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

Area of Science:

• Ophthalmology
• Vision Science
• Surgical Outcomes

Background:

• Assessing visual recovery after refractive surgery is crucial.
• Contrast sensitivity is a key indicator of visual function.

Purpose of the Study:

• To evaluate contrast sensitivity measurements at various spatial frequencies as an index for visual recovery post-refractive surgery.
• To compare outcomes between photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK).

Main Methods:

• Contrast sensitivity was measured preoperatively and at 1, 3, 6, and 12 months post-surgery.
• Measurements were taken at spatial frequencies of 1.5, 3, 6, 12, and 18 cycles per degree using the Stereo Optical FACT chart.
• The study included 20 patients after PRK and 18 patients after LASIK.

Main Results:

• Photorefractive keratectomy patients showed reduced contrast sensitivity at all frequencies in the first 3 months, recovering by 6 months.
• Laser in situ keratomileusis patients experienced decreased contrast sensitivity at 1 month post-surgery.
• While lower frequencies recovered by 3 months in LASIK patients, higher frequencies remained reduced; all frequencies normalized by 6-12 months.

Conclusions:

• Contrast sensitivity measurements are valuable for assessing visual recovery after refractive surgery.
• Measurements at higher spatial frequencies (6 and 12 c/deg) are particularly useful due to the impact of optical aberrations and defocus.
• These findings aid in understanding and monitoring patient outcomes following PRK and LASIK procedures.