Journal of Refractive Surgery

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LASIK COMPLICATIONS 

Efficacy and Safety of LASIK in 10,052 Eyes of 5081 Myopic Chinese Patients

Lanping Sun, BS; Guifen Liu, BS; Yanjun Ren, MD; Ji Li, MD; Junhua Hao, MD; Xia Liu, BS; Yajuan Zhang, MD

Abstract

ABSTRACT

PURPOSE: To analyze the outcomes and incidence of postoperative complications in a large series of patients undergoing LASIK for myopia.

METHODS: All 5081 patients (10,052 eyes) diagnosed with myopia at The Third Hospital of Handan, China, from September 2003 through March 2005 were studied. All study eyes underwent LASIK with 1-month follow-up. Spherical equivalent refraction, best spectacle-corrected visual acuity (BSCVA), and uncorrected visual acuity (UCVA) were measured before and after surgery and intra- and postoperative complications were recorded.

RESULTS: Uncorrected visual acuity at 1-month follow-up of 9555 (95.1%) eyes reached or exceeded the preoperative BSCVA. Hemorrhage of corneal limbus during surgery occurred in 1060 (10.5%) eyes, Sands of Sahara syndrome occurred in 232 (2.3%) eyes, interface infection responsive to treatment occurred in 4 (0.04%) eyes, and epithelial ingrowth occurred in 1 (0.01%) eye.

CONCLUSIONS: LASIK is a safe and effective method for the treatment of myopia. [J Refract Surg. 2005;21(Suppl):S633-S635.]

Abstract

ABSTRACT

PURPOSE: To analyze the outcomes and incidence of postoperative complications in a large series of patients undergoing LASIK for myopia.

METHODS: All 5081 patients (10,052 eyes) diagnosed with myopia at The Third Hospital of Handan, China, from September 2003 through March 2005 were studied. All study eyes underwent LASIK with 1-month follow-up. Spherical equivalent refraction, best spectacle-corrected visual acuity (BSCVA), and uncorrected visual acuity (UCVA) were measured before and after surgery and intra- and postoperative complications were recorded.

RESULTS: Uncorrected visual acuity at 1-month follow-up of 9555 (95.1%) eyes reached or exceeded the preoperative BSCVA. Hemorrhage of corneal limbus during surgery occurred in 1060 (10.5%) eyes, Sands of Sahara syndrome occurred in 232 (2.3%) eyes, interface infection responsive to treatment occurred in 4 (0.04%) eyes, and epithelial ingrowth occurred in 1 (0.01%) eye.

CONCLUSIONS: LASIK is a safe and effective method for the treatment of myopia. [J Refract Surg. 2005;21(Suppl):S633-S635.]

Laser in situ keratomileusis (LASIK) has been widely used in China to treat ametropia; approximately 500,000 eyes undergo surgery every year. Unfortunately, most reports do not focus on intra- and postoperative complications. Laser vision correction was performed on 10,399 eyes of 5256 patients from September 20, 2003 to March 20, 2005, including eyes with high, medium, and low myopia. Laser in situ keratomileusis was performed on 10,052 eyes and laser subepithelial keratomileusis (LASEK) was performed on the remaining 347 eyes.

PATIENTS AND METHODS

PATIENTS

This study comprised 10,052 eyes of 5081 patients (2456 men and 2625 women). Average patient age was 24.87±5.97 years. Preoperatively, uncorrected visual acuity (UCVA) ranged from 20/30 to 20/2000, best spectacle-corrected visual acuity (BSCVA) ranged from 20/15 to 20/100, spherical equivalent refraction ranged from -0.75 to -17.00 diopters (D) (mean: -5.65±2.32 D), and cylinder ranged from 0 to -5.50 D. Patients with ocular diseases were excluded from the study. Based on preoperative refraction, the study population was separated into four groups - low, medium, high, and very high (Table 1).

A complete ophthalmic examination was performed on each eye preoperatively, which included ocular dominance testing, UCVA, BSCVA, slit-lamp examination, direct and indirect ophthalmoscopy with scleral depression and threemirror contact lens evaluation, tonometry, OPD-Scan (which includes simultaneous refractometry, keratometry, corneal topography, and wavefront analysis), corneal thickness measurement, and Schirmer's testing. Preoperatively, 4224 eyes of 2112 patients were randomly chosen for chart review for evidence of fundus disease. Of these eyes, 283 (6.7%) required treatment prior to surgery (Table 2).

