In vivo confocal microscopic findings in patients with Steroid-Induced glaucoma after LASIK*1

Pressure-induced stromal keratopathy after laser in situ keratomileusis: Acute and late-onset presentations

We present a series of 4 cases of pressure-induced stromal keratopathy after laser in situ keratomileusis (LASIK). Four patients (5 eyes) with previous LASIK presented for poor visual acuity and ocular pain because of ocular hypertension. At examination, all cases revealed corneal haze and a space filled with fluid between the surgical flap and the residual stroma. All cases were managed with topical hypotensive treatment and one of them was also treated with a valve drainage device. Topical steroids restriction was indicated in all cases. Intraocular pressure (IOP) was normalized in all cases with subsequent interface fluid resolution and significant improvement of vision in most cases. Early recognition and appropriate treatment for pressure-induced stromal keratopathy is essential to avoid complications associated with prolonged elevated IOP. It is extremely important to measure the IOP in the peripheral cornea because IOP in the central cornea can be incorrectly measured with the characteristic interface fluid developed in this entity.

Incidence of interface fluid syndrome after laser in situ keratomileusis in Egyptian patients

Purpose

To determine the incidence of interface fluid syndrome (IFS) secondary to steroid-induced elevation of intraocular pressure (IOP) following laser in situ keratomileusis (LASIK) in myopic Egyptian patients.

Methods

This retrospective case series study was conducted at El-Gowhara Private Eye Center. The medical records of 1,807 patients (3,489 eyes), who underwent LASIK to correct myopia from April 2012 to December 2015 were included. The patients were operated on and reviewed by one surgeon (AAG) for IFS after LASIK associated with elevation of IOP (as compared to preoperative values).

Results

This paper reports the incidence of 2.9% (54 patients) (102 eyes) of IFS induced by increased IOP after LASIK in Egyptian patients. The medical records of 1,807 patients (3,489 eyes) with mean age ± standard deviation (SD) 26.4±2.7 years, who presented with mean myopia ± SD −4.50±1.3 D, mean astigmatism ± SD −1.43±0.8, mean IOP ± SD 15.2±1.2 mmHg, and mean central corneal thickness ± SD 549±25.6 μm, were included. The preoperative anterior and posterior segments, corneal topography, and Schirmer’s test were unremarkable.

Conclusion

Limiting topical steroids and routinely measuring the IOP post-LASIK are necessary steps to prevent IFS, especially in case of myopia. A high index of suspicion is required to make a diagnosis. High-resolution optical coherence tomography is helpful to confirm the diagnosis.

LASIK interface complications: etiology, management, and outcomes

PURPOSE

To describe the etiology, diagnosis, clinical course, and management of LASIK interface complications.

METHODS

Literature review.

RESULTS

Primary interface complications include infectious keratitis, diffuse lamellar keratitis, central toxic keratopathy, pressure-induced stromal keratopathy (PISK), and epithelial ingrowth. Infectious keratitis is most commonly caused by Methicillin-resistant Staphylococcus aureus (early onset) or atypical Mycobacterium (late onset) postoperatively, and immediate treatment includes flap lift and irrigation, cultures, and initiation of broad-spectrum topical antibiotics, with possible flap amputation for recalcitrant cases. Diffuse lamellar keratitis is a white blood cell infiltrate that appears within the first 5 days postoperatively and is acutely responsive to aggressive topical and oral steroid use in the early stages, but may require flap lift and irrigation to prevent flap necrosis if inflammation worsens. In contrast, PISK is caused by acute steroid response and resolves only with cessation of steroid use and intraocular pressure lowering. Without appropriate therapy PISK can result in severe optic nerve damage. Central toxic keratopathy mimics stage 4 diffuse lamellar keratitis, but occurs early in the postoperative period and is noninflammatory. Observation is the only effective treatment, and flap lift is usually not warranted. Epithelial ingrowth is easily distinguishable from other interface complications and may be self-limited or require flap lift to treat irregular astigmatism and prevent flap melt.

CONCLUSIONS

Differentiating between interface entities is critical to rapid appropriate diagnosis, treatment, and ultimate visual outcome. Although initial presentations may overlap significantly, the conditions can be readily distinguished with close follow-up, and most complications can resolve without significant visual sequelae when treated appropriately.

