Long-term Refractive Outcomes Research Articles

Outcomes of intrastromal corneal ring segments for treatment of keratoconus: Five-year follow-up analysis

To report the long-term refractive and optical quality outcomes of patients with intrastromal corneal ring segments (ICRS) to treat keratoconus and to analyze the results according to the patients' age. Vissum Instituto Oftalmologico de Alicante, Alicante, Spain. Case series. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, corneal topography, and aberrometry were evaluated before and after ICRS implantation in eyes with keratoconus. The follow-up was 5 years in all cases. The study comprised 51 eyes (35 patients; age range 15 to 56 years). After 6 months, the improvement in the UDVA, CDVA, spherical equivalent, and mean keratometry (K) value was statistically significant (P<.05). Five years postoperatively, these parameters remained unchanged (P=.31). Slight regression (0.97 diopter [D]) was observed in the mean K between 6 months and 5 years; the regression was not statistically significant (P=.39). Anterior corneal aberrometric values decreased; however, the changes were not statistically significant (P ≥.10). Linear regression analysis showed no correlation between the age of the patients and the changes observed in the mean K throughout the follow-up (P>.05, r(2) = 0.001). Intrastromal corneal ring segment implantation in keratoconus patients provided long-term improvement of the refractive and topographic status. There was no correlation between the amount of individual changes in the mean K reading and patient age.

Long-term comparison of laser in situ keratomileusis versus laser surface ablation in corneas thinner than 470 μm

To compare long-term refractive and visual outcomes of laser in situ keratomileusis (LASIK) and laser surface ablation in eyes with corneas thinner than 470 μm. Private clinics, Spain. Comparative case series. The study comprised eyes with myopic error and corneas thinner than 470 μm that had at least 2.9 years of postoperative follow-up between September 2001 and June 2007. The main outcome measures were safety, efficacy, predictability, and complications. The mean central corneal thickness was 462.0 μm (range 440 to 469 μm) in the LASIK group (n = 40) and 458.1 μm (range 420 to 469 μm) in the laser surface ablation group (n = 88). All eyes had normal preoperative topography. In the LASIK group after a mean follow-up of 5.1 years ± 1.5 (SD), the safety index was 1.07, efficacy was 0.99, and predictability (± 1.00 diopter [D]) was 0.93. In the laser surface ablation group after a mean follow-up of 4.8 ± 1.3 years, the safety index was 1.01, efficacy was 0.93, and predictability (± 1.00 D) was 0.92. The mean residual corneal bed thickness in all eyes was 345 ± 25 μm (range 270 to 399 μm). No major complications occurred. The safety index was better in the LASIK group than in the laser surface ablation group. Both techniques were effective, safe, and predictable in eyes with corneas thinner than 470 μm, normal preoperative topography, and a residual corneal bed thickness greater than 250 μm.

Apodized diffractive intraocular lens implantation after laser in situ keratomileusis with or without subsequent excimer laser enhancement

To evaluate the long-term refractive and visual outcomes of apodized diffractive multifocal intraocular lens (IOL) implantation after myopic laser in situ keratomileusis (LASIK) with or without subsequent excimer laser enhancement. University of Texas Southwestern Medical Center at Dallas, Texas, USA. Comparative case series. This study comprised consecutive patients who had implantation of an AcrySof ReSTOR multifocal IOL after previous LASIK. Included were eyes that had refractive surgery enhancement with a Visx Star S4 excimer laser for residual refractive error correction and eyes that had neodymium:YAG (Nd:YAG) capsulotomy. Of the 49 eyes (38 patients), 21 (42.9%) had laser enhancement and 25 (51.0%) had an Nd:YAG capsulotomy. The mean follow-up was 14.2 months ± 7.23 (SD) (range 9 to 29 months). Although the uncorrected distance visual acuity (UDVA) was significantly worse in eyes with enhancement than in those with no enhancement at 1 month and 6 months (P<.05), there was no significant difference in UDVA between the 2 groups at the last follow-up (P>.05). At the last follow-up, 36 (73.5%) of the 49 eyes had a UDVA of 20/25 or better and an uncorrected near visual acuity of Jaeger 1 or better concurrently; 46 eyes (93.9%) were within ±1.00 diopter (D) of emmetropia, and 41 (83.7%) were within ±0.50 D. Apodized diffractive multifocal IOL implantation and excimer laser enhancement in eyes with previous myopic LASIK provided good results.

