of plasticity of the amblyopic visual system initiated by treatment.

Amblyopia↗

PubMed1986

[Dynamics of eye movements in paralytic strabismus].

The characteristic clinical signs of paralytic strabismus can be confounded by phenomena concerning either the ipsilateral and/or the contralateral eye, the latter particularly occurring when fixating with the paretic eye. Specific clinical and EOG-phenomena and the underlying dynamic mechanisms of the peripheral oculomotor apparatus in acute and chronic paralytic strabismus are described.

Abducens Nerve↗