Inadvertent inhalation anaesthesia during surgery under retrobulbar eye block.
I describe a case of inadvertent inhalation anaesthesia during surgery under retrobulbar anaesthesia and its management. Some of the hazards of supplementary oxygen delivery during monitored anaesthetic care and the actions taken to prevent this mishap recurring are discussed. (+info)
The effect of propranolol versus placebo on resident surgical performance.
PURPOSE: To determine whether propranolol can decrease surgical tremor and anxiety in residents performing ocular microsurgery without impairing patient or physician safety. METHODS: In this randomized, double-masked, crossover study, 5 third-year ophthalmology residents ingested a capsule containing either propranolol, 40 mg, or placebo 1 hour prior to performing ophthalmic microsurgery. All residents were healthy men under age 30 years. Prior to commencement of the study, all participants had successfully been administered a test dose of propranolol without side effects. The study took place over a 10-week period. At the conclusion of each case, both the resident and attending surgeon observer independently completed a form grading, on a sliding scale: (1) amount of overall tremor; (2) amount of tremor during placement of the first 3 sutures after lens or nucleus extraction; (3) anticipated difficulty of the case; (4) actual difficulty with the case; and (5) anxiety (surgeon only). In addition, the type of procedure performed, complications encountered, and surgeon side effects were recorded. The data were analyzed with a 2-way analysis of variance for unbalanced data. RESULTS: A total of 73 surgical cases were performed; the surgeons were administered propranolol for 40 cases and placebo for 33. As judged by the resident surgeon, there was a highly significant effect of propranolol in decreasing anxiety (P = .0058), reducing surgical tremor overall (P < .0001), and reducing tremor while placing the first 3 sutures following lens extraction (P < .0001). There was no treatment-by-surgeon interaction for any of the measures. Complications and difficulty of the case, as judged by both the resident and attending surgeons, were not significantly different in the propranolol versus placebo groups (P > .05). There were no side effects reported or observed in any of the surgeons. CONCLUSIONS: Propranolol, 40 mg, administered 1 hour prior to surgery, significantly decreases tremor and anxiety in the surgeon without untoward effects to the surgeon and the patient. However, it is unknown whether decreased tremor and anxiety improved surgical outcome. (+info)
Trends in vitreoretinal surgery at a tertiary referral centre: 1987 to 1996.
AIM: To identify trends in vitreoretinal surgery at a tertiary referral centre from 1987 to 1996. METHODS: A retrospective study of patients who had undergone vitreoretinal surgery at St Paul's Eye Unit over two 6 month periods in 1987 and 1996. Preoperative ocular status, surgery details, and outcome were collected. chi 2 and Mann-Whitney U tests were used to analyse the data. RESULTS: The two periods under study were July to December 1987 and January to June 1996. 110 operations performed during 1987 (96 patients) and 330 operations during 1996 (289 patients) were analysed. There was a fourfold rise in the number of tertiary referrals and a seven-fold rise in the number of operations performed for conditions other than rhegmatogenous retinal detachment (RRD). Increasing indications for surgery included diabetic eye disease, macular hole, dropped nucleus, endophthalmitis, and subretinal neovascular membrane. There was a rise in the proportion of patients with RRD following cataract surgery (from 19.5% to 29.5%). For both primary repair and reoperation, vitrectomy with internal tamponade was more commonly used in 1996. The anatomical success rate for primary repair changed from 76.6% to 84.7% after one operation and from 89.1% to 94.3% following additional surgery. CONCLUSIONS: This study points to a trend towards subspecialisation and tertiary referral in vitreoretinal surgery. Vitrectomy techniques are more commonly used for the primary repair of RRD and are applied to a wider spectrum of diseases. (+info)
Erbium: YAG laser ablation of retinal tissue under perfluorodecaline: determination of laser-tissue interaction in pig eyes.
PURPOSE: To evaluate the effect of Er;YAG laser on pig retina using a perfluorodecaline/retina interphase with the goal of precisely determining the extent of retinal tissue ablation. METHODS: Free running (tau = 250 microsec) Er:YAG laser pulses were transmitted through a zirconium fluoride (ZrF4) fiber guarded by quartz rod (d = 1000 microm). Laser pulses were applied to the retinal surface of enucleated pig eyes. Eyes were mounted in a specially designed rotating sample holder. The fiber probe was elevated 1.0 +/- 0.3 mm above the retinal surface with perfluorodecaline serving as transmitting medium. The laser energy was applied in a circular pattern with a radius of 3.0 mm. Radiant exposures were set to 1, 3, 5, and 10 J/cm2. RESULTS: Tissue ablation linearly increased with radiant exposure from 3.2 +/- 3.7 microm at 1 J/cm2 up to 40.9 +/- 12.9 microm at 10 J/cm2. Thermal tissue changes extended 70 +/- 10 microm vertically into the retina and 25 +/- 5 microm horizontally. Distortion of outer photoreceptor segments was noticed when the retina was exposed to radiant exposures of 3 J/cm2 or higher. CONCLUSIONS: The Er:YAG laser in combination with perfluorodecaline produced precise ablation of the pig retina, which suggests the feasibility of this technique for safe ablation of epiretinal membranes. (+info)
Combined nevi of the conjunctiva.
