PURPOSE: To evaluate visual outcome and the changes of contrast sensitivity (CS) after diffuse lamellar keratitis (DLK). METHODS: Using retrospective chart review, 48 eyes of 25 patients who underwent laser in situ keratomileusis (LASIK) with Visx S4 (VISX Inc., Santa Clara, CA) and M2 (Moria, France) and who were followed for at least six months were included. They were divided into two groups: DLK and non-DLK, by diagnosis of DLK or its absence after LASIK. Postoperative logMAR visual acuities and logCS measured using the VCTS(R) 6500 (Vistech Consultants, Inc., Dayton, OH) were compared with preoperative values in the DLK and non-DLK groups at three and six months after LASIK. RESULTS: There was no difference in logMAR visual acuity between the DLK and non-DLK groups until the sixth postoperative month. However, CS was significantly decreased at 12 and 18 cycle/degree compared with preoperative values (p=0.043 and p=0.045, respectively) in the DLK group, whereas CS was significantly increased at 12 cycle/degree in the non-DLK group (p=0.042) at six months. CONCLUSIONS: DLK seemed to be strongly associated with a postoperative decrease of CS.
*Visual Acuity ; Retrospective Studies ; Keratomileusis, Laser In Situ/*adverse effects ; Keratitis/*etiology/*physiopathology ; Humans ; *Contrast Sensitivity ; Adult

Laser keratomileusis and excimer laser photorefractive keratectomy in situ are widely used therapies for treating myopia. The corrections of refractive error by glasses or contact lens result in a relatively equal refractive correction on both eyes. However, refractive surgery on a single eye can cause a focus disparity between both eyes and may result in the impairment of fusion leading to strabismus. This article aims to report a case where diplopia and esotropia occurred 1 month after laser keratomileusis (LASIK) in situ for the correction of myopia.
Adult ; Case Report ; Diplopia/etiology* ; Esotropia/etiology* ; Female ; Human ; Keratomileusis, Laser In Situ/adverse effects* ; Myopia/surgery ; Reoperation ; Treatment Outcome

To report a patient who presented with epithelial ingrowth caused by viral keratoconjunctivitis 3 months after LASIK surgery. A 41-year-old man presented with decreased visual acuity in the right eye, which had developed about 3 weeks before. He had undergone LASIK surgery 3 months prior without complications. Two months after the surgery, he was treated for viral conjunctivitis. During the treatment period, filamentary keratitis developed, and a therapeutic bandage contact lens was applied for 2 weeks. Upon presentation, examination revealed a corrected visual acuity of 20/100 and irregular epithelial sheets under the edematous flap. The flap was lifted, and the in-grown epithelium was removed. The flap was repositioned with double continuous 10-0 nylon sutures. Post-operatively, the patient developed a mild diffuse lamellar keratitis that resolved rapidly with topical corticosteroid treatment. At 2 months, the corrected visual acuity was 20/20 without interface opacities. As the patient showed no complications prior to viral conjunctivitis, we suspect that the viral infection caused edema of the corneal flap, which caused epithelial ingrowth under the flap. Patients who have viral conjunctivitis after LASIK surgery should be examined carefully and managed with consideration of flap complications.
Adult ; Cell Proliferation ; Conjunctivitis, Viral/*etiology/*pathology ; Epithelial Cells/*pathology ; Humans ; Keratomileusis, Laser In Situ/*adverse effects ; Male

The accommodative function before and after laser in situ keratomileusis (LASIK) was observed, and the effect of LASIk on accommodation was investigated. In a prospective clinical trial, 48 myopic patients (96 eyes) subject to bilateral LASIK in Refractive Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology (China) from March 2006 to June 2006 were selected and studied. Refractions, accommodative range, amplitude of accommodative response and high frequency component (HFC) of accommodative microfluctuations were measured with NEDIK-730A before and one week and 30 days after operation. Dominant and non-dominant eyes were determined by hole-in-card method. It was found that all of the operative eyes showed an uncorrected visual acuity of 0.8 or better one week postoperatively, and 1.0 or better 30 days postoperatively. Compared with those preoperatively, accommodative range and HFC had no significant difference at first week and 30th day after operation in both dominant eyes and non-dominant eyes (P>0.05), but there was a significant difference in the amplitude of accommodative response/accommodative stimulus ratio (A/S) after operation (P<0.01), and no significant difference was found in accommodation between one week and 30 days postoperation. No ocular dominance's change was noted. There was no significant difference in accommodative function between dominant eyes and non-dominant eyes. It was suggested that LASIK produced no significant effect on accommodation.
Accommodation, Ocular/*physiology ; Keratomileusis, Laser In Situ/*adverse effects ; Myopia/*physiopathology ; Myopia/*surgery ; Postoperative Period ; Prospective Studies ; Young Adult

