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Cataract and Refractive > Keys > Flashcards

Keys Flashcards

1
Q

What are the causes for iridescent lens particles?

A

Myotonic dystrophy (DMPK; ZNF9); hypocalcaemia; hypothyroidism; drugs; familial; idiopathic;

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2
Q

What are the causes for lenticonus?

A

ANTERIOR: Alport syndrome (XL: hereditary nephritis + embryotoxon; deafness, RP, peripheral fleck; perimacular dot-flecks; ant-subcapsular cataract)
POSTERIOR: PHPV, idiopathic

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3
Q

What systemic diseases can cause congenital cataract?

A

(1) Alport – haematuria, nephritis, posterior embyrotoxon, ant. lenticonus * urine amino acid quantification
(2) Down’s Syndrome
(3) Galactisemia – galactokinase deficiency causes mental retardation+cirrhosis+ oil droplet cataract *reducing substances in urine;
(4) TORCH - Rubella – pearly white star fish nuclear cat, S&P chorioretinitis, microphthalmos, keratitis, iris hypoplasia, Glc, deafness, heart abnormalities
(5) Lowe syndrome – XL: oculocerebrorenal syn – cong glaucoma, mental retardation, XL, haematuria
(6) Parathyroid – Ca++, PO4
(7) Hyperferritinaemia - cataract syndrome gout is cunt which causes cataract
(8) Drugs: corticosteroids; chlorpromazine; chloroquine; anti-cholineresterases (physostigmine); allopurinol

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4
Q

List conditions which confer high risk cataract surgery.

A

1) Phacodonesis
2) Previous PEI
3) Phacomorphic glaucoma (inflamed eye)
4) Poor health
5) PMHx
6) Previous ocular surgery + other factors

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5
Q

List reasons for difficulty in performing biometry

A
  • Poor tear film
  • Uncooperative patient
  • Previous cornea graft / scar
  • Ptosis
  • Strabismus
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6
Q

What is the original SRK (Saunders, Retzlaff, Kraff) formula for emmetropia?

A

P = A – 2.5L – 0.9K
Where P = IOL power required, A = IOL specific A constant, L = Axial length (mm), K = average corneal refractive power (D)

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7
Q

What is the SRK II formula?

A

P = A1 – 0.9K – 2.5L

Same as SRK, but the A constant modified depending on axial length

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8
Q

In which situations would you use the various 3rd generation IOL calculation formula? (ie. excluding 4th generation)

A

Hoffer Q: Best for short AL < 22mm
Holladay I: Best for average AL 24 - 26 mm
SRK/T: Best for long AL > 26 mm

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9
Q

What is the limitation of 3rd generation IOL calculation formulas? What complication may arise from this inaccuracy?

A

(1) Does not account for effective lens position. Uses assumption that ACD is proportional to AL.
(2) Refractive surprise in post-refractive patients

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10
Q

What are the 4th generation IOL calculation formulas and how does it differ from the 3rd generation?

A

(1) Haigis:
- Requires real, not assumed measure of ACD
- Has 3 adjustable A constants (a0, a1, a2)
- Requires surgeon optimisation of 200 patients
(2) Holladay II
- Requires 7 different variables to be measured
(white to white, corneal diameter, ACD, lens thickness, patient’s age, preop Rx and axial length)
- Highly accurate for wide variety of patients

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11
Q

Of all the IOL power calculations, which is best for the following biometery?

A

AL < 22: Hoffer Q
AL 22 - 24.5: Hoffer Q, Holladay I, SRK/T
AL 24.5 - 26: Holladay I
AL > 26: Haigis or Holladay II

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12
Q

What are the effects for different sources of error in IOL calculation?

A
  • Axial length 1mm = 2.5-3D

* IOL position 1mm = 1.00D

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13
Q

What change do you make when moving an in-the-bag SA60AT to a sulcus MA60AC?

A 
For most patients, would subtract 1.0D, but technically based on IOL power:
\+5    	to  	+7	No change
\+7.5   	to 	+16	Subtract 0.5D
\+16.5 	to 	+27	Subtract 1.0D
\+27.5	to 	+30	Subtract 1.5D
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14
Q

How do you treat corneal astigmatism during cataract surgery?

A

• 1.5 D
Toric intraocular lens implantation (SN60T3=1D; T4=1.5D; T5=2D @ corneal plane; Rayner 1-11D)
- 95% of toric patients achieved >6/12 UCVA vs 80% of spherical control, ~3% will have axis misalignment >10o

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15
Q

When converting from PCIOL to ACIOL what do you do?

