摘要：目的评价准分子激光角膜切削术矫正近视的结果。方法我院自1996年9月到1997年10月，应用SVS APEX型(Summit Technology Inc.USA)准分子激光治疗仪，对168例近视患者(316只眼)行PRK手术，对其中的150例(260只眼，占84%)患者随诊至少3mo以上，最长1a；男68例(116只眼，占40.1%)，女82例(144只眼，占59.9%)。150例(260只眼)近视患者术前等值球镜屈光度为-1.25～-10.00D(-4.67D±1.63D)，散光0～-2.00D(-0.33D±0.45D)；按屈光度分为两组：A组(-1.25～-5.90D)，B组(-6.00～-10.00D)。结果A组术后第10天，有68.9%(132/220)裸眼视力达到矫正视力，1、3、6和12mo分别为90%、96%、95%和94%.B组术后第10天，有35.9%(13/40)裸眼视力达到矫正视力，1、3、6和12mo分别为83%、87%、86%和84%.全组仅3只眼(0.64%)除外，均为0.5～1.0级的角膜上皮下雾状混浊，其出现的百分比手术后10d和1、3、6、12mo分别为32.9%、84.2%、62.4%、9.0%和2.8%.结论提示准分子激光角膜切削术治疗-10.00D以内的近视是一种安全有效、稳定性好、预测性强的方法，-6.00D以下效果更好。

分类号：R776.62;R778.1⁺1文献标识码：A

文章编号：1003-5141(2000)01-0005-05

Evaluation of excimer laser photorefractive keratectomy for treatment of myopia and myopic astigmatism

ZHANG Hua

(Assiduously studying for his Doctor degree in Xi'an Medical University)

GUO Rong-Xia,SUN Nai-Xue,WANG Feng,ZHANG Dao-Guo,WANG Tong,SUN Jian,YANG Zhen-Guo,HU Hai-Tao,REN Hui-Min,LIU Yong

(Department of Ophthalmology,the First People's Hospital of Jining,Jining 272111,Shandong Province,China)

Abstract：ObjectiveTo evaluate the efficacy and accuracy of photorefractive keratectomy(PRK) for myopia and myopic astigmatism.MethodsSVS APEX PLUS excimer laser with a wave length of 193nm(Summit Technology Inc.Waltham,Mass,USA) was applied.Three hundred and sixteen myopic eyes of 168 patients were treated with PRK from Suptember 1996 to October 1997,and 260 eyes(84%) of 150 patients were followed-up for more than three month,including male 68(116 eyes,40.1%) and female 82(144 eyes,59.9%).The preoperative spherical equivalent refractive errors ranged from -1.25D to -10.00D(mean -4.67D± 1.63D),and astigmatism ranged from 0 to -2.00D(mean -0.33D±0.45D). The patients were divided into two groups according to the refraction:group A(from -1.25D to -5.90D) and group B(from -6.00D to -10.00D).The number of eyes in the two groups were 220 and 40,respectively.ResultsIn group A,After 10 days,68.9% had the uncorrected visual acuity(UCVA) equal to or one line better or lower than the preoperative best corrected visual acuity(BCVA).After 1 ,3,6 and 12 months,90%,96%,95% and 94% had the UCVA equal to or one line better or lower than the preoperative BCVA,respectively.In group B,after 10 days,1,3,6 and 12 months,UCVA equal to or one line better or lower than the preoperative BCVA occurred in 35.9%,83.0%,87.0%,86.0% and 84.0% of the patients respectively. Most of the haze showed 0.5～1 grades except 3 eyes with the haze of 2 grade at 3 or 6 months and it changed to l and 0.5 grade respectively at one year.after 10 days and 1,3,6,12 months postoperatively,the corneal haze was noted in 32.9%,84.8%,62.8%,9.0%and 2.8% of the treated eyes respectively.ConclusionWe found that the 193nm excimer laser PRK is a predictable,safe,stable,and effective refractive surgery for correcting myopia up to-10.00D in Chinese patients,and the effect is better in myopia lower than -6.00D.

