Laser in situ keratomileusis for refractive error after cataract surgery

$Page 1: Laser in situ keratomileusis for refractive error after cataract surgery$
Laser in situ keratomileusis for refractiveerror after cataract surgery

Peter Kim, MBBS(Hons), Esther M. Briganti, FRACP, MclinEpi,Gerard L. Sutton, FRACS, FRACO, Michael A. Lawless, FRACO, FRACS, FRCOphth,Christopher M. Rogers, FRACO, FRACS, Chris Hodge, BAppSc (Orth)

Purpose: To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) tocorrect refractive error following cataract surgery.

Setting: The Eye Institute, Sydney, Australia.

Methods: This retrospective study reviewed 23 eyes (19 patients; 10 female, 9 male)treated with LASIK for refractive error following cataract surgery. The Summit ApexPlus and Ladarvision excimer laser and the SKBM microkeratome were used. Themean age was 63.5 years (range 50 to 88 years). The mean length of follow-up was8.4 months (range 1 to 12 months) and mean interval between cataract surgery andLASIK was 12 months (range 2.5 to 46 months).

Results: The mean preoperative spherical equivalent refraction (SEQ) for myopiceyes was�3.08G 0.84 diopters (D) (range�4.75 to�2.00 D) and for hyperopic eyeswas C1.82 G 1.03 D (range C0.75 to C3.00 D). The mean improvement followingLASIK surgery was greater for myopic than hyperopic eyes (myopic, 2.54 G 1.03 Dversus hyperopic, 1.73 G 0.62 D; PZ .033). The percentage of patients withinG0.5 D of intended refraction post-LASIK surgery was 83.3% for myopic eyes and90.9% for hyperopic eyes and all eyes were withinG1.0 D of intended (P!.001).Thepercentage of eyes with uncorrected visual acuity of 20/40 or better in the myopicgroup improved from none preoperatively to 91.7% postoperatively (P!.001) and inthe hyperopic group improved from 27.3% preoperatively to 90.9% postoperatively(PZ .008). No eyes lost 2 or more lines of best corrected visual acuity.

Conclusion: Laser in situ keratomileusis appears to be effective in correctingrefractive error following cataract surgery. Longer-term studies are required todetermine refractive stability.

J Cataract Refract Surg 2005; 31:979–986 ª 2005 ASCRS and ESCRS

Cataract surgery with intraocular lens (IOL) im-

plantation is a common and efficient procedure

with excellent visual outcomes. However, unsatisfactory

visual outcomes as a result of refractive error occasion-

ally occur, despite the procedure being technically

excellent.

Various options are available to correct refractive

error following cataract surgery, including correction

with spectacles or contact lenses. However, patients may

be intolerant of these techniques due to anisometropia

or refusal to wear corrective lenses and surgical options

may have to be considered. These include exchanging

the IOL especially in the early postoperative period,

ª 2005 ASCRS and ESCRS

Published by Elsevier Inc.

implanting a piggyback IOL, or performing corneal

refractive surgery.1,2

Photorefractive keratectomy (PRK) and laser in situ

keratomileusis (LASIK) have been the preferred surgical

techniques by refractive surgeons. Both procedures are

effective, although LASIK is now considered to be more

effective, more immediately predictable, and results in

less regression than PRK.3–5 Concerns about LASIK

safety after cataract surgery have been raised with regard

to lens dislocation and retinal problems.6,7

There have been a few studies looking at the

effectiveness of LASIK in the correction of refractive

error following phacoemulsification cataract surgery,

0886-3350/05/$-see front matter

doi:10.1016/j.jcrs.2004.08.054

LASIK AFTER CATARACT SURGERY

and they have reported good safety and effectiveness.6–8

LASIK appears to be effective in pseudophakic patients

as well as following corneal and other intraocular

procedures.6–9

This paper presents results assessing the efficacy, sta-

bility, and safety of LASIK in treating residual myopic

and hyperopic refractive error following cataract surgery.