PURPOSE: To report the clinical and histologic features of combined nevi of the conjunctiva, a type of nevus that is not uncommon in the skin but has rarely been reported in the conjunctiva. METHODS: Conjunctival nevi and melanomas from the files of the University of California, San Francisco, eye pathology laboratory were reviewed from 1984 to 1999 for the presence of features of both standard nevocytic nevi and blue nevi. Clinical histories and, when available, clinical photographs were obtained. RESULTS: Thirty-one combined nevi were discovered during the 15-year period between 1984 and 1999. One case before 1984 had been incorrectly diagnosed as a junctional nevus. The dendritic and spindle-shaped blue nevus cells had been overlooked because they were not recognized as distinct from the standard nevocytic nevus cells. The recognition of a blue as well as a brown color, a deep as well as a superficial component in the lesion, or a history of pigmentation since birth may help to establish the correct clinical diagnosis and prevent an unnecessarily deep surgical resection. Although growth of the lesion or "satellites" in some patients may favor a clinical diagnosis of melanoma, none of the lesions in this series were malignant. CONCLUSION: Despite a paucity of reports of combined nevi of the conjunctiva in the medical literature, this type of nevus--a combination of a nevocytic and a blue nevus--is common and has been overlooked in the past. (+info)
Achieving success with the silicone expander for overacting superior obliques.
PURPOSE: To report the results of and complications with silicone expander surgery for the overacting superior oblique. METHODS: A total of 26 patients with bilateral overaction of the superior oblique and A-pattern strabismus and 5 patients with unilateral overacting superior oblique secondary to inferior oblique palsy were treated with a 7 mm silicone expander. Care was taken not to enter the sub-Tenon's space. RESULTS: The group that underwent bilateral superior oblique surgery had an average preoperative pattern of 37.42 diopters (D) and an average correction of 35.37 D. Three patients had a severe unilateral postoperative inflammatory incident that was successfully treated with oral and topical corticosteroids. One of these patient developed Brown's syndrome. Another patient, who had no postoperative inflammatory incident, also developed Brown's syndrome. In these 4 patients, the sub-Tenon's space was inadvertently entered during surgery. CONCLUSION: The silicone expander surgery has a very high success rate in treating the A-pattern associated with the bilateral overacting superior oblique. This procedure also works well for the unilateral superior oblique that overacts owing to an inferior oblique palsy. No cyclotorsion symptoms occurred after this surgery. However, 4 patients had complications because the sub-Tenon's space was exposed during surgery. With this procedure, there is a learning curve to obtain the skill not to enter the sub-Tenon's space. (+info)
Scar remodeling after strabismus surgery.
PURPOSE: Patients with overcorrected strabismus (and several patients with undercorrection after extraocular muscle resection) underwent exploration of previously operated muscles, with the intention of advancing their tendons to prevent the need for surgery on additional muscles. Unexpectedly, it was found that, in many cases, an elongated scar segment of variable length was interposed between the muscle and its insertion site on the sclera. Laboratory investigations were carried out to elucidate the underlying mechanism(s) and to create an animal model of the disorder. METHODS: Lengthened scars were repaired on 198 muscles during 134 procedures performed on 123 patients. The scars consisted of amorphous connective tissue interposed between the globe and normal tendon. Repair was accomplished by excision of the scar and reattachment of the muscle to sclera, using absorbable sutures in 64 cases and nonabsorbable sutures in 70 cases. Histopathologic examination was performed on 82 clinical specimens, and tissue culture studies were performed on 7 specimens. To develop an animal model, 10 New Zealand white rabbits underwent bilateral superior rectus resection. Half of the eyes received sub-Tenon's injections of collagenase over the operative site during weeks 2, 3, 5, and 6 postoperatively; the other half received saline solution injections on the same schedule. At 10 weeks, half the sites were studied histologically, and the other half underwent collagen creep analysis. In a second study, the use of absorbable versus nonabsorbable sutures was compared in the rabbit model. RESULTS: In the clinical cases, the mean length of the elongated scar segments was 4.2 mm. A total of 105 of the 134 repair procedures were judged successful. Thirty-one procedures resulted in recurrence of the original overcorrection; 7 of these had documented restretches. Factors that distinguished patients with stretched scars from patients with classic slipped muscles included minimal or no limitation of versions, less separation of the tendons from sclera, and thicker appearance of the scar segments. The use of nonabsorbable sutures in the repair procedure reduced the recurrence rate. Histologic examination of the clinical stretched scar specimens showed dense connective tissue that was less well organized compared with normal tendon. In the tissue culture studies, cells cultured from the stretched scar specimens grew rapidly and were irregularly shaped. A high-molecular-weight protein was identified in the culture medium. By contrast, cells cultured from normal tendon (controls) grew more slowly and regularly, stopped growing at 4 days, and produced less total protein than cultured stretched scar specimens. In the animal model studies, the collagenase-treated sites showed elongated scars with increased collagen between the muscle and the sclera, as well as increased collagen creep rates, compared with the saline-treated controls. The use of nonabsorbable sutures in collagenase-treated animal model surgery sites was associated with shorter, thicker scars compared with similar sites sutured with absorbable sutures. CONCLUSIONS: A lengthened or stretched, remodeled scar between an operated muscle tendon and sclera is a common occurrence and is a factor contributing to the variability of outcome after strabismus repair, even years later. This abnormality may be revealed by careful exploration of previously operated muscles. Definitive repair requires firm reattachment of tendon to sclera with nonabsorbable suture support. (+info)
Brown's syndrome: diagnosis and management.
