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PubMed1977

An attempt to assess the effects of monocular deprivation and strabismus on synaptic efficiency in the kitten's visual cortex.

The relative effectiveness of the two eyes in exciting cells in the visual cortex was assessed, using both natural stimulation and electrical stimulation of the optic discs. It is is argued that supramaximal electrical stimulation of the optic nerve could possibly reveal 'subliminal' synaptic inputs even after monocular deprivation or artificial strabismus has caused a loss of natural input from that eye, if such 'silent' synaptic input still survives. However, in kittens monocularly deprived for various periods of time or made artificially strabismic, there was usually excellent agreement between the relative visual excitability in the two eyes and their relative electrical excitability. In one animal, monocularly deprived continuously until 23 weeks of age, we examined the effect of reversibly turning off signals from the normal eye by pressure blinding. There was no evidence of a very rapid return of sensitivity to either electrical or natural stimulation of the deprived eye.

Animals↗

PubMed1976

Experimental suture studies in strabismus surgery. I. Reattachment rate of extraocular muscles after recession and resection operations.

We described a method for measuring the in vivo tensile strength of the muscle-scleral junction in rabbits. Data obtained on the reattachment time of extraocular muscles after recession and resection operations indicate the rate of healing is similar for both operations. Adequate wound healing is present by the 5th day after surgery, and sutures are probably unnecessary after 8 to 9 days. An ideal suture for strabismus surgery would be one that retains its strength during the first 8 to 9 days following surgery, then undergoes rapid absorption.

Animals↗

PubMed1976

Experimental suture studies in strabismus surgery. II. Comparison of tensile strength of plain catgut with polyglycolic acid (Dexon) sutures after extraocular muscle surgery.

From our experimental studies it appears Dexon satisfies more of the criteria for an ideal suture for strabismus surgery than plain catgut for the following reasons. Its handling, tying, and knot-holding (if tighthened firmly) qualities are excellent. Tissue reaction is minimal. It seems to be non-antigenic. Of paramount importance. Dexon's tensile strength is high initially and it retains its strength through the critical period of muscle-scleral wound healing, then dissolves in a rapid uniform manner.

Animals↗

PubMed1976

[A contribution for recording data in strabismus (author's transl)].

The recording of the data of all investigations in strabismus concomitans convergens is done by a formular, which is presented in this paper (Fig. 1). The data code is printed on the backside (Fig. 2). It is possible to evaluate the results with this formular in a computer by punch cards. A quick information without computer help is possible as well. The methods of recording data used by different authors are explained and the advantages and disadvantages are discussed.

Computers↗

PubMed1976

[Results of surgical treatment in strabismus convergens (author's transl)].

In 252 patients with strabismus concomitans convergens the surgical method of the combined medial rectus recession and lateral rectus resection (Fig. 1) was studied retrospectively. The reduction of the deviation was compared with the added displacement of both muscles (Figs. 2 and 3) or the displacement of one single muscles (Table 1 and 2). Fig. 4 shows the relation between the recession-resection and the reduction of the deviation. A formula for this reduction (Z) is given: Z=6.7 chi recession (in mm) + 2.2 chi resection (in mm) - 8.1. In long the recession is 3 times more effective than the resection. In 61.5% of the patients the eyes stood parallel after surgery or a residual deviation up to 5 degrees was achieved. There was a little difference in the total results of the first (1 week) and the second (6 months) postoperative control. Major differences occurred when comparing single data.

Child↗

PubMed1993

Stereoscopic cooperation between the fovea of one eye and the periphery of the other eye at large disparities. Implications for anomalous retinal correspondence in strabismus.

In normal human observers we searched for the largest amount of visual disparity that can still provide depth information; we compared (1) crossed and uncrossed disparities and (2) symmetrical and asymmetrical locations of disparate stimuli. A pair of 3 degrees discs projected for 100 ms served as targets. Symmetrical stimuli were projected on temporal or nasal retinal loci in both eyes; asymmetrical stimuli were projected on the fovea of one eye and on the nasal or temporal periphery of the other eye. Thresholds were determined using a two-alternative forced choice procedure. Subjects had to distinguish binocular disparate images from monocular double images of identical angular separation. Among six subjects, crossed disparities were recognized by one up to 6 degrees, by three up to 9 degrees, by one up to 18 degrees, and by one up to 21 degrees. Uncrossed disparities were recognized by two at 3 degrees, by two up to 6 degrees and by two up to 9 degrees. Hence, crossed disparities could be recognized up to higher angles than uncrossed. No consistent difference was found between symmetrical and asymmetrical stimuli. Stimuli with crossed disparity appeared smaller and with uncrossed disparity larger than monocular stimuli of the same objective size, suggesting that the size-constancy mechanism operates when disparity stimuli are presented as briefly as 100 ms, i.e., without simultaneous vergence eye movements. We speculate that the far-reaching interocular connections demonstrated in normal subjects might also be utilized in the case of strabismus: these interocular connections could form the basis for anomalous retinal correspondence.

