接触镜导致角膜病变的临床分析与防治

通过３ａ的大学生体检结果看出,视力下降逐年增多,屈光不正占总调查人数的６０％．调查中,大部分患者配戴一般眼镜,少数患者因种种原因不能接受镜片的矫正。如：屈光参差、高度近视（＞－６．００Ｄ）因镜片过厚不方便等因素选戴接触镜。但对角膜的影响随即而出,现将...     

软性角膜接触镜的不良反应及并发症

随着软性角膜接触镜（ＳＣＬ）广泛应用，所引起的眼部不良反应及并发症日益增多，引起眼科界及眼镜行业的高度重视。近年来的研究结果表明：①ＳＣＬ导致角膜微环境改变，包括低氧状态，二氧化碳潴留，ｐＨ值上降，渗透压及温度变化。②ＳＣＬ引起角膜功能及结构异常，包括上皮微囊形成，角膜敏感度下降及上皮变薄，基质水肿、变薄及新生血管形成，内皮细胞多相性改变及细胞数目减少。③ＳＣＬ并发眼部炎症及感染，包括滤泡性结膜炎     

与接触镜相关的角膜疾病及其防治

角膜接触镜的增视，美容和方便的特点使其在世界各地被广泛使用。但在其配戴过程中，可引起一系列的眼部生理变化，如：角膜厚度增加，角膜电位改变，葡萄糖代谢改变，角膜缺氧，二氧化碳分压增加，ＰＨ值下降，角膜表面温度下降等，对某些长期配戴，还可能发生各种较严重的并发症，如：微生物性角膜炎，代谢性，毒性和变应性角膜病变。本就此及其防治作简要综述。     

角膜散光与软性角膜接触镜配适评估的相关性分析

目的探讨角膜散光的大小、轴向与球性、散光软性角膜接触镜的配适状态、舒适度之间的关系。设计前瞻性随机区组对照临床研究。研究对象284例自愿受试者,现在或曾经配戴软性角膜接触镜。方法受试者的平均近视屈光度为(-5.18±2.53)D,平均散光度为(0.81±0.50)D。每位受试者在接受眼部检查、验光、角膜地形图检查后,于其左眼间隔一定的时间先后配戴球性和散光软性接触镜。根据受试者左眼角膜散光的轴向将人群分为三组:第一组,顺规散光组(132眼);第二组,逆规散光组(76眼);第三组,斜轴散光组(76眼)。同时,根据受试者角膜散光度数的不同分为以下三组:第四组,<0.75D共153眼;第五组,≥0.75D、<1.50D,共106眼;第六组,≥1.50D共25眼。主要指标镜片中央定位、覆盖度、活动度、散光镜片的旋转性和稳定性以及舒适度。结果在前三组和后三组对比中,镜片覆盖度、活动度、旋转性及稳定性指标组间均无显著性差异。散光镜片的稳定性在3分钟、15分钟明显优于第1分钟。散光镜片的中央定位优于球性软镜(P=0.00),最佳中央定位的比例分别为54%与48%;散光镜片活动度大于球镜(P=0.02),两者活动度不良所占的比例分别为18%与19%;散光镜片舒适度差于球镜(P=0.00),不可接受的比例散光片为14%,球镜片为5%。结论软性角膜接触镜的配适与舒适度较少地受到角膜散光的影响。球性软镜可在一定程度上作为首选配戴。     

软性角膜接触镜治疗大泡性角膜病变

目的：评价软性角膜接触镜（soft contact lens,SCL)在大泡性角膜病变治疗中的作用。方法：17例大泡性角膜病变患者配戴SCI,每月更换1次,随访观察患者临床症状是否改善及有无并发症出现。结果：17例患者随访2－22mo,临床症状都得到一定改善,无明显并发症出现。结论SCL能明显改善大泡性角膜病变患者的临床症状,提高患者的生活质量。     