[Complication cascade after hyperopic LASIK]

This report concerns the case of a 28-year-old female patient who was treated with topical steroids for 2 years following complicated hyperopic LASIK surgery with a re-treatment including a re-lift of the flap. A steroid-induced rise in the intraocular pressure (IOP) was subsequently observed on the treated eye, together with a glaucomatous subtotal destruction of the optic nerve, resulting in a residual vision of 1/15. An erroneously low IOP measurement, which was probably the reason for the delay in detecting steroid-induced glaucoma, has been reported in several cases concerning LASIK patients. The reason for the unusually severe course in the case in question can only be presumed, namely a possible accumulation of fluid at the interface or altered biomechanics following hyperopic LASIK surgery. The need for a thorough postoperative examination following refractive surgery must be emphasized. This case shows a cascade of complications following hyperopic LASIK surgery resulting in the functional blindness of one eye.

Interface Fluid Syndrome in Human Eye Bank Corneas after LASIK

PURPOSE

To evaluate the effects of corneal edema on human donor corneas that had previous LASIK using a laboratory model with histologic and ultrastructural correlations.

DESIGN

Experimental study.

PARTICIPANTS

Thirty human eye bank corneas from 15 donors (mean age +/- standard deviation, 49.9+/-8.9 years) who had had previous LASIK surgery (2-8 years before death).

METHODS

The corneas were mounted in an artificial anterior chamber and the corneal endothelium was perfused for up to 5.0 hours with 0.9% saline solution (endothelial cell damage group) or BSS Plus at a pressure of 15 mmHg (control group), or BSS Plus at a pressure of 55 mmHg (high-pressure group). The corneas were evaluated by confocal and specular microscopy before, during, and at the end of the experimental period. Subsequently, the specimens were evaluated by light and electron microscopy.

MAIN OUTCOME MEASURES

Corneal thickness, reflectivity, histology, and ultrastructure.

RESULTS

Endothelial cell damage resulted in an increased (141.5+/-38.8 microm) total corneal thickness relative to controls (52.3+/-33.7 microm), whereas high pressure resulted in a decreased thickness (24.8+/-14.1 microm) relative to controls. This ultimately was due to swelling of the LASIK interface in both groups and swelling of the residual stromal bed (RSB) in the endothelial cell damage group or compression of the RSB and, possibly, the flap in the high-pressure group. A significant increase in corneal reflectivity at the LASIK interface occurred in both groups, primarily due to varying degrees of fluid accumulation and associated hydropic keratocyte degeneration, as well as increased corneal reflectivity in the RSB only in the endothelial cell damage group.

CONCLUSIONS

After LASIK surgery, edematous corneas preferentially hydrate and swell in the paracentral and central interface wound, commonly resulting in a hazy corneal appearance primarily due to keratocyte hydropic degeneration. More severe corneal edema is characterized by the formation of an optically empty space corresponding to an interface fluid pocket. The spectrum of interface fluid syndrome can be described in 3 stages.

Interlamellar flap edema due to steroid-induced ocular hypertension after laser in situ keratomileusis

BACKGROUND

Several recent studies have reported post-laser in situ keratomileusis (LASIK) complications related to a steroid-induced increase in intraocular pressure, including interface fluid and elevated intraocular pressure-induced interlamellar stromal keratitis.

CASES

We examined two cases of interlamellar flap edema due to steroid-induced ocular hypertension after uneventful laser in situ keratomileusis.

OBSERVATIONS

Oral acetazolamide and discontinuance of topical steroids were effective for treating interlamellar stromal edema in both cases.

CONCLUSION

A rise in intraocular pressure should be considered a cause of interlamellar stromal edema after LASIK.

Glaucome cortisonique : étude épidémiologique, clinique et thérapeutique

INTRODUCTION

Cortisone glaucoma is a secondary glaucoma induced by local or oral steroids used to treat chronic inflammatory diseases.

PATIENTS AND METHODS

Retrospective study including 43 eyes of 23 patients (three patients were monophthalmos). We present epidemiological and clinical features with evaluation of functional damage (visual acuity, visual field), and therapeutic results with a follow-up period ranging from 2 to 10 years.

