Specular microscopy of hard contact lens wearers II

Specular microscopy was done on 65 long-term hard contact lens (CL) wearers and controls matched for age, sex, race, and refractive error. There was no difference in mean endothelial cell size between the two groups, although median cell area was slightly smaller in the CL group. Standard deviation and coefficient of variation increased as the duration of total wearing time increased and were greater in the CL group, as was skewness. In 15 long-term hard CL wearers who had discontinued their CL wear, there was a trend towards persistence of pleomorphism and polymegathism of cells compared with non-contact lens (NCL) wearers, but there was a suggestion of recovery compared with those continuing to wear CLs matched for duration of wear.     

Specular microscopy of unilateral hard contact lens wearers

The effects of long term wear of PMMA contact lenses on the corneal endothelium used on a daily wear basis were determined by examining 8 patients who had been prescribed lenses in one eye only. The patients excluded unilateral aphakes. It was found that a significant reduction in the cell density and a change in the cell size and shape was induced by PMMA lenses. These changes reflect an endothelial metabolic stress and emphasize the need to find newer lens materials that are more oxygen permeable and produce little interference with the corneal metabolism.     

佩戴角膜接触镜后角膜变化的激光共焦显微镜观察

目的 应用激光共焦显微镜对长期佩戴角膜软性接触镜的患者活体角膜的组织结构变化进行观察.方法 用激光共焦显微镜对长期佩戴角膜软性接触镜的15例患者进行检查,并选择未戴角膜接触镜者11例进行对照,对两组结果进行比较.结果 1.佩戴角膜软性接触镜组与对照组相比,基底上皮细胞密度减少,为3705.00±447.62个/mm2(P＜0.05),角膜上皮层厚度变薄,为54.3±8.44μm(P＜0.05),并有部分剥脱.2.佩戴角膜软性接触镜组角膜内出现白色点状物,朗汉氏细胞数目多,成树枝状改变.3.角膜软性接触镜组与对照组相比神经纤维数量及密度无明显变化(P＞0.05),但曲折度增加,有分支出现(P＜0.05).结论 佩戴角膜软性接触镜,角膜组织可发生一系列改变,激光共焦显微镜与传统光学共焦显微镜相比,图象清晰,深度定位准确,在疾病的早期诊断、治疗和研究中将起重要作用.     

长期配戴软性接触镜后角膜组织的病理改变

目的：探讨配戴不同时间软性接触镜( SCL)后对患者角膜组织的病理变化。
　　方法：应用共焦显微镜分别检查中低度近视SCL组(150例)和对照组(150例)戴镜1,3,5,8,10a以上的中央角膜和周边角膜的变化。
　　结果：戴镜5 a后SCL组中央角膜基底细胞密度低于对照组(P<0.05),上皮层可见微小囊泡及类似角膜营养不良的角膜小滴,上皮下Langerhans细胞密度及神经纤维曲折度大于对照组( P<0.05)。 SCL组中央角膜浅基质层细胞密度低于对照组(P<0.05),各组基质层中白色点状物密度均高于对照组( P<0.05)。 SCL组内皮细胞形态变化明显,但两组内皮细胞密度无差异( P>0.05)。 SCL组中央角膜上皮层厚度小于对照组(P<0.05)。
　　结论：SCL引起角膜组织的改变随戴镜时间的延长逐渐明显,且这种改变不容忽视。     

