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J Refract Surg. 2001 Nov-Dec;17(6):646-51.

Choice of spatial frequency for contrast sensitivity evaluation after corneal refractive surgery.

Author information

1
Unitat d'Optometria i Ciències de la Visió, Universitat de Valencia, Spain. roberto.montes@uv.es

Abstract

PURPOSE:

To study the utility of measurements of contrast sensitivity at different spatial frequencies as an index of visual recovery following refractive surgery.

METHODS:

Contrast sensitivity at 1.5, 3, 6, 12, and 18 c/deg was measured with the Stereo Optical FACT chart in 20 patients after photorefractive keratectomy (PRK) using the Nidek EC-5000 excimer laser system, and in 18 patients following laser in situ keratomileusis (LASIK). Contrast sensitivity was measured preoperatively and 1, 3, 6, and 12 months after surgery.

RESULTS:

Results showed a statistically significant reduction (P<.01) in contrast sensitivity at all spatial frequencies in PRK patients during the first and third month, but contrast sensitivity recovered to preoperative values by 6 months after surgery (P>.1). In LASIK patients, decreased contrast sensitivity values 1 month after surgery were also obtained at all spatial frequencies. After 3 months, contrast sensitivity at 1.5 and 3 c/deg had recovered and did not differ significantly from preoperative values (P>.1), although contrast sensitivity at other frequencies remained reduced (P<.01). At 6 and 12 months, contrast sensitivity at all spatial frequencies did not differ from that obtained preoperatively (P>.1).

CONCLUSIONS:

Contrast sensitivity measurements at 6 and 12 c/deg appear to be most useful in the assessment of patients who have undergone laser refractive surgery because defocus and optical aberrations primarily affect the higher spatial frequencies.

PMID:
11758982
[Indexed for MEDLINE]

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