Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
J Glaucoma. 2020 Aug;29(8):681-688. doi: 10.1097/IJG.0000000000001572.
Iridotrabecular contact (ITC), a measure of angle closure, can be quantified along with other angle parameters on anterior segment optical coherence tomography (ASOCT). Hence, angle changes and angle closure mechanisms can be detected predicting the efficacy of iridotomy.
To assess 360-degree ITC and ocular parameter changes, after laser peripheral iridotomy (LPI), in primary angle-closure disease (PACD) subgroups.
This was a prospective observational study including 90 subjects, 30 each of primary angle-closure suspect (PACS), primary angle closure (PAC), and primary angle-closure glaucoma (PACG). Anterior segment OCT parameters were measured before and 3 weeks after LPI ITC: central anterior chamber depth, lens vault, angle-opening distance, angle recess area, trabecular iris space area, trabecular iris angle at 500 and 750 μm from scleral spur.
ITC was highest in PACG, 81.43%±22.39%, followed by PAC, 28.53%±21.30%, and PACS, 10.76%± 8.54% (P=0.011). There was a significant decrease in ITC in all 3 groups after iridotomy (P<0.001), with a residual ITC of 68.56%±26.44% in PACG, 18.23%±15.98% in PAC, and 5.13%±5.11% in PACS. A significant positive correlation was seen between the extent of ITC, baseline intraocular pressure, and visual field index. ITC was highest in eyes with exaggerated lens vault (77.3%±32.03%), as compared with eyes having a plateau iris configuration or relative pupillary block configuration (P<0.001).
Iridotomy at any stage of PACD shows a significant decrease in ITC, with areas of residual ITC. Even in PACG, the iridotomy is effective in exposing parts of the trabecular meshwork that had contact earlier. Greater baseline ITC and postlaser ITC are a biomarker for higher intraocular pressure and greater visual field damage, which need lifelong review and appropriate management.
作为一种测量房角关闭的指标，虹膜小梁接触（ITC）可以与前节光学相干断层扫描（ASOCT）的其他角度参数一起定量。因此，可以检测角度变化和角度关闭机制，从而预测虹膜切开术的疗效。
评估原发性闭角型青光眼（PACD）亚组中激光周边虹膜切开术（LPI）后 360 度 ITC 和眼部参数的变化。
这是一项前瞻性观察研究，纳入了 90 名受试者，其中原发性闭角型青光眼可疑（PACS）、原发性闭角型青光眼（PAC）和原发性闭角型青光眼（PACG）各 30 名。在 LPI 前后测量前节 OCT 参数，ITC：中央前房深度、晶状体穹窿、房角开放距离、房角隐窝面积、小梁虹膜空间面积、巩膜突 500μm 和 750μm 处小梁虹膜角度。
PACG 的 ITC 最高，为 81.43%±22.39%，其次是 PAC，为 28.53%±21.30%，PACS 为 10.76%±8.54%（P=0.011）。三组术后 ITC 均显著降低（P<0.001），PACG 残留 ITC 为 68.56%±26.44%，PAC 为 18.23%±15.98%，PACS 为 5.13%±5.11%。ITC 与基线眼压和视野指数呈显著正相关。与平台型虹膜构型或相对瞳孔阻滞构型相比，晶状体穹窿增大（77.3%±32.03%）的眼 ITC 最高（P<0.001）。
在 PACD 的任何阶段行虹膜切开术均可显著降低 ITC，并保留部分 ITC。即使在 PACG 中，虹膜切开术也能有效地暴露早期接触的小梁网部分。较大的基线 ITC 和术后 ITC 是眼压升高和视野损害更大的生物标志物，需要终身复查和适当的管理。
