The state of refraction in children with ophthalmic diseases of the disabling form

The refraction condition was analyzed in 670 impaired-vision schoolchildren with various ophthalmic pathologies. Refraction defects were diagnosed in 98.9% of cases. Myopic refraction was detected in 48.9% of cases, while hypermetropic refraction was found in 50.0% of cases. Astigmatism was observed in 97.8% of cases; in 38.6%, it exceeded 2.0 diopters, which was mainly encountered at the retinopathy of prematurely newborns, albinism and congenital myopia. Compound astigmatism was detected in 83.5% of cases and mixed astigmatism was present in 8.3% of cases; the latter was more frequent diagnosed in persons with albinism and with abnormal development of the eyeball. Regular astigmatism was found in 78 > 8 of the examinees, inversed astigmatism was found in 11.0% of cases and squint astigmatism was detected in 10.2% of cases, the last mentioned type was more often found at the retinopathy of prematurely newborns, abnormal development of the eyes and at postoperative aphakia. Anisometry exceeded 2.0 diopters in 21.8% of cases; a high anisometry was more frequent at the retinopathy of prematurely newborns, congenital myopia and aphakia. 7.6% of schoolchildren lacked the subject-vision in the second eye. Nystagmus was registered in 46.4% of children. The spectacle vision correction was found to be effective in 94.8% of cases, however, the severe refractive defects belong to the unfavorable factors for an optimal spectacle vision correction or for creating a full-value binocular vision image. Groups were specified, which are more favorable and more complicated for the spectacle correction of impaired vision. The use of modern contact lenses in the correction of high-degree ametropia, astygmatigmus and anisometry can be of an effective assistance in expanding the indications for a rational optic correction in impaired-vision children.     

Management of postkeratoplasty astigmatism.

Many factors have led to the improved success rate for clear corneal grafts after penetrating keratoplasty. Unfortunately, postoperative corneal astigmatism commonly occurs and can produce significant visual impairment. Astigmatic correction may include spectacle correction or contact lenses, but if this fails, then surgical options are considered. Refractive surgical techniques such as suture removal or adjustment, relaxing incisions, wedge resections, and photorefractive keratectomy or laser in situ keratomileusis can dramatically reduce postoperative astigmatism after penetrating keratoplasty and lead to improved, functional vision. However, significant variability between results in individual patients can occur. So although general guidelines are useful, it is important to individualize and modify the planned surgery based on qualitative keratoscopy and corneal topography for the initial and subsequent astigmatic corrections.     

Bilateral Implantation of Scleral-Fixated Cionni Endocapsular Rings and Toric Intraocular Lenses in a Pediatric Patient with Marfan's Syndrome

The management of ectopia lentis in Marfan''s syndrome is challenging. Multiple disease-associated factors conspire to deprive these patients of adequate vision. While optical correction with glasses and contact lenses is usually advocated early on, the irregular astigmatism and even partial aphakia that accompanies advanced cases generally warrant surgical intervention. Several surgical strategies have been devised to manage these challenging cases, including the combination of endocapsular or pars plana lensectomy and iris or scleral fixation of the intraocular lens (IOL) or IOL-bag complex. All of the reported cases have been implanted with IOLs that correct for myopia only. With toric lenses, it is now possible to correct for corneal astigmatism in these patients as well, provided that the capsular bag is maintained and can be properly centered. We report the combination of scleral-fixated Cionni endocapsular rings and toric IOLs in a pediatric patient with bilateral ectopia lentis secondary to Marfan''s syndrome.Key words: Ectopia lentis, Marfan''s syndrome, Toric intraocular lens, Cionni endocapsular ring     

白内障术中矫正角膜散光的研究进展

散光矫正是屈光性白内障手术的必然要求,术中散光矫正问题日益受到重视。术前对角膜的屈光状态充分评估,科学合理设计手术切口,选择适宜手术方式,矫正术前存在的角膜散光,是解决白内障术后因散光导致视觉质量不佳的有效方法。目前白内障术中矫正散光的方法主要有角膜松解术和散光矫正型人工晶状体(Toric IOL)植入术。本文就白内障术中联合矫正角膜散光相关研究进行综述。     

