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

An in vitro comparison of human corneal epithelial cell activity and inflammatory response on differently designed ocular amniotic membranes and a clinical case study

Amniotic membrane (AM) is a naturally derived biomaterial with biological and mechanical properties important to Ophthalmology. The epithelial side of the AM promotes epithelialization, while the stromal side regulates inflammation. However, not all AMs are equal. AMs undergo different processing with resultant changes in cellular content and structure. This study evaluates the effects of sidedness and processing on human corneal epithelial cell (HCEC) activity, the effect of processing on HCEC inflammatory response, and then a case study is presented. Three differently processed, commercially available ocular AMs were selected: (1) Biovance®3L Ocular, a decellularized, dehydrated human AM (DDHAM), (2) AMBIO2®, a dehydrated human AM (DHAM), and (3) AmnioGraft®, a cryopreserved human AM (CHAM). HCECs were seeded onto the AMs and incubated for 1, 4 and 7 days. Cell adhesion and viability were evaluated using alamarBlue assay. HCEC migration was evaluated using a scratch wound assay. An inflammatory response was induced by TNF-α treatment. The effect of AM on the expression of pro-inflammatory genes in HCECs was compared using quantitative polymerase chain reaction (qPCR). Staining confirmed complete decellularization and the absence of nuclei in DDHAM. HCEC activity was best supported on the stromal side of DDHAM. Under inflammatory stimulation, DDHAM promoted a higher initial inflammatory response with a declining trend across time. Clinically, DDHAM was used to successfully treat anterior basement membrane dystrophy. Compared with DHAM and CHAM, DDHAM had significant positive effects on the cellular activities of HCECs in vitro, which may suggest greater ocular cell compatibility in vivo.

Treatment and prevention of ocular motility restrictions with amniotic membrane transplantation

We intend to investigate the indications, complications, and final results of amniotic membrane (AM) transplantation in ocular motility restrictions. Surgeons have tried to prevent restrictive adhesions between the extraocular muscles and surrounding tissues because they cause unpredictable results. AM transplantation wrapping extraocular musculature has been proposed as a technique with good results for this purpose. A search was carried out in Medline, Embase, Cochrane Library and Clinicaltrial, Lilac and Ibecs databases, using the indexed terms" amnion", "strabismus," "strabismus-subheading-surgery" and "ocular motility disorders." The only exclusion criteria were studies conducted in non-humans or studies with insufficient data on eye motility. No study was discarded for analysis because of language, age or methodology. This review includes 165 patients (223 eyes), with a mean follow-up of 11.49 months. The mean age was 21 years old, 47% were males and 57% were children. 14 studies conducted in humans were eligible: 4 single case, 8 case series, 1 cohort study and 1 randomized clinical trial. In the vast majority of these papers, use of AM transplantation to treat (12 out of 14 papers) or either to prevent (2 out of 14 papers) motility restrictions or restrictive strabismus secondary to muscular adhesions. All the studies except one presents very favorable results improving postsurgical eye motility. The cryopreservation method was more widely used, presenting a good safety profile with few adverse effects in the short and medium term. Significant improvement was reported in most patients after the use of amniotic membrane transplantation to treat or prevent ocular motility limitations. Very few complications or adverse effects were documented.

Expression of Lubricin in the Human Amniotic Membrane

PURPOSE

Lubricin, a boundary lubricant, is the body's unique antiadhesive, antifibrotic, antifriction, and antiinflammatory glycoprotein. This amphiphile is produced by numerous tissues and acts to regulate a number of processes, such as homeostasis, shear stress, tissue development, innate immunity, inflammation, and wound healing. We hypothesize that lubricin is also synthesized and expressed by the amniotic membrane (AM), which also possesses antiadhesive, antifibrotic, and antiinflammatory properties. We also hypothesize that lubricin, at least in part, mediates these AM capabilities. Our goal was to test our hypothesis.

