FP1233 : Therapeutic Penetrating Keratoplasty:penetrating keratoplasty: Indications and Surgical Outcomeoutcome

Dr. Sudesh Kumar Arya, A06388, Dr.
Meenakshi Sindhu, Dr. Amit Raj, Dr. Ravi Kant
Bamotra

ABSTRACT

Authors: Sudesh Kumar arya, Meenakshi Sindhu, Amit Raj, Ravi Bamotra

Aim: To find out the indications and outcome of therapeutic keratoplasty in a tertiary eye hospital, in last 15 years.

Methods:

A retrospective data of patients who underwent therapeutic penetrating keratoplasty from 1999 to 2014 was reviewed. Various parameters included in the study were demographic profile of patients, indications for surgery, microbiological status, donor tissue details and complications of the surgery. The results were assessed in terms of eradication of disease, anatomic success, graft clarity, visual acuity, and development of complications.

Results:

A total of 358 eyes of 350 patients were studied of which 66% were male. The mean age of patients was 48.4±15.7 years. The main indications for surgery were fungal keratitis (38%) followed by mixed (Polymicrobial?) sloughing ulcers (32%). 10% of ulcers was perforated. 33% eyes were positive for organisms of which 18% showed pure fungus and 10% showed pure bacteria. The commonest fungus and bacteria isolated were Aspergillus and pseudomonas, respectively. The anatomical success and eradication of infection was achieved in 85.5% eyes. In the postoperative course, 44.4% developed secondary glaucoma 7.8% eyes required re-surgery. Overall functional success with a visual acuity above 3/60 was 9.4%.? Fungal keratitis had a higher anatomical success, and graft clarity and less complication rates compared to bacterial or mixed infection.(contradicts most published literature)

Conclusion:

Therapeutic keratoplasty remains a mainstay procedure to preserve the eye in severe corneal infections. There is a high incidence of postoperative glaucoma and graft failure in such a surgery. Fungal keratitis has a better outcome than bacterial keratitis.

 INTRODUCTION

Corneal ulcer is the major cause of visual impairment and blindness in developing countries.¹ Lack of accessibility to healthcare facilities, delayed treatment, and resistance to antimicrobial therapy lead to worsening of ulcer and even perforation  which finally require a therapeutic penetrating keratoplasty (TPK). The procedure leads to replacement of infected tissue with a normal sterile donor corneal button. ² This an emergency procedure and its primary goal remain the eradication of infected tissue reestablishment of globe integrity. The visual rehabilitation is of secondary consideration which may or may not be achieved.

TPK constitutes a significant proportion of keratoplasty performed in Asian and other developing countries.² TPK carries a risk of recurrence of infection and also has a higher risk of graft rejection and graft failure compared to optical keratoplasty. The postoperative complications such as uveitis, glaucoma, synechia, and cataract are higher as compare to optical penetrating keratoplasty. ³ The study is done to find out the outcome of TPK. This will also be helpful in providing the information for further prospective studies. Also, we will be able to identify the risk factors for the graft failure changes that need to be done to improve the outcome.

MOTHODS

A retrospective data of patients who underwent therapeutic penetrating keratoplasty from 1999 to 2014 was reviewed. Various parameters included in the study were demographic profile of patients, indications for surgery, microbiological status, donor tissue details and complications of the surgery. The results were assessed in terms of eradication of disease, anatomic success, graft clarity, visual acuity, and development of complications. Comparison was made between the outcome of bacterial and fungal ulcer undergoing TPK. Cases which had follow-up of less than 2 months were not analyzed for outcome. In those cases that had undergone TPK more than once, only the first TPK was considered for outcome assessment.

SURGICAL TECHNIQUE AND POSTOPERATIVE MANAGEMENT

The TPK was performed under general anesthesia in all patients after giving intravenous 20% mannitol 5ml/kg body weight half hour before surgery. The criteria for quality of the donor tissue may not be as stringent as for optical penetrating keratoplasty. So, even very old, aged cornea or with low endothelial cell count were used if better tissues were not available. In all cases, the donor size was exceeded by 0.5 mm the recipient size. The recipient cornea was incised using corneal trephine. Care was taken to avoid pressure on the globe to avoid dreadful complications. In case of a large perforation and sloughing ulcer, freehand dissection of the host bed was performed, after initial marking with a trephine. The entire infiltrated area along with 1 mm of healthy corneal tissue was removed in most of the cases except when the whole of the cornea was infiltrated. The excised corneal specimen was sent for microbial investigations and histopathological examination.