散光矫正手术及最新进展

目的：在最近的十年中，像近视眼手术一样，散光治疗的发展速度很快。本文就散光性角膜切开术的（Astigmatic Keratotomy AK)现代作用及近年出现的准分子激光表面角膜散光术（Photoastigmatic Refractive Keratectomy,PARK)、准分子激光原位角膜磨镶术（Laser in Situ Keratomileusis LASIK）、激光角膜热成形术（Laser thermokeratoplasty,LTK)等手术予以综述。并涉及更新的手术方法如眼眼内晶状体植入（IOLs)等。而个体化切削和波前引导等新技术的引用会使散光手术达到理想视觉效果。     

Surgical approaches to correct corneal astigmatism at time of cataract surgery: a mini-review

Among refractive errors, astigmatism is the most common optical aberration, where refraction changes in different meridians of the eye. It causes blurred vision at any distance and includes corneal, lenticular, and retinal astigmatism. Cataract surgery used to cause a progressive increase in the pre-exisiting corneal astigmatism because of creating a surgically induced astigmatism, for example, a large size surgery incision. The development of surgical techniques during last decades has made cataract surgery interchange to treat preoperative corneal astigmatism at time of surgery. Nowadays, three surgical approaches can be used. By placing a sutureless clear corneal incision on the steep meridian of the cornea, a preoperative corneal astigmatism less than 1.0 D can be corrected. Single or paired peripheral corneal relaxing incisions (PCRIs) provide 1.0-3.0 D corneal astigmatism correction. PCRIs are typically used for treating 1.0-1.5 D of regular corneal astigmatism, if more than 2.0 D, the risk of overcorrection and irregular astigmatism is increased. When toric intraocular lenses (IOLs) are unavailable in markets, PCRIs are still a reasonable option for patients with up to 3.0 D of pre-existing corneal astigmatism. Toric IOLs implantation can correct 1.0-4.5 D of corneal astigmatism. Several IOLs are approved to correct a high degree of corneal astigmatism with cylinder power up to 12.0 D. These approaches can be used alone or in combination.     

角膜后表面散光对散光型人工晶状体计算的重要性

随着白内障手术由复明性向屈光性转变,对角膜的散光矫正显得越来越重要。而角膜散光不仅仅应该关注角膜前表面的散光数据,更应该考虑角膜后表面的散光,否则对散光人工晶状体植入矫正角膜散光可能出现不同程度的术后屈光误差。角膜后表面散光均值约为0.37 D,且多数情况下会产生逆规散光的效果,因此在进行散光型人工晶状体计算时应考虑到这一特点,进一步防止术后欠矫或过矫的发生。     

Alternatives to toric contact lens fitting—for regular and irregular astigmatism

Although toric contact lenses have improved in design and development and their use is increasing, further consideration should be given to the alternative methods of astigmatism correction by contact lenses. Much can still be achieved by non-toric lens, both for a wide range of astigmatism and for ease of supply. A number of these alternatives are examined, their advantages and disadvantages reappraised, and the merits of lens correction compared with surgical methods considered.     

Radial keratotomy complications

In a new surgical procedure, adverse reactions or complications may surface without most ophthalmic surgeons experiencing them or being aware of them. Even those with a large series of cases may never see certain problems. Through a collaborative effort with over 200 radial keratotomy surgeons totaling 63,000 cases nearly every significant complication has been documented. This study of radial keratotomy complications includes the number of patients and percentage of the total of the following: intraoperative occurrences which generally do not affect vision, which include microperforations and macroperforations; postoperative changes which do not affect vision: limbal "peeking" and star pattern with light; transient occurrences which tend to resolve with time: ptosis, recurrent erosions, corneal ulcer, microwound abscess, delayed wound healing, inferior rectus palsy, glare or fluctuating vision after six months, iritis, and stromal keratitis; postoperative changes which can affect vision (correctible): overcorrection more than 1.5 diopters, marked undercorrection more than -2.00 diopters, irregular astigmatism, neovascularization after soft-contact-lens wear, and best-corrected acuity decreased usually only one line; and postoperative changes which can affect vision (uncorrectible): retrobulbar hemorrhage and endophthalmitis, loss of the eye, herpes keratitis, and cataract formation.     

