Excimer laser in situ keratomileusis corneal foreign bodies in layers
Authors: Xue-Bin Hu, Fang Fang, Jiang Ping, Mo
【Abstract】 Objective: To analyze the excimer laser in situ keratomileusis (LASIK) corneal foreign bodies in the situation between layers. Methods: In LASIK surgery 6 239 cases (12 312), the emergence of postoperative residual corneal foreign body cases interlayer-related causes and treatment methods for statistical analysis. Results: 304 (2.47%) had residual
corneal foreign bodies between layers. Among them, 50 (0.41%) have foreign bodies removed and washed in a timely and reasonable measures to deal with; 254 (2.06%) do not deal with. Corrected visual acuity in all cases the expected no significant effect, when a little washed three marginal corneal epithelial cell implantation. Conclusion: LASIK surgery corneal layer foreign body left there the rate of complications is low, most cases do not deal with. Through the control of relevant factors can be effectively reduced, but
not eliminated. Timely and rational approach can improve the visual quality, LASIK surgery safe and reliable.
Key words excimer laser in situ keratomileusis; layer foreign body; corneal flap
Excimer laser in situ keratomileusis (laser in situ keratomileusis, LASIK) for its safe, effective, fast and stable characteristics, are generally accepted by the general myopia has become the mainstream of corneal refractive surgical procedure is a kinds of selective surgery icing on
the cake. However, this surgery equipment and technology, higher, higher patient expectations of surgery, if there is complications not worth the effort of the [1,2]. With the corneal flap-related complications is particularly prominent
on the corneal layer in which a simple foreign body is more coverage, but no systematic thematic analysis. Now we have since 1999/2005 to carry out LASIK treatment of myopia of 6 239 cases (12 312) generated by a variety of corneal foreign bodies between layers and their causes, treatment and prevention are summarized below.
An object and method
1.1 Object collection 1999-08/2005-08 conduct LASIK
treatment of myopia of 6 239 cases (12 312). Men and 3 101 cases (6 132), female 3 138 cases (6180 eyes). Aged 18 to 52 (mean 25.23 ? 6.68) years of age. Preoperative spherical refraction -0.75 ~-16.00DS, Cylinder diopter 0 ~-5.50DC.
Myopia and stability 2a or 2a above, stop wearing soft contact lenses for more than 2wk. Systemic contraindications to
exclude serious disease and eye disease. Preoperative drops 3g / L ofloxacin eye drops 3d.
1.2 methods include long, nearly naked eye and best corrected visual acuity, slit-lamp microscopy, direct and
indirect ophthalmoscopy dilated examination, normal, and
darkroom pupil diameter, non-contact intraocular pressure,
subjective and objective refraction, corneal topography, corneal thickness and eye axis measurement. Has adopted the U.S. Summit, Eagle, as the laser machine and the French company's pneumatic rotary Moria microkeratome Micro (M-LSK
type) surgery. Excimer laser wavelength of 193μm, corneal
flap thickness 130μm. Of the expected correction diopter, corneal thickness and pupil diameter, laser-cutting decisions
in diameter (5.00 ~ 6.50mm) and depth. Corneal diameter and corneal curvature according to the system to do 7.00 ~ 9.00mm in diameter corneal flap. Preoperative to enable patients to understand the theory and technique in surgical methods and the importance of cooperation to eliminate patient's fear.
Using conventional surgical methods and preoperative and postoperative medication. Intraoperative suction as a complete, time to try not to over 20s, were too low to attract a slightly longer time, corneal curvature, a high degree of
myopia were as short as possible; folding corneal flap
technique; flap flush with the BBS (amount of 5 ~ 20mL). 1d after eye removal, conventional medication and regular review. After the first 1,3,10 d, 1,3,6,12,24 mo referral, check the uncorrected visual acuity, corrected visual acuity, slit lamp microscopes, non-contact intraocular pressure, fundus, corneal topography and postoperative symptoms of the investigation. Some patients immediately after slit lamp microscope. Removal of corneal foreign bodies between layers: the lowest with a
variety of foreign body injury excluding law and opened all around the local wash wash corneal flap. In addition, according to the nature of the foreign body, size, degree of inflammatory response, whether in the optical zone and whether
they lead to abnormal refraction to determine the method of dealing with it or not, and flushing.