Table

TABLE 110,052 Eyes That Underwent LASIK for Myopia Separated into Groups According to Preoperative Spherical Equivalent Refraction

TABLE 1

10,052 Eyes That Underwent LASIK for Myopia Separated into Groups According to Preoperative Spherical Equivalent Refraction

The equipment used in the study included the NIDEK EC-5000 CXII excimer laser system, NIDEK MK2000 microkeratome system, the AOS-1100 workstation, ARK710A autorefractive keratometer, NT3000 non-contact tonometer, ARK-10000 OPD-Scan, and the UP-1000 ultrasonic pachymeter (NIDEK, Gamagori, Japan).

The surgical procedure was performed using oxybuprocaine as surface anesthesia. Patients who had been contact lens wearers were instructed to use Naphcon A (Alcon, Ft Worth, Tex) tid preoperatively. The corneal flaps were created with an 8.5-mm ring and the 130-?p? keratome head. Refractive power and corneal thickness were used to determine the diameter and depth of the laser ablation for each patient. Following creation of the flap, the excimer laser was used to ablate stromal tissue under the flap with an optical zone of 4.0 to 6.0 mm and transition zone from 5.0 to 6.5 mm. The central ablation depth performed in the study ranged from 20.5 to 195 pm, calculated to leave a minimum residual thickness of ^280 pm in the corneal bed. After the ablation, the flap was rinsed with balanced salt solution (BSS), replaced, and dried. Finally, Tarivid eye drops (Santen Pharmaceutical Co, Osaka, Japan) were given and eye shields placed for 24 hours. The postoperative medication regimen included 0.1% fluorometholone (qid for 1 week, tid for 2 days, bid for 2 days, and qd 2 days), Tarivid (qid 2 weeks), and AiIi eye drops (Santen Pharmaceutical Co) (qid for 1 to 3 months).

RESULTS

Most patients experienced a slight foreign body sensation and photophobia after LASIK, but these symptoms were generally gone within 6 hours. Among 9747 eyes with BSCVA ≥20/25 preoperatively, UCVA was the same or better than preoperative BSCVA in 95.1% (9555 eyes) at 1-month follow-up (Table 3). Refractive amblyopia with preoperative BSCVA <20/30 was noted in 305 (3.03%) eyes. After surgery, 128 (42%) of these eyes had improvement in BSCVA. Among these eyes, the BSCVA improved by 1 line in 12%, 2 lines in 10%, 3 lines in 17%, and ≥4 lines in 3%.

Intra- and postoperative complications occurred in some of the eyes. Intraoperative peri-limbal hemorrhage occurred in 1060 (10.6%) eyes. This was more common in contact lens wearers and patients with small diameter corneas.1 We observed during the study that the preoperative use of Naphcon A can decrease the risk of intraoperative hemorrhage. Some cases of sub-flap interface debris were observed following surgery. These flaps were treated by irrigating the flap with BSS.

Postoperatively, diffuse lamellar keratitis occurred in 232 (2.3%) eyes. All eyes responded to administration of topical corticosteroids without progression to scarring. Interface infection occurred in 4 (0.04%) eyes of 2 patients. One patient developed bilateral symptoms 2 days after LASIK and the other 3 days after LASIK. Best spectacle-corrected visual acuity returned to 20/20 in both eyes in one patient and 20/25 in both eyes in the other patient. Epithelial ingrowth requiring intervention by lifting and scraping the flap occurred in 9 (0.09%) eyes. All 9 eyes returned to 20/20 BSCVA by 10-month follow-up.

DISCUSSION

Laser in situ keratomileusis for myopia has been accepted by ophthalmologists and patients alike and is used routinely because of its effectiveness, predictability, and safety.2 Laser in situ keratomileusis results in a rapid visual recovery because the corneal epithelium and Bowman's membrane are left intact. Fortunately, postoperative complications are uncommon and typically treatable. The eye tracking and newer laser delivery systems have resulted in a decreased frequency of complications such central islands and eccentric ablations.

