Delayed-onset mycobacterial keratitis after LASIK

PURPOSE: To describe the time course, diagnosis, clinical features, and treatment of seven patients with Mycobacterium szulgai keratitis that developed from 7 to 24 weeks after laser in situ keratomileusis (LASIK). METHODS: Seven of 30 eyes of 18 patients were identified with keratitis after LASIK. The first two patients presented 12 to 14 weeks after LASIK; nontuberculous mycobacteria were identified 1 month after the flaps were cultured. Patient recall identified three additional cases by culture and two cases by clinical features alone. Pulsed-field gel electrophoresis (PFGE) was used to type the isolates, and treatment was modified based on susceptibilities. RESULTS: M. szulgai was identified in five patients for whom cultures were performed, but response to empiric therapy based on cultures proved unsatisfactory. The keratitis resolved in all patients with treatment including clarithromycin based on susceptibilities. Medical therapy was sufficient, although one patient required flap amputation. Six of seven patients recovered best-corrected visual acuity (BCVA), while one patient lost one line of BCVA. Two patients lost one line of postoperative uncorrected visual acuity (UCVA), two patients gained one line of UCVA, and three patients recovered postoperative UCVA. PFGE analysis revealed that the M. szulgai strains were identical, and the infection source was contaminated ice used to chill syringes for saline lavage. CONCLUSIONS: Nontuberculous mycobacterial keratitis after LASIK is a diagnostic and management challenge, but outcomes can be preserved with treatment based on susceptibilities. This cluster underscores the importance of adherence to sterile protocol during LASIK.     

Sporadic diffuse lamellar keratitis (DLK) after LASIK

PURPOSE: To examine the incidence of sporadic diffuse lamellar keratitis (DLK) in a large series of LASIK eyes and to suggest the hypothesis that the etiology of sporadic DLK differs from that of epidemic DLK. METHODS: The incidence and severity of DLK was noted in 1352 consecutive eyes that had primary LASIK for myopia or hyperopia and 217 consecutive eyes that had LASIK enhancement. RESULTS: Twelve of the eyes having primary LASIK had stage 1 DLK and 5 had stage 2 DLK (.9% total). No eyes had stage 3 or stage 4 DLK. Three of the 217 eyes (1.4%) that had LASIK enhancement had stage 1 DLK. The difference in the rate of DLK for primary LASIK compared with LASIK enhancement was not statistically significant (p = 0.69). All eyes responded to intensive corticosteroid therapy, with the addition of flap lifting and irrigation for the eyes with stage 2 DLK. Two of the eyes (one primary LASIK and one LASIK-enhancement) had implanted epithelial nests associated with the DLK. None of the cases of DLK occurred in eyes of patients who had surgery on the same operating day in this series. Two other eyes that had epithelial abrasions more than 3 months after LASIK or LASIK enhancement developed stage 1 DLK. CONCLUSIONS: Many cases of sporadic DLK, including cases associated with epithelial trauma after LASIK, are likely attributable to endogenous factors that trigger inflammation. One trigger is the release of epithelium-derived cytokines such as interleukin-1 that stimulate keratocytes to produce chemokines that are chemotactic to inflammatory cells. Cells likely accumulate at the interface because it is potential space, representing a path of least resistance for cell movement. Some sporadic cases may also be related to exogenous factors such as Betadine. Epidemic DLK is likely associated with exogenous factors that stimulate inflammation, such as endotoxin contaminating sterilizer reservoirs or detergents on instruments.     

Nontuberculous mycobacterial keratitis: report of two cases causing infectious crystalline keratopathy

We report two cases of nontuberculous mycobacterial keratitis, occurring after corneal trauma with superficial foreign body and after perforating keratoplasty for alkali burn, respectively. Patients initially presented with indolent white corneal infiltrates, which did not respond to topical treatment. Both secondarily developed infectious crystalline keratopathy with unequal intensity. In the first case, the excised flap of lamellar keratectomy was cultured, allowing identification of Mycobacterium abscessus. Mycobacterium chelonae was isolated from a corneal biopsy in the second case. The clinical course showed poor response to antibiotic therapy consisting of ciprofloxacin and amikacin drops in conjunction with a new-generation oral macrolide. Corneal infection recurred after lamellar keratectomy in the first patient. Topical corticosteroid interruption burst corneal inflammation and induced stromal necrosis in the other patient. These intractable mycobacterial infections were finally controlled with penetrating keratoplasty. Our data suggest that a rapidly growing mycobacteria culture is required when clinical presentation consists of chronic bacterial keratitis or infectious crystalline keratopathy.     

