Fat adherence syndrome treated with intraoperative mitomycin-C: a rabbit model

The effect of platelet-rich fibrin on wound healing following strabismus surgery

PURPOSE

To investigate the effect of platelet-rich fibrin (PRF) on post-operative wound healing following strabismus surgery in a rabbit model.

METHODS

Nine New Zealand white rabbits were involved in the study. One of these nine rabbits was kept in control without having any operation. Both eyes of eight rabbits underwent superior rectus muscle (SRM) resection. After resection of SRM, PRF was applied to SRM of the right eyes. In the left eye, SRM was not wrapped with PRF and served as a control. The rabbits were sacrificed and enucleated 6 weeks after the surgery. Inflammation and vascular proliferation were assessed by staining with haematoxylin-eosin. Scar and fibrosis were examined by the Masson trichrome staining. Immunohistochemical staining was performed for a vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (α-SMA).

RESULTS

There was no significant difference in terms of inflammation (p = 0.535), vascularization (p = 0.602), and fibrosis (p = 0.745) between the eyes. Immunohistochemical staining for VEGF demonstrated no significant difference (p = 0.745). However, significant staining for α-SMA was detected in PRF-treated eyes compared with control eyes (p = 0.037).

CONCLUSION

Consistent with the hypothesis that PRF facilitates wound healing as a biocatalyst, there was only a significant difference for α-SMA related to myofibroblast activity which is important for wound remodelling. Future comprehensive studies are needed to extend these results.

Comparison of the Effectiveness of Mitomycin-C and Viscoat on Delayed Adjustable Strabismus Surgery in Rabbits

Purpose

To determine a way to prevent the formation of adhesions and delay the time of suture adjustment in the course of adjustable strabismus surgery, an animal study was performed to assess and compare the effects of mitomycin C (Mit-C) and viscoelastic material Viscoat (sodium hyaluronate 3% and chondroitin sulphate 4%, Alcon, Fort Worth, TX).

Methods

Right eyes of 47 rabbits were divided into three groups. After recession of the superior rectus muscle (SRM), Mit-C was administered beneath and over the SRM in Group M (16 eyes), Viscoat was administered beneath and over SRM in Group V (16 eyes), and ringer lactate was administered in Group C (15 eyes). SRM then recessed 5 mm with adjustable strabismus surgery technique. Animals in each group were subdivided into 1 and 2, where 1 = adjustment 1 week postoperatively and 2 = adjustment 3 weeks postoperatively. Delayed adjustment was performed in M1 group (6 eyes), V1 group (6 eyes), and C1 group (7 eyes) after 1 week; in M2 group (6 eyes), V2 group (6 eyes), and C2 group (6 eyes) after 3 weeks. Histopathologic examinations were performed for the remaining 10 eyes without suture adjustment at the end of first and third weeks after adjustable strabismus surgery. The possible length and the necessary force to adjust and the degree of adhesions were recorded.

Results

When length and strength of the adjustment, adhesions between muscle and sclera, and adhesions between muscle and conjunctiva were taken into consideration, there was no statistically significant difference among M, V, and C groups at postoperative weeks 1 and 3. The force needed for adjustment in M1 group was statistically lower than M2 group.

Conclusions

The intraoperative use of Mit-C (0.4 mg/mL) may decrease adhesion formation in the early postoperative period, especially in the first week. The intraoperative use of Viscoat was not effective in reducing postoperative adhesions and delaying adjustment.

Fat adherence syndrome following inferior oblique surgery: Treatment and outcomes

PURPOSE

Describe surgical treatment and results in a group of patients diagnosed and operated on of fat adherence syndrome following inferior oblique surgery.

PATIENTS, MATERIAL AND METHODS

Retrospective study of 6 cases diagnosed and treated of fat adherence syndrome following inferior oblique surgery. Mean age was 24.67 years (range, 5-41), 3 males, 5 unilateral and 1 bilateral. Mean vertical deviation was 16.16pd (range, 4-25). Esotropia was associated in 4 cases, diplopia in other 2, and anomalous head posture in 3. A good outcome was considered when the final deviation was less than 10pd, with mild limitation of elevation, without anomalous head posture, and a negative duction forced test.

