This article is more than 5 years old. Information may no longer be current.
Anterior segment parameters linked to acute primary angle closure, study finds
Click Here to Manage Email Alerts
In a recent Ophthalmology study, Sng and colleagues found that anterior chamber depth was shallower and iris curvature was smaller in patients during acute primary angle closure.
The researchers evaluated parameters of anterior segment optical coherence tomography (ASOCT) during acute primary angle closure (APAC) before therapeutic interventions were administered.
Researchers used custom software to measure anterior chamber area, anterior chamber volume, iris area, lens vault, angle opening distance, trabecular iris space area and iris thickness as well as anterior chamber depth (ACD) and iris curvature (I-Curv) in 31 patients with APAC. They used models to determine which measurements were associated with APAC.
Results showed that ACD and I-Curv accounted for 18.1% and 14.1%, respectively, of the variance between APAC occurrence and fellow eyes.
"We have presented new insights into the anterior segment biometric parameters of APAC and fellow eyes during the attack, before therapeutic interventions," the authors concluded. “Shallower ACD and smaller I-Curv were the two most important factors associated with APAC, and we found subtle interocular differences in the anterior segment measurements between the APAC eye and the fellow eye.
"These novel findings have identified ocular biometric parameters that may be significant in the initiation of APAC or could be the consequence of the acutely increased IOP,” they continued. “Anatomic changes in the anterior segment explained only about one-third of the variance in APAC occurrence, and the role of dynamic, systemic and environmental factors should be investigated in future studies."
Perspective
Back to Top
Carl H. Jacobsen, OD, FAAO
In this study, Sng and colleagues use anterior segment ocular coherence tomography to better understand acute primary angle closure (APAC). From a clinical point of view, their results seem intuitively obvious. For example, their finding that anterior chamber depth is reduced in APAC is no surprise, given pupil block is the primary cause of this condition. It was surprising to find that the curvature of the iris was less in APAC. A bowing forward, or increased iris curvature, would be expected with pupil block. However, they soundly propose that the elevated anterior chamber pressure may flatten the iris as APAC is established.
The authors are to be commended for characterizing anatomic differences in APAC eyes and fellow eyes during the acute episode using a novel OCT-based analysis system. However, it is difficult to know whether these differences are an anatomic predisposition or are due to the physiologic changes that occur with extreme, acute IOP elevation. With additional studies, important insights might be gained, but for now this does little to influence current clinical care.
Collapse
Ophthalmol. 2014;doi: 10.1016/j.ophtha.2013.08.004.
Click Here to Manage Email Alerts