Efficacy of Amniotic Membrane Transplantation in Infectious Corneal Perforations of Various Sizes

Thatte S and Singh OS

Published on: 2021-02-19

Abstract

Aim: To evaluate the efficacy of Amniotic membrane transplantation in infectious corneal perforations of various sizes.

Purpose: To determine if single / multilayer amniotic membrane transplantation (AMT) is beneficial in the management of infective corneal perforations, particularly to assess effectivity with various sizes of perforation and its limitations.

Material: 62 eyes of 62 patients with refractory infective keratitis with corneal perforations of various sizes were examined and grouped according to the size of perforation. These underwent single or multilayer amniotic membrane transplantation as per size of perforation. Minimum follow-up was up to 6 months. Success of AMT was supervised to observe improvement in infection, inflammation and healing of perforation.

Result: Acceptable response was seen in smaller perforation less than 2mm with single layer and 2 to 6 mm of perforations with multilayer AMT. Satisfactory results were seen in 75.8%, intermediate results in 24.2%, requiring minor subsequent secondary procedure. Desired tectonic result with complete healing of corneal perforation was seen in 92.85% , but optical results with visual gain was attained only in 71.4% patients , rest 21.4% cases show no visual gain as these cases healed with central leucomatous corneal opacity obscuring the visual axis , requiring subsequent optical penetrating keratoplasty.

Conclusion: AMT is advantageous to resolve tissue degradation, enduring inflammation and for restoration of perforated corneal surface in infectious corneal perforations. Less than 2mm to 6 mm size of perforations attains complete healing. Where as in more than 6 mm of perforation, Amniotic membrane is a useful as a temporary tool to maintain integrity of eyeball.

Keywords

Corneal perforation; Infective etiology; Amniotic membrane transplantation; satisfactory results; Tectonic support

Introduction

Infectious keratitis is one of the leading causes of ‘preventable’ blindness globally and in India [1]. Which has vision-threatening consequences and one of the sequelae is corneal perforation [2]. Corneal perforation is always a medical emergency requiring prompt intervention [3-11]. The management of corneal perforation depends on the etiology, size, corneal infiltration, location of perforation, and status of ocular co-morbidities [12, 13]. Management is critical to maintain or restore the integrity of the eye ball, to prevent ingress of microorganisms and to restrict tissue destruction and scarring, [14] which can be achieved surgically. Surgical management of corneal perforation include tissue adhesives, bandage contact lenses (BCL), penetrating or patch corneal grafts, tenon’s graft or conjunctival flaps and amniotic membrane [15]. Tissue adhesives, BCL and conjunctival flaps are useful in smaller perforations as a temporary measure to obviating the need for penetrating keratoplasty (PK) within a few days, as they do not provide with new collagen to fill the corneal defect and stabilize the globe [16,17]. Tenon’s patch graft is effective for peripheral small perforations of less than 3mm, [18] Penetrating keratoplasty (PK) or corneal patch grafts are the popular option in removing infected part and replacing with healthy tissue to provide globe integrity. These techniques require immediate donor corneal tissue and have known complications like secondary glaucoma, uveitis, and reinfection and graft failure as they are performed in an inflamed and infected eye [19]. Regrettably, these procedures maintain only structural integrity and solve tectonic problem, but not the ongoing infection and inflammation. Therefore, we require a procedure which provides new filling in collagen to reform corneal structures by providing tectonic support and at the same time reduces ongoing infection and inflammation. The amniotic membrane (AM) provides a good alternative to achieve these goals. It has properties of promoting epithelialization, healing, inhibiting inflammation and angiogenesis, reducing fibrosis and scarring [20]. It offers potential to use as a substrate with no graft rejection, thus can be used as a treatment for corneal perforation by restoring corneal stromal thickness so that emergency penetrating keratoplasty can be avoided. Even if corneal transplantation is needed after complete healing with amniotic membrane transplantation (AMT), the success rate is enhanced [21, 22]. In this prospective study AMT in corneal perforations of various sizes of refractory infective keratitis has been attempted to understand the efficiencies and limitations associated with amniotic membrane transplantation.