RESULTS

The final vertical deviation was 6.83pd (range, 0-14). A 2-4mm inferior rectus recession was performed on 4 patients associated to an inferior oblique surgery/exploration. All patients were operated on once, except 1 case. A good outcome was achieved in 3 patients. Anomalous head posture was resolved in 2 of 3 cases. Diplopia resolved after surgery. Only one case achieved orthophoria. Mean evolution time was 34.83 months (range, 6-78).

CONCLUSION

In the treatment of the fat adherence syndrome, an inferior rectus recession is recommended, associated to inferior oblique exploration or surgery. A good favorable outcome was only achieved in half of the cases with surgical treatment. Limitation of elevation could not be completely resolved in any of the patients.

Effective treatment for prevention of post-operative adhesion after strabismus surgery in experimental rabbit model: 0.5 % tranilast ophthalmic solution

Background

Postoperative adhesion is one of the major complications of strabismus surgery and result in motility dysfunction that brings unpredictable surgical outcomes. However, there was no definitely accepted treatment method to prevent postoperative adhesion.

Methods

A prospective, randomized, controlled experimental animal study was performed. Both eyes of each of 14 New Zealand White rabbits underwent superior rectus muscle recession. After the surgical procedure, the subjects were divided randomly into two groups; 0.5 % tranilast ophthalmic solutions and fluoroquinolone antibiotic eye drops were administered to the group tranilast (N = 14), while the group control (N = 14) received fluoroquinolone eye drops only. Five weeks after surgery, we evaluated gross adhesions with a numeric score (0 to 4). In addition, histopathologic examination with hematoxylin & eosin staining, Masson’s-trichrome staining, and anti-transforming growth factor beta 1 (TGF-β1) immuno-histochemical staining were done.

Results

The group tranilast showed significantly less gross adhesion and inflammation than the group control (P = 0.01 and P < 0.001, respectively). Masson’s-trichrome staining revealed that post-operative collagen deposition was more prominent in the group control than the group tranilast (P < 0.001). Moreover, remarkable TGF-β1 expression was observed in areas with excessive collagen deposition.

Conclusions

Instillation of 0.5 % tranilast ophthalmic solution is a simple and effective method for preventing post-operative adhesion after strabismus surgery.

Amniotic membrane for reducing the formation of adhesions in strabismus surgery: experimental study in rabbits

PURPOSE

To evaluate the effect of amniotic membrane in reducing inflammation, fibrosis, adhesion formation, and ocular motility restrictions following strabismus surgery.

METHODS

In the first stage of this prospective, randomized study, 17 rabbits underwent superior rectus muscle recession in both eyes. Surgery was performed in the same manner, but human amniotic membrane was placed over the muscle without sutures in the right eye after recession. After 15 days, the rabbits were killed and their orbits were exenterated and evaluated histopathologically to quantify tissue inflammation and fibrosis. In the second stage, 5 rabbits underwent the same procedure but were killed after 30 days. A dynamometer was used to measure the force required to displace all eyes.

RESULTS

At 15 days postoperatively, eyes with amniotic membrane exhibited an increased inflammatory response and less fibrosis than eyes without amniotic membrane. At 30 days postoperatively, eyes with amniotic membrane continued to exhibit increased inflammation and less fibrosis than eyes without amniotic membrane. In the dynamometer test, more force was needed to displace eyes without amniotic membrane after 15 days, but there was no significant difference between the forces required at 30 days.

CONCLUSIONS

Human amniotic membrane in rabbits led to an increase in the inflammatory process and a decrease in fibrosis formation following strabismus surgery.

Effect of cryopreserved amniotic membrane on the development of adhesions and fibrosis after extraocular muscle surgery in rabbits

PURPOSE

To histopathologically evaluate the effect of cryopreserved human amniotic membrane (AM) transplant on preventing the development of postoperative adhesions after extraocular muscle surgery.

METHODS

Ten albino rabbits were used. The superior rectus muscles were bilaterally resected. In right eyes, the muscle was wrapped with cryopreserved human AM (group AM). In left eyes, the muscle was not wrapped with AM and served as a control group (group C). The rabbits were killed, and the eyes were enucleated 6 weeks after surgery to perform histopathological examination.

