Serious complications of topical mitomycin-C after pterygium surgery

Meta-analysis on the recurrence rates after bare sclera resection with and without mitomycin C use and conjunctival autograft placement in surgery for primary pterygium

BACKGROUND/AIMS

Bare sclera resection with and without use of mitomycin C and conjunctival autograft placement are three surgical techniques currently in use for the treatment of primary pterygium. The purpose of this study was to determine through a meta-analysis the risk for postoperative pterygium recurrence comparing the three surgical treatment modalities.

METHODS

A search through Medline for randomised controlled clinical trials comparing at least two of the three surgical techniques in the treatment of primary pterygium, along with a hand search of all references in relevant papers, was conducted. All eligible clinical trials were graded for quality utilising the Detsky score; those studies with a score of 0.5 or greater were included. The main outcome measurements were the pooled odds ratios and 95% confidence intervals for the risk of pterygium recurrence. These were calculated utilising the Mantel-Haenszel method.

RESULTS

Five eligible studies with an adequate quality score were retrieved, three comparing bare sclera resection with and without mitomycin C use, one comparing bare sclera resection with conjunctival autograft placement, and one comparing both. The pooled odds ratio for pterygium recurrence in patients who had only bare sclera resection was 6.1 (95% confidence intervals, 1.8 to 18.8) compared with the patients who had conjunctival autograft placement and 25.4 (9.0 to 66.7) compared with the patients who received mitomycin C.

CONCLUSIONS

The odds for pterygium recurrence following surgical treatment of primary pterygium are close to six and 25 times higher if no conjunctival autograft placement is performed or if no intra/postoperative mitomycin C is used, respectively. Surgeons and clinical triallists should not be encouraged in the use of bare sclera resection as a surgical technique for primary pterygium.

Intraoperative mitomycin C to prevent recurrence of pterygium after excision: a 30-month follow-up study

OBJECTIVE

The purpose of the study was to examine the efficacy of intraoperative mitomycin C (MMC) in preventing recurrence of pterygium after excision and the postoperative complications encountered.

DESIGN

The study design was a prospective, randomized, clinical trial.

PARTICIPANTS

A total of 180 primary and recurrent pterygia were recruited for the study. They were randomized into five groups: A, control with no MMC; B, 0.02% MMC for 5 minutes; C, 0.04% MMC for 5 minutes; D, 0.02% MMC for 3 minutes; and E, 0.04% MMC for 3 minutes.

INTERVENTION

All patients received pterygium excision with or without the above four modes of intraoperative MMC application.

MAIN OUTCOME MEASURES

Recurrence of pterygium and postoperative complications such as superficial scleral melting were measured.

RESULTS

At a mean follow-up of 30 (groups A-C) and 20 months (groups D and E), the respective recurrence rates in groups A through E were 75%, 8.3%, 8.6%, 42.9%, and 22.9%. There were two cases of postoperative superficial scleral melting in group C. Otherwise, no major postoperative complications were encountered.

CONCLUSIONS

The midterm results of a single intraoperative application of MMC at the concentration of 0.02% for 5 minutes are encouraging. Its application as an adjunctive therapy for the surgical treatment of pterygium appeared to be safe and effective. However, because of the possibility of serious late complications, the authors suggest that this procedure be reserved for patients who have high probability of recurrence after excision of pterygium.

Topical mitomycin C chemotherapy for conjunctival melanoma and PAM with atypia

AIM

To evaluate topical mitomycin C (MMC) chemotherapy in the treatment of conjunctival melanoma and primary acquired melanosis with atypia.

METHODS

In a phase I clinical trial, 10 patients with conjunctival melanoma and/or primary acquired melanosis with atypia were treated with topical MMC 0.04% four times daily. Four patients were given MMC for 28 days as a primary treatment. Six patients were treated with MMC for 7 days after excision and cryotherapy in an effort to improve local control. In this series, 10 patients have been followed for an average of 29 months.

RESULTS

All patients were noted to develop transient keratoconjunctivitis during treatment. One patient also developed a transient corneal epithelial defect. Decreased conjunctival pigmentation was noted in the four patients where topical chemotherapy was used as a primary treatment. Nodular tumours were resistant to topical MMC chemotherapy. Of the six patients treated within 2 weeks after primary excision and cryotherapy, there has been no tumour recurrence or symblepharon formation. Nine of the 10 study patients have maintained within one line of their pretreatment visual acuity. No retinal or optic nerve toxicity was noted.

CONCLUSION

Since no complications which might preclude further investigation of topical MMC chemotherapy occurred, it was concluded that topical MMC chemotherapy was tolerated as a treatment for conjunctival melanoma and primary acquired melanosis with atypia.

Conjunctival autograft versus topical mitomycin C in treatment of pterygium

A prospective study was carried out to assess the recurrence rate of pterygium with conjunctival autograft versus the use of topical mitomycin C. In 27 eyes undergoing pterygium excision with conjunctival autograft, the recurrence rate was found to be 25.9% after 1 year mean follow-up. In the second group of 32 eyes, pterygium was removed using the bare sclera method. All these patients received post-operatively 0.2 mg/ml (0.02%) topical mitomycin C twice a day for 5 days. At 1 year mean follow-up, the recurrence rate in this group was 9.4%. Although the difference was not statistically significant, the number of recurrences was lower in the mitomycin-C-treated group than in patients undergoing conjunctival autograft.

Trabeculectomy augmented with mitomycin C application under the scleral flap

AIM

The authors investigated the safety and intraocular pressure (IOP) lowering effectiveness of trabeculectomy augmented with mitomycin C application beneath the scleral flap, and assessed the influence of preoperative risk factors on the surgical outcome.

METHODS

A retrospective study of 72 consecutive high risk eyes undergoing trabeculectomy with adjunctive mitomycin C (0.2 mg/ml) applied under the scleral flap for 5 minutes was performed. Each eye was ascribed a score based on the number of preoperative risk factors, and categorised into one of three risk factor groups. Success was described as unqualified where IOP was < or = 21 mm Hg without medication and qualified where antiglaucomatous therapy was required to maintain it at such a level. A life table analysis of IOP control was calculated.