接触镜相关性角膜新生血管形成临床分析

目的 探讨软性接触镜（ＳＣＬ）相关笥角膜新生血管形成（ＣＮＶ）的流行这、临床表现、危险因素与预防措施。方法 对１９９５年７月～１９９７年６月验配ＳＣＬ的屈光不正患者ＣＮＶ发生情况进行回顾性分析。结果 配前检查时,重配者中,ＣＮＶ阳性者（〉０．６ｍｍ）占７．４％,多位于角膜上下部的浅基质层,症状轻微,其中５１．９％有长戴史,４８．２％有配适问题,７４．１％护理不当,无定期复查者,初配者中,０．４％有     

长期戴用软性接触镜后角膜内皮细胞的改变

目的：观察软性接触镜长期戴用后对角膜内皮细胞的影响,探讨如何提高ＳＣＬ使用的安全度。方法;利用非接触式角膜内皮显微镜（ＳＰ－５００,ＳＥＥＤ Ｃｏ．Ｌｔｄ）,观察长期戴用ＳＣＬ的４８只眼角与角膜内皮细胞的改变。分为日间戴镜组和连续过夜戴镜组,并分别探讨戴镜期间的长短与角膜内皮变化的关系。同年龄组正常非戴镜眼的角膜内皮细胞参数作为对照观察。     

短期配戴角膜接触镜对角膜形态和厚度的影响

目的探讨短期配戴软性角膜接触镜对角膜形态和厚度的影响。方法对25名青壮年近视志愿者(50眼)(等值球镜:-0.50~-7.25 D)统一配戴软性角膜接触镜1个月,测定摘镜后1个月内不同时间的角膜形态和厚度变化,并与戴镜前比较。结果戴镜前和摘镜后不同时间,角膜地形图形态构成、角膜地形图散光轴向的变化构成及一些角膜前表面形态相关指数无显著性差异(P>0.05)。戴镜前与摘镜后角膜地形图形态完全一致者占62.5%,且均以不对称领结形为著;在摘镜后1 d、1周、2周,角膜地形图散光轴向变化在16°以上及31°以上均超过30%和20%,直到1个月后仍有24%的眼角膜地形图散光轴向的变化在16°以上;角膜厚度在摘镜后1 d、2周均明显高于戴镜前(P<0.05),直到1个月后才与戴镜前接近,且受日均戴镜时间的影响。结论短期配戴软性角膜接触镜对角膜形态和厚度的影响虽轻微但复杂,摘镜后1 d变化最显著,随着时间的延长逐渐恢复,直到1个月后才与戴镜前基本一致。日均戴镜时间对摘镜后角膜厚度变化有影响。     

Relationship between corneal tissue and shape in short-term soft contact lens wear

Purpose

To investigate which morphometric and ocular surface tissue parameters are affected by short-term soft contact lens (CL) wear and to assess whether they carry related or independent information.

Methods

Twenty-two healthy participants wore silicone hydrogel (SiHy; MyDay, CooperVision) soft CLs for 8 h in their left eye. Corneal tomography and corneoscleral topography were captured before and immediately after CL wear. Central corneal thickness (CCT), corneoscleral parameters (limbus position and corneoscleral junction [CSJ] angle) and corneal tissue parameters (corneal transparency and homogeneity) were evaluated.

Results

Corneoscleral parameters (limbus position and CSJ angle) were independent of corneal tissue parameters (transparency and homogeneity) at baseline and after CL wear. CCT was independent of all the other parameters examined at baseline, but baseline values of corneal tissue parameters were moderately correlated with CCT change (transparency: r = −0.51; p = 0.007), homogeneity: r = −0.46; p = 0.02).

Conclusions

A complete characterisation of ocular surface changes following CL wear should consider corneoscleral topography and corneal densitometry simultaneously, since they carry complementary information.     

The physiologic effects of extended wear soft contact lenses

The major physiologic effect to the eyes of soft contact lenses in general and continuously worn hydrogel lenses in particular is a decrease in the amount of oxygen normally available to the cornea. This reduction in oxygen supply produces changes as minimal as clinically undetectable epithelial edema and as severe as the anoxic overwear syndrome that produces pain and decreased vision. Induced corneal edema can produce refractive error changes and endothelial cell changes. On a long-term basis the lenses produce physical trauma to the anterior surface of the cornea as well as certain metabolic changes and have been associated with a significant degree of corneal neovascularization. Because hydrogel lenses require a different type of care than standard, hard PMMA lenses, new complications are being described, such as giant papillary conjunctivitis, lens deposits, and acute red eye syndromes that may be associated with allergic or toxic reactions to preservatives used in the cleaning processes. Research is underway to develop hydrogel materials that will allow more oxygen to reach the corneal surface and prevent surface deposits from forming.     

