Fungal corneal ulcers with complications often become difficult to control with medical treatment. Most of the times these refractory cases are amenable to therapeutic transplantation [18]. However, therapeutic corneal transplantation (i.e., keratoplasty) with donor cornea is often not possible due to the unavailability of the latter. Alternatives transplant tissues include conjunctival flap and amniotic membrane graft. Conjunctival flap (CF) surgery is famous among surgeons for producing stable ocular surfaces and repressing inflammation[19]. While amniotic membrane graft (AMG) was to be beneficial adjuvant therapy for improved corneal healing and visual acuity in fungal keratitis[14]. Our study is one of the very few that compared CF and AMG transplantation in non-healing fungal corneal ulcers.
We found that both CF and AMG surgery showed a statistically similar proportion of corneal healing and epithelialization time. Pain improved substantially in both groups, with no patients feeling pain by 120 days. However, AMG transplantation showed a significantly better improvement in visual acuity than CF. Flap failure was more common in the CF group than AMG. But the difference wasn't statistically significant. Our findings agree with Abdulhalim et al[20]. in terms of success rates and epithelialization time but differ in terms of visual acuity improvement. Contrary to our results, they noted a statistically similar visual acuity improvement between CF and AMG groups.
The effectiveness of AMG in the treatment of corneal ulcer and perforations were documented in many previous studies. A systematic review and meta-analysis on AMG transplantation in infective keratitis reported shortened corneal healing time and better-uncorrected distance visual acuity[14]. AMG has documented properties against angiogenesis, inflammation, scarring, and fibrosis[21]. The non-vascular nature of AMG matches that of the cornea and might explain the better improvements in patients' visual acuity compared to conjunctival flaps. Many surgeons have used conjunctival flaps since Gunderson introduced the procedure in the management of ocular surface disease in 1958[11]. It has been a benchmark surgery because of its wide-ranging therapeutic effects, including its anti-inflammatory and pain-relieving properties. Also, it promotes healing by vascularization and is easily obtainable. Hence, it was widely practiced till sophisticated technological progress led to the adoption of alternatives like penetrating keratoplasty, amniotic membrane transplantation, and epithelial transplantation in the developed world[19]. But a limited availability of these alternatives in the developing world leaves conjunctival flap a better choice for non-healing keratitis. Our study results support the use of both modalities for the healing of refractory fungal corneal ulcers. However, if minor improvement of visual acuity is wanted, AMG appears to do better.
We found 6 cases of flap failures during the study. Two-thirds of the failed eyes had perforations, and two-thirds of patients had diabetes. Both of these are established factors associated with poor healing. Diabetes, particularly if uncontrolled, causes impediments in recovery by aberrations in wound angiogenesis[22]. While corneal perforation due to fungal keratitis makes the clearance of fungi difficult[18]. Hence, blood sugar levels need close monitoring and strict control in diabetic patients undergoing keratoplasty. Moreover, perforations should be evaluated for more invasive techniques like penetrating keratoplasty, and AMG can be used as a stoppage measure or to delay the invasive procedure.
Flap rejection or wrinkling led to the irreparable painful blind eye. We had to eviscerate those eyes. A nontraumatic painful blind eye is one of the common indications for evisceration documented in other studies[23]. and is performed to improve pain and maintain the cosmetic integrity of the face.
Causative fungi and risk factors of corneal ulcer among our refractory fungal corneal ulcer patients matched previous studies. Like earlier reports, we found Fusarium and Aspergillus as predominant organisms[24]. Agricultural trauma was the most common risk factor for developing fungal corneal ulcers among our participants, which conforms with the findings of Gopinath and colleagues[25]. This also explains a predominance of male patients developing fungal corneal ulcers.
Our study had several limitations. Keeping a control group for comparison with other surgical procedures like corneal transplants was not possible. As medical refractory fungal corneal ulcer is not much common, our study was limited to the small number of patients. Nevertheless, this study was one of the few reports which compared the effectiveness of both conjunctival flap surgery and amniotic membrane graft in a recalcitrant fungal corneal ulcer. The result would help design future management strategies and plan large-scale studies.