RESULTS

The mean IOP (SD) fell from a preoperative level of 28.4 (6.9) to a level of 16.63 (8.06) mm Hg at the last follow up (paired Student's t test: p < 0.0001). Fifty two eyes (72%) were classed as unqualified successes. The survival rates did not differ significantly between different risk factor groups (log rank test: chi 2 = 0.967, p > 0.1). The incidence of postoperative complications compared favourably with reports of mitomycin C application between Tenon's capsule and the undissected scleral bed.

CONCLUSION

The results illustrate that mitomycin C applied beneath the scleral flap during trabeculectomy in high risk eyes is associated with a success rate comparable to other modes of application. The incidence of potentially serious complications such as conjunctival wound leak and prolonged hypotony was lower than previously published data reporting sub-Tenon's administration of mitomycin C. The number and nature of preoperative risk factors do not appear to influence the surgical outcome. A possible mechanism of action is proposed.

Transplantation of amniotic membrane and limbal autograft for patients with recurrent pterygium associated with symblepharon

AIM

Treatment of recurrent pterygium associated with symblepharon requires both suppression of fibrosis and reconstruction of limbal barrier. To achieve this, human amniotic membrane was transplanted and limbal autografts performed.

METHODS

Four patients with severe symblepharon resulting from multiple surgeries for pterygium were treated. Human amniotic membrane was obtained at caesarean section and preserved until surgery. After excision of the fibrous tissues, the amniotic membrane was placed on the sclera, and a limbal autograft transplantation was performed using limbal tissues taken from the affected eye.

RESULTS

Recurrence of symblepharon was not observed in any of the patients and significant suppression of the subconjunctival fibrosis was achieved. Ocular movement improved in all cases. Complete remission of pterygium regrowth occurred in three cases, and a slight (about 1 mm) recurrence occurred in one case. The limbal donor site showed the presence of mild depressions without the formation of pseudopterygium.

CONCLUSION

Transplantation of human amniotic membrane with a limbal autograft appears to be a promising surgical treatment for reconstructing the ocular surface in patients with recurrent pterygium associated with symblepharon.

Primary glaucoma triple procedure in patients with primary open-angle glaucoma: the effect of mitomycin C in patients with and without prognostic factors for filtration failure

PURPOSE

To investigate the effect of adjunctive mitomycin C on primary glaucoma triple procedure in patients with primary open-angle glaucoma with and without one or more of the prognostic factors for filtration failure of primary glaucoma triple procedure. Those factors include being of African-American race, having a preoperative intraocular pressure of 20 mm Hg or more on maximum tolerated medications, and being on two or more medications preoperatively.

METHODS

Study patients consisted of 197 consecutive patients with primary open-angle glaucoma who were randomly assigned to receive either no adjunctive mitomycin C (101 eyes of 101 patients) or to receive adjunctive subconjunctival mitomycin C (96 eyes of 96 patients) during the primary glaucoma triple procedure. Kaplan-Meier survival analysis comparisons were made between respective subgroups with and without prognostic indicators for filtration failures using a relatively stringent set of criteria for filtration success of primary glaucoma triple procedure.

RESULTS

There was no statistically significant (P = .117) difference in filtration success of primary glaucoma triple procedure between the control and mitomycin C groups. Adjunctive mitomycin C significantly (P < .05) improved the filtration outcome of the primary glaucoma triple procedure in the subgroups with each of the three prognostic factors for filtration failure of primary glaucoma triple procedure. On the other hand, in the subgroups without the prognostic factors, adjunctive mitomycin C did not significantly (P > .05) change the filtration outcome of the primary glaucoma triple procedure.

CONCLUSION

These findings establish the basis for selective use of mitomycin C in patients with primary open-angle glaucoma undergoing primary glaucoma triple procedure.

Mitomycin C reduces scar formation after excimer laser (193 nm) photorefractive keratectomy in rabbits

Sixteen eyes of eight rabbits were randomised to either mitomycin C or Balanced Salt Solution (BSS) application after photorefractive keratectomy (PRK). Regular examinations of wound healing and haze were performed with the slit lamp. The animals were killed between 1 and 26 weeks after treatment, and the corneas examined by light and electron microscopy. While the grade of haze showed no relevant differences between the two groups, scar tissue was found histologically in the mitomycin group in only 1 of 8 corneas compared with 5 of 8 in the BSS group. A marked reduction in keratocytes in all mitomycin-treated corneas and a normal density of keratocytes in the BSS group was observed. Mitomycin reduced the number of keratocytes in the treated corneas, leading to less scar formation but not to a reduction in haze. Since no morphological correlate has been found, haze remains unexplained in the mitomycin-treated corneas.

Long-term results and complications after trabeculectomy with a single per-operative application of 5-fluorouracil

We retrospectively evaluated a consecutive series of 45 patients (45 eyes) who underwent trabeculectomy augmented with a single intra-operative 5 minute application of 5-fluorouracil (5-FU; 25 mg/ml). All patients were at an increased risk of subconjunctival fibrosis and surgical failure. The mean follow-up period was 24 months (range 12-42, SD 6.9). The mean pre-operative intraocular pressure (IOP) was 29.1 mmHg (SD 6.1) and the mean IOP at the last post-operative visit was 16.6 mmHg (SD 6.4) (p < 0.0001) with a mean IOP reduction of 42%. The number of medications reduced from a mean of 2.3 (SD 0.7) pre-operatively, to 0.8 (SD 0.7) post-operatively (p < 0.0001) and 22 eyes (49%) required no topical treatment for IOP control. An IOP of 21 mmHg or less with or without medications was achieved in 80% of cases. There was no significant difference in final IOP or success rate over time between low- and high-risk patients, although the low-risk patients did better in the first 12-18 months. Complications included hypotony maculopathy in 2 cases (4%), leaking bleb in 5 cases (11%) and giant bleb in 1 case (2%), giving a total of 8 cases (18%) with bleb-related sequelae. In the short to medium term, a single per-operative application of 5-FU is a useful adjunctive treatment during glaucoma filtering surgery for low- to moderate-risk cases, although a steady increase in the failure rate was associated with increasing length of follow-up.

