"En bloc" combined 270-degree keratolimbal allograft with central lamellar keratoplasty for severe limbal stem cell deficiency secondary to mustard gas exposure.

Background: Severe limbal stem cell deficiency (LSCD) resulting from chronic and delayed-onset mustard gas keratopathy (MGK) presents substantial management challenges. This article introduces an "en bloc" surgical procedure combining a 270-degree keratolimbal allograft (KLAL) with central lamellar keratoplasty (CLK) as a novel approach to treat this condition.

Methods: A retrospective case series was conducted at Labbafinejad Medical Center in Tehran, Iran, from 2002 to 2019, including 13 eyes from 13 male patients diagnosed with chronic and delayed-onset MGK. Each patient underwent the combined 270-degree KLAL and central LK procedure. A 270-degree peritomy, sparing the superior quadrant, was performed. A lamellar dissection using a crescent blade and a blunt Melles dissector was carried out, extending 2 mm from the limbus. Fresh donor tissue with intact 270-degree limbo-conjunctiva, obtained from a whole globe, was prepared to match the recipient bed and sutured into place. Postoperative outcomes and success including ocular surface integrity, graft longevity, and best-corrected visual acuity (BCVA), were evaluated.

Results: The average follow-up period was 87.6 ± 49.8 months. Surgical success was achieved in 12 of 13 patients (92.3 %). Preoperative BCVA improved from 1.07 ± 0.24 (approximately 20/250) logMAR to 0.63 ± 0.30 (approximately 20/80) logMAR postoperatively. One patient experienced immune rejection of the KLAL graft, while two patients had episodes of corneal rejection, all successfully managed with aggressive immunosuppressive therapy.

Conclusions: The "en bloc KLAL + CLK" procedure demonstrates promising long-term outcomes in managing chronic and delayed-onset MGK associated with severe LSCD. This approach offers advantages, including reduced surgical complexity, minimized antigenic load, and better anatomical alignment, leading to successful ocular surface restoration and improved visual acuity.