Validity of percentage tissue altered as a screening formula for post laser-assisted in-situ keratomileusis ectasia in Indian eyes

Purpose:To calculate a modified percentage tissue altered (mPTA) in post laser-assisted in-situ keratomileusis (LASIK) eyes and to validate its role as an independent factor to evaluate ectasia in the Indian population.Methods:A total of 333 consecutive eyes with normal preoperative corneal topography by combined placido and scheimpflug imaging-based topography system (SIRIUS) who underwent LASIK using a microkeratome between 2011 and 2014 at a tertiary level teaching hospital in south India, were retrospectively analyzed. Preoperatively patient''s refraction, flap thickness (FT), ablation depth (AD), residual stromal bed (RSB), and thinnest corneal thickness (TCT) were recorded. The formula used was mPTA = (FT + AD)/TCT. mPTA was grouped into <0.4 (low risk), 0.40 - 0.45 (moderate risk), and >0.45 (high risk). All patients were called for follow-up and underwent a topography to look for ectasia.Results:In total 60.1%, 29.1%, and 10.8% patients had mPTA of <0.4, 0.40 - 0.45 and >0.45, respectively. However, after a minimum follow-up of 2 years, none of the patients had any sign of ectasia.Conclusion:Careful selection of patients is mandatory before proceeding for LASIK. Factors like corneal thickness, RSB, degree of myopia, and AD are more important. The role of mPTA >0.4 as an independent risk factor for post LASIK ectasia is questionable in Indian eyes. Other factors or a modified formula suitable for Indian eyes needs to be investigated. A larger follow-up period is also required as ectasia has been known to develop even after 2 years.     

Long-term course of contrast sensitivity in eyes after laser-assisted in-situ keratomileusis for myopia

Purpose:To evaluate the long-term contrast sensitivity (CS) after laser in-situ keratomileusis (LASIK) for myopia.Methods:This retrospective, single-center, cohort study involved 190 eyes of 95 patients who underwent bilateral LASIK between January 2001 and October 2007. This study includes patients who underwent CS and higher-order aberration (HOA) measurements in a five-year postoperative period. For all enrolled patients, visual acuity, refractive error (RE) in diopters (D), CS at 3-, 6-, 12-, and 18-cycles per degree (cpd), and HOA in a 4 mm area of the dilated pupil were measured before surgery and 6 months, 1 year, and 5 years after it.Results:The mean RE measured before the surgery and after 6 months, 1 year, and 5 years after was - 6.08 ± 2.50D, −0.26 ± 0.65D, −0.28 ± 0.65D, and −0.48 ± 0.80D, respectively. There were no clinically significant changes between preoperative results and the measures taken 6 months, 1 year, and 5 years after surgery. The slight increase in HOA had little effect on CS over the mid to long-term postoperative period.Conclusion:Our findings show that CS does not clinically change post LASIK. Although we were unable to identify the specific mechanism, we theorize that after LASIK there is a possibility for the compensation of HOA.     

高度轴性近视眼白内障手术屈光误差分析

目的:分析高度轴性近视合并老年性白内障患者白内障术后的屈光误差。方法:选择176只高度轴性近视合并老年性白内障眼,眼轴长度≥26mm,行白内障摘除术3个月以上,测量眼轴长度、角膜屈光度、前房深度和眼屈光度数,计算并比较眼轴长度、角膜屈光度测量误差和SRK-公式计算误差。结果:平均眼轴长度测量误差值为0.53mm,平均角膜屈光度测量误差值为0.46D,导致相应的眼屈光度误差值为0.86D和0.45D。SRK-公式计算的平均绝对屈光误差值为1.12D,屈光误差大于2D者占12.5%。结论:公式计算误差和眼轴长度测量误差是导致术后眼屈光度误差的主要原因,且随着眼轴越长,眼轴长度测量误差越大,公式计算的误差也越大。     

