Distribution and characteristics of peripheral anterior synechiae in primary angle-closure glaucoma

To evaluate the characteristics of peripheral anterior synechiae (PAS) in primary angle-closure glaucoma (PACG).

We reviewed the charts of 155 patients (244 eyes) with PACG. We divided these patients into one of four clinical subtypes: acute angle-closure glaucoma (ACG), chronic ACG, angle-closure hypertension, and ACG suspect. The prevalence, extent, and location of PAS were evaluated according to PACG subtypes. Correlation analysis was used to evaluate relationships between the highest IOP level without treatment and the extent of PAS.

The average degree of angle-closure with PAS was 14.6 +/- 9.1 in eyes that were classified as ACG suspect, 83.8 +/- 48.3 in angle-closure hypertension, 140.5 +/- 31.3 in acute ACG, and 180.3 +/- 31.9 in chronic ACG (ANOVA test, P < 0.05). PAS was most frequently found in the superior part of the eye, especially from 12 to 1 o' clock. The incidence of broad PAS (PAS over 30 degrees in width) was highest in superior part, but the medium and narrow PAS (PAS limited to within 30 degrees in width) was distributed throughout all 12 sectors relatively equally. Prior to a laser iridotomy (LI) and other medical treatments, a positive correlation was found between the highest IOP (intraocular pressure) levels and the extent of PAS in chronic ACG (r = 0.423, P < 0.0001). However, statistically significant relationships were not found between the highest IOP levels before treatment and the extent of PAS in any of the other clinical subtypes.

Our results suggest that acute and chronic ACG patients are most likely to have a greater extent of PAS than patients in the angle-closure hypertension or ACG suspect subtypes. PAS may be narrower in earlier stages and broader in later stages. PAS was also found most frequently in the superior part of the eye. The extent of synechial closure of the angle may play a role in raising IOP levels in later stages of the disease rather than early on.