SS-OCT assessment of ITC after phacoemulsification
Reviewed by Jonathan Chan

This is a multicentre randomised controlled trial of 22 patients with primary angle closure glaucoma with peripheral anterior synechia and peripheral primary angle closure glaucoma (PACG) with peripheral anterior synechia (PAS) detected by indentation gonioscopy was randomised into two groups. The first group is phacoemulsification only (PE (n=11)) and phacoemulsification + goniosynechialysis (GSL) (n=11). These patients were compared with the change in the iris-trabecular contact (ITC) area using swept–source optical coherence tomography (SS-OCT) in eyes with primary angle closure glaucoma and that had cataract surgery with phacoemulsification and lens implantation. The anterior chamber angles were evaluated by SS-OCT under dark conditions before and 12-months after surgery using three-dimensional angle analysis scan protocol that simultaneously obtains 128 cross-sectional radial scans across the anterior chamber at equal intervals (every 1.4°). The ITC area, defined as an area of the extent of the circumferential contact of the peripheral iris to the angle wall, was computed automatically by SS-OCT after and observer marked the scleral spurs of all 128 scans of each eye. Of the patients, 77.3% were women with a mean age ±SD of 67.3 ≥5.8 years. The ITC area was significantly reduced in the PE+GSL group compared with the PE alone group (10.2mm2 vs 4.6mm2, β= 0.54, p=0.03) after adjusting for age, gender, intraocular pressures, extent of PAS and pupil diameters before surgery. Smaller iris volumes at baseline was associated with greater ITC area reduction by PE+GSL (β=0.728, p=0.03). The authors conclude that patients that had PE+GSL surgery have a greater reduction in circumferential ITC area than eyes that undergo PE alone. The authors also comment the limitations of this study include the use of a single observer for gonioscopy and SS-OCT image grading, which could result in a systematic bias. In addition, the sample size was relatively small and 12-months could be too short a period to evaluate the long-term outcome of the ITC area changes with time. The limitation of the clinical detection and quantification of PAS could also be variable.

Swept-source optical coherence tomography assessment of iris-trabecular contact after phacoemulsification with or without goniosynechialysis in eyes with primary angle closure glaucoma.
Tun TA, Baskaran M, Perera SA, et al.
BRITISH JOURNAL OF OPHTHALMOLOGY
2015;99:927-31.