Currently, LASIK is the most popular refractive surgery. Here I discussed about the procedure & common complications of this surgery.

1. Dr. Ashraful Huq
FCPS
ashraf.huq.bd@gmail.com
Eye Specialist & Surgeon
Bangladesh Eye Hospital Ltd.

2.  Most commonly performed refractive surgery
 Excimer laser ablation of corneal stroma
beneath a hinged corneal flap
 Used to correct-
Myopia: 12 D
Hypermetropia: 4 D
Astigmatism: 5 D

3.  Barraquer: Lamellar refractive surgery in 1949
 Ruiz & Rowsey: in situ keratomileusis in 1980
 Ruiz: Automated microkeratome in 1980
 Pallikaris: LASIK in 1990

4.  Normal cornea – prolate shape ( greater curvature
centrally )
 Myopic correction – create an oblate shape by
central corneal laser ablation
 Hypermetropia- Excimer laser ablation at mid-
periphery steepening of central cornea

5.  Mixed astigmatism –
1)Bitoric LASIK technique – flattening the steep
meridian with paracentral ablation over the flat meridian
2)Cross-cylinder technique – dividing cylinder power
into 2 symmetrical parts – half of the correction is treated
on the positive meridian & half on the negative meridian

6.  Age above 18 years
 Refractive status should be stable for at least 1 year
 Patients need to be fully informed about potential risks,
benefits and realistic expectations

7.  Patient expectation
 Presbyopia
 Complications
 Alternate options
 Informed written consent

8.  Corneal Thickness >450
Since residual base-250µm
Flap- 120µm (90-160)
 Contact lens free period before examination :Contact lens free period before examination :
2-3 wks for rigid contact lens2-3 wks for rigid contact lens
3 days to 1 wk for soft contact lens3 days to 1 wk for soft contact lens

9.  Unhealthy cornea
 Active, recurrent or residual eye disease
 Severe dry eye
 Large pupil size
 One eyed
 Non- cooperative person

10.  Social History -
 Ocular History-
Refractive history
Ocular pathology
Ocular surgery
 Medical History-
DM
RA
Collagen vascular disease
Pregnancy
Drugs-Steroid, Amiodarone

11.  Visual acuity- UCVA & BCVA (retino+auto+cyclo)
 Pupillometry
 Slit lamp examination
 IOP
 Schirmer Test, Tear film break up time
 Fundoscopy

12.  Pachymetry
 Corneal Topography
 Keratometry

13.  Excimer laser machine – for ablation
 Microkeratomes – creating flap
 Femto laser - flap

14.  Verification of entered computer data before starting
procedure
 Patient on operating table
 Topical anaesthesia
 Surgical Painting and draping
 Lid speculum
 Proper centration over pupil & maintenance by the aid of
Tracking systems & iris registration
 Other eye taped shut to prevent cross-fixation & drying

15.  Corneal marking with ink
 Adequate placement of suction ring using bimanual/ one
hand technique
 Suction engagement by foot control
 Adequate IOP (>65mmHg)

16.  Steel Microkeratome
-Uses Disposable blades
-Blade Plate can be set at 120µ,140µ,160µ and180µ
-Nasal or superiorly hinge flaps can be created
(↓ corneal denervation)
 Laser Keratome (IntraLase)
- high precision
- Uses brief Femtosecond laser pulses to cause
disruption in a lamellar plane
- Needs lower vacuum & any hinge can be made
- Can make flaps as thin as 90µ
[↑speed - ↓time - ↓error - ↑safety ]

17. After flap is lifted, assessment of residual corneal bed
thickness done
 Laser applied to the stroma according to the ablation
profile calculated by the machine.
Excimer Laser beam is delivered

18. After irrigating interface ,flap repositioned
Sweeping movements with a wet cellulose sponge
From the hinge towards the periphery of flap
Adhesion verified
Topical antibiotic, steroid & lubricant instillation
BCL
Slit lamp examination after 1 hour

19.  Medication-
Antibiotic & Steroid combination-3 wks
Preservative free artificial tear-6 mnths
 Instructions-
Not to rub eyes
Avoid driving 1 week
Avoid swimming 1 month
Avoid cosmetics 1 month

20.  1 day after surgery
 7 days after surgery
 6 weeks after surgery
 3 months after surgery
 6 months after surgery
 12 months after surgery

21.  INTRAOPERATIVE COMPLICATIONS
 POST OPERATIVE COMPLICATIONS

22.  Incomplete or irregular flap
– premature termination of microkeratome advancement
- inadequate globe exposure
- loss of suction during pass
- surgery should be postponed
 Thin flap
- due to poor suction
- difficult to reposition & likely to wrinkle
-surgery may need to be postponed Fig: Incomplete Flap
[not for experts]
 Buttonholed flap
-surgery should be postponed,
flap repositioned
[steep cornea]
Fig: Button hole

23.  Free Flap
-Operation done, flap repositioned
 Corneal Perforation
-BCL or suturing
[very rare] Fig: Free flap
 Inter face Debris
- Irrigation by BSS
 Fig: Interface debris Fig: Iris damage after corneal perforation


24.  Decentration
– current lasers incorporated with eye-tracking &
iris registration systems
- retreatment
 Under/ Over-correction
- excessive hydration : under correction
- desiccation : overcorrection & haze
- retreatment

25.  Flap wrinkling or displacement
– first 24 hrs
- lifted & repositioned
(stria)
 Night vision disturbances
– haloes / glare
(sub epithelial haze) Fig: Wrinkling
 Dry eye- [corneal denervation]
-Fluctuating vision, SPK
-Temporary neuropathic cornea
-Rx-Preservative Free lubricants
Fig: Inferior displacement
Fig: SPK
Fig: Subepithelial haze

26.  Diffuse lamellar keratitis (Sands of
Sahara)
- non-infective interface inflammation
- 1_
7 days after LASIK / 24 hrs
- fine granular sand-like infiltrate at interface
- Rx topical steroids and antibiotics
- if not treated corneal scarring
- Rx- Surgical removal of epithelium
 Infectious keratitis
 Lost flap post-operatively
Fig: Diffuse lamellar keratitis

27.  Epithelial defects ingrowth
-Presents 1-3 months after LASIK.
-Cause-Epithelial cells trapped under flap
Fig: Epithelial defect
Fig: Epithelial ingrowth

28.  EctasiaEctasia
- Risk Factors- Risk Factors
Ablation beyond 250 µmAblation beyond 250 µm
Forme fruste´ keratoconusForme fruste´ keratoconus
- Rx – CCL, Intra-stromal inlays, Corneal grafting- Rx – CCL, Intra-stromal inlays, Corneal grafting
Fig: Post LASIK ectasia

29.  Inaccurate measurement of IOP
 Inaccurate IOL power calculation
 Difficulty in contact lens fitting