Methodology

This prospective, interventional study was conducted December 2015 to September 2019. The work started after the review and approval of protocol of study by Institutional Ethics and Research committee. (Research No: SAIMS/IEC/2019/45) (Reg. No:ECR/748/Inst/MP2015) Patients with corneal perforation of different sizes were counted in the study after taking written informed consent from the patient. The data was collected and recorded. Patients included in the study were of any age and sex with infective corneal perforation who consented for study and had no communication barriers.

Patients not included in the study were:

  • Patients not consenting for the study.
  • Ocular comorbidities other than the indication for the planned ophthalmic surgery.
  • Patients with non-infective ulcers and perforations,
  • Involvement of posterior segment, defective perception of light.
  • Patients with systemic diseases\syndromes associated with dry eye

62 eyes of 62 patients with refractory infective keratitis with corneal perforations of various sizes were underwent a detailed history to record etiology , thorough slit-lamp examination to note down size, site of perforation, surrounding infiltration and status of anterior segment. Microbial investigations (staining with Gram’s and KOH along with culture and sensitivity) were carried out to identify the organism and antimicrobials started accordingly. B-scan ultrasonography was performed to identify involvement of posterior segment. A detailed systemic examination was executed to understand systemic conditions delaying the healing process and were managed accordingly. Selected patients were grouped accordingly size of perforation in to small (up to 2 mm), moderate (2 to 4 mm) and large perforation (4 to 6 mm). A clinical photograph was taken for record in each case.

Surgical Technique

Subconjunctival or peribulbar anesthesia was given very carefully avoiding spontaneous extrusion of intraocular contents in mild and moderate perforations. General anesthesia was preferred in large perforations with surrounding scleral necrosis, children or uncooperative patients. If infiltration was extending up to limbus, a focal peritomy was performed. Then necrotic tissue was debrided surrounding the perforation. Care was taken to remove the pseudo cornea/ necrotic material over the perforation at the end of debridement to prevent collapse of anterior chamber. In small perforations up to 2 mm, single sheet of AM with epithelial side up was spread over the perforation up to surrounding healthy tissue. It was secured with continuous 10-0 monofilament nylon suture. In moderate corneal perforations of 2 to 4 mm and large perforations 4 to 6 mm multilayer AM in the form of folded sheet with 4 to 5 layers, was placed covering perforation and beyond and secured to the healthy tissue with interrupted / continuous 10-0 nylon suture. This multilayer was covered with a larger single sheet of AM. After securing AM in place prolapsed iris was reposited back with iris repositor from the side port, synechiae were separated to prevent formation of adherent leucoma. Hypopyon was washed through the side port and as per sensitivity report appropriate intracameral antibiotic or antifungal was injected into anterior chamber. Reformation of anterior chamber was performed with air. BCL was placed over the cornea to secure AM in place and prevent irritation from corneal sutures. Post-operatively antimicrobial, cycloplegics, ocular hypotensive and lubricating drops were prescribed along with systemic supportive therapy. Follow-ups were done weekly for 1 month, biweekly till 3 months and monthly till 6 months. Effectiveness of AM was supervised on basis of improvement in symptoms, healing of the perforation, formation of anterior chamber. On these basis, outcome of procedure was described as satisfactory, intermediate and failure (Table 1).

Table 1: Definition of outcomes after AMT in corneal perforations.

Outcome

 Definition Of Outcome

Satisfactory

Healed and stable surface
Achieving anterior chamber depth,
Complete symptomatic relief.

Intermediate

Healed corneal surface
Requiring any subsequent intervention after surgery (hypopyon wash, air injection in AC, re-grafting)

Failure

Not healed corneal surface, or
Progressive thinning
No improvement in symptoms.

Results

70 patients of infective corneal perforation of various sizes were included in the study.

Table 2: Age and gender distribution.

Age/Gender

No Of Cases

Age

42.2±15.1

Male: Female

10:04

Table 3: Classification of Corneal perforations.

Type Of Perforation

Size Of Perforation

No Of Patients

Small Perforation

<2mm

12(17.14%)

Moderate Perforation

2-4mm

32(45.71%)

Large Perforation

4-6 mm

18(25.71%)

Table 3 classifies perforations in various sizes as shown. Size of corneal perforation ranged from 1 to7 mm.

Table 4: Height of hypopyon.

