Publications by authors named "Ivan N Chen"

2 Publications

  • Page 1 of 1

Predictability and stability of laser-assisted subepithelial keratectomy with mitomycin C for the correction of high myopia.

Medicine (Baltimore) 2017 Jun;96(22):e7076

Department of Ophthalmology, The University of Hong Kong, Grantham Hospital Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong.

The purpose of this study was to evaluate the predictability and stability of laser-assisted subepithelial keratectomy (LASEK) with mitomycin C (MMC) in correction of high myopia (≤-6.0 diopters [D]) as compared to low-to-moderate myopia (>-6.0 D).This is a retrospective, comparative, cohort study which included 43 eyes of 43 consecutive patients who underwent LASEK with MMC in a private hospital in Hong Kong by a single surgeon. Twenty-five eyes had high myopia (mean spherical equivalent [SE] = -8.53 ± 1.82 D) and 18 eyes had low-to-moderate myopia (mean SE = -3.99 ± 1.37 D) before surgery.In terms of refractive predictability, mean SE was significantly better in eyes with preoperative low-to-moderate myopia than high myopia at 6 months (0.04 ± 0.23 vs 0.31 ± 0.52 D, P = .035). In terms of refractive stability, between 1 and 3 months, both groups had mean absolute change of SE of around 0.25 D. Between 3 and 6 months, preoperative low-to-moderate myopia group had significantly less absolute change of SE compared to high myopia group (0.07 vs 0.23 D, P = .003). More eyes with preoperative high myopia changed SE by more than 0.25 D than those with low-to-moderate myopia between 3 and 6 months (32.0% vs 5.6%, P = .057).In conclusion, LASEK with MMC is more unpredictable and unstable in correction of high myopia than low-to-moderate myopia. The refractive outcome of most low-to-moderate myopia correction stabilizes at 3 months. Stability is not achieved until after 6 months in high myopia correction.
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http://dx.doi.org/10.1097/MD.0000000000007076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459740PMC
June 2017

Initial evaluation of a femtosecond laser system in cataract surgery.

J Cataract Refract Surg 2014 Jan 22;40(1):29-36. Epub 2013 Nov 22.

From the Department of Ophthalmology, Hong Kong Sanatorium and Hospital, Hong Kong Special Administrative Region, China.

Purpose: To report the early experience and complications during cataract surgery with a noncontact femtosecond laser system.

Setting: Hong Kong Sanatorium and Hospital, Hong Kong Special Administrative Region, China.

Design: Retrospective case series.

Methods: All patients had anterior capsulotomy or combined anterior capsulotomy and lens fragmentation using a noncontact femtosecond laser system (Lensar) before phacoemulsification. Chart and video reviews were performed retrospectively to determine the intraoperative complication rate. Risk factors associated with the complications were also analyzed.

Results: One hundred seventy eyes were included. Free-floating capsule buttons were found in 151 eyes (88.8%). No suction break occurred in any case. Radial anterior capsule tears occurred in 9 eyes (5.3%); they did not extend to the equator or posterior capsule. One eye (0.6%) had a posterior capsule tear. No capsular block syndrome developed, and no nuclei were dropped during irrigation/aspiration (I/A). Anterior capsule tags and miosis occurred in 4 eyes (2.4%) and 17 eyes (10.0%), respectively. Different severities of subconjunctival hemorrhages developed in 71 (43.8%) of 162 eyes after the laser procedure. The mean surgical time from the beginning to the end of suction was 6.72 minutes ± 4.57 (SD) (range 2 to 28 minutes).

Conclusions: Cataract surgery with the noncontact femtosecond laser system was safe. No eye lost vision because of complications. Caution should be taken during phacoemulsification and I/A to avoid radial anterior capsule tears and posterior capsule tears.
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http://dx.doi.org/10.1016/j.jcrs.2013.08.045DOI Listing
January 2014