MD334Z - Method for laser correction of high myopia with insufficient corneal thickness - Google Patents

Method for laser correction of high myopia with insufficient corneal thickness Download PDF

Info

Publication number
MD334Z
MD334Z MDS20100189A MDS20100189A MD334Z MD 334 Z MD334 Z MD 334Z MD S20100189 A MDS20100189 A MD S20100189A MD S20100189 A MDS20100189 A MD S20100189A MD 334 Z MD334 Z MD 334Z
Authority
MD
Moldova
Prior art keywords
corneal
thickness
flap
ablation
cornea
Prior art date
Application number
MDS20100189A
Other languages
Romanian (ro)
Inventor
Irina Vrabii
Original Assignee
Irina Vrabii
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Irina Vrabii filed Critical Irina Vrabii
Priority to MDS20100189A priority Critical patent/MD334Z/en
Publication of MD334Y publication Critical patent/MD334Y/en
Publication of MD334Z5 publication Critical patent/MD334Z5/en
Publication of MD334Z publication Critical patent/MD334Z/en

Links

Landscapes

  • Laser Surgery Devices (AREA)

Abstract

The invention relates to medicine, in particular ophthalmology and can be used for laser correction of myopia and myopic astigmatism with insufficient corneal thickness by using the LASIK method.The method for laser correction of high myopia with insufficient corneal thickness consists in that after the local anesthesia and application of blepharostat it is marked the cornea, then with a mechanical microkeratom is formed a corneal pedicle flap from the nasal part of a thickness of 70…90 microns and a diameter of 8…9.5 mm. Then the corneal flap is pushed in the nasal part. It is carried out the aspherical ablation of corneal bed stroma with the excimer laser in the mode of flying spot of a diameter of 0.67 mm with a power of 120 mJ/cm2 and a frequency of 200 Hz, afterwards the corneal flap is placed on the initial location.

Description

Invenţia se referă la medicină, în special la oftalmologie şi poate fi utilizată pentru corecţia cu laserul a miopiei şi a astigmatismului miopic în caz de cornee subţire prin folosirea metodei LASIK. The invention relates to medicine, in particular to ophthalmology and can be used for laser correction of myopia and myopic astigmatism in case of thin corneas by using the LASIK method.

Se cunoaşte metoda de corecţie cu laserul cu eximeri a miopiei de grad mediu şi înalt în caz de cornee subţire, care constă în aceea că cu ajutorul microkeratomului se efectuează disecţia lamelară a lamboului cornean superficial cu picioruş cu grosimea de 130...160 µm. Se efectuează ablaţia stromei cu raze laser până la remodelarea formei necesare a corneei în aşa fel ca grosimea stromei reziduale după intervenţie să fie de cel puţin 250...300 µm. Repoziţionarea lamboului cornean. Peste 3 luni cu ajutorul microscopiei confocale se determină mărimea interfeţei, grosimea epiteliului în centrul corneei şi grosimea lamboului cornean. Datele obţinute se arhivează. Peste 6 luni se efectuează examinarea repetată cu determinarea aceloraşi mărimi şi se compară aceste măsurări. În cazul depistării îngustării interfeţei cu cel mult 10 µm, în lipsa măririi grosimii epiteliului şi a lamboului cornean se efectuează ablaţia cu laserul cu eximeri a stratului epitelial până la membrana Bowman. Apoi se efectuează ablaţia stromei lamboului cornean pentru remodelarea formei necesare. Adâncimea ablaţiei stromei lamboului cornean P se calculează după formula: The method of excimer laser correction of medium and high myopia in case of thin cornea is known, which consists in performing lamellar dissection of the superficial corneal flap with a pedicle with a thickness of 130...160 µm using a microkeratome. Stroma ablation is performed with laser beams until the necessary shape of the cornea is remodeled in such a way that the residual stroma thickness after the intervention is at least 250...300 µm. Repositioning of the corneal flap. After 3 months, the size of the interface, the thickness of the epithelium in the center of the cornea and the thickness of the corneal flap are determined using confocal microscopy. The obtained data are archived. After 6 months, a repeated examination is performed with the determination of the same sizes and these measurements are compared. If the interface narrowing is detected by no more than 10 µm, in the absence of an increase in the thickness of the epithelium and the corneal flap, excimer laser ablation of the epithelial layer up to Bowman's membrane is performed. Then the corneal flap stroma is ablated to remodel the required shape. The depth of corneal flap stroma ablation P is calculated according to the formula:

unde Ggr. este grosimea lamboului cornean, Gepit. - grosimea stratului epitelial [1]. where Ggr. is the thickness of the corneal flap, Gepit. - the thickness of the epithelial layer [1].

