Comparison of effectiveness of silicone hydrogel contact lens and hydrogel contact lens in patients after LASEK

AIM: To conduct a comparative study of effectiveness of silicone hydrogel contact lens and hydrogel contact lens, which are used in patients after laser-assisted subepithelial keratomileusis (LASEK). METHODS: Sixty-three patients (121 eyes) with a spherical equivalent ≤-5.0 D were chosen after undergoing LASEK in 2012 at Guangdong General Hospital. They were randomly divided into 2 groups. The silicone hydrogel group included 32 cases (61 eyes) that wore silicone hydrogel contact lenses for 4-6d after the operation, while the hydrogel group included 31 cases (60 eyes) who wore hydrogel contact lenses for 4-6d after the operation. Patients’ self-reported postoperative symptoms (including pain, photophobia, tears, and foreign body sensation) were evaluated. The healing time of the corneal epithelium, the visual acuity of patients without contact lens after epithelial healing, and the incidence of delayed corneal epithelial shedding were also assessed. The follow-up time was 1mo. RESULTS: Postoperative symptoms were milder in the silicone hydrogel group than in the hydrogel group. There were significant differences in pain, foreign body sensation, and photophobia between the 2 groups (P<0.05), although there was no significant difference in postoperative tearing (P>0.05). The healing time of the corneal epithelium in the silicone hydrogel lens group was markedly shorter than that in the hydrogel group (4.07±0.25 vs 4.33±0.82d, t=2.43, P=0.02). Visual acuity without contact lenses after healing of the corneal epithelium was better in the silicone hydrogel group compared with the hydrogel group (χ2=7.76, P=0.02). There was no significant difference in the occurrence of delayed corneal epithelial shedding between the 2 groups (P>0.05). CONCLUSION: Patients with LASEK using silicon hydrogel contact lenses had less discomfort and shorter corneal epithelial healing time compared with those using hydrogel contact lenses, suggesting that silicon hydrogel contact lenses may be considered to be a better choice of bandage contact lens after LASEK.     

Clinic study on silicone hydrogel contact lenses used as bandage contact lenses after LASEK surgery

AIM: To compare the clinical performance of two types of silicon hydrogel contact lenses used as bandage lenses after LASEK surgery. METHODS: A prospective, double-masked study was conducted on 42 eyes of 21 patients who received binocular LASEK surgeries. The interocular difference in spherical equivalent power was less than -1.50D. Patients were randomly assigned to wear Galyfilcon A (Lens A) bandage contact lens in one eye and Balafilcon A (Lens B) in the fellow eye after the surgery. The responses to a subjective questionnaire on comfort of wearing, corneal epithelial status, conjunctival hyperemia, limbal neovascularization, lens fitting and contact lens debris were assessed 1 and 5 days postoperatively. Corneal endothelium was assessed before and 5 days after the surgery upon bandage lens removal. RESULTS: There was no difference between the two groups in terms of conjunctival hyperemia, limbal neovascularization, contact lens fitting, corneal epithelial status, corneal endothelium cell density (CD) and endothelium cell size (CS) at any postoperative visit. Complaints of discomfort, including foreign body sensation, pain and intolerance were statistically more among Lens B wearers at any postoperative visit (P<0.05). Lens B appeared to attract much more debris than Lens A at the 5-day post-operative follow-up visit (P<0.01). CONCLUSION: The two types of silicon hydrogel lenses investigated in this study demonstrated similar clinical performance in terms of corneal responses and lens fitting. However, Lens A showed a better performance in terms of comfort of wearing and deposit resistance.     

Hydrogel lens wettability and deposition in vivo

Background : Wearing a hydrogel contact lens disrupts tear film stability, resulting in a low non-invasive surface drying time (NISDT) on the lens front surface. Reduced wettability causes deposit formation, reducing the quality of vision and lens comfort. This investigation determined the effect of commercially available HEMA-based materials on pre-lens tear film stability and deposition. Methods : Twenty patients in a randomised, double blind study wore four lenses for eight hours. These lenses were Tefilcon, Polymacon (Group I lenses), Vifilcon A and Etafilcon A (Group IV lenses). Non-invasive surface drying time (NISDT) was measured for each lens type after 10 minutes, one hour, four hours and eight hours wear. Lenses were then removed and examined by scanning electron microscopy. Results : NISDT decreased significantly (p < 0.05) over the eight-hour wear period for all lens types. Group IV lenses showed a slightly, but not clinically significantly, higher NISDT compared to Group I lenses. A greater number of deposits was seen on Vifilcon A and Polymacon compared to Etafilcon A and Tefilcon lenses. Conclusions : Wear decreases lens wettability over eight hours, irrespective of lens type. Higher wettability was seen with Group IV lenses, although the increase was not clinically significant. Wettability was not correlated with the formation of discrete deposits. Deposit formation depends on the composition of the lens base material, its ionic charge, surface topography, water content and wearers' ocular characteristics.     

