Purpose. To understand the influence of preoperative corneal conditions, combined implant surgeries, and subsequent rejection on the aqueous flare value following penetrating keratoplasty (PK).
Methods. A total of 86 eyes of 86 patients were included. PK alone was performed on eyes with keratoconus (n = 7), corneal scar (from previous trauma or nonherpetic infection; n = 19), pseodophakic bullous keratopathy (PBK) (n = 16), and for regraft (n = 14). Combined ECCE and PC-IOL implantation (triple procedure) was performed on 17 eyes with corneal scar, and combined AC-IOL exchange was performed on 13 eyes with PBK. Aqueous flare was measured with a laser flare-cell meter at 1 week and 1, 3, 6, 12, and 24 months postoperatively. The mean follow-up was 24.7 (range 7–76) months.
Results. There were 11 cases (12.8%) of endothelial rejection (two in PK for corneal scar group, two in triple procedure group, two in PK for PBK group, three in PK and AC-IOL exchange group, and two in regraft group). Two corneas in PK for corneal scar group, one in PK and AC-IOL exchange group, and one in regraft group cleared up later; the remaining seven cases failed subsequently. Another 10 grafts (11.6%) failed from other causes. Eventually, 69 grafts (80.2%) remained clear at last follow-up. There was a significant difference in aqueous flare values among eyes undergoing PK only for keratoconus, corneal scar, PBK, and regraft from 1 week to 3 months postoperatively. In the corneal scar group, aqueous flare value was significantly higher from 1 week to 3 months when combined with cataract surgery. In the PBK group, the value was significantly higher from 1 week to 1 month and 6 months again when combined with AC-IOL exchange. Notably, significantly higher flare values were measured from 1 week to 6 months in eyes with later rejection.
Conclusions. Preoperative diagnoses and additional implant surgeries influenced the aqueous flare counts at the early postoperative period. Persistently elevated flare value may be associated with later rejection.
Allograft rejection is one of the most common causes of graft failure following corneal transplantation. Delayed or inadequate treatment often results in irreversible graft edema, and the success rate for subsequent regraft also decreases. Although recipients at risk can be identified by preoperative diagnoses 1,2 and by some laboratory studies, 3,4 allograft rejection usually arises from a seemingly normal graft. 5 A noninvasive device for predicting imminent rejection would be invaluable.
In recent years, the He-Ne laser flare-cell meter (LFCM) has been widely used in quantitative determination of intraocular inflammation, 6,7 including that following uncomplicated PK and allograft rejection. 8,9 In the study, Küchle et al found that aqueous flare returned to normal 6 weeks after PK for keratoconus and corneal dystrophies, and during rejection, the blood-aqueous barrier (BAB) is disrupted as a result of inflammation, which is manifested as elevated aqueous flare and cell counts. Recently, Nguyen et al further compared breakdown of the BAB after PK with or without simultaneous extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC-IOL) implantation. They found a delayed return to normal flare value 6 months postoperatively following the triple procedure. 10 From these results, the authors concluded that aqueous flare quantification may be useful for early detection and treatment monitoring of allograft rejection. 8–10 However, in these studies, the recipients were at low risk of rejection (keratoconus, Fuchs and other corneal stromal dystrophies) and were without previous intraocular surgeries. Because disorders associated with previous intraocular insults such as pseudophakic bullous keratopathy (PBK) and regraft are also leading causes for PK, and cataract extraction and/or IOL implantation are often performed simultaneously with PK, the effect of preoperative diagnoses and combined implant surgeries on the severity and duration of breakdown of the BAB can not be overlooked. The following study described the use of LFCM to understand the long-term effect of preoperative corneal conditions and combined implant surgeries on the aqueous flare changes and subsequent rejection following PK. The correlation of aqueous flare value and subsequent rejections was also investigated.