Fluorometholone

Preoperative peripheral iridotomies by neodymium - yttrium - aluminum - garnet (Nd:YAG) laser or intraoperative peripheral iridotomies were performed for ICL V4 implantations and no peripheral iridotomies were performed for ICL V4c implantations. On the day of surgery, all patients were administered with dilating and cycloplegic agents (2.5 % phenylephrine and 1 % tropicamide, Alcon, China). After topical anaesthesia (0.4 % oxybuprocaine hydrochloride, Santen, Japan) and injection of a viscoelastic surgical agent (1.7 % Sodium hyaluronate; Bausch & Lomb, China) into the anterior chamber, an ICL V4 IOL was inserted via a 2.8–3.2 mm temporal clear corneal incision with the use of an injector cartridge (STAAR Surgical). After the ICL was placed in the posterior chamber, the surgeon then completely removed the viscoelastic surgical agent from the eye using a balanced salt solution and instilled a miotic agent (0.005 % carbachol, Bausch & Lomb, China). All surgeries were uneventful and no intraoperative complications were observed. Following surgery, a combination antibacterial and steroidal medication (0.1 % Tobramycin dexamethasone, Alcon, China) was prescribed four times daily for 3 days followed by fluorometholone eyedrops tapered gradually over 2 weeks. Antibiotic eyedrops (0.5 % left Ofloxacin, Santen, Japan) were then prescribed four times daily for 1 week, along with non-steroidal anti-inflammatory eyedrops (NSAID, pranoprofen, Senju, Japan) four times daily for 2 weeks, and artificial tears four times daily for 1 month.

At least 1 week before ICL implantation, patients received two peripheral laser Nd:YAG iridotomies at 10:30 and 1:30 clock positions. On the day of surgery, 2.5% phenylephrine for mydriasis and 0.4% oxybuprocain hydrochloride eye drops were applied to the operative eye before surgery. All ICL/TICL implantations into the posterior chamber were performed with an injector cartridge designed by STAAR Surgical through a 3.2 mm corneal tunnel incision in the horizontal meridian using peribulbar anesthesia. The anterior chamber was filled with sodium hyaluronate 1% (Provisc), which was completely removed at the end of surgery. During TICL implantation, the surgeon marked the zero horizontal axis at the 3- and 9-o’clock limbus using a marking pen with the patient sitting upright at a slit lamp. The surgeon also used a Mendez ring to measure the required rotation from horizontal during the surgical procedure and the lens was rotated to the required axis using a modified intraocular spatula. Tobramycin eye drops were used four times a day for 7 days, 0.1% fluorometholone eye drops were instilled six times a day from the second day after surgery and minus one time every three days for one month.

All surgeries were performed by the same surgeon. Before the surgery, topical anesthetic eye drops were applied. After a lid speculum was used, a trephine (Model 52503B; 66 vision Tech Co, Ltd., Suzhou, China) was placed in the center of the cornea. ParaCel Solution (0.25% riboflavin-5-phosphate, hydroxylpropyl methylcellulose, NaCl, ethylenediaminetetraaceticacid, Tris, and benzalkonium chloride; Medio-Haus-Medizinprodukte GmbH, Kiel, Germany) was dripped into the trephine to cover the corneal epithelium for 4 min. The cornea was then continually infiltrated with Vibex-Xtra Solution (riboflavin phosphate 2.80 mg/mL and NaCl, Avedro, Inc.) for 6 min. After the cornea was rinsed with balanced salt solution (BBS), UV treatment was administered using Avedro’s KXL System (Avedro, Inc) for 5 min and 20 s with 365-nm UV-A light and 45 mW/cm2 irradiation in the pulsed mode (one second on, next second off). BBS was used to keep the ocular surface moist during irradiation. A bandage contact lens was applied after the procedure. Postoperative medications included levofloxacin (4 times daily for 1 week), 0.1% fluorometholone (7 times daily initially, then gradually reduced for 3 weeks), and artificial tears (4 times daily for 4 weeks).

