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BACKGROUND: The aims of this study were to assess the safety and efficacy of surgeons performing colonoscopy, and to use the results to reevaluate currently available credentialing guidelines. METHODS: A prospective outcomes study was designed to include all members of the Society of American Gastrointestinal Endoscopic Surgeons (SAGES). End points were related to the efficacy and safety of colonoscopy. Credentialing guidelines were reviewed. RESULTS: Between April 1998 and September 1999 13,580 colonoscopies were prospectively entered into a database. The most common indications were rectal bleeding, colonic polyps, and change in bowel habits. The colonoscopy was normal or revealed only diverticulosis or nonspecific inflammation in 8,473 (62.4%), lower gastrointestinal bleeding in 4 (0.03%), polyps in 4,645 (34.2%), and tumors in 458 (3.4%) patients. The most common biopsy methods for polyps or tumors were the snare (n = 1,728; 34%), the hot (n = 1,600; 31%), and the cold (n = 1,340; 22%) procedures. The colonoscopy was complete in 12,495 cases (92%), requiring a mean procedure time of 22.7 min (range, 1-170 min). Intraprocedural complications included arrhythmia (n = 14; 0.1%), bradycardia (n = 115; 0.8%), hypotension (n = 171; 1.2%), and hypoxia (n = 806; 5.6%). Postprocedural complications were seen in 27 patients (0.2%). Bleeding (n = 10; 0.07%) was managed by observation alone (n = 9; 0.06%) and repeat colonoscopy with transfusion (n = 1; 0.01%). Perforation (n = 10; 0.07%) was treated successfully by observation with conservative management (n = 5; 0.05%) and surgery (n = 5; 0.05%); severe abdominal pain (n = 4; 0.03%) was managed by observation and conservative therapy; and bronchospasm (n = 2; 0.015%) was managed by observation and supportive care. One single mortality (0.007%) was that of a 70-year-old man with a massive lower gastrointestinal hemorrhage who had a cardiac arrest in the recovery room following colonoscopy. The complication rate was not significantly associated statistically with either the level of experience or the number of prior or annual colonoscopies. However, prior colonoscopic experience did have an impact on the completion rate (p < 0.001) and was inversely proportional to the time to completion (p < 0.001). Similarly, the number of annual colonoscopies affected the completion rate and was inversely correlated with the time to completion (p < 0.001). CONCLUSIONS: This large prospective outcomes study showed that colonoscopy performed by surgeons can be rapidly and successfully done with acceptably low morbidity and mortality. There was no association between experience and complications. However, a minimum of 50 prior colonoscopies and 100 annual colonoscopies were associated with a significant improvement in the rate of completion. There was also a significant correlation between both prior and ongoing annual experience and the time required for the examination. No minimum number of cases can be mandated for credentialing to perform "safe" colonoscopies.

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To assess the effects of practice and dynamic instruction on changes in speed and accuracy during acquisition of simulated laparoscopic surgical skills.Fourteen PGY-1 general surgery residents were randomly assigned to 1 of 2 experimental conditions (n = 7 per group), either practice only or practice with instruction, and required to perform 10 trials of each of 2 laparoscopic surgical skills-cannulation and object passing. Practice only subjects were given verbal instructions for each task, and corrective feedback only after trial 1. Practice with instruction subjects were treated the same, but also saw a videotaped demonstration and received dynamic feedback during and between each trial. Performance speed was recorded for each trial and number of errors was recorded for trials 8 to 10 by videotape review.Mean speed for subjects in both groups increased significantly for both tasks (p < 0.01). Practice with instruction subjects committed significantly fewer errors on object passing (p < 0.04) and were less variable in the number of errors committed during the cannulation task (p < 0.01).Practice, with or without dynamic instruction, results in significant improvement in the speed of performance of simulated laparoscopic surgical skills. The addition of dynamic instruction to simulator-based practice improves the quality and consistency of resident acquisition of laparoscopic surgical skills.

