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International Journal of Bioprinting Amniotic fornical ring for ocular surface reconstruction

transplantation (AMT) promotes epithelialization by conjunctival sac sizes. The purpose of this retrospective
facilitating corneal and conjunctival cell migration. analysis is to collect related material and detailed clinical
Meanwhile, AMs can secrete several cytokines and inhibit information from enrolled patients. In particular, we explored
inflammation, scarring and angiogenesis . Since the the clinical indications of AFR and compared the outcomes
[2]
1940s, AM has been most commonly used in ocular surface with those of SAMT. Moreover, the cost-effectiveness was
reconstruction due to a variety of diseases, including analyzed between the SAMT and AFR groups.
chemical burns, pterygium, ocular surface neoplasia,
Steven–Johnson syndrome (SJS), and toxic epidermal 2. Materials and methods
necrolysis (TEN) .
[3]
2.1. Materials
The AM is only approximately 0.1 mm thick. The AM PLA 3DP Filament (diameter: 1.75 mm) was purchased
is so thin that it is prone to intraoperative tears and early from Sigma-Aldrich (USA). A HORI Z300 PLUS 3D
postoperative dissolution. Moreover, prolonged sutures printer was purchased from Huitianwei Technology Co.,
can induce conjunctival granulomas. ProKera, which is Ltd. (Beijing, China). Oxybuprocaine hydrochloride
a cryopreserved AM that is installed upon polycarbonate eye drops (0.4%, 20 mL, Santen, Japan) were used as a
ring systems, has been approved by the United States Food topical anesthetic. Lidocaine hydrochloride injection (2%,
and Drug Administration (U.S. FDA) . The advantages of Sinopharm Ronshyn Pharmaceutical Co., Ltd. China)
[4]
ProKera over traditional sutured AM are that there is no was used for infiltration anesthesia. Topical medications,
need for sutures or operating rooms, and it is easy to insert including eye gel of deproteinized calf blood extract (20%,
and remove. Zhou et al. reported that ProKera prolonged 5 g, Shenyang Xingqi Pharmaceutical Co., Ltd.), sodium
the dissolution time compared with that of sutured hyaluronate eye drops (0.1%, 10 mL, Germany), levofloxacin
AMT . If an extensive ocular surface injury occurs, eye drops (0.5%, Santen, Japan), gatifloxacin eye gel (0.3%,
[5]
the AM is required to cover the entire ocular surface, 5 g, Shenyang Xingqi Pharmaceutical Co., Ltd.), TobraDex
including the cornea, bulbar conjunctiva, palpebral eye drops (tobramycin 0.3% and dexamethasone 0.1%,
conjunctiva, conjunctival vault, and palpebral margin. 5 mL, Alcon, USA), TobraDex eye ointment (tobramycin
However, the ProKera device can only cover the cornea 0.3% and dexamethasone 0.1%, 3.5 g, Alcon, USA), and
and perilimbal conjunctiva. In addition, edema of the Tacrolimus eye drops (0.1%, Santen, Japan) were used to
conjunctiva and eyelids often occurs in the acute stage of promote epithelial repair, prevent infection, and alleviate
the disease, resulting in difficult exposure of the operative inflammation, respectively. A 10-0 nylon suture (Alcon,
field, prolonging the suture time, and increasing the risk of USA) was used to secure the amniotic membrane.
surgery for patients. Therefore, it is necessary to develop
a new device to facilitate AM fixation in the conjunctival 2.2. Fabrication of sterile AFR
vault or even cover the eyelid margin. The 3D-printed AFR was designed with Autodesk 123D
design software. The STL files were converted to the
In recent years, three-dimensional printing (3DP) gcode format using CURA software. PLA filaments were
technology has been widely applied in medicine and loaded into the 3D printer, melted at 210°C and extruded
include implants, medical instruments, prosthetics, and through a nozzle (0.4 mm) to print layer by layer. The layer
pharmaceutical products. 3DP has enormous potential in height and the printing speed were 0.2 mm and 60 mm/s,
fabricating customized, low-cost, and complex scaffolds . respectively. The wall thickness of the AFR is 0.8 mm.
[6]
3DP membranes, as an alternative to amniotic membranes, The transverse and longitudinal diameters of the AFR
have also been used for ocular surface or conjunctival defect are based on the size of the patients’ conjunctiva sac. The
reconstruction . Fused deposition modeling (FDM), which fabrication of the AFR is illustrated in Figure 1A. The AFR
[7]
is one of the most commonly used 3DPs, is a complex was sterilized with ethylene oxide before surgery. The acute
process, including drawing the solid filament into the printer phase of inflammation often leads to massive exudation in
head, melting in the heating zone, and extruding through the conjunctival sac. Therefore, in patients who are in the
the printer nozzle. FDM has several advantages, including acute phase, the AFR needs to be partially clipped to leave
flexibility, having a wide range of materials, being economical, a gap for exudates to drain (Figure 1A).
and personalized precision . Polylactic acid (PLA) has
[8]
become the most frequently utilized 3D-printed material 2.3. Description of technique
because of its low cost and relatively low melting point. Ethics approval was obtained from Henan Eye Hospital
Moreover, it has been approved as a biomedical material (Permit number: HNEEC-2022(53)). The institutional
due to its good biocompatibility . In the present study, we review board approved a retrospective medical review of
[9]
fabricated personalized amniotic fornical rings (AFRs) with patients, who underwent AFR and suture AMT (SAMT)
PLA materials by 3DP technology according to different for various ocular surface injuries between January 2019

Volume 9 Issue 3 (2023) 331 https://doi.org/10.18063/ijb.713