LASIK Complication A. Al-Muammar

LASIK Complication Intraoperative  Poor exposure ► Deep orbit, small eye, narrow palpebral fissure, drape, and lid speculum  Difficulty in placing suction ring  Lid injury  Poor centration during laser ablation  Water pooling ► Lateral canthotomy, facial nerve block, retrobulbar block, converting to PRK, or abandoning surgery

LASIK Complication Intraoperative  Inadequate suction ► Good suction ( IOP > 75 mmHg) would provide depth control during microkeratome pass ► Poor or broken suction can result in thin, buttonholes, or free cap ► Inadequate suction can be due to suction ports clogging by debris, drape, speculum, chemotic or redundant conjunctiva, or defect in suction line

LASIK Complication Intraoperative  Flap complication ► Thin flap  The incidence of thin flap reported to vary between 0.3% and 0.75%  Flap considered to be thin when keratome cuts within or above Bowman’s layer  Recognized by shinny reflex on the stromal surface  It tends to occur with flat cornea or poor suction  Reposition the flap and abort the procedure  Deeper flap (20-60 micrm) maybe recut weeks

LASIK Complication Intraoperative ► Buttonholes flap  A buttonholed flap occurs when microkeratome blade travels more superficially than intended and enters the epithelium/Bowman’s complex  Buttonholes maybe partial thickness if they transect Bowman’s layer or full thickness if they exit through the epithelium.  The incidence of buttonholes ranges between 0.2% and 0.56%  Buttonholes flap tend to occurs in case of steep cornea >48 D, resistance to cutting, or lack of synchronization between keratome movement and oscillatory blade movement

LASIK Complication Intraoperative ► Tx  Reposition the flap  And wait 3 to 6 months before recutting  Transepithelial PRK within 2 weeks

LASIK Complication Intraoperative  Irregular flap ► Abnormal shape/diameter/ or thickness flap ► Result from damaged microkeratome blades, irregular oscillation speed, or poor suction ► Incidence 0.09%-0.2% ► Reposition the flap and abort the procedure

LASIK Complication Intraoperative ► Incomplete flap  Created when the microkeratome blade comes to halt prior to reaching the intended location of the hinge  Incidence ranges between 0.3% and 1.2%  Microkeratome jamming due to either electrical failure or mechanical obstacles as lashes, drape, or loose epithelium  Unless enough space exists for ablation( 1mm space between ablation and the edge), incomplete flap are best managed by immediate repositioning and postponing the procedure

LASIK Complication Intraoperative ► Free flap  Unintended free flap can occur with corneas flatter than 38D prior to surgery, poor suction, or migration of suction ring.  Recent studies report an incidence between 0.01% and 1%  If the flap is not visible on the surface of the cornea, then the flap could be inside the microkeratome head  Marking the cornea prior to surgery is very important for proper placement of free flap  If the cap has normal thickness and diameter, the ablation can still be performed. Flap repositioned using placed marks. A BCL applied to tamponade the cap. Suturing rarely necessary  Abnormal thin/irregular flap which is the usual case should be repositioned using sutures, and laser should be delayed  Early removal of sutures is important to minimize scarring  If the flap cant be retrieved, epithelium is allowed to heal as in PRK

LASIK Complication Intraoperative ► Decentered flap  Flap decenterations are attributable to an inexperienced surgeon improperly aligning the suction ring with the limbus or migration of the ring on the corneal surface when suction applied  Most surgeon will not proceed with laser unless the ablation can be placed 1 mm of the bed is left between the ablation peripheral bed and the flap margin  The Introduction of microkeratome with large diameter flap have reduced this problem

LASIK Complication Intraoperative ► Corneal perforation and anterior segment damage  Result from error in placing the plate that control the depth of the cut into instruments  Newer designs have eliminated the potential for these severe complications since they have a fixed depth plate and components of the microkeratome cannot be inserted incorrectly.

LASIK Complication Intraoperative ► Intraoperative bleeding  Corneal neovascularization from pannus, decentered flap, and large flap are the most common causes of intraoperative bleeding  Topical vasoconstrictors can be applied 3 to 5 minutes prior to surgery in high risk group  Tamponade any bleeding prior to flap lifting  Any blood that might interfere with laser should be irrigated

LASIK Complication postoperative ► Epithelial complication  Incidence reported to be around 5%  Epithelial defects more common in patients with abnormal epithelial adhesion as in EBMD, or patient with who develop epithelial defect in the first eye  Mild staining at the edge of the flap is common  Large defects are worrisome especially those with connection to the flap edge  Epithelial defect can increase the risk of infection, epithelial ingrowth, and DLK  Treated with BCL, or patch

