Journal of refractive surgery (Thorofare, N.J. : 1995) · 2013
Non-penetrating femtosecond laser intrastromal astigmatic keratotomy in patients with mixed astigmatism after previous refractive surgery.
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Venter Jan, Blumenfeld Rodney, Schallhorn Steve, Pelouskova Martina
Аннотация
PURPOSE: To report the outcomes of the correction of mixed astigmatism with non-penetrating femtosecond laser intrastromal astigmatic keratotomy in patients with previous refractive surgery.
METHODS: One hundred twelve eyes that had low mixed astigmatism after excimer laser surgery, refractive lens exchange, or phakic intraocular lens implantation underwent intrastromal astigmatic keratotomy using paired symmetrical non-penetrating intrastromal arcuate keratotomies created 60 μm from the surface to 80% depth at 7 mm diameter. Outcome measures included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), subjective refraction, and keratometry. A coupling ratio was calculated to assess the change in spherical equivalent. Average follow-up was 7.6 ± 2.9 months. Patients were divided into two groups: no excimer laser corneal ablation and previous excimer laser surgery. Preoperative and postoperative data were compared between groups and analyses were performed on the whole group of eyes.
RESULTS: Overall, the mean UDVA improved significantly from 0.18 ± 0.14 to 0.02 ± 0.12 logMAR (6/9 to ≈6/6 Snellen) (P < .01). The mean absolute subjective cylinder decreased significantly from 1.20 ± 0.47 diopters (D) preoperatively to 0.55 ± 0.40 D postoperatively (P < .01). Subjective sphere decreased significantly from +0.61 ± 0.33 to +0.17 ± 0.36 D (P < 0.01). The mean CDVA was -0.03 ± 0.08 logMAR (≈ 6/6 Snellen) preoperatively and -0.05 ± 0.09 logMAR (≈ 6/5 Snellen) postoperatively (P = .06). The coupling ratio was 0.92 ± 0.45. There was no statistically significant difference in the preoperative and postoperative sphere, cylinder, UDVA, CDVA, and coupling ratio between groups. No surgical complications occurred.
CONCLUSIONS: Femtosecond laser intrastromal astigmatic keratotomy was effective at reducing refractive error in patients where other surgical options were exhausted. Predictability and efficacy could be improved with nomogram refinement.
METHODS: One hundred twelve eyes that had low mixed astigmatism after excimer laser surgery, refractive lens exchange, or phakic intraocular lens implantation underwent intrastromal astigmatic keratotomy using paired symmetrical non-penetrating intrastromal arcuate keratotomies created 60 μm from the surface to 80% depth at 7 mm diameter. Outcome measures included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), subjective refraction, and keratometry. A coupling ratio was calculated to assess the change in spherical equivalent. Average follow-up was 7.6 ± 2.9 months. Patients were divided into two groups: no excimer laser corneal ablation and previous excimer laser surgery. Preoperative and postoperative data were compared between groups and analyses were performed on the whole group of eyes.
RESULTS: Overall, the mean UDVA improved significantly from 0.18 ± 0.14 to 0.02 ± 0.12 logMAR (6/9 to ≈6/6 Snellen) (P < .01). The mean absolute subjective cylinder decreased significantly from 1.20 ± 0.47 diopters (D) preoperatively to 0.55 ± 0.40 D postoperatively (P < .01). Subjective sphere decreased significantly from +0.61 ± 0.33 to +0.17 ± 0.36 D (P < 0.01). The mean CDVA was -0.03 ± 0.08 logMAR (≈ 6/6 Snellen) preoperatively and -0.05 ± 0.09 logMAR (≈ 6/5 Snellen) postoperatively (P = .06). The coupling ratio was 0.92 ± 0.45. There was no statistically significant difference in the preoperative and postoperative sphere, cylinder, UDVA, CDVA, and coupling ratio between groups. No surgical complications occurred.
CONCLUSIONS: Femtosecond laser intrastromal astigmatic keratotomy was effective at reducing refractive error in patients where other surgical options were exhausted. Predictability and efficacy could be improved with nomogram refinement.