Correction of lower eyelid retraction in thyroid eye disease: a randomised controlled trial of retractor tenotomy with adjuvant antimetabolite versus scleral graft

BACKGROUND/AIMS

Lower eyelid retraction in thyroid eye disease contributes to ocular discomfort and an unsightly appearance, especially if asymmetrical. The use of donor scleral grafts is effective in lengthening the lower eyelids but carries a risk of virus transmission. Other techniques, including those which do not use grafts, need to be compared with scleral grafts. Recurrent retraction is a recognised complication of thyroid eyelid surgery; therefore, the authors investigated the use of antimetabolites to reduce postoperative fibrosis.

METHODS

In this prospective randomised controlled trial of 25 patients (35 eyelids), the use of donor sclera in 20 lower eyelids (13 patients) was compared with partial tenotomy of the anterior part of the lower eyelid retractors (ALER) with adjuvant peroperative antimetabolite in 15 lower eyelids (12 patients). A 5 minute peroperative application of either 5-fluorouracil (25 mg/ml) in nine lower eyelids (eight patients) or mitomycin C (0.2 mg/ml) in six lower eyelids (four patients) was used to focally inhibit fibroblasts. Follow up ranged from 3 to 18 months (mean 7.8).

RESULTS

One month after surgery the results of both groups were similar. However, at 3 months after surgery the results of scleral grafting were better than tenotomy with antimetabolites: 3/12 patients (25%) treated with tenotomy and adjuvant antimetabolite required subsequent surgery using grafts for correction of recurrent retraction. There were no significant complications associated with the use of antimetabolites in the eyelid in the doses used in this study.

CONCLUSIONS

This randomised prospective trial shows that donor scleral grafts were more effective in the long term than partial tenotomy with adjuvant antimetabolite in the correction of lower eyelid retraction associated with thyroid eye disease. The use of peroperative antimetabolites in the lower eyelid was safe.

Mitomycin C treatment for conjunctival-corneal intraepithelial neoplasia: a multicenter experience

OBJECTIVE

The purpose of the study is to evaluate the efficacy and risks of topical mitomycin C (MMC) for conjunctival-corneal intraepithelial neoplasia (CCIN).

DESIGN

The study design was a clinical case series of CCIN.

PARTICIPANTS

Seventeen patients, 16 with biopsy-confirmed CCIN and 1 with invasive squamous cell carcinoma (SCC), were included in the study.

INTERVENTION

Patients received topical drops of MMC 0.02% to 0.04% four times daily from 7 to 28 days. Retreatment was done in cases of lesion recurrence.

MAIN OUTCOME MEASURES

The size of the CCIN before and after the treatment and ocular complications post-MMC application were evaluated.

RESULTS

Ten patients remained disease-free after one course of MMC application. In one case, residual CCIN remained very small without regrowth. In the one patient with invasive SCC and in five patients with CCIN, regrowth occurred within 6 months of the first treatment. After retreatment, invasive SCC and CCIN in an additional two patients were eradicated. In two cases, although the size of the lesions decreased after two and three applications of MMC, regrowth occurred, and the CCIN returned to its original size. In the final case, limited recurrence has occurred and no retreatment has been done. The complications of MMC use included mild-to-moderate conjunctival hyperemia and mild allergy, which resolved after discontinuation of the treatment. Severe pain manifested when treatment was longer than 14 days.

CONCLUSIONS

Application of topical MMC is an efficient treatment for most but not all cases of CCIN.

Clinical experiences of infectious scleral ulceration: a complication of pterygium operation

AIMS

To report the special clinical manifestations and determine the appropriate management of infectious scleral ulceration.

METHODS

A retrospective study was performed on 30 eyes with infectious scleral ulceration. Information was recorded on patients' age, onset and course of disease, pathogenic organism, clinical presentations, methods of diagnosis, treatment, and outcome.

RESULTS

10 cases (33.3%) were accompanied by corneal involvement. Subconjunctival abscess was noted in 16 cases (53.3%). 17 cases (56.7%) gave positive results of pathogen culture and all were Pseudomonas aeruginosa. Two cases had combined bacterial infections and one case was complicated by fungal infection. A total of 26 cases had surgical debridement in this series. Extensive involvement of the sclera with the presence of a 'tunnel lesion' or a 'satellite subconjunctival abscess' were found during debridement. All of the eyeballs involved were salvaged except one.

CONCLUSION

The results of this study were contrary to the poor prognosis presented in previous reports. Early and repetitive surgical debridement is believed to be mandatory in the intractable cases to shorten the admission period and to save these eyes.

Topical mitomycin C for the treatment of conjunctival and corneal epithelial dysplasia and neoplasia

PURPOSE

To evaluate the efficacy of topical mitomycin C in treating conjunctival and corneal epithelial dysplasia and neoplasia.

METHODS

Seven eyes of seven patients with conjunctival and corneal epithelial dysplasia and neoplasia were treated with one drop of topical mitomycin C 0.04% four times a day for 7 days in alternate weeks. The patients' charts were reviewed retrospectively. Patients with either multiple recurrences or extensive ocular surface involvement were treated. In all eyes, the diagnosis of epithelial dysplasia or neoplasia was confirmed by histopathology before the onset of therapy. Patients were examined at least every 14 days during treatment and examined at intervals after completion of treatment.

RESULTS

With topical mitomycin C, six eyes of seven patients had complete clinical regression of their conjunctival and corneal epithelial dysplasia and neoplasia. One eye of one patient had partial clinical regression of conjunctival and corneal epithelial dysplasia. Follow-up after completion of topical mitomycin C therapy and excision of residual disease ranged from 2 to 16 months (mean, 9 months; SD, 4.3 months) and was without clinical sign of recurrence. Topical mitomycin C therapy was associated with transitory ocular discomfort, conjunctival injection, tearing, photophobia, and punctate epithelial keratopathy.

CONCLUSION

In this small series of eyes, topical mitomycin C was effective as a treatment for conjunctival and corneal epithelial dysplasia and neoplasia.

