Double-sided Cutting excimer laser in situ keratomileusis and refractive regression analysis Haze
Author: Yuan Man-Hong Deng Zhen Li Wei Li Xiao
Zhen Zhou Hua States
【Abstract】 Objective: To evaluate excimer laser in situ
double-sided Cutting keratomileusis (both-sided LASIK, BSL)
the safety and effectiveness. Methods :2004-12 / 2005-10 in
our hospital to conduct BSL surgical treatment of 38 cases of patients with high myopia 75, a retrospective analysis of clinical efficacy. Results: The follow-up 9 ~ 15mo, 38
patients with no serious complications. Before surgery, 1d, and 9mo the average uncorrected visual acuity were 0.07 ?
0.05,0.67 ? 0.29,0.92 ? 0.23, pairwise comparison between
the difference was significant (P <0.01). 1mo pm See 7 (9%)
had a Haze formation of slightly more than conventional LASIK. Computer optometry 1d and 1mo and 3mo and 6mo comparison between the differences were statistically significant, 1mo, and 3mo and 6mo, and 9mo no statistically significant
difference between the. Conclusion: BSL able to obtain a better postoperative uncorrected visual acuity and no serious complications, refractive regression to a lesser extent, Haze formation of slightly more than conventional LASIK for high myopic patients with thin cornea is a more ideal, safe and effective treatment.
Key words high myopia LASIK corneal haze refractive regression
Analysis of corneal haze and regression of both-sided
laser in situ keratomileusis
Abstract AIM: To assess the safety and effectiveness of
both-sided LASIK (BSL). METHODS: Seventy-five eyes with high
myopia were treated with BSL, and the clinical results were analyzed. * RESULTS: All of 38 cases were successful without severe complication and followed up 9 months to 15 months.
Preoperatively, the average uncorrected visual acuity (UCVA) was (0.07 ? 0.05), 1 day and 9 months after operation, the average UCVA was (0.67 ? 0.29), (0.92 ? 0.23) ,
respectively. There were obvious difference (P <0.01) among preoperative UCVA, postoperative UCVA at 1 day and 9 month, respectively. Seven eyes (9%) showed denser haze (grade 1) at 1 month. More corneal haze was observed in BSL than in routine LASIK. There were obvious difference among compute refraction at 1 day and 1 month as well as at 3 months and 6 months. CONCLUSION: BSL is a safe and effective refractive surgery for treating high myopia with thinner cornea, and it can obtain better UCVA without postoperatively severe complications and significant regression.
* KEYWORDS: high myopia; excimer laser surgery; haze; regression
Excimer laser in situ keratomileusis (LASIK) for myopia, myopia in recent years has become more desirable as a surgical method [1]. In the treatment of high myopia has a incomparable
superiority of the [2,3], but the high myopia and corneal thickness in patients with a relatively thin, which may not guarantee adequate postoperative residual corneal bed thickness, so the operation is limited. Double-sided Cutting
excimer laser in situ keratomileusis (both-sided LASIK, BSL)
for such patients with a possible solution, I use BSL hospital 2004-12/2005-10 treatment of corneal thickness is relatively thin 38 cases of patients with high myopia, as follows.
An object and method
1.1 Object 2004-12/2005-10 hospital for BSL I treated 38
cases of 75 patients, 6 were male 11, female 32 cases of 64, aged 18 to 45 (mean 26 ? 7.1) years of age. Spherical degree -6.0 ~ -14.0 (mean -8.5 ? 2.5) D, Cylinder degrees 0 ~ -4.0
(mean -1.1 ? 0.9) D, spherical equivalent -6.1 ~ -14.8
degrees (an average of -9.1 ? 2.6) D. All patients were
excluded surgical contraindication. Preoperative examination included uncorrected visual acuity, corrected visual acuity, near vision, far vision, slit lamp, non-contact tonometer,
fundus, ultrasonic corneal thickness, dilated retinoscopy,
Orbscan-? topography and so on.