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Granular cell tumors are rare, invariably benign, and often solitary tumors, which infrequently involve the gastrointestinal tract. We report the unique presentation of a granular cell tumor of the internal anal sphincter in a 75 year-old female. The tumor was detected during investigation of new rectal bleeding and was excised using a transanal approach and sphincter repair. At five-year follow-up the patient reported normal continence to stool and flatus and demonstrated no evidence of tumor recurrence. Immunohistochemical studies cite the Schwann neural cell as the origin of the granular cell tumor. Cytoplasmic features include acidophilic, p-aminosalicylic acid-positive, diastaseresistant granules. Granular cell tumors may be located anywhere in the body, but anorectal involvement is rare. In our own search of the world literature, no other cases were reported specifically to involve the anal sphincter. Granular cell tumors are usually detected incidentally but may be symptomatic, especially when the anorectal region is involved. Symptoms include perianal discomfort and bleeding. Adequate local excision is effective for both diagnosis and treatment of anorectal granular cell tumors. Careful follow-up should be performed after excision because of the risk of recurrence.

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BACKGROUND/AIMS: Jejunal diverticulosis (JD) is a rare disease that has a variable presentation. The signs, symptoms, diagnosis, complications and treatment of JD will be discussed through a review of the literature and a series of cases from our own institution. METHODS: A retrospective analysis of the diagnosis, treatment and complications of JD was performed by a literature review. This was accompanied by a series of four cases of JD diagnosed and treated in our own institution. CONCLUSIONS: JD is a rare disease in which most patients are asymptomatic. However, JD's different complications are serious and can be fatal. The treatment is mainly surgical; however, there have been cases where nonsurgical management was successful.

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BACKGROUND: The capability of the 193-nm excimer laser to ablate the cornea and to remove opacities and various other corneal diseases in a procedure called phototherapeutic keratectomy (PTK) has been demonstrated. In this study we evaluated the long-term results of PTK for treatment of granular and lattice corneal dystrophies. METHODS: Four eyes with granular or lattice corneal dystrophy were treated with a mean follow-up of 47.8 months (range, 36 to 58 months). Focal ablations of the central cornea with an ablation zone of 5.5 to 6.0 mm were performed. Ablation depth was 110 microns in three eyes and 140 microns in one eye. RESULTS: Removal of corneal opacities allowed for improvement in corrected visual acuity in all patients. Mean corneal thickness in the area of pathology decreased from 0.583 mm before surgery to 0.449 mm after surgery. Spherical equivalent of the manifest refraction measurements increased by a mean of +5.09 D. There were no major complications, but all patients developed slight haze. There was a hyperopic shift in three eyes. CONCLUSION: Our long-term results suggest that PTK is a safe and effective alternative to penetrating and lamellar keratoplasty in patients with granular or lattice corneal dystrophies.

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OBJECTIVES: To compare the effect of topical 0.5% ketorolac tromethamine and 0.1% diclofenac sodium on human corneal sensitivity and to assess the intensity of burning sensation at specific intervals after drop instillation. DESIGN AND SETTING: Double-masked parallel clinical study. PATIENTS: Eleven women and 4 men (8 white, 4 Hispanic, 3 Asian), 22 to 60 years of age (mean [ +/- SD], 34 +/- 10 years). INTERVENTIONS: Repeated instillation of either ketorolac and placebo or diclofenac and placebo at 5-minute intervals. MAIN OUTCOME MEASURES: Assessment of corneal sensitivity before instillation, immediately after instillation, and after termination of drop application; and subjective evaluation of burning sensation by asking participants to rate burning on a scale ranging from 0 (none) to 3 (severe) after each drop application. RESULTS: Both diclofenac (P < .01) and ketorolac (P < .01) decreased corneal sensitivity significantly, while the placebo had no measurable effect. After administration of additional drops over time, the effect of diclofenac and ketorolac increased. After termination of the drug instillation, corneal sensitivity returned to baseline significantly slower (P < .01) in participants receiving diclofenac than in those receiving ketorolac. Ketorolac (P = .01) and diclofenac (P < .05) were significantly more effective in whites than in nonwhites. Mean burning sensation was mild, and there was no statistically significant difference between the 2 drugs on this measure (P = .12). CONCLUSIONS: The decrease in corneal sensitivity in normal human corneas is more pronounced and longer lasting with diclofenac than with ketorolac. Both drugs are well tolerated topically and may be useful for pain reduction after refractive corneal surgery.