RESULTS

On histopathological examination, the AM was present in eight eyes, surrounded by periamniotic inflammation, with no adhesions detected between rectus muscle and sclera, conjunctiva and Tenon's capsule in the segment where the AM was present, but detected elsewhere. Adhesions were detected in the other two eyes of group AM, in which the AM was absent, and in all group C eyes. When comparing eye pairs of each rabbit, AM eyes showed significantly less adhesions between the muscle and sclera (p = 0.009) and between the muscle and Tenon's capsule and conjunctiva (p = 0.008), in the region of AM application, and significantly more foreign body inflammation (p = 0.031), than C eyes. The differences between AM and C eye pairs, in terms of conjunctival inflammation and vascularity and muscle fibrosis, were insignificant (p > 0.05).

CONCLUSIONS

Cryopreserved AM is effective in reducing postoperative extraocular muscle adhesions. Its application is, therefore, recommended during strabismus reoperations.

Short-term response of mitomycin C on the human rectus muscle following strabismus surgery: histological, ultrastructural, and biomechanical evaluation

This study investigated the inflammatory effect of intraoperative mitomycin C (MMC) on adhesion reformation in human rectus muscles. Ten consecutive patients who underwent medial rectus resection had their postoperative rectus muscles divided into two groups: control group (n = 10) and MMC group (n = 10). In the MMC group, the muscle was soaked for 2 min with MMC, prepared as a 0.2 mg/mL (0.02%) solution. The 0.02% MMC reactions were examined using histological analysis with hematoxylin-eosin (inflammatory response) and Masson's trichrome (collagen fibrils), immunoreactivities of cyclooxygenase-II (inflammatory response), and collagen type I and III, scanning electron microscopy analysis to quantify the diameter and D-periodicity of collagen fibrils, and atomic force microscopy analysis to quantify the diameter, D-periodicity, and adhesion force of collagen fibrils. The rectus muscles treated with 0.02% MMC showed a significantly increased inflammatory response (p < 0.05), increased collagen density (p < 0.0001), increased fibril diameter (p < 0.001 or p < 0.05), and decreased fibril adhesion force (p < 0.005) compared to the rectus muscles in the control group. MMC simultaneously caused an inflammatory response as well as nanostructural and biomechanical property changes in the collagen fibril network.

Amniotic membrane in the management of strabismus reoperations

PURPOSE

To reduce postoperative scar formation and to improve duction using amniotic membrane (AM) in strabismus reoperations.

METHODS

A prospective study of interventional case series comprised of 14 patients with restrictive strabismus. Objective clinical findings (visual acuity, angle of deviations and degree of duction deficits) were recorded in both the pre- and post-operative periods. Strabismus surgery included the excision of adhesions and scar tissue, repositioning of extraocular muscles (according to the degree of deviations) and placement of two sheets, one between muscle and tenon and the other between muscle and sclera. Conjunctival recession with covering of the bare sclera using AM was also performed.

RESULTS

The mean preoperative deviation of the patients was 34.3 prism diopters (PD) and mean post-operative deviation was 4.6 PD. The mean pre-operative duction deficit of the patients was 1.7; mean post-operative duction deficit was 0.2. Postoperatively all patients improved in relation to deviation and duction. Less than 8 PD deviations with no duction deficits were achieved in 12 (86 %) of the patients.

CONCLUSIONS

Amniotic membrane placement around the extraocular muscle improves the duction and decreases the residual angle of deviations by inhibiting postoperative scar formation.

Effect of lyophilized amniotic membrane on the development of adhesions and fibrosis after extraocular muscle surgery in rabbits

PURPOSE

To histopathologically evaluate the influence of lyophilized human amniotic membrane transplant on the development of postoperative adhesions and fibrosis after extraocular muscle surgery.

METHODS

Ten albino rabbits were used. The superior rectus muscle was resected 4 mm in both eyes. In right eyes, the superior rectus muscle was wrapped with lyophilized (air-dried, freeze-dried) human amniotic membrane (group AM). In left eyes, the superior rectus muscle was not wrapped with amniotic membrane, and served as a control group (group C). The rabbits were sacrificed and the eyes were enucleated 6 weeks after surgery to perform histopathological examination.

RESULTS

Two rabbits died 1 week after surgery and were excluded. Histopathological evaluation of both eyes of the remaining 8 rabbits was done. The amniotic membrane was not seen in all eyes. On comparing eye pairs of each rabbit, right eyes showed significantly less conjunctival inflammation (p = 0.034), but insignificantly less foreign body inflammation (p = 0.625), adhesions between sclera and muscle (p = 0.206), muscle fibrosis (p = 1.000), and conjunctival hyperemia (p = 0.059) as compared to left eyes.