Purulent material was irrigated from the anterior chamber. Inflammatory membranes over the iris and pupil were mechanically removed with forceps. Anterior and posterior synechiae were released. One or two iridectomies were performed to prevent pupillary block glaucoma. Cataract extraction was done when there was infection extending to the lens,(?even Fungus) presence of white swollen lens with probability of pupillary block, iatrogenic trauma to lens, or when lens was extruded itself. Intravitreal injection of anti­microbial and/or anterior vitrectomy was done in cases of suspected endophthalmitis and spontaneous lens extrusion. 10-0 Nylon interrupted sutures were used to close the graft host junction.

Postoperatively, the duration of antimicrobial treatment was titrated based on severity of infection, type of infection, associated epithelial defect, and postoperative inflammation. Fungal keratitis requires longer treatment than bacterial. Other postoperative problems including formation of synechia, shallowing of AC, secondary glaucoma, non-healing epithelial defect, and loose sutures were managed with supportive medications and/or with procedures such as AC reformation, synechiolysis, trabeculectomy,? amniotic membrane transplant and resuturing of the wound.

Postoperative regime not addressed. In what dose & what duration was anti microbial agents used, systemic antimicrobial use, topical steroid use & if so which one, NSAIDS used if any, & duration of post op medication not discussed.

RESULTS

Demographic parameters

Overall, 358 eyes of 350 patients had undergone TPK for infective keratitis; 66% were male. Average age of the patients was 48.4±15.7 (range 4 to 84 years). Sixteen patients had undergone TPK more than once in the same eye. In all, 102 patients were from the urban area, whereas remaining 248 (70.8%) patients were from rural districts of north India.

Donor cornea details

Average waiting time of patients for TPK was 4.9±4.52 days. Mostly corneas which we used were of B-negative or C grade. The endothe­lial cell count was not considered as it was not relevant. Mean recipient rim size was 8.52±0.88 mm(not very big size).Age of donor, storage media, time from procurement to transplantation not addressed

Indications for TPK

The main indications for surgery were fungal keratitis (38%) followed by mixed sloughing ulcers (32%).Out of total, 10% of ulcers was perforated. Other indications remain impending perforation, chemical injuries(bound to fail), herpetic eye diseases and graft infection and graft melting.

Microbiological assessment

On microbiological investigation 33% eyes were positive for organisms of which 18% showed pure fungus and 10% showed pure bacteria. The commonest fungus and bacteria isolated were Aspergillus and pseudomonas, respectively.

Outcome and complications

The anatomical success and eradication of infection was achieved in 85.5% eyes. In the postoperative course, 44.4% developed secondary glaucoma 7.8% eyes required re-surgery(for?). Overall functional success with a visual acuity above 3/60 was 9.4%. Fungal keratitis had a higher anatomical success, and graft clarity and less complication rates compared to bacterial or mixed infection.

DISCUSSION

The mean age group of our patients, 48 years, is similar to that in Northern India, Nepal and Iran, but varies with other Asian countries where the mean age is 55 years.^4-8 Male preponder­ance of the patients is also seen in other studies in India, Singapore, and Iran.^4-8 This could be because more men work outside home and are prone to work-related trauma and superadded infections. There could also be gender bias in health care in a male-dominant society like ours. Corneal ulcers presenting in the Institute of Ophthalmology are severe, impending to perforate or perforated. Maximum TPKs were done for fungal corneal ulcers unlike other studies reported. Sedghipour et al and Sukhija and Jain reported even greater proportion of perforated ulcers, 76%–88%.^5-8. Study done in Nepal also reported high number of perforated as a indication of TPK. Probable reason for less number  of TPK performed for perforation can be use of glue with BCL in patients of small perforations and impending perforation as a primary modality of management.

Fungal keratitis was the most common cause of TPK in our study unlike other studies. Bacterial keratitis is more common than fungal in other studies.^9-11 We had a large number of culture-negative cases. This could be because patients were already treated with various antimicrobials before they came to our institute. In other studies done in Asia, this ratio between bacterial to fungal, ranges from 1:0.7 to 1.3:1.^4-7 Aspergillus is the com­monest fungus needing TPK in North India and Taiwan but in Singapore, it is Fusarium. In Taiwan and Singapore, the commonest bacterium isolated in TPK cases is Pseudomonas, in which the predisposing factor for ulcer is contact lens but in India, it is Staphylococcus.^4,6,7 In our study Pseudomonas culture was more than the Staphylococcal.

