Aims To evaluate, using anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM), the uveo-scleral aqueous humour (AH) outflow pathways after ultrasonic circular cyclocoagulation (UCCC).
Methods Forty-four patients with refractory glaucoma underwent 4 or 6 s UCCC (group 1, 24 eyes; group 2, 20 eyes). UCCC was successful when the preoperative intraocular pressure (IOP) reduced by one-third. AS-OCT and IVCM were performed at baseline and at month 1 to evaluate the sclera and conjunctiva. The main outcomes were mean intra-scleral hyporeflective spaces area (MIHSA: mm2) at AS-OCT, mean density and area of conjunctival microcysts (MMD: cysts/mm2; MMA: µm2) at IVCM. The relations between MIHSA, MMA and MMD with IOP were analysed.
Results Mean baseline IOP was 26.9±2.8 mm Hg in group 1 and 27.5±4.0 in group 2. Intra-scleral hyporeflective spaces and microcysts were observed in both groups, without significant differences in MIHSA, MMA and MMD. At month 1, UCCC was successful in 63.6% of patients (41.6% in group 1, 80% in group 2), and IOP reduced to 18.8±3.2 (30.1%) and 17.1±2.7 mm Hg (38.7%), respectively (p<0.001). MIHSA showed a twofold and threefold increase in group 1 and 2 (p<0.05), with a significant difference between groups (p<0.05). MMA and MMD increased in both groups (p<0.05), with values higher in group 2 (p<0.05). Significant relations were found between MIHSA and IOP in both groups (p<0.01).
Conclusions UCCC induced anatomical modifications of sclera and conjunctiva, which suggested that the trans-scleral AH outflow enhancement is one of the possible mechanisms exploited by ultrasounds to reduce IOP.
- Aqueous humour
- Sclera and Episclera
- Treatment Surgery
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RM and LA contributed equally to this work and share primary authorship.
Contributors RM: writing the article; critical revision of the article. LA: conception and design; writing the article; critical revision of the article. VF: provision of patients; performing examinations; statistical contribution. LT: writing the article; performing examinations. LB: provision of patients; performing examinations; data collection. SDS: literature research; data collection. ED: literature research; critical revision of the article. GM: critical revision and final approval of the article.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Institutional Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement The present study contributed to clarifying the mechanism of action of ultrasonic cyclocoagulation in patients with refractory glaucoma. Particularly, we documented a scleral architecture rearrangement, which enhances trans-scleral aqueous humour drainage.