Nd:YAG laser treatment for epithelial ingrowth after laser refractive surgery

Epithelial ingrowth under refractive surgery flaps occurs in primary treatment and in further flap lift. Nd:YAG treatment was first described in 2008. In the only series published to date, 100% of patients treated had topographic and symptomatic improvement. The authors pictorially illustrate two cases of epithelial ingrowth following laser in situ keratomileusis achieving complete symptomatic relief and marked microscopic improvement following Nd:YAG laser treatment.     

Customized ablation algorithm for the treatment of steep central islands after refractive laser surgery

Steep central island (SCI) formation after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) represents a major drawback in the visual rehabilitation of patients after refractive laser surgery. Because of the small size of SCIs, current ablation algorithms are unable to properly calculate an ablation pattern for customized retreatment. We present the use of a new ablation algorithm for the treatment of SCIs that occurred after PRK or LASIK surgery. This algorithm uses a smaller zone of approximation and takes into account the spherical shift induced by removal of the SCI. In all 3 eyes treated, best spectacle-corrected visual acuity increased to 20/16 and remained stable at the 1- and 3-month follow-up, with disappearance of the SCI in corneal topography. This new treatment algorithm may be of benefit to patients experiencing visual side effects due to SCI formation after PRK or LASIK surgery.     

全程飞秒激光屈光手术的研究进展

应用飞秒激光实施全部屈光性切削步骤的全程飞秒激光屈光手术已逐步应用于临床,可用于矫治包括近视、远视、散光和老视在内的所有屈光手术,其矫治效果已得到初步验证.随着飞秒激光技术的不断发展和飞秒激光系统设备的进一步普及,全程飞秒激光屈光手术将具有广阔的应用前景.     

全程飞秒激光屈光手术的研究进展

应用飞秒激光实施全部屈光性切削步骤的全程飞秒激光屈光手术已逐步应用于临床,可用于矫治包括近视、远视、散光和老视在内的所有屈光手术,其矫治效果已得到初步验证.随着飞秒激光技术的不断发展和飞秒激光系统设备的进一步普及,全程飞秒激光屈光手术将具有广阔的应用前景.     

Complications after laser refractive surgery

The laser refractive surgery is very effective method of refractive errors correction. The method is very popular, but serious complications may occur and the visual acuity may decrease. In this article authors show the possible complications after the laser refractive procedures.     

Diode laser treatment of retinopathy of prematurity: anatomical and refractive outcomes

PURPOSE: To examine the anatomical and refractive outcomes of infrared diode laser photocoagulation (DLPC) for the treatment of threshold retinopathy of prematurity (ROP). METHODS: The charts of all consecutive premature neonates with ROP treated by DLPC at our tertiary center from December 1, 1996, to December 31, 2004, were reviewed. RESULTS: The group included 100 neonates (194 eyes) with a mean birth weight +/- SD of 833.9 +/- 250.3 g and a mean gestational age +/- SD of 26 +/- 1.9 weeks. Sixty-two percent of neonates had zone I or posterior zone II ROP. Each eye received a mean +/- SD of 1,740 +/- 990 laser applications, and 21% of eyes received an additional 1 to 2 rows posterior to the ridge. Neonates treated after December 2003 (cutoff date of the Early Treatment of Retinopathy of Prematurity study) underwent a significantly greater number of laser applications (mean +/- SD, 2,286 +/- 1,087) than did neonates treated earlier. Anatomical results of laser treatment were favorable for 179 eyes (92.3%) at a mean follow-up +/- SD of 33.6 +/- 27.2 months. After vitreoretinal surgery, partial or total retinal detachment was documented for 2.5% of patients who received posterior-to-the-ridge laser treatment and 3.8% of patients treated only on the avascular retina. Refractive data were available for 134 eyes: 55.2% had myopia of -5 diopters (31.3%) or greater (23.9%). Strabismus was found in 21 (28.8%) of 73 neonates tested. Gestational age was correlated with corrected age at treatment, zone of ROP, number of laser applications, and spherical equivalent. Snellen visual acuity of 6/12 or more occurred in 17 of 24 patients who complied with testing. CONCLUSION: DLPC is a safe and effective treatment for ROP. Neonates of lower gestational age and birth weight require earlier and more aggressive laser treatment and may have a higher refractive error.     

How to select patients for excimer laser refractive surgery

The first very important step for the refractive surgery is the selection of the patients, because there are situations when the surgery for reducing the diopters can produce complications which are difficult to solve. The investigation of the patients who come for a refractive surgery has many steps and each step has his importance.     

