Ocular hypertension: Correlation of anterior chamber angle width and risk of progression to glaucoma

Abstract

SUMMARYOcular hypertension (OH) is the principal known risk fac tor for the development of open angle glaucoma, 1.2 and an eye with a narrow anterior chamber angle is at risk of developing angle-closure glaucoma.3,4. 5 ). The decision whether or not to treat ocular hypertension is usually made after an assessment of the relative risk of the eye develop ing glaucomatous visual field loss. Factors such as a very high intraocular pressure (lOP), a family history of glau coma, or diabetes mellitus are associated with a greater likelihood of progression to glaucoma, influencing the decision to treat the patient. In managing eyes with ocular hypertension and narrow angles (OHNA), the clinician must also assess the risk of the eye developing angle closure glaucoma (ACG) and decide whether the narrow angle itself is primarily responsible for the raised pressure. If relative pupillary block is present and causing periph eral iris bombe with obstruction of the trabecular mesh work, then a peripheral iridectomy or laser iridotomy (LI)

Incidence of occludable angles in a high-risk Mongolian population

“…Two patients developed PACG (8%), PAS were detected in a further five patients (20%), and symptoms suggestive of sub-acute angle closure were elicited in three (12%) 13. A summary of information available on the natural history of angle closure is shown in table 2.…”

Comparison of techniques for measuring anterior chamber depth: Orbscan imaging, Smith’s technique, and van Herick’s method

“…In addition, evaluation of ACD also serves to identify people for whom pupillary dilation may cause angle-closure glaucoma [3]. ACD values ≤2.5 mm are considered shallow and at greater risk from an attack of angle-closure glaucoma following pupil dilation [4,5].…”

“…In this technique, LCDvh is assessed in relation to corneal thickness and is graded using a four-point scale with each grade indicating the probability of angle closure: grade four (wide open); grade three (incapable of closure); grade two (possible closure); grade one (dangerously narrowed angle) [6]. A grade of two or less has been correlated with acute closedangle glaucoma [5]. Studies have reported suboptimal results when using LCDvh to screen for primary angle closure [2,8,9], although Foster et al [10] found that a seven-point grading system resulted in 99% sensitivity compared to gonioscopic evaluation.…”

Anterior Chamber Angle Assessment Techniques

“…Male subjects usually have larger anterior chamber dimensions than female subjects. There is a direct association between narrow anterior chamber angle and shallow anterior chamber depth (Wishart and Batterbury, 1992). Consequently, the ACD quantification represents an indirect means of assessing the anterior chamber angle and identifying patients who are more likely to develop PACG.…”

“…Consequently, the ACD quantification represents an indirect means of assessing the anterior chamber angle and identifying patients who are more likely to develop PACG. Usually eyes with ACD <2 mm are considered at risk (Wishart and Batterbury, 1992). …”