RESULTS

Topical steroids were incriminated in 15 of 23 cases (self-medication), whereas general steroids (for chronic diseases) were used by eight patients. Visual function was seriously affected (visual acuity<1/10 in 23/43 eyes at the first visit with pronounced visual field abnormalities). Surgery was necessary in 16 of 43 eyes (deep sclerectomy with or without implant, trabeculectomy).

DISCUSSION

Cortisone glaucoma is rather frequent in Tunisia where conjunctival allergy and self-medication are common. Young adults are concerned, making it a high surgical risk usually requiring surgical devices such as a T Flux implant.

CONCLUSION

Cortisone glaucoma is a serious complication of steroid therapy that usually affects young adults. The disease is usually detected late, explaining the severe functional damage.

Surgical-glove-related diffuse lamellar keratitis after laser in situ keratomileusis: long-term outcomes

PURPOSE

To study the long-term refractive results in eyes that developed surgical-glove-related diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK).

SETTING

Department of Ophthalmology, Hospital Provincial, Toledo, Spain.

METHODS

This retrospective review analyzed an epidemic of surgical-glove-related DLK over a 5-month period at a single hospital. Twenty-four eyes (24 patients) that developed DLK (DLK group) were compared to 30 eyes (30 consecutive patients) that had surgery during the same time but had an uneventful postoperative course (control group). Follow-up was 12 months in all cases.

RESULTS

Twelve months after LASIK, the mean spherical equivalent was 0.14 diopter (D) +/- 0.36 (SD) in the DLK group and -0.07 +/- 0.33 D in the control group (P=.03). The mean uncorrected visual acuity was 0.91 +/- 0.18 and 0.90 +/- 0.17, respectively (P = .81). The mean best spectacle-corrected visual acuity (BSCVA) was 0.97 +/- 0.08 in the DLK group and 0.99 +/- 0.06 in the control group (P = .42). At 1 year, 91.7% of eyes in the DLK group and 93.3% of eyes in the control group were within +/-0.50 D of the attempted correction (P = .82). The BSCVA was 1.0 or better in 87.5% and 93.3%, respectively (P =.46).

CONCLUSIONS

Early diagnosis and appropriate treatment of glove-related DLK provided visual outcomes that were similar to those in eyes with an uneventful postoperative course. These good results are consistent with those in studies of classic DLK.

In vivo confocal microscopic findings of interlamellar stromal keratopathy induced by elevated intraocular pressure

We report the confocal microscopic findings in a case of interlamellar stromal keratopathy induced by elevated intraocular pressure (IOP) after laser in situ keratomileusis (LASIK). In vivo confocal microscopy showed swollen and enlarged cellular structures and the presence of microlacunae separating the stromal collagen lamellae. Inflammatory mononuclear cells and granulocytes typically seen in patients with diffuse lamellar keratitis (DLK) were absent. Stopping the topical steroids with concurrent lowering of the IOP resulted in improvement in the uncorrected and best corrected visual acuities and was associated with resolution of the corneal findings. In vivo confocal microscopy is a useful tool to study interlamellar stromal keratopathy induced by elevated IOP after LASIK in humans and the response to treatment and to differentiate interlamellar stromal keratopathy from DLK.

In vivo fibreoptic confocal imaging (FOCI) of the human ocular surface

Recent developments in the miniaturization of confocal imaging technology have resulted in the development of a hand-held confocal microscope probe. There are many structures of interest in the human eye that are within reach of a fluorescence-mode confocal microscope; this study assessed the feasibility of in vivo human ocular imaging. Safety analysis was undertaken to ensure that the laser light applied to the ocular surface structures constituted no threat to patient safety. A fibreoptic confocal imaging (FOCI) probe using an illumination wavelength of 488 nm was applied to the ocular surface of four volunteers after topical administration of sodium fluorescein. Stabilization of the probe on the ocular surface was difficult, but movement artefacts could be minimized to a satisfactory level in most subjects by a variety of procedures. High-quality images of conjunctival epithelial and goblet cells, lamina propria structures, accessory lacrimal glands, lacrimal ducts and superficial sclera were obtained. Lateral resolution was 1-1.5 microm and axial resolution was approximately 30 microm; individual erythrocytes could be seen in conjunctival vessels. The rete ridges and intervening epithelial components, including the probable location of corneal limbal stem cells, could be viewed, although it was not possible to distinguish cell subgroups. The study showed that fluorescence-mode imaging of the ocular surface is a viable and promising tool for assessment of diseases and processes involving superficial ocular structures. Refinement of equipment and techniques, particularly probe stabilization, is necessary to realize fully the potential of FOCI for ocular use.