Long-term refractive outcomes and stability after excimer laser surgery for myopia

To evaluate the long-term refractive outcomes of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for myopia. Centre for Eye Research Australia, Melbourne, Australia. Comparative case series. Preoperative baseline refractions in eyes having PRK, LASIK, or both at 1 multisurgeon center were analyzed from patient databases. Two- to 13-year follow-up data were analyzed and compared with 1-month postoperative visual outcomes. The study evaluated 389 eyes (229 patients). In the PRK group, the mean preoperative spherical equivalent (SE) was -4.05 diopters (D) ± 1.17 (SD) in eyes with low to moderate myopia and -7.97 ± 2.00 D in eyes with high myopia (P = .009) and in the LASIK group, -3.98 ± 1.27 D and -7.64 ± 1.66 D, respectively (P = .008). At the last visit, the mean SE in the PRK group was -0.64 ± 0.83 D in eyes with low to moderate myopia and -1.06 ± 1.74 D in eyes with high myopia (P = .73) and in the LASIK group, -0.33 ± 0.59 D and -0.63 ± 0.90 D, respectively (P = .68). At the end of the study, 45.9% of eyes with low to moderate myopia and 25.0% with high myopia in the PRK group and 64.8% and 37.3%, respectively, in the LASIK group were within ± 0.50 D of the attempted correction. Laser refractive surgery effectively treated all levels of myopia. Refractive stability was achieved within 1 year postoperatively, with LASIK showing better stability than PRK for up to 6 to 9 years.

Seven-year Follow-up of LASIK for Moderate to Severe Myopia

To evaluate long-term refractive outcomes of LASIK for correcting moderate to severe myopia. A long-term (7-year) prospective follow-up study of visual and refractive outcomes in patients who underwent myopic LASIK surgery in 1998 and 1999. Fifty-nine patients (104 eyes) of the original cohort of 75 patients underwent detailed clinical assessment at 1 and 7 years postoperatively. The main outcome measures were predictability, efficacy, safety, and stability. Topography, corneal thickness, and postoperative complications were recorded at 7 years. All patients completed a questionnaire assessing their satisfaction with the procedure. At 7 years postoperatively, 89.4% of eyes were within 0.50 diopters (D) of attempted correction, and 90.4% were within 1.00 D. All eyes had 20/40 or better vision and 94.2% had 20/20 or better. Best spectacle-corrected visual acuity was unchanged or improved in 80.8% of eyes. Eyes did not regress in refraction between 1 and 7 years postoperatively. Complications were rare and patient satisfaction with the surgery was high. LASIK surgery has predictable and stable results in refractive and visual outcomes in correcting moderate to high myopia on long-term follow-up. Refractive stability is maintained over 7 years, with no evidence of progressive late-onset complications.

Long-term results of photorefractive keratectomy for myopia and myopic astigmatism

