Study On The Changes Of Ocular Surface And Tear Film After Laser Surgery And Comparison Of Therapeutic Reaction From Different Artificial Tears

BackgroundExcimer laser surgery is a widely used myopia correction method at present. During20years of development, advanced inspection equipments, sophisticated microkeratomes, increasingly accurate and efficient excimer laser instruments, deeply understanding of the surgery and skillful technology make the accurate prediction of postoperative refraction, excellent visual acuity and visual quality, safety operation and corneal biomechanics keeping in a safe range after operation become possible. But there is still a problem not to be avoided, that is the changes of ocular surface and tear film brought from the operation can cause or aggravate the preoperative dry eye. Dry eye is a class of diseases of the eye discomfort due to the quantitative or qualitative abnormalities of tear caused by instability of tear film and ocular surface damage. Dry eye affects the wound healing and the optical quality, increases the risk of refractive regression, causes discomfort after operation and reduces the satisfaction of the surgery. Therefore, the research and prevention of dry eye should be attached importance. When we design operation, we should consider not only the safety of operation, operability, visual quality and patients’ special requirements, but also the excimer laser-associated dry eye. Excimer laser-associated dry eye is temporary and mild to moderate dry eye. The most direct treatment of postoperative dry eye is using artificial tears. Because there is no exact conclusion that which one is the best among all kinds of artificial tears, the prescription of the artificial tears still depends on doctors’habits. The treatment will be very meaningful while chosing artificial tears according to the different situation of dry eye after operation. This study will be divided into three parts to investigate the change of the corneal surface morphology and tear film after the four surgeries in mainstream at present, analyse the dry eye condition after different surgeries and discuss the therapeutic reaction characteristics of different artificial tears. So that we choose the appropriate surgery in consideration of dry eye and select the suitable artificial tears according to different conditions of dry eye.Part1. Change of ocular surface and tear film after different methods of operationObjective:1. To investigate the changes of subjective symptoms, tear break-up time, corneal fluorescein staining and basal tear secretion after the four kinds of excimer laser refractive surgery, SBK, LASIK90, LASIK110and PRK in myopia.2. To investigate the difference of symptoms, tear break-up time, corneal fluorescein staining and basal tear secretion after refractive surgeries with superior-temporal hinge of corneal flaps and superior-nasal hinge of corneal flaps.Methods:1.84patients (male50cases, female34cases) with myopia or myopic astigmatism were enrolled in this study who accepted voluntarily refractive surgery to our optometry and ophthalmology center. The age range was18～38years, average (25.46±5.44) years. The spherical equivalent was-1.125～9.375D, average (-4.80±2.06) D. They were divided into four groups:SBK group, LASIK90group, LASIK110group and PRK group and21right eyes were in each group. There was no statistical significance for age among groups. There were statistical significance for spherical equivalent and cutting depth among groups. All the subjects were accepted the standard surgery by the same doctor. Symptoms, tear break-up time (BUT), corneal fluorescein staining (CFS) and basal tear secretion (S I T) were measured before and1week,1month and3months after surgery.2.42cases (84eyes) who were accepted LASIK90and LASIK110were divided into two groups: superior-temporal hinge group (42right eyes) and superior-nasal hinge group (42left eyes). The spherical equivalent and cutting amount of superior-temporal hinge group was greater than superior-nasal hinge group and the difference was statistically significant. Symptoms, tear break-up time, corneal fluorescein staining and basal tear secretion were measured before and1week,1month and3months after surgery.Result:1. About the four groups:1.1The changes of symptoms:From before to3months after surgery as a whole, the difference of symptom scores between groups was not statistically significant (F=0.405, P=0.750). The difference of the score between time points was statistically significant (F=16.239, P<0.001). There was no interaction effect of group and time (F=1.504, P=0.167). The variation tendency with time of the symptom score was the same by the four groups. The score had no significant differences at each time point after surgery compared with pre-operation in SBK group. The scores of lm or3m after surgery were both lower compared with pre-operation in LASIK90group and the difference was statistically significant. The scores of3m after surgery was lower compared with pre-operation in LASIK110group and the difference was statistically significant. The scores of1w after surgery was lower compared with pre-operation in PRK group and the difference was statistically significant. The most obvious