Tear ferning in contact lens wearers

Tear ferning (TF) has shown good sensitivity and specificity in the diagnosis of dry eye, but is a relatively uncommon test, especially in contact lens wearers. The aim of this study was to investigate the relationship between TF, ocular comfort and tear film stability amongst contact lens (CL) wearers and non-contact lens (NCL) wearers. Subjects (36 NCL, 24 CL; mean age 23.2 ± 4.8 years) underwent assessment of non-invasive tear break up time (NIBUT), fluorescein tear break up time (FBUT) and completed the Ocular Comfort Index (OCI) questionnaire. Non-stimulated tears were collected from the inferior tear meniscus with a glass capillary. Samples of 1.5 μL were air dried, observed by light microscopy and the TF pattern quantified according to Rolando's grading scale. Significantly higher grades of TF pattern and discomfort (higher OCI scores) were observed in CL wearers compared to NCL wearers (Mann–Whitney U -test; p  < 0.005 and p  < 0.05 respectively). Differences in tear film stability were not significant between groups. Even when asymptomatic (low OCI scores) CL and NCL subjects were compared, TF remained significantly different ( p  < 0.005). In both CL and NCL subjects, TF displayed poor correlation with tear film stability tests and OCI scores. Higher TF grades in CL wearers, even if asymptomatic, indicate an unfavourable ratio of salt to macromolecule concentration within the tear film of such subjects. The lack of significant difference in TF between symptomatic CL and NCL wearers could suggest similar aetiology (tear film hyperosmolarity) in each cohort. The TF technique demonstrates limited sensitivity and specificity for the prediction of ocular surface comfort in both CL and NCL wearers.     

Presence of inflammatory mediators in the tears of contact lens wearers and non-contact lens wearers

The present studies have demonstrated the levels of N-methyl histamine in tears from normal physiological states, pathological states and contact lens wear Histamine was significantly increased in closed eye tears compared with both open and reflex tears. Tears from other ocular conditions had low levels of histamine except for environmental hypersensitivity, which contained significantly elevated levels compared to normal tear types. Interestingly tears from asymptomatic contact lens wearers had significant levels of histamine whereas tears from contact lens adverse events had lower levels, possibly reflecting a change in histamine metabolism.     

Non-compliance with lens care and maintenance in diabetic contact lens wearers

We hypothesize that diabetic contact lens wearers may represent a special group displaying higher levels of compliance with their lens care regimens as a result of learned behaviour relating to maintenance of their diabetic condition. To test this hypothesis, a prospective, single centre, controlled, masked study was performed whereby 29 diabetic contact lens patients and 29 non-diabetic control subjects were issued with disposable hydrogel contact lenses and a multipurpose lens care regimen. All participants were given identical instruction on lens care and maintenance. Compliance levels were assessed at a 12-month aftercare appointment by demonstration and questionnaire. Twenty-four different aspects of compliance were scored, 12 by observation and 12 by questionnaire report, of which only two showed a significant difference between the diabetic and control groups. Although the combined population of contact lens wearers was generally compliant, there were examples of non-compliance in both groups. Neither the duration of diabetes nor the degree of metabolic control appeared to have a significant effect on compliance. The results suggest that eye care practitioners cannot assume that diabetic patients will be more compliant with contact lens care and maintenance than non-diabetic patients.     

Blepharoptosis in RGP and PMMA hard contact lens wearers

Background: Contact lens wear has been documented to cause an acquired non‐senile blepharoptosis. This is generally associated with prolonged wearing of hard contact lenses. The aim of this study was to determine the clinical features of blepharoptosis associated with contact lens wear including the type of contact lens and the duration of wear. Methods: This is a retrospective study of consecutive patients seen over four years (1997 to 2001) in the private practice of an oculoplastic surgeon. Results: A total of 15 consecutive patients presented over the four‐year period with blepharoptosis in the context of prolonged contact lens use. Four of the 15 patients (27 per cent) were wearing rigid gas permeable (RGP) lenses. The rest had been wearing PMMA hard lenses. Thirteen patients (87 per cent) had been wearing their contact lenses for more than 17 years. The patients' ages ranged between 15 and 71 years with a mean age of 46 years. All 15 patients had normal levator palpebrae superioris function. Four patients (27 per cent) had bilateral involvement. Eleven patients (73 per cent) underwent ptosis repair where aponeurosis thinning/dehiscence was noted. When compared with patients who presented over the same period with other causes of blepharoptosis (traumatic, myopathic, anophthalmic and involutional), contact lens wear was found to be an uncommon cause of ptosis across all age groups. Conclusion: The majority of contact lens wearers presenting with blepharoptosis gave a history of prolonged use of hard contact lenses. One explanation for this would be the mechanisms of removal of hard contact lenses. This involves pulling the lids laterally at the lateral canthus followed by a harsh blink, which over years can lead to levator aponeurosis dehiscence. Contact lens associated ptosis is an uncommon cause of acquired ptosis across all age groups.     

