Graft survival

Although rapid visual rehabilitation and lack of suture-related problems have popularized Descemet’s stripping endothelial keratoplasty a new study suggests that just like with PK, bacterial keratitis can be a serious issue. New research has found that although some patients suffer terrible bacterial keratitis-related afflictions after DSEK, with proper management, others can heal very well. “Judicious use of topical steroids early in the course of the disease may improve the immediate graft survival,” reported lead study author Jayangshu Sengupta, M.S., Corneal and Ocular Surface Disease Clinic, Priyamvada Birla Aravind Eye Hospital, Kolkata, India. The study was published in the January issue of Eye & Contact Lens.
Cautionary tales

Dr. Sengupta described two case studies as part of the report. The first involved a 66-year-old woman who had undergone DSEK for pseudophakic bullous keratopathy. Subsequently the patient presented with light perception in one eye as well as lid edema, ciliary congestion, and a dense central corneal infiltrate. “Gram-negative bacilli were isolated on Gram stain of direct smear, while cultures grew P. aeruginosa,” Dr. Sengupta reported. “The patient was started on half-hourly topical ciprofloxacin drops (0.3%) and topical atropine drops three times per day. The response to treatment was slow.”
In fact, progressive worsening of the donor lenticule occurred with interface neovascularization. “It was declared as failed DSEK and advised to undergo full-thickness penetrating keratoplasty at a later date,” Dr. Sengupta noted. In the second case, a 55-year-old woman presented with a painful, red right eye seven weeks after DSEK for pseudophakic bullous keratopathy. Best corrected visual acuity was 20/200 and slitlamp revealed a dense temporal paracentral corneal infiltrate. Cultures grew P. aeruginosa.
“The patient was started on half-hourly ciprofloxacin eye drops (0.3%) and atropine eye drops three times per day,” Dr. Sengupta noted.
“When response to treatment was obtained, noted by a decrease in the size of the epithelial defect and in the size and density of the infiltrate after 4 days of initiating therapy, topical dexamethasone (0.1%) was started four times a day.”
Edema cleared after 6 weeks and BCVA improved to 20/40, and the graft remained clear after 3 months. There are several lessons that can be learned from the onslaught of bacterial keratitis in these cases, as well as visual outcomes. “The cases highlight the requirement of prolonged antibiotic prophylaxis after healing of an epithelial defect and discontinuation of BCL [bandage contact lens] after DSEK,” Dr. Sengupta reported. The second case also highlights the importance of early steroidal treatment in such instances. “Although similar quality tissue and similar technique were used in surgery for both cases, the early commencement of topical steroid therapy in case 2 after documenting response seems to be responsible for the favorable graft outcome,” Dr. Sengupta reported. “Although it is debatable, early institution of steroid therapy seems to be the key decisive factor with respect to final graft and visual outcome.”
Dr. Sengupta also speculated as to why bacterial keratitis occurred in both situations. “In both our cases, the epithelial defect had completely healed before the onset of infection,” Dr. Sengupta reported. “Apart from the preexistent corneal decompensation and the isolation of P. aeruginosa from both the cases, we stipulate that the presence of contact lens [after DSEK] and steroid usage led to a long-term change in the local milieu because of hypoxic damage, altered local immune mechanism and relative corneal anesthesia. This in conjunction to discontinuation of antibiotics [after DSEK] may have altered the pathogenicity of the local microbiologic flora, resulting in late-onset microbial keratitis after the epithelial defect had healed.”
Still, Sujatha Mohan, M.D., Rajan Eye Care Hospital, Chennai, India, suggested infection after DSEK—if it’s going to happen—is more likely to happen immediately. That’s because once the eye is sealed after DSEK, it’s less likely to attract infection than PK. “There are no exposed sutures in DSEK,” Dr. Mohan said. “Probably after one or two months, it has an advantage over PK in this respect.” Sutures, which are associated with PK, can form a track that facilitates infection to enter the eye, she said. Dr. Mohan, who performs both PK and DSEK, said she seldom has infections with keratoplasties. “If I do have one, it’s because of long-standing steroid use or broken sutures,” she said. “We have not had any acute bacterial infections for either PK or DSEK.” Part of her prophylaxis regimen includes soaking the corneal button pre-op in an antibiotic medium, which includes gentamicin. She believes in this method of prophylaxis because regardless of whether surgeons choose PK or DSEK, if they use an infected donor, there’s going to be an infection.

Editors’ note: Dr. Sengupta has no financial interests related to this study. Dr. Mohan has no financial interests related to her comments.

Contact information

Mohan: +91 044 2834 0500, rajaneye@md2.vsnl.net.in
Sengupta: jayansu@hotmail.com