The morphologic and quantitative evaluation of ocular anterior chamber parameters after laser peripheral iridotomy in primary angle-closure glaucoma eyes

Background

Pentacam anterior segment analysis system(Pentacam) is more accurate in the quantitative evaluation of ocular anterior segment in primary angle-closure glaucoma (PACG) eyes than slit lamp microscope and ultrasound biomicroscope (UBM). However, its accuracy in the earlier stage of PACG before and after YAG laser peripheral iridotomy (LPI) is not fully elucidated.

Objective

This study was to assess the effect of YAG LPI in PACG patients with Pentacam.

Methods

A prospective self-controlled study was performed.Thirty-five fellow eyes (pre-clinical stage of PACG) of acute PACG and 35 fellow eyes of chronic PACG were included in the Second Hospital of Hebei Medical University from July, 2012 to December, 2013.YAG LPI was performed on the eyes, and the parameters of ocular anterior segment including central anterior chamber depth (ACD), anterior chamber volume (ACV) and peripheral anterior chamber angle (ACA) were measured and compared by Pentacam before and 1 day, 7 days, 28 days after operation.This study was approved by the Ethic Committee of the Second Hospital of Hebei Medical University and informed consent was obtained from all subjects.

Results

In pre-clinical stage of PACG eyes, the postoperative ACD and ACV values were increased in comparison with preoperation, showing significant differences among various time points (ACD: F=6.783, P=0.004; ACV: F=19.090, P=0.000), and no significant difference was found in ACA among different time points (F=0.153, P=0.928). In the fellow eyes of chronic PACG, the postoperative ACD and ACV values were larger than those of preoperation, with significant differences among various time points (ACD: F=21.576, P=0.000; ACV: F=47.506, P=0.000), and no significant difference was found in ACA among different time points (F=0.581, P=0.629). The change values of ACD and ACV were (0.064±0.022)mm and (27.840±4.963)mm³ in the eyes of pre-clinical stage of PACG, and those in the fellow eyes of chronic PACG were (0.047±0.020)mm and (21.000±3.278)mm³, showing significant differences between the two groups (ACD: t=2.783, P=0.008; ACV: t=5.749, P=0.000).

Conclusions

Pentacam allows easy, fast, automatic and non-contact quantification and three-dimension image of the anterior chamber parameters before and after YAG LPI in pre-clinical stage of PACG eyes and fellow eyes of chronic PACG.The ACD deepens and ACV increases after LPI in glaucomous eyes, especially in the pre-clinical stage of PACG eyes.

Glaucoma, angle-closure/surgery; Anterior chamber/pathology; Biometry; Imaging, three-dimensional; Diagnostic techniques, ophthalmological/instrumentation; Laser therapy; Iridectomy; Pentacam anterior segment analysis system