Diffuse Lamellar Keratitis and Flap Margin Epithelial Healing After Laser in situ Keratomileusis

Five-Year Outcome of LASIK for Myopia

PURPOSE

To investigate the efficacy and safety of LASIK over a 5-year postoperative period.

DESIGN

Observational case series.

PARTICIPANTS

We examined 779 eyes in 402 patients with myopia or myopic astigmatism who underwent LASIK to correct their refractive errors and received regular postoperative assessments for 5 years.

METHODS

Postoperative examinations were performed 1 day; 1 week; 1, 3, and 6 months; and 1, 2, 3, 4, and 5 years after LASIK surgery.

MAIN OUTCOME MEASURES

We evaluated changes in uncorrected visual acuity (UCVA) (logarithm of the minimum angle of resolution [logMAR]), manifest refraction, best-corrected visual acuity (BCVA) (logMAR), intraocular pressure, corneal thickness, corneal endothelial cell counts, and complications.

RESULTS

Preoperative UCVA of 1.27 improved to -0.03 at 1 day after surgery and -0.08 at 1 month and revealed minimal but significant decreases thereafter. Postoperative manifest refraction was also improved by surgery, showing minimal but significant regression after 1 year. Final BCVA loss was seen in 10 eyes of 7 patients; in 7 cases, there were obvious reasons such as the progression of cataracts in 3 eyes, epithelial disintegrity due to dry eye in 2 eyes, irregular astigmatism due to flap striae in 1 eye, and age-related macular dystrophy in 1 eye. Intraocular pressure and corneal thickness decreased by 4.0 mmHg and 76.9 microm, respectively, due to surgery, but remained stable throughout the follow-up period. Corneal endothelial cell counts (2689.0+/-232.9 cells/mm(2) before surgery) showed a statistically significant decrease at 5 years after surgery (2658.0+/-183.1 cells/mm(2); 1.2% loss for 5 years), likely within the range due to physiological age-related loss. No serious, vision-threatening, irreversible complication such as keratectasia or progressive endothelial cell loss was observed.

CONCLUSION

LASIK surgery is an effective and safe procedure for correcting myopia/myopic astigmatism as long as inclusion and exclusion criteria are strictly respected. However, minimal regression occurred during the 5-year investigative period.

Detection of neutrophils in late-onset interface inflammation associated with flap injury after laser in situ keratomileusis

OBJECTIVE

To report a case with late-onset interface inflammation associated with traumatic flap injury at 7 months after laser in situ keratomileusis (LASIK) and to describe the type of infiltrating cells in the tears of the patient.

METHODS

Interventional case report. A 24-year-old male patient who underwent uneventful LASIK on both eyes received blunt trauma from the tip of a shoe in the left eye 7 months after surgery. The corneal flap of his left eye was lacerated across the pupillary area. Inflammatory cells were observed under the lacerated flap segment. Tear fluid was collected from his left eye 3 days after the injury and assessed by tear cytology. For controls, tears of 2 patients who underwent LASIK and developed no interface inflammation were collected the next day after their surgeries and examined.

RESULTS

Tear fluid of the patient with interface inflammation contained numerous neutrophils. Tears of control patients contained only a few epithelial cells and cell debris but no inflammatory cells. The inflammation was decreased by systemic and topical steroids. However, irregular astigmatism caused by stromal scarring remained, resulting in decreased best-corrected visual acuity.

CONCLUSIONS

Interface inflammation can be caused by late-onset flap injury. Neutrophils detected in the tears may reflect a major component of cells infiltrating the interface after LASIK.

Ocular Surface Treatment Before Laser in situ Keratomileusis in Patients With Severe Dry Eye

PURPOSE

To evaluate the efficacy and safety of laser in situ keratomileusis (LASIK) in patients with severe dry eye associated with Sjögren's syndrome.

METHODS

Three patients (six eyes) with Sjögren's syndrome who underwent bilateral LASIK were retrospectively evaluated for visual outcome, intraoperative and postoperative complications, dry eye status (subjective symptoms and objective findings, Schirmer test, vital staining of the ocular surface), and outcome satisfaction by subjective questionnaire. All patients had negative reflex tearing and were treated with topical autologous serum and/or punctal occlusion prior to LASIK to improve the ocular surface. This treatment was continued postoperatively.

RESULTS

Mean attempted correction of six eyes was -8.46 +/- 1.55 D (range -7.00 to -10.63 D). One year after LASIK, mean uncorrected visual acuity was 1.07 (range 0.7 to 1.5), mean best spectacle-corrected visual acuity was 1.29 (range 1.2 to 1.5), and mean refraction was -0.19 +/- 0.51 D (range -1.00 to +0.50 D). Tear production, rose bengal and fluorescein staining, and dry eye symptoms were not exacerbated after LASIK. No complications, such as intraoperative epithelial defect, diffuse lamellar keratitis, epithelial ingrowth, or recurrent erosion occurred. All three patients were satisfied with the outcome of their surgery.

