Tissue Responses and Wound Healing following Laser Scleral Microporation for Presbyopia Therapy

Abstract

To investigate the postoperative inflammatory and wound-healing responses after laser scleral microporation for presbyopia. Methods: Thirty porcine eyes were used for the optimization of laser intensities first. Six monkeys (12 eyes) received scleral microporation with an erbium yttrium aluminum garnet (Er:YAG) laser, and half of the eyes received concurrent subconjunctival collagen gel to modulate wound-healing response. The intraocular pressure (IOP) and the laser ablation depth were evaluated. The animals were euthanized at 1, 6, and 9 months postoperatively. The limbal areas and scleras were harvested for histologic analysis and immunofluorescence of markers for inflammation (CD11b and CD45), wound healing (CD90, tenascin-C, fibronectin, and HSP47), wound contraction (α-smooth muscle actin [α-SMA]), vascular response (CD31), nerve injury (GAP43), and limbal stem cells (P63 and telomerase). Results: In the nonhuman primate study, there was a significant reduction in IOP after the procedure. Overall, the ablation depth was 76.6% to 81.2% at 1 month and slightly decreased to 71.5% to 72.7% at 9 months. Coagulative necrosis around the micropores, as well as expression of CD11b, CD45, tenascin, fibronectin, HSP47, and GAP43, was distinct at 1 month but subsided with time. Collagen gel treatment significantly suppressed the upregulation of CD11b, CD45, fibronectin, and tenascin-C. The expression of CD90, α-SMA, and CD31 was minimal in all eyes. Conclusions: The study demonstrated the course of inflammatory and wound-healing responses following laser scleral microporation. The tissue responses were small and self-limited, resolved with time, and were suppressed by concurrent collagen treatment. It provides a useful understanding of this new procedure. Translational Relevance: The results would be helpful in the laser parameter modification to improve the long-term treatment stability.

Improvement in Accommodation and Dynamic Range of Focus After Laser Scleral Microporation: A Potential Treatment for Presbyopia

“…The technique of subconjunctival implantation of collagen matrix was detailed in a previous study. 22 The rationale for using the subconjunctival collagen was to determine its modulating effect on postoperative wound healing, which could affect the efficacy of LSM. At the conclusion of procedure, topical TobraDex ointment (Alcon, Fort Worth, TX, USA) was applied to both eyes twice daily for one week.…”

“…The surgical technique of LSM was described in a previous study. 22 Briefly, the LSM treatment was performed using an Er:YAG laser (VisioLite Gen I MP) with the following laser parameters: (a) frequency of 100 to 300 hz, (b) fluence of 0.9 to 1.5 W, (c) spot size of 225 µm, and (d) micropore depth of approximately 70% to 90% of sclera. The laser parameters, including the depth of the laser micropores, were previously optimized using an ex vivo porcine model.…”

“…The laser parameters, including the depth of the laser micropores, were previously optimized using an ex vivo porcine model. 22 Anterior segment optical coherence tomography was used to measure scleral thickness before surgery. The treatment thickness was 85% of the scleral thickness, and the pulse-per-pore was calculated using the following equation: “Treatment thickness/45.88 = pulse per pore.” The laser depth was subsequently confirmed on histology postmortem.…”

“…The zones were defined as follows: (1) zone 0: 0.0 to 1.3 mm from anatomical limbus; distance from the limbus to the superior boundary of ciliary muscle/scleral spur; (2) zone 1: 1.3 to 2.8 mm from limbus; distance from the sclera spur to the inferior boundary of the circular muscle; (3) zone 2: 2.8 to 4.7 mm from limbus; distance from the inferior boundary of the circular muscle to the inferior boundary of the radial muscle; (4) Zone 3: 4.7 to 6.6 mm from limbus; inferior boundary of the radial muscle to the superior boundary of the posterior vitreous zonule zone; and (5) zone 4: 6.6 to 7.3 mm from limbus; superior boundary of the posterior vitreous zonule zone to the superior boundary of the ora serrata. 22 Characteristics of the micropores are demonstrated in Figure 2 . All the procedures were performed by an experienced surgeon (J.S.M.).…”

“…In this preclinical study, we aimed to examine the accommodative changes in non-human primates, the macaque monkeys, which are the ideal animal model for the human eye for accommodation, after LSM for correcting presbyopia. We also evaluated the effects of concurrent subconjunctival collagen treatment on the treatment efficacy because our previous study showed that subconjunctival collagen treatment could improve scleral wound healing after LSM, 22 which may have an impact on the treatment efficacy.…”