Metoda cunoscută are următoarele dezavantaje: se efectuează în câteva etape, ceea ce duce la tratarea îndelungată şi la cheltuieli financiare, este destul de complicat de realizat, lamboul cornean modelat (130...160 µm) în mare măsură dereglează proprietăţile biomecanice ale corneei, sporeşte riscul apariţiei ectaziei corneene postoperatorii, nu permite soluţionarea pe deplin a problemei de corecţie a miopiei de grad înalt în caz de cornee subţire (grosimea de cel puţin 500 µm). The known method has the following disadvantages: it is performed in several stages, which leads to long treatment and financial expenses, it is quite complicated to perform, the modeled corneal flap (130...160 µm) greatly disrupts the biomechanical properties of the cornea, increases the risk of postoperative corneal ectasia, and does not allow for the full solution of the problem of correcting high-grade myopia in the case of a thin cornea (thickness of at least 500 µm).

Problema pe care o rezolvă invenţia dată constă în simplificarea metodei, precum şi reducerea complicaţiilor postoperatorii. The problem solved by this invention consists in simplifying the method, as well as reducing postoperative complications.

Problema se soluţionează prin aceea că după anestezia topică şi aplicarea blefarostatului se marchează corneea, apoi cu un microkeratom mecanic se formează un lambou cornean pe picioruş de partea nazală cu grosimea de 70…90 µm şi diametrul de 8…9,5 mm. După aceasta lamboul cornean se deplasează în partea nazală. Se efectuează ablaţia asferică a stromei lojei corneene cu laserul cu eximeri în regimul spotului volant cu diametrul de 0,67 mm la o putere de 120 mJ/cm2 şi frecvenţă de 200 Hz, după care lamboul cornean se repune la locul iniţial. The problem is solved by marking the cornea after topical anesthesia and applying the blepharostat, then using a mechanical microkeratome, a corneal flap is formed on the pedicle on the nasal side with a thickness of 70…90 µm and a diameter of 8…9.5 mm. After that, the corneal flap is moved to the nasal side. Aspheric ablation of the corneal lodge stroma is performed with the excimer laser in the flying spot mode with a diameter of 0.67 mm at a power of 120 mJ/cm2 and a frequency of 200 Hz, after which the corneal flap is returned to its original place.

Formarea unui lambou cornean cu grosimea de 70...90 µm şi diametrul de 8...9,5 mm permite de a efectua intervenţia chirurgicală la pacienţii care până acum se considerau neoperabili sau se efectua corecţia cu o miopie restantă planificată de grad mediu şi înalt, sau se efectua corecţia intraoculară (se implanta un cristalin artificial, deoarece nu era suficient ţesut cornean pentru a face ablaţia cu laserul). Păstrarea grosimii suficiente a stromei reziduale împiedică apariţia ectaziei corneene postoperatorii. Pe lângă aceasta, adeziunea mai strânsă a lamboului cornean cu grosimea de 70...90 µm la patul stromal, faţă de lamboul cornean cu grosimea mai mare de 130 µm, duce la micşorarea riscului de adaptare insuficientă a lamboului în perioada postoperatorie. De aceea adaptarea mai rapidă a lamboului, alipirea mai bună a lui de patul stromal duce la o restabilire mai rapidă a funcţiilor vizuale. La efectuarea ablaţiei în straturile superficiale ale stromei (deoarece lamboul este ultrafin), unde structura stromei este mai densă şi mai compactă - proprietăţile biomecanice ale corneei se dereglează mai puţin, edemul stromei în perioada postoperatorie nu se dezvoltă. Păstrarea stromei reziduale suficiente (300 µm şi mai mult) permite în caz de necesitate (regresia efectului refractiv) de a efectua corecţia repetată (reablaţia). Efectuarea ablaţiei în straturile superficiale ( sub membrana Bowman) contribuie la o restabilire mai rapidă a plexului nervos subepitelial şi la apariţia mai rară a sindromului de ochi uscat. The formation of a corneal flap with a thickness of 70...90 µm and a diameter of 8...9.5 mm allows for surgical intervention in patients who were previously considered inoperable, or for correction of a planned residual myopia of medium and high degree, or for intraocular correction (an artificial lens is implanted, since there was not enough corneal tissue to perform laser ablation). Maintaining a sufficient thickness of the residual stroma prevents the occurrence of postoperative corneal ectasia. In addition, the tighter adhesion of the corneal flap with a thickness of 70...90 µm to the stromal bed, compared to the corneal flap with a thickness of more than 130 µm, leads to a decrease in the risk of insufficient adaptation of the flap in the postoperative period. Therefore, faster adaptation of the flap, its better adhesion to the stromal bed leads to a faster restoration of visual functions. When performing ablation in the superficial layers of the stroma (since the flap is ultrathin), where the structure of the stroma is denser and more compact - the biomechanical properties of the cornea are less disturbed, stromal edema in the postoperative period does not develop. Preservation of sufficient residual stroma (300 µm and more) allows, if necessary (regression of the refractive effect), to perform repeated correction (reablation). Performing ablation in the superficial layers (under Bowman's membrane) contributes to a faster restoration of the subepithelial nerve plexus and to a rarer occurrence of dry eye syndrome.