高度近视白内障患者小切口非超声乳化术后角膜屈光力的变化

目的：：探讨中老年高度近视白内障患者小切口非超声乳化术后角膜屈光力的变化及手术源性角膜散光( SIA )的特点。方法：回顾性分析我院中老年高度近视白内障行小切口非超声乳化患者103例145眼,角膜曲率计测量术前及术后3d,1wk,1、3mo的角膜水平屈光力值(K1)、垂直屈光力值( K2)及其轴位,采用正弦定律和余弦定律计算法计算SIA值。结果：术后3d,1wk平均角膜散光度与术前相比,差别有统计学意义( P<0.05)。术后1 wk,1、3 mo SIA 值分别为+1.34±0.12,+0.89±0.27和-0.42±0.26,差别有统计学意义(P<0.05)。与术前相比较,术后3d, K1增大1.59D, K2减少1.98D,两者之间有统计学差异( P<0.01);术后3mo内K1和K2与术前的差值均迅速减小,术后3 mo内K1差值比K2差值绝对值小,两者之间各时间点差值的绝对值有统计学差异(P<0.05)。结论：中老年高度近视白内障患者小切口非超声乳化术后短期角膜散光较大,手术方式需进一步改进以减少散光。     

角膜屈光手术患者的白内障摘除联合人工晶体植入手术

目的 研究有角膜屈光手术史患者行白内障摘除植入工晶体度数的确定和术中术后并发症.方法 选取有角膜屈光手术史患者4例4只眼,测量患者的眼轴、角膜曲率和前房深度,分别带入Holladay、Binkhorst及其回归公式计算人工晶体度数,对患者行超声乳化白内障吸除联合人工晶体植入术,术后随访3个月,记录裸眼视力、矫止视力和屈光状态.结果 4例均以选择计算结果中最大的人工晶体度数,结合各自不同的情况有所增减,植入了人工晶体,术后屈光状态与预测值的偏差＜1D;1例在手术中出现了透明角膜隧道切口附近的放射状角膜瘢痕裂开,1例在手术后出现了局限在LASIK角膜瓣区域的角膜水肿.结论 采用多个计算公式同时计算,有可能减小误差,其中,Binkhorst二次回归公式的计算结果预测性比较好.     

Impact of teleconsultation on visual and refractive outcomes in patients undergoing laser refractive surgery during COVID-19

Purpose:To assess the role of remote teleconsultation (TC) follow-up care following a successful and uneventful laser vision correction.Methods:The study is a retrospective, comparative analysis of patients undergoing laser vision correction at tertiary care eye hospital in Southern India. The patients were divided into two groups. The first group included patients operated on before the coronavirus disease (COVID-19) pandemic and were followed up with physical consultations during their follow-up visit (Group 1). The second group comprised patients operated on during the pandemic and had at least one remote TC during their post-operative follow-up (Group 2).Results:A total of 1088 eyes of 564 patients and 717 eyes of 372 patients were included in Group 1 and 2, respectively. The mean number of visits for the patients from Group 2 during the COVID period (2.56 +/- 0.74 days) was significantly lesser (P < 0.0001) than that of Group 1 in the pre-COVID period (3.53 +/- 1.07 days). Close to 90% of the eyes achieved an uncorrected distance visual acuity (UDVA) of 20/20 in both groups (P = 0.925). 96.50% of the eyes in Group 1 and 98.18% of the eyes in Group 2 achieved UCVA 20/25 or better (P = 0.049). Eight eyes (0.73%) in Group 1 and one eye (0.14%) in Group 2 reported a loss of 2 or more lines. However, the results were not statistically significant (P = 0.156). None of the groups had any patients who had a sight-threatening complication.Conclusion:Remote TC following refractive surgery is safe and can be effectively integrated into routine refractive practice to reduce travel to the hospital for a physical consult.     

LASIK术前高度近视眼底病变临床分析及处理

目的探讨准分子激光原位角膜磨镶术（LASIK）术前高度近视眼底病变病情及治疗方法。方法对264例（496只眼）LASIK术前高度近视患者行散瞳眼底检查并作详细眼底检查记录。结果 496只眼中11只眼有干性视网膜裂孔（占2.2%）,9只眼有玻璃体牵引,4只眼伴视网膜脱离,14只眼有严重视网膜变性。11只眼干性视网膜裂孔和2只眼视网膜浅脱离行氩激光光凝治疗,2只眼视网膜脱离行巩膜外硅压术。结论高度近视眼LASIK术前常规散瞳检查眼底对发现病变并及时治疗是非常必要的。     

Comparative study of femtosecond laser‐assisted cataract surgery and conventional phacoemulsification in vitrectomized eyes

Importance

To compare the safety and outcomes of femtosecond laser‐assisted cataract surgery (FLACS) and conventional phacoemulsification in post‐vitrectomy eyes.

