Is Photorefractive Keratectomy the Laser Vision Correction of

Choice?

Dr. JoAnn Chang

Dr. Mark Mifflin

Dr. Majid Moshirfar

The authors have no financial interest in the

content of this presentation.

• To report the increasing utilization of PRK by multiple refractive surgeons at a single academic institution

Purpose

Methods

• A retrospective case review of 6675 refractive surgeries at the John A. Moran Eye Center from January 1, 2002 to July 31, 2008 was performed.

• The change in proportion of PRK to LASIK cases over time was analyzed.

Methods

• Analysis of 2008 PRK patients (n=166)

– Manifest refraction spherical equivalent (MRSE)

– Pachymetry at the thinnest location (CCT)

– Topographic symmetry patterns

– Reasons for PRK

Results• Excluding all other refractive procedures, 5836

cases were either PRK or LASIK.• Rate of PRK per year, as a percentage of LASIK

volume – 2002 – 8%– 2003 – 9% – 2004 – 17% – 2005 – 25% – 2006 – 45% – 2007 – 54%– 2008 – 115% *PRK exceeded LASIK in the first half of

2008

Results

• Graphically, the increasing % PRK is seen below

LASIK VS. PRK at the Moran Eye Center

0100200300400500600700800900

2001Aug-Dec

2002 2003 2004 2005 2006 2007 2008Jan-Jul

Year

# E

yes

LASIK

PRK

Results

• PRK patients (Jan – Jul 2008, n=166)– Average age 36 years (20 to 62)

– Mean MRSE -4.59 D (+1.75 to -10.00)

– Average CCT 530 µm (425 to 650)

– Custom wavefront treatment was performed in 56% of patients.

Results – 2008 PRK Patients

• Reasons for choice of PRK over LASIK– Topographic

• Thin CCT• Asymmetry• Step curvature

– Surface Disease• Dry eye Syndrome• Other (ABMD, scar)

– Surgeon recommendation– Patient preference

Results• Separate analysis comparing the preoperative

and postoperative data from a sampling of 385 LASIK and 402 PRK eyes (2008) was also performed

PRK (n = 402) LASIK (n = 385)

Age (years) 35 ± 10 36 ± 10

Sphere (D) -4.38 ± 2.1 -3.89 ± 2.2

Cylinder (D) 0.83 ± 0.90 0.92 ± 0.90

CCT (µm) 535 ± 38 558 ± 34

Table 1: Comparison of preoperative data from sampling of PRK and LASIK patients

PRK = photorefractive keratectomy; D = diopters;LASIK = laser-assisted in situ keratomileusis;CCT = central cornea thickness

Results

• The outcomes between LASIK and PRK patients are similar as seen here at 12 months.

Comparison on Visual Outcomes of 402 PRK vs. 385 LASIK patients in 2008

-5

-4

-3

-2

-1

0

1

Preop 1 Mo 3 Mo 6 Mo 9 Mo 12 Mo

Time

Sp

her

ical

Eq

uiv

alen

t (D

)

PRK

LASIK

Conclusion

• Photorefractive Keratectomy has steadily increased in frequency in our academic center, surpassing LASIK in 2008.

• Advances in laser technology, improved techniques for surface ablation and patient management, and safety considerations have resulted in increased acceptance of PRK by surgeons and patients in our practice.