Diffuse interface keratitis after laser in situ keratomileusis (LASIK): a nonspecific syndrome

PURPOSE: To characterize the presentation of diffuse interface keratitis after laser in-situ keratomileusis (LASIK). METHODS: Case report. RESULTS: Diffuse interface keratitis occurred in the left eye of a postoperative LASIK patient after central epithelial debridement without exposure of the flap margin or elevation of the flap. CONCLUSION: Diffuse interface keratitis is a nonspecific presentation of corneal inflammation after LASIK, with accumulation of inflammatory cells in the potential space of the interface. Diffuse interface keratitis after LASIK may have multiple causes.     

Diagnosis and treatment of mycobacterial keratitis following LASIK. Case report and review of the literature

BACKGROUND: Mycobacterial keratitis is a rare complication following LASIK but can lead to an extremely unfavourable outcome. The diagnosis and treatment is often delayed due to confusion with other entities including diffuse lamellar keratitis and poor clinical outcomes with flap amputation and/or keratoplasty are often the case. PATIENT AND METHODS: We report the results of LASIK in a 51-year-old woman with subsequent early-diagnosed mycobacterial keratitis and compared this case to treatments and outcomes reported in the literature. RESULTS: The patient presented 10 days following LASIK with a white focal infiltrate in the stromal interface. The flap was lifted and cultures from the stromal bed and the reverse of the flap were obtained and the interface irrigated. The patient was treated with topical antibiotics (ciprofloxacin 0.3%, amikacin 2.5%, clarithromycin 40 mg/ml and tobramycin 15 mg/ml) for 8 weeks and at the most recent follow-up she had a visual acuity of 1.25. CONCLUSION: In a large number of published cases in the literature the flap had to be amputated and/or corneal transplants were necessary. Early diagnosis and treatment however, are essential to successfully treat post-LASIK keratitis. Therefore the patients should be followed up carefully in the early postoperative period.     

Unilateral fungal and mycobacterial keratitis after simultaneous laser in situ keratomileusis

PURPOSE: To report a case of unilateral fungal and mycobacterial keratitis after simultaneous laser in situ keratomileusis (LASIK). METHODS: Case report of a 37-year-old woman who developed corneal infiltrates located at the flap-stroma interface in her left eye 3 weeks after LASIK for myopia. The infiltration progressed despite topical antibiotic therapy; therefore, the flap was lifted and irrigated with antibiotic solution. Parallel corneal scrapings were taken. The patient's condition deteriorated, prompting a lamellar keratoplasty. RESULTS: Corneal scrapings demonstrated no growth. Microbiologic cultures of the corneal specimen were reported as negative, whereas histopathologic examination disclosed fungal filaments. Two months later, the patient presented corneal infiltrates of the left eye again. Because the situation worsened despite therapy, a penetrating keratoplasty was performed. Histopathologic examination of the host cornea revealed no pathogenic species; microbiologic cultures, however, demonstrated Mycobacterium chelonae. CONCLUSION: Fungi and M. chelonae are rare and insidious causes of infectious keratitis after LASIK. Our case emphasizes the possible difficulties in diagnosing and treating a combined or subsequent infection with both species.     

Rapid diagnosis and treatment of mycobacterial keratitis after laser in situ keratomileusis

We report the results of laser in situ keratomileusis (LASIK) in a 51-year-old woman with subsequent mycobacterial keratitis diagnosed by staining with acid-fast and fluorochrome methods, a technique known to have good sensitivity and specificity for mycobacteria. A rapid diagnosis was made without waiting for cultures, and treatment was instituted, including tapering of topical steroids and appropriate antibiotic therapy. The result was preservation of the LASIK flap and a favorable visual outcome at 6 months.     