Background

To compare visual outcomes and adverse outcomes of FLACS and conventional phacoemulsification in vitrectomized eyes.

Design

Single surgeon, retrospective study set in a private clinic in Auckland, New Zealand. Patients selected in a chronological manner, without masking or randomization.

Participants

Only patients undergoing cataract extraction following vitrectomy were included.

Methods

The last 25 surgeries performed prior to acquisition of the femtosecond laser and the first 25 surgeries performed following acquisition of the femtosecond laser were included. Patient demographic data, preoperative and postoperative visual acuities were collected. Intraoperative and postoperative complications were compared. Follow‐up ranged from 1 to 74 months.

Main Outcome Measures

The main outcome measures are postoperative visual outcomes and intra‐ and postoperative complications for both groups.

Results

Results of FLACS compared to conventional phacoemulsification are as follows: preoperative logMAR best corrected visual acuity (BCVA) (0.63 vs. 0.69), postoperative logMAR BCVA (0.17 vs. 0.19), posterior capsule complications (0% vs. 12%, P = 0.235), cystoid macular oedema (CMO) (12% vs. 20%, P = 0.705) and postoperative neodymium‐doped yttrium aluminium garnet (Nd:YAG) capsulotomy (16% vs. 48%, P = 0.032).

Conclusions and Relevance

FLACS demonstrates comparable visual outcomes to conventional phacoemulsification. Whilst outcomes measured were not statistically significant, except postoperative YAG capsulotomy, FLACS showed a trend towards a better intraoperative and postoperative safety profile. Femtosecond laser offers a theoretical advantage in reducing complication rates in post‐vitrectomy eyes, further larger studies are needed.     

准分子激光角膜屈光手术后丝状角膜炎的临床分析及治疗

目的:观察准分子激光角膜屈光手术后丝状角膜炎的发病情况,总结采用唯地息凝胶治疗的效果,探讨其发病相关因素及防治方法。方法:所有患者2139眼,按术前有无角膜接触镜配戴史分为Ia组493眼(有角膜接触镜配戴史)与Ib组1646眼(无角膜接触镜配戴史),按术式分为IIa组1916眼(LASIK术后)与IIb组223眼(LASEK术后),比较其发病率,观察准分子激光角膜屈光手术后丝状角膜炎的发生情况,发病者迅速、足量使用唯地息凝胶治疗,观察其疗效,分析该病变的临床特征,相关发病因素及防治措施。结果:Ia组与Ib组术后丝状角膜炎发病率分别为3.45%和1.76%,两者有显著差异(P<0.05);IIa组与IIb组术后丝状角膜炎发病率分别为1.93%和4.04%,两者有显著差异(P<0.05)。唯地息凝胶治疗准分子激光角膜屈光手术后丝状角膜炎的平均疗程1.22±0.63d,随访6mo未见复发。结论:与准分子激光角膜屈光手术后丝状角膜炎发生的相关因素包括:术前配戴角膜接触镜继发干眼及眼表炎症、术中角膜损伤、术后角膜上皮愈合及术后用药等。唯地息凝胶治疗准分子激光角膜屈光手术后丝状角膜炎,疗程短、效果显著。     

Clinical outcomes with distance‐dominant multifocal and monofocal intraocular lenses in post‐LASIK cataract surgery planned using an intraoperative aberrometer

Importance

Studies evaluating the clinical benefits of intraoperative aberrometry (IA) in cataract surgery are limited.

Background

The study was designed to determine whether IA improved clinical outcomes of post‐laser in situ keratomileusis (LASIK) cataract surgery with different intraocular lenses (IOLs) implanted.

Design

A retrospective chart review of clinical outcomes from one surgeon at one surgical centre was conducted. It included post‐LASIK cataract surgeries where IA was used for the confirmation of IOL power, with either a distant‐dominant multifocal IOL or a monofocal IOL implanted.

Participants

Records for 44 eyes of 31 patients were analysed.