Cataract surgery was the commonest procedure combined with TPK. Other reports mention TPK combined with cata­ract surgery in 3%–50% of TPK.³

Postoperatively, TPK has a high incidence of severe AC reaction, shallow AC, synechia, and high intraocular pressure. Sony et al mentioned a range of postoperative AC shallowing as 9% to 31% in various studies.4 In our study, 27% needed AC reformation. Some cases required cataract extraction for deepening of AC and prevention of synechia. There is a high chance of primary graft failure on repeated intervention.

Recurrence of infection is a very undesirable complica­tion which may again stake the structural integrity of the operated eye. Our study shows fungal ulcers undergoing TPK have shown recurrence. Other reports mention recurrence rate of fungus after TPK to be 7.3%–10%.³ Sharma et al mentioned cure rate (absence of recurrence) in fungus as 69%–90%.² Our high recurrence rate could be because of residual infection in the recipient rim in three cases, associated fungal endophthalmitis in few cases, and because many fungal corneal ulcers presenting in our institute were advanced with extensive invasion of anterior segment structures. Sharma et al quoted the cure rate of bacterial ulcers as 90%–100% and our bacterial cure rates were lowerthan this range.² Recurrence of herpetic keratitis varies widely among different studies from 8.8%–75%.³ In our study, overall anatomic stability after primary TPK was 89%, which is similar to that reported by Cristol et al and Sukhija and Jain.^8-12 Anatomic stability was more in TPK performed for fungal than for bacterial ulcers, opposite of as reported in Nepal study. Sharma et al and Chen et al reported 90%–92% anatomical success rate for bacterial and 84.6%–88.5% for fungal ulcer.^4,6

Late postoperative keratitis is quite common in patients who had undergone keratoplasty surgery. Risk factors have been loose sutures, topical steroid, and decreased sensation.¹³ The course of microbial keratitis in corneal graft progresses rapidly due to compromised ocular surface and use of topical steroids. Vajapayee et al mentioned the rate of infective keratitis after keratoplasty as 1.46%–11.9%.¹³ Maximum patient had a visual acuity less than 3/60 unlike other studies which show fair gain postoperatively.³ Sharma et al reported 14.8% patients with a visual acuity above 6/60 at 1-year follow-up.⁴ In our study, 48 patients had undergone cataract surgery at various times. Full visual rehabilitation such as cata­ract surgery, regraft, and correction of astigmatism was not performed for many patients as most of our unilateral blind patients were not willing to undergo a second surgery.

Graft rejection was present in 20/145 (13.7%) cases who followed up. Sony et al reported that rejection rates in TPK varied from 14.6% to 52.1%.4 In our study, 26 cases were edematous decompensated graft. In this group, it was clinically difficult to distinguish whether edema resulted due to late decompensation or rejection which happened at the time patient did not follow-up. This could be the reason why graft rejection was reported less in our study. We had only 20% of rejections being reversed with treatment whereas Sedghipour et al report reversal of graft rejection in 66.6% of cases.⁵ Low rate of reversal could be due to patients not able to present timely.(How was rejection managed- step up of steroids, dose, IV Methylprednesone given?)

Secondary glaucoma is mostly due to extensive periph­eral anterior synechiae and may lead to graft failure and blind eye. We noted a high incidence of secondary glaucoma of 44.4% compared to that reported by Sharma et al and Sukhija and Jain who mentioned 25% and 22%, respectively.^4,8 Although presence of secondary glaucoma is not significant statistically, medically uncontrolled glaucoma was found more in fungal group than bacterial. This could be because of controlled use of steroids in fungal kerati­tis in early postoperative period. Other reports show 2%–50% incidence of secondary glaucoma in fungal TPK.^3,14  use of postop oral anti glaucoma medications not addressed

A limitation of our study would be a large number of cases were not positive for any strain and the diagnosis was based on clinical presentation.

CONCLUSION

Therapeutic keratoplasty remains a mainstay procedure to preserve the eye in severe corneal infections. There is a high incidence of postoperative glaucoma and graft failure in such a surgery. Fungal keratitis has a better outcome than bacterial keratitis( Doubtful).

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