Ocular Surface Syndrome after LASIK

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1 Alaa Atef Ghaith, MD Professor of Ophthalmology Alexandria University Ocular Surface Syndrome after LASIK Up to 33% of eyes Multifactorial entity which causes distress to the patients and physicians 1

2 Ocular Surface Syndrome after LASIK Pathogenesis Flap creation cutting the subepithelial nerve plexus cutting the reflex arc stimulating lacrimation neurotrophic epitheliopathy. Ocular Surface Syndrome after LASIK Contact Lens Wear Dry Eye Contact lens intolerance patients seek laser vision correction worsening of dry eye 2

3 Ocular Surface Syndrome after LASIK Pathogenesis The position of the hinge: The superior hinge doubles the amount of diminished sensation and lead to more dryness than the nasal hinge due to cutting of both sets of long corneal nerves which are at 3 and 9 o clock oclock. Corneal diminished sensation and dryness are 50% less with nasal hinge (Bucci 2003) Ocular Surface Syndrome after LASIK Pathogenesis Touch ups increase the incidence of dryness and its severity by about 30% due to more trauma to the corneal surface and corneal nerves. 3

4 Ocular Surface Syndrome after LASIK Pathogenesis REGRESSION is more in dry eye state: 27% in dry eye patient and only 7% in non dry eyes. Use of tear substitute can correct a large amount of regression or even prevent it. Mechanism of Regression 1. Epithelial hyperplasia: due to increase epidermal growth factor 2. Stromal remodeling due to apoptosis of stromal cells due to release of cytokines from lack of innervation. 4

5 Risk of chronic dry eye after LASIK increase with: 1. Sex (more in females) 2. Higher degrees of error 3. Greater depth of ablation 4. Contact lens wearing (causes dry eyes and corneal thinning). 5. Touch ups Prevention of OSS after LASIK Proper history of dry eye complains and history of CL wear and intolerance. Examination of dry eye state in every case. BUT, schirmer test and LIPCOF SIGN. Stop medications which cause dry eye as antihistaminic, contraceptive pills, sleeping pills and diuretics. 5

6 Lipcof stage 0 Lipcof stage 1 6

7 Lipcof stage 2 Lipcof stage 3 7

8 Lipcof stage 4 Prevention of OSS after LASIK If severe dry eye is present, alternative refractive options should be considered. If patient has mild dry eye, artificial tear substitutes should be given for at least one week pre-op. If he is wearing a contact lens, this should be discontinued for at least two weeks and tears substitutes given. 8

9 Prevention of OSS after LASIK Reassessment is done after two weeks and if no improvement consider plugs and/ or cyclosporine drops. Intra operatively shift to nasal flap use artificial tears freely, minimal amount of anesthetic drops intra operatively lacrimal plugs and artificial tears at the end of the operation. 9

10 Ocular Surface Complications of LASIK Epithelial Defects Risk Factors Epithelial basement membrane dystrophy Older age Precautions 1. Limitation of toxic topical medications 2. Keep eyes closed after topical anesthetic 3. Use of lubricating drops during flap creation 4. Meticulous microkeratome maintenance 5. Shutting off suction on the microkeratome reverse pass Ocular SurfaceComplications of LASIK Epithelial Defects Management 1. BCL at the end of procedure (retained until complete stable re-epithelialization) 2. Frequent eye lubricants (or even punctal occlusion) 3. Debridement or even PTK 10

11 Ocular Surface Complications of LASIK Striae (Flap Folds) Risk Factors 1. Thin flaps 2. Deep ablations with flap-bed mismatch 3. Excessive irrigation under the flap Importance The success rate of treating visually-significant folds falls dramatically with time. Complications of LASIK Postoperative Complications Striae (Flap Folds) Types Microstriae Macrostriae 11

12 Macrostriae Microstriae Pathology Large folds, entire flap thickness Fine folds, Bowman s layer Cause Slit-lamplamp Direct illum. Flap slippage Broad parallel undulations ± widened flap gutter Flap-bed mismatch; contracture of flap Fine folds, gutter usually symmetric Retroillum. Same as above Folds more obvious Fluorescein Same as above Folds more obvious Analogy Wrinkles in skewed carpet Dried cracked mud Vision Markedly decreased BCVA Subtle decreased BCVA or asymptomatic Topography Marked disruption over striae Normal or slight disruption Treatment Acute Refloat/reposition flap immediately Observe; aggressive lubrication Established (> 24 hours) Refloat, de-epithelialize epithelialize over striae, hydrate and stroke PTK hif visually significant, refloat; try hydration, stroking, suture PTK 12