Interface Fluid After Laser in situ Keratomileusis

Interface fluid syndrome after LASIK surgery: retrospective pooled analysis and systematic review

Interface fluid syndrome (IFS) is a complication associated with laser in situ keratomileusis (LASIK) surgery where a fluid pocket in the corneal stroma decreases visual acuity. A systematic review of IFS cases using PRISMA guidelines was performed yielding a total of 33 patients. 2 outcomes were selected for logistic regression analysis: final corrected distance visual acuity (CDVA) and need for surgical management. Results showed 33.3% of patients required surgery, 51.5% had their IFS resolve within 1 month or sooner, and 51.5% had final CDVA 20/25 or better. Higher presenting intraocular pressure (IOP) and duration of IFS ≤1 month was associated with higher odds of final CDVA 20/25 or better (adjusted odds ratio [aOR] 1.12, P = .04; aOR 7.71, P = .02, respectively). Endothelial cell dysfunction led to 17.55 greater odds for requiring surgical compared to medical management (aOR 0.36, P = .04). Presenting IOP and duration of IFS predicted final CDVA, while prior endothelial cell dysfunction predicted need for surgery.

Interface Fluid Syndrome Masquerading as Diffuse Lamellar Keratitis After Small Incision Lenticule Extraction

A 34-year-old male with no past medical or ocular history underwent bilateral uncomplicated small incision lenticule extraction (SMILE). On day 1, uncorrected distance visual acuity (UDVA) was 20/25 in the right eye (OD) and 20/20 in the left eye (OS). The intraocular pressure (IOP) was 12 mmHg in both eyes (OU). On day 17, UDVA was 20/70 OD and 20/30+2 OS. Slit-lamp examination (SLE) revealed diffuse 2+ haze at the interface suspicious for diffuse lamellar keratitis (DLK). Topical difluprednate was added twice a day (BID). Vision decreased by day 20 with a significant myopic shift and 3+ interface haze OU. A washout of the interface was performed. Topical steroids were increased with oral prednisone. One day after the washout, vision and interface haze improved. On day 3 status post washout, UDVA decreased to 20/70 OD and 20/50 OS. IOP was 42 mmHg OU. A diagnosis of interface fluid syndrome (IFS) was confirmed. All steroids were stopped while adding ocular hypotensive medication. One month later, visual acuity was 20/20 OU with a complete resolution of interface haze. Only a handful of IFS has been documented in SMILE, an incidence that may increase as SMILE becomes more common. Among all SMILE cases, IFS was most commonly associated with steroid-induced ocular hypertension and a myopic shift around 21 days postoperatively. A fluid cleft at the interface may not always be visible with SLE, masquerading as DLK. Scheimpflug densitometry and anterior segment optical coherence tomography (AS-OCT) may aid in quantifying interface edema needed to confirm a diagnosis when IOP is unclear. A corneal washout can immediately improve corneal edema, but the preferred treatment is discontinuing all steroid medication and starting glaucoma drops.

Pharmacologic Management of Pressure-Induced Stromal Keratopathy after LASIK

PURPOSE

To emphasize the importance of anticipation of pressure-induced stromal keratopathy (PISK) in eyes with a previous history of LASIK.

CASE REPORT

A 40-year-old man developed LASIK-related pressure-induced stromal keratopathy after uneventful phacoemulsification (Phaco) and intraocular lens (IOL) implantation in his left eye. With immediate discontinuation of the steroid drops and initiation of antiglaucoma medication, his visual acuity, interface edema, and haze improved rapidly. One year later, during Phaco with IOL implantation in his other eye, with anticipation of a similar LASIK-related pressure-induced stromal keratopathy, a very brief course of soft steroid therapy was given together with antiglaucoma medication. Intraocular pressure elevation was avoided, and no interface edema or haze was observed.

CONCLUSIONS

This case illustrates that the risk for LASIK-related pressure-induced stromal keratopathy may be reduced with appropriate precautions.

The Effect of Corneal Refractive Surgery on Glaucoma

Laser-assisted refractive procedures have become very popular in the last two decades. As a result, a "generation" of patients with altered corneal properties is emerging. These patients will require both cataract extraction and glaucoma follow-up in the future. Since the glaucoma examination largely depends on the corneal properties, the reshaped postrefractive surgery cornea poses a challenge in the diagnosis, follow-up, and management of the glaucomatous patient. In order to overcome this problem, every patient who is planned to undergo corneal refractive surgery must have a thorough glaucoma examination in order for the ophthalmologist to be able to monitor their patients for possible glaucoma development and/or progression. Some examinations such as tonometry are largely affected by the corneal properties, while others such as the evaluation of the structures of the posterior pole remain unaffected. However, the new imaging modalities of the anterior segment in combination with the most recent advances in tonometry can accurately assess the risk for glaucoma and the need for treatment.

