Comparison of wavefront-guided photorefractive keratectomy and foldable iris-fixated phakic intraocular lens implantation for low to moderate myopia

Reasons for not performing surface ablation refractive surgery in Saudi population

PURPOSE:

The primary goal of this study is to analyze the reasons why refractive surgery was not performed for candidates who requested the procedure among single eye-clinic visitors in Saudi Arabia. Secondarily, we aimed to determine the corneal parameters that are characteristic of Saudi population and to figure out the relationship between the magnitude of central corneal thickness and the degree of myopia.

METHODS:

A retrospective data was collected for all patients who presented to a single-surgeon eye clinic at King Abdul Aziz Medical City-National Guard, Saudi Arabia, seeking refractive surgery between January 2010 and December 2015.

RESULTS:

Unstable refraction (21.78%) followed by amblyopia with unrealistic expectations (18.75%) and high myopia (15.62%) were the most common reasons not to proceed with refractive surgery in the included sample. The mean central corneal thickness for all patients included in this study was (538 μm ± 32.6). We found no significant relationship between central corneal thickness and the degree of myopia OD [rs(178) = −0.017, P = 0.823] and OS [rs(182) = 0.016, P = 0.831] for right and left eyes, respectively.

CONCLUSION:

Unstable refraction followed by amblyopia with unrealistic expectations and high myopia were the leading causes not to perform refractive surgery in this study. No significant relationship can be figured out between central corneal thickness and the degree of myopia.

Phakic Intraocular Lenses and their Special Indications

Phakic intraocular lenses revolutionize refractive surgery and continue to serve as an excellent option for vision correction in patients who are not ideal candidates for laser vision correction. This article will review special indications of phakic intraocular lenses in the clinical practice.

Wavefront-Guided Photorefractive Keratectomy with the Use of a New Hartmann-Shack Aberrometer in Patients with Myopia and Compound Myopic Astigmatism

Purpose. To assess refractive and visual outcomes and patient satisfaction of wavefront-guided photorefractive keratectomy (PRK) in eyes with myopia and compound myopic astigmatism, with the ablation profile derived from a new Hartmann-Shack aberrometer. Methods. In this retrospective study, 662 eyes that underwent wavefront-guided PRK with a treatment profile derived from a new generation Hartmann-Shack aberrometer (iDesign aberrometer, Abbott Medical Optics, Inc., Santa Ana, CA) were analyzed. The preoperative manifest sphere ranged from −0.25 to −10.75 D, and preoperative manifest cylinder was between 0.00 and −5.25 D. Refractive and visual outcomes, vector analysis of the change in refractive cylinder, and patient satisfaction were evaluated. Results. At 3 months, 91.1% of eyes had manifest spherical equivalent within 0.50 D. The percentage of eyes achieving uncorrected distance visual acuity 20/20 or better was 89.4% monocularly and 96.5% binocularly. The mean correction ratio of refractive cylinder was 1.02 ± 0.43, and the mean error of angle was 0.00 ± 14.86° at 3 months postoperatively. Self-reported scores for optical side effects, such as starburst, glare, halo, ghosting, and double vision, were low. Conclusion. The use of a new Hartmann-Shack aberrometer for wavefront-guided photorefractive keratectomy resulted in high predictability, efficacy, and patient satisfaction.

Screening of refractive surgery candidates for LASIK and PRK

PURPOSE

The aim of this study was to evaluate exclusion criteria in screening patients for refractive surgery.

METHODS

Patients screened for initial refractive surgery by a single surgeon at the Cole Eye Institute (Cleveland Clinic) between 2007 and 2012 were reviewed. Exclusion criteria for patients who were not offered refractive surgery based on history and/or examination parameters were analyzed.

RESULTS

A total of 1067 refractive candidates were enrolled in the study. Five hundred nineteen (48.6%) were male and 548 (51.4%) were female with a mean age of 39 ± 12 (range, 17-78) years. Refractive surgery was performed in 657 (61.6%) patients, and photorefractive keratectomy was considered the best option for 106 (9.9%) patients. Four hundred ten (38.4%) of all screened patients did not have refractive surgery, and 134 of these patients (12.6%) were considered to have contraindications for laser in situ keratomileusis and photorefractive keratectomy. Among the excluded patients, 69 (51.5%) were male and 65 (48.5%) were female with a mean age of 40 ± 14 (range, 18-78) years. Abnormal corneal topography (34.3%) and low or insufficient corneal thickness (23.1%) were the most common reasons for exclusion. High myopia (10.5%) and (insipient or definite) cataract (9.7%) were also common reasons for exclusion. Other common factors for exclusion were high hyperopia (3.7%), need to wear reading glasses after surgery (3.7%), and severe dry eye unresponsive to treatment (3.7%).

CONCLUSIONS

Abnormal corneal topography and low, or insufficient, corneal thickness remain the most common exclusion factors for corneal refractive surgery. Factors such as cataract, too high of correction, and severe dry eye are also common reasons for exclusion of patients.

Comparison of the visual outcomes between PRK-MMC and phakic IOL implantation in high myopic patients

PURPOSE

To compare the visual outcomes between PRK-MMC and phakic IOL in patients with more than 8 diopter (D) of myopia.

METHODS

This comparative study was performed on 23 eyes under treatment with Artiflex (group A) and 23 eyes under treatment with PRK-MMC (group B). Artiflex phakic IOL (Ophtec BV) was used in group A, and the VISX STAR S4 Excimer Laser (Abbott) was used for PRK-MMC in group B.

RESULTS

The safety index was 1.11 ± 0.23 and 1.05 ± 0.25 (P = 0.100) and the efficacy index was 1.02 ± 0.11 and 0.98 ± 0.10 (P = 0.266) in group A and B, respectively. At 1 year after surgery, the manifest refraction spherical equivalent was -0.17 ± 1.18 and -0.25 ± 0.18 D in group A and B, respectively (P = 0.471). Mesopic CS showed no significant difference between the two groups in any spatial frequency. Total coma was 0.24 ± 0.17 and 0.67 ± 0.40 μm (P < 0.001), spherical aberration was -0.11 ± 0.11 and 0.41 ± 0.18 μm (P < 0.001), and RMS HOAT was 0.50 ± 0.20 and 0.96 ± 0.45 μm (P<0.001) in group A and B, respectively.

CONCLUSION

Phakic IOL implantation was better than PRK-MMC in the correction of high myopia in terms of visual quality, but the two methods had no difference with regard to visual acuity. Therefore, PRK-MMC can be used when the anterior chamber depth is a limiting factor in the implantation of phakic IOLs.