Potential utility of anterior segment optical coherence tomography and biometry in differentiating plateau iris configuration from pupillary block.

Abstract

Clinical relevance: Angle closure glaucoma is one of the most common blinding diseases encountered mainly in older age groups, although it may also occur at a younger age. Identifying the underlying cause of angle closure helps in designing specific treatment strategies essential for effective disease management.

Background: Primary angle closure disease, caused due to pupillary block (PB) and plateau iris configuration (PIC), necessitates different management strategies. This study assessed the potential utility of anterior segment optical coherence tomography (ASOCT) and optical biometry in distinguishing PIC from PB in primary angle closure disease of the young (PACDy).

Methods: Patients aged 20-40 years with PACDy and age-matched healthy controls were recruited. Ophthalmic examinations included gonioscopy, ultrasound biomicroscopy, ASOCT, and biometry. Anterior chamber depth, lens thickness, axial length, central corneal thickness, lens position, relative lens position, vitreous cavity length, lens vault, relative lens vault and angle opening distance, trabecular iris space area, and trabecular iris angle were measured. Receiver operating characteristics curve analysis evaluated the discriminative ability of these parameters.

Results: Of the 280 eyes, 128 were normal and 152 had PACDy. Of 128 PACDy, 88 had PIC, and 64 had PB. Both PIC and PB had significantly smaller ASOCT and biometric parameters than normal eyes. However, PIC had intermediate biometric values that fell between normal eyes and PB. All the aforementioned parameters, except central corneal thickness, showed excellent discriminating ability of PIC and PB from normal eyes; however, no single parameter can strongly differentiate PB from PIC. Axial length and relative lens vault had the highest, although weak, power for discriminating PB from PIC.

Conclusion: ASOCT and biometry effectively distinguish PIC and PB from normal eyes, but no single parameter reliably differentiates PIC from PB. Comprehensive gonioscopy and ultrasound biomicroscopy may be necessary for accurate diagnosis in PACDy.