Patients and MethodsThis retrospective study involved the review of 23 eyes

(12 right, 11 left) from 19 patients treated with LASIK forrefractive error following phacoemulsification cataract sur-gery with IOL implantation. All patients were referred to TheEye Institute, Sydney, Australia, between June 1998 andMarch 2002. Patients were included in the study if they hadprevious uncomplicated cataract surgery and subsequentLASIK surgery for the correction of residual refractive error.Patients in this study had healthy anterior segments and nohistory of glaucoma or ocular trauma. Exclusion criteriaincluded previous corneal transplantation, ocular surgeryother than phacoemulsification cataract surgery, and presenceof corneal or other ocular pathology.

Informed consent was obtained for every patient prior tothe LASIK procedure. A written fact sheet was provided toevery patient describing the surgical procedure and relatedrisks.

This study included 10 female and 9 male patients witha mean age of 63.5 years (range 50 to 88 years). Four patientshad bilateral and 15 had unilateral LASIK surgery. The meanlength of follow-up was 8.4 months (range 1 to 12 months).The mean interval between cataract surgery and LASIK was12months (range 2.5 to 46months). The reasons for wantingLASIK surgery included intolerance of glasses and contactlenses, lifestyle factors, and occupational requirements.

A complete ophthalmic examination was performed pre-LASIK and post-LASIK surgery. This included visual acuity,manifest and cycloplegic refractions, corneal topography,

Accepted for publication August 27, 2004.

From Liverpool Hospital (Kim), Sydney, Australia, the Department ofEpidemiology and Preventive Medicine (Briganti), Monash University,Melbourne, Australia, the Sydney Eye Hospital (Sutton), Sydney,Australia, and the Eye Institute (Sutton, Lawless, Rogers, Hodge),Sydney, Australia.

No author has a financial or proprietary interesting any material ormethod mentioned.

This paper was presented on November 18, 2002, at the RANZCO34th Annual Scientific Congress, Canberra, Australia.

Reprint requests to Gerard L. Sutton, FRACS, FRACO, FRCOphth,Level 3, 270 Victoria Avenue, Chatswood 2069, Sydney, Australia.E-mail: [email protected].

980 J CATARACT REFRACT SU

slitlamp examination, tonometry, fundus examination, andcorneal thickness measurement. At preoperative and post-operative follow-up visits (1 day, 1 week, 1 month, 3 months,6 months, and 12 months), patients were reviewed withmanifest refraction, keratometry, intraocular pressure (IOP),uncorrected visual acuity (UCVA) and best visual acuity(BCVA), and slitlamp examination.

Preoperatively, the patient had topical treatment withamethocaine 0.5%, tropicamide 1%, and phenylephrine10% eyedrops. All surgeries were performed using eitherthe Summit Apex Plus Laser (Alcon) or Ladarvision Laser(Alcon) in combination with the SKBM microkeratome(Alcon). The ablations were performed using argon-fluoride193 nm laser at a mean fluence of 180 mJ/cm2 and repetitionrate of 10 Hz (Summit Apex Plus) or at a fluence of between180 to 240 mJ/cm2 and repetition rate of 60 Hz (AlconLADARVision). Ablations were completed with either a6 mm or 6.5 mm optical zone. The LASIK surgery techniqueused is described in detail in Comaish et al.9 Those eyesexperiencing tracking difficulties were not included in thisstudy.

Most patients had emmetropia as the aim of theirrefraction. However, some patients preferred a refraction oflow myopia of �0.5 diopters (D).

The method for treating cylindrical ablations differeddepending on the type of laser used. For the Summit ApexPlus laser at surgery an astigmatic erodible disk was placed inthe down rail prior to ablation to allow for the propercorrection of the cylinder. The axis of the astigmaticcorrection was adjusted on the mask cartridge prior toplacement.10 In contrast, the total treatment was entered intothe LADARVision laser for direct ablation.

Postoperative treatment included an eye shield, cyclo-pentolate 1%, ofloxacin 0.3% 4 times a day for 1 week, andprednisolone acetate 1%. Analgesia with paracetamol 1 g wasgiven orally 4 times a day.

