Abstract
PurposeTo determine the factors associated with retinal nerve fiber layer (RNFL) loss in eyes with acute primary angle-closure (APAC), particularly focusing on the influence of the change in the anterior lamina cribrosa surface depth (LCD).MethodsAfter the initial presentation, 30 eyes with unilateral APAC were followed up at the following specific time points over a 12-month period: 1 week, 1~2 months, 2~3 months, 5~6 months, and 11~12 months. These follow-ups involved intraocular pressure measurements, enhanced depth-imaging spectral-domain optical coherence tomography (SD-OCT) scanning of the optic disc, and measurements of the circumpapillary RNFL thickness. The prelaminar tissue thickness (PLT) and LCD were determined in the SD-OCT images obtained at each follow-up visit.ResultsRepeated measures analysis of variance revealed a significant pattern of decrease in the global RNFL thickness, PLT, and LCD (all p<0.001). The global RNFL thickness decreased continuously throughout the follow-up period, while the PLT decreased until 5~6 months and did not change thereafter. The LCD reduced until 2~3 months and then also remained steady. Multivariable regression analysis revealed that symptoms with a longer duration before receiving laser peripheral iridotomy (LI) (p = 0.049) and a larger LCD reduction (p = 0.034) were significant factors associated with the conversion to an abnormal RNFL thickness defined using OCT normative data.ConclusionEarly short-term decreases in the PLT and LCD and overall long-term decrease in the peripapillary RNFL were observed during a 12-month follow-up after an APAC episode. A longer duration of symptoms before receiving LI treatment and larger LCD reduction during follow-up were associated with the progressive RNFL loss. The LCD reduction may indicate a prior presence of significant pressure-induced stress that had been imposed on the optic nerve head at the time of APAC episode. Glaucomatous progression should be suspected in eyes showing LCD reduction after the APAC remission.
Highlights
Acute primary angle closure (APAC) is characterized by an acute, symptomatic intraocular pressure (IOP) increase followed by rapid recovery from the symptoms after applying timely treatment
Multivariable regression analysis revealed that symptoms with a longer duration before receiving laser peripheral iridotomy (LI) (p = 0.049) and a larger lamina cribrosa surface depth (LCD) reduction (p = 0.034) were significant factors associated with the conversion to an abnormal retinal nerve fiber layer (RNFL) thickness defined using OCT normative data
Short-term decreases in the prelaminar tissue thickness (PLT) and LCD and overall long-term decrease in the peripapillary RNFL were observed during a 12-month follow-up after an APAC episode
Summary
Acute primary angle closure (APAC) is characterized by an acute, symptomatic intraocular pressure (IOP) increase followed by rapid recovery from the symptoms after applying timely treatment. Changes in the optic nerve head (ONH) in APAC have been described as an initial swelling and hyperemia that resolves after applying timely treatment, or is followed by pallor of the optic disc with diffuse thinning of the axons when the acute episode leads to permanent sequelae in the ONH.[8,9,10] changes in the deep ONH tissues (i.e., prelaminar tissue or the lamina cribrosa [LC]) or peripapillary tissues (i.e., peripapillary choroid) after APAC are not well described. The interplay between the deep ONH tissues and axons has been considered a key to understanding the mechanism of glaucomatous optic neuropathy, which has prompted explorations of the deep ONH tissues including the LC.[11, 12] Numerous experimental and clinical studies have suggested that structural changes in the LC and peripapillary tissues have significant implications for glaucoma pathogenesis.[12,13,14,15,16,17,18,19,20,21,22,23] most of these studies have focused on open-angle glaucoma (OAG), with few investigating eyes with APAC[24] or suspected APAC diagnosed based on the darkroom-prone provocative test.[25]
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