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BACKGROUND: To develop an in vitro model to study the effects of excimer laser keratectomy on corneal stromal cells, we evaluated two types of collagen gel populated with keratocytes. METHODS: Keratocyte-populated collagen gels were prepared with type I collagen in 6-well plates or in culture plate inserts, the bottom of which consisted of a nitrocellulose membrane, contained within 6-well plates. The gels were ablated by the 193-nm excimer laser, set to ablate 50, 100, or 200 microns deep, and was observed under a phase-contrast microscope for 2 days. RESULTS: Keratocytes cultured in collagen gel developed cytoplasmic processes and formed networks of interconnected cells. Cells within the ablated area in the 6-well plates began to lose their cytoplasmic processes and became round approximately 3 hours after excimer laser ablation. These cellular changes were more prominent in the gels ablated to a depth of 200 microns. Cells outside of the ablation zones in the 6-well plates and the culture plate inserts remained intact. CONCLUSIONS: These results suggest the use of keratocyte-populated collagen gel as an in vitro model of cellular response to excimer laser keratectomy and also suggest that gel prepared in culture plate inserts is the preferred method.

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We tested the effect of topical diclofenac sodium on corneal sensitivity in the human eye. Corneal sensitivity was measured in ten adult subjects with the Cochet-Bonnet esthesiometer before, and immediately after, applying one drop of diclofenac sodium 0.1% in one eye and one drop of diclofenac vehicle in the other eye. Application was repeated every five minutes for 20 minutes; then no more drops were applied, and corneal sensitivity was measured every 15 minutes until sensitivity measurements returned to baseline levels. Diclofenac sodium decreased corneal sensitivity significantly (P = .0001) in all ten subjects, compared with eyes treated with the vehicle. The effect of diclofenac sodium increased as additional drops were administered. After the drug instillation was stopped, corneal sensitivity returned to baseline measurements within less than an hour in all the subjects. Diclofenac sodium substantially lowers sensitivity in normal, unoperated-on human corneas; the vehicle has no measurable effect on sensitivity.

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We performed phototherapeutic keratectomy with a 193-nm excimer laser on 18 sighted patients (18 eyes) to treat corneal opacities. The corneal opacities were caused by corneal dystrophies in five patients; corneal scars secondary to corneal ulcers in six patients; corneal scar secondary to trauma in four patients; and band keratopathy, atopy, or corneal calcification in three patients. Mean follow-up was eight months (range, two to 18 months). Corneal clarity improved in 14 of the 18 eyes (77.7%). Four patients, three with band keratopathy or calcification and one with postinfectious corneal scar, did not improve. Uncorrected visual acuity improved in 11 patients, did not improve in five patients (including the four patients in whom treatment failed), and decreased in another two patients, apparently because of an increase in irregular astigmatism. A hyperopic shift was observed in ten patients. None of the successfully treated eyes developed surface problems or recurrence of the disease during the follow-up. Phototherapeutic keratectomy thus appears to be a safe and effective alternative to penetrating keratoplasty in some patients with selected anterior stromal opacities.

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Nine eyes underwent superficial ablation with excimer laser for treatment of compound myopic astigmatism. In eight of the eyes, corneal cylinder was naturally-occurring, and in one eye the astigmatism had developed following retinal detachment surgery. All patients have been followed for 9 months. The pre- and postoperative cylinder was -2.7 +/- 0.4 diopters and -1.3 +/- 0.4 diopters, respectively, while the pre- and postoperative spherical equivalent was -4.7 +/- 0.4 diopters and -1.3 +/- 0.4 diopters, respectively. Uncorrected acuity improved from a preoperative mean of 20/300 to a postoperative mean of 20/40. Patients with a residual refractive error often demonstrated reasonably good unaided acuity. Toric ablations with the excimer laser can be performed at the same time as ablations for myopia, and appear to represent a promising strategy for correction of compound myopic astigmatism; the relative safety and efficacy of this procedure, and of combined radial and astigmatic keratotomy remain to be determined.