Adult↗

PubMed1993

Reversible mydriasis during strabismus surgery in children.

A study was made of changes in pupil diameter during strabismus surgery performed on 84 children aged from 1 to 12 years. Several factors influencing the appearance of reversible changes in pupil diameter during surgery were examined. The pupil diameters of both eyes were inspected during the course of the operation, and the reactions of manipulated eyes were compared to those of the non-manipulated eyes. Two types of general anesthesia were used, inhalation anesthesia and combined intravenous-inhalation anesthesia, depending upon the patient's body weight. Patient's age and sex, type of anesthesia, surgical procedure and the manipulated eye muscles were documented. The study demonstrated that mydriasis did not occur in patients operated under combined intravenous-inhalation anesthesia, while 74% of those operated solely under inhalation anesthesia developed mydriasis. This mydriasis only occurred during surgical manipulation of the eye muscles. The amount of traction on the other muscles, and the depth of anesthesia were not related to pupil diameter.

Age Factors↗

PubMed1988

Stereotest artifacts and the strabismus patient.

A new use of nonstereoscopic cues in stereopsis testing is described. It consists of alternation of fixation while observing for image jump in the disparate portions of the test target. This may enable some stereoblind strabismus patients to achieve artifactually good stereotest scores and explain those patients who appear to have gross stereopsis on the Titmus test, but are unable to perform any random-dot test of stereopsis. A new stereotest is described which does not resort to a random-dot format and yet is free from lateral displacement and alternation cues.

Adult↗

PubMed1988

Infantile exotropia with homonymous hemianopia: a rare contraindication for strabismus surgery.

A homonymous hemianopia can be compensated by a strabismus in the direction of the visual field defect if the deviated eye has a harmonious anomalous localization. This compensation is only partial; its extent corresponds to the angle of deviation. We report on two patients with a hemianopia to the left. Under binocular conditions the visual field defect was reduced by an exotropia of the left eye with panoramic vision. Unfortunately, up to now it has not been possible to induce such a sensory-motor compensation in cases of homonymous hemianopia with normal retinal correspondence in an adult visual system.

Adult↗

PubMedDate not supplied

The prognostic value of visual evoked response latency in the treatment of amblyopia caused by strabismus.

Visual evoked response alterations and especially P100 latency were studied in 60 patents with amblyopia caused by strabismus. Patients were divided in two groups according to the mode of fixation of the strabismic eye. Group A included patients with eccentric fixation, and group B, patients with central fixation of the strabismic eye. In all cases visual evoked responses were recorded before and after a 6-month period during which the patients had full-time occlusion of the sound eye. In cases with eccentric fixation of the strabismic eye, P100 latency was more abnormal than in cases with central fixation. In cases where latencies are clearly abnormal before treatment, the prognosis is poor and the results after occlusion of the sound eye are unstable. In contrast, in the cases with normal or nearly normal visual evoked response latencies, the prognosis is better, and these eyes show satisfactory improvement of visual acuity.

Amblyopia↗

PubMed1982

Strabismus as a possible sign of subclinical muscular dystrophy predisposing to rhabdomyolysis and myoglobinuria: a study of an affected family.

Administration of succinylcholine to normal individuals results in alterations in muscle membrane integrity expressed as a slight increase in the concentrations of creatine phosphokinase (CK) in serum and appearance of small amounts of myoglobin in the urine, but without clinical symptoms. Subjects with strabismus due to congenital muscular dystrophy may develop more significant rhabdomyolysis expressed as muscle stiffness and weakness, massive myoglobinuria, marked elevation of serum CK and other enzymes, metabolic acidosis, tachycardia and moderate elevation of body temperature. In some cases grave malignant hyperthermia with significant hypoxia, metabolic acidosis, tachycardia and marked abnormalities in serum electrolyte concentrations may cause irreversible damage to the central nervous system and other vital organs and death. A case of difficult anaesthesia for a six year old boy belonging to family affected with muscular dystrophy is presented. More attention must be given to preoperative examination (anamnesis, serum enzymes) or ophthalmological patients and more careful monitoring during anaesthesia and in the early postoperative period must be instituted to prevent and treat complications induced by succinylcholine and volatile anaesthetic agents.