Hypopyon

No Of Cases

Absent

50 (71.42%)

<1mm

5(7.14%)

1-2mm

10(1428%)

>2mm

5(7.14%)

All patients had symptoms of redness, pain, watering and foreign body sensation (FBS). Hypopyon was present in total 20 (28.57 %) cases where 05 cases (7.14%) had hypopyon of <1mm, 10 cases (14.28%) had hypopyon ranging between 1-2mm and 05 cases (7.14%) had hypopyon of >2mm (Table 4).

(Pearson Chi-Square = 11.077, DF = 6, P-Value = 0.086 Non Significant Association)

Table 5: Type of perforation and Etiology.

Type Of Perforation

Bacterial

Fungal

No Growth

Mild perforation <2mm

7(23.33%)

3(21.42%)

2(11.11%)

Moderate perforation 2-4mm

14(46.66%)

7(50%)

11(61.11%)

Large perforation 4-6mm

09(30%)

4(28.57%)

5(27.77%)

Total

30( 48.38% )

14 ( 22.58% )

18 ( 29.03 % )

Pearson Chi-Square = 11.077, DF = 6, P-Value = 0.086 Non Significant Association

As shown in table 5, on microbiological tests most common etiology was bacterial infection in 30 (48.38%) cases and fungal growth was seen in 14(22.58%) . In remaining 18 (29.03%) cases no growth of organism was observed. In bacterial etiology commonest organism found was staphylococcus group.

Table 6: Bacterial isolates and their frequency.

Bacterial Species

Frequency Of Isolates

%

Streptococcus pneumonia

13

43.34%

Pseudomonas sp

5

16.66%

Staph Epidermidis

3

10%

Cornybacterium Xerosis

4

13.33%

Others

5

16.66%

TOTAL

30

100%

Considering the bacterial isolates streptococcus pneumoniae(43.34%) was the most common bacterial species followed by pseudomonas sp(16.67%). Others isolated were Staph. Epidermidis (10%) and corny bacterium xerosis (13.33%) as depicted in table 6.

Table 7: Fungal isolates and frequency.

Fungal Species

Frequency Of Isolates

%

Fusarium

10

71.50%

Aspergillus

2

14.20%

Candida

1

7%

Others

1

7%

TOTAL

14

100%

Table 7 Shows fungal isolates with Fusarium(71.5%) and Aspergillus(14.2%) as the most common fungi followed by Candida(7%) and some others(7%).

(Pearson Chi-Square = 70.000, DF = 3, P-Value = 0.000 Significant association)

Table 8: Type/Size of perforation and type of procedure of AMT.

Type Of Perforaton

Size Of Perforation

No Of Patients

Amt

Small Perforation

1 – 2 mm

12(17.14%)

Single layer

Moderate Perforation

2– 4 mm

32(45.71%)

Multiple layer

Large Perforation

4-6

 mm

18(25.71%)

Multiple layer

Pearson Chi-Square = 70.000, DF = 3, P-Value = 0.000 Significant association Single layer AMT was done in total 12 cases, 12 cases of small perforations (<2 mm) (Figure 1a, b, c).

Figure 1a: Small Perforation<2mm.

Figure 1b: Single layer AMT.

Figure 1c: Healed corneal perforation after 1 month.

Multilayer technique was done in 50 cases, all 32 cases of moderate perforation (2-4mm) (Figure 2 a, b, c)

Figure 2a: Moderate perforation 3mm.

Figure 2b: Multilayer AMT.

Figure 2c: Healed perforation after 2 months.

18 cases of large corneal perforation (4-6 mm) (Figure 3, a, b, c, d)

Figure 3a: Large perforation.

Figure 3b: Large perforation on slit lamp.

Figure 3c: Multilayer AM in place.

Figure 3d: Healed perforation.

Table 9: Improvement in Symptoms on follow up.