Videokeratography in contact lens practice

Irregular corneal astigmatism can severely reduce visual acuity. In such cases, functional vision is often restored with contact lenses, but not with spectacles or refractive surgery. Contact lens fitting is frequently more difficult in eyes with irregular astigmatism than it is in eyes with regular astigmatism. Evaluation of irregular astigmatism is important so that contact lens practitioners can use contact lenses to the patient's best advantage. Manual and automated keratometers, which are widely used in contact lens practice, can detect irregular astigmatism, but do not provide sufficient information to determine the type and extent of the topographic abnormality. Modern videokerato-scopes provide large area analysis of corneal topography to detect irregular astigmatism and to aid contact lens fitting.     

Corneal topography in cataract surgery

Keratometry and videokeratography are the most important means of evaluating induced corneal changes after surgery and have comparable sensitivities in the paracentral region of the cornea. When cataract surgery is planned, corneal topography can be used preoperatively in the calculation of IOL power, particularly in difficult cases, such as in patients who have undergone corneal refractive surgery or penetrating keratoplasty. A study published in the past year suggests that the mean power in ring 3 of the Tomey TMS-1 videokeratoscope (Cambridge, MA) appears to give the most accurate estimate of corneal power for the calculation of IOL power after radial keratotomy. In the case of PRK, traditional methods of determining the corneal power can lead to great amounts of anisometropia. Further research is needed to develop more accurate methods of calculating IOL power after PRK. Videokeratography can also be used before cataract surgery in planning the location and size of the incision. In general, smaller temporal incisions result in less astigmatism than do larger superior incisions. Postoperatively, videokeratography can be used to detect tight sutures, torsion of the wound, internal wound gape, and irregular astigmatism, as well as to guide suture removal or in cases where best-corrected visual acuity is not adequate and there are no other obvious causes for poor vision to determine if corneal irregularities are present.     

电脑验光仪、角膜曲率计、检影验光测量散光的比较

目的:比较电脑验光仪、角膜曲率计和检影验光检查角膜散光三种方法。方法:采用电脑验光仪、角膜曲率、检影验光三种方法对屈光不正患者169例(338眼),进行检查。结果:本组病例中散光度数以3.50D以下为主,顺规性散光125例(250眼),占74.5%。逆规性散光44例(88眼),占25.5%。三者测出散光轴位比较,散光轴位基本相同,其中以电脑验光最准,差异无显著性(P>0.05)。三者测出散光度数比较,差异有非常显著性(P<0.01)。结论:电脑验光、检影验光对散光轴位和度数测量各有优点、验光中相辅相成避免误差,是一种好的工作方法。     

Trapezoidal keratotomy: a contact lens case

Incisional refractive surgery for the correction of astigmatism, introduced by Ruiz in the 1980s, was a milestone for the now more sophisticated refractive surgery procedures. Patients who underwent this pioneering technique often suffered from numerous complications, eventually resulting in the need for vision correction with either further surgery or rigid contact lenses. A contact lens case report of one patient, whose procedure resulted in highly irregular and astigmatic corneas, is presented along with an overview of the original Ruiz astigmatic keratotomy technique. This case—as most post-surgical contact lens fitting cases are—was challenging, but resulted in remarkable improvement in the vision quality and lens comfort of the patient.     