Statistical AnalysisPaired Student t test was used to compare preoperative

and postoperative data. For analysis of residual refractiveerror, a 1 sample Student t test was used, comparing theresidual refractive error (postoperative minus aimed forspherical equivalent refraction [SEQ]) with the intendedSEQ. McNemar’s chi-square test was used to comparepreoperative and postoperative proportions. Comparison ofoutcomes between myopic and hyperopic eyes was performedusing the unpaired t test. A P value of less than .05 wasconsidered statistically significant. All analyses were con-ducted using Stata version 6.0 (Stata Corporation, CollegeStation, Texas, 1999).

ResultsTable 1 shows the mean and range of preoperative

and postoperative SEQ for myopic and hyperopic eyes.

RG—VOL 31, MAY 2005

mailto:[email protected]


Table 1. The preoperative and postoperative spherical equivalent refractions and postoperative residual refractive error in study eyes.

Number Myopic Eyes Hyperopic Eyes

Preoperative and Postoperative Spherical Eqivalent Refraction 12 11

Preoperative

Mean SEQ G SD, D �3.08 G 0.84 C1.82 G 1.03

Range SEQ, D �4.75 – �2.00 C0.75 – 3.00

Postoperative

Mean SEQ G SD, D �0.54 G 0.59 C0.09 G 0.36

Range SEQ, D �1.5 – 0.5 �0.25 – 0.75

P value* !.001 !.001

Postoperative residual refractive error

Mean SEQ G SD, D �0.40 G 0.22 C0.22 G 0.26

Range SEQ, D 0.00 – �0.75 0.00 – 0.75

P value† !.001 .019

SDZ standard deviation

*P value for the difference between preoperative and postoperative SEQ†P value for the difference between postoperative SEQ and the intended SEQ

The degree of refractive error preoperatively was greater

in myopic (12) eyes than hyperopic (11) eyes (myopic,

3.08 G 0.84 D versus hyperopic, 1.82 G 1.03 D;

P!.001). The mean improvement was greater for

myopic than hyperopic eyes (myopic, 2.54 G 1.03 D

versus hyperopic, 1.73 G 0.62 D; PZ .033).

There was a trend for the residual refractive error

(difference between postoperative SEQ and intended

SEQ) to be greater in myopic than hyperopic eyes

(myopic �0.40 G 0.22 D versus C0.22 G 0.26 D;

PZ .077). However, the range of residual refractive

error was small (0.00 to 0.75 D).

Figures 1, A and B show the postoperative SEQ for

myopic and hyperopic eyes, respectively. The per-

centage of eyes within G0.5 D of intended refraction

post-LASIK surgery was 83.3% for myopic eyes and

90.9% for hyperopic eyes, and all eyes were within

G1.0 D of intended.

Figures 2, A and B are scattergrams of intended

versus achieved SEQ for myopic and hyperopic eyes,

respectively.

Figures 3, A and B show the preoperative and

postoperative distribution of UCVA in myopic and

hyperopic eyes, respectively. The percentage of patients

with UCVA of 20/40 or better in myopic eyes was none

preoperatively improving to 91.7% postoperatively

(PZ .001). In hyperopic eyes, patients with UCVA

J CATARACT REFRACT SU

of 20/40 or better was 27.3% preoperatively and 90.9%

postoperatively (PZ .008).

Figure 4 shows the change in lines of BCVA in

myopic and hyperopic eyes postsurgery. Only 1 eye

(4.4%) experienced a loss of BCVA, from 20/20 to

20/25. No significant corneal haze was observed in any

eye, but 2 eyes had some minor inconsequential

epithelial ingrowth.

The mean preoperative anisometropia was 1.71 D

and postoperative anisometropia 0.62 D, a significant

reduction of 1.09D (PZ .0001). Twelve of 19 patients

(63.2%) had anisometropia less than or equal to 0.5 D,

postoperatively.

