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Combined treatment of keratoconus: femtosecond-assisted intracorneal ring segment implantation, corneal collagen cross-linking and topography-guided PRK

Poster Details

First Author: D.Alexander RUSSIA

Co Author(s):    Y. Kishkin   E. Branchevskaya   S. Izmailova        

Abstract Details



Purpose:

To determine the efficacy of combined keratoconus treatment including Femtosecond- assisted intracorneal ring segments (ICRS) implantation, corneal collagen cross-linking (CXL) followed by topography-guided PRK to improve patient's visual functions and stop ectasia progression

Setting:

S. Fyodorov Eye Microsurgery Federal State Institution

Methods:

Prospective, non-comparative analysis of 46 cases. 46 eyes of 39 keratoconus patients received Femtosecond assisted (Zimmer FEMTO LDV, Ziemer Group, Switzerland) implantation of 160° arc-length half-moon shaped segments with inner diameter 5.0 mm and outer diameter 5.6mm (The S. Fyodorov Eye Microsurgery Federal State Institution Research Enterprise). Standard CXL procedure using 0.1% riboflavin and 20% dextran solution and UV-X 1000 illumination system (IROC AG, Zurich, Switzerland) was performed 6 months after ICRS implantation. Topography- guided PRK was performed at least 12 months after CXL. Inclusion criteria for PRK procedure were stable refraction at least 6 months after CXL, corneal thickness at thinnest point 450μm or more and contact lens intolerance. Transepithelial Topograpy-Guided PRK with maximum ablation depth up to 50μm was performed using MicroScan Visum exсimer laser (Optosystems, Troitsk, Russia). Ablation zone varied depending on pupil size and attempted correction. Postoperative assessments - uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal topography (Tomey TMS-4, Japan), Scheimpflug-tomography (Pentacam, Oculus, Germany) were performed at 1 week and 1, 3, 6 and 12 months after each surgical procedure.

Results:

Six months after ICRS implantation mean UDVA improved from 0.07±0.02 (range 0.05 - 0.1) to 0.12±0.04 (range 0.05 - 0.2) and CDVA from 0.32±0.08 (range 0.16 - 0.5) to 0.40±0.07 (range0.3-0.6). Mean spherical equivalent (SE) refraction decreased from -9.52±2.41D to-5.63±1.93D. All patients had significant decrease of anterior as well as posterior cornea central elevation values and increase of best fit sphere (BFS) radius of anterior cornea surface from 7.21±0.28mm to 7.59±0.14mm. At 6 month after CXL mean UDVA was 0.12±0.04 and mean CDVA 0.44±0.11. Mean refraction SE decreased to -5.02±1.85D. All eyes had further decrease of maximum anterior cornea elevation values, while posterior elevation data were unchanged. Six months after topography-guided PRK UDVA improved from 0.12±0.04 (range 0.05 - 0.2) to 0.47±0.16 (range 0.16 - 0.8) and CDVA from 0.44±0.11 (range 0.16 - 0.7) to 0.64±0.13 (range 0.32 to 0.9). Mean refraction SE decreased from -6.51±1.41D to -2.70±0.73D No eyes lost lines of CDVA. There were 5 cases of haze grade 0.5-1.0 formation at the periphery of ablated zone. 12 months after PRK mean value of posterior cornea elevation at thinnest point location were unchanged (pre op.-52.7±12.4μm and 50.2±14.1μm) as well as mean BFS radius 6.79mm pre op. and 6.82mm post op.

Conclusions:

Femtosecond assisted ICRS implantation is effective for remodeling and flattering corneal surface at first step of combined keratocous treatment. CXL procedure is effective for stabilizing cornea and refractive changes after ICRS implantation. Topography-guided PRK after ICRS implantation and corneal collagen cross-linking is effective for improving visual acuity in select patients. Primary results showed slight myopic shift of SE refraction at 6 till 12 months post op. just as in standard PRK for moderate - high myopia and stability of posterior cornea elevation data at this time. A larger study is needed to determine the long-term stability results of this combined treatment. FINANCIAL INTEREST: NONE

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