Optimized Zernike Terms Selection In Customized Treatments For Laser Corneal Refractive Surgery
Final clinical outcomes of laser refractive surgery
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Transcript of Final clinical outcomes of laser refractive surgery
Central Coast Day Hospital
Inaugural Optometrist Conference
26th February 2012
Anil Arora
Swetha Velpula
Laser Refractive Surgery In General
Current refractive lasers can treat up to 10-11 dioptres spherical equivalent of myopic astigmatism and up to 4.5 to 5.0 dioptres spherical equivalent of hyperopic astigmatism
LASIK far more commonly performed than PRK – less patient discomfort, faster recovery, no corneal haze
Extremely accurate but undercorrections and overcorrections still occur because of variations in healing response between different individuals
Laser Refractive Surgery In General Despite highly sophisticated technology, still need careful
preoperative evaluation.
Corneal topography is essential in all patients
Corneal pachymetry is essential in all patients
Wavefront guided treatments seldom used in routine cases because of high accuracy of current generation machines and nomograms
Keratoconus and pellucid marginal degeneration are absolute contraindications
Careful refraction required. No contact lens wear for 3 days prior to assessment as CL wear can affect refractive measurements.
Screening refraction results by staff rechecked by surgeon at a second visit
LVCCC – Results at one year Retrospective analysis of patients
treated at LVCCC during 2011
114 eyes of 64 patients
50 patients had bilateral laser procedures
14 patients had only one eye treated
106 eyes underwent LASIK – 74 eyes for bilateral emmetropia, 32 eyes for monovision
8 eyes underwent PRK – all for bilateral emmetropia
Zeiss Visumax and MEL 80 lasers
Type of surgery performed 2011
LASIK74 Eyes (65%)
PRK8 Eyes(7%)
Mono Vision32 Eyes(28%)
Type of Surgery
LASIK
PRK
Mono Vision
LVCCC – Other laser procedures performed in 2011 3 other groups of procedures performed that are not
included in this review
LASIK or PRK refractive enhancement following cataract surgery –12 eyes of 10 patients
Phototherapeutic keratectomy (PTK) for calcific band keratopathy – 8 eyes of 6 patients
PTK for recurrent erosion syndrome – 4 eyes of 2 patients
Gender of patients having laser refractive surgery 2011
26 (40%)
38(60%)
Gender
Male Female
Total : 64 Patients
Female
Male
Age distribution of patients having laser refractive surgery 2011
0
20 (31.3% )
18 (28.1%)
18 (28.1%)
8 (12.5%)
0
5
10
15
20
25
30
35
40
45
18-20 21-30 31-40 41-50 51-60
No
. of
Pa
tie
nts
Years
AGE RANGE
LASIK – Post-op unaided VA 1 Month
0
5
10
15
20
25
30
35
6/5 or better 6/6 6/9 6/12 Less than 6/12
No
. O
f E
yes
Unaided Visual Acuity
LASIK : Post- Operative UA VA - 1 Month
20 (27%)
2 (2.7%)
32 (43%)
20 (27%)
PRK (ASLA) – Post-op unaided VA 1 M
6 (75%)
2 (25%)
0
1
2
3
4
5
6
7
6/6 6/9
No
. of
Eye
s
Unaided Visual Acuity
PRK: Post- Operative UA VA- 1 Month
Monovision Useful option in the management of presbyopia
Often results in good patient outcomes with most studies reporting about 70% satisfaction rate with monovision
Results are similar to those obtained with contact lens wear or with lenses in a trial frame so patient can be given a trial of these to assess suitability for monovision
Is a “compromise” – patient education and setting realistic expectations essential during pre-op testing
Can be achieved with LASIK or PRK
“Near” eye can be retreated post-operatively to achieve bilateral emmetropia if patient unhappy with monovision
Monovision 32 eyes received treatment to specifically produce a
monovision result. All had LASIK.
Dominant eye for distance – 18 eyes
Non-dominant eye for near – 14 eyes
12 patients underwent bilateral treatment - mostly hypermetropic presbyopes (9 patients) but also myopic presbyopes (3 patients)
8 patients underwent unilateral treatment 2 emmetropic presbyopes had myopia induced in their non-
dominant eye
6 myopic presbyopes had their dominant myopic eye made emmetropic
Monovision – Unaided dist VA at 1 M
8 (44.5%)
10 (55.5%)
0
2
4
6
8
10
12
6/5 or better 6/6
No
. of
Eye
s
UA Distance VA (1 Month)
MV Distance Eye: Post-op UA VA-1 Month
Monovision – Unaided near VA at 1 M
10 (71.5%)
4 (28.5%)
0
2
4
6
8
10
12
N5 N6
No
. O
f E
yes
UA Near VA (1 Month)
MV Near Eye: Post-op UA VA-1 Month
Results From Singapore National Eye Centre (Uses Visumax Femto)
37,932 eyes of 19,573 patients underwent LASIK from 1998 to 2007.