CONCLUSIONS

Lyophilized amniotic membrane insignificantly reduces postoperative adhesions and fibrosis, when used to wrap the operated upon extraocular muscles, limiting the benefit of this membrane in strabismus surgery.

Effects of solid hyaluronic acid film on postoperative fibrous scar formation after strabismus surgery in animals

PURPOSE

The purpose of this study was to investigate the inhibitory effect of solid hyaluronic acid-carboxymethylcellulose film on the formation of wound adhesion after strabismus surgery on rabbit eyes.

METHODS

The authors performed strabismus surgery on rabbit eyes with hyaluronic acid film applied under and above the muscles. Histological examination was performed 90 days postoperatively using Masson trichrome staining. The length of adhesion tissues in the operated area was quantitatively compared between film-treated and control eyes.

RESULTS

Hyaluronic acid film significantly prevented the formation of adhesions between muscle, conjunctiva, and sclera after strabismus surgery (t test, P < .05).

CONCLUSION

The current results indicate that hyaluronic acid film can inhibit the formation of postoperative adhesion around conjunctiva, muscle, and sclera to some extent. The authors conclude that this substance offers potential benefits for ophthalmic surgery, not only with strabismus surgery but also procedures such as scleral buckle.

Severe fibrosis of extraocular muscles after the use of lyophilized amniotic membrane in strabismus surgery

Various techniques have been used to reduce adhesions after strabismus surgery. Wrapping the extraocular muscles with cryopreserved amniotic membrane has been reported to yield good results. In the case reported here, we used lyophilized amniotic membrane to wrap the extraocular muscles. Extensive adhesions developed, and inelastic, fibrotic muscles were discovered at a subsequent operation.

A procedure to minimize lower lid retraction during large inferior rectus recession in graves ophthalmopathy

PURPOSE

To determine whether complete detachment of the fascia of the capsulopalpebral head during large inferior rectus recession can help to prevent induced lower lid retraction in Graves ophthalmopathy.

DESIGN

Retrospective consecutive case series.

METHODS

Data from patients (39 eyes) with Graves ophthalmopathy undergoing inferior rectus recession were collected retrospectively. Inferior rectus recession was performed by limbus-based incision with adjustable suture. Simultaneous detachment of the fascia of the capsulopalpebral head was achieved by sharp dissection and severing of the fascia. Inferior rectus recession with simultaneous detachment of the fascia of the capsulopalpebral head was performed in 27 eyes and without detachment in 12 eyes. Margin reflex distance (MRD2) was documented preoperatively and 3 months postoperatively.

RESULTS

Of the 39 eyes included in this study, four eyes with preexisting lower lid retraction in the detachment group improved after surgery. Eighteen eyes in the detachment group exhibited the same MRD2 values, and only five eyes showed increased MRD2 values. In contrast, all but one of the 12 eyes in the nondetachment group showed increased MRD2 values. The average change in the MRD2 value 3 months after surgery was 0.04+/-0.59 mm in the detachment group and 1.58+/-0.73 mm in the nondetachment group. There was a statistically significant difference between the two groups (P<.01).

CONCLUSIONS

Simultaneous detachment of the fascia of the capsulopalpebral head during inferior rectus recession can minimize the possibility of lower lid retraction.

Crosslinked hyaluronan hydrogels containing mitomycin C reduce postoperative abdominal adhesions

OBJECTIVE

To evaluate the efficacy of crosslinked hyaluronan (HA) hydrogels that contained covalently-bound mitomycin C (MMC) in reducing postoperative adhesions in a rat uterine horn model.

DESIGN

Two independent parameters were investigated: [1] the quantity of MMC in preformed crosslinked hydrogel films and [2] the efficacy of intraperitoneal injection of in situ crosslinkable solutions.

SETTING

University animal research facility.

ANIMAL(S)

Female Wistar rats.