Produced in all cases of corneal foreign bodies residual layer 304 (2.47%), including the fine points, like metallic
foreign body (3 below are not statistics, two for the small rust) foreign body in 3 ~ 5 189 (1.54%), 6 ~ 9 16 eyes (0.13%), not found more than 10 foreign bodies; Kong towels, dressings, clothing or the air in the filaments; conjunctival sac Lipid secretions and oily 34 (0.28%); blood 6 (0.05%) and eyelashes and so on. Use of foreign bodies removed and washed in measures to deal with a total of 50 (0.41%), of which 11 (0.09%) 15d within a much slower visual recovery, 3mo after the vision has basically returned to the expected corrected
visual acuity, best corrected visual acuity decreased significantly without cases. 39 (0.32%) 15d after treatment to resume to the desired vision correction. After being washed in 3 eyes (0.02%), a little marginal corneal epithelial cells
implanted, no other special circumstances. Not dealt with 254 (2.06%).
Excimer laser in general a low magnification microscope with no cracks light between layers of corneal foreign bodies remaining surgery is difficult to find and completely removed. Between layers of corneal foreign bodies in this study the incidence of residual 2.47%, Ma Wah-ching in 2005 the
statistics of 1.00% , Li Li and others 2004 statistics of 2.09% , Yuan Jun and others in 2003 the statistics for the
1.00% , Liao Feng et al 2003 statistics of 0.86% , Chen Jianguo, 2002 statistics of 0.20% , Xu Wen et al 2001 statistics of 4.01% . Comparative analysis of above information, nearly every year statistical analysis of 5a shows that residual corneal foreign bodies between layers has been given due weight; due to geographical, sample size, statistics and the criterion of the foreign matter (especially the small dot judged metallic foreign bodies) different statistical results are quite different, but the incidence is low, from the time point of view, as the general LASIK and skilled to carry out a higher level of residual corneal layer between the incidence of foreign body or a downward trend. Reposted elsewhere in the paper for free download http://
3.1 corneal layer types and sources of foreign body foreign body types between layers: fine point and a small rust-like metal foreign body, filament tilting, conjunctival sac secretions of lipid classes, oil quality, such as blood
and eyelashes. Sources of foreign matter between layers: ?
fine point blade-like metallic foreign body is friction with the cutter head or cutter head and suction ring friction. Major sources of blades, for the vast majority of those who recognized surgery; followed by Segment and the suction ring, this point can be observed under the microscope and the suction ring Segment disorder scratches the surface of clouds confirmed; In addition, the very a few fine points of the same nature is derived from the cutter head and rust-like suction
ring. Instrument maintenance, from Blade and the suction ring cracks, grooves, and the lumen of a small amount of rust can be seen, operation of mechanical vibrations lead to rust loose and into the conjunctival sac, drift to the cornea under the
flap. ? tilting filaments of varying lengths, sometimes spirals; nature, mostly cotton, silk, chemical fiber type followed by a handful of properties is not clear; the main sources of hole towel, surgical clothing, dressings, blood-
sucking sponges, clothing or between doctors and patients objects floating in the air. In this study, 1 case of corneal flap blue-violet fiber type filament, remove the operating room with us after a medical staff of the sweater fibers under the microscope proved to be the same substance more. ? Lipid
conjunctival sac secretions from the meibomian glands and Zeis glands. There exists an obvious individual differences, strong secretion common in young people. ? oil can be seen
occasionally and may be micro-microkeratome motor clean
lubricant left in the motor, the operation starts repeatedly motor oil spill from the cutter head into the corneal flap harvesting. ? limbal capillary blood from wing injury,
bleeding does not thoroughly penetrate the blood under the
corneal flap; Segment and the negative pressure due to the mutual pull ring injury in the few cases where conjunctival blood vessels, bleeding is generally not retained to the corneal flap. ? eyelashes were retained under the corneal flap [1,2], our hospital does not occur, generally due to the cutter head and suction ring pull each other the eyelashes to fall off the formation of those who occasionally fall off on their own.