Crearea lamboului cu picioruş nazal permite de a păstra intacte o mare parte de fibre nervoase ale corneei ( majoritatea fibrelor anatomic sunt situate în cornee sub formă de fascicule, care se află în partea nazală şi temporală), care participă în continuare la reinervarea postoperatorie a corneei; de asemenea permite de a corecta mai deplin astigmatismul direct, care se întâlneşte mai frecvent (deoarece balamaua lamboului, mai ales baza lui nu încurcă); oferă posibilitatea de a efectua corecţia la pacienţii cu structura deosebită a scheletului facial (cu arcadele supraorbitale proeminente), ce practic e imposibil de efectuat cu microkeratomul, care formează picioruşul superior ( tehnica cu picioruş superior). The creation of the nasal pedicle flap allows to keep intact a large part of the corneal nerve fibers (most of the fibers are anatomically located in the cornea in the form of bundles, which are located in the nasal and temporal parts), which further participate in the postoperative reinnervation of the cornea; it also allows to more fully correct direct astigmatism, which is more common (since the flap hinge, especially its base, does not interfere); it offers the possibility of performing the correction in patients with a special structure of the facial skeleton (with prominent supraorbital arches), which is practically impossible to perform with the microkeratome, which forms the upper pedicle (upper pedicle technique).

Rezultatul invenţiei este micşorarea zonei şi a adâncimii de ablaţie şi majorarea ţesutului cornean rezidual. Aceasta se obţine prin micşorarea diametrului zonei centrale de ablaţie (mm) şi a puterii optice relative marginale a lentilei (un.rel.). În urma acestor transformări se micşorează adâncimea ablaţiei, precum şi durata efectuării ablaţiei, se schimbă numărul de impulsuri şi se păstrează ţesutul cornean rezidual suficient (µm). The result of the invention is the reduction of the ablation area and depth and the increase of the residual corneal tissue. This is achieved by reducing the diameter of the central ablation area (mm) and the marginal relative optical power of the lens (un.rel.). As a result of these transformations, the ablation depth is reduced, as well as the duration of the ablation, the number of pulses is changed and sufficient residual corneal tissue is preserved (µm).

Avantajul invenţiei constă în aceea că metoda propusă permite prin micşorarea zonei de ablaţie şi modelarea zonei de tranziţie de a păstra mai mult ţesut cornean rezidual. Printre avantaje se mai numără securitatea, eficienţa, posibilitatea corectării miopiei şi a astigmatismului de grad înalt în caz de cornee subţire, ceea ce esenţial reduce riscul dezvoltării ectaziilor corneene postoperatorii şi extinde indicaţiile pentru efectuarea ablaţiei cu laserul cu eximeri. Grosimea stromei reziduale la utilizarea metodei propuse constituie nu mai puţin de 250...300 µm. The advantage of the invention is that the proposed method allows, by reducing the ablation area and shaping the transition area, to preserve more residual corneal tissue. Among the advantages are safety, efficiency, the possibility of correcting myopia and high-grade astigmatism in case of thin corneas, which significantly reduces the risk of developing postoperative corneal ectasias and expands the indications for performing excimer laser ablation. The thickness of the residual stroma when using the proposed method is not less than 250...300 µm.