Uncorrected visual acuity (means without glasses or contact lenses) achieving 20/40 or better has been consistently above 90% since the year 2000, with 72.8% achieving 20/20 or better. More than 93.0% of eyes achieved within +/- 1.00D target in the last four years.
The overall uncorrected visual acuity (UCVA) for Snellen 20/40 or better postoperatively has been consistently above 90% since the year 2000, with a positive trend achieving 98.0% in the year 2007.
Our Results 6/6 or better unaided
Bilateral LASIK – 70% (52/74 eyes) PRK – 75% (6/8 eyes) Monovision (with LASIK) - 100% (18/18 eyes) OVERALL – 76% (76 out of 100 eyes) 6/6 or better unaided
6/9 or better unaided Bilateral LASIK - 97% (72/74 eyes) PRK - 100 % (8/8 eyes) Monovision (with LASIK) – 100%(18/18 eyes) OVERALL – 98% (98 out of 100 eyes) 6/9 or better unaided
Complications The main “complication” in laser refractive surgery is under-
or over-corrections with most centres reporting a retreatment (enhancement) rate of between 1 and 8%(SNEC 6.2%)
This has been our finding also. So far only 2 eyes have had to be retreated giving us an enhancement of just under 2% (2/114). These were both for undercorrections. The treated eyes achieved 6/5 and 6/6 unaided vision after the enhancement
66% of eyes with +/- 0.5D of target refraction
94% of eyes within +/- 1D of target refraction
Retreatments/Enhancements Usually carried out at 3 months to ensure refractive stability. Still
easy to lift the flap for many months (even 1-2 years)after LASIK. However, flap dislocation extremely rare after one month
Flap recut seldom required.
Our results indicate refractive stability after 1 month (little or no change between 1 -3 months). May consider earlier retreatments
More than one retreatment may be required. Has not been our experience so far.
Need to ensure that there is still enough residual corneal tissue for retreatment. Ideally need 300um or more of residual stromal tissue. Retreatment may not be possible if RST too low.
Complications - Intraoperative Incomplete flap – 0
Dislodged flap – 0
Buttonhole – 0
Eccentric flap – 2
Decentred ablation zones – 0
Loose epithelium - 6
Complications - Postoperative Infection – 0
Flap dislocation – 0
Diffuse lamellar keratitis – 0
Epithelial ingrowth – 0
Post-LASIK ectasia – 0 (so far!)
Flap striae - 6 cases – all resolved over 1-2 weeks with the use of corticosteroid eye drops
Interface debris – 8-10 cases of minor interface debris. None visually significant. None requiring a flap lift and cleaning
Dry eye – transient. Only 2 patients with prolonged dry eye symptoms. Using frequent ocular lubricants
Corneal haze – 0 in LASIK patients, transient in 4/8 PRK patients
Conclusion Still a “young” centre with small numbers to date
Excellent results (in terms of percentages) on par with some of the largest refractive centres worldwide
Very low complication rate – again on par with larger and more established centres
An asset to patient treatment on the Central Coast with a facility to treat refractive errors, presbyopia, post-cataract refractive surprises, and also phototherapeutic keratectomy for band keratopathy and recurrent corneal erosion syndrome
QUESTIONSQ1 Which is true about the indications for LASIK?
It has no role in the management of hyperopia
It can treat almost any degree of myopia
It can treat about 11 dioptres of combined sphere and cylindrical correction in myopia
It can treat up to 11 dioptres of combined sphere and cylindrical correction for hyperopia
Q2 Which of the following is true concerning the pre-
operative LASIK consultation?
Corneal topography is essential
Corneal pachymetry is only necessary in selected cases
Recent contact lens wear does not affect the measurements made
Keratoconus is not a contra-indication to LASIK
Q3 When considering monovision in the context of
LASIK which of the following is true?
Monovision generally produces unsatisfactory results
It is difficult to change monovision once it has been created
Results are similar to those achieved with contact lenses
Monovision cannot be created by LASIK
Q4 Which of the following are true about LASIK
enhancement?
It is necessary to recut the flap
It is impossible to lift the flap after a month post-operatively
Several enhancements can be performed if necessary
It is always possible to perform an enhancement
Q5 Which of the following is true about LASIK
complications?
The flap may easily detach up to several months following the procedure
Halos when driving at night sometimes occur post-operatively
Haze (scarring) commonly occurs after myopic LASIK
Under or over correction are very rare events
ANSWERS Q1 - C
Q2 - A
Q3 - C
Q4 - C
Q5 - B