Methods

Differences in visual acuity (VA) and refractions by lens type were compared, and the effects of IA were evaluated.

Main Outcome Measures

Uncorrected distance VA and the percentage of eyes with a spherical equivalent refraction within 0.5D of the intended correction were the primary outcome measures.

Results

There was no statistically significant difference in the percentage of eyes with uncorrected distance VA of 20/25 or better between IOL groups (P = 0.41). More eyes in the multifocal group had a refraction within 0.50D of intended (P = 0.03). In 39% of cases, the preoperative and IA power calculations suggested the same IOL power. When not equal, the IA results were not significantly more likely to be ‘best’ (P = 0.08).

Conclusions and Relevance

Results suggest that a history of previous LASIK is not a contraindication to use of distant‐dominant multifocal IOLs. IA did not appear to improve clinical outcomes in post‐LASIK eyes, although a positive trend was evident.     

负球差人工晶状体在屈光手术后白内障患者手术中的应用

高度近视眼患者行角膜屈光矫正术后其角膜形态改变,曲率和像差均较正常角膜发生了变化.该类患者按照传统方法计算人工晶状体(intraocular lens,IOL)度数易产生屈光预测误差.屈光术后角膜正球差增加,亦明显影响患者的视觉质量.针对上述问题,目前已有一系列以降低预测偏差为目的的IOL度数计算方法,以期获得更为准确的IOL度数预测值.此外,白内障术前根据角膜球差选择个体化的负球差IOL,能够降低全眼球差,减少患者夜间视力下降、眩光等视觉不适症状,进一步提高患者的视觉和生活质量.     

Barriers for Poor Cataract Surgery Uptake among Patients with Operable Cataract in a Program of Outreach Screening and Low-cost Surgery in Rural China

Aims: To identify the reasons for poor uptake of cataract surgery in a program of outreach screening and low-cost surgery in Pucheng County, a rural area in northwestern China.

Methods: Detailed interviews with a semi-structured questionnaire were conducted by telephone or face-to-face for participants who had been advised to attend a low-cost cataract surgery program but did not schedule the surgery within 3 months after the initial screening.

Results: Among 432 eligible subjects, 355 (82.2%) were interviewed (mean age 70.6?±?6.6 years, 73.8% female). A total of 138 subjects (38.9%) were interviewed by phone and 217 (61.1%) were interviewed face-to-face. Lack of family support (n?=?106, 29.9%) and failure to understand the need for surgery (n?=?96, 27.0%) were the two main reasons for not undergoing cataract surgery. Other factors included fear of surgery (n?=?62, 17.5%), lack of faith in doctors (n?=?36, 10.1%), financial constraints (n?=?25, 7.0%) and lack of transportation (n?=?4, 1.1%).

Conclusion: The principal barriers to low-cost cataract surgery uptake in rural China included lack of family support and failure to understand the need for surgery. Education targeting entire families to eliminate these barriers and development of community support systems at the family level are required to achieve greater uptake of low-cost cataract surgery programs in rural China.     

正常角膜伴近视散光眼角膜各形态参数分布特征及与全眼屈光参数的关系

目的 探讨正常角膜伴近视散光眼角膜各形态参数分布特征及与全眼屈光参数的关系.方法 收集102例(204眼)近视患者,分别应用非接触眼压计、检影仪、A超、角膜超声测厚仪、Pentacam三维眼前节分析仪进行眼压、屈光度、眼轴长度、角膜厚度、角膜前后表面形态参数等测量,应用SPSS 13.0统计学软件进行数据分析.结果 正常角膜伴近视散光眼角膜中央厚度(537.06±25.45)μm,角膜中央前表面高度(2.35±1.39)μm,中央后表面高度(3.60±2.73) μm,角膜Q值(8 mm范围)-0.30±0.10,角膜最薄点距角膜顶点距离(0.59±0.19)mm,角膜最薄点位置多位于角膜顶点颞下方,占91.67％.角膜最薄点至周边厚度增长变化指数为1.04±0.13.角膜中央前后表面高度、角膜Q值、角膜最薄点至周边厚度增长变化指数与等效球镜、眼压、眼轴长度无明显相关性(均为P＞0.05).结论 正常角膜伴近视散光眼角膜形态各项参数分布值各有特点,与全眼屈光参数无明显相关性.     