Metoda de ablaţie asferică se asociază perfect cu cea de formare a lamboului cornean ultrafin care permite ablaţia economă a corneei, corecţia nu numai a miopiei de 10...15 D, dar şi combinaţia miopiei cu astigmatismul la pacienţi cu o grosime a corneei mai puţin de 500 µm. The aspheric ablation method is perfectly combined with the ultrathin corneal flap formation method, which allows for economical corneal ablation, the correction not only of myopia of 10...15 D, but also the combination of myopia with astigmatism in patients with a corneal thickness of less than 500 µm.

Metoda propusă de corecţie a miopiei şi a astigmatismului miopic în caz de cornee subţire a fost efectuată la 30 de ochi la 18 pacienţi. The proposed method of correcting myopia and myopic astigmatism in case of thin corneas was performed on 30 eyes in 18 patients.

Toţi pacienţii au fost supuşi unui examen oftalmologic complet. Peste 3 luni a fost efectuată OCT (tomografia optică coerentă a corneei, metoda permite de a efectua examinarea grosimii corneei în general, grosimea stromei reziduale, grosimea lamboului cornean) a segmentului anterior cu măsurarea grosimii lamboului cornean, grosimii stromei corneene reziduale. Datele sunt documentate. All patients underwent a complete ophthalmological examination. After 3 months, OCT (optical coherence tomography of the cornea, the method allows to perform examination of the overall corneal thickness, residual stroma thickness, corneal flap thickness) of the anterior segment was performed with measurement of corneal flap thickness, residual corneal stroma thickness. The data are documented.

Metoda propusă se realizează în modul următor. Se efectuează anestezia topică şi se aplică blefarostatul. Apoi se marchează corneea, după care cu un microkeratom mecanic se efectuează disecţia lamelară a lamboului cornean cu grosimea de 70...90 µm şi diametrul de 8...9,5 mm, cu picioruş nazal. Apoi lamboul cornean se dă la o parte şi se îndoaie în două. Se efectuează ablaţia asferică cu laserul cu eximeri a patului stromal cornean la instalaţia Microscan 2000. Ablaţia se efectuează în regimul spotului volant cu diametrul de 0,67 mm la o putere de 120 mlJ/cm2 şi frecvenţă de 200 Hz. The proposed method is performed as follows. Topical anesthesia is performed and blepharostat is applied. Then the cornea is marked, after which a mechanical microkeratome is used to perform lamellar dissection of the corneal flap with a thickness of 70...90 µm and a diameter of 8...9.5 mm, with a nasal pedicle. Then the corneal flap is moved aside and folded in two. Aspheric ablation of the corneal stromal bed is performed with an excimer laser on the Microscan 2000 installation. Ablation is performed in the flying spot mode with a diameter of 0.67 mm at a power of 120 mlJ/cm2 and a frequency of 200 Hz.

Există un program de calculare a ablaţiei, care face parte din pachetul de programe Microscan. Pe parcursul ablaţiei se remodelează forma asferică a suprafeţei corneene, totodată razele de lumină care trec atât prin zona centrală, cât şi prin zona perifică a suprafeţei asferice se adună într-un punct, aberaţiile sferice (dezavantajele opticii) sunt reduse mult. Metoda dată permite de a efectua ablaţia economă a corneei. După fotoablaţie, patul stromal este umezit blând cu o soluţie echilibrată, lamboul cornean se repune în poziţie iniţială. Se instilează colir cu antibiotic. There is a program for calculating the ablation, which is part of the Microscan software package. During the ablation, the aspheric shape of the corneal surface is remodeled, at the same time the light rays passing through both the central and peripheral areas of the aspheric surface are collected at one point, spherical aberrations (optical disadvantages) are significantly reduced. This method allows for economical corneal ablation. After photoablation, the stromal bed is gently moistened with a balanced solution, the corneal flap is returned to its original position. Antibiotic eye drops are instilled.