BACKGROUNDThe recent studies have shown that visual performance might be affected by the ocular aberration after the corneal refractive surgery, and try to minimize it. This study was to investigate the effects of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) on the higher order of wavefront aberration and analysis of their characteristics.

METHODThis prospective study involved 32 eyes with similar refractive powers (-5.0 D to -6.0 D preoperatively). LASIK and PRK were performed with the same parameters of 6 mm diameter optical zone and 7 mm diameter transition zone ablation. Wavefront aberrations were tested using a ray tracing technique preoperatively and 3 months postoperatively. Three measurements were obtained for each condition; the root mean squared wavefront error (RMS), values for overall wavefront aberrations and each order of the Zernike aberrations were analyzed using the Matlab software. The 2-tailed t test was used for statistical analysis.

RESULTSOverall higher order aberrations were increased from (0.550.26) microm preoperatively to (0.930.37) microm for PRK and (0.790.38) microm for LASIK postoperatively. This was a 1.69 fold increase in the PRK group (t = 3.95, P < 0.001) and a 1.43 fold increase in the LASIK group (t = 2.60, P < 0.05). At 3 months, the mean RMS value for higher-order (3rd to 6th) were significantly increased compared with the corresponding preoperative values (P < 0.05). The fourth order aberrations, spherical like aberration, were dominant by a 2.64 fold in PRK and a 2.31 fold in LASIK. Different influences of the PRK group and LASIK group were shown in the various zernike components. The statistically significant differences were seen in C(4)(0), C(4)(+4), C(5)(+1), C(5)(+3), C(5)(+5) and C(6)(+2) of the PRK group and C(3)(-3), C(4)(0), C(5)(-5), C(5)(+5), C(6)(-2) of the LASIK group, which represents a 7.42, 3.58, 9.21, 2.72 and 5.3 fold increases in PRK group, and 6.40, 10.80, 11.06, 3.47 and 6.09 fold increases in LASIK group, respectively. C(3)(-3) in LASIK was higher and C(5)(+1) and C(5)(+3) were lower than those in the PRK group. C(4)(0) (spherical aberration) values were similar between PRK and LASIK, however, C(3)(-1) and C(3)(1) (coma) in LASIK were higher than those in PRK, but these differences are of no statistical significance.

CONCLUSIONSPRK and LASIK may increase ocular higher-order aberrations, but they both have their own features. The difference between the two types of surgery may be correlated with the change of the corneal shape, the conversion of biodynamics, the healing of the corneal cut, and re-structured corneal epithelium and/or the stroma.

Adolescent ; Adult ; Cornea ; pathology ; Humans ; Keratomileusis, Laser In Situ ; adverse effects ; Lasers, Excimer ; Photorefractive Keratectomy ; adverse effects ; Postoperative Complications ; etiology ; Prospective Studies ; Vision Disorders ; etiology ; Visual Acuity

Adult ; Anti-Bacterial Agents ; therapeutic use ; Conjunctiva ; drug effects ; microbiology ; Female ; Humans ; Keratomileusis, Laser In Situ ; adverse effects ; methods ; Levofloxacin ; therapeutic use ; Male ; Povidone-Iodine ; therapeutic use ; Prospective Studies