Contact lens associated keratopathy

A case of bilateral subepithelial corneal deposits is reported in a 29-year-old disposable contact lens wearer. The deposits disappeared within 13 months of changing the disinfection system. A drug-related mechanism is possible. (Clin Exp Optom 1993; 76: 5: 172–173)     

Acanthamoeba keratitis and contact lens wear

Acanthamoeba keratitis is a rare but serious complication of contact lens wear that may cause severe visual loss. The clinical picture is usually characterised by severe pain, sometimes disproportionate to the signs, with an early superficial keratitis that is often misdiagnosed as herpes simplex virus (HSV) keratitis. Advanced stages of the infection are usually characterised by central corneal epithelial loss and marked stromal opacification with subsequent loss of vision. In this paper, six cases of contact lens‐related Acanthamoeba keratitis that occurred in Australia and New Zealand over a three‐year period are described. Three of the patients were disposable soft lens wearers, two were hybrid lens wearers and one was a rigid gas permeable lens wearer. For all six cases, the risk factors for Acanthamoeba keratitis were contact lens wear with inappropriate or ineffective lens maintenance and exposure of the contact lenses to tap or other sources of water. All six patients responded well to medical therapy that involved topical use of appropriate therapeutic agents, most commonly polyhexamethylene biguanide and propamidine isethionate, although two of the patients also subsequently underwent deep lamellar keratoplasty due to residual corneal surface irregularity and stromal scarring. Despite the significant advances that have been made in the medical therapy of Acanthamoeba keratitis over the past 10 years, prevention remains the best treatment and patients who wear contact lenses must be thoroughly educated about the proper use and care of the lenses. In particular, exposure of the contact lenses to tap water or other sources of water should be avoided.     

Solving soft contact lens problems

Soft contact lens wearers encounter a variety of problems affecting their vision and comfort. Six patients with soft lens-related problems are discussed, illustrating the various sources of problems and approaches to their solution.     

Corneal oedema during reverse piggyback scleral lens wear

Purpose

One clinical approach to address poor front surface wettability during scleral lens wear is the use of a “reverse piggyback” system (a soft contact lens applied to the anterior surface of a scleral lens). The aim of this study was to compare the magnitude of corneal oedema induced following short-term reverse piggyback scleral lens wear and standard scleral lens wear.

Methods

Ten young (mean age 22 ± 6 years) healthy participants with normal corneas were recruited. On separate days, central corneal thickness and fluid reservoir thickness were measured using optical coherence tomography before and after 90 min of standard scleral lens wear (Kerectasia Alignment Tangent Torus diagnostic lenses, hexafocon A, Dk 100 × 10⁻¹¹ (cm²/s)(ml O₂/ml × mmHg), Capricornia Contact Lenses, capcl.com.au ) and reverse piggyback scleral lens wear (the same scleral lens with a Dailies Total 1®, delefilcon A, Dk 140 × 10⁻¹¹ (cm²/s)(ml O₂/ml × mmHg), Alcon, alcon.com , applied to the anterior scleral lens surface).

Results

After correcting for small variations in the initial central fluid reservoir thickness, central corneal oedema was similar between the reverse piggyback (2.32 ± 1.15%) and standard scleral lens conditions (2.02 ± 0.76%; p = 0.45).

Conclusions

Following 90 min of lens wear, the highly oxygen-permeable reverse piggyback system did not induce a clinically or statistically greater magnitude of central corneal oedema compared with standard scleral lens wear in young adults with healthy corneas. This approach may be suitable to address poor front surface scleral lens wettability or to correct residual refractive error during diagnostic scleral lens fitting.