Ultrasound biomicroscopic quantification of the change in anterior chamber angle following laser peripheral iridotomy in early chronic primary angle closure glaucoma

Assessment of Iridotrabecular Contact and Its Association With Intraocular Pressure After Phacoemulsification in Primary Angle Closure

PURPOSE

To investigate the association between the quantitative assessment of iridotrabecular contact (ITC), measured by swept-source anterior segment optical coherence tomography (SS AS-OCT), and intraocular pressure (IOP) control after phacoemulsification in patients with primary angle closure disease (PACD).

DESIGN

Retrospective, clinical cohort study.

METHODS

Preoperative and postoperative anterior chamber angle parameters were measured using SS AS-OCT. IOP was measured preoperatively and until 6 months postoperatively. Percent IOP reduction and fluctuation after surgery were calculated, and their relationships with SS AS-OCT parameters were assessed by correlation analyses and locally weighted scatterplot smoothing (LOWESS) regression with change-point analysis.

RESULTS

A total of 51 eyes of 51 PACD patients were included. Preoperative ITC index and area (r = 0.626, r = 0.551), as well as changes in ITC index and area (r = 0.632, r = 0.543) after surgery, were significantly correlated with postoperative IOP reduction, after adjusting for age and gender (all P <.001). Higher postoperative ITC index (r = 0.405, P = .005) and ITC area (r = 0.460, P = 0.001) were associated with greater postoperative IOP fluctuations. Change points on LOWESS curves were observed for preoperative ITC index (33.0%) and change in ITC index (27.0%) and percent IOP reductions were significantly correlated with them above (β = 0.386, β = 0.664, all P < .001) but not below the change points.

CONCLUSIONS

Quantitative assessment of circumferential ITC can predict postoperative IOP control after phacoemulsification, and thus it may be used as a reference for determining lens extraction in PACD eyes.

Optical coherence tomography analysis of anterior segment parameters before and after laser peripheral iridotomy in primary angle-closure suspects by using CASIA2

Background

Laser peripheral iridotomy (LPI) is effective in primary angle-closure suspects (PACS); however, predictors for anterior segment alterations after LPI are limited. We aimed to evaluate the anterior segment biometric parameters before and after LPI in PACS using the recently developed, CASIA 2 device of anterior segment optical coherence tomography (AS-OCT).

Methods

We performed LPI in 52 PACS. Anterior segment parameters, including anterior chamber depth (ACD), anterior chamber width (ACW), anterior chamber volume (ACV), iris curvature (ICURVE), iridotrabecular contact (ITC), lens vault (LV), lens thickness (LT), radius of the lens, angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), and trabecular iris angle (TIA) at different distances (i.e., 500 μm from the sclera spur), were evaluated before and after LPI using CASIA 2.

Results

Eyes of PACS after LPI had a greater ACV, AOD, ARA, TISA, and TIA, and a lower ITC and ICURVE (all p < 0.001) than those before LPI. On a 360° scan, the anterior chamber angle in the superior quadrant increased the most after the LPI. A higher baseline LT was significantly associated with a greater postoperative increase in AOD 500, ARA 500, TISA 500, and TIA 500 (p = 0.001, p = 0.010, p = 0.004, and p < 0.001, respectively).

Conclusions

We found that LPI widens the anterior chamber angle in the PACS, especially, in the superior quadrant around the iridotomy hole. Eyes with a thicker lens are more likely to experience angle opening because of the LPI.

Long-Term Effect of Early Phacoemulsification in Primary Angle Closure Glaucoma Patients with Cataract: A 10-Year Follow-Up Study

Purpose

To assess the 10-year effects of early phacoemulsification with intraocular lens (IOL) implantation in primary angle closure glaucoma (PACG) patients with cataract.

Patients and Methods

This prospective cohort study included 102 eyes of 102 patients with PACG. All patients had coexisting cataracts compromising vision. Patients underwent phacoemulsification and foldable IOL implantation. The main outcome measures were anterior chamber depth (ACD), angle width, value of intraocular pressure (IOP), and number of medications needed postoperatively and during follow-up.

Results

Half (53%) of the patients were female, with ages ranging from 55 to 73 with a mean of 59.82±5.19 years. Mean IOP decreased significantly from 22.15±2.08 mmHg at baseline to 14.08±2.13 mmHg postoperatively (p˂ 0.05). The ACD increased from 2.2±0.21 preoperatively to 3.73±0.25 postoperatively (p˂0.001). Nasal angle width increased postoperatively to 40.05±2.09 compared to the preoperative value of 16.02±2.08 (p˂0.001). Temporal angle width increased from 13.05±2.07 to 41.9600±1.94 (p˂0.001). Anti-glaucoma treatment significantly decreased postoperatively (p˂0.001). A significant positive correlation was detected between ACD and angle width, while a negative correlation was detected between IOP and both ACD and angle width (p˂0.001). There was also a significant negative correlation between postoperative angle width and IOP (p˂0.001). Preoperative lens thickness was positively correlated with preoperative IOP and number of medications, while it was negatively correlated with preoperative AC depth and angle width. Preoperative lens thickness positively correlated with postoperative IOP and medications. Complete and qualified success was achieved in 69.65% and 30.4% of cases, respectively, while 2.9% failed to be controlled. Visual acuity significantly improved from 0.17±0.1 to 0.9±0.08 (p˂0.001). All parameters showed high stability throughout the follow-up period.