A

(1) Add 1mm to the white-to-white D; lenses typically come in 12.5; 13.0; 13.5
(2) Subtract 3D from lens power as A constant different (115 vs 118)

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16
Q

What are the steps in checking the phaco machine?

A

1) Is probe connected?
2) Irrigation working?
3) Does the probe tune correctly?
4) Does BSS reflux?

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17
Q

How do you adjust AL measurements when silicone oil is in the eye?

A

(1) Using A-scan with the velocity conversion equation (silicon oil slows waves to 980-1040m/sec)
(2) Change IOL-Master settings (under AL settings)

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18
Q

When would an IOL-Master be unable to take a reading?

A
  • dense NS cataract
  • dense PSCC
  • vitreous H’ge
  • central corneal scar
  • Poor patient cooperation?
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19
Q

What are the corneal changes in laser vision correction?

A

MYOPE:
- Flattens cornea & ↑ spherical aberrations
- ∴ use aspheric IOL (Technis/SNWF)
HYPEROPE:
- Steepens cornea & ↓ spherical aberrations
- ∴ use spheric (SN60)

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20
Q

What are the Methods of Determining Corneal Power After Keratorefractive Surgery?

A

(1) Pre-refractive K’s known
• Clinical history method (aka calculation method)
(2) Pre-refractive K’s unknown and VA > 6/24
• Trial hard contact lens method
(3) Pre-refractive K’s unknown VA < 6/24
• Videokeratography (central power at multiple paracentral points)
(4) Additional
• Ideally perform all methods on ASCRS website (www.ascrs.org)
• Use highest value from more than one 3rd generation IOL formula (Haigis-L; Holladay1; SRK/T)
• Ensure pt has realistic expectations
• Don’t use multifocal IOLs (will degrade contrast further)
• No lens issues if only had astigmatic correction

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21
Q

What are the considerations for monovision?

A
  1. Distance for dominant eye;
  2. Non-Dominant most myopic that they can handle for distance
  3. Majority of time will be glasses free – will need glasses for extremes
  4. Contact lens trial for 1-2/52
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22
Q

What are the contraindications for inserting multifocals?

A
  • Inability to insert bilaterall (Generally require bilateral insertion)
  • Astigmatism
  • Retinal disease
  • Patient expectations
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23
Q

What are the risks of multifocal IOL?

A
  1. Decreased contrast sensitivity
  2. Halos/glare – esp at night
  3. Poor vision if develop AMD or if small pupil (<2.5mm)
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24
Q

Describe the different types of viscoeleastic.

A
  • Cohesive - easy to remove; reduced corneal coating (eg. Healon; Healon GV; Provisc)
  • Dispersive - corneal protection; difficult to remove (eg. Viscoat; Ocucoat)
  • Viscoadapative - very stable; very difficult to remove (eg. Healon 5)
  • Viscodispersive - good for FED+Glc; expensive (eg. discovisco)
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25
Q

What are the stages of foot pedal?

A

0 – everything off
1 – irrigation
2 – irrigation + aspiration
3 – irrigation + aspiration + phaco

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26
Q

What determines the vacuum to build to vacuum limit in peristaltic machine?

A

The Aspiration Flow Rate

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27
Q

Compare the two mechanisms of phaco machine pumps.

A

(1) PERISTALTIC
• Flow based (adjusts flow and vacuum)
• Flow is constant until occlusion
• Pros - Better for sculpting, no need for compressed air, direct followabilty control
• Cons - Post occlusion surge, need occlusion for vacuum to build
• Machine (eg. infinity)
(2) VENTURI
• Vacuum based (vacuum always on)
• Flow varies with vacuum
• Pros - Less posterior occlusion surge, better for vitreous removal, material comes to tip easily
• Cons - Need source of compressed gas, need rigid cassette, indirect followability
• Machine (eg. Stellaris, Accurus)

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28
Q

What are the phacodynamic principals for each phaco step?

A

(1) Sculpt – non-occlusive: low aspiration flow rate = less turbulence
(2) Quadrant – occlusive: ↑ inflow

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29
Q

What are the advantages of chop technique?

A
  • less power required (mechanical rather than phaco power)
  • less zonular stress (centripetal force)
  • time efficient – 1 crack = several passes for sculpting
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30
Q

What are the causes of zonular weakness?

