Measurement of retinal nerve fiber layer in primary acute angle closure glaucoma by optical coherence tomography

To detect the objective structure changes of the retinal nerve fiber layer (RNFL) in primary acute angle closure glaucoma (PAACG) and to evaluate the efficacy of quantitative assessment of RNFL thickness with optical coherence tomography (OCT).

Forty patients who had unilateral PAACG attack in the first 4 months after remission and 40 single eyes from 40 normal controls were enrolled in this cross-sectional study. For all cases, PAACG had resolved after treatment. Using the Stratus OCT, the RNFL was assessed in both eyes within 2 weeks after PAACG, and again after 4 months. The OCT parameters were compared among normal controls, the unaffected fellow eyes, and the attacked eyes within 2 weeks and at 4 months after remission. Of the 40 patients, 14 PAACG patients underwent 5 times measurements, respectively, within 2 weeks and at 1, 2, 3, and 4 months after intraocular pressure was controlled. Differences between affected eyes and fellow eyes for the mean RNFL thickness at various periods after remission were also compared.

RNFL of the PAACG eyes became thicker (average: 142.6+/-22.9 microm) within 2 weeks and thinner (average: 83.6+/-19.8 microm) at 4 months after acute strike compared with the fellow unaffected and normal eyes. Significant differences were demonstrated comparing the average and 4-quadrant RNFL thicknesses for the attacked eyes with those of the normal controls (P<0.001 to 0.001) and fellow eyes (P<0.001 to 0.002) using 1-way analysis both within 2 weeks and at 4 months after remission. There was significant difference in the RNFL thickness among the 5 time points after intraocular pressure controlled in the acute strike group (P<0.001).

Using OCT, RNFL thickness was found to increase in eyes immediately after an episode of PAACG followed by a decrease in RNFL thickness over time (up to 3 mo). This detection can aid in better understanding the pathologic retinal changes involved in PAACG, and help in the assessment and management of these patients.