Key words：excimer laser photorefractive keratectomy;myopia;myopic astigmatism▲

In 1983,Trokel,et al^［1］ first reported the laboratory reasearch about excimer laser.Clinical using of excimer laser photorefractive keratectomy were begun by Marshall,et al^［2］in 1988. During the last dacade,a new corneal refractive surgery-excimer laser photorefractive keratectomy(PRK) has been developed rapidly^［3-8］.

The excimer laser produces high-energy UV radiation pulses with a 193nm wave length.The energy absorbed by the cornea with each pulse is sufficient to cause disruption of intramolecular bonds and ablation of corneal tissue with submicron accuracy and minimal effect on adjacent tissue^［3］.The argon fluoride exeimer laser has emerged asa powerful tool in the surgical treatment of myopia.PRK is a new refractive surgery that is gradually accepted by both surgeons and patients worldwide.This studypresents the results of 260 visible eyes treated with PRK and followed up for more than three month to evaluate the predictability,stability and safety of PRK.

PATIENTS AND METHODS

Selection of patientsTo be eligible for inclusion in this study,patients were required to be at least 18 years of age,have stable myopia of up to -10D at the corneal plane with or without stable astigmatism of up to -2D,and have best corrected visual acuity of 0.8 or better.

Preoperatively,all the patients were asked to explain their refractive and spectacle histories.Wearers of soft contact lenses were assessed 2 weeks after lens removal.All the patients received a routine ophthalmic examination including dominant eyes,slit-lamp microscope and ophthalmoscopic examinations,intraocular pressure(IOP)measured by non contact tonometer(NCT),uncorrected visual acuity(UCVA)and the best corrected visual acuity(BCVA),corneal topography(corneal analysis system,EYESYS,USA)and skiascopy to detect spherical errors or spherical equivalent errors in patients with astigmatism.Then the plans were made to correcting spherical or spherical equivalent errors.Patients were excluded if they had a history of ocular trauma or surgery,keratoconus,ocular or significant systemic diseases,or if they were receiving therapy likely to interfere with corneal wound healing.For example,patients with dry eye syndrome,keratoconjunctivitis,uveitis,keratoconus,keratoglobus,glaucoma,autoimmune and diabetic disease,and these incapable of cooperating during the operation being excluded. Written informed consent was provided by each patient.

PatientsFrom September,1990 to October,1997,we treated 316 myopic eyes of 168 patients and 260 eyes(84%) of 150 patients were followed-up for more than three months,including male 62 cases(116 eyes,40.1%) and female 82 cases(144 eyes,59.9%).The preoperative spherical equivalent refractive errors ranged from -1.25D to -10.00D(mean -4.67D± 1.63D),and astigmatism ranged from 0 to -2.00D(mean -0.33D±0.45D).The patients' ages ranged from 18 to 50 yearsold (average 27 years old).We divided the patients into 2 groups according to refraction:groups A(from-1.25D to -5.90D) and group B(from -6.00D to -10.00D).The number of eyes in the two group were 220 and 40 respectively.

Surgical techniquesSVS APEX PLUS excimer laser with a wave length of 193nm(Summit Technology Inc.Waltham,Mass,USA) was applied.The pulse energy density was set at 180mJ／cm²,pulse frequency at 10Hz,maxmium ablation diameter 6.0mm,and ablation depth 0.25μm per pulse.From -1.25D to - 6.0D,the patients received a single-step procedure.From -6.00D to - 10.00D,the patients received a multi-zone procedure.5 minutes before operation,5g·L^-1 dicaine were instilled to constrict pupil for determining optical center during ablation and act as topical anesthesia respectively.The patient was trained 1-2 times to fixate monocularly at the indicatory light well during the operation.Aiming He-Ne beams were focused by 3-dimensional space localization to insure that the ablation was at the optical center of cornea.A paton was used to remove the epithel