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 after bioptics

PURPOSE

To report an unusual case of interface fluid syndrome after refractive surgery.

METHODS

A 37-year-old man with high myopia underwent a planned bioptics procedure including creation of a corneal flap using a mechanical microkeratome and concurrent anterior chamber phakic intraocular lens implantation; excimer laser ablation was not performed at this time.

RESULTS

Postoperatively, the patient developed corneal edema and was referred to our department. Interface fluid syndrome was confirmed using optical coherence tomography; the mechanism was due to endothelial cell pump dysfunction.

CONCLUSIONS

This is the first report to document interface fluid syndrome following a planned bioptics procedure.

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.

Presumed stromal graft rejection after automated lamellar therapeutic keratoplasty: case report

Purpose

To describe the development of presumed immune-mediated stromal rejection after automated lamellar therapeutic keratoplasty (ALTK) and its reversal after initiation of intensive topical corticosteroid therapy.

Methods

Observational case report.

Results

Stromal edema localized in the graft developed 42 days after ALTK for Avellino corneal dystrophy in a 65-year-old man. After one week of intensive topical corticosteroids, complete reversal of graft edema occurred, with full recovery of visual function.

Conclusion

The clinical appearance and response to therapy in this case supported the diagnosis of immune-mediated stromal rejection. Ophthalmologists should be aware that stromal rejection may occur in lamellar corneal grafts.

Interface fluid syndrome in laser in situ keratomileusis after complicated trabeculectomy

A 69-year-old man developed stromal edema and a pocket of fluid in the laser in situ keratomileusis (LASIK) interface wound in the left eye after acute endothelial cell loss from complicated trabeculectomy. He eventually required penetrating keratoplasty along with cataract surgery. Histologic examination of the corneal button showed an edematous 720 microm central residual stromal bed, a 54 microm empty space at the level of the central interface wound, and a 154 microm LASIK flap. The endothelial cell count was 0 to 2 cells per high-power field, corresponding to a cell density of 450 to 500 cells/mm(2). Four years after LASIK, the central interface wound was susceptible to forming a pocket of serous fluid after the corneal endothelial function was compromised.

Lamellar interface fluid accumulation following traumatic corneal perforation and laser in situ keratomileusis

A 41-year-old man with myopic astigmatism had laser in situ keratomileusis (LASIK) in each eye in April 2002. Ten months later, he sustained a central perforating corneal injury to the right eye. One day following repair of the corneal wound, he presented with diffuse corneal epithelial microcystic edema, lamellar interface fluid accumulation, and 20/400 visual acuity. Additional sutures were placed to close a presumed posterior wound gape with complete resolution of the corneal edema and lamellar interface fluid collection. One year later, his best corrected visual acuity measured 20/20+ in the right eye. This case is the first to document lamellar interface fluid accumulation following LASIK owing to traumatic disruption of the corneal endothelium.

Late-onset idiopathic diffuse lamellar keratitis after laser in situ keratomileusis

We report a case of late-onset diffuse lamellar keratitis (DLK) in the left eye of a 56-year-old white woman 3 years after uneventful bilateral laser in situ keratomileusis (LASIK). Slitlamp examination revealed stage 3 DLK with diffuse, multifocal, dot-like, and granular haze in the interface. The DLK did not have an obvious causative agent such as trauma or epithelial defects and responded rapidly to topical corticosteroid therapy. Surgery was performed to relift the flap, remove cellular infiltrates, and obtain cultures. The microbiology culture was negative. This case indicates that DLK can occur several years after LASIK without an obvious cause.

Photoablative inlay laser in situ keratomileusis (PAI-LASIK) in the rabbit model

PURPOSE

To evaluate the suitability, biocompatibility, and efficacy of a proprietary hydrogel photoablative inlay (PAI) for use during laser in situ keratomileusis (LASIK).

SETTING

Laboratory study, Tulane University Health Sciences Center, New Orleans, Louisiana, USA.

METHODS

Eight rabbits (1 eye each) underwent the PAI-LASIK procedure; 4 eyes had a disk-shaped inlay and 4, a donut-shaped inlay. Preoperatively, the hydrogel material was ablated with a programmed correction of 5.0 diopters of hyperopia or myopia.

RESULTS

The eyes were followed for 1 to 16 months. No eye showed signs of rejection or extrusion of the PAI. There was no significant difference in corneal clarity or the healing rate between eyes with donut-shaped PAIs and those with disk-shaped PAIs. One eye with a donut-shaped PAI had minimal corneal haze. The remaining inlays did not opacify or fracture during ablation.

CONCLUSION

The hydrogel material can be used for the proposed PAI-LASIK procedure.