INTERVENTION(S)

Injuries (3 x 10 mm) were made to contacting serosal surfaces of the medial uterine wall musculature in female rats. Two treatment protocols were used. In the first, sterile crosslinked HA films that contained different MMC loadings (0, 0.5%, and 2%) were applied to two injured uterine horns; control animals received no films. In the second protocol, MMC-loaded crosslinked HA gels that contained different MMC loadings (0.31%, 0.625%, and 1.25%) were spread on the site of uterine horn injury (1 mL); then, an additional 4 mL of the same formulation was injected into the peritoneal cavity after abdominal closure. Control animals were injected with 5 mL of buffer only.

MAIN OUTCOME MEASURE(S)

Extent of postoperative adhesions between uterine horns and with surrounding tissues and organs.

RESULT(S)

Mitomycin C-loaded crosslinked HA films and in situ crosslinked gels were more effective in reducing postoperative adhesion formation than were buffer controls or crosslinked HA films without MMC.

CONCLUSION(S)

Mitomycin C-loaded crosslinked HA films and gels reduced formation of postoperative intraperitoneal adhesions.

Adherence syndrome following inferior oblique surgery: management and outcome of 14 cases

BACKGROUND

Adherence Syndrome is diagnosed by limited upgaze, usually in the presence of an ipsilateral consecutive hypotropia in primary position, which is worse in lateral gaze. There is also a positive forced duction test.

METHODS

A retrospective review of patients diagnosed with sdherence syndrome following strabismus surgery under the care of a single ophthalmologist between 1989 and 2001 was performed. Fourteen patients were identified. All patients were thought to have undergone previous ipsilateral inferior oblique surgery, which was felt to be the cause of the restriction.

RESULTS

We usually performed an extensive conjunctival peritomy over nearly 180 degrees, recessing the conjunctiva while leaving the sclera to re-epithelialise, and in addition recessed the inferior rectus by 2.5-3 mm. Only one patient required an additional operation. Of the 11 patients who had undergone surgery at our institution all showed a significant improvement in their symptoms. five were discharged happy, three continue to be followed and three failed to attend further appointments after their initial visit two weeks post-operation.

CONCLUSIONS

It is not possible to restore normal eye movements in these patients. Our results show that one can improve the appearance in primary position with single vision. Patients should be given realistic expectations before surgery and the limited aims of surgery must be explained.

Use of topical mitomycin C in myoplasty of the medial rectus muscle of rabbits

To possibly reduce postoperative adhesions that occur after ocular myoplasties, we investigated the topical effects of 0.04% mitomycin C on the repaired areas of the medial rectus muscle using an equine renal capsule preserved in 98% glycerin for reinforcement of the sutures. Twenty-four rabbits, divided into two groups of 12 animals each [untreated (control) and treated group (MMC)], were submitted to surgical rupture of the medial rectus muscle of one eye and repair of the defect 24 h later with sutures and an equine renal capsule. Post-operative prophylactic treatment of the two groups consisted of the administration of eye drops containing neomycin, polymyxin B and dexamethasone at regular 6-h intervals for eight consecutive days and daily rinsing with physiological saline. MMC animals received additional treatment with topical 0.04% mitomycin C every 6 h for 14 consecutive days. Slit lamp biomicroscopy showed greater irritation of the ocular surface in MMC animals during the first days post operatively. Adhesions were observed at 15 and 30 days of assessment in the two groups, but were more extensive in control animals at 60 days. Histopathology revealed inflammatory exudation in both groups, which was greater in MMC animals. Mitomycin C (0.04%) instilled at 6-h intervals for 14 consecutive days reduced the occurrence of fibrosis in the myoplastic areas. However, the equine renal capsule was found to be of little benefit for the reinforcement of myoplasties.

Fat adherence syndrome: an animal model

BACKGROUND

Fat adherence syndrome (FAS) is a permanent restrictive strabismus that can occur after periocular surgery or trauma. The pathophysiology is poorly characterized.

METHODS

Under varying conditions, fat autografts were secured with dissolvable sutures between the inferior rectus and the periosteum of the inferior orbital rim in both eyes of 15 New Zealand white rabbits. Sutures without fat autografts were placed in both eyes of three control rabbits. The force required to move the eyeball superiorly 4, 6, or 8 mm was measured with a digital strain gauge preoperatively and 6 weeks after surgery. Twelve of the 15 rabbits with autografts were then sacrificed, and exenteration specimens were taken. The three remaining rabbits (six eyes) were observed for 6 months after placement of fat autografts.