Child↗

PubMed1991

Scopolamine patch reduces postoperative emesis in paediatric patients following strabismus surgery.

Scopolamine patch was evaluated for the prevention of postoperative emesis in 50 children undergoing strabismus surgery. All subjects were premedicated, with none receiving narcotic premedicants. Anaesthesia included controlled ventilation with the use of muscle relaxants, atropine, and halothane. Before operation, the subjects were randomly assigned to one of two groups: a treatment group received a scopolamine patch at a dose of either 0.75 mg or 0.375 mg, and a control group received no patch. Both the incidence and frequency of vomiting in the scopolamine-treated group were significantly (P less than 0.05) lower than in the control group.

Administration, Cutaneous↗

PubMed1991

Antiemetic prophylaxis with promethazine or droperidol in paediatric outpatient strabismus surgery.

This randomized, double-blind study evaluated the antiemetic efficacy and the side-effects of promethazine pretreatment (0.5 mg.kg-1 IV + 0.5 mg.kg-1 IM) versus droperidol + placebo pretreatment (droperidol, 0.075 mg.kg-1 IV + physiological saline, 0.02 ml.kg-1 IM). One hundred unpremedicated ASA physical status I children ranging from two to ten years, and undergoing outpatient strabismus surgery were studied. All children received inhalational anaesthesia with halothane, nitrous oxide and oxygen. Neither opioids nor muscle relaxants were used. The incidence of vomiting and/or retching and the incidence of side-effects were determined in the post-anaesthesia recovery room (PARR), in the short-stay surgical unit (SSSU), and after discharge from the hospital (including the journey and the stay at home during the first postoperative day). Promethazine and droperidol were equally effective in reducing the incidence of vomiting before discharge to two and eight per cent respectively. On the contrary, the incidence of vomiting after discharge and overall were significantly less with promethazine (ten and ten per cent) than with droperidol pretreatment (54 and 56 per cent) (P less than 0.0001). Promethazine permitted the time to discharge from the hospital to be reduced to an average of three hours, without increasing the incidence of vomiting postdischarge. Promethazine pretreatment is much less expensive than droperidol pretreatment. The incidence of restlessness was significantly less with droperidol (eight per cent) than with promethazine (36 per cent) (P less than 0.001). Promethazine pretreatment demands the use of an analgesic like acetaminophen in order to reduce the incidence of postoperative pain and restlessness.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory Surgical Procedures↗

PubMed1993

Propofol anaesthesia reduces early postoperative emesis after paediatric strabismus surgery.

Propofol anaesthesia may reduce postoperative emesis. The purpose of this study was to compare the incidence of emesis after propofol anaesthesia with and without nitrous oxide, compared with thiopentone and halothane anaesthesia, in hospital and up to 24 hr postoperatively, in outpatient paediatric patients after strabismus surgery. Seventy-five ASA class I or II, unpremedicated patients, aged 2-12 yr were randomly assigned to one of three groups: Thiopentone, 6.0 mg.kg-1 i.v. induction followed by halothane and N2O/O2 for maintenance (T/H); propofol for induction, followed by propofol and oxygen for maintenance (P/O2); and propofol for i.v. induction, followed by propofol infusion and N2O/O2 for maintenance (P/N2O). All received vecuronium, controlled ventilation, and acetaminophen pr. Morphine was given as needed for postoperative analgesia. There were no differences in age, weight, number of eye muscles operated upon, duration of anaesthesia or surgery. The P/N2O group (255 +/- 80 micrograms.kg-1 x min-1) received less propofol than the P/O2 group (344 +/- 60 micrograms.kg-1 x min-1) (P < or = 0.0001) and had shorter extubation (P < 0.001) and recovery (P < 0.01) times. Emesis in the hospital, in both the P/N2O (4.0%) and P/O2 group (4.0%) was less than in the T/H group (32%) (P < 0.01). Antiemetics were required in four patients in the T/H group (16.0%). Overall emesis after surgery was not different among the groups: T/H (48%), P/O2 (28%) and P/N2O (42%). The use of propofol anaesthesia with and without N2O decreased only early emesis. This supports the concept of a short-acting, specific antiemetic effect of propofol.

Ambulatory Surgical Procedures↗

PubMed1988

Postoperative vomiting following strabismus surgery in paediatric outpatients: spontaneous versus controlled ventilation.