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We performed cylindric corneal ablations with the excimer laser on 12 patients to correct severe, disabling astigmatism after keratoplasty. In some patients, an additional ablation was performed to correct myopia. Patients were followed up for an average of eight months (range, six to 14 months). Uncorrected visual acuity improved in nine patients, and nine of the 12 patients had a decrease in refractive cylinder at last follow-up. The mean preoperative refractive cylinder was 7.0 +/- 3.6 diopters, which decreased to a mean of 3.1 +/- 2.6 diopters at one month (P = .0003) and 4.3 +/- 2.9 diopters at last follow-up (P = .03). Keratometric astigmatism decreased from 7.5 +/- 3.9 diopters preoperatively to 5.2 +/- 3.9 diopters at the last follow-up (P = .001). Mean spherical equivalent was reduced from -7.4 +/- 4.2 diopters preoperatively to -3.3 +/- 4.4 diopters postoperatively (P = .003). Postoperative corneal haze, when present, did not reduce visual acuity. Excimer laser superficial keratectomy thus appears to be safe when used for postkeratoplasty ametropia, although substantial regression may limit its effectiveness in some patients.

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BACKGROUND: Photorefractive keratectomy for myopia can be performed using an expanding or contracting iris diaphragm, either of which allows for greater ablation centrally and less tissue ablation toward the edge of the treatment zone. METHODS: To compare the effects of these two strategies, eight rabbits underwent bilateral 5.00-diopter myopic ablations, performed with a contracting diaphragm in one eye and an expanding diaphragm in the other. RESULTS: The rate of epithelial healing and degree of anterior stromal haze, monitored by a masked observer, were similar for the two groups, as was the amount of corneal flattening. CONCLUSIONS: These results in rabbit corneas do not suggest a particular advantage of either the expanding or contracting apertures for achieving central corneal flattening in photorefractive keratectomy.

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Radial keratotomy flattens the cornea, but in a nonuniform fashion. We used computer-assisted topographic analysis to examine curvature changes in different regions of the cornea. Within 45 days after surgery in human eyes, the central and midperipheral cornea flattens and the periphery steepens. Shortly after surgery, the central cornea (within 1-1.5 mm of the corneal light reflex) is steeper than the adjacent midperipheral cornea (1.5-3 mm peripheral to the light reflex). With time, however, the central cornea flattens more than the midperiphery, such that it is no longer relatively steeper. This regional variability in corneal curvature after radial keratotomy helps explain phenomena such as multifocal lens effect after radial keratotomy, and the changes with time account for the conflicting results observed clinically in human corneas and experimentally in human eye bank eyes.

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Corneal anesthesia or hypesthesia can complicate refractive surgical procedures such as epikeratophakia and radial keratotomy. An esthesiometer was used to measure the corneal sensitivity in unoperated-on corneas and fellow corneas after excimer laser photorefractive keratectomy. Decrease in corneal sensitivity was noted within six postoperative weeks, with mean sensitivity being 75.2% +/- 13.3% of normal. Within the first three postoperative months, the patients operated on for correction of compound astigmatism recovered 95.7% +/- 5.3% of the corneal sensitivity, whereas the patients operated on for correction of severe myopia recovered 86.2% +/- 11.2% (P = .07). None of the patients had delayed epithelial healing or recurrent corneal erosions during the time of decreased corneal sensitivity. In otherwise normal myopic eyes, photorefractive keratectomy measurably reduced corneal sensitivity for several postoperative weeks.