Effect of mitomycin C on the optic nerve in rabbits

AIM

To prevent scarring after surgical optic nerve sheath decompression, it has been suggested that treating the area of fenestration with mitomycin C (MMC) might be effective. An animal model was used to test whether this toxic substance may cause optic neuropathy.

METHODS

The optic nerves of 15 rabbits were exposed to balanced salt solution (BSS) or mitomycin C (MMC) in a concentration of 0.2 or 0.5 mg/ml. The unoperated fellow eyes and the eyes that received BSS served as controls. Steady state visual evoked potentials (VEPs) at 40, 50, and 60 Hz were recorded before and 4 weeks after surgery. The nerves were examined by light and electron microscopy after 5 weeks.

RESULTS

VEPs in all non-operated eyes and eyes treated with BSS before and 4 weeks after surgery demonstrated responses at all three stimulus frequencies tested. Eyes operated with MMC had extinguished responses for one, two, or all the different temporal frequencies after 4 weeks with marked reduction in VEP amplitude. Eyes operated with MMC at a concentration of 0.5 mg/ml had significantly more reduced VEP responses than those where MMC 0.2 mg/ml was used. On histopathological examination, special stains for myelin and axons showed normal axons and myelin. On electron microscopy, no distinct abnormalities were seen among nerves operated with MMC and controls.

CONCLUSION

The data from this study suggest that in rabbits, the application of MMC to the optic nerve has a dose dependent toxic effect in the short term postsurgical follow up period. While a functional alteration could be demonstrated reproducibly by steady state VEPs, the extent was not obvious on histopathological examination of the nerves.

Transconjunctival application of mitomycin C in combination with laser sclerostomy ab interno: a long-term morphological study of the postoperative healing process

The precise mechanism whereby mitomycin C enhances IOP reduction in glaucoma filtering surgery still eludes us. Ten rabbits received full-thickness Nd:YAG laser sclerostomy ab interno and adjunctive intraoperative treatment with mitomycin C (MMC) applied topically over the intact conjunctiva (0.5 mg ml-1 for 5 min). A systematic ultrastructural analysis of the fistulas and surrounding tissue was then conducted in conjunction with clinical observations, over the ensuing 10 weeks. In order to investigate also the extent to which MMC impedes fistula occlusion in the absence of percolating aqueous humour, we created non-perforating ('half-thickness') sclerostomies ab interno in three additional rabbits, one with and two without MMC therapy. Transconjunctival MMC application resulted in no serious complications. Eight of the ten full-thickness fistulas remained patent throughout the study, maintaining significant IOP reduction; the other two sclerostomies were compromised by iris incarceration. The MMC-treated, half-thickness canal remained as a tissue-free cul de sac; the two non-treated ones became completely occluded within one week without having recourse to extraocular cell populations. MMC suppressed the migration and proliferation of fibroblasts, macrophages and clump cells from the episclera, sclera, ciliary body and iris root. Repolymerization of heat-damaged collagen was abortive; neosynthesis was not observed. Myofibroblasts were encountered in the vicinity of the sclerostomy canals, and, after the fifth week, these cells were also found to be deployed as a canal-lining layer, delimiting the lumen from the surrounding stroma along most of the fistula length. Towards the external ostium, this layer of myofibroblasts was incomplete or absent. Near the internal ostium, lining cells were derived from the corneal endothelium. The transconjunctival mode of applying MMC appears to be efficient. This antifibrotic drug exerts its inhibitory influence by suppressing not only cell migration and proliferation, but also phagocytic and synthetic activities. However, exposed tissues are not acellular, and amongst the populations present, myofibroblasts are found to dominate the scene. The canal-delimiting cellular lining may play a role in maintaining fistula patency in MMC-treated eyes.

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.

Intraoperative mitomycin in primary pterygium excision. A prospective, randomized trial

PURPOSE

Conjunctival autograft transplantation and postoperative mitomycin therapy are two adjuvant treatment methods shown to lessen the high pterygium recurrence rate seen with simple excision alone. The authors conducted a prospective, randomized study comparing these two techniques with a relatively new treatment method using intraoperative mitomycin application.

METHODS

Fifty patients with 56 primary pterygia were randomized to 1 of 3 treatment groups: conjunctival autograft (group 1), postoperative mitomycin 0.2 mg/ml four times a day x 7 days (group 2), and intraoperative mitomycin 0.4 mg/ml x 3 minutes (group 3). The mean follow-up time was 16 months (range, 6 to 28 months).

RESULTS

Recurrences developed in 4 (22.2%) of 18 eyes in group 1, 4 (21.1%) of 19 eyes in group 2, and 2 (10.5%) of 19 eyes in group 3. Complications developed in two, patients from group 2, scleral thinning managed successfully with a scleral patch graft, and epithelial toxicity that resolved on discontinuation of mitomycin on postoperative day 6. There were no complications in the other two groups.

CONCLUSIONS

Intraoperative mitomycin is a simple and effective alternative to postoperative mitomycin therapy, showing the lowest recurrence rate in their series with no toxicity during the study period. If the decision is made to use adjunctive mitomycin, the authors recommend intraoperative application over postoperative administration.

Combination intravenous ceftazidime and aminoglycosides in the treatment of pseudomonal scleritis

BACKGROUND

Pseudomonal scleritis is a serious and potentially blinding infection that usually is resistant to medical management.

METHODS

Results for three patients with pseudomonal scleritis who were treated with both topical anti-infectives and a combination of intravenous ceftazidime and aminoglycoside are presented in this case series.

RESULTS

All three patients had a rapid response to the addition of combination intravenous drug therapy to topical therapy; eradication of the infection and healing of the ocular surface occurred within 8 weeks. Only one patient, in whom cystoid macular edema developed, lost useful vision as a result of the infection.

CONCLUSIONS

Combination therapy with intravenous ceftazidime and aminoglycoside may be more effective than single-intravenous agents when used in addition to topical antibiotics and may obviate the need for adjunctive surgical procedures, such ascryotherapy, surgical extirpation, or conjunctival recession.

Effects of mitomycin C on the expression of proliferating cell nuclear antigen after filtering surgery in rabbits

BACKGROUND

The aim of the study was to evaluate the effects of mitomycin C on the cell replication activity in wound healing following experimental filtration surgery.