3.2 The treatment of corneal foreign bodies between layers principle and method of management principles: In
accordance with asymptomatic, the nature and size of the foreign body, inflammatory reaction, signs of infection, whether in the optical zone and whether they lead to abnormal refractive status and visual recovery and other factors
decision. The particularity of the cornea after LASIK cautioned us in dealing with corneal foreign bodies between layers, we must give further consideration to evaluate, not handled properly, runs the risk of causing even more adverse consequences. Foreign bodies in the various layers approach: ? difficult to remove metal debris , the nature of stability in the corneal layer is generally no need to deal with; when larger metal debris, located optical zone, resulting in abnormal refractive status or visual
significantly affected when the corneal flap can be opened and flipped a large number of BBS wash, rinse, when observe corneal edema conditions and do too little. If necessary, can be used in conjunction with 1mL syringe needle with the needle
carefully removed, and where possible reduce the corneal flap and stromal bed damage; of these, small rust pitting the two
in order to prevent the formation, are carefully scrape and fully flush. ? filament tilting easy to remove, unless the short and small, non-distorted nature of the stable and mild inflammatory reaction and are located in non-optical area, we
generally have taken reasonable measures to deal with. Corneal flap margin of those who nearly carried out around the partially opened washing, BBS use is normally less than 1.5mL; 2 Yan thin filament in the peripheral corneal flap, the end of the exposure, using micro-tweezers directly pulled out, no
corneal flap lifted ; the rest of them opened a whole corneal
flap, flap, or flip to stack big flush valve open , generally do not need to remove the foreign body. ? Lipid
conjunctival sac secretions, fat and blood. Lipid secretions
generally do not deal with the vast majority can be self-
absorbed . Processing of the eight cases in three categories for the lipid secretions, grease 2 and blood 3. Can be a general wash. ? We layer foreign body, after washing, 3 eyes (0.02%) occurred without handling a few marginal corneal epithelial cell implantation. However, epithelial implantation serious, may cause foreign body sensation, decreased vision, glare, astigmatism and corneal stroma or corneal flap melting [11,12]. Therefore, the flushing should be noted that any possible solution to the cornea, or corneal flap edema Pison reasons: If too many drops to use anesthesia for preparation, intraoperative corneal flap is too dry, intraoperative corneal scratch the surface of surgical instruments, surgery several
times between the middle washing and so on, to prevent corneal epithelial cells under the flap implantation .
3.3 Prevention of corneal foreign bodies between layers must be based on the source layer foreign body to take
specific measures to be targeted to obtain a good preventive effect. First of all, require thought to have sufficient knowledge and attention. Second, the beginner should pay extra careful attention to every surgical procedure, known instrument performance, improve surgical techniques, while seeking the active support of patients is to avoid these complications and to achieve surgical success. Again, detailed and comprehensive grasp aspects: ? the operating room space
allocation, decoration materials, air-conditioned air flow
direction of the wind, patients and medical staff clothing, personal hygiene and staff mobility and other factors related to air purification; ? preoperative corneal detailed
examination and assessment; ? conjunctival sac of
preoperative full cleaning and eyelashes; ? using high-
quality consumables, Cutter and vacuum ring cleaning and maintenance, and check the knife before Shica Cutter with the blade, the operating table vacuum ring Segment and washing the direction of the placement of needles and other equipment; ?
limbal vascular injury and bleeding control; ? corneal flap
and stromal bed smoothness and corneal flap thickness and flexibility of the control estimates; corneal flap pedicle location; stacked valve technology adoption or not; flush out
the needle and the direction of flow of water and washing
between layers of the validity of the factors easily lead to foreign body retention. Finally, we believe that the production of corneal foreign bodies between layers are mostly
controllable factors can be significantly reduced through prevention, but the complexity of the relevant factors, not eliminated. Even if the occurrence of a reasonable and timely treatment can prevent or mitigate damage to visual function, still get a better visual quality .
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