RESULTS

Analysis of variance allowed rejection of the null hypothesis that there was no difference among the postsurgical groups for all deflection points when 6 weeks postoperative was compared to baseline (preoperative) measurements (P < or = 0.05). Regression analyses showed that stiffness at each deflection was dependent on the amount of fat placed in the orbit. In three rabbits observed for 6 months, restriction tended to be stable over the 6-month observation period and was not alleviated by lysis of adhesions or removal of the fat grafts.

CONCLUSION

A fat autograft introduced into an extraocular wound in rabbits will produce a permanent restrictive strabismus. This model may prove useful in the study of FAS.

Upper eyelid retraction after glaucoma filtering surgery and topical application of mitomycin C

PURPOSE

To describe 3 cases of upper eyelid retraction after glaucoma filtering surgery and topical application of mitomycin C and to highlight possible causes.

METHODS

A report of 3 patients, identified over an 8-year interval period, who had development of upper eyelid retraction a few months after undergoing trabeculectomy with mitomycin C in the ipsilateral eye.

RESULTS

Testing for Graves disease, including second-generation thyrotropin receptor antibodies (TRAb), was negative in all cases. A complete physical examination was performed by an internist: Orbital and intracranial neuroimaging studies were ordered when necessary, and all were negative. One patient underwent surgical repair of the eyelid retraction and had a satisfactory result.

CONCLUSIONS

Upper eyelid retraction after filtering surgery is a rarely reported entity. Müller muscle overaction, independent of Graves disease, is a likely cause and has been pointed out as a possible factor in one previous report. Müller muscle fibrosis, euthyroid Graves disease, and mechanical hindrance to an elevated bleb are other possible factors.

Fat adherence syndrome after retinal surgery treated with amniotic membrane transplantation

PURPOSE

We present favorable results with amniotic membrane transplantation in a patient who developed fat adherence syndrome after retinal surgery.

DESIGN

Interventional case report.

METHODS

A 37-year-old man had diplopia resulting from hypotropia of the left eye after retinal detachment surgery. Removal of a previously implanted silicon sponge had little effect because of fibrous adhesion between the inferior rectus muscle and adjacent periorbital fat. We performed amniotic membrane transplantation combined with conventional extraocular muscle surgery.

RESULTS

Postoperatively, supraduction of the left eye became almost full. The field of binocular vision was extended markedly by treatment, both in the primary position and with downward gaze. These improvements remained stable over 1 year of follow-up.

CONCLUSION

Amniotic membrane transplantation appears to be effective for preventing regrowth of restrictive scar tissue in the fat adherence syndrome.

Effectiveness of mitomycin C in reducing reformation of adhesions following surgery for restrictive strabismus

PURPOSE

To evaluate the efficacy of mitomycin C in reducing reformation of adhesions following surgery for restrictive strabismus.

METHODS

Sixteen patients with restrictive strabismus resulting from trauma, retinal detachment surgery, and multiple squint surgeries were randomized to either a mitomycin group (8 patients) or a control group (8 patients). Mitomycin C (0.2 mg/mL) was applied intraoperatively for 5 minutes after release of adhesions. Range of passive ductions was scored for comparison. Postoperative follow-up ranged from 3-18 months.

RESULTS

Compared to controls, the mitomycin C group had better range of passive ductions. There were no complications related to the cornea, intraocular pressure, uveitis, or muscle disinsertion in the mitomycin C group.

CONCLUSION

Intraoperative application of mitomycin C (0.2 mg/mL for 5 minutes) is a safe and effective adjunct to surgery in the treatment of restrictive strabismus.

An experimental study evaluating the effect of Mitomycin C on the prevention of postoperative intraabdominal adhesions

BACKGROUND

Fibroblast proliferation is one of the well-known mechanisms for postoperative intraabdominal adhesion formation. Inhibition of fibroblast proliferation is an attractive field of investigation in the prevention of adhesions. Mitomycin C (MMC) is a cytotoxic agent that alkylates and crosslinks DNA and also inhibits fibroblast proliferation up to a few weeks. We aimed to determine the effect of MMC on the prevention of adhesions.

MATERIALS AND METHODS

Generation of adhesions in rats by brushing a 1-cm(2) area of the cecum and the peritoneum on the right side of the abdominal wall was followed by intraperitoneal administration of saline, 1 mg/kg MMC, and 0.5 mg/kg MMC in saline. After 45 days, formation of adhesions was graded.