Citation analysis of the most influential authors and ophthalmology journals in the field of cataract and corneal refractive surgery 2000-2004

Purpose: To identify the most published authors on the topics of ‘cataract’ and ‘LASIK’, the journals in which they publish, and the citation patterns of the most‐cited articles by these authors over a 5‐year publication period. Methods: Science Citation Index Expanded (SCI) was used to identify the 30 most‐published authors in ‘cataract’ and ‘laser in situ keratomileusis’ (LASIK) (2000–2004 inclusive). SCI was subsequently used to analyse the recorded articles for each author in terms of source journal, the most commonly cited articles and citation source. Results: Of the 30 most‐published authors in the fields of cataract and LASIK, the USA was the most well‐represented source country, accounting for 33%; 20% were from Australia, and 17% from Austria. Germany and Japan each contributed 7%. Eighty per cent of the publications produced by these 30 authors (2000–2004) were in 10 journals, of which the Journal of Cataract and Refractive Surgery (JCRS) published more than one‐third. Of the three most‐cited articles for each author, the greatest number were published in JCRS (35.6%). The citation count of the articles had a weak correlation to the journal impact factor of the source journal; however, the self‐citation rate of these articles did not. Conclusions: The USA and Australia together were the source of more than half of the most‐published authors on cataract and LASIK and the majority of articles published by the 30 most prolific authors were published in only 10 journals. The impact factors of the publication journals preferred by these authors are influenced by the article citation counts, not vice versa.     

Refractive surgery with simultaneous collagen cross-linking for borderline corneas - A review of different techniques,their protocols and clinical outcomes

Simultaneous corneal cross-linking (CXL) has been proposed as an adjunct therapy to corneal refractive procedures to prevent future ectasia, especially when performed in borderline corneas. This review analyses the currently available literature (minimum follow-up 6 months) on corneal refractive surgery and simultaneous CXL (PRK Xtra, LASIK Xtra, and SMILE Xtra) to evaluate the overall results including the safety, efficacy, and potential complications associated with these procedures. A comprehensive literature search of various electronic databases (PubMed, PubMed Central, Cochrane database, and MEDLINE) was performed up to 20^th May 2020. Four relevant studies were found for PRK Xtra, 12 for LASIK Xtra, and 3 for SMILE Xtra. The total number of eyes included in this review was 1,512: 294 for PRK Xtra, 221 for PRK-only, 446 eyes for LASIK Xtra, 398 eyes for LASIK-only, 91 for SMILE Xtra and 62 for SMILE-only. Current literature suggests that refractive surgery and simultaneous CXL is generally safe and delivers comparable results in terms of visual and refractive outcomes than refractive surgery alone. However, there is no consensus on a standard cross-linking protocol, and complications such as diffuse lamellar keratitis, central toxic keratopathy, and corneal ectasia following Xtra procedures have been reported. It is therefore suggested that surgeons exercise caution in case-selection and counsel their patients regarding the potential risks and benefits with Xtra procedures. Also, further studies are required to standardize the UV-A irradiation protocols and to evaluate the long-term effect on safety, refractive predictability, and stability of these procedures.     

Comparative clinical outcomes of Tecnis toric IOL implantation in femtosecond laser-assisted cataract surgery and conventional phacoemulsification surgery

AIM: To compare the short-term visual outcomes, residual refractive cylinder, and rotation stability after Tecnis toric intraocular lens (IOL) implantation during femtosecond laser-assisted cataract surgery (Femto phaco) and conventional phacoemulsification surgery (Conventional phaco). METHODS: In a prospective cohort study, Conventional phaco and Femto phaco (anterior capsulotomy and lens fragmentation by a femtosecond laser) with Tecnis toric IOL implantation were performed in 40 eyes from 36 patients and 37 eyes from 33 patients, respectively. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were assessed during 1d, 1wk, and 1mo follow-ups. The orientation of the Tecnis Toric IOL was evaluated during 1wk and 1mo follow-ups. RESULTS: There were no significant differences in UDCA or CDVA between two groups at 1mo postoperatively, though relatively more subjects had UDVA values of 20/25 or better in Femto phaco group than in the Conventional group (P>0.05). A lower but not significantly lower rate of having more than 5° of IOL rotation was observed in Femto phaco group at the 1-month follow-up, while a significant lower rate of residual astigmatism of ≤1 D was observed in Femto phaco group. CONCLUSION: The Femto phaco group has significantly more subjects with the residual astigmatism of ≤1 D, but there are no significant differences in rotation stability and visual outcomes as compared with the Conventional phaco group after the application of the Tecnis toric IOL in this cohort.     