Rapid progression of amebic keratitis 1 week after corneal trauma and 1 year after LASIK

PURPOSE: To report a case of amebic keratitis that showed unusually rapid clinical progression after corneal trauma in a patient 1 year after successful laser in situ keratomileusis (LASIK) surgery. METHODS: A 42-year-old pilot with a previous history of 20/20 uncorrected vision 1 year after LASIK surgery developed a clinical picture suggestive of acute microbial keratitis 7 days after the eye was traumatized by an ice chip. The correct diagnosis of amebic keratitis was confirmed by tissue biopsy 17 days after initial trauma when rapid progression of the keratitis necessitated excision of the LASIK flap. RESULTS: Pathology from the excised LASIK flap showed a mean of 30 amebic cysts per high power field. Thirty-three days after beginning 0.02% polyhexamethylene biguanide every hour, the patient developed culture negative hypopyon and an endothelial inflammatory plaque. Six months after starting antiamebic treatment, he developed sterile iris nodules and focal hemorrhages in the anterior chamber. Penetrating keratoplasty revealed persistence of amebic cysts in the anterior corneal stroma. Fifteen months after his initial injury, his vision remains hand motion. CONCLUSIONS: Amebic keratitis presented atypically and progressed rapidly to a stage of severe ring infiltrate within 10 days of trauma in a patient whose only risk factor was a history of uncomplicated LASIK more than 1 year before the trauma. Amebic keratitis should be included in the differential diagnosis of rapidly progressive corneal ulcer after trauma in patients with a history of LASIK.     

我国真菌性角膜炎的研究现状

真菌性角膜炎发病率逐年增高，致盲率居高不下，临床治疗棘手。早期诊断、及时治疗可明显改善预后。近年来，随着对真菌性角膜炎认识的提高，早期正确诊断率有较大提高；利用分子生物学技术对真菌性角膜炎的快速诊断研究及分型诊断也取得了进展；组织病理学研究提示真菌的菌株不同、对角膜的感染方式以及在组织内的生长方式可能不相同；手术方式的探索也较大程度地改善了预后。为了更有效地治疗真菌性角膜炎，许多基础和临床工作还有待完成。     

Deep stromal mycobacterial keratitis: viable bacteria after six months of treatment: case report and literature review

To report the presence of viable mycobacteria in a patient with keratitis treated for 6 months. Species identification was performed using the PRA method (polymerase chain reaction followed by restriction endonuclease analysis). Clonality was evaluated with RAPD (randomly amplified polymorphic DNA) and ERIC-PCR (enterobacterial repetitive intergenic consensus-polymerase chain reaction) methods. The patient reported trauma due to a metallic foreign body 3 weeks prior to presentation. Initial corneal scraping cultures revealed Mycobacterium abscessus. After 6 months of topical and systemic treatment the patient presented with no active inflammation and was considered clinically cured. An optic penetrating keratoplasty was performed. Culture of the excised cornea revealed Mycobacterium abscessus. Both isolates had the same clonal origin. The most interesting finding of this case report was the positive culture of the excised cornea after 6 months of intensive specific topical therapy. To our knowledge, this is the first report in the literature showing this possibility in the treatment of Mycobacterial keratitis. Thus, Mycobacterium abscessus may present viable bacteria after long-term treatment and should be followed carefully for a long period of time after tapering the medication.     

The epithelial response in keratitis sicca and keratitis herpetica (an experimental and clinical study)

Summary The results of the histochemical stainings are summarised in Table 3a and b.The histological examination of the dry eyes shows the thickening and keratinisation of the superficial flattened cell layer of the corneal and con-junctival epithelium. There is generalised hypertrophy of the epithelium but in some places hydropic degeneration of the cells and atrophy is seen. The cells are irregularly arranged, sometimes forming a rosette. There is intercellular and intracellular oedema of the epithelium.A large number of Teng cells (Teng & Katzin, 1953; Teng, 1961, 1962) are seen in the corneal epithelium. These cells participate in the regeneration of the basement membrane of the epithelium. This membrane becomes irregular and wavy in keratitis sicca.In the basal and middle layers of the corneal epithelium and the deeper layers of the conjunctiva increased RNA activity is found.The histochemical stainings demonstrate intranuclear keratinisation and denaturation of DNA. These nuclei stain positive with alcian blue and PAS stains; negative or faintly positive with the Feulgen reaction; show ortho-chromasia instead of the metachromasia with toluidine blue metachromatic staining and give a positive reaction for the keratin.The activity of the acid phosphatase is increased in the epithelium.The cells of the corneal and conjunctival epithelium show intracytoplasmic deposits of heterogenous material composed of 0.1 elementary particles. These deposits show positive reactions for -SH groups and glycoproteins. This material presents an isotropic and anisotropic zones. Its density is variable and pleomorphic which progressively increases towards the superficial layers. These characteristics correspond to those of keratohyalin.The superficial keratinised layers of the corneal and conjunctival epithelium are disposed in lamellar fashion and give positive stainings for -SH groups and -S-S- bridges.In addition to the changes of keratinisation, progressive atrophy of the goblet cells is seen in the conjunctiva. These cells may entirely disappear in some areas. The submucosa shows subacute inflammatory cell infiltration and hyperaemia. In some cases it is found fragmented. Quite often a fibrinous deposit can be seen on the conjunctival surface.Slight oedema of the superficial layers of the corneal stroma is found which explains the feable stainings for mucopolysaccharides.Before discussing the implications of the histochemical and histological findings in relation to the clinical observations in keratoconjunctivitis sicca, we ought to take into account the results of electron microscopy. Discussion of the overall findings, therefore, follows in the section General discussion and conclusions'.This paper was originally submitted as a Doctor's Thesis to the Department of Ophthalmology, University of Leuven (Faculty of Medicine) in 1976.     