Our initial experience with the surgical correction of astigmatism by sectorial keratorrhaphy

The authors analyze the first experience with surgical correction of corneal astigmatism by sectorial keratorrhaphy (SKR). The operation consists in sewing an intralamellar nylon (9.00) suture perpendicular to poorly refracting meridian of the cornea. The mechanism of alteration of the corneal curvature resultant from SKR is similar to that in the known wedge-shaped resection of the cornea. The technique of surgery has been mastered in experiments with 12 isolated cadaver eyes. Morphologic studies of 16 eyes of 8 rabbits have lead the authors to a conclusion that prolonged presence of monofilament sutures in the corneal stroma induces the minimal changes in the adjacent tissues, these changes not augmenting over the follow-up period. 15 operations were performed in clinic, the follow-up periods were 4 to 14 mos. The data of the subjective examination of the refraction indicate that corneal astigmatism has reduced by 0.5 to 5.5 diopters, by 2.0-4.0 diopters in the majority of cases. The results evidence that SKR may be used as a method of choice for the surgical correction of hypermetropic or mixed astigmatism.     

Difficult lens power calculations

PURPOSE OF REVIEW: Although cataract extraction seems to be feasible without major technical obstacles, the surgical technique has changed completely, and patients are no longer satisfied with good spectacle-corrected vision but anticipate complete visual rehabilitation after cataract surgery, without correction. To fulfill this desire, toric or accommodative intraocular lenses are of increasing popularity, and the intraocular lens power calculation after keratorefractive surgery has been improved. RECENT FINDINGS: In this review article, we provide an overview of different mathematical strategies of calculating the intraocular lens power with standard formulas and with new algorithms, such as paraxial or numeric ray-tracing. These enhanced techniques may improve the validity of lens power calculation due to reduction of the prediction error, especially in cases with high or excessive corneal astigmatism and after refractive laser surgery. Furthermore, a new calculation scheme for the determination of bitoric eikonic intraocular lenses allows a distortion-free imaging in astigmatic eyes. The biometric determinants for the different formulas and calculation schemes are discussed in detail. SUMMARY: In difficult cases, standard calculation schemes are overemployed and new mathematical algorithms are necessary to adequately address these problems. Ray-tracing algorithms and other complex mathematical computation schemes are of increasing interest and will more and more replace conventional calculation formulas for determination of intraocular lens power.     

Astigmatism and toric intraocular lenses

The article reviews some of the basic optics of astigmatism and the correction of astigmatism with cylindric lenses. A simple model of the conoid of Sturm is demonstrated, and an ideal position for the conoid is postulated. The orientation of the conoid shows that leaving patients with some simple myopic "against-the-rule" astigmatism is beneficial to near work, whereas "with-the-rule" astigmatism is beneficial for distant viewing. Surgeons should be less aggressive with patients with with-the-rule and against-the-rule astigmatism and more aggressive with oblique astigmatism. The toric intraocular lens (IOL) should be positioned on axis or, if slightly off axis, err on the side away from the vertical or horizontal meridian so that the resultant cylinder is more vertical or horizontal. Clinically significant rotation of the toric IOL occurs in a few cases, but these can be easily rerotated. Rerotation should be done between the first and second weeks after primary implantation.     

Treating astigmatism at the time of cataract surgery.

Correcting astigmatism at the time of cataract surgery can be accomplished either by incisional techniques, such as use of a cataract incision for flattening or astigmatic keratotomy, or by implanting a toric intraocular lens. Both methods can reduce mild to moderate astigmatism. For correcting larger amounts of astigmatism, a combination of techniques can produce greater correction. New methods of analyzing the change induced by surgery provide a more complete understanding of the astigmatic change.     

