Abstract
Purpose: :
To measure the change in anterior chamber (AC) angle morphology after argon laser peripheral iridoplasty (ALPI) using anterior segment optical coherence tomography (ASOCT).
Methods: :
This was a retrospective study of patients with chronic angle closure who underwent ALPI in the year 2006. All patients had dark irides. The laser spot diameter used was either 50µm or 100µm. The power and duration of laser shots were modulated in each case to achieve AC deepening, small gas bubble formation, and localized iris tissue contraction. Imaging of nasal and temporal AC angles was performed with the ASOCT prototype (Carl Zeiss Meditec, Dublin CA, USA) before and no later than 4 weeks after ALPI. The angle opening distance at 500 µm (AOD500) and 750 µm (AOD750), AC depth, pupil diameter in the dark and corneal thickness were quantified from the ASOCT images. Eyes were assessed clinically for best corrected visual acuity (BCVA), intraocular pressure (IOP) and complications after ALPI .
Results: :
10 patients were included with a mean age of 62.4 ± 7.0 years. All (100%) were Asian and 4 were men (40%). In the dark, there was an increase in the mean temporal AOD500 (0.013 ± 0.042 vs. 0.078 ± 0.060 µm, p=0.007), no increase in the mean nasal AOD500 (0.036 ± 0.060 vs. 0.059 ± 0.063 µm, p=0.092), an increase in the mean nasal AOD750 (0.073 ± 0.084 vs. 0.151 ± 0.072 µm, p=0.010) and an increase in the mean temporal AOD750 (0.074 ± 0.072 vs. 0.155 ± 0.083 µm, p=0.012) after ALPI. In the light, there was an increase in the mean nasal AOD 750 (0.111 ± 0.090 vs. 0.183 ± 0.081 µm, p=0.002), but no increase in the mean nasal AOD500, (0.065 ± 0.073 vs. 0.084 ± 0.055 µm, p=0.226), the mean temporal AOD500 (0.049 ± 0.066 vs. 0.096 ± 0.069 µm, p=0.116) or the mean temporal AOD750 (0.140 ± 0.076 vs. 0.191 ± 0.081 µm, p=0.087). There was an increase in the mean AC depth after ALPI (2.031 ± 0.254 vs. 2.065 ± 0.283 mm, p=0.048). There was no change in the mean IOP (14.90 ± 4.38 vs. 15.40 ± 3.17 mmHg, p=0.663) or the mean number of ocular hypotensive medications (1.00 ± 0.82 to 0.50 ± 0.53, p=0.052) after ALPI. There was no change in BCVA (0.15 ± 0.12 vs. 0.17 ± 0.13 logMAR units, p=0.370), the mean pupil diameter in the dark (4.337 ± 0.521 vs. 4.240 ± 0.417 mm, p=0.335) or the mean corneal thickness (0.579 ± 0.026 vs. 0.579 ± 0.035 mm, p=1.000) after ALPI. One eye (10%) developed pigment dispersion after ALPI without raised IOP.
Conclusions: :
In this study, a change in AC angle morphology after ALPI was demonstrated using ASOCT. A larger prospective series is indicated to investigate the effect of ALPI on long term outcomes.
Keywords: anterior segment • imaging/image analysis: clinical • laser