屈光性弱视患者行准分子激光原位角膜磨镶术疗效观察

目的评价准分子激光原位角膜磨镶术(LASIK)治疗屈光性弱视的有效性、安全性和可预测性。方法回顾性分析2003年2月～2005年4月经LASIK治疗的24例(39眼)屈光性弱视病历。术前最佳矫正视力(BCVA)0.25～0.5,平均0.43±0.09。术后随访3～24月,平均12月。结果术后3月,裸眼视力达0.5～0.8及1.0眼分别为64.10%和2.58%,平均0.55±0.19;最佳矫正视力达0.5～0.8及1.0眼分别为61.54%和17.95%,平均0.65±0.22。残余球镜度≤±0.5D及>±0.5～≤±1.0D眼分别为38.46%和17.95%,平均-0.43±1.61D;残余柱镜度≤±0.5D和>±0.5～≤±1.0D眼分别为30.77%和41.03%,平均(-0.75D,0.69D)。结论LASIK可有效矫正屈光性弱视的屈光度,有效提高视力,且具有良好的安全性和可预测性。     

Photorefractive keratectomy: a technique for laser refractive surgery

The excimer laser offers entirely new corneal surgery procedures. In this paper, we describe conditions for one such procedure, photorefractive keratectomy, the direct reshaping of the cornea's central optical zone using tissue ablation with far ultraviolet radiation. We present equations for the required tissue ablation to achieve required refractive corrections. Conditions for beam uniformity are presented and a method of achieving better beam uniformity using beam integration by rotation is demonstrated. The healing of rabbit corneas after area ablation was observed. Five days after treatment, the surface quality of deep cuts was very irregular; the shallow cuts produced more regular results, as predicted by our calculations of beam characteristics.     

Application of ultrashort laser pulses for intrastromal refractive surgery

· Background: Recently, laser systems have become available which generate ultrashort laser pulses with a duration of 100–200 femtoseconds (fs). By generating micro-plasmas inside the corneal stroma with fs pulses, it is possible to achieve a cutting effect inside the tissue while leaving the anterior layers intact. The energy threshold to generate a micro-plasma with fs pulses is some orders of magnitude lower than it is for picosecond or nanosecond pulses. This results in a strong reduction of the thermal and mechanical damage of the surrounding tissue. · Methods: With a titanium:sapphire fs laser system, the cutting effect on corneal tissue from freshly enucleated porcine eye globes was investigated with different pulse energies. The irradiated samples were examined by light and electron microscopy. The laser-induced pressure transients and the laser-induced bubble formation were analysed with a broadband acoustic transducer and by flash photography.  · Results: With fs laser pulses, the extent of thermal and mechanical damage of the adjacent tissue is in the order of 1 μm or below and therefore comparable with the tissue alterations after ArF excimer laser ablation. Using pulse energies of approximately 1–2 μJ and a spot diameter of 5–10 μm, intrastromal cuts can be performed very precisely in order to prepare corneal flaps and lenticules. · Conclusion: Femtosecond photodisruption has the potential to become an attractive tool for intrastromal refractive surgery. Received: 2 February 1999 Revised version received: 7 June 1999 Accepted: 24 June 1999     

Hyperopic laser in situ keratomileusis for refractive accommodative esotropia

PURPOSE: To assess the efficacy of hyperopic laser in situ keratomileusis (LASIK) in creating orthophoria without optical correction in adult patients with refractive accommodative esotropia (RAE). SETTING: Instituto Oftalmológico de Sabadell, Sabadell, Barcelona, Spain. METHODS: This prospective single-center clinical trial studied 9 eyes (18 patients) with RAE having hyperopic LASIK. The mean follow-up was 20 months (range 12 to 24 months). The mean preoperative refraction was +5.01 diopters (D) and the mean deviation angle without optical correction, 36 prism diopters. The intervention was hyperopic LASIK using the Automated Corneal Shaper microkeratome (Bausch & Lomb) and the Apollo broad-beam excimer laser using a 5.5 mm optical zone and an 8.0 mm transition zone; astigmatism was treated by steepening the flattest meridian. RESULTS: All patients achieved orthophoria or the preoperative microtropia without optical correction immediately after surgery. This was maintained throughout the follow-up. Fifty-six percent of all cases were within +/-0.5 D of emmetropia, and 89% were within +/-1.0 D. The uncorrected visual acuity improved significantly (P <.005), especially at near, and the mean best corrected visual acuity (BCVA) was maintained, although 4 eyes (22%) lost 1 line of BCVA. There were no significant complications. CONCLUSIONS: In adult patients with RAE, treatment of the refractive error using hyperopic LASIK was safe and effective and corrected the esodeviation. Further studies in younger patients will help determine the age at which this intervention may be indicated.     