Interface Corneal Edema Secondary to Steroid-induced Elevation of Intraocular Pressure Simulating Diffuse Lamellar Keratitis

PURPOSE

To describe interface corneal edema secondary to steroid-induced elevation of intraocular pressure (IOP) following LASIK.

METHODS

Retrospective observational case series. Diffuse interface edema secondary to steroid-induced elevation of IOP was observed after LASIK simulating diffuse lamellar keratitis (DLK) in 13 eyes. Mean patient age was 31.4 +/- 5.3 years. Patients were divided into two groups according to provisional misdiagnosis: DLK group (group 1) comprised 11 eyes and infection group (group 2) comprised 2 eyes (microbial keratitis). Mean follow-up was 8.1 +/- 0.5 weeks.

RESULTS

In the DLK group, typical diffuse haze was confined to the interface and extended to the visual axis, impairing vision in all eyes. Provisional diagnosis was late-onset DLK and topical steroids were started. Repeat examination showed elevated IOP as measured at the corneal center and periphery using applanation tonometry (mean 19.1 mmHg and 39.5 mmHg, respectively), causing interface edema with evident interface fluid pockets. Steroids were stopped and topical anti-glaucoma therapy was started. The interface edema decreased and at the end of follow-up the corneal transparency was restored and IOP dropped to normal values. The infection group demonstrated a microbial keratitis-like reaction and underwent flap lifting and interface wound debridement and biopsy with administration of fortified antibiotics and steroids. After elevated IOP was detected, steroids and antibiotics were stopped and topical anti-glaucoma therapy was started, resulting in the resolution of the interface edema.

CONCLUSIONS

Interface fluid syndrome secondary to steroid-induced elevation of IOP might develop in steroid responders after LASIK with a misleading clinical picture simulating DLK or infectious keratitis. Management includes stopping topical steroids and starting topical antiglaucoma therapy.

Considerations of Glaucoma in Patients Undergoing Corneal Refractive Surgery

Glaucoma patients present a unique set of challenges to physicians performing corneal refractive surgery. Corneal thickness, which is modified during corneal refractive surgery, plays an important role in monitoring glaucoma patients because of its effect on the measured intraocular pressure. Patients undergo a transient but significant rise in intraocular pressure during the laser-assisted in situ keratomileusis (LASIK) procedure with risk of further optic nerve damage or retinal vein occlusion. Glaucoma patients with filtering blebs are also at risk of damage to the bleb by the suction ring. Steroids, typically used after refractive surgery, can increase intraocular pressure in steroid responders, which is more prevalent among glaucoma patients. Flap interface fluid after LASIK, causing an artificially low pressure reading and masking an elevated pressure has been reported. The refractive surgeon's awareness of these potential complications and challenges will better prepare them for proper management of glaucoma patients who request corneal refractive surgery.

Intraocular pressure measurement in patients with previous LASIK surgery using pressure phosphene tonometer

PURPOSE

To compare intraocular pressure (IOP) assessment in post-LASIK patients using non-contact tonometry, pressure phosphene tonometry and applanation tonometry.

METHODS

Sixty-two consecutive LASIK patients were analysed preoperatively and postoperatively with non-contact, pressure phosphene and applanation tonometry. Comparisons among these values were assessed with paired sample Student t-test, Pearson's correlation test and Bland-Altman plotting.

RESULTS

There was no significant difference for preoperative IOP measurement between non-contact, pressure phosphene and applanation tonometry. The mean +/-SD difference between the preoperative non-contact tonometry and postoperative pressure phosphene tonometry IOP measurements was 0.80 +/- 2.77 mmHg (P < 0.01). Postoperative applanation tonometry significantly underestimated IOP measurement by 5.45 +/- 2.96 mmHg (P < 0.001) and postoperative non-contact tonometry significantly underestimated IOP measurement by 9.96 +/- 2.25 mmHg (P < 0.001).

CONCLUSION

Pressure phosphene tonometry may provide an alternative method for the assessment of IOP in post-LASIK patients.