1.2 Methods of Germany, as produced by Shu Rong-ming, the
fifth-generation excimer laser therapeutic apparatus and French-made Moria - ? automatic rotary type micro-lamellar
knife. Combination of preoperative central corneal thickness
and total depth of cut taken together, flip flap both in the corneal flap and stromal bed substrate surface excimer laser cutting to do in order to ensure the remaining corneal stromal bed thickness of at least the principle of not less than 250μ
m to determine the corneal flap substrate surface cutting the number of refraction. Corneal flap thickness of 110μm
selected in the corneal stromal bed using 6.5mm cutting area, corneal flap substrate surface using 4.5mm cutting area. 5min preoperative drops used 4g / L times the promise hi eye drops three times the surface anesthesia, routine disinfection, shop towels, open eyelid device to open eyelid. Marker in the cornea with gentian violet leather line optical center position mark, set in the central corneal suction ring, check
the intraocular pressure over 65mmHg, the bottles and mini-
automatic rotating lamellar knife, do the pedicle at 12:00 vertical corneal flap, about 30 radians, 110μm thickness. Dry
with absorbent sponge conjunctival sac and corneal surface
water, turning smooth leather flap attached to the stent at the corneal flap, the abolition of eye tracking, center-marked
for scanning center, double-cross-fractured horizontal band of
light to determine corneal flap for corneal flap substrate
surface a first step, laser-cutting. Target centers to the
pupil optical center, restore eye tracking, the second step of the matrix-bed laser cutting, cutting is completed under the flap with BSS wash, reset corneal flap, no rupture, lines, shifting. Operation with the Code must be completed
immediately drops Shu, Aili eye drops, using a rigid transparent cover eye care. 1d after removal of a transparent goggles, point code must Shu, Aili eye drops. Code must Shu eye drops after 1wk, 4 times / d, after reviewing the
situation according to reduce it. Aili eye drops 6 ~ 8 times / d. After regular review to check the contents of the same preoperative.
Statistical analysis: application of international common SPSS12.0 statistical software to calculate the parameters mean
? standard deviation, statistical percentage of cases, and do
t test.
2 Results
2.1 In general no one cases of intraoperative flap break formation in some patients after a slight foreign body sensation, stimulating a sense of slightly heavier than
conventional LASIK surgery, 1wk to basically disappeared, no one cases of postoperative corneal flap folds or
displacement , 1mo Tokimi 7 (9%) had a Haze formation, compared with the same period in our hospital conventional
LASIK (3.1%) slightly, adjusting the dosage of hormones after, 3mo time except for 1 patient is still a Haze, the remaining 6 There were no patients with Haze and other complications, 9mo gradually reduce when the patient Haze (0.5), but did not completely disappear. BSL appears Haze in 7 cases, except 1 case of preoperative spherical equivalent of-7.0D degrees, the
rest are in-10.0D or more, and the total cutting depth of 80 ~ 100μm there are two cases,> 100μm in 5 cases . Corneal flap
substrate surface depth of cut are> 24μm (Table 1). In
accordance with the principles of random selection and matching with the same period of time equal to the BSL degree in patients with LASIK compared between patients with (if not the same degree, may choose to close with a low degree), LASIK
patient's circumstances such as in Table 2 . OK LASIK surgery patients and line BSL surgery compared to the former depth of cut can be seen that although the deep, but after 1d of visual acuity and visual recovery within 3mo are good, basically
reached the preoperative best corrected visual acuity, but also Haze appears only 3 cases (7 cases among the selected), and completely disappear when the medication after 6mo.
2.2 The uncorrected visual acuity and spherical equivalent degree in the group of patients before surgery, 1d, and 9mo the average uncorrected visual acuity were 0.07 ?
0.05,0.67 ? 0.29,0.92 ? 0.23, 22 showed significant
difference between the (P values were 0.000,0.000,0.014, are "0.05. Table 3). Sequential stages of computer optometry
compare the results obtained: 1d, and 1mo and 3mo and 6mo comparison between the difference was significant (t values were 8.04,2.26, P all "0.05), while 1mo and 3mo and 6mo and 9mo no statistically significant difference between the (t
values were 0.63,1.10, P are "0.05), and with time, from the early operative overcorrection gradually turned to surgery
later undercorrection, but less Jiao range are in-1.00D or
less (Table 3).