A 
ESSENTIAL:
a) PXF		b) Very old	c) Mature cataract
d) Iris/lens colobomas	
e) Marfan’s/HomocysteinuriaWeill-Marchesani
ACQUIRED:
a) previous trauma	b) previous surgery
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31
Q

What are the causes for etopia lentis in a young patient and what are the associated systemic risks?

A

(1) Trauma
• Most common causes in young patient (cf. PXF most common in elderly)
(2) Marfan’s Syndrome
• Aortic root enlargement
• Aortic Regurgitation; Mitral valve disease
(3) Homocysteinuria
• Thrombotic tendency postop/postpartum
• Cystathionine-β-synthetase deficiency
(4) Weill-Marchesani
• “opposite of Marfan’s” - short stature etc
• Microspherophakia
(5) Ehers-Danlos
• Dissecting aneurysms / MVR; easy bruising

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32
Q

What are the options for coexistent Fuch’s endothelial Dystrophy and cataract?

A 
Determine based on Fuch's severity and cataract severity:
(1) FUCH'S MILD, CATARACT SIGNIFICANT
•	Rx - PKE/IOL
•	Low risk but may need 2 operations 
(2) FUCH'S MOD, CATARACT SIGNIFICANT
•	Rx - PKE+IOL/ DSEK
•	Probs of DSEK; ↓ risk of graft failure
(3) FUCH'S SEVERE, CATARACT mild
•	Rx - PK only
•	PKE+IOL can later correct refraction
(4) FUCH"S SEVERE, CATARACT SEVERE
•	Rx - PKE+IOL/ PK
•	Probs of PK; ↓ risk of graft failure
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33
Q

What are the special considerations/management options in patients Fuch’s Endothelial Dystrophy?

A
  • CONSENT - Longer recovery time - Consider triple procedure if morning CCT>640µm
  • Wounds in direction of iris plane - scleral tunnel vs limbal incision; temporal vs superior; small
  • Soft shell technique – Viscoat / Duovisc
  • Stain capsule if poor visibility
  • BSS plus (bicarbonate; dextrose; glutathione)
  • Low flow phaco (↓ bottle height; ↓ AFR; ↓ vacuum = ↓ turbulence)
  • Endocapsular phacoemulsification – i.e. under iris plane therefore phaco away from endothelium
  • Low IOP post op (avoiding CAI)
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34
Q

What are the special considerations/management options in patients with a Shallow AC?

A
  • CONSENT - Longer recovery time
  • Soft shell technique – Viscoat / Duovisc
  • Endocapsular phacoemulsification – i.e. under iris plane therefore phaco away from endothelium
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35
Q

What are the special considerations in patients with High myopia?

A
  • IOL selection: Haigis
  • ↑ risk of RD / suprachoroidal h’ge / high astigmatic change (thin sclera)/ hypotony / weak zonules / deep AC
  • Intervention: Small incision (<3mm); appropriate sized CCC; ↓ initial flow parameters will ↓ AC fluctuations
36
Q

What are the special considerations in patients with High hyperopia?

A
  • IOL selection: Hoffer Q

* Shallow AC; ? need for piggy-back IOLs (range in SA60WF +6D to +40D)

37
Q

What do you look for when positive pressure is encountered intraoperative and how do you overcome it?

A

CAUSES:
Tight lids; large volume of retrobulbar anaesthetic; retrobulbar h’ge; speculum pressure; obese patient with venous engorgement; Choroidal h’ge or effusion
INTERVENTION:
Trendelenberg position; check speculum; lateral catholysis; iv mannitol;

38
Q

What are the issues to consider with PXF?

A

Flopply iris; Poor dilation; Weak zonules; Glaucoma

39
Q

What adjustments do you make when operating on a white cataract?

A

VisionBlue; cohesive viscoelastic; aspirate cortical milk; small rhexis; hydro not essential

40
Q

What the issues and interventions when operating on a brunescent cataract?

A

ISSUES:
Long phaco times (corneal burns/corneal decomp);
INTERVENTION:
large rhexis (6-7mm); careful hydro-little cortex – may rupture; expose tip – more cutting efficiency; ↑ vacuum/flow rate/power – ↑ phaco efficiency; deep wide grove/phaco chop;
Long case ∴ monitor fluid

41
Q

How do you prevent PS formation in when operating for cataract in chronic iridocyclitis?

A

Intensive steroid (quiet for 3/12); Large optic (can be placed in sulcus); Heparin-surface modified lens

42
Q

How do you manage cataracts Post-Vitrectomy?