Description, etiology, and prevention of an outbreak of diffuse lamellar keratitis after LASIK

PURPOSE: To describe an outbreak of diffuse lamellar keratitis (DLK) and provide a hypothesis about the etiology. METHODS: A retrospective analysis was carried out on 328 eyes of 220 patients who underwent LASIK over 9 months. The occurrence of DLK using two different methods of cleaning and sterilizing surgical instruments and an autoclave reservoir were analyzed. Microbial analyses were carried out by two laboratories on samples obtained from the original autoclave reservoir and tubing. A chi-square test was used to compare qualitative values. The Student t test was used to compare numerical values. RESULTS: Forty-six (24.5%) of 188 cases of DLK were diagnosed. Sphingomona paucimobilis and Burkholderia pickettii were isolated in the reservoir of the steam sterilizer. Electron microscopy revealed gram-negative microbes on the tubing walls. After changing the reservoir of the steam sterilizer and implementing a new cleaning and sterilization protocol based on air-drying the instruments and draining and drying the reservoir of the sterilizer, the occurrence of DLK stopped. No statistically significant correlation was noted between the occurrence of DLK and gender, age, or volume of tissue removed. CONCLUSIONS: Data obtained during this DLK outbreak support the theory that a bacterial endotoxin, which can survive short-cycle steam sterilization, could be responsible for an outbreak of DLK. We recommend cleaning and sterilization protocols based on air-drying surgical instruments and leaving the reservoirs completely dry at the end of each surgical day.     

LASIK术后眼调节状态的改变及其与视疲劳的关系

目的探讨准分子激光原位角膜磨镶术（LASIK）对近视患者眼调节状态的影响,同时对眼调节状态的变化与视疲劳症状的关系进行探讨。方法回顾性研究。选取2009年3月至8月来东风总医院眼科行LASIK的双眼近视患者60例（120眼）,年龄18-35岁,术前等效球镜值为（-5．52±1．60）D,散光度〈2．00D．最佳矫正视力（BCVA）≥1．0。选择正视者20例（40眼）作为对照组。术前及术后1周、2周、1个月,分别对两组测定其单眼及双眼调节幅度,并对其进行近距工作视疲劳症状的问卷调查。采用独立样本t检验对两组的调节幅度和视疲劳评分进行比较,对近视组各时间点的调节幅度行单因素方差分析．并对术后1周调节幅度下降程度与术前屈光度的关系采用Pearson相关分析。结果①调节状态：LASIK术后第1周,近视组单眼及双眼调节幅度分别为（7．82±0．58）D和（8．10±0．54）D,较术前下降（P均〈0．05）,之后逐渐恢复,至术后1个月时超过术前水平,且与正视组相比差异无统计学意义。②视疲劳症状：LASIK术后第1周,近视患者视疲劳症状均较术前明显加重,之后症状逐渐减轻,至术后1个月时视疲劳症状较术前明显减轻。③相关性分析：术后1周时,调节幅度的降低程度与术前屈光度呈正相关（r=0．83,P〈0．01）;近视组视疲劳症状与双眼调节幅度呈负相关（r＝-0．79,P〈0．01）。结论LASIK术后患者视近时调节需求增加,且单眼及双眼调节幅度均有短暂下降,术后第1周显著下降,之后逐渐恢复。LASIK术后视疲劳症状和眼调节状态的变化有关。     