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A 46-year-old man underwent phototherapeutic keratectomy with a 193-nm excimer laser in an attempt to remove a superficial corneal scar that had been present for 36 years. The scar proved to be resistant to ablation with the laser, while relatively normal stroma was easily ablated. Histopathologic examination of the corneal button removed 3 months after excimer laser surgery revealed absence of Bowman's membrane in the area of ablation, superficial stromal disorganization and scarring, raised nodules of collagenous tissue extending into the epithelium, and no calcification within the lesion. Ultrastructural examination was remarkable for irregularly oriented collagen fibers within the scar. The resistance of this lesion to excimer laser ablation appears to have been the consequence of marked differences in rates of ablation between normal stroma and the very long-standing scar.

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Excimer laser photorefractive keratectomy can flatten the central cornea, thereby eliminating myopic refractive errors; in older patients, however, presbyopia limits satisfaction. Computer-assisted topographic analysis of corneas after refractive surgery indicates that a minority of patients achieve a multifocal lens effect, such that they maintain reasonable acuity over a range of defocus. We have purposefully attempted to create a multifocal refractive effect and have analyzed the subsequent topographies quantitatively to determine if multifocality was achieved. In corneas not operated on and plastic hemispheres, a fairly small range of corneal powers is observed; the range of powers is increased after a monofocal ablation. After multifocal ablations, a greater spread of surface powers is observed, often with a bimodal distribution, indicative of an apparent multifocal effect. These observations suggest that in some patients undergoing photorefractive keratectomy for myopia, it may be possible to reduce symptoms of presbyopia, although a decrease in image contrast or monocular diplopia may complicate this approach.

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PURPOSE: To examine the effects of blowing nitrogen gas over the cornea during photorefractive keratectomy. METHODS: Excimer laser ablations for myopia were performed on rabbit corneas with or without the blowing of nitrogen across the surface of the cornea. All eyes underwent a 5-diopter myopic ablation; in 8 eyes, a ring was used to blow nitrogen gas across the cornea, and, in 8 eyes, the same ring was used, but no nitrogen gas was blown. RESULTS: Epithelial healing occurred more rapidly in the eyes that were not treated with the gas (3.8 +/- 1.3 days) than in the gas-treated group (6.1 +/- 0.8 days; P = 0.0025). Corneal haze was greater in the group treated with gas. Results of histologic examination showed the ablated area to have a smoother surface when nitrogen was not blown across the cornea surface. CONCLUSION: Superficial corneal deturgescence produced by the nitrogen gas appears to result in a rougher surface immediately postoperatively with undesirable effects on surface healing, but further studies will be necessary to determine the applicability of these results to humans.

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A computerized videokeratography system was used to evaluate diurnal changes in corneal curvature of both untreated and surgically treated eyes of 11 patients who had undergone unilateral radial keratotomy. The mean postoperative interval was 34.5 months. Both corneas operated on and those not operated on steepened on average from morning to evening. For untreated eyes, this diurnal steepening was statistically significant at a distance of 0.5 mm from the corneal apex (mean +/- SE, 0.36 +/- 0.07 diopter) and in the inferotemporal quadrant (0.28 +/- 0.08 D); in eyes that had undergone radial keratotomy, steepening was significant at from 1.0 to 3.0 mm from the corneal apex (0.39 +/- 0.07 D) and temporal, inferotemporal, inferior, inferonasal, nasal, and superonasal to the corneal apex (0.42 +/- 0.08 D). The greatest steepening in the eyes treated with radial keratotomy compared with the untreated eyes occurred at 1.5 to 2.5 mm peripheral to the corneal apex in the inferonasal and nasal octants. Diurnal changes in intraocular pressure, corneal thickness, number of incisions, clear-zone size, postoperative period, and patient sex were not predictive of the magnitude of morning-to-evening change. Furthermore, diurnal changes in corneal curvature of untreated eyes were not predictive of diurnal changes in the fellow eyes after radial keratotomy.

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Quantitative analysis of the central corneal refractive powers of both eyes of three patients demonstrated that, after radial keratotomy, the corneas tended to have a greater range of refractive powers than preoperatively, and that the corneas with a multifocal effect had a wider distribution of refractive powers than the corneas of eyes without this effect. It may be possible to intentionally achieve a multifocal lens effect by designing a refractive procedure to predictably widen the distribution of central corneal refractive powers.

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