Serotype and adhesion of Pseudomonas aeruginosa isolated from contact lens wearers

The purpose of the present study was to correlate the serotypes of Pseudomonas aeruginosa to the bacterial adhesion to contact lenses and human corneal epithelial cells. Twenty‐three strains isolated from contact lens wearers were used for the study. The bacterial serotypes were examined with a P. aeruginosa antisera kit. The attachment of bacteria on contact lenses or human corneal epithelial cells was determined by counting the number of adhered bacteria after incubation of the bacteria with contact lenses or corneal epithelial cells. The 23 ocular isolates belonged to seven serotypes. Strains of serotypes I, G and E were the three dominant serogroups and were more adhesive to contact lenses compared with other groups of the bacteria. The bacterial serotypes and the clinical sequelae were not strongly related. These results indicate that the surface characteristics of bacterial serotypes are related to the bacterial adhesion to the surface, but the pathogenesis of the bacteria may result from multiple factors.     

配戴RGPCL和SCL后角膜组织病理学变化的比较

目的 探讨配戴硬性透气性角膜接触镜（RGPCL）和软性角膜接触镜（SCL）对角膜组织的影响.方法 病例对照研究.高度近视患者60例,30例配戴RGPCL,30例配戴SCL.在配戴3、6、12个月后,应用激光共焦显微镜检查两组患者的中央角膜和周边角膜上皮层、上皮下Langerhans细胞、神经纤维、角膜基质层、角膜内皮细胞及角膜厚度的变化.采用两因素方差分析对数据进行分析.结果 戴镜1年后,SCL组中央角膜表层细胞密度低于RGPCL组（F=4.262,P＜0.05）,上皮层可见微小囊泡及类似角膜营养不良的角膜小滴,上皮下Langerhans细胞密度及神经纤维曲折度均大于RGPCL组（F=5.362,P＜0.05;F=-14.910,P＜0.05）.SCL组中央角膜浅基质层细胞密度低于RGPCL组（P＜0.05）,基质层中各层白色点状物密度均高于RGPCL组（P＜0.05）.SCL组内皮细胞形态变化较RGPCL组明显,但两组内皮细胞密度差异无统计学意义.SCL组中央角膜上皮层厚度小于RGPCL组（F=-2.061,P＜0.05）.同一戴镜组内各个观察指标在3个月、6个月、12个月间的差异均无统计学意义.结论 RGPCL配戴者角膜上皮细胞、前基质细胞、内皮细胞、Langerhans细胞及神经纤维的变化均轻于SCL配戴者,提示RGPCL的安全性更高.     

Effects of contact lens wearing on keratoconus: a confocal microscopy observation

AIM: To evaluate the corneal cell morphology of new keratoconus patients wearing two different types of rigid gas-permeable (RGP) contact lenses for 1y. METHODS: Thirty nine eyes of 39 new keratoconus patients were selected and randomly fitted with two types of RGP contact lenses. Group 1 had 21 eyes with regular rigid gas-permeable (RRGP) contact lens and rest 18 eyes were in group 2 with specially designed rigid gas-permeable (SRGP) contact lens. Corneal cell morphology was evaluated using a slit scanning confocal microscope at no-lens wear and after 1y of contact lens wearing. RESULTS: After 1y of contact lens wearing in group 1, the mean anterior and posterior stromal keratocyte density were significantly less (P=0.006 and P=0.001, respectively) compared to no-lens wear. The mean cell area of anterior and posterior stromal keratocyte were also significantly different (P=0.005 and P=0.001) from no-lens wear. The anterior and posterior stromal haze increased by 18.74% and 23.81%, respectively after 1y of contact lens wearing. Whereas in group 2, statistically significant changes were observed only in cell density & area of anterior stroma (P=0.001 and P=0.001, respectively) after 1y. While, level of anterior and posterior stromal haze increased by 16.67% and 11.11% after 1y of contact lens wearing. Polymegathism and pleomorphism also increased after 1y of contact lens wearing in both the contact lens groups. CONCLUSION: Confocal microscopy observation shows the significant alterations in corneal cell morphology of keratoconic corneas wearing contact lenses especially in group 1. The type of contact lens must be carefully selected to minimize changes in corneal cell morphology.     