METHODS

Trabeculectomy with or without application of mitomycin C was performed on albino rabbit eyes. At 1, 4, 7, 14, and 28 days after surgery, the expression of proliferating cell nuclear antigen, a marker of cell proliferation, in the filtering site was examined immunohistochemically using a streptavidin-biotin complex method.

RESULTS

In control eyes that underwent trabeculectomy but did not receive mitomycin C, the number of immunoreactive cells increased 4-7 days after operation and decreased markedly at around 14 days. The filtering site was obstructed histologically at 4-7 days after operation. In the mitomycin C-treated eyes, immunoreactive cells appeared 4 days after surgery but disappeared by 7 days at the surgical site. The number of immunoreactive cells in the treated eyes was much lower than that in control eyes.

CONCLUSION

The cell replication activity was markedly inhibited by administration of mitomycin C. The filtering site remained open for 28 days after surgery, whereas it was completely obstructed within 7 days in control eyes. Immunocytochemistry for proliferating cell nuclear antigen, as used in this study, is a simple and reliable method for detection of cell replication activity.

5-Fluorouracil reduces scarring after strabismus surgery

PURPOSE

To examine the effect of topically administered 5-fluorouracil during strabismus surgery on post-operative scarring and the strength of the tendon-muscle union.

METHODS

Bilateral superior and inferior rectus muscle recessions were performed on 10 Stauffland white rabbits. The operated muscles in one eye received a 5-min topical application of 50 mg/mL solution of 5-fluorouracil (5-FU). The fellow eye received placebo treatment with a 5-min application of balanced sterile saline. Both eyes were enucleated 29 days postoperatively and examined for evidence of scarring. The tensile strength of both treated and untreated muscles was measured. Two additional rabbits received no surgery but had their eyes enucleated to serve as controls for tensile strength measurements.

RESULTS

A significant reduction (P = 0.0001) in the amount of scarring was noted in eyes treated with 5-FU. A reduction in the tensile strength of both operated groups compared with the unoperated groups (P = 2.72 x 10(-12)) was noted, with a small but significant difference between the two operated groups (P = 0.0423).

CONCLUSION

This study suggests that 5-FU may be a useful adjunctive therapy in strabismus surgery, especially when extensive postoperative scarring is expected.

Anterior nongranulomatous uveitis after intravitreal HPMPC (cidofovir) for the treatment of cytomegalovirus retinitis. Analysis and prevention

BACKGROUND AND OBJECTIVE

The authors characterize and analyze the incidence of a previously reported mild anterior nongranulomatous uveitis associated with intravitreal injections of (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC), also termed cidofovir (Vistide, Gilead Sciences, Foster City, CA). This is an acyclic nucleoside phosphonate analogue with a potent anticytomegalovirus effect. The authors also analyzed the effects of probenecid therapy, as well as prophylaxis with probenecid plus topical corticosteroids and cycloplegics on the course and outcome of the uveitis.

METHODS

Prospective case series from a tertiary referral center, which included 46 consecutive patients with acquired immune deficiency syndrome (AIDS) and cytomegalovirus (CMV) retinitis. There was a total of 130 injections in 69 eyes treated with 20 micrograms of intravitreal HPMPC. Forty-one patients (119 injections) received oral probenecid, 5 patients (11 injections) did not, and 21 patients (53 injections) received topical corticosteroids and cycloplegics as an adjuvant to probenecid in the prophylaxis of iritis.

RESULTS

Mild to moderate nongranulomatous iritis was seen in 26% of patients after their first injection (n = 12). Patients receiving probenecid prophylaxis after first injection had a significantly lower frequency of iritis versus patients who did not receive probenecid at the time of first injection (P = 0.0089). In contrast, treatment with topical corticosteroid and cycloplegics after injection did not statistically significantly affect the frequency of iritis in patients (P = 0.44). The development of iritis after a second injection of HPMPC was more likely if it had occurred after the initial injection (P = 0.015; Fisher's exact test). All cases of iritis were treated with topical corticosteroids and cycloplegics, and there was no permanent impairment of vision secondary to iritis after HPMPC injection in any eyes.

CONCLUSIONS

Anterior uveitis was seen in 26% of patients after first-time HPMPC injection. Concomitant use of probenecid appears to decrease the frequency of the iritis from 71% to 18% in patients with AIDS and CMV retinitis after the first intravitreal injection of HPMPC. Topical corticosteroid administration after injection (before iritis) was ineffective in preventing iritis treatment with topical corticosteroids and cycloplegics resulted in resolution of all iritis cases.

Mitomycin C dissolved in a reversible thermosetting gel: target tissue concentrations in the rabbit eye

AIMS

To determine whether a new, reversible thermosetting gel enhances mitomycin C transfer to target ocular tissues in the rabbit eye.

METHODS

A 0.1 ml solution of mitomycin C containing 0.22 microgram, 2.9 micrograms, or 28 micrograms of the agent dissolved in a reversible thermosetting gel consisting of methylcellulose, citric acid, and polyethylene glycol was injected subconjunctivally in 30 New Zealand albino rabbits. Scleral and conjunctival tissues were excised at 0.5, 1, 2, 4, or 24 hours after the injection and mitomycin C concentrations in these tissues were determined by high performance liquid chromatography. The concentration over time was approximated to a single exponential curve, and initial mitomycin C concentrations, time constants, and half life values were determined. Finally, the areas under the curves (AUCs) between 0.5 and 24 hours were calculated.

RESULTS

The mitomycin C concentrations in the target tissues were dose dependent and decreased rapidly over 24 hours. Both the initial mitomycin C concentrations as well as AUCs in these eyes treated with mitomycin C, dissolved in a reversible thermosetting gel, were higher than those in eyes treated similarly in a previous study in which the gel was not used.

CONCLUSION

Applied subconjunctivally in the rabbit eye, mitomycin C dissolved in the reversible thermosetting gel enhanced transfer of the agent to the sclera and the conjunctiva.