RESULTS

The average adhesion scores of the control, and MMC (1 mg/kg), MMC (0.5 mg/kg) groups were 3.2 +/- 0.7, 0.8 +/- 0.6, and 0.7 +/- 0.8, respectively. Adhesion scores of the two MMC-treated groups were significantly lower than that of the control group (P < 0.001). There was no difference between the two MMC groups (P > 0.05). No side effect of MMC was observed.

CONCLUSION

MMC was found to be very effective in the prevention of postoperative intraabdominal adhesions.

Polydiaxonon prevents adhesions in the rabbit model: a pilot report

PURPOSE

Restrictive strabismus is a common and difficult problem confronted by strabismologists. Several materials have been used to minimize the formation of adhesions after strabismus surgery with varying degrees of success. Polydiaxonon (PDS, Ethicon) is an absorbable, nontoxic, nonporous material. We used it as 25 and 50 microm thick sleeves to study its effectiveness in the prevention of adhesions.

METHOD

Eight eyes of four adult New Zealand White rabbits were used. To simulate the adhesions, a raw scleral bed was created under the superior rectus insertion in study animals and the muscle capsule facing the sclera was opened. Four study eyes had PDS sleeves inserted around the superior rectus; the other four served as controls. After 4 months the animals were killed. The surgical sites were inspected for adhesions. Light microscopy was also performed.

RESULTS

Virtually no adhesion formation was noted in the study eyes. In the control group, however, dense adhesions were seen. Light microscopy confirmed these results. No significant amount of foreign material was found. There was no toxicity resulting from PDS.

CONCLUSIONS

This demonstrated nearly complete prevention of adhesions in the rabbit model. PDS sleeves appear to have potential in surgery for restrictive strabismus.

Restricted ocular motility after orbital trauma--studies with an animal model

OBJECTIVE

Our purpose was to develop a quantitative model of restricted ocular motility (fat adherence syndrome) in the pig orbit to facilitate research into pathogenesis and treatment.

METHODS

Twenty eyes of 10 pigs were used in an attempt to create a fibrous adhesion between either the inferior rectus or the medial rectus muscle and the adjacent periorbita. Quantitative forced ductions were performed preoperatively and 6 weeks postoperatively with an electronic force gauge.

RESULTS

Forced ductions displayed a linear relationship to displacement over the range tested, both preoperatively and postoperatively. Although increased resistance to forced ductions was produced in 10 of the 20 (50%) eyes, the average changes were not statistically significant. The absolute change in force (Postoperative--Preoperative) was linearly related to the amount of ocular rotation. Reproducibility of measurements was markedly improved by the use of a motorized forced duction apparatus compared with manual rotation.

CONCLUSIONS

The results from this study, and those from previous work, suggest that the classic fat adherence syndrome is an uncommon event, even after significant soft tissue injury in the orbit. Further studies are needed to more completely define the risk factors and pathogenesis of the fat adherence syndrome and the suitability of the pig orbit as a model.

Intraoperative sponge 5-fluorouracil to reduce postoperative scarring in strabismus surgery

INTRODUCTION

To determine whether 5-fluorouracil is effective in reducing scarring after strabismus surgery we used rectus muscle surgery in experimental animals to compare a single intraoperative dose of 5-fluorouracil with mitomycin C and to compare results in similarly treated controls not receiving these antimetabolites.

METHODS

Muscle resections were performed on eight rabbits (16 eyes). Four eyes had 5-fluorouracil (50 mg/ml), and four eyes received mitomycin C (0.2 mg/ml), each of which was applied during surgery on an ophthalmic sponge for 5 minutes. Eight eyes served as controls. Six weeks after surgery conjunctival vascularity, muscle length-tension curves, muscle disinsertion force, and the histologic degree of scarring were assessed.

RESULTS

The mitomycin C-treated eyes clearly had more conjunctival avascularity and a lower disinsertion force. Both treated groups had flatter length-tension curves and less scarring on histologic examination than the control eyes.

CONCLUSIONS

Antifibroproliferative therapy with intraoperative sponge 5-fluorouracil appears as effective as, and is possibly safer than, mitomycin C. It may be a useful adjunct in recurrent strabismus surgery or in other situations where a risk of excessive postoperative scarring exists.