Oxygen permeability of hard gas permeable contact lens materials

Oxygen transmissibility (Dk/L) data of contact lenses enables prediction of the ocular response during wear. However, there has been difficulty in relating the data from highly permeable rigid lens materials to models predicting corneal swelling based upon the Dk/L of soft lenses. We have examined the methodology used to determine the oxygen permeability (Dk) of hard gas permeable (HGP) materials, and have applied a measurement technique that overcomes certain deficiencies of previous methods. A representative range of HGP and hydrophilic lens materials was measured. The Dk values reported here for hydrophilic materials are in close agreement with those published elsewhere. However, the Dk values of HGP materials were found to be substantially less than those reported previously, although the relative ranking appears to be independent of measurement technique. Possible explanations of these findings are presented.     

硬性透气性角膜接触镜与软性角膜接触镜对中低度近视患者角膜形态的影响

目的　探讨屈光不正患者长期配戴软性角膜接触镜（soft contact lens,SCL）和硬性透气性角膜接触镜（rigid gas permeable contact lense,RGPCL）对角膜形态参数的影响。方法　收集视光学中心验配角膜接触镜的屈光不正患者60例(120眼),按照患者配戴SCL或RGPCL分为SCL组和RGPCL组（两组均为30例60眼）,在戴镜前及戴镜后1 a、2 a测量2组患者中央角膜厚度、内皮细胞密度、六角形细胞比例及变异系数,并对2组数据进行对比。结果　SCL组:戴镜后2 a,中央角膜厚度(509±31)μm较戴镜前(549±26)μm明显下降（P<0.05）;角膜内皮细胞密度为(2819.3±169.2）个·mm^-2,较戴镜前密度(3182.6±162.3）个·mm^-2减少;六角形细胞比例（51.52±4.69）%较戴镜前（61.45±4.58）%降低（P<0.05）;内皮细胞变异系数（39.14±3.15）较戴镜前（33.47±2.83）增加（P<0.05）。RGPCL组戴镜前后中央角膜厚度、角膜内皮细胞密度、六角形细胞比例及内皮细胞变异系数比较,差异均无统计学意义（均为P>0.05）。结论　与配戴SCL相比,配戴RGPCL对屈光不正患者的角膜形态和功能影响不明显,更适合长期配戴。     

Preliminary tear film measurements of tolerant and non-tolerant contact lens wearers

Background : The relationship between contact lens intolerance and tear stability, tear quantity, distribution and consistency has yet to be clearly established. In this study, we have examined the tear film of several tolerant and non-tolerant soft contact lens wearers. We aimed to develop a number of clinical and biochemical techniques to establish a correlation between one or more factors leading to contact lens intolerance. Methods : Subjects were separated by their self-described tolerance to contact lens wear. Five tolerant and five non-tolerant subjects were chosen. A McMonnies symptomatology questionnaire was used to ascertain subject history, while non-invasive tear break-up time (TBUT) examined tear stability. Basal tear collection was performed using glass capillary tubes, the tear flow rate was measured and one dimensional gel electrophoresis used to analyse protein differences. Results : Non-tolerant subjects experienced primary symptoms, such as dryness and grittiness, more often than tolerant subjects (p = 0.007). The TBUT of non-tolerant lens wearers was also reduced (average of seven seconds) compared to tolerant lens wearers (p < 0.002). Tolerant lens wearers had a longer more stable tear film with an average TBUT of 20 seconds and this correlated with a fast tear flow rate (p < 0.04). Protein gel electrophoresis showed that some subjects who were non-tolerant to lens wear had variations in their tear protein profiles compared to tolerant subjects. Conclusion : These preliminary results demonstrate that clinical and biochemical tear profiles can be used to differentiate subjects with good lens wear tolerance from those who may be non-tolerant to lens wear.     