Functional outcomes and patient satisfaction after laser in situ keratomileusis for correction of myopia

PURPOSE: To determine subjective patient satisfaction and self-perceived quality of vision after laser in situ keratomileusis (LASIK) to correct myopia and myopic astigmatism. SETTING: Department of Ophthalmology, Academic Hospital Maastricht, Maastricht, The Netherlands. METHODS: A validated questionnaire consisting of 66 items was self-administered by 142 consecutive patients. Seven scales covering a specific aspect of quality of vision were formulated. Aspects included global satisfaction, quality of uncorrected and corrected vision, quality of night vision, glare, daytime driving, and night driving. Main outcome measures were responses to individual questions and scale scores, and correlations with clinical parameters including refractive outcome, uncorrected visual acuity, best corrected visual acuity, ablation depth, and scotopic pupil-optical zone disparity were obtained. RESULTS: The mean score for the overall satisfaction was 4.1 +/- 0.71 (SD) (scale 0 to 5.0). A total of 92.2% of patients were satisfied or very satisfied with their surgery, 93.6% considered their main goal of surgery achieved, and 92.3% would choose to have LASIK surgery again. Satisfaction with uncorrected vision was 3.03 +/- 0.71. The mean score for glare was 3.0 +/- 0.9. At night, glare from lights was believed to be more important than before surgery by 47.2%. Glare from oncoming car headlights after surgery was reported by 58.4% and was believed to be more bothersome for night driving than before surgery by 52.8%. Night driving was rated more difficult than before surgery by 39.4%, whereas 59.3% had less difficulty driving at night. There was a significant correlation between the uncorrected vision score and the postoperative spherical equivalent (r = 0.245) and postoperative astigmatism (r = 0.265). There was no correlation between the glare or night vision scores and the degree of correction, the amount of ablation depth, or the disparity between the scotopic pupil and the optical zone. CONCLUSIONS: Self-perceived uncorrected vision after LASIK surgery for the correction of myopia and myopic astigmatism appears to be very good and is related to the postoperative residual error. Although the majority of patients postoperatively experienced glare, particularly with driving at night, this was not related to the pupil-optical zone disparity or degree of correction.     

白内障手术同时矫正术前散光的研究进展

随着白内障手术的日臻完美,术后残留散光逐渐成为影响患者获得理想屈光状态的主要原因之一.目前,散光矫正已成为屈光性白内障手术的重要内容.白内障手术同时矫正散光的方法主要包括:利用手术切口或散光角膜切开术矫正散光,选择植入散光型人工晶状体.这些方法各有其适应证及优缺点.术前散光检测及散光矫正方案设计是该手术的核心内容.散光矫正效果受多种因素影响.本文就以上内容对白内障手术同时矫正术前散光方面的研究进展作一综述.(中华眼科杂志,2011,47:573-576)

Abstract：

With the increasing progress of cataract surgery, the postoperative residual astigmatism has become one of the factors that influences the desirable refractive outcome for patient. Correction of astigmatism has become an important aspect of refractive cataract surgery. There are several options for correcting astigmatism at the time of cataract surgery, which include using the cataract incision or astigmatic keratotomy to counteract pre-existing astigmatism, or using a toric intraocular lens (Toric IOL). All of these choices have their operational indications, inherent advantages and disadvantages. The central concern of astigmatism surgery lies in the preoperative measurement and subsequent surgical planning for its correction. And the correction effect will be influenced by various factors. This paper reviews the recent progress in treating astigmatism at the time of cataract surgery based on the above points.     

Corneal topography in cataract surgery

Keratometry and corneal topography remain the most important means of evaluating induced corneal changes after surgery and have comparable sensitivities in the paracentral region of the cornea. However, keratometry gives no information about the peripheral cornea or about asymmetry of the cornea. Videokeratography should be performed after cataract surgery in cases in which best-corrected visual acuity is not adequate and there are no other obvious causes for poor vision to determine whether corneal irregularities are present. The recent literature on corneal topographic evaluation of induced astigmatism after cataract surgery suggests that in general, smaller, temporal incisions result in less astigmatism. Preoperatively, corneal topography can be used in the calculation of intraocular lens power as well as incision planning. Postoperatively, it can be used to detect tight sutures, torsion of the wound, internal wound gape, and irregular astigmatism, as well as to guide suture removal. In the future, corneal topography will become increasingly important in the determination of intraocular lens power in difficult cases such as patients undergoing combined cataract extraction and penetrating keratoplasty as well as patients with a history of radial keratotomy or photorefractive surgery.