New refractive method for laser thermal keratoplasty with the Co:MgF2 laser

Horn, Gerald; Spears, Kenneth G.; Lopez, Osvaldo I.; Lewicky, Andrew; Yang, Xueyu; Riaz, Muhammad; Wang, Renyan; Silva, Daisy; Serafin, Jenifer

doi:10.1016/s0886-3350(13)80779-1

Cited by 30 publications

(3 citation statements)

References 7 publications

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“…17(a)). Seiler and others [36]- [38] recently demonstrated that the refractive power of the cornea can be adjusted by shrinkage of corneal collagen fibers with lasers emitting around 2 pm [39]. A small series of hyperopic patients treated with the holmium laser coupled to a fiber-optic probe delivery system has shown reasonable predictability and fair stability of the refractive outcome.…”

Section: B Laser Photothermal Keratoplasty (Lptk) or Photoshrinkingmentioning

confidence: 99%

Therapeutic and diagnostic application of lasers in ophthalmology

Thompson

Ren²,

Parel³

1992

Proc. IEEE

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The accessibility of the human eye, its transparency and the absorption properties of its internal tissues have fostered a rapid evolution of applications for lasers in ophthalmology. Lasers are in ubiquitous clinical use for many therapeutic and diagnostic purposes and their application has become the standard of care in the treatment of many eye diseases including diabetic retinopathy, vascular disease, glaucoma, and the treatment of capsular opacification following cataract surgery. The success of laser therapy for eye diseases has been one of the most remarkable success stories in medicine. Millions of patients have had vision preserved or restored through laser treatment. Many new laser applications are under investigation, including refractive surgery, removal of cataracts, vitrea-retinal surgery, and diagnostic studies. Lasers achieve their effects in the eye through photothermal, photodisruptive, or photochemical mechanisms. Herein, we provide an overview of the present status of clinical and research applications for lasers in ophthalmology.

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Section: B Laser Photothermal Keratoplasty (Lptk) or Photoshrinkingmentioning

confidence: 99%

Therapeutic and diagnostic application of lasers in ophthalmology

Thompson

Ren²,

Parel³

1992

Proc. IEEE

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“…Later, other authors [4,5,6,9,15] described treatments for keratoconus. Fyodorov and Caster [3] were the first to apply an invasive method: a retractable steel needle, heated to 600C, was inserted deep into the corneal stroma.…”

Section: Introductionmentioning

confidence: 99%

Holmium:YAG thermokeratoplasty: treatment parameters for astigmatism induction based upon spherical enucleated human eyes

Bende

Jean

Derse

et al. 1998

Graefe's Arch Clin Exp Ophthalmol

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“…The ideal laser source for LTK should provide a uniform and continuous heating 10 within the irradiated volume down to the '-posterior stroma in order to apply a constant optimal temperature for cornea! shrinkage -- temperature8.…”

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confidence: 99%

<title>Laser thermokeratoplasty by means of a continuously emitting laser diode in the mid IR</title>

et al. 1996

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Laser thermokeratoplasty (LTK) has been performed with a continuously emitting, tunable laser diode at 1.86 jim. A study on enucleated porcine eyes was conducted in order to demonstrate the feasibility of this laser source for LTK and to determine the useful irradiation modalities. Refractive changes achieved with different application systems and a standard coagulation pattern, consisting of 8 coagulation spots on a 6 mm ring, were measured. The most promising sets of parameters were carrried out in a first animal study with mini pigs. Initial refractive changes up to 6 D could be achieved in vitro and in vivo with laser powers between 120 mW and 200 mW and irradiation times of several seconds. In conclusion, the mid-JR laser diode operated at a wavelength of 1.86 tm seems to be the optimal source for a clinical LTK system. key words: coagulation, collagen shrinkage, cornea, denaturation, hyperopia, refractive change, temperature calculation 1 . INTRODUCTIONLaser thermokeratoplasty (LTK) is a minimally invasive treatment for hyperopia and astigmatism. The increase in refractive power is achieved by thermally induced shrinkage of stromal collagen in the corneal periphery'3. For a spherical correction, typically 8 coagulations are equidistantely applied around the corneal center with a diameter between 5 and 8 mm. The resulting zone of annular stress is believed to increase the central corneal curvature. In order to treat hyperopic astigmatisms asymmetric patterns concentrated on the lower hyperopic, flat meridian can be used4.A variety of different laser sources and application systems have been investigated for LTK. Early attempts have been made with the Er:Glass laser (X=1.54 jim)', but also CO2 lasers (?.=9.6-10.6 jim)2 have been used. Currently the pulsed holmium laser system (A=2. 1 jim) is favorized due to the fact, that its wavelength has a penetration depth in the order of the corneal thickness, which allows coagulations deep into the corneal stroma. Two different holmium based laser systems are under phase II FDA approval:The first system (Sunrise Techn. Inc.) simultaneously applies the desired number of coagulations on the cornea in a non contact mode via slit lamp using collinear beams of about 600 tm in diameter. Mild hyperopic corrections of about +1 D were reported in the long term follow up of two years5. The advantage of this system, coupled to a slit lamp, is its non contact and very precise application of all coagulation at one time.The second system (Summit Techn. Inc.) uses a handpiece with a lens at the distal fiber tip to focus the radiation into the corneal stroma3'4'6. With this device deeper coagulations and a more homogeneous temperature distribution can be achieved. Patients treated here show a refractive change of +2-3 D change in the long term of one to two years6. For both systems a strong regression within the first 3 months post-op and a slower gradual regression in the following 6-18 months was reported6. 66 /SPIE Vol. 2930 0-8194-2332-7/96/$6.0Q Downloaded From: http://proceeding...

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New refractive method for laser thermal keratoplasty with the Co:MgF2 laser

Cited by 30 publications

References 7 publications

Therapeutic and diagnostic application of lasers in ophthalmology

Therapeutic and diagnostic application of lasers in ophthalmology

Holmium:YAG thermokeratoplasty: treatment parameters for astigmatism induction based upon spherical enucleated human eyes

<title>Laser thermokeratoplasty by means of a continuously emitting laser diode in the mid IR</title>

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