Conclusion

Phacoemulsification with IOL implantation is a safe and effective early modality for long-term control of IOP in PACG patients with coexisting cataract. The effects can persist for at least 10 years.

Anterior-segment imaging for assessment of glaucoma

This article summarizes the physics, technology and clinical application of ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT) for assessment of the anterior segment in glaucoma. UBM systems use frequencies ranging from approximately 35 to 80 MHz, as compared with typical 10-MHz systems used for general-purpose ophthalmic imaging. OCT systems use low-coherence, near-infrared light to provide detailed images of anterior segment structures at resolutions exceeding that of UBM. Both technologies allow visualization of the iridocorneal angle and, thus, can contribute to the diagnosis and management of glaucoma. OCT systems are advantageous, being noncontact proceedures and providing finer resolution than UBM, but UBM systems are superior for the visualization of retroiridal structures, including the ciliary body, posterior chamber and zonules, which can provide crucial diagnostic information for the assessment of glaucoma.

Anterior segment imaging in glaucoma

Anterior segment imaging allows objective assessment of the anterior segment of the eye, particularly the anterior chamber angle. Both qualitative and quantitative analyses are possible and aid in detecting and managing closed-angle and open-angle mechanisms in various forms of glaucoma. This review focuses primarily on anterior segment optical coherence tomography and ultrasound biomicroscopy, with emphasis on principles of technology, commercially available devices, and clinical applications in glaucoma with potential advantages and disadvantages of each technology.

Changes in Caucasian eyes after laser peripheral iridotomy: an anterior segment optical coherence tomography study

BACKGROUND

To evaluate by anterior segment optical coherence tomography (AS-OCT) the changes in the anterior chamber structures in Caucasian eyes after laser peripheral iridotomy (PI).

METHODS

Retrospective study of consecutive Caucasian primary angle closure suspect (PACS), primary angle closure (PAC) or primary angle closure glaucoma (PACG) patients who underwent laser PI over a 25-month period at a specialist glaucoma practice. The AS-OCT images of the temporal and nasal angles (in light and dark) before and after laser PI were analysed. The parameters studied were trabecular-iris angle (TIA), angle opening distance (AOD), trabecular-iris space area (TISA), trabecular-iris contact length (TICL), iris thickness (IT) and maximum iris bow height (MIBH).

RESULTS

Images of 71 eyes of 71 patients were assessed. The mean age at laser PI was 60.3 ± 10.0 years. Forty (56.3%) were women, and 14 (19.7%) had PACG. The mean time from laser PI to the follow-up AS-OCT scan was 5.92 ± 3.22 weeks. The IT did not alter significantly after laser PI, but there were significant increases in the TIA, AOD and TISA, as well as a significant decrease in MIBH, in both light and dark. There was no difference in the magnitude of change seen between the temporal and nasal angles, or between PACS/PAC and PACG eyes.

CONCLUSION

In Caucasian eyes, laser PI resulted in significant angle widening (increased TIA, AOD and TISA) and iris profile flattening (decreased MIBH) at the temporal and nasal angles based on AS-OCT imaging in both light and dark.

Determination of anterior segment changes with Pentacam after phacoemulsification in eyes with primary angle-closure glaucoma

BACKGROUND

To investigate changes of anterior segment morphology in primary angle-closure glaucoma after phacoemulsification using the Pentacam system.

DESIGN

Prospective, interventional study, Zhongshan Hospital of Sun Yat-sen University.

PARTICIPANTS

Eighty-five eyes from 60 patients with primary angle-closure glaucoma undergoing phacoemulsification.

METHODS

  Intraocular pressure was measured by Goldmann applanation tonometry. Anterior segment morphology was assessed using the Pentacam camera.

MAIN OUTCOME MEASURES

The intraocular pressure, central anterior chamber depth, peripheral anterior chamber depth, anterior chamber volume, pupil diameter and anterior chamber angle preoperative and 3 months postoperative.

RESULTS

A total 78 eyes of 55 patients with primary angle-closure glaucoma were included in the analysis. Thirty-two eyes (41.0%) had acute primary angle-closure glaucoma, and 46 eyes (59.0%) had chronic primary angle-closure glaucoma. In both groups, statistically significant decreases in intraocular pressure and increases in anterior chamber volume, central anterior chamber depth, peripheral anterior chamber depth and anterior chamber angle inferiorly, nasally, temporally and superiorly were observed at 3 months after phacoemulsification (all P < 0.001).

CONCLUSIONS

Phacoemulsification induces significant changes in anterior segment morphology in primary angle-closure glaucoma accompanied by a significant fall in intraocular pressure in the short term.