Symptoms

Pre-op (%)

Follow-up days (%)

1 week

1 month

3 month

6 month

Pain

65 (92.85%)

27

(38.57%)

7

 (10%)

9 (12.85%)

0

Lid oedema

59 (84.28%)

14

(20%)

0

0

0

Watering

65 (92.85%)

32

(45.71%)

7 (10%)

0

0

Redness

70 (100%)

37

(52.85%)

5 (7.14%)

0

0

Photophobia

63 (90%)

51

(72.85%)

9

(12.85%)

0

0

Foreign body sensation

67 (95.7%)

24

(34.28%)

14

(20%)

4 (5.71%)

0

Discharge

20 (28.57%)

8 (11.42%)

0

0

0

In post-operative period rapid descent of symptoms was observed. There was drastic improvement in pain, lid edema, foreign body sensation and discharge in the first week except in 5 (7.1%) cases with fungal keratitis. These cases failed to respond to AMT and between 1st to 4th weeks and were planned for tectonic keratoplasty to save the structural integrity. Out of rest 65(92.8%) patients symptoms were improved by 1 month in 46 cases (70.7%), and by the end of 3 months perforation healed completely in 65 without any symptoms.

Table 10: Size of perforation and Visual acuity pre and post AMT.

Size Of Peforation

Category Number (%)

Pre Amt Visual Acuity

Post Amt Visual Acuity

<2mm

8(17.4%)

6/60-6/36

6/12-6/9

2mm - 4mm

30(65.2%)

6/60- HM

6/9-6/24

4mm - 6mm

8(17.4%)

Fc3ft-HM+

6/18 -6/36

TOTAL

46

   

Table 11: Post-operative complications and management.

Complications

<2mm

2-4mm

4-6mm

Total

%

Treatment

Shallow anterior chamber

0

1`

4

5

8.06

Air injection in anterior chamber

Sub – graft haemorrhage

0

2

4

6

9.67

Strict observation

Graft retraction

0

1

1

2

3.2

Repeat AMT

Graft melting

0

1

1

2

4.8

Tectonic keratoplasty

Hypopyon

0

0

3

3

29.03

AC wash with AMP-B and Moxifloxacin

Total

18

Complications as illustrated in table 11 were mild to moderate. Shallow anterior chamber was seen in 5(8.06%) cases which were succeeded with air injection in anterior chamber. Sub-graft haemorrhage was present in 6(9.07%) cases which resolved spontaneously. 2 cases had graft retraction due to loosening of sutures which was treated with repeat AMT. Reformation of hypopyon was recorded in 3(29.03%) cases, they were treated with anterior chamber wash and intracameral moxifloxacin and amphotericin-B respectively as per etiology and sensitivity report. Satisfactory results were seen in 47 of 62 eyes (75.8%), intermediate results which requiring minor subsequent secondary procedure seen in 15 cases (24.2%).

Table 12: Size of perforation and post AMT outcomes.

Size Of Perforation

Satisfactoy

Intermediate

Failure

<2mm ( 12 )

12(100%)

-

-

2mm-4mm

30(93.75%)

2(6.25%)

-

-32

4mm-6mm

5(27.77%)

13(72.22%)

-

-18

Total

47(75.80%)

15(24.2%)

0

Desired tectonic results were seen in all 62 cases, of which 16 cases (25.8%) developed central leucomatous corneal opacity obscuring the visual axis subsequent optical penetrating keratoplasty was recommended (Table 12).

Discussion

Corneal perforations require emergency management in form of immediate tectonic support, to maintain integrity of globe and to prevent further vision threatening complications. Keratoplasty is the treatment of choice to replace collagen. However limitation of availability of good quality donor corneas especially in developing countries, high chances of recurrence of infection because of active disease, may failed to achieve desired goal. Further keratoplasty provides only tectonic support but does not aid in resolving tissue degradation and ongoing inflammation [18]. Therefore chances of graft failure in these situation is quite high, and subsequent graft performed for optical purpose also has poor success rate. Reconstruction of this perforated surface require filling in new collagen which can be attained by Amniotic Membrane [23-26], AM promotes healing because of its properties of promoting re-epithelization, preventing neovascularization , reducing scarring , inflammation, and avoiding potential allograft rejection. These properties help AM to heal infectious corneal perforations. If postoperative optical keratoplasty is required in these healed corneal opacities, without active infection, results are satisfactory [21, 22]. Previous studies on effectivity of AM in infectious keratitis have included all stages of keratitis, corneal thinning, descemetocoele and perforations. Studies on corneal perforations included various etiology infective and inflammatory. Our study was very specific limited only to infective corneal perforations.

