Jyoti Shetty1, Michelle Clovis Da Costa2, Jhanavi Jhamnani3, Fauqia4
BACKGROUND After trabeculectomy, wound remodelling and fibrosis continues lifelong and can affect bleb filtration. Ethnicity plays an important role in wound healing. Wound modulation with Mitomycin C affects the morphology as well as long-term functional success of the bleb.
The aim of the study is to assess the morphology of blebs 5 years post trabeculectomy using clinical methods (slit lamp biomicroscopy and Moorfields Bleb Grading System MBGS) along with Anterior Segment Optical Coherence Tomography (AS-OCT) and to correlate it with its functional outcome.
MATERIALS AND METHODS
This prospective cross-sectional study evaluated 40 eyes of 30 patients who had undergone trabeculectomy with adjuvant mitomycin C and had a postoperative duration of 5 years or more. Following a comprehensive ophthalmic examination, grading of filtering bleb was performed using MBGS. Internal bleb morphology was imaged using AS-OCT.
At the time of surgery, the age of the patients ranged from 33-71 years. The average postoperative duration was 8.6 ± 3.3 years. Based on slit lamp biomicroscopy, we found that 47% of the total blebs were diffuse, 30% were cystic and 23% were flat. MBGS parameters were studied in relation to bleb type on slit lamp. Bleb height (p=0.001) and central bleb vascularity (p=0.010) were found to have statistically significant association. There is a statistically significant agreement between the bleb type on slit lamp examination and morphological classification based on AS-OCT at p<0.05 (p=0.000). We observed complete success in 90% of eyes and qualified success in 100%. IOP at the time of study was found to have negative correlation with total bleb height on AS-OCT (r: -0.3592; p=0.022909).
This case series with a long-term followup period showed that trabeculectomy augmented with Mitomycin C (MMC) can achieve good long-term IOP control. The filtering bleb morphology using clinical methods (slit lamp biomicroscopy and MBGS) and AS-OCT was found to be consistent; therefore, indicating that clinical grading of bleb morphology is adequate and reliable in clinics in which imaging techniques are not available. In cases where IOP and bleb morphology do not correlate, AS-OCT is a useful tool to assess the internal bleb morphology and enhances our understanding of bleb functioning.