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Randomized Controlled Trial
. 2020 Apr 28;9(5):22.
doi: 10.1167/tvst.9.5.22. eCollection 2020 Apr.

Histologic Changes Following Continuous Wave and Micropulse Transscleral Cyclophotocoagulation: A Randomized Comparative Study

Kareem Moussa  1 , Max Feinstein  1 , Melike Pekmezci  1   2 , Jun Hui Lee  1 , Michele Bloomer  1   2 , Catherine Oldenburg  1 , Zhimin Sun  1   3 , Richard K Lee  4 , Gui-Shuang Ying  5 , Ying Han  1
Affiliations
Randomized Controlled Trial

Histologic Changes Following Continuous Wave and Micropulse Transscleral Cyclophotocoagulation: A Randomized Comparative Study

Kareem Moussa et al. Transl Vis Sci Technol. .

Abstract

Purpose: To compare the macroscopic and microscopic histologic changes in eyes treated with micropulse transscleral cyclophotocoagulation (MP-TCP) versus continuous wave transscleral cyclophotocoagulation (CW-TCP).

Methods: Twelve halves of globes from three pairs of adult cadaveric eyes were randomly assigned to nontreated control, CW-TCP, single MP-TCP treatment, or double MP-TCP treatments, and then sectioned for histologic analysis. Presence or absence of the following four unique histologic changes was recorded: splitting within the ciliary process epithelium (splitting), separation of the pigmented ciliary process epithelium from the stroma (separation), coagulation of collagen and destruction of ciliary process stroma (coagulation), and full-thickness destruction of ciliary process epithelium (destruction).

Results: A total of 498 slides were analyzed, and laser scars in all treated specimens were located in the pars plana. Logistic regression analysis showed that compared with controls, CW-TCP-treated specimens were significantly more likely to experience separation (odds ratio [OR] = 11.1, P = 0.02), coagulation (OR = 24.3, P = 0.002), and destruction (OR = 11.1, P = 0.03). Destruction of the ciliary process epithelium was observed exclusively in CW-TCP-treated sections. No significant differences in histologic features were observed between controls and MP-TCP.

Conclusions: MP-TCP does not produce significant histologic changes in cadaveric eyes, whereas CW-TCP treatment does.

Translational relevance: These findings improve understanding of the mechanism of MP-TCP, help explain the increased rates of adverse effects following CW-TCP treatment compared with MP-TCP, and describe effects of MP-TCP at various doses.

Keywords: CW-TCP; MP-TCP; cyclophotocoagulation; histology.

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Conflict of interest statement

Disclosure: K. Moussa, None; M. Feinstein, None; M. Pekmezci, None; J.H. Lee, None; M. Bloomer, None; C. Oldenburg, None; Z. Sun, None; R.K. Lee, None; G.-S. Ying, None; Y. Han, None

Figures

Figure 1.
Figure 1.
Diagrammatic representation of processing of tissue specimens.
Figure 2.
Figure 2.
Representative images depicting histologic features included in the study. Hematoxylin and stained sections, 100x magnification. Green asterisk: splitting within the ciliary epithelium, between pigmented and nonpigmented epithelia; blue arrowhead: separation of the pigmented ciliary epithelium from the stroma; red arrowhead: coagulation of collagen and destruction of ciliary body stroma; green diamond: full-thickness destruction of ciliary epithelium. (A) Control, (B) double MP-TCP-treated eye, (C-D) CW-TCP-treated eyes.
Figure 3.
Figure 3.
Macroscopic changes following continuous wave and MP-TCP treatment in adult cadaveric eyes. The laser burns (blue arrow) are seen exclusively within the pars plana. Adult eye treated with CW-TCP (A and C). Adult eye treated with MP-TCP (B and D). Note the grossly evident tissue rupture in (C).
Figure 4.
Figure 4.
Percentage of sections demonstrating each histologic feature by treatment group. ***Indicates P < 0.001.
See this image and copyright information in PMC

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