[Impact of anterior chamber geometry on intraocular pressure rise after penetrating keratoplasty - Comparison between elective and emergency procedures].

BACKGROUND

Secondary ocular hypertension and glaucoma are severe complications after penetrating keratoplasty (PKP), which increase the risk of graft failure and irreversible loss of vision.

PURPOSE: Analysis of intraocular pressure (IOP) elevation in relation to the changes of anterior chamber geometry comparing elective and PKPs à chaud.

METHODS

This retrospective study at the Department of Ophthalmology, Saarland University Medical Center in Homburg/Saar included 148 eyes after PKP (123 elective and 25 PKPs à chaud). Between 2014 and 2021 treatment data were documented preoperatively and postoperatively after 6-8 weeks, after partial (18 ± 3 months) and after complete (31 ± 6 months) suture removal. The study analyzed visual acuity, IOP, Pentacam® HR (OCULUS GmbH, Wetzlar, Germany) measurements with central and peripheral corneal pachymetry (CCT, PCT), anterior chamber angle (ACA), anterior chamber depth (ACD) and anterior chamber volume (ACV).

RESULTS

The anterior chamber geometry of all eyes changed significantly after PKP: early postoperatively (6-8 weeks) the pachymetry increased (p < 0.001), while ACA, ACD and ACV (p < 0.001) decreased. The average increase of IOP (p < 0.001) showed a positive correlation with CCT and a negative correlation with ACD. In contrast to elective keratoplasty, PKP à chaud revealed significantly lower ACDs and ACVs (p < 0.001) and higher PCTs (nasal p < 0.033, temporal p = 0.042). In contrast, significant differences were not observed for IOP, CCT and ACA. Increases in IOP ≥ 25 mm Hg (n = 21) were more frequent in eyes with keratoconus (n = 14) with a high proportion of these cases showing a steroid response (n = 10).

CONCLUSION

After PKP the anterior chamber geometry changes postoperatively; however, anterior chamber changes do not necessarily correlate with an increase in IOP. It is possible that a steroid response has a greater influence on postoperative increases in IOP because no significant anterior chamber flattening occurred postoperatively in eyes with keratoconus. In future prospective studies it is expected that further factors with a potential influence will be identified in the complex system of regulation of postoperative IOP.