METHODS

We obtained multiple samples of fresh, cryopreserved (CP), and freeze-dried (FD) human AMs, as well as fresh placental tissue as positive controls, and processed them for light microscopy, immunofluorescence, and western blot analyses. We also evaluated the ability of recombinant human lubricin to associate with FD-AMs.

RESULTS

Our results demonstrate that all fresh placental, fresh AM, and CP-AM samples contained lubricin. Lubricin was expressed in placental chorionic villi, AM epithelial and stromal cells, and CP-AM epithelia. No lubricin could be detected in FD-AMs but could be restored in FD-AMs after overnight incubation with recombinant human lubricin.

CONCLUSIONS

This study supports our hypothesis that lubricin is expressed in human AMs. In addition, our data show that preservation methods influence the extent of this expression. Indeed, the disappearance of lubricin in FD-AMs may explain why dried AM reportedly loses its antiinflammatory and antiscarring abilities. It is possible that lubricin may mediate, at least in part, many of the biological properties of AMs.

Management of stretched scar- induced secondary strabismus

Background

To determine characteristics and management of consecutive or recurrent strabismus secondary to stretched scar.

Methods

This is a retrospective review of all patients diagnosed with late secondary consecutive or recurrent strabismus due to stretched scar from 2012 to 2017. The diagnosis of stretched scar was made in any case of late (≥ 1 month) consecutive or recurrent strabismus associated with underaction of the previously operated muscle. The diagnosis was confirmed intraoperatively by negative forced duction test and the characteristic appearance of the scar tissue. Surgical correction involved excision of the scar tissue with muscle re-attachment to the sclera using non-absorbable sutures. Study parameters include improvement in secondary deviations, degree of muscle underaction and diplopia.

Results

21 consecutive and 6 recurrent cases of stretched scar –induced strabismus were identified and all cases were associated with variable degrees of limited ocular duction. After surgical correction of the stretched scar, consecutive deviations in the form of consecutive esotropia and exotropia were corrected by means of 26.1PD and 65.6PD while recurrent deviations in the form recurrent exotropia and recurrent hypertropia were corrected by means of 34.3PD and 11PD respectively with significant improvement of limited ocular ductions. 21 patients had diplopia at presentation and all were improved after surgery.

Conclusion

management of stretched scar –induced secondary strabismus by excision of the stretched scar and muscle fixation to the sclera using non-absorbable sutures significantly corrects secondary deviations and improves limitation of ocular duction.

Amniotic Membrane Transplantation in Strabismus Surgery

PURPOSE

Adhesions between the extraocular muscles and surrounding tissues pose a main cause of failure of strabismus reoperations. Amniotic membrane (AM) transplantation during extraocular muscle surgery, to prevent the formation of adhesions, has been a subject of research during the past decade. This review aims to determine the value, indications, and tips on usage of AM transplantation during strabismus surgery.

MATERIALS AND METHODS

All references cited in PubMed in English were searched using the key words: amniotic membrane strabismus or amniotic membrane extraocular muscles, and a brief summary of these was described. In addition, certain articles were chosen to provide introductory information on wound healing and fibrosis, AM properties and how it works after transplantation, and AM processing and preservation.

RESULTS

AM used for transplantation during extraocular muscle surgery may be cryopreserved, dried, or fresh. It may be oriented with its stroma or epithelium towards the muscle. It may or may not be fixed with sutures. What were the best choices? Various studies attempted to answer these questions. Many of the studies reviewed, however, were inconclusive or contradictory. Fresh AM seemed effective, but carried a risk of transmission of communicable diseases. Dried membrane was not of value in preventing adhesions. Histopathologically, cryopreserved membrane prevented the development of adhesions in the region of its presence, regardless of its orientation, and without the need for suture fixation. To accentuate this histopathological effect during clinical practice, it was recommended to utilize the largest segment possible of cryopreserved membrane and limit its usage to cases where adhesions are expected to be the main cause of failure of strabismus surgery.