To assess the long-term refractive outcomes of photorefractive keratectomy in myopia and myopic astigmatism. A retrospective study of 120 photorefractive keratectomy operated eyes with at least four-year follow-up (maximum of 96 months, mean follow-up 55 months). We divided patients into group 1 (G1) spherical equivalent (SE) up to -4.00 diopters (D) and group 2 (G2) SE >-4.00 D. The Summit Apex Plus excimer laser was used for ablation. All eyes were analyzed in terms of uncorrected and best spectacle corrected visual acuity (UCVA/BSCVA) and cycloplegic refraction. Data were analyzed using the Refractive Surgery Consultant Elite database software. G1 with 85 eyes (49 patients) presented mean SE -2.42 D and G2 with 35 eyes (22 patients) and mean SE of -4.45 D. Ninety-four percent of eyes in G1 and 82.9% of G2 were within +/-1.00 D of emmetropia at 4 years. The UCVA was 20/30 or better in 82.0% of G1 eyes and 77.0% of G2 in the last postoperative follow-up. No patient lost more than one line in G2 compared to 13.0% in G1. Eyes that gained one or more lines after 4-year follow-up were 11.9% G1 and 2.9% in G2, respectively. A statistically significant positive correlation was found between achieved versus attempted refractive correction in both groups (r=0.925, p<0.0005). Photorefractive keratectomy was a safe and stable surgical procedure to correct myopic refractive errors, with no significant change in mean postoperative spherical equivalent refraction in the long-term follow-up.

Wavefront-Versus Topography-guided Customized Ablations With the NIDEK EC-5000 CX II in Surface Ablation Treatment: Refractive and Aberrometric Outcomes

To compare the long-term refractive outcomes and changes in higher order wavefront aberrations in patients undergoing photorefractive keratectomy (PRK) with topography-guided (CATz) or wavefront-guided (OPDCAT) ablation algorithm using the NIDEK Advanced Vision Excimer Laser System (NAVEX). A retrospective 12-month follow-up study was conducted of 226 eyes undergoing PRK. The NIDEK EC-5000 CX II excimer laser and Final Fit 1.11 treatment planning software were used. Sixty-eight eyes underwent OPDCAT ablation and 158 eyes underwent CATz ablation. Mean preoperative manifest refractive spherical equivalent (MRSE) was -5.73 +/- 2.03 diopters (D) (range: -11.25 to -2.50 D) in the OPDCAT group and -3.77 +/- 3.78 D (range: -12.50 to -5.75 D) in the CATz group. At 12 months postoperatively, mean MRSE was 0.05 D for the OPDCAT group and plano for the CATz group. Stability was similar in both groups as were visual outcomes. No eyes lost 2 or more lines of BSCVA at 6 months postoperatively or later. Mean ocular wavefront higher order aberrations at 3 months postoperatively were 0.44 +/- 0.17 microm for the OPDCAT group and 0.55 +/- 0.27 microm for the CATz group. Refractive outcomes were equivalent between eyes that underwent PRK with wavefront-guided ablation and those that underwent topography-guided ablation.

Long-Term Refractive and Biometric Outcomes Following Diode Laser Therapy for Retinopathy of Prematurity

To assess the long-term refractive and biometric outcomes of diode laser-treated eyes in threshold retinopathy of prematurity (ROP). Cycloplegic autorefraction and biometry (Zeiss IOLMaster) were performed, at a mean follow-up of 11 years, on 16 laser-treated eyes with threshold ROP and 9 comparison eyes with subthreshold untreated ROP. The laser-treated eyes had a mean spherical equivalent of -2.33 D with a mean astigmatic error of 1.38 D. The comparison eyes had a mean spherical equivalent of +1.07 D with a mean astigmatic error of 0.42 D. This trend toward increased myopia in treated eyes did not achieve statistical significance (p=0.08). The myopia in the laser group appeared to be slowly progressive in nature when compared with earlier refractive data for these patients. The laser-treated eyes had reduced anterior chamber depth (ACD) compared with the subthreshold eyes (p=0.02). When physiologic accommodation was inhibited by cycloplegic drops, the anterior chamber deepened by 0.13 mm in the laser-treated eyes and by 0.06 mm in the comparison eyes. This effect of accommodation on ACD did not differ significantly between the two groups (p=0.23). The laser-treated eyes and the comparison eyes did not differ significantly in terms of axial length, corneal power, corneal diameter, or lens power. However, both groups had steeper corneas, shallower anterior chambers, and shorter axial lengths when compared with historical full-term controls. Myopia in premature infants requiring laser treatment for ROP is associated with a shallowing of the anterior chamber and a steepening of the cornea. Physiological accommodation is not impaired by laser therapy or by severe ROP.