symptoms before surgery were blurred vision and asthenopia. The mildest symptoms before surgery were foreign body sensation and ophthalmodynia. After operation, the most obvious symptoms were foreign body sensation, photophobia and ophthalmodynia. The mildest symptoms were blurred vision, asthenopia and tears running.1.2The changes of stability of tear film:From before to3months after surgery as a whole, the difference of BUT between groups was not statistically significant (F=0.654, P=0.583). The difference of BUT between time points was not statistically significant (F=0.029, P=0.993). There was no interaction effect of group and time (F=0.996, P=0.444). The variation tendency with time of the BUT was different by the four groups. The trends of SBK group and PRK group were closed and the trends of LASIK90group and LASIK110group were closed. The BUT of lw after surgery was lower compared with pre-operation in LASIK110group and the difference was statistically significant. Regardless of preoperative or postoperative, the lower part of cornea was the most frequent site of tear film break-up and the upper cornea was the rare site.1.3The changes of CFS:From before to3months after surgery as a whole, the difference of CFS score between groups was not statistically significant (F=0.828, P=0.483). The difference of CFS score between time points was statistically significant (F=20.292, P<0.001). There was interaction effect of group and time (F=3.946, P<0.001). The variation tendency with time of the CFS score was the same by the four groups. The scores of lw after surgery was higher compared with pre-operation in SBK group and the difference was statistically significant. The scores of lw or lm after surgery were both higher compared with pre-operation in LASIK90group and the difference was statistically significant. The score had no significant differences at each time point after surgery compared with pre-operation in LASIK110group. The scores of lw after surgery was higher compared with pre-operation in PRK group and the difference was statistically significant.1.4The changes of S I T:From before to3months after surgery as a whole, the difference of S I T between groups was not statistically significant (F=0.234, P=0.873). The difference of S I T between time points was not statistically significant (F=2.118, P=0.099). There was no interaction effect of group and time (F=0.357, P=0.954). The S I T of lw after surgery was lower compared with pre-operation in LASIK110group and the difference was statistically significant. The variation tendency with time of the S I T score was the same by the these groups but PRK group. PRK group had no obvious change.2. About the two different hinge location groups:2.1The changes of stability of tear film:From before to3months after surgery as a whole, the difference of BUT between groups was not statistically significant (t=0.071, P=0.790). The difference of BUT between time points was statistically significant (t=3.722, P=0.012). There was no interaction effect of group and time (t=0.645, P=0.587).2.2The changes of CFS:From before to3months after surgery as a whole, the difference of CFS between groups was not statistically significant (t=0.079, P=0.779). The difference of CFS between time points was statistically significant (t=10.596, P<0.001). There was no interaction effect of group and time (t=0.629, P=0.578).2.3The changes of S I T:From before to3months after surgery as a whole, the difference of S I T between groups was not statistically significant (t=1.412, P=0.239). The difference of the score between time points was not statistically significant (t=5.073, P=0.002). There was no interaction effect of group and time (t=0.028, P=0.994).Conclusion:These four kinds of operation’s characteristics were as follows. The SBK group had the greatest impact on symptoms later after surgery. The LASIK90group had the minimum impact on symptoms after surgery. The LASIK110group had the minimum impact on corneal epithelium, but the greatest impact on BUT and S I T early after surgery. The PRK group had minimum impact on S I T, but the greatest impact on symptoms early after surgery. Part2. The morphological changes of corneal anterior surfaceObjective:To investigate the changes of irregular surface index (CIM), shape index (SF), the steep curvature and smooth curvature (K1and K2) after surgery. Study on SBK, LASIK90, corneal LASIK110and PRK group were changes and at the same time analyse the relationship between these parameters and related factors.Method:75eyes with simple myopia who need spherical cutting were enrolled in this study who accepted voluntarily refractive surgery to our optometry and ophthalmology center. The average cutting depth was (84.31±14.83) μm in SBK group (18eyes),(69.91±23.81) μm in LASIK90group (12eyes),(69.13±20.14) μm in LASIK110group (23eyes) and (55.26±15.79) μm in PRK group (22eyes). There was statistical significance for cutting depth among groups. All the subjects were accepted the standard surgery by the same doctor. Corneal topography was measured before and1week,1month and3months after surgery.Result:1. The trends of CIM, SF, K1and K2over time:The CIM was increased on1w after surgery, decreased on lm except SBK group and remained unchanged on3m except PRK group. The SF, K1and K2all decreased on lw after surgery and remained unchanged on lm and3m.2. Correlation of the anterior corneal surface morphological parameters:There is a significant positive correlation between△SF andA K or△K2, as well as△K1and△K2each group.