All eyes were treated with the StreamLight® PRK software in WaveLight EX500 Excimer Laser (WaveLight®; Alcon Laboratories, Fort Worth, TX, USA). Postoperative emmetropia was targeted in all eyes and refractive correction was adjusted based on full cycloplegic refraction [13 (link), 14 (link)] with no specific nomograms used. After choosing the StreamLight profile, the epithelial ablation depth was determined based on epithelial mapping in a range between 45 and 65 μm (personal communication with Alcon recommends the use of maximum epithelial thickness) while the epithelial optical zone (OZ) in hyperopic corrections is 8.0 mm as a default setting. The stromal ablation OZ was set to the standard 6.5 mm for all eyes. The total ablation zone (which is a composite ablation zone for both the epithelial and stromal circles) was automatically adjusted to 8.9 mm for both the epithelial and stromal ablations to ensure epithelial-stromal ablation matching. Initially, a drop of a preservative-free local anesthetic was instilled followed by sterilizing the periocular skin and eyelashes with 10% povidone-iodine. An eyelid speculum was inserted and gentle wetting of the cornea with Merocel sponge (Medtronic Inc., Minneapolis, MN, USA) soaked with cold balanced salt solution (BSS, Alcon Lab., Fort Worth, TX, USA) followed by gentle drying was performed. Every patient was instructed to maintain their eye fixation on a green intermittent spotlight. The eye-tracker was activated, and laser ablation was focused and centered on the center of the pupil [15 (link)]. Stream excimer laser firing was started to remove the epithelium followed by stromal ablation in a single step. The manufacturer recommends a momentary stop for 10 s on hearing 3 pop sounds marking the transition between epithelial and stromal ablations to cool down the cornea. Mitomycin C (0.02%) [16 (link), 17 (link)] was applied mid-peripherally for 60 s followed by irrigating the stroma copiously with cold BSS. A soft bandage contact lens was applied until complete epithelial regeneration. An additional movie file shows the surgical steps in more detail (see Additional file 1). Postoperative medications included Moxifloxacin 0.5% eye drops 4 times daily for a week, Fluorometholone 0.1% eye drops twice daily for a month, preservative free artificial tears 5 times daily for 3 months and oral non-steroidal anti-inflammatory pills for post-PRK pain. One surgeon (MA) performed all the TE-PRK surgeries in the study.

LVC was performed by the same experienced operator (LH). The VisuMax femtosecond laser (Carl Zeiss Meditec AG, Jena, Germany) was utilized during the SMILE procedure. It involved removing a stromal lenticule, with a 110 µm-thick cap. For FS-LASIK, the lamellar flap with a superior hinge was created by a femtosecond laser (Ziemer Ophthalmic Systems AG, Port, Switzerland). The maximum thickness ranged from 90 to 110 µm. Tissue ablation was then performed using an Amaris 750 Hz excimer laser (Schwind eye-tech-solutions, Kleinostheim, Germany). Both groups received one drop of tobramycin/dexamethasone (Tobradex) shortly after surgery. A bandage contact lens (Oasys; Johnson & Johnson Vision, Santa Ana, USA) was placed on the cornea after FS-LASIK surgery. Sodium hyaluronate 0.1% (Hylo-comod) and topical fluorometholone 0.1% were then used 4 times a day for one week. The fluorometholone dosage was tapered each subsequent week until termination one month, while the Hylo-comod dosage remained unaltered.

Patients were instructed to wear plastic shields for 7 nights. The standard postoperative treatment was levofloxacin eye drops (Cravit; Santen Pharmaceutical Co., Ltd., Osaka, Japan) 4 times a day after surgery for 7 days, fluorometholone eye drops (Santen Pharmaceutical Co., Ltd., Osaka, Japan) at 0.1% 4 times a day for 2 weeks, and preservative-free artificial tears 4 times a day for a month. The patients were followed up at 1 day, 1 week and 1 month, and 3 months; the optometry, visual acuity, and IOP were examined at each visit. Pentacam scanning was performed at the 1-day, 1-month, and 3-month postoperative visits.