DiscussionThe most frequent complication following cataract

surgery is residual refractive error resulting in sub-

optimal visual outcomes. This may be due to bio-

metrical errors, errors with IOL calculation and

selection, displacement of the IOL in the capsular bag

and other reasons.2,11,12 In some cases, the residual

refractive error may be significant and enhancement

procedures may be considered. Refractive surgery is

considered by some to be the best option for smaller

refractive errors if patients are spectacle intolerant.8

There have been rapid developments in laser

technology and techniques and this is reflected in

981RG—VOL 31, MAY 2005


0.0% 0.0%

16.7%

58.3%

25.0%

0.0% 0.0% 0.0%0%

10%

20%

30%

40%

50%

60%

70%

-3.0 to -2.1 -2.0 to -1.1 -1.0 to -0.51 -0.5 to 0 0.01 to 0.5 0.51 to 1.0 1.1 to 2.0 2.1 to 3.0

Postoperative Spherical Equivalent Refraction (D)

% o

f E

yes

12 Eyes1 Month Postop

+/- 0.5D 83.3%+/- 1.0D 100.0%

A

0.0% 0.0% 0.0%

63.6%

27.3%

9.1%

0.0% 0.0%0%

10%

20%

30%

40%

50%

60%

70%

-3.0 to -2.1 -2.0 to -1.1 -1.0 to -0.51 -0.5 to 0 0.01 to 0.5 0.51 to 1.0 1.1 to 2.0 2.1 to 3.0

Postoperative Spherical Equivalent Refraction

% o

f E

yes

11 Eyes 1 MonthPostop

+/- 0.5D 90.9%+/- 1.0D 100.0%

B

Figure 1. A: Graph of postoperative

SEQ for myopic eyes. B: Graph of post-

operative SEQ for hyperopic eyes.

a tendency for better refractive results and visual

outcomes in more recent abstracts and published

data.13,14 There are distinct advantages of LASIK over

PRK that include lower epithelial corneal haze, lower

regression, higher predictability, reduced incidence of

infection, less postoperative discomfort, and faster

visual recovery.4,15–18 In particular, the results of LASIK

for high myopia (O6.0 D) are superior to PRK.14

There is an abundance of literature validating the

safety and predictability of LASIK to correct refractive

error in the range �8.0 D to C4.0 D including

astigmatism in virgin eyes.13,19 In contrast, there is only

sparse literature supporting the use of LASIK for

correction of ametropia following ocular surgery such


as phacoemulsification surgery with IOL implanta-

tion.6,8 Laser in situ keratomileusis surgery has also been

shown to be effective for other indications such as

correction of refractive error following PRK,9,20,21

radial keratotomy,22,23 phakic IOL insertion,7 and

retreatment LASIK surgery.24–27

In this study, the percentage of patients with UCVA

of 20/40 or better in myopic eyes was none pre-

operatively and 91.7% postoperatively. For hyperopic

eyes this was 27.3% and 90.9%, respectively. This was

a substantial improvement for both groups. The

percentage of patients within G0.5 D of intended

refraction post-LASIK surgery was 83.3% in myopic

eyes (PZ .002) and 90.9% in hyperopic eyes



0

1

2

3

4

5

0 1 2 3 4 5Attempted (D)

Ach

ieve

d (

D)

Overcorrected

Undercorrected

11 eyes1 Month Postop

A

0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3 3.5

Attempted (D)

Ach

ieve

d (

D)

Overcorrected

Undercorrected

11 Eyes1 Month postop

B

Figure 2. A: Scattergram of the in-

tended versus the achieved SEQ for

myopic eyes. B: Scattergram of the in-

tended versus the achieved SEQ for

hyperopic eyes.

(PZ .002). All eyes in both myopic and hyperopic

groups were within G1.0 D of intended. This is

comparable with Montes et al.15 in their study of 396

virgin eyes with LASIK for myopia of �1.5 to �6.0 D.

They found that UCVA was 20/20 or better in 81%

(136 eyes) and 20/40 or better in 100% of eyes. Ninety

four percent had a mean postoperative SEQ within

G0.5 D of emmetropia and all eyes were withinG1 D.

Similarly, Ahn et al.3 and Dulaney and coauthors18 for

correction of refractive error with LASIK in virgin eyes

had postoperative UCVA of 91.3% (815 eyes) and 91%

(113 eyes) at 20/40 or better, respectively. This indicates

that the visual outcome of LASIK following cataract

surgery with IOL insertion is comparable to those of

virgin eyes.


In addition, the results in this study are superior

to Ayala et al.6 in their series of refractive correction

with LASIK after cataract surgery. In their study, 1 of

22 patients (4.5%) had UCVA of 20/40 or better

preoperatively and this improved to 10 of 22 patients

(45.4%), postoperatively. Following LASIK, 11 of 22

eyes (50.0%) had SEQ within G0.5 D of emmetropia

and 18 eyes (81.8%) were within G1.0 D of

emmetropia.