A

Issues: - deep AC fluctuating AC; flaccidity/excessive movement of PC; poor puplliary dilation; PC plaques;
Interventions: Lower bottle height - ↓AC depth; Acrylic, large optic size IOL

43
Q

How do you deal with a small pupil?

A

Methods to enlarge the pupil:
- I/C phenyl; Peripupil membraneectomy; Pupil stretch; Iris Hooks; Visco; Sectorial PI; Sphincter Cuts
Surgical Techniques:
- Small rhexis; Slow flow phacoemulsification

44
Q

How do you manage cases of zonular weakness?

A

– incision distant from area of weakness; start rhexis away from weakness; CTR; good hydro; low vacuum, low asp; low bottle height; divide&chop; manual cortex

45
Q

What are your indications for oral steroids perioperatively?

A

INDICATIONS:
1. Chronic AAU; 2. PostSynachie (likely iris manipulation); 3. CME; 4. Post Seg Uveitis; 5. Only eye
DOSE:
40mg/D 1/52 pre-op; taper by 5mg/week after

46
Q

What are the grades of zonular dehiscence?

A

1) 1-2 clock hours - IOL in bag

2) 2-6 clock hours no vitreous - IOL in bag with CTR (6 clock hours - ? fixated /AC IOL (MTA4UO) ?>4 clock hours

47
Q

What are the problems associated with converting from PKE to ECCE?

A

a) creating the wound
b) difficulty in removing the lens
c) duration of surgery
d) wound closure/stability
e) postop astigmatism
f) slower rehab
g) Expulsive SCH more likely

48
Q

What are the reasons for conversion to an ECCE?

A

1) Loss of control of CCC / radial tear
2) Lens too hard
3) Machine failure
4) Loss of view / poor corneal clarity

49
Q

What are the steps in converting in the presence of a radial tear?

A

a) Enlarge wound to 120o
b) Open the rhexis with Ong’s scissors
c) Elevate upper pole of lens
d) Introduce irrigating vectis behind the lens and advance
e) Float the lens out of the eye
f) Look for Vitreous
g) Remove soft lens material
h) Consider Sulcus fixation

50
Q

What are the signs of a posterior capsular rupture during PKE?

A

1) Vitreous in the AC
2) Sudden deepening of AC
3) Inability to PKE/aspirate – particles no longer come to tip
4) Distortion of CCC as instruments moved
5) Loss of lens fragment
6) Clear section of post capsule / Direct visualisation of PC defect

51
Q

What are the signs of a vitreous prolapse?

A

As for PC tear +

7) Lens material no longer centred
8) Pupil widens
9) Lens no longer rotates freely

52
Q

Rhexis runs out under pupil margin. What are the options now?

A

a) stop
b) fill with viscoelatic – reform the AC
c) attempt to tear back in by gripping close to the apex
d) start from other side – may need to restart with cystotome / scissors
e) leave the tag – hydrodelineate, PKE inside SLM; ↑ phaco power; crack in meridian away from radial tear
f) Consider converting to ECCE

53
Q

Compare and contrast shearing/ripping versus tearing when doing rhexis. When can that be useful?

A

Can be good for getting lost rhexis when goes out

54
Q

What are the advantages of a CCC over can-opener capsulotomy?

A

1) Inherently stronger

2) Less chance of haptic migration

55
Q

What are the relative contraindications to proceeding with phaco in the presence of a tear?

A

1) Small pupil - No view
2) Young eye - Springy zonules
3) High myopia - vitreous pressure, scleral collapse
4) Hard lens - Extended surgery
5) Restless patient - Unpredictable control
6) PXF - Further complications
7) Large lens - Risk of further extension of the tear

56
Q

What are the risk factors for intraoperative suprachoroidal haemorrhage?

A

1) Old age
2) High myopia
3) High IOP
4) High BP
5) Atherosclerosis
6) Recent Ocular trauma / surgery with active inflammation
7) Intraoperative valsalva manoeuvre

57
Q

How do you manage an acute intraoperative suprachoroidal haemorrhage?

A

1) Close the wound quickly and tightly – 8/0 or 7/0 Nylon
2) If explusive perform sclerotomies 1.5mm in D
3) Wait for the clot to liquefy (3-5 days)

58
Q

What are the causes of wound burn?

