Chenxing Zhang1, Matthew Bald1, Maolong Tang1, Yan Li1, David Huang2. 1. From the Center for Ophthalmic Optics & Lasers (Zhang, Bald, Tang, Li, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, USA; the Southwest Eye Hospital (Zhang), Third Military Medical University, Chongqing, China. 2. From the Center for Ophthalmic Optics & Lasers (Zhang, Bald, Tang, Li, Huang), Casey Eye Institute and Department of Ophthalmology, Oregon Health & Science University, Portland, Oregon, USA; the Southwest Eye Hospital (Zhang), Third Military Medical University, Chongqing, China. Electronic address: davidhuang@alum.mit.edu.
Abstract
PURPOSE: To evaluate the interface quality of different corneal lamellar-cut depths with the femtosecond laser and determine a feasible range of depth for femtosecond laser-assisted lamellar anterior keratoplasty. SETTING: Casey Eye Institute, Portland, Oregon, USA. DESIGN: Experimental study. METHODS: Full lamellar cuts were made on 20 deepithelialized human cadaver corneas using the femtosecond laser. The cut depth was 17% to 21% (100 μm), 31%, 35%, 38% to 40%, and 45% to 48% of the central stromal thickness. Scanning electron microscopy images of the cap and bed surfaces were subjectively graded for ridge and roughness using a scale of 1 to 5 (1 = best). The graft-host match was evaluated by photography and optical coherence tomography in a simulated procedure. RESULTS: The ridge score was correlated with the cut depth (P = .0078, R = 0.58) and better correlated with the percentage cut depth (P = .00024, R = 0.73). The shallowest cuts had the fewest ridges (score 1.25). The 31% cut depth produced significantly fewer ridges (score 2.15) than deeper cuts. The roughness score ranged from 2.19 to 3.08 for various depths. A simulated procedure using a 100 μm host cut and a 177 μm (31%) graft had a smooth interface and flush anterior junction using an inverted side-cut design. CONCLUSIONS: The femtosecond laser produced more ridges in deeper lamellar cuts. A depth setting of 31% stromal thickness might produce adequate surface quality for femtosecond laser-assisted lamellar anterior keratoplasty. The inverted side-cut design produced good edge apposition even when the graft was thicker than the host lamellar-cut depth. FINANCIAL DISCLOSURE: Proprietary or commercial disclosures are listed after the references.
PURPOSE: To evaluate the interface quality of different corneal lamellar-cut depths with the femtosecond laser and determine a feasible range of depth for femtosecond laser-assisted lamellar anterior keratoplasty. SETTING: Casey Eye Institute, Portland, Oregon, USA. DESIGN: Experimental study. METHODS: Full lamellar cuts were made on 20 deepithelialized human cadaver corneas using the femtosecond laser. The cut depth was 17% to 21% (100 μm), 31%, 35%, 38% to 40%, and 45% to 48% of the central stromal thickness. Scanning electron microscopy images of the cap and bed surfaces were subjectively graded for ridge and roughness using a scale of 1 to 5 (1 = best). The graft-host match was evaluated by photography and optical coherence tomography in a simulated procedure. RESULTS: The ridge score was correlated with the cut depth (P = .0078, R = 0.58) and better correlated with the percentage cut depth (P = .00024, R = 0.73). The shallowest cuts had the fewest ridges (score 1.25). The 31% cut depth produced significantly fewer ridges (score 2.15) than deeper cuts. The roughness score ranged from 2.19 to 3.08 for various depths. A simulated procedure using a 100 μm host cut and a 177 μm (31%) graft had a smooth interface and flush anterior junction using an inverted side-cut design. CONCLUSIONS: The femtosecond laser produced more ridges in deeper lamellar cuts. A depth setting of 31% stromal thickness might produce adequate surface quality for femtosecond laser-assisted lamellar anterior keratoplasty. The inverted side-cut design produced good edge apposition even when the graft was thicker than the host lamellar-cut depth. FINANCIAL DISCLOSURE: Proprietary or commercial disclosures are listed after the references.
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