Dacryocystorhinostomy with intraoperative mitomycin C

PURPOSE

To observe the effect of intraoperative mitomycin C on the size of the osteotomy site after dacryocystorhinostomy.:

METHODS

A total of 15 eyes of 14 patients diagnosed with primary acquired nasolacrimal duct obstruction were assigned randomly to either a mitomycin C group or a control group. The surgical procedures in both groups were exactly the same, except that in the patients in the mitomycin C group, a piece of neurosurgical cottonoid soaked with 0.2 mg/ml mitomycin C was applied to the osteotomy site and then after 30 minutes was removed transnasally. Nasoendoscopic findings were recorded at the completion of the surgery and at 1 month, 3 months, and 6 months after surgery for the two groups. A computer-aided digitizer was used to calculate the surface area of the osteotomy site, and a Student's t test was used to compare the difference between the two groups.

RESULTS

All patients in the mitomycin C group remained symptom free after removal of their silicone tube (100% success), and there was one patient in the control group who had recurrent epiphora (87.5% success). Septo-osteotomy adhesion was found in two patients in the control group (25%), but there was no such adhesion found in the patients in the mitomycin C group. In the mitomycin C group, the average final surface area of the osteotomy at the end of the sixth postoperative month was 27.10 +/- 5.78 mm2, whereas that of the control group was only 10.83 +/- 3.37 mm2. Although the immediate postoperative surface area of the osteotomy showed no significant difference between the two groups, a statistically significant difference was noted at 6 months.

CONCLUSION

Intraoperative mitomycin C is effective in maintaining a larger osteotomy size. This modification may possibly improve success rates over the traditional dacryocystorhinostomy procedure.

Primary glaucoma triple procedure with or without adjunctive mitomycin. Prognostic factors for filtration failure

PURPOSE

The prerequisite for selective use of adjunctive mitomycin C (MMC) in primary glaucoma triple procedure (PGTP) is a better understanding of the prognostic factors. Therefore, the authors carried out the current study on the outcome of PGTP with and without adjunctive MMC to determine the prognostic factors for filtration failure of PGTP.

METHODS

The study patients consisted of 174 consecutive primary open-angle glaucoma (POAG) patients undergoing PGTP. They were assigned randomly to either no adjunctive MMC (93 eyes of 93 patients) or adjunctive subconjunctival MMC (81 eyes of 81 patients) during the PGTP. After surgery, the patients were examined at regular intervals for visual acuity, intraocular pressure (IOP) control, medical therapy requirements, and complications. Filtration failure was determined according to two different criteria: (1) a less stringent set of criteria (criterion I) and (2) a more stringent set of criteria (criterion II).

RESULTS

There were no statistically significant differences between the groups with and without adjunctive MMC with respect to postoperative IOP, number of medications, and visual acuity outcome during mean follow-up (+/- standard deviation) of 25.1 +/- 5.5 months (P > 0.05 for each). However, there were prognostic factors for filtration failure in the control group but not in the MMC group. Black race, diabetes mellitus, preoperative IOP greater than or equal to 20 mmHg, and number of preoperative medications greater than two were found to be significant prognostic factors for filtration failure by criterion I. Black race, preoperative IOP greater than or equal to 20 mmHg and number of preoperative medications greater than 1 were significant prognostic factors for filtration failure by criterion II.

CONCLUSION

There was no statistically significant difference in the overall outcome of PGTP between control and MMC groups of nonselected patients with primary open-angle glaucoma. Black race, diabetes mellitus (by criterion I only), preoperative IOP greater than or equal to 20 mmHg, and number of preoperative medications greater than 2 (by criterion I) or greater than 1 (by criterion II) were found to be significant independent prognostic factors for filtration failure of PGTP without adjunctive MMC but no with adjunctive MMC. The use of adjunctive subconjunctival MMC in PGTP may have to be selective, primarily in those patients with primary open-angle glaucoma with one or more of the prognostic factors for filtration failure.

Histopathological Comparison of Photorefractive Keratectomy and Laser In Situ Keratomileusis in Rabbits

BACKGROUND

After 193 nm excimer laser photorefractive keratectomy (PRK) for myopia, superficial opacities in the ablation zone and regression of refractive results can occur. Clinical studies have emphasized that corneal clarity and early refractive stability can be achieved with laser in situ keratomileusis (LASIK). We present clinical and histological results that compare PRK and LASIK for the treatment of myopia in rabbits.

MATERIALS AND METHODS

We treated 12 New Zealand white rabbits with PRK and 12 with LASIK using a 193-nm excimer laser (Aesculap Meditec). In both techniques, the identical excimer software and ablation parameters of -10 D treatment depth were used. Six months after surgery, all eyes were removed and prepared for light, fluoresence and transmission electron microscopy.

RESULTS

At the time of enucleation, nine eyes in the PRK group had a moderate to high degree of haze (grade 2 to 3), whereas after LASIK, all corneas showed an almost clear interface in the ablation zone. Correspondingly, all histological investigations after LASIK showed a regular stromal architecture, in contrast to the obvious anteri or stromal disorganization after PRK.

CONCLUSION

The preserved integrity of the superficial corneal layers after LASIK ensures quick wound healing with minimal tissue proliferation, resulting in a transparent corneal interface. This technique appears especially suitable for correcting high myopia.

Ocular toxicity and cancer chemotherapy. A review

BACKGROUND

Systemic anticancer therapies can produce acute and chronic organ damage, but the eye is usually considered a protected site. Nonetheless, the oculo-visual system has a potentially high degree of sensitivity to toxic substances. Ocular toxicity induced by cancer chemotherapy includes a broad spectrum of disorders, reflecting the unique anatomic, physiologic, and biochemical features of this essential organ.

METHODS

A review of the literature regarding the ocular toxicity of chemotherapeutic agents, hormonal agents, biologic agents, and high dose chemotherapy with allogeneic and autologous bone marrow transplantation was conducted.

RESULTS

Ocular toxicity induced by anticancer chemotherapy is not uncommon. The development of more aggressive regimens as well as new agents and combination chemotherapies have resulted in a significant increase of reported cases of chemotherapy-induced ocular side effects. In most instances, the mechanisms of ocular toxicity continue to be poorly understood.