CONCLUSION

Cryopreserved AM transplantation was safe and histopathologically effective in preventing adhesions. This effect was, however, less pronounced clinically. Its use during strabismus reoperations is merited if previous recommendations and precautions are considered.

Processed amniotic membrane for conjunctival reconstruction in complex strabismus surgery

INTRODUCTION

In ophthalmology amniotic membrane is usually used for the treatment of corneal ulcerations and chemical burns of the ocular surface. Also, it is useful in the treatment of conjunctival defects. There are few publications on the long-term outcomes with the use of amniotic membrane to replace the conjunctiva. In our cases, we used it in patients with restrictive strabismus or conjunctival problems during or following complex eye muscle surgery.

MATERIALS AND METHODS

In this retrospective case study, we reviewed the charts of the patients who had been treated with Ambio5® (IOP Inc. USA) for the replacement of conjunctiva in the treatment of conjunctival problems during or following complex eye muscle surgeries in our ophthalmology department between 2009 and 2015. Ambio5® is a processed dry, multi-layered amniotic membrane of 110-micron thickness. Inclusion criteria were the use of it in the treatment of conjunctival problems during or following complex eye muscle surgery.

RESULTS

Thirty-two patients were identified. Among the 32 identified patients, 7 patients (6 female, 1 male) had restrictive conjunctiva following complex strabismus surgery with functional problems or aesthetic conjunctival scarring requiring transplantation. The mean age of these patients was 47 years (range: 22-60 years). Mean follow-up time was 32 months (range 18-55 months). Only one of these seven patients suffered a discomfort related to conjunctival scarring. The other six patients had restrictive strabismus, four of them suffered from Graves' ophthalmopathy. All patients improved although three patients developed symblepharon. One of these patients needed revision because of a symblepharon.

DISCUSSION

The result of our study indicates that commercially prepared amniotic membrane is a good alternative graft to replace conjunctiva. It helps to prevent or cure restrictive strabismus, scarring of the conjunctiva with discomfort, and lack of conjunctiva. It is possible that commercially storable products may increase the risk of symblepharon, the reason is unknown.

Long-term follow-up of cryopreserved amniotic membrane transplant during strabismus reoperations: Up 85 months' follow-up

PURPOSE

To evaluate the long-term effect of cryopreserved human amniotic membrane transplant during strabismus reoperations.

METHODS

A total of 15 patients with persistent strabismus were included in a prospective study to evaluate the effect of wrapping the extra-ocular muscles with cryopreserved amniotic membrane during strabismus reoperations. The study end-point was the last follow-up visit. A successful outcome was defined as 0-10∆ of horizontal tropia and 0-4∆ of vertical tropia, with no limitation of ductions exceeding -1. A cosmetically acceptable outcome was defined as a tropia of 0-15∆.

RESULTS

Maximum follow-up was 85 months (mean: 25.4 ± 25.5 months). At the last follow-up visit, a successful outcome was achieved in 46.7%, a cosmetically acceptable outcome was achieved in 66.7%, and the mean ocular deviation angles improved from 38.60 ± 14.63∆, preoperatively, to 10.6 ± 11.08∆. Motility limitation on the final follow-up visit exceeded -1 in only 4/180 muscles (2.2%).

CONCLUSION

The effect of cryopreserved amniotic membrane transplantation on the success of strabismus reoperations was moderate in terms of ocular alignment. Its effect was more pronounced in terms of ocular motility. The latter better reflects the level of adhesions. No long-term complications were documented, denoting safety of cryopreserved amniotic membrane usage during strabismus reoperations.

A comparative study of different amniotic membrane orientations during extraocular muscle surgery in rabbits

PURPOSE

To histopathologically compare the effect of different orientations of cryopreserved human amniotic membrane (AM) transplant during extraocular muscle surgery in rabbits.