To determine if the residual corneal stromal bed of 250 micrometer is enough to prevent iatrogenic keratectasia in laser in situ keratomileusis (LASIK), we studied 958 patients who underwent LASIK from April 2000 to October 2003 retrospectively. The estimated probabilities of the residual stromal bed, that was less than 250 micrometer, were calculated using the published flap thickness data of Moria C&B microkeratome. Then we calculated the ratio of the real incidence of keratectasia to the expected the percentage of the patients with less than 250 micrometer residual stromal bed in our study. Using the LASIK flap thickness data of Miranda, Kezirian and Nagy, the expected probabilities that the residual stroma would be less than 250 micrometer were 8.8%, 4.3% and 1.5% of the 1,916 eyes respectively, while keratectasia developed in both eyes (0.1%) of 1 patient in our study. The estimated ratio of the keratectatic eyes to eyes with less than 250 micrometer stromal bed were 1.2-6.9%. Compared to the number of eyes with residual stromal thickness less than 250 micrometer, the incidence of keratectasia was relatively low. The residual stromal bed thickness of more than 250 micrometer may possibly be safe, but further observations for long period are necessary.
Postoperative Complications/*prevention & control ; Middle Aged ; Keratomileusis, Laser In Situ/*adverse effects ; Iatrogenic Disease/*prevention & control ; Humans ; Dilatation, Pathologic ; Corneal Stroma/*pathology ; Corneal Diseases/etiology/*prevention & control ; Adult

Adult ; Female ; Humans ; Keratitis ; etiology ; microbiology ; pathology ; Keratomileusis, Laser In Situ ; adverse effects ; Mycobacterium Infections, Nontuberculous ; etiology ; pathology ; Mycobacterium chelonae ; isolation & purification ; Postoperative Complications ; etiology ; microbiology ; pathology

INTRODUCTIONThe aim of the study was to compare the visual performance of LASIK eyes measured using high-contrast logMAR letter charts under bright (photopic) and dim (mesopic) conditions.

MATERIALS AND METHODSA total of 46 subjects (35 +/- 8 years of age) undergoing LASIK procedures were recruited for the study. The best spectacle-corrected visual acuity (BSCVA) of each subject was measured using the high-contrast ETDRS logMAR chart under photopic and mesopic conditions at 3 visits: preoperative (Pre), 1 month postoperative (Post1) and 3 months postoperative (Post3). The differences in logMAR scores for the right eyes only were analysed for the Pre-Post1 (n = 46), Pre-Post3 (n = 18) and Post1-Post3 (n = 16) comparisons.

RESULTSThe logMAR scores of subjects were worse at the 1-month postoperative visit than preoperatively, and improvement in visual performance was seen at the 3-month postoperative visit. These changes in visual performance became more evident under mesopic conditions. The means and standard errors of the differences in logMAR scores for the Pre-Post3 (0.097 +/- 0.020) were slightly larger than those of the Pre-Post1 (-0.067 +/- 0.019) and Post1-Post3 (0.031 +/- 0.012) comparisons. Under mesopic conditions, the visual performance of the subjects was statistically significant for the 3 comparisons, but not under photopic conditions.

CONCLUSIONHigh-contrast logMAR chart performed under mesopic conditions has the potential to replace visual acuity measured under photopic conditions in providing more reliable representation of postoperative visual outcomes of LASIK eyes. Eye doctors should consider performing this vision test routinely to gauge the success of LASIK surgery.

Adult ; Contrast Sensitivity ; Female ; Humans ; Keratomileusis, Laser In Situ ; adverse effects ; Lighting ; Male ; Middle Aged ; Reproducibility of Results ; Vision Disorders ; diagnosis ; etiology ; Vision Tests ; methods ; Visual Acuity

To purpose of this study was to evaluate complications of unintended thin corneal flap in laser in situ keratomileusis (LASIK), such as visual acuity and myopic regression, at the one year follow-up. We performed a study on 54 eyes, i.e. 27 patients, having LASIK. The eyes were split into two groups, group one, 27 eyes with unintended thin corneal flap with a thickness of 100 microm or less, and as a control group, 27 eyes with a thickness of 110 microm or more. The average corneal flap thicknesses of the two groups were 88.89 +/- 8.07 microm and 132.70 +/- 19.58 microm, respectively. With regard to postoperative complications, there were no statistical differences between the groups for: foreign bodies in aspects of the interface, mild peripheral infiltration, superficial punctuate keratitis, myopic regression and decreased vision. The only complication showing any statistical difference between the two groups was the central corneal opacity. An unintended thin corneal flap, with an intact Bowman's layer, induced no significant postoperative complications. Central corneal opacity was apparent in 4 of the eyes in group one, so may be related with a thin corneal flap.
Adult ; Comparative Study ; Cornea/surgery ; Corneal Opacity/*etiology ; Follow-Up Studies ; Human ; Keratomileusis, Laser In Situ/*adverse effects ; Myopia/surgery ; *Postoperative Complications ; Surgical Flaps/*adverse effects ; Treatment Outcome ; Visual Acuity