CONCLUSIONS

Ocular toxicities induced by chemotherapeutic agents are generally not preventable; therefore, clinicians must be aware of potential vision-threatening complications. Prompt consultation with an ophthalmologist can lead to early detection, proper diagnosis, and appropriate therapeutic measures. Dose reduction or discontinuation of incriminated drugs may help in reducing the severity and the duration of side effects.

Long term results of intraoperative mitomycin C in the treatment of recurrent pterygium

AIM

The study was designed to evaluate the long term results of intraoperative mitomycin C in patients with one recurrence of pterygium.

METHODS

In 45 white patients with one recurrence of pterygium the 'bare sclera technique' was performed and a sterile sponge soaked in a 0.2 mg/ml (0.02%) mitomycin C solution was placed intraoperatively on the sclera for 3 minutes. The control group underwent surgical excision only. Recurrences were analysed by the chi 2 test and the method of Kaplan-Meier (life table analysis); the difference between survival curves was tested by the log rank test. The chi 2 test with Yates's correction or Fisher's exact test were used to analyse the difference in complications and side effects between the two groups.

RESULTS

After a mean postoperative follow up of 34.55 (SD 13.70) months, 6 recurrences (12.5%) were observed in the mitomycin C treated patients and 16 (35.6%) in the control patients (p = 0.027). The 24 and 48 month life table success rates were 89% and 83% in the mitomycin C treated group and 66% and 63% in the control group, respectively (p = 0.022). No severe side effects appeared during follow up. Superficial punctate keratitis appeared in the early postoperative period in only seven mitomycin C treated eyes (15.5%) (p = 0.018).

CONCLUSION

This study confirms the efficacy of intraoperative mitomycin C in improving the success rate after recurrent pterygium surgical excision.

Intraoperative application of topical mitomycin C for pterygium surgery

BACKGROUND

Postoperative recurrence of pterygium occurs in many patients. The authors studied the recurrence rate of pterygium after administration of a single intraoperative dosage of topcial mitomycin C at the completion of pterygium excision.

METHODS AND PATIENTS

Eighty-one patients underwent excision of the pterygium, leaving the sclera bare. The first 60 patients were randomized into two treatment groups of 30 patients each. Their remaining 21 patients were offered mitomycin C. Group 1 included 49 patients (30 randomized and 19 of the remaining 21 patients) who received an intraoperative application of 0.02% (0.2 mg/ml) mitomycin C for 5 minutes, and group 2 included 32 patients (30 randomized and 2 of the remaining 21 patients) who received NaCl 0.9% instead of mitomycin C. Patients were followed from 12 to 28 months in a masked manner.

RESULTS

The pterygium recurred in 2 (4%) of 49 patients in group 1 and in 15 (46.7%) of the 32 patients in group 2 (P = 0.0001). A delay of epithelialization for 5 and 10 weeks occurred in two patients in group 2 and granuloma manifested in one patient in group 1.

CONCLUSION

This study indicates that intraoperative administration of a single dosage of 0.02% mitomycin C is an effective treatment for prevention of recurrence of pterygium.

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

We used an animal model of restrictive strabismus analogous to the fat adherence syndrome in humans to test the efficacy of topical intraoperative mitomycin-C (MMC) in preventing the development of restrictive scar tissue. A cicatricial adhesion was created between the inferior rectus muscle and the inferior orbital rim of each eye in eight rabbits, and passive forced ductions were quantitatively measured with a spring scale. Eight eyes were treated intraoperatively with topical MMC 0.5 mg/mL, the other eight with sterile water. Passive forced ductions were again measured 4 weeks postoperatively and representative orbits were exenterated for histopathologic examination. Significant restriction of motility was produced in six of the eight control eyes. Though prophylactic treatment with MMC may have been beneficial in some cases, on average, the restriction developing in these eyes did not significantly differ from that in the control eyes. In addition, longer exposure times to MMC led to marked orbital inflammation and severe restriction of ocular motility. Finally, histopathologic evaluation of the orbits of the MMC-treated eyes revealed marked fibrosis of perimuscular connective tissues. Although MMC may have a role in the management of fat adherence syndrome, further study is needed to establish safe and efficacious methods of delivery.

Long-term results using adjunctive mitomycin C in optic nerve sheath decompression for pseudotumor cerebri

PURPOSE

Up to 35% of patients undergoing optic nerve sheath decompression (ONSD) for pseudotumor cerebri who show initial improvement in visual function later show deterioration in visual field and acuity. Although repeat surgery can result in subsequent visual improvement, these procedures are technically difficult because of scarring and fibrosis. Attempting to improve the long-term success of ONSD, the authors sought to analyze the long-term success of ONSD by pretreating optic nerve sheaths with mitomycin C before incision.

METHODS

Using a standard transconjunctival medial orbitotomy, optic nerve sheaths were exposed and treated for 5 minutes with mitomycin C (0.5 mg/ml)-soaked neurosurgical cottonoids before incision.

RESULTS

Both eyes undergoing repeat ONSD with adjunctive mitomycin C had initial improvement and stable visual function for follow-up of more than 3 years. Four eyes that underwent primary ONSD all initially showed improvement in visual field. Three eyes with large cysts or fistulas remained stable. Another eye had gradual decline in visual function. Repeat ONSD in this eye showed no orbital scarring, and lysis of adhesions between dura-arachnoid and optic nerve resulted in improved, stable visual function for 31 months of follow-up.

CONCLUSION

Mitomycin C appears to be a safe adjunct to ONSD in a series of six patients followed between 20 and 37 months. Fistulization and cyst formation are associated with improved visual function. Closure of cysts and fistulas may result in worsening visual function due to intersheath adhesions. Repeat surgery shows significantly less orbital scarring and allows for easier and successful repeat surgery. Adjunctive mitomycin C leads to less orbital scarring after ONSD, allowing for easier repeat surgery.

Single intraoperative application versus postoperative mitomycin C eye drops in pterygium surgery

PURPOSE

To determine the minimum effective dosage, most effective route of administration and long-term effects of mitomycin C for prevention of recurrence after pterygium surgery.