METHODS

Fifty-two albino rabbit eyes underwent 4-mm resection of the superior rectus. Eyes were randomly divided into four groups. In Group C (Control group, 16 eyes) the muscle was not wrapped with amniotic membrane. In the three AM groups, cryopreserved AM was wrapped around the muscle, oriented with either its stroma (Group S, 15 eyes) or epithelium (Group E, nine eyes) towards the muscle, or folded on itself with the epithelium externally (Group F, 12 eyes). The rabbits were sacrificed and the eyes were enucleated 6 weeks after surgery. Histopathological examination was conducted for periamniotic, foreign body, scleral, and conjunctival inflammation, conjunctival vascularity, adhesions and muscle fibrosis.

RESULTS

In all AM eyes, the AM was surrounded by periamniotic inflammation, with no adhesions detected between the muscle and surrounding tissues in the segment where the AM was present, but detected elsewhere. Adhesions were detected in all group C eyes. Foreign body inflammation was significantly less in Group C than in each of the AM groups (p < .05), but was insignificantly different among the three AM groups (p > .05). Scleral inflammation was absent in all specimens. No significant differences were noted among all groups in terms of conjunctival vascularity, conjunctival inflammation, or muscle fibrosis (p > .05).

CONCLUSIONS

All AM orientations were equally effective in preventing the development of postoperative adhesions between the extraocular muscle and surrounding tissues.

Cryopreserved rabbit amniotic membrane alleviated inflammatory response and fibrosis following experimental strabismus surgery in rabbits

We evaluate the ability of cryopreserved rabbit amniotic membrane (AM) transplantation to reduce postoperative inflammation and the extent of fibrosis following experimental strabismus surgery. Ten white rabbits underwent bilateral superior rectus (SR) muscle resection. In the left eye, the resected SR muscle was wrapped with cryopreserved rabbit AM. The right eye underwent SR resection only and served as a control. The eyes were enucleated 4 weeks after strabismus surgery. The degree of postoperative inflammatory infiltration, the extent of fibrosis, and profile of the relative expression of inflammatory mediators in the SR muscle were evaluated and compared between the two groups by histological analysis and real-time polymerase chain reaction (PCR). There were statistically meaningful differences in the degree of postoperative inflammatory infiltration and extent of fibrosis between the eyes treated with cryopreserved rabbit AM after SR resection and those underwent SR resection only. A significant decrease in the expression of inflammatory cytokines [interleukin (IL)-12a, IL-12b, IL-17f, and tumor necrosis factor- alpha (TNF-α)], and a markedly increased expression of anti-inflammatory cytokines (transforming growth factor-beta-1(TGFβ-1) and IL-10) were observed in the eyes treated with cryopreserved rabbit AM. In this study, we demonstrate that cryopreserved rabbit AM is effective in reducing postoperative inflammation and extent of fibrosis in a rabbit model of strabismus surgery. Our results imply that cryopreserved AM allograft has anti-inflammatory and anti-scarring properties that can prevent postoperative adhesions following strabismus surgery.

Placental Membranes for Management of Refractory Cutaneous Sinus Tracts of Surgical Origin: A Pilot Study

Despite advances in surgical technique, postoperative complications may lead to refractory cutaneous sinus tracts or tunnels. Negative pressure wound therapy is difficult to apply in longer tracts with a narrow diameter opening and conservative treatment failures ultimately necessitate surgical revisions. The aim of this pilot study was a clinical utility assessment of two different commercial placental membrane products for refractory cutaneous sinus tracts of surgical origin. Patients were treated with viable cryopreserved placental membrane (vCPM, n = 6) or devitalized dehydrated amnion/chorion membrane (dHACM, n = 6). The primary outcome measurement was the proportion of complete sinus tract depth resolution without exudate. Secondary endpoints included 4-week percent reduction in sinus tract probing depth and peri-tract wound surface area, days and number of grafts to resolution, number of wound-related infections, and 1-year recurrence rate for closed sinus tracts. All vCPM patients demonstrated complete sinus tract resolution compared to zero closures in the dHACM group (p = 0.00216). The vCPM group achieved greater percent reduction in probing depth (73.3 ± 21.9 versus −4.4 ± 91.3) and surrounding wound surface area (34.8 ± 86.8 versus −279.3 ± 454.9) at 4 weeks than dHACM. The use of viable intact cryopreserved placental membrane has demonstrated positive clinical outcomes for the treatment for refractory exudative sinus tracts and may be an alternative to repeat surgical intervention.