Exemplu Example

Pacienta C., 25 ani. Diagnostic: OD Miopie de grad înalt. Astigmatism miopic compus. Ambliopie de grad slab. Anizometropie. Patient C., 25 years old. Diagnosis: OD High degree myopia. Compound myopic astigmatism. Low degree amblyopia. Anisometropia.

Acuitatea vuzuală OD 0,02 cu corecţia 0,8. Tensiunea intraoculară 11,9 mm Hg (pneumotonometria). Refractometria în condiţiile cicloplegiei sph (minus sferic) -10,5 D cyl (cylindru) -2 D ax 154°. Puterea optică a corneei 45,5, raza de curbură 7,43. Pahimetria 499 µm în centru. Conjunctiva curată. Corneea netedă, transparentă. Camera anterioară de profunzime medie, umoarea apoasă a camerei anterioare transparentă. Pupila rotundă, reacţia la lumină este vioaie, asociată. Desenul irisului trabecular. Cristalinul transparent. Papila nervului optic este roz-palidă, conus miopic. Vasele retinei sunt spasmate moderat. Reflexul macular atenuat (în cazul miopiei de grad înalt retina este subţire şi reflexul nu se observă bine). A fost efectuată corecţia cu laserul cu eximeri a miopiei şi a astigmatismului miopic conform metodei propuse. La OD a fost efectuată ablaţia asferică (a fost remodelată suprafaţa asferică a corneei). Pacientei i s-a aplicat tratamentul postoperaţional standard. Au lipsit complicaţiile intra- şi postoperaţionale. Peste 3 luni după operaţie acuitatea vizuală constituia OD 0,8. Refractometria în condiţiile cicloplegiei sph -0,25 D cyl -0,5 D ax 150°. Sferoechivalentul refracţiei constituia -0,5 D. Visual acuity OD 0.02 with correction 0.8. Intraocular pressure 11.9 mm Hg (pneumotonometry). Refractometry under cycloplegia conditions sph (spherical minus) -10.5 D cyl (cylinder) -2 D ax 154°. Corneal optical power 45.5, radius of curvature 7.43. Pachymetry 499 µm in the center. Clean conjunctiva. Smooth, transparent cornea. Anterior chamber of medium depth, aqueous humor of the anterior chamber transparent. Round pupil, reaction to light is lively, associated. Trabecular iris pattern. Transparent lens. Optic nerve papilla is pale pink, myopic cone. Retinal vessels are moderately spasmed. Attenuated macular reflex (in case of high-grade myopia the retina is thin and the reflex is not well observed). Excimer laser correction of myopia and myopic astigmatism was performed according to the proposed method. Aspheric ablation was performed at OD (the aspheric surface of the cornea was remodeled). The patient underwent standard postoperative treatment. There were no intra- and postoperative complications. 3 months after the operation, visual acuity was OD 0.8. Refractometry under cycloplegic conditions sph -0.25 D cyl -0.5 D ax 150°. The spheroequivalent of refraction was -0.5 D.

1. RU 2302844 C1 2007.07.20 1. RU 2302844 C1 2007.07.20

Claims (1)

Metodă de corecţie cu laserul a miopiei de grad înalt în caz de cornee subţire, care constă în aceea că după anestezia topică şi aplicarea blefarostatului se marchează corneea, apoi cu un microkeratom mecanic se formează un lambou cornean pe picioruş de partea nazală cu grosimea de 70…90 µm şi diametrul de 8…9,5 mm, după aceasta lamboul cornean se deplasează în partea nazală, se efectuează ablaţia asferică a stromei lojei corneene cu laserul cu eximeri în regimul spotului volant cu diametrul de 0,67 mm la o putere de 120 mJ/cm2 şi frecvenţă de 200 Hz, după care lamboul cornean se repune la locul iniţial.Laser correction method of high-grade myopia in case of thin cornea, which consists in that after topical anesthesia and application of blepharostat, the cornea is marked, then with a mechanical microkeratome a corneal flap is formed on the pedicle on the nasal side with a thickness of 70…90 µm and a diameter of 8…9.5 mm, after which the corneal flap is moved to the nasal side, aspheric ablation of the stroma of the corneal lodge is performed with the excimer laser in the flying spot mode with a diameter of 0.67 mm at a power of 120 mJ/cm2 and a frequency of 200 Hz, after which the corneal flap is returned to its original place.
MDS20100189A 2010-11-12 2010-11-12 Method for laser correction of high myopia with insufficient corneal thickness MD334Z (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
MDS20100189A MD334Z (en) 2010-11-12 2010-11-12 Method for laser correction of high myopia with insufficient corneal thickness