METHODS

In a prospective, masked study, 227 patients undergoing surgery for primary pterygia were assigned randomly to five groups: group 1 received a single intraoperative application of 0.2 mg/ml mitomycin C for 3 minutes; group 2 received a single intraoperative application of 0.4 mg/ml mitomycin C for 3 minutes; group 3 received mitomycin C eye drops 0.2 mg/ml three times daily for 7 days; group 4 received mitomycin C eye drops 0.4 mg/ml three times daily for 14 days; group 5 acted as a control (surgery alone).

RESULTS

After a mean follow-up time of 28 months, recurrence rates of 6.66%, 4.08%, 4.26%, 4.44%, and 29.27%, respectively, were observed. Statistical analysis showed significant differences between groups receiving mitomycin C and the control (P < or = 0.001). There was no statistical difference among treated groups (P > or = 0.0681). No complications of therapy were observed.

CONCLUSION

These results support the efficacy and relative safety of a single, low-concentration, intraoperative application of mitomycin C in pterygium surgery together with the use of a conjunctival flap, avoiding excessive cauterization of the sclera and leaving bare sclera.

A randomized trial comparing mitomycin C and conjunctival autograft after excision of primary pterygium

PURPOSE

To determine the rate of recurrence and complications after bare sclera excision of primary pterygia followed by low-dose mitomycin C (0.2 mg/ml twice daily for five days), placebo (balanced saline solution), or conjunctival autograft.

METHODS

We performed a prospective, double-masked clinical trial of 64 patients (60 Hispanic) randomly assigned to a treatment group. Twenty-four patients received mitomycin C, 23 conjunctival autograft, and 17 placebo. Recurrence was defined as fibrovascular tissue over the corneoscleral limbus onto clear cornea in the area of previous pterygium excision.

RESULTS

The recurrence rate after mitomycin C and conjunctival autograft was 38% and 39% of eyes, respectively, after mean follow-up (in recurrence-free patients) of 12.3 and 13.5 months, respectively. The recurrence rate after placebo treatment was significantly higher (P = .002), 88%, after mean follow-up (in recurrence-free patients) of 9.3 months. Increasing age was associated with significantly fewer recurrences (P = .006) after controlling for pterygium type (atrophic, noninflamed, or inflamed) and treatment group. The mean time to recurrence varied from 3.7 to 4.8 months; only 6% of recurrences were noted after the sixth postoperative month. Major complications included symblepharon (two), loose autograft (one), and pyogenic granuloma (two). No group had significantly more complications.

CONCLUSIONS

Conjunctival autograft and low-dose topical mitomycin C are equally effective as adjunctive treatment after excision of primary pterygia in this young, southern California, predominantly Hispanic population. Both methods have significantly lower rates of recurrence than bare sclera excision alone, and neither is associated with severe complications after one year of follow-up. Increasing patient age is associated with significantly less risk of recurrence.

Hyperbaric oxygen therapy for beta-radiation-induced scleral necrosis

BACKGROUND

Beta-radiation has been used since 1950 as a postoperative measure to reduce the recurrence of pterygia. Scleral necrosis has been a major complication after radiotherapy that has led to perforation of the globe, endophthalmitis, and visual loss in some cases.

METHOD

A patient is presented in whom scleral necrosis developed 25 days after a pterygiectomy with bare sclera technique followed by 3000 cGy in 3 weekly, divided doses of strontium 90. After a conjunctival graft failure, the patient was treated with hyperbaric oxygen therapy.

RESULTS

The sclera revascularized and returned to nearly normal thickness after 14 sessions of hyperbaric oxygen therapy.

CONCLUSION

Hyperbaric oxygen therapy may be an effective treatment for acute scleral necrosis after postoperative beta-radiation.

Success rate and complications of intraoperative 0.2 mg/ml mitomycin C in trabeculectomy surgery

Adjunctive chemotherapy with Mitomycin C (MMC) has been used in an attempt to modulate the wound healing response in glaucoma filtration surgery. A consecutive series of 20 eyes from 18 patients undergoing trabeculectomy with MMC intraoperatively was studied. Sixteen cases were considered high risk regarding surgical success and 4 patients with low tension glaucoma (LTG) required lower intraocular pressure (IOP) to prevent further visual field loss. Surgical technique involved the use of a limbal-based conjunctival flap and MMC 0.2 mg/ml applied via a sponge (under the scleral flap) to both scleral and conjunctival surfaces for 5 minutes. The mean follow-up period was 12.7 months (range 3-24). There were 17 successful eyes. Of these, 14 are high pressure glaucoma eyes with a mean pre-operative IOP of 30.9 +/- 10.9 mmHg and a mean postoperative IOP of 15.3 +/- 5.2 mmHg (p = 0.001). The remainder of the successful cases include 4 patients with LTG with a mean preoperative IOP of 17.8 +/- 0.5 mmHg and a mean postoperative IOP of 6.8 +/- 0.7 mmHg (p = 0.001). Serious complications included chronic repeated bleb leaks (n = 2) and scleral necrosis (n = 2). There was one case of hypotonous maculopathy. These results are comparable with those of other studies. Despite a relatively low dose of MMC serious side-effects were encountered. Management of these complications is described, and how these effects may be prevented by altering scleral exposure to MMC. In addition a possible explanation for the serious side-effects of MMC-treated trabeculectomies is presented.

Prospective trial of intraoperative mitomycin C in the treatment of primary pterygium

AIMS

A prospective, randomised, double blind, placebo controlled study of intraoperative mitomycin C as adjunctive treatment of primary pterygium was conducted.

METHODS

A total of 66 eyes of 54 patients with primary pterygium were treated with excision, with or without a single intraoperative application of mitomycin C (0.1 mg/ml for 5 minutes) to evaluate the efficacy and toxicity of this adjunctive treatment. The mean follow up was 14.1 months (range 12-23 months).

RESULTS

Of the 36 eyes that underwent simple excision, 14 (38.8%) exhibited recurrences whereas only one of 30 eyes (3.33%) treated with excision and intraoperative application of mitomycin C had recurrence (p = 0.0006). Neither serious ocular complications nor systemic toxicity were noted in the mitomycin C treated group.

CONCLUSION

Intraoperative mitomycin C appears to be an effective and safe adjunctive treatment of primary pterygium.