The study was designed to compare the frequency and severity of postoperative vomiting in paediatric out-patients receiving controlled ventilation (IPPV) or breathing spontaneously (SV) during anaesthesia for strabismus repair. One hundred and twenty unpremedicated children (ages 2-12 years) were studied in a randomized fashion. After intravenous induction of anaesthesia and tracheal intubation, patients breathed halothane 1-1.5 per cent inspired and N2O 66 per cent in O2 spontaneously (n = 60), or received IPPV, halothane 0.5-1 per cent, N2O 66 per cent, and pancuronium 0.05 mg.kg-1, which was reversed with neostigmine and atropine (n = 60). The incidence of vomiting with SV was 50 per cent (95 per cent confidence limits: 34.5-65.5 per cent) compared with 40 per cent (24.5-55.5 per cent) with IPPV (p greater than 0.25). Patients in the SV group experiencing emesis had longer operations than those not vomiting (mean +/- SEM = 1.5 +/- 0.1 vs 1.2 +/- 0.1 hours, p less than 0.005). This was not the case with IPPV. There was no correlation between age, sex, duration of surgery, or number of extraocular muscles repaired, and frequency or severity of vomiting or time to discharge. No significant advantage was afforded by IPPV over SV in the present study.

Child↗

PubMed1988

The effect of preoperative oral droperidol on the incidence of postoperative emesis after paediatric strabismus surgery.

Most children vomit after strabismus surgery. Administration of intravenous droperidol to unpremedicated paediatric patients following induction but prior to eye manipulation markedly reduces the incidence of postoperative emesis. This study tested the hypothesis that even earlier administration of droperidol, orally as a component of an oral premedication, would further reduce the incidence of postoperative emesis in this group of patients. Sixty-five patients were randomized into three premedication groups. One group received the standard oral premedication used for all outpatients at our institution (meperidine 1.5 mg.kg-1, diazepam 0.15 mg.kg-1, atropine 0.02 mg.kg-1). In the other two groups, droperidol in a dose of 50 or 75 micrograms.kg-1 was substituted for the diazepam. Droperidol-treated groups demonstrated a significantly lower incidence of vomiting prior to hospital discharge compared to the groups that received the standard oral premedication (standard--73 per cent, 50 micrograms.kg-1 droperidol--33 per cent, 75 micrograms.kg-1 droperidol--36 per cent) without prolonging hospital stay.

Administration, Oral↗

PubMed1986

Nausea and vomiting after strabismus surgery in preschool children.

The incidence of nausea and vomiting after strabismus surgery was studied in 64 children aged one to six years. Incidence was determined in the post-anaesthesia recovery room (PARR), in the same day surgery (SDS) unit, and at home on days one and two after the operation. After induction of anaesthesia, the children received an intravenous injection of droperidol (50 micrograms . kg-1) or saline in a double-blind randomized fashion, and an intravenous injection of glycopyrrolate (7.5 micrograms . kg-1) or atropine (10 micrograms . kg-1) in an open randomized fashion. The incidence of emetic symptoms was highest in the SDS unit and at home on day one. Droperidol slightly but significantly delayed awakening and was not, at least in this particular age group, associated with any difference in postoperative sickness. Despite theoretical advantages, glycopyrrolate offered no significant benefit over atropine as far as postoperative emesis was concerned.

Anesthesia, General↗

PubMed1999

Oral granisetron for strabismus surgery in children.

PURPOSE: To determine the efficacy of oral granisetron in preventing postoperative vomiting (POV) following strabismus repair in children. METHODS: In a randomized, double-blind, placebo-controlled trial, 73 pediatric patients received either placebo, 20 micrograms.kg-1 or 40 micrograms.kg-1 granisetron po 20 min before induction of anesthesia. No premedication was given, induction was with halothane and all children breathed spontaneously via a laryngeal mask airway. Maintenance was with isoflurane without the use of opioids. Ketorolac and acetaminophen were used for analgesia. The number of episodes and the severity of vomiting and retching were recorded for the first 24 hr postoperatively, as was the use of rescue antiemetics. RESULTS: Granisetron 20 micrograms.kg-1 and 40 micrograms.kg-1 were more effective than placebo in reducing the incidence of POV during the first 24 hr (29% in both the granisetron groups vs 84% in the placebo group, P < 0.05). In addition, the number of children experiencing severe vomiting (> or = 3 episodes) was reduced in the granisetron 20 micrograms.kg-1 and 40 micrograms.kg-1 groups compared with placebo (4%, 8% and 48% respectively, P < 0.05). Patients in the granisetron group were discharged home earlier (105 min vs 124 min, P = 0.04). There was no difference in the incidence of POV between the two granisetron groups. CONCLUSION: Preoperative oral granisetron in a dose of 20 micrograms.kg-1 provided effective prophylaxis against POV in children undergoing stabismus repair.

Acetaminophen↗