Specular microscopic follow-up of corneal grafts for pseudophakic bullous keratopathy

Pseudophakic bullous keratopathy (PBK) has become the leading indication for penetrating keratoplasty. In our initial fifty patients having keratoplasty for PBK there was gradual loss of clear grafts in patients with retained intraocular lenses (IOLs). Specular microscopy was performed on donor tissue, and periodically postoperatively, for 130 grafts for PBK. The highest cell loss at one year was in eyes with retained iris support (39.2%) or anterior chamber (37.2%) IOLs. Cell loss in grafts with removed iris support IOLs (21.3%) was significantly less. When iris support IOLs were exchanged for anterior chamber (AC) IOLs, the cell loss at one year (27.1%) was intermediate. We recommend that iris support IOLs be removed at keratoplasty. Exchange for an AC IOL should be considered depending on the visual needs of each patient. Removal of AC IOLs should be based on consideration of prior tolerance and position of the implant.     

框架镜与接触镜配戴者在近视激光手术前后的生活质量比较

目的:研究配戴框架镜与配戴角膜接触镜的近视患者接受准分子激光手术后生活质量的变化。方法:选取72例接受准分子激光近视手术的患者按术前矫正方式不同分为两组,配戴框架镜组50例,配戴角膜接触镜组22例,应用2007年中文版屈光矫正者生活质量量表(the quality of life impact of refractive correction,QIRC)在术前和术后3mo进行问卷调查。结果:(1)准分子激光近视手术后配戴框架镜组的生活质量(术后42.29±4.90,术前39.30±5.16)和满意度评分(术后86.51±9.14,术前71.58±13.24)均高于术前,差异均有统计学意义(P<0.01)。增加显著的模块是视功能与身体机能(P<0.01);增加显著的条目包括夜间驾驶(P<0.01)、夜间户外活动(P<0.05)、强光下不戴太阳镜生活或工作(P<0.05)、游泳(P<0.01)、担心花费(P<0.01)、自我感觉(P<0.05)及自信(P<0.01)方面。晨起视物(P<0.05)方面评分则较术前显著减少。(2)准分子激光近视手术后配戴接触镜组的生活质量(术后42.32±5.95,术前41.26±5.21)评分与术前比较无显著差异(P>0.05),但满意度评分(术后87.14±10.64,术前73.77±21.26)较术前显著增加(P<0.01)。在社会活动模块(P<0.05)及游泳(P<0.01)、担心并发症(P<0.05)方面的评分显著高于术前。结论:配戴框架镜的近视患者在接受准分子激光术后生活质量和对矫正方式的满意度明显提高,在视功能、身体机能、运动等方面提高显著。配戴接触镜的近视患者在接受准分子激光术后生活质量与术前相比没有明显差别,但对矫正方式的满意度增加,在运动、对眼部健康和花费的担忧方面明显改善。     

Contact lens induced keratopathy: a severe complication extending the spectrum of keratoconjunctivitis in contact lens wearers

A 21-year-old woman developed bilateral keratoconjunctivitis from contact lens wear, which progressed to diffuse corneal scarring and vascularization after the patient refused to discontinue wearing contact lenses. The visual disturbance became so severe that a penetrating keratoplasty had to be performed in one eye for visual rehabilitation. Examination of the penetrating keratoplasty specimen disclosed destruction of Bowman's membrane throughout the superior half of the cornea, which was replaced by a fibrous scar that was only midly chronically inflamed. Deep vascularization occurred within the stroma. This case represents an extreme expression of a recently characterized syndrome consisting of conjunctival and corneal changes in patients who may be allergic to contact lenses or the solutions used in conjunction with their care. In the milder end of the spectrum, there is superior epibulbar conjunctival injection with associated tarsal injection, and a mild superficial punctate keratopathy without filaments. Some earlier workers have termed this syndrome a variant of superior limbic keratoconjunctivitis in association with contact lens wear, but this leads to confusion with Theodore's classical superior limbic keratoconjunctivitis, to which the present entity bears no etiologic relationship; it also fails to show many of the findings of Theodore's disease. In mild cases, we would recommend the term contact lens-induced keratoconjunctivitis, and in the more severe cases, such as demonstrated by our patient, we would suggest the term contact lens-induced keratopathy.