[Effect of ocular compression on anterior chamber dimensions in cataract surgery using topical anaesthesia]

Ocular compression is part of the preparation before cataract surgery to reduce the incidence of a positive intraoperative pressure. The purpose of this clinical study was to assess the influence of ocular compression on the anterior chamber dimensions and biometric parameters before cataract surgery using topical anaesthesia.

In a prospective, comparative observational study the biometric parameters were assessed with slitlamp-adapted anterior segment OCT (SL-OCT, Heidelberg Engineering) and ultrasound biometry (A-Scan+, Sonomed) in 51 consecutive patients (51 eyes) with a mean axial eye length of 22.90 ± 1.05 mm before cataract surgery. The measurements were performed in all patients before and immediately after ocular compression (Oculopressor G-15392, Geuder). In 32 patients the measurements were repeated 10 minutes after ocular compression.

The optical and acoustic values of the anterior chamber depth did not change significantly after ocular compression (p > 0.05). Digital gonioscopy with OCT revealed a mean increase of the anterior chamber angle of 2.37° (p < 0.001) from 45.75 ± 7.28° to 48.12 ± 7.28°, and the angle opening distance of 37 µm (p = 0.017) from 627 ± 184 µm to 664 ± 162 µm. Also the average acoustic axial vitreous distance decreased significantly from 15.22 ± 0.98 to 15.18 ± 0.96 mm (p = 0.034) with a posterior shift in the relative lens position (p = 0.018).

In this clinical study, only slight anterior chamber and biometric changes were observed after ocular compression before cataract surgery using topical anaesthesia. There was a significant increase of the anterior chamber angle and angle opening distance with a concomitant decrease of the vitreous distance and shifting of the iris lens diaphragm.