Surprisingly, the frequency of fundus disease diagnosed at the preoperative examination was similar amongst low and medium myopes as it was in very high myopes. In fact, eyes in the low myopia group were most likely to be diagnosed with retinal detachment at the preoperative examination. Hemorrhage of the fundus was not found preoperatively. However, diagnosis of peripheral retinal holes was common in our myopic cohort. We attribute our ability to accurately diagnose peripheral retinal disease to the use of indirect ophthalmoscopy and three-mirror contact lens examination3,4 in every patient preoperatively.

Table

TABLE 2Frequency of Fundus Disease in 10,052 Eyes That Underwent LASIK for MyopiaTABLE 3UCVA 1 Month After LASIK in 10,052 Eyes That Underwent LASIK for Myopia

TABLE 2

Frequency of Fundus Disease in 10,052 Eyes That Underwent LASIK for Myopia

TABLE 3

UCVA 1 Month After LASIK in 10,052 Eyes That Underwent LASIK for Myopia

Interface infection occurred bilaterally in 2 female patients with a history of contact lens wear who had surgery on the same day. Of the 30 patients to have surgery that day, no other patient developed an infection. The preoperative preparation, equipment, and surgical procedure were identical in all patients. Because of this, we suspect that these infections were related to contact lens wear and unique immunologic circumstances in these 2 patients rather than surgical technique. As a result of these infections, we believe it is important to use preoperative antibiotics and one set of blades and equipment per eye.56 Careful observation and aggressive treatment of suspected infections with interface irrigation with antibiotic and pathologic examination of infiltrates are important in maintaining vision after the diagnosis of an infection.

Refractive amblyopia is most commonly seen in patients with high degrees of myopia, especially when the refractive error was not treated at a young age. In this study, many of the refractive amblyopes (42%) had an improvement in BSCVA following surgery.

In our series, the use of the NIDEK MK-2000 microkeratome system allowed for creation of excellent flaps with minimal complications. This keratome is easy to operate, especially for beginning surgeons, because of the lack of on-eye assembly. The other benefit espoused by many authors is that the nasal hinge created by the MK-2000 decreases the rate of postoperative dry eye over superior hinged keratomes.

Laser in situ keratomileusis is safe and effective for all degrees of myopia. The predictability of LASIK with our technique is demonstrated by the fact that 95.1% of eyes in our study had postoperative UCVA better or equal to preoperative BSCVA.

REFERENCES

1. Chan WK, Weissman BA. Corneal pannus associated with contact lens wear. Am J Ophthalmol. 1996;121:540-546.

2. Lu WX. Zhunfenzi Jiguang Quguangxing Jiao Moshoushuxue. Beijing, China: Scientific and Technical Documents Publishing House; 2000.

3. Pan YF, Yang CC, Wang JP, Ling W. Retinal complications after excimer laser in keratomileusis. Zhongguo Shiyong Yanke Zazhi. 2000;18:493-494.

4. Du ZY, Tao D, Guo H, Zheng Q. Analysis of retinal complications before excimer laser in keratomileusis. Zhongguo Shiyong Yanke Zazhi. 2005;23:281-283.

5. Liang QF, Zhou YH, Li R, Wang ZJ, Luo SY, Sun XG. Bacteriological analysis on conjunctival sac of preoperative patients undergoing laser in situ keratomileusis. Zhongguo Shiyong Yanke Zazhi. 2005;23:403-405.

6. Freitas D, Alvarenga L, Sampaio J, Mannis M, Sato E, Sousa L, Vieira L, Yu MC, Martins MC, Hoffling-Lima A, Belfort R Jr. An outbreak of Mycobacterium chelonae infection after LASIK. Ophthalmologjr. 2003;110:276-285.

TABLE 1

10,052 Eyes That Underwent LASIK for Myopia Separated into Groups According to Preoperative Spherical Equivalent Refraction

TABLE 2

Frequency of Fundus Disease in 10,052 Eyes That Underwent LASIK for Myopia

TABLE 3

UCVA 1 Month After LASIK in 10,052 Eyes That Underwent LASIK for Myopia

10.3928/1081-597X-20050902-15

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