3 Discussion
LASIK for correction of high myopia (-9.0D or less) the
effect is no doubt, has been achieved in clinical treatment is satisfactory [1], is the modern ideal of refractive corneal surgery. But for ultra-high myopia (-10.0D above) correction,
corneal thickness due to the restrictions, many have a strong
desire Zhai lens surgery patients to do as intended. In this study a relatively thin corneas and high myopia patients with BSL surgery, results showed that although the postoperative reaction slightly heavier than traditional LASIK surgery, vision recovery slower, Haze formation slightly. However, postoperative uncorrected visual acuity and computer optometry statistics, we can see that the surgery is obviously effective, but after reaction with reduced uncorrected visual acuity was an overall upward trend in the observation period of refractive regression the situation is not serious. Haze and refractive regression of the disease and wish to correct refractive cutting depth and time and the beam energy was positively correlated with individual differences in wound
healing, cutting patterns, irregular basement membrane and other relevant [4]; in this group occurred mainly Haze cutting too deeply in the total cases, indicating the number of preoperative refraction higher the deeper the cutting depth of
intraoperative and postoperative response to the more weight, the greater the chance there Haze, Zhou Rui-Qin et al [5] that
the corneal stroma layer depth of cut are likely to affect Haze after PRK is an important factor in place. Hence, the control operation in the cutting depth is the key to prevent the Haze place. Reposted elsewhere in the paper for free download http://
Corneal epithelial basement membrane and Bowman layer destruction is the formation of the start of factors Haze [6-
8]. Haze formation of this group of cases more than the LASIK surgery, and mainly in the corneal flap cutting deeper stromal surface cases, the same time period a similar degree between the BSL and the comparison shows that LASIK patients: LASIK although the depth of cut deeper, but the Haze has, however small, indicating the emergence of BSL after Haze may be mainly in the corneal flap or with the substrate surface to
cutting damage of the corneal epithelial basement membrane and Bowman layer. To ensure that BSL surgery without injury
corneal epithelial basement membrane and Bowman layer, reduce the occurrence of Haze, corneal flap substrate surface can be cut in theory, should not exceed the depth of corneal flap thickness and corneal epithelial thickness and elastic
thickness of the difference between the former. On the corneal epithelium and Bowman layer thickness is currently no coherent argument, some people think that corneal epithelium thickness 35μm, before the elastic thickness of about 12μm [9], it was
pointed out that the corneal epithelium thickness 50μm,
before the elastic thickness of about 8 ~ 14μm [10], also
expressed that the cortical thickness of the cornea 50 ~ 100μ
m, the former elastic thickness of about 8 ~ 14μm [11]. If
the above-mentioned three kinds of concepts as the corneal
epithelium with a mean elastic layer thickness, this group of cases of corneal flap substrate surface depth of cut can not exceed 45μm. However, this group of cases of corneal stromal flap surface ablation depth of more than 24μm have already
appeared in patients with Haze, but also all the 75 affected eyes of the corneal stroma surface cutting depth of 7 to 37 (mean 22.8 ? 4.5) μm, of which 31 cases (41 %) over 24 (24 ~ 37, with an average 26.2 ? 3.6) μm, but only 7 patients had
Haze, so this may also be the actual corneal flap thickness and auto-rotating lamellar corneal flap thickness in the default knife there are differences about. In this group showed that the corneal flap for the 110μm corneal flap
substrate surface depth of cut is best not to over 24μm, but
the specific values still need to sum up a long-term clinical
observation.
Prevention and treatment of glucocorticoid Haze and refractive regression, one of the drugs [12,13], postoperative patients in this group must be chosen for the code that
contains a long-acting type Shu glucocorticoid - dexamethasone
eye drops eye drops, to reduce the postoperative reaction, significantly reducing the efficacy of Haze. However, patients should be emphasized on a regular basis after referral, in a
timely manner under the slit lamp inspection at any time to adjust medication, as far as possible to eliminate Haze, and should observe the intraocular pressure of the situation in order to prevent the occurrence of steroid-induced high
intraocular pressure.
In short, BSL treatment of corneal thickness is relatively thin and high myopia able to obtain a better postoperative visual acuity, no serious complications, refractive regression still exists, but to a lesser extent,
Haze occurs slightly heavier than conventional LASIK, how to ensure that after security while reducing the incidence of Haze to determine the corneal flap substrate surface may be cutting depth, so that patients with high myopia better uncorrected visual acuity and visual quality is still to be our in-depth study.
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