Objective:To investigate whether peripheral corneal neovascularization in bullous keratopathy(BK) is due to conjunctivalization,a sign of limbal stem cell deficiency.Design:Observational case-control study.Participants:Sixteen BK patients.Methods:Patients were divided into 2 groups:BK without peripheral neovascularization [NV(-) group;5 patients,5 eyes] and BK with neovascularization [NV(+) group;11 patients,13 eyes].Evidence of conjunctivalization was evaluated by periodic acid-Schiff staining of impression cytology samples from the peripheral vascularized cornea.The 2 groups’ durations of disease also were compared.Penetrating keratoplasty(PK) was performed in all 16 cases,and the 2 groups’ durations of reepithelialization after PK were compared.Main Outcome Measures:Presence of goblet cells using impression cytology,duration of BK,and duration of postoperative reepithelialization.Results:Goblet cells were found on the peripheral corneal surface in all eyes in the NV(+) group.However,all eyes in the NV(-) group were negative for goblet cells(P< 0.000 1) .Duration of disease was 14.4± 5.4 months in the NV(-) group and 66.2± 65.5 months in the NV(+) group(P=0.030) .Duration of postoperative epithelialization was 6.2± 2.2 days in the NV(-) group and 28.8± 36.5 days in the NV(+) group(P=0.046) .Conclusion:Conjunctivalization of the peripheral cornea and delayed postoperative epithelialization in BK patients with NV suggest the presence of limbal stem cell deficiency in such patients.Patients with long-standing disease were found to be more prone to neovascularization.For this reason,early surgerymay lead to a better surgical outcome. Objective: To investigate whether peripheral corneal neovascularization in bullous keratopathy (BK) is due to conjunctivalization, a sign of limbal stem cell deficiency. Design: Observational case-control study. Participants: Sixteen BK patients. Methods: Patients were divided into 2 groups: 5 patients, 5 eyes] and BK with neovascularization [NV (+) group; 11 patients, 13 eyes]. Evidence of conjunctivalization was evaluated by periodic acid-Schiff staining of impression cytology samples from the peripheral vascularized cornea. The 2 groups ’durations of disease also were compared. Penetrating keratoplasty (PK) was performed in all 16 cases, and the 2 groups’ durations of reepithelialization after PK were compared. Mitogen Outcome Measures: Presence of goblet cells using impression cytology, duration of BK, and duration of postoperative reepithelialization. Results: Goblet cells were found on the peripheral corneal surface in all eyes in the NV (+) group. , all eyes in the NV (-) group were negative for goblet cells (P <0.000 1). Duration of disease was 14.4 ± 5.4 months in the NV (-) group and 66.2 ± 65.5 months in the NV (+) group P = 0.030). Duration of postoperative epithelialization was 6.2 ± 2.2 days in the NV (-) group and 28.8 ± 36.5 days in the NV (+) group (P = 0.046) .Conlusion: Conjunctivalization of the peripheral cornea and delayed postoperative epithelialization in BK patients with NV suggest the presence of limbal stem cell deficiency in such patients. Patients with long-standing disease were found to be more prone to neovascularization. For this reason, early surgery may lead to a better surgical outcome.