In this study, there was a small improvement in

BCVA following LASIK surgery in both myopic and

hyperopic eyes. This was not statistically significant due

to our small study numbers. The reason for this

improvement in BCVA postoperatively was not entirely

clear and may have been a result of measurement error.

983RG—VOL 31, MAY 2005


0.0%

0.0%

0.0%

0.0%

0.0%

0.0%

16.7

%

50.0

%

25%

67%

92%

100%

100%

100%

0.0%

0.0%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

16 20 25 30 40 50 100 200Cumulative Snellen Visual Acuity (20/_)

% o

f E

yes

Preop BCVA

Postop UCVA

12 Eyes1 Month Postop

A

0% 0% 0% 0%

27%

36%

100%

100%

100%

100%

100%

91%

91%

0%

36.4

%

64%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

16 20 25 30 40 50 100 200Cumulative Snellen Visual Acuity (20/_)

% o

f E

yes

Preop BCVA

Postop UCVA

B

Figure 3. A: Uncorrected visual acuity

preoperatively and postoperatively for

myopic eyes. B: Uncorrected visual acuity

preoperatively and postoperatively for

hyperopic eyes.

All patients had BCVA of 20/40 or better post-

operatively. Only 1 eye had deterioration of BCVA

from 20/20 to 20/25.

Montes et al.,15 studying LASIK for myopia –1.5 to

–6.0 D in virgin eyes, found only 2 eyes (1.2%) that lost

1 line of BCVA due to decentered ablation and no eyes

lost 2 or more lines of BCVA. This shows that LASIK

following cataract surgery is also safe and comparable to

the results in virgin eyes.

Only 2 eyes (8.7%) had minor epithelial ingrowth,

which did not require treatment. This is comparable to

studies on virgin eyes which found incidences of 9.1%28

and 8.6%.29 The majority of epithelial ingrowth

appears to either resolve spontaneously or remain at


a clinically insignificant level. There was no obvious

increased incidence of dry eye symptoms in our study

cohort and only a few patients required artificial tear

replacement.

No complications were observed in this study

relating to the retina, IOL position (lens dislocation, or

decentration), or the cataract incision site.

No patient included in this study had glaucoma or

developed high intraocular pressure and related com-

plications following LASIK surgery. This is of interest

as this comparatively older study population may

have a theoretically higher risk of developing compro-

mised optic nerve head circulation. In addition, a few

studies30,31 have shown that the measured IOP may



0.0%

4.4%

52.2%

34.8%

8.7%

0%

10%

20%

30%

40%

50%

60%

Loss of 2 lines Loss of 1 line No change Gained 1 line Gained 2 Lines

Change in Snellen lines of visual acuity

% o

f E

yes

23 eyes total1 month postop

2 or more lines lost 0.0%

Figure 4. Change in Snellen lines of

BCVA postoperatively for both myopic and

hyperopic eyes.

actually decrease following LASIK surgery in myopic,

hyperopic and astigmatic eyes. However, the actual IOP

is unchanged because of altered corneal thickness and

curvature and calibration of Goldmann tonometers.

It is difficult to comment on the basis of this study

whether the presence of a Nd:YAG capsulotomy altered

the risk of LASIK surgery. Further studies could look at

whether it would be preferable for LASIK to be

performed before or after a Nd:YAG capsulotomy.

Ayala et al.6 and Pershin and Pashinova26 suggested

that LASIK is a safe procedure when performed 3

months after cataract surgery. They suggested that

performing LASIK sooner could create potential com-

plications related to the cataract incision or IOL insta-

bility. This may be relevant in patients concurrently

using corticosteroids, which may affect wound healing.

In this study, the mean interval between cataract

surgery and LASIK was 12 months (range 2.5 to 46

months).

In summary, the results of this study suggest that

LASIK is a safe, reliable and effective in treating residual

refractive error following cataract surgery. These results

are comparable to those found with virgin eyes and

other studies on pseudophakic eyes.

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Laser in situ keratomileusis for refractive error after cataract surgery