PURPOSE: To better understand the various etiologies of Brown's syndrome, define specific clinical characteristics of Brown's syndrome, describe the natural history of Brown's syndrome, and evaluate the longterm outcome of a novel surgical procedure: the silicone tendon expander. Also, to utilize a computer model to simulate the pattern of strabismus seen clinically with Brown's syndrome and manipulate the model to show potential surgical outcomes of the silicone tendon expander. METHODS: Charts were reviewed on patients with the diagnosis of Brown's syndrome seen at a children's hospital ophthalmology clinic from 1982 to 1997, or seen in the author's private practice. Objective fundus torsion was assessed in up gaze, down gaze, and primary position in 7 Brown's syndrome patients and in 4 patients with primary superior oblique overaction. A fax survey was taken of members of the American Association of Ophthalmology and Strabismus (AAPOS) listed in the 1997-1998 directory regarding their results using the silicone tendon expander procedure for the treatment of Brown's syndrome. A computer model of Brown's syndrome was created using the Orbit 1.8 program by simulating a shortened superior oblique tendon or by changing stretch sensitivity to create an inelastic muscle. RESULTS: A total of 96 patients were studied: 85 with Brown's syndrome (38 with congenital and 47 with acquired disease), 6 with masquerade syndromes, 1 with Brown's syndrome operated on elsewhere, and 4 with primary superior oblique overaction in the torsion study. Three original clinical observations were made: 1. Significant limitation of elevation in abduction occurs in 70% of Brown's syndrome cases surgically verified as caused by a tight superior oblique tendon. Contralateral pseudo-inferior oblique overaction is associated with limited elevation in abduction. 2. Traumatic Brown's syndrome cases have larger hypotropias than nontraumatic cases (P < .001). There was no significant hypotropia in primary position in 56 (76%) of 74 congenital and nontraumatic acquired cases despite severe limitation of elevation. 3. Of 7 patients with Brown's syndrome, 6 had no significant fundus torsion in primary position, but had significant (+2 to +3) intorsion in up gaze. Spontaneous resolution occurred in approximately 16% of acquired nontraumatic Brown's syndrome patients. The silicone tendon expander was used on 15 patients, 13 (87%) were corrected with 1 surgery and 14 (93%) with 2 surgeries. The only failure was a Brown's syndrome not caused by superior oblique pathology. Five of the silicone tendon expander patients had at least 5 years follow-up (range, 5 to 11 years). Four (80%) of the 5 patients had an excellent outcome with 1 surgery, final results graded between 9 and 10 (on a scale of 1-10, 10 is best). The fifth patient had a consecutive superior oblique paresis and a good outcome after a recession of the ipsilateral inferior oblique muscle. The AAPOS survey had a mean outcome score of 7.3, with 65% between 8 and 10. There were 9 (6%) complications reported: 4 related to scarring and 5 extrusions of the implant. Three of the 5 extrusions were reported from the same surgeon. The computer model of an inelastic superior oblique muscle-tendon complex best simulated the motility pattern of Brown's syndrome with severe limitation of elevation in adduction, mild limitation of elevation in abduction, minimal hypotropia in primary position, no superior oblique overaction, and intorsion in up gaze. CONCLUSIONS: The presence of mild to moderate limitation of elevation in abduction is common, and its presence does not eliminate the diagnosis of Brown's syndrome. The majority of Brown's syndrome patients have a pattern of strabismus consistent with an inelastic superior oblique muscle-tendon complex that does not extend, but can contract normally; not the presence of a short tendon. The presence of inelastic or tethered superior oblique muscle-tendon can be diagnosed without forced duction testing by observing the pattern of strabismus including torsion. Because of the chance for spontaneous resolution, conservative management, not surgery, should be the first line of treatment for acquired Brown's syndrome. If surgery is indicated, a novel procedure, the silicone tendon expander, is an effective option with excellent long-term outcomes. (+info)