A 
INSUFFICIENT COOLING
•	Reduced inflow
1. Bottle too low or empty
2. Improper Setup
3. Sleeve Kinking
4. Tight Incision
5. Handpiece manipulation
•	Reduced outflow
1. Viscoelastic Occlusion
2. Obstruction Nuclear Chip
3. Tip Embedded in Nucleus
4. Insufficient Asp Rate
5. Insufficient Vacuum
EXCESSIVE HEATING
•	Excessive ultrasound
1. High power / Not using phaco-chop
2. Continuous Ultrasound (to overcome use burst – tap foot etc)
•	Excessive friction
1. Tight incisions
2. Excessive handpiece angle
3. Handpiece manipulation
59
Q

What are the signs and longterm complications of wound burn?

A

Intraoperative signs: Lens Milk; wound contraction.

Complications: Wound leak; Astigmatism; endophthalmitis

60
Q

What are the principles of managing PC tears?

A

i. Keep instruments in the eye
ii. Lower bottle height to 20cm
iii. Inject dispersive viscoelastic – Viscoart/Ocucoat +/- triamcinolone
iv. Remove remaining cortical/nuclear fragments from the posterior chamber
v. Perform an Anterior Vitrectomy – irrigate high/cut low (? with triamcinolone intracameral?)
Dry Vitrectomy – if not much vit prolapse
a. ASP 25cc/min
b. Vacuum 11mmHg
c. Cut rate >800
d. Port wide open
vi. Insert an IOL – sulcus (if ≥7 clock hours of support) or bag (MA60AT) – no IOL if >1/2 nucleus dropped
vii. Add Miochol
viii. Perform a Weck cell vitrectomy – sponge to wound + Wescott scissors - SUTURE WOUNDS
ix. Refer electively to a vitreoretinal surgeron for nucleus removal in 7-14 days if fragment ≥2mm

61
Q

What are the intraoperative features of IFIS?

A
  1. Iris prolapse,
  2. iris that billows up with irrigation,
  3. progressive pupillary constriction
62
Q

What are the causes of iris prolapse?

A
  • Poor wound construction – too short – too posterior
  • Poor wound sealing
  • Sudden ↑ IOP - Expulsive SCH
  • Atonic/damaged iris
63
Q

How do you manage a Descemet tear?

A

a) Take care not to extend it
b) If small 1/5 1. add SF6 0.1ml of 100% or enough of 50% to ½ fill AC + posture post-op
2. Suture

64
Q

What are the differential diagnosis of a shallow AC immediately postop?

A

1) Wound leak
2) Pupillary block
3) Aqueous misdirection
4) Choroidal effusion
5) Suprachoroidal haemorrhage
6) Capsular block

65
Q

What are the causes of postoperative hypotomy?

A

1) Wound leak
2) Inadvertent cyclodialysis
3) Retinal Detachment
4) Choroidal effusion with ciliary body detachment

66
Q

What are the causes of raised IOP in the immediate postoperative period?

A

1) retained viscoelastic
2) pre-existing glaucoma
3) dislocated lens fragment
4) pupil block / iris bombe
5) Uveitis
6) Hyphaema
7) Expulsive Haemorrhage

67
Q

What are the common problems causing patients to represent on the day of cataract surgery?

A

a) Corneal abrasion
b) Raised IOP – retained visco
c) Leaking wound
d) Suprachoroidal h’ge
e) TASS

68
Q

What are the common problems causing patients to present on the day after cataract surgery?

A

a) Corneal oedema (Pre-op: FED; Intra-op: Trauma/DM detach Toxins; Post-op Glc/visco)
b) Raised IOP
c) Diplopia
d) Wound leak
e) Iris prolapse
f) Vitreoys prolapse
g) Retained lens matter
h) Hypopyon
i) SupraCH
j) Uveitis
k) Wrong IOL power

69
Q

What are the causes for corneal oedema on the first postoperative day?

A

1) raised IOP
2) striping of Descemet’s membrane
3) Prolonged surgery
4) Pre-existing endotheliopathy – Fuch’s

70
Q

What are the problems which present in the first week after surgery?

A

a) Uveitis
b) Endophthalmitis
c) Glaucoma
d) Corneal Oedema

71
Q

What are the problems which present in the 1-8 postoperative weeks?

A

a) Persistent uveitis
b) Cystoid Macular Oedema
c) Lens deposits
d) Raised IOP
e) Persistent corneal Oedema
f) Refractive surprise
g) Astigmatism
h) Capsular phimosis
i) RD

72
Q

What are the factors which contribute to PCO formation?