Restrictive problems related to strabismus surgery

Strabismus surgery may be responsible for some restrictions in ocular motility that may cause new problems after surgery. Most of the time these restrictions present as a complex motility problem after surgery that requires further treatment. There may be various reasons that cause motility restriction following strabismus surgery. Those are excessive shortening or inadvertent capture of extraocular muscles, transposition procedures and, the most challenging problem, postoperative scar tissue-adhesion formation. In this review the potential reasons for postoperative restrictive problems, preventive measures and finally the treatment options for such problems are overviewed.

Long-term efficacy of glycerine-processed amniotic membrane transplantation in patients with corneal ulcer

PURPOSE

The aim of this study was to determine the long-term treatment efficacy of glycerine-preserved human amniotic membrane transplantation in patients suffering from corneal ulcers.

METHODS

This was a retrospective, non-controlled, monocentric analysis. Included were patients with corneal ulcers that were non-responsive to ointment or contact lenses and had been treated by amniotic membrane transplantation with either the overlay or sandwich procedure. Analysis parameters were visual acuity before and following treatment, recurrence rate and subjective comfort at the last follow-up.

RESULTS

Of the 371 amniotic membrane transplantations that were conducted, 135 surgical treatments in 108 patients (51.9% male, 48.1% female; mean age 63.7 years) met the inclusion criteria. In total, 99 overlay and 36 multilayer amniotic membrane transplantations were performed. The follow-up period was 47.5 ± 66.7 weeks (mean ± SD). The recurrence rate at the last follow-up was 47.8% with overlay membranes and 51.8% with the sandwich technique. There was no significant change in best-corrected visual acuity following treatment with overlays (p = 0.219) or sandwich procedure (p = 0.703). At the last follow-up, 72.1% (overlay) and 78.3% (sandwich) of the patients reported either no pain or increased comfort.

CONCLUSION

The recurrence rates and changes in visual acuity following overlay or sandwich amniotic membrane transplantation in patients suffering from corneal ulcer were lower than reported elsewhere in the literature. More than half of the patients profited from each of the amniotic membrane transplantation techniques with respect to recurrence and postoperative comfort.

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.

Subconjunctival amniotic membrane free graft in rabbit eyes: effects on fibrovascular reaction

PURPOSE

The purpose of our study is to investigate the effect of subconjunctival amniotic membrane free graft on subconjunctival fibrovascular reaction.

METHODS

Twelve healthy male white New Zealand rabbits were used for the study. The rabbits were divided randomly into two groups: Study Group (n=6) and Control Group (n=6). In the Study Group, a 4mm limbal incision was made and a 4×4mm subconjunctival pocket was created with blunt dissection. A 4×4mm single layer of free amniotic membrane was placed in the pocket in an epithelium-up fashion without suturing. The limbal opening was secured with 10-0 nylon sutures on both sides. In the Control Group, a 4mm limbal incision was made, a 4×4mm subconjunctival pocket was created with blunt dissection, and the limbal opening was closed with 10-0 nylon sutures on both sides. After the first month, sclero-conjunctival blocks were obtained from the operated area and sections were stained with hematoxylin and eosin, Masson trichrome, and Ki67, SMA and CD34 antibodies.