Retinal complications after laser-assisted in situ keratomileusis (LASIK)

PURPOSE OF REVIEW: This paper reviews the retinal complications that may occur after laser-assisted in situ keratomileusis (LASIK). RECENT FINDINGS: During the review period (1 year), several nonrandomized retrospective studies and case reports/series were published. One study was performed to determine the efficacy and safety of prophylactic laser photocoagulation for retinal breaks in patients with myopia undergoing LASIK. Retinal breaks were identified and treated in 39 eyes (2%). None of the patients developed a rhegmatogenous retinal detachment (RRD) (except one trauma case). Another group studied retinal disease observed in 9239 consecutive eyes after refractive surgery (including LASIK) and found RRD in 11 eyes (0.36%) and choroidal neovascularization (CNV) in 10 eyes (0.33%). Three reports described a total of 16 patients with a previously placed encircling scleral buckle for a RRD who had LASIK to correct myopia. In all patients, the visual acuity (VA) improved. Another study reported the characteristics and surgical outcomes of RRD in myopic eyes after LASIK (33 eyes of 27 patients; frequency 0.08% [33/38, 823]). They found that 45.8% lost two or more lines of VA after vitreoretinal surgery. Two letters described the characteristics and potential mechanisms of a macular lacquer crack (one with subsequent development of subfoveal CNV) in a myopic patients corrected by LASIK. SUMMARY: Serious complications after LASIK are infrequent. A dilated fundus examination is very important before LASIK and in every patient whose VA after LASIK is not as good as expected to avoid delayed referral to a vitreoretinal specialist if necessary. Only prospective studies can determine whether the procedure exacerbates myopic pathology.     

Corneal sensation after myopic and hyperopic LASIK: clinical and confocal microscopic study

AIM: To assess the long term (1 year) effect of myopic and hyperopic LASIK on corneal sensation and innervation. METHODS: 83 eyes of 43 patients having LASIK were evaluated. According to the preoperative spherical equivalent, the eyes were divided into three groups: group 1, myopia from -0.75 to -6.00 D; group 2, myopia from -6.25 to -11.50 D; and group 3, hyperopia from 1.25 to 5.00 D. Corneal sensation was measured and in vivo confocal microscopy (IVCM) was done at the central cornea before, and at 1 month, 3 months, 6 months, and 1 year after LASIK. RESULTS: The mean corneal sensation in group 1 was greater than in groups 2 and 3 at all postoperative measurements. The difference between group 1 on one hand and groups 2 and 3 on the other hand was statistically significant at 1 month and 3 months after LASIK and was not statistically significant afterwards. IVCM study of 27 eyes revealed that the number and length of nerve fibre bundles in the sub-basal region decreased after LASIK and was significantly lower at all times after surgery despite the return of corneal sensation to preoperative level. CONCLUSION: After LASIK, central corneal sensitivity is decreased for as long as 6 months or more. The results suggest that lamellar cutting of the cornea during LASIK impairs corneal sensitivity and is related to the ablation depth. The diameter of ablation too may contribute to this drop in sensitivity. The return of corneal sensations does not directly correlate with the regeneration of nerve fibres as determined by confocal imaging. Sensations return to normal values before complete restoration of normal innervation if this indeed ever occurs.     

Intraoperative and postoperative complications after laser in situ keratomileusis (LASIK)

Purpose: To quantify the incidence and type of complications after LASIK for the correction of myopia with special consideration to the time lapse after surgery and the possible consequences regarding high-contrast sensitivity and other modalities of visual acuity. Material and methods: Between January 1995 and April 1997, 125 eyes of 88 patients with myopia greater than −6.0 D who could not wear contact lenses were operated on at our institute. In this prospective study the patients were examined consecutively preoperatively as well as postoperatively at day 4 and months 1, 3 and 6. The complications were divided into three groups (intraoperative, early postoperative and late postoperative). Results: Our complication rate was 7.2 % (loss of 2 lines of visual acuity) – with cutting artifacts related to the microkeratome, wrinkling of the flap and epthelial ingrowth. Conclusions: LASIK is a microsurgical procedure that requires adequate experience and the desire by the surgeon for self-evaluation. In spite of the good clinical results in the correction of high myopia the complication rates seems still to be too high. This should be the objective for further improvement primarily related to the microkeratomes.