CONCLUSION

LASIK can be safely and effectively managed in patients with severe dry eye with reduced reflex tearing by preoperative and postoperative treatments consisting of a combination of artificial tears, topical autologous serum, and punctal occlusion. Careful assessment of preoperative and postoperative ocular surface status is mandatory in such patients.

Keratocyte activation and inflammation in diffuse lamellar keratitis after formation of an epithelial defect

PURPOSE

To examine the inflammatory reaction in acute or late-onset post-laser in situ keratomileusis (LASIK) diffuse lamellar keratitis (DLK) associated with an epithelial defect.

SETTING

Department of Ophthalmology, Helsinki University Central Hospital, Helsinki, Finland.

METHODS

Six consecutive LASIK patients presented with stage 2 to 3 unilateral DLK 1 to 4 days after formation of an epithelial detachment (intraoperatively or up to 19 months postoperatively). Five corneas of 5 DLK patients, 1 eye twice, were examined by corneal in vivo confocal microscopy 1 to 8 days after the appearance of the epithelial defect. Confocal microscopy of conjunctival venules was performed in 2 of 6 DLK patients to quantify leukocyte rolling and extravasation. Corneas of 5 patients and conjunctival venules of 4 patients who had uneventful LASIK served as controls.

RESULTS

Two of the 4 patients examined 0 to 1 day after the onset of DLK presented with small objects, presumably inflammatory cells (diameter 6.0 to 10.0 microm), in the LASIK flap interface. A third patient examined 1 day after the onset of DLK had larger objects (approximately 13.0 microm in diameter) in the interface. Three other cases (1 to 7 days after the onset of DLK) showed changes typical of keratocyte activation and altered extracellular matrix. All cases healed completely following treatment with steroids. Control LASIK subjects showed some keratocyte activation on day 5.

CONCLUSIONS

Neither uneventful LASIK nor DLK induced an inflammatory reaction displaying leukocyte rolling in conjunctival venules or extravasation into the conjunctival stroma. Diffuse lamellar keratitis related to an epithelial defect does not always lead to the appearance of inflammatory cells in the flap interface. The corneal manifestations of epithelial defect-related DLK may originate from sterile epithelial-stromal or inflammatory cell-stromal cell interactions, leading to alteration of the keratocyte phenotype.

Risk Factors for Development of Diffuse Lamellar Keratitis After Laser in situ Keratomileusis

PURPOSE

To investigate the risk factors and mechanisms of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

METHODS

In 5708 eyes of 2927 patients who underwent LASIK, the patient's background, clinical findings, and surgical data were retrospectively evaluated and compared with patients who had DLK and those who did not (non-DLK group).

RESULTS

DLK occurred in 46 of 5708 eyes (0.81%). DLK occurred more frequently in eyes operated with the MK-2000 microkeratome (1.1%) than with the LSK-One microkeratome (0.6%; P = .039). Corneal endothelial cell density (2686.8 +/- 235.3/mm2) was significantly lower in eyes that developed DLK than in eyes without DLK (2783.8 +/- 275.5/mm2; P = .017). The width of palpebral fissure in a normal state and the maximum opening position were significantly larger in the DLK group (10.3 +/- 1.9 mm and 18.1 +/- 7.2 mm, respectively) than the non-DLK group (8.3 +/- 1.6 mm with P < .001; 11.5 +/- 2.0 mm with P = .012).

CONCLUSIONS

The type of microkeratome, lower corneal endothelial cell density, and larger palpebral fissure were potential risk factors for DLK after LASIK. These factors may be associated with delayed wound healing of the corneal flap margin, resulting in poor sealing of the flap, which may induce the influx of inflammatory cells.

Detection of neutrophils and possible involvement of interleukin-8 in diffuse lamellar keratitis after laser in situ keratomileusis

PURPOSE

To investigate the cell populations in diffuse lamellar keratitis (DLK) infiltration after laser in situ keratomileusis and the possible mechanism underlying the infiltration.

SETTING

Department of Ophthalmology, Tokyo Dental College, Chiba, Japan.

METHODS

To develop DLK in rabbit eyes, 25 microL of lipopolysaccharide (LPS) solution at a concentration of 50 microg/mL was applied to the stromal bed beneath corneal flaps. For control rabbits, phosphate-buffered saline was applied. Postoperative examination by slitlamp microscopy was performed for 3 days after surgery. Rabbit eyes were excised and examined for histopathology with hematoxylin and eosin staining. Immunohistochemical analysis for interleukin (IL)-8 was performed.

RESULTS

Diffuse lamellar keratitis-like inflammation composed mainly of neutrophils was reproduced by LPS instillation in rabbit eyes. In eyes with severe inflammation, IL-8 immunoreactivity was found in the stromal keratocytes and infiltrating neutrophils.

CONCLUSIONS

The major cell type in the DLK infiltration induced by LPS instillation in rabbit eyes was the neutrophil. Interleukin-8, a prototype of CXC chemokine produced by keratocytes and neutrophils, may contribute to the development of DLK.