RESULTS

The number of fibroblasts, lymphocytes and macrophages was significantly higher in the Study Group than in the Control Group. The number of Ki67- and SMA-positive cells, and CD34-positive vessels was also significantly higher in the Study Group. Amniotic membrane appeared to form folds in all the specimens.

CONCLUSION

The higher fibrovascular reaction shown by our histopathological examination indicates that free human amniotic membrane grafting without suturing is not useful in decreasing the subconjunctival fibrovascular reaction at the first postoperative month in rabbit eyes.

Effect of cauterization on the subconjunctival fibrovascular reaction in rabbit eyes

OBJECTIVE

The purpose of our study is to investigate the effect of episcleral cauterization during conjunctival autograft surgery on subconjunctival fibrovascular reaction in rabbit eyes.

METHODS

Twenty-four healthy male New Zealand white rabbits were divided into Control Group (n = 12) and Cautery Group (n = 12). In the Control Group, a 4 × 4 mm free conjunctival graft was elevated, the underlying Tenon's capsule was excised, and the free graft was sutured back to its original place with 10-0 nylon sutures. In the Cautery Group, in addition to the same surgical steps, the episclera was cauterized with six gentle touches before the conjunctival graft was sutured back to its original place. The scleroconjunctival block of the operated area was excised at the first month. The sections were stained with hematoxylin and eosine and Masson trichrome and were evaluated using light microscopy.

RESULTS

Subconjunctival collagen fibers were increased, and the fibroblast density increased more significantly in the Cautery Group than in the Control Group. The groups were similar regarding vascularization, lymphocytic, and plasmocytic infiltration. Macrophage density was normal in all animals in both groups.

CONCLUSION

Our histopathological examinations indicate that cauterization seems to lead to an increase in subconjunctival fibrosis at the first postoperative month in rabbit eyes.

The effect of a temperature-sensitive poloxamer-alginate-CaCl2 mixture after strabismus surgery in a rabbit model

PURPOSE

To determine the efficacy of a temperature-sensitive poloxamer-alginate mixture in reducing adhesions after strabismus surgery in a rabbit model.

METHODS

The superior rectus muscle was recessed in each of 36 eyes from 18 rabbits. One randomly assigned eye in each rabbit was treated with a poloxamer-alginate mixture (PA group); the other eye was treated with a subconjunctival injection of saline (control group). The adhesions between the superior rectus muscle, sclera, and conjunctiva were clinically evaluated by a masked observer at 1 day, 1 week, and 4 weeks after surgery. Inflammation was analyzed by hematoxylin and eosin staining and anti-CD11b staining. Late fibrosis was assessed by the Masson trichrome and α-smooth muscle actin staining. Adhesion, inflammation, and fibrosis were graded on a scale of 0-4.

RESULTS

There was no significant between-group difference in the degree of adhesion at 1 day and 4 weeks after surgery. However, the degree of adhesion in the PA group was lower than that in the control group at postoperative week 1 (P < 0.05). Acute inflammation was similar between the groups (P > 0.05). At postoperative week 4, inflammatory cell infiltration was reduced in the PA group (P = 0.046). A significant between-group difference in late fibrosis at postoperative week 4 was observed through the Masson trichrome (P = 0.024) and α-smooth muscle actin staining (P = 0.025).

CONCLUSIONS

The poloxamer-alginate mixture significantly decreased adhesion after strabismus surgery in a rabbit model. Additional studies are warranted to evaluate the use of this mixture in preventing postoperative adhesions.

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.

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.

Amniotic membrane implantation to reduce extraocular muscle adhesions to a titanium implant

Amniotic membrane grafts are used extensively for ocular surface reconstruction. We describe the case of a 66-year-old man with traumatic, restrictive strabismus. Amniotic membrane was applied to resolve symblepharon between the globe and lids and also to prevent re-formation of adhesions between extraocular muscles and adjacent titanium plates placed during prior surgery.