△SF,△Kl and△K2was negatively correlated with cutting depth, cutting/corneal thickness and cutting/bed thickness. There was no significant correlation between intraocular pressure and△CIM,△SF,△K1or△K2. The regression linear variable coefficient was the maximum between cutting/corneal thickness and these parameters. The△CIM regression linear coefficient with cutting/corneal thickness was in turn into LASIK110group, SBK group, LASIK90group, PRK group from large to small. For△SF was SBK group. LASIK110group. PRK group. LASIK90group. For AK1was LASIK110group. PRK group. SBK group. LASIK90group.3. The change of CIM:From before to3months after surgery as a whole, the difference of CIM between groups was not statistically significant (F=2.122, P=0.107). The difference of CIM between time points was statistically significant (F=39.118, P<0.001). There was interaction effect of group and time (F=5.119, P <0.001). The variation tendency with time of the CIM was the same by the three groups except SBK group.Conclusion:1. It was LASIK110group that the irregularity of corneal anterior had linear regression with cutting.2. It was SBK group that caused the most obvious morphological changes of corneal anterior surface and the lightest was LASIK90group.3. It was LASIK110group that caused the most obvious Changes of corneal anterior surface curvature and the lightest was LASIK90group. Part3. The therapeutic reaction of surgery-associated dry eye by sodium hyaluronateObjective:To investigate the therapeutic reaction of ocular surface and tear film after surgery by different sodium hyaluronate (SH) eye drops.Methods:84patients (male50cases, female34cases) with myopia or myopic astigmatism were enrolled in this study who accepted voluntarily refractive surgery to our optometry and ophthalmology center. The age range was18～38years, average (25.46±5.44) years. The spherical equivalent was-1.125～9.375D, average (-4.80±2.06) D. They were divided into three groups:group A (0.1%SH with BAC), group B (0.1%SH without BAC), group C (0.3%SH without BAC) and28right eyes were in each group. There was no statistical significance for age, spherical equivalent and cutting depth among groups. All the subjects were accepted the standard surgery by the same doctor. Symptoms, tear break-up time (BUT), corneal fluorescein staining (CFS) and basal tear secretion (S I T) were measured before and lweek,1month and3months after surgery.Result:1. The therapeutic reaction of symptoms by SH:From before to3months after surgery as a whole, the difference of symptom scores between groups was not statistically significant (F=0.920, P=0.403). The difference of the score between time points was statistically significant (F=15.591, P<0.001). There was no interaction effect of group and time (F=0.934, P=0.458). The variation tendency with time of the symptom score was the same by the three groups. At each time ophthalmodynia of group B was slighter than group A and C. Photophoby of group B and C was slighter than group A.2. The therapeutic reaction of tear film stability by SH:From before to3months after surgery as a whole, the difference of BUT between groups was not statistically significant (F=0.264, P=0.769). The difference of BUT between time points was not statistically significant (F=0.029, P=0.993). There was no interaction effect of group and time (F=1.204, P=0.305). The variation tendency with time of BUT was opposite by group A and B. Group C had little fluctuation at each time.3. The therapeutic reaction of CFS by SH:From before to3months after surgery as a whole, the difference of CFS between groups was not statistically significant (F=0.052, P=0.950). The difference of CFS between time points was statistically significant (F=18.409, P<0.001). There was no interaction effect of group and time (F=0.866, P=0.521). The variation tendency with time of CFS was the same by the three groups.4. The therapeutic reaction of S I T by SH:From before to3months after surgery as a whole, the difference of S I T between groups was not statistically significant (F=0.028, P=0.973). The difference of S I T between time points was not statistically significant (F=2.522, P=0.059). There was interaction effect of group and time (F=2.325, P=0.034). The variation tendency with time of S I T was the same by group A and C, but opposite with group B.Conclusion:1. The0.1%SH or0.3%SH without BAC eye drops was the better choice for obvious symptoms after surgery esp. photophoby and who need use artificial tears for long time more than1month. It was suitable for obvious ophthalmoldynia patients to choose0.1%SH without BAC eye drops.2. The0.3%SH without BAC eye drops was the better choice for the tear film instability caused by eyesight fluctuation.3.0.1%SH was suitable for severe CFS after surgery.4. The0.1%SH or0.3%SH without BAC eye drops was suitable for the patients with little basal tear secretion before surgery and0.1%SH without BAC was better.