In our study was 62 corneal perforations with infective pathology were included, while Chen and Kim had sample size of 23 and 21 respectively including different etiologies. Better inference could be achieved in our series as it was a large series specific for infective etiology [27-29]. Common organisms responsible for infectious keratitis were streptococcus pneumonia amongst bacteria and fusarium for fungal keratitis. Other studies also noticed staphylococcus, Streptococcus, Acanthamoeba and fusarium as a causative organism [18,27,28]. We included patients with perforation size up to 6mm, while other studies of Chen and Kim encompassed perforation size of up to 3mm. surgical techniques were different in various sizes of perforations in present study. Perforations <2mm single sheet of AM was used. Single layer of AM was placed and analyzed in our study. In cases with perforations of more than 2 to 6 mm multiple layer of AM is secured to cover the perforation, this variation in technique was not described by other studies as they included perforation less than 3 mm. Multilayer AM was used in different studies to restore corneal thickness in various sizes of corneal perforations[27,28]. Many other studies exhibited effectivity of multilayer AM over single layer procedure [30-32]. Our study observed effectivity of single layer of AM for smaller perforations up to 2 mm and multilayer AM in mild (2-4mm) and moderate (4-6mm) size of corneal perforations. Whereas other studies including Hanada [29] experimented success of AM in corneal perforations only from 0.5 to 3 mm. Complications in the form of hypopyon was seen in 4.8% of cases, and succeeded by intracameral wash with appropriate antifingal and antibiotics after performing culture/ sensitivity of the sample. Study done by Chan [27] presented persistent infection in 2(8.7%), while in Kim [28] no complications were seen. Shallow anterior chamber was realized postoperatively in 5 cases with perforation ranging from 2mm to 6 mm and reformation of anterior chamber could be achieved by air injection into anterior chamber, while perforation less than 2mm not displayed this complication similar to other studies with perforation upto 3mm. Properties of amniotic membrane avails less complications. In Chen [27] study, 4 of 23 cases faced AM melting and graft failure requiring therapeutic PK in 3 eyes and delayed healing with vascularization in the rest 19 cases. Kim [28] found success in all cases without recurrence of infection or rejection. In our study very few complications were seen in the form of shallow anterior chamber, sub-graft haemorrhage, hypopyon and graft retraction which were managed successfully. Only 2 cases (3.2%) in large perforation had graft melting due to reinfection and needed tectonic keratoplasty. Success rate of 100 % reached in mild perforation (up to 2mm), in moderate (2 to 4 mm) and large perforation (4 to 6 mm) group satisfactory results were 93% and 27% respectively, after secondary intervention rest all cases achieved intermediate results. While other reported success rate of 82% in less than 3 mm perforation.[27,29] In present study complete healing in the form of satisfactory results was seen in 47(75.8%). Intermediate results in the form of complete healing after minor secondary procedures was distinguished in 15 of 62 cases (24.2%) [27]. Showed 73.91% success rate, [28] found complete healing successfully in all cases [29]. Also noted high success rates (73–93%). Heiligenhaus, series with seven patients of herpes simplex virus or varicella zoster-induced severe ulcerative keratitis, 5 of 7 eyes healed after first AMT [30] In our study 46(74.19%) cases showed significant improvement in best-corrected visual acuity emphasizing the healing properties of AMT. 16 cases had dense leucomatous corneal opacities obscuring pupillary area therefore unsuccessful to show improved visual outcome [27]. preserved useful vision after AMT in cases of fungal keratitis in 52.2% eyes [28] reported 21 cases of successful AMT in infectious keratitis , in which visual acuity increased except for 5 cases because of irreversible corneal opacity. In small perforations of <=2mm, results were very encouraging 100% success rate while other studies detected success rate between 82 to 100 % [27,28]. In cases of perforations between more than 2 to 6 mm we could attained efficacy of AMT which was not tried in any other studies. Realizing efficacy of AM in larger size (more than 3mm) of perforation was experimented first time, creating this study unique. Considering the site and size of perforation, AMT has proved to be very effective technique for refractory infective corneal perforations in accomplishing satisfactory results.

Conflicts Of Interest

There were no conflicts of interest.

Conclusion

This study evaluates usefulness of AMT in corneal perforations of various sizes of refractory infective keratitis to understand the efficiencies and limitations. AMT may be used to resolve tissue degradation, enduring inflammation and for restoration of perforated surface in healing of infectious corneal perforations of 2 to 6 mm size.

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