Screening for refractive errors with the Topcon PR2000 Pediatric Refractometer

PURPOSE: The PR2000 (Topcon, Tokyo, Japan) is a photorefractor that has been used in a population study comparing different methods of screening preschool children. The present study was conducted to determine the accuracy of the device in a largely clinical population. METHODS: Two hundred twenty-two children less than 8 years of age were included. All children were examined by an orthoptist using the PR2000 without inducing cycloplegia. All children then underwent retinoscopy with cycloplegia by an examiner who was unaware of the results from the PR2000 examination. RESULTS: The PR2000 gave a numerical reading for 90% of the children's right eyes and the message "Out of range" for a further 5%. The readings underestimated the amount of hypermetropic or astigmatic refractive error found on retinoscopy by an amount proportional to the magnitude of the refractive error. Agreement with retinoscopy for the axis of astigmatism more than 0.75 D was moderately good (intraclass correlation coefficient [ICC] = 0.63). The PR2000 was more useful as a screener, especially for anisometropia for which it was 91% sensitive and 92% specific. The repeatability was good for sphere (ICC = 0.74), less so for astigmatism (ICC = 0.59), and better than the optometrist for anisometropia (ICC = 0.38). The presence of nonrefractive diagnoses and the age of the children examined made little difference in the screening results. CONCLUSIONS: The PR2000 underestimated hypermetropic refractive errors when used without cycloplegia. However, it was at least as good a screening device as other similar instruments, especially when judged by its ability to detect anisometropia and the repeatability of the results.     

準分子激光角膜屈光手術中的個體化切削

准分子激光角膜屈光性手术,随著激光设备的改进及控制系统的逐步完善,已经得到很大的发展。个体化切削,是根据个体的特性及需要去建立、适应或改变准分子激光屈光手术方式的一仪系列方法。许多新的和发展的技术,通过增加视网膜成像的对比度,达至更高的清晰度,以克服以往手术的某些弊端,更大程度地提高视力,减少并发症。屈光手术的未来十年将会有更加美好的前景。     

Cryotherapy and laser treatment for acute retinopathy of prematurity: refractive outcomes, a longitudinal study

BACKGROUND—Infants who require treatment for threshold retinopathy of prematurity are at increased risk of developing refractive errors. Following the introduction of laser treatment for threshold disease, the clinical impression was that the degree of myopia was reduced compared with cryotherapy.
METHODS—A longitudinal study was carried out of refractive error at 3 and 12 months in 19 patients undergoing cryotherapy and 15 patients undergoing laser treatment.
RESULTS—At 3 months the median spherical equivalent refractive error in the right eye was −3.25 dioptres after cryotherapy and +0.25 dioptres after laser therapy (similar results left eye). The median spherical equivalent refractive error in the right eye at 12 months was -5.25 dioptres following cryotherapy and -0.50 dioptres after laser (similar results left eye). There was a statistically significant difference in median spherical refractive error between the therapies at 3 months and 12 months (p<0.05 Wilcoxon rank sum) in both eyes.
CONCLUSION—Laser therapy is associated with lower degrees of myopia during the first year of life, which is clinically significant in terms of visual performance and development.

     

Aberrometer systems in laser refractive surgery

The wavefront sensing device provides a new and objective way of mapping the profile of refraction and of higher order defocus. Higher-order optical errors of the human eye are often responsible for reduced visual acuity, in spite of an optimal spherical or cylindrical refraction. These optical aberrations are of natural origin or can results from operations on the eye, involving optical structures. Nowadays, there are four different methods of wavefront technology available: Concept of "Outgoing" Reflective Aberrometry, Concept of "Retinal Imaging" Aberrometry, Concept of "Ingoing" Adjustable Aberrometry (Spatially Resolved Refractometer), Concept of "Double Pass" Aberrometry. Wavefront analysis is a more sophisticated method of defining aberrations that the surgeon is trying to correct through refractive surgery.     

飞秒激光在基质内屈光手术中的应用

飞秒（10^-15S）激光经证实可以有效的降低切割组织所需的能量并可减少对周围组织的损伤。该激光系统的灵活性使得它不仅可以完成传统的角膜基质内手术,而且可以进行新的角膜屈光手术。本研究就其机制、手术方法和过程、并发症等方面做一综述。     

准分子激光屈光手术上皮下雾状混浊的发生机制

准分子激光屈光矫正手术已经广泛开展,而上皮下雾状混浊(haze)作为其术后主要的并发症之一却一直困扰着眼科医师。研究表明,haze的发生受到许多因素影响,包括手术方式、术后的创伤愈合过程以及个体差异等,其中角膜上皮基底膜在haze形成中的作用为近几年研究的热点。