A
  • Hydrodissection-enhanced cortical clean up
  • Biocompatible IOL ↓ stimulation of cellular proliferation
  • In the bag capsular fixation
  • IOL geometry – square, truncated edge
  • Small CCC with edge on IOL surface
  • Maximal posterior optic capsule contact – shrink wrap
73
Q

What are potential complications of Nd:YAG capsulotomy?

A

1) Elevated IOP
2) Lens pits/cracks
3) Lens decentration/dislocation
4) Retinal Detachment
5) Macular Hole
6) Uveitis

74
Q

What is the cause for chronic postoperative uveitis?

A 
Early		
a) Infective
b) Retained lens matter
c) Aseptic – secondary to tissue manipulation
d) TASS
Persistent	
a) Poor compliance / Steroids tapered too quickly
b) Retained lens matter	
c) Iris or vitreous incarceration
d) UGH
e) RD
f) Low grade endophthalmitis – P. acnes
g) Pre-existing uveitis
h) SO
75
Q

What is the highest cause of litigation after performing cataract surgery?

A
  • Refractive surprise (50% are A-scan related)
76
Q

What are the important considerations with post-operative refractive surprise?

A
  1. Check preoperative errors - biometry; transcription error; formulae used; wrong patient; previous refractive surgery
  2. Intraoperative errors - wrong lens selected or implanted
77
Q

How do you correct post-cataract refractive surprises?

A
  1. IOL exchange if <3/12
  2. Piggyback IOL
  3. Refractive excimer laser – LASIK best procedure of choice in hyperopes
78
Q

How do you investigate an outbreak of endophthalmitis/TASS?

A
  1. Immediate - cease all operating; activate infection control team;
  2. Open disclosure – notify al affected pts – ensure close follow-up
  3. Notify all stakeholders – other surgeons; anaesthetists;
  4. Active infection control team
    – perform root cause analysis
    - identify causative agent by looking for commonality
    - review microbiology; location; batches
    - check procedures and equipment
79
Q

Compare the clinical features of TASS to infective endophthalmitis.

A 
•	TASS:
Onset of symptoms 12-48 hours
Generally no pain
Corneal oedema limbus-to-limbus
AC inflammation +++ 
Possible iris atrophy with dilated nonreactive pupil
Vitreous usually clear
Good and rapid response to steroids
•	INFECTIOUS ENDOPHTHALMITIS:
2-7 days (unless v.agressive)
Pain in greater than 75% of patients
Focal corneal oedema possible
AC inflammation +++
Iris/pupil changes relatively uncommon
Vitreous opacified. 
Minimal response to steroids
80
Q

When do you intervene for a dislocated IOL?

A
  1. If causing symptoms (UVP etc)

2. If causing complications (UGH; CMO; recurrent pupil block; IOL-corneal touch etc.)

81
Q

What proportion of patients with endophthalmitis achieve a VA of 6/24 or better?

A

1) Staph. Epidermidis - 84%
2) Staph. Aureus - 50%
3) Streptoccocal species - 30%
4) Gram Negatives - 56%

82
Q

What are the important factors for phakic IOL consideration?

A

1) Pupillometry 8mm
2) ACD >3.2mm
3) Endothelial cell count

83
Q

Outline the methods for refractive surgery.

A

PRK - photorefractive keratectomy - epithelium removal then excimer laser (193nm)
LASEK - Laser subepithelial keratectomy - epithelium chemically separated from Bowman’s
epi-LASIK - epithelial-laser in situ keratomileusis - epithelium mechanically separated
LASIK - laser in situ keratomileusis - hinged partial thickness flap

84
Q

When to do you choose PRK over LASIK?

A
  1. Thin cornea – remember the residual stromal bed needs to be > 250mm. EBMD
  2. Dry eyes – PRK doesn’t cause dry eye (as per Nick Downie)
  3. Corneal scar and refractive error
  4. Occupation and risk of trauma
85
Q

What are the complications of LASIK?

A 
INTRA-OPERATIVE:
•	Microkeratome complications
•	Epithelial erosions
•	Central islands and decentration 
•	Very high pressures of microkeratome 
IMMEDIATE POST-OPERATIVE:
•	Striae
•	Lost flap
LATE POST-OPERATIVE
•	Diffuse Lamellar Keratitis (DLK) 
•	Infective keratitis
•	Dry eyes and decreased corneal sensation
•	Traumatic flap dislocation
•	Epithelial ingrowth
•	Epithelial ingrowth (<3%)
•	Ectasia

Cataract and Refractive (1 decks)

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