LASIK Complication postoperative ► Pain  Most patients experience only mild discomfort following LASIK  Severe pain may herald more severe complication such as a displaced flap, DLK, or infection

LASIK Complication postoperative ► Flap striae and wrinkles  Reported incidence between 0.2% and 1.5%  It is related to the disparity between the curvature of the posterior surface of the flap and the bed following complication  Large thin flap, improper BCL placement, removal of lid speculum, and eye rubbing can increase the risk of striae  Striae can be micro or macro. Retroillumination and fluorescein can help in detecting striae  Visually significant striae should be treated as soon as possible to avoid fixed striae  LASIK flap iron, lifting the flap =/- suture, and PTK are possible options to treat striae

LASIK Complication postoperative ► Displaced flap  Emergency, should be repositioned as soon as possible to prevent infection, fixed folds, and epithelial ingrowth  Incidence have been reported to be 1.1% and 2% (old reports)  Usually occur in the first 24 hrs after surgery  Eye lid rubbing, squeezing, and trauma especially with large thin flap are the main predisposing factor for displaced flap  Flap should be reflected, examined for epithelial cells or debris which should be scraped, the reposition the flap and apply BCL

LASIK Complication postoperative ► Epithelial ingrowth  Reported incidence vary between 1% and 2%  Possible mechanisms ► Mechanical dragging by keratome blade during keratectomy ► Backflow during irrigation carrying floating epithelial cells ► Ingrowth at the junction of the epithelium and keratotomy ► Implantation with instruments ► Cell migration through epithelial defect

LASIK Complication postoperative  Complications ► Decrease visual acuity ► Anterior stromal melt  Treatment ► Flap lifting ► Irrigation ► Scraping ► Alcohol ► PTK ► MMC ► suture

LASIK Complication postoperative ► lamellar interface debris ► Oil ► Mucous ► Particles from the sponge ► Metallic fragments from the Blade ► RBC ► Powder from gloves ► Lint fibres ► Lashes  Peripheral debris which not associated with keratitis or neovascularization can be left undisturbed  Central debris should be removed

LASIK Complication postoperative ► Diffuse Lamellar Keratitis (DLK)  Diffuse non-infectious inflammation at the level of the interface during the first few days after LASIK  Reported incidence is highly variable, between 0.2% and 3.2%  Possible causes, most of these are based on speculation without supporting data ► Betadine ► Impure BSS ► Retained meibomian secretions ► Metallic debris ► Talc from gloves ► Thermal effect from the laser ► Lubricants on the microkeratome or blades ► Topical medications such as anesthetics ► Bacterial cell wall components (lipopolysaccharides) ► Endotoxins ► IL 1 released from corneal epithelial cells following cell injury or death

LASIK Complication postoperative  Stages ► Stage I seen on day 1 as white, granular cells in the periphery with sparing of the visual axis. ► Stage II seen on day 2 or 3, shows white cells in the visual axis ► Stage III involves an aggregation of cells clumped in the visual axis and associated with haze and reduce vision ► Stage IV involves central stromal necrosis, melt, and secondary hyperopia with irregular astigmatism

LASIK Complication postoperative ► Tx  Stage I and II, should be treated with intense topical steroid every 1 hr  If inflammation progressed even with steroid or patient presented with stage III or IV ► the flap should be lifted ► Cleaning ► profuse irrigation ► Culture for bacteria and fungus ► Topical steroid =/- oral steroid ► PTK/HCL

LASIK Complication postoperative ► Infection  Infectious agents that have been reported after LASIK include ► Virus ► Bacteria (including atypical mycobacterium and nocardia) ► Fungus ► Parasite  If infiltrate noted, it should be treated as infectious until proven otherwise  Infiltrate should be cultured …bacteria, fungus, acanthameoba, Ziehle-Nelson stain  Tx ► Abx ► Antifungal ► Antiviral ► Flap removal

LASIK Complication postoperative ► Dry eye  Neurotrophic in origin  Worse in patient who are known to have dry eye  Present with PEE and visual fluctuation  May last 6 to 8 months  Tx ► Tears ► Punctum plug

LASIK Complication postoperative ► Corneal ectasia  Iatrogenic keratoconus like condition  Minimum stromal bed thickness of microm should be left after laser ablation  Present as progressive myopia, or decrease visual acuity secondary to irregular astigmatism  Dx ► Orbscan ► Pachymetry  Tx ► RCL ► Corneal ring ► PKP

LASIK Complication psotoperative  Decentration  Irregular astigmatism  Glare, and haloes  Overcorrection  Undercorrection