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
MDS20100189A MD334Z (en) 2010-11-12 2010-11-12 Method for laser correction of high myopia with insufficient corneal thickness

Publications (3)

Publication Number Publication Date
MD334Y MD334Y (en) 2011-02-28
MD334Z5 MD334Z5 (en) 2011-09-30
MD334Z true MD334Z (en) 2011-09-30

Family

ID=45815031

Family Applications (1)

Application Number Title Priority Date Filing Date
MDS20100189A MD334Z (en) 2010-11-12 2010-11-12 Method for laser correction of high myopia with insufficient corneal thickness

Country Status (1)

Country Link
MD (1) MD334Z (en)

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2302844C1 (en) * 2005-12-27 2007-07-20 ЗАКРЫТОЕ АКЦИОНЕРНОЕ ОБЩЕСТВО "ОПТИМЕДСЕРВИС" (ЗАО "Оптимедсервис") Laser correction method for treating moderate or high degree myopia cases when cornea thickness is insufficient
  • 2010

Also Published As

Publication number Publication date
MD334Z5 (en) 2011-09-30
MD334Y (en) 2011-02-28

Similar Documents

Publication Publication Date Title
Shah et al. Effect of scanning patterns on the results of femtosecond laser lenticule extraction refractive surgery
Shah et al. Results of small incision lenticule extraction: all-in-one femtosecond laser refractive surgery
Esquenazi et al. Two-year follow-up of laser in situ keratomileusis for hyperopia
Shah et al. Complications of femtosecond-assisted laser in-situ keratomileusis flaps
El Danasoury et al. Excimer laser in situ keratomileusis to correct compound myopic astigmatism
Ang et al. Visual outcomes comparison of 2 femtosecond laser platforms for laser in situ keratomileusis
Stojanovic et al. 200 Hz flying-spot technology of the LaserSight LSX excimer laser in the treatment of myopic astigmatism: six and 12 month outcomes of laser in situ keratomileusis and photorefractive keratectomy
Kymionis et al. Topographically supported customized ablation for the management of decentered laser in situ keratomileusis
Fernandez et al. Early clinical experience using custom excimer laser ablations to treat irregular astigmatism
Vajpayee et al. Laser in-situ keratomileusis after penetrating keratoplasty
Lukenda et al. Excimer laser correction of hyperopia, hyperopic and mixed astigmatism: past, present, and future
Lee et al. Comparison of two procedures: photorefractive keratectomy versus laser in situ keratomileusis for low to moderate myopia
Abdulaal et al. One-step transepithelial photorefractive keratectomy with mitomycin C as an early treatment for LASIK flap buttonhole formation
Reviglio et al. Laser in situ keratomileusis for myopia and hyperopia using the Lasersight 200 laser in 300 consecutive eyes
Bilgihan et al. Microkeratome-assisted lamellar keratoplasty for keratoconus: stromal sandwich
Agarwal et al. Laser in situ keratomileusis for residual myopia after radial keratotomy and photorefractive keratectomy
Michieletto et al. PermaVision intracorneal lens for the correction of hyperopia
Spadea et al. Enhancement outcomes after photorefractive keratectomy and laser in situ keratomileusis using topographically guided excimer laser photoablation
Alió et al. Intraoperative Complications of LASIK and SMILE
Muñoz et al. Single versus double femtosecond laser pass for incomplete laser in situ keratomileusis flap in contralateral eyes: visual and optical outcomes
Messmer LASIK: a primer for family physicians
Smadja et al. Suction loss during thin-flap femto-LASIK: management and beneficial refractive effect of the epithelium
MD334Z (en) Method for laser correction of high myopia with insufficient corneal thickness
Zuberbuhler et al. Refractive Corneal Surgery
Vossmerbaeumer Application principles of excimer lasers in ophthalmology

Legal Events

Date Code Title Description
ND4Y Validity of short term patent extended [from 6 to 10 years]

Expiry date: 20201112

KA4Y Short-term patent lapsed due to non-payment of fees (with right of restoration)