Value of dual biometry in the detection and investigation of error in the preoperative prediction of refractive status following cataract surgery

Purpose: To report the value of dual biometry in the detection of biometry errors. Methods: Study 1: retrospective study of 224 consecutive cataract operations. The intraocular lens power calculation was based on immersion biometry. Study 2: immersion biometry was compared with optical coherence biometry (OCB) in terms of axial length, anterior chamber depth, keratometry readings and the recommended lens power to achieve emmetropia. Study 3: prospective study of 61 consecutive cataract operations. Both immersion and OCB were performed, but lens power calculation was based on the latter. Results: Study 1: 115 (86%), 101 (75.4%), 90 (67.2%) and 50 (37.3%) of postoperative spherical equivalents were within ±1.5 dioptres (D), ±1.25 D, ±1 D and ±0.5 D of the target, respectively. Study 2: excellent agreement between axial length readings, anterior chamber depth readings and keratometry readings by immersion biometry and OCB was observed (reflected in a mean bias of ?0.065 mm, ?0.048 mm and +0.1803 D, respectively, in association with OCB). Agreement between the lens power recommended by each technique to achieve emmetropia was poor (mean bias of +1.16 D in association with OCB), but improved following appropriate modification of lens constants in the Accutome A‐scan software (mean bias with OCB = ?0.4 D). Study 3: 37 (92.5%) and 23 (57.5%) of operated eyes achieved a postoperative refraction within ±1 D and ±0.5 D of target, respectively. Conclusion: Systematic errors in biometry can exist, in the presence of acceptable postoperative refractive results. Dual biometry allows each biometric parameter to be scrutinized in isolation, and identify sources of error that may otherwise go undetected.     

Comparative analysis of the clinical outcomes between wavefront-guided and conventional femtosecond LASIK in myopia and myopia astigmatism

AIM: To compare the clinical outcomes of wavefront guided femtosecond LASIK (WFG LASIK) and conventional femtosecond LASIK (NWFG LASIK) in eyes with myopia and myopia astigmatism. METHODS: This was a retrospective, nonrandomized, comparative investigation enrolling 236 eyes of 122 patients (18-50y) with low & moderate and high myopia. The WFG group including 97 eyes (50 patients) undergone WFG LASIK and the NWFG group including 139 eyes (72 patients) undergone conventional LASIK. Mean efficacy index, high order aberrations (HOAs), pupil size and the quality of visual questionnaire were evaluated 6mo postoperatively. RESULTS: There is no difference between WFG group (-0.054±0.049 in logMAR) and NWFG group (-0.040±0.056) in uncorrected distance visual acuity (UDVA) postoperatively. The myopia astigmatism is higher in WFG group than that in NWFG group (P<0.05). However, the mean efficacy index (MEI) in the WFG group (1.09±0.106) is better than that in the NWFG group (1.036±0.124; P<0.001). Increased HOAs were observed in NWFG group (0.30±0.196) than that in WFG group (0.146±0.188; P<0.001). The pupil size is larger in WFG group (5.15±0.76 mm) than that in NWFG group (4.32±0.52 mm). The patients are satisfied with the clinical surgery, yet WFG group showed better visual quality using the questionnaire survey. Meanwhile, high myopia would result in worse MEI, HOAs and visual quality than low & moderate myopia. CONCLUSION: WFG and NWFG FS-LASIK are both effective and safe procedures to correct low & moderate and high myopia, but WFG FS-LASIK gives a better postoperative MEI, aberrometric control and predictable outcome. Meanwhile, WFG FS-LASIK is better than NWFG FS-LASIK in correction of myopia astigmatism. Low & moderate myopia allow better clinical outcomes than high myopia using any surgical method.