无晶状体眼角膜接触镜的配戴

我们对无晶状体眼患者所存在的问题,特点,及所需要的矫正治疗进行了综合分析。我们发现角膜接触镜对于无晶状体眼患者的矫正有很大的帮助,较之其他的矫正方法存在着独特的优势。本文着重从无晶状体眼患者角膜接触镜矫正治疗的方式选择,角膜接触镜的设计以及所产生的并发症等方面进行了阐述。     

Bacterial colonization of hydrogel disposable contact lenses

AIM: To determine the rate of bacterial colonization in hydrogel disposable contact lenses and solutions and to identify the contaminating organisms. METHODS: A cross sectional study with purposive sampling was carried out. One hundred hydrogel contact lenses were collected from wearers among undergraduate students of Health Campus, University Sains Malaysia. All lenses and storage solutions were sent for microbiological culture and gram staining. RESULTS: The majority of study participants were females (98%). The mean age was 21.36±1.63 years. Forty-one subject participants (82%) showed positive bacterial colonization of the lenses. From storage solutions 32% yielded positive colonization by bacteria. The most common organisms were coagulase negative staphylococcus, Staph aureus and streptococci while Pseudomonas sp. and Serratia sp. were isolated more frequently from contact lenses. CONCLUSION: Contact lens wearing is potentially dangerous as a result of high rate of bacterial colonization of the lenses and its storage solutions. Extreme precaution and adherence to strict hygienic practice is recommended during lens handling and wearing.     

Comfort of fenestrated hydrogel lenses

A controlled, double-masked, randomized study was conducted on ten subjects to determine the effect of fenestration size on the initial comfort of hydrogel contact lenses. Four fenestrated lenses were tested, each lens containing four mid-peripheral fenestrations of the same size. The diameter of the fenestrations used in the four lenses ranged from 0.39 to 0.96 mm. An unfenestrated lens was also tested. All lenses were made of HEMA and were ordered with the following specifications: -3.00 D, 14.0 mm diameter, 8.4 mm back central optic radius and 0.06 mm centre thickness. There was a significant negative correlation between comfort and fenestration size, indicating that larger fenestrations are less comfortable. Even the lens with the smallest fenestrations (0.39 mm) was significantly less comfortable than the unfenestrated lens. The implication of this finding is that fenestrations may not be clinically efficacious in view of the poor comfort (and presumably increased mechanical effect of the fenestration edges on the tarsal conjunctiva) of fenestrated lenses.     

抛弃型水凝胶接触镜的细菌定植

目的:确定抛弃型水凝胶接触镜及其护理液细菌定植的比率,并确定污染的病原体。方法:按目的抽样进行横断面研究。从马来西亚Sains大学健康校园的本科学生接触镜配戴者中收集100片水凝胶接触镜。所有的镜片和护理液均送微生物培养和革兰氏染色。结果:大多数的研究参与者为女性(98%)。平均年龄21.36±1.63岁。41片接触镜(82%)呈现阳性细菌定植,32%的护理液可见阳性细菌定植。最常见的病原体是凝固酶阴性葡萄球菌、金黄色葡萄球菌和链球菌,而在接触镜中能更频繁地分离出假单胞菌和沙雷氏菌。结论:配戴接触镜有导致镜片和护理液细菌定植的潜在危险。建议在镜片护理和配戴过程中采取最大程度的预防措施并严格遵守卫生做法。     

绷带型角膜接触镜在上睑下垂术后早期的应用价值

目的　探讨上睑下垂术后早期应用绷带型角膜接触镜的临床效果。方法　将先天性上睑下垂矫正术后眼睑闭合不全患者２１例（３２眼）随机分为Ａ组（戴镜组）和Ｂ组（传统组）。２组均按常规方法行额肌肌瓣悬吊术,术后Ａ组均连续配戴绷带型角膜接触镜,每１４ｄ更换１次;Ｂ组均根据传统的方法滴滴眼液和涂眼膏,术前及术后３ｄ、７ｄ、１个月、３个月观察角膜荧光素染色、泪膜破裂时间、泪液分泌试验、患者主觉症状等以评价治疗效果。结果　Ａ组和Ｂ组术后各时间段泪液分泌量均无明显改变,但两组在术后早期均出现了角膜上皮染色,染色点较术前增加,术后３ｄ角膜荧光染色评分明显增加,但两组间差异无统计学意义（Ｐ＝０．６９８）;术后７ｄ、１个月荧光染色评分仍继续增加,且两组间差异有统计学意义（Ｐ＝０．０３２、０．０１０）;术后３个月角膜染色基本消失,两组间差异无统计学意义（Ｐ＝０．５５７）。泪膜破裂时间术前无明显差异,术后３ｄ两组均较术前减少,术后７ｄ、１个月Ａ组较前逐渐变长,Ｂ组变化不明显,两组间差异有统计学意义（Ｐ＝０．０４、０．０２、０．０１）,术后３个月两组均有所恢复,组间差异无统计学意义（Ｐ＝０．７４３）。主觉症状评分术前两组间差异无统计学意义（Ｐ＝０．８３６）,术后３ｄ患者主觉症状明显增加,但Ａ组症状明显较Ｂ组减轻,两组差异有统计学意义（Ｐ＝０．０３５）;术后７ｄ、１个月两组主觉症状均有所减轻,但两组差异仍有统计学意义（Ｐ＝０．０３１、０．０１７）;术后３个月两组主觉症状逐渐消失,组间差异无统计学意义（Ｐ＝０．６９２）。结论　上睑下垂矫正术后早期配戴硅水凝胶角膜接触镜,不仅可使患者早期用眼,而且可促进患者泪膜稳定,减轻眼部不适感,降低发生暴露性角膜炎的风险。     

Mechanisms of dryness in soft lens wear— role of BUT and deposits

Background: The symptom of dryness in hydrogel lens wear is common but its origins remain poorly understood. To assess the theory that anterior lens surface interactions are responsible for the sensation of dryness during lens wear, 50 contact lens wearers were evaluated. Method: The Efron comfort scale was used to divide the group into subjects with comfortable lenses (26 control subjects) and those who were symptomatic (24 study subjects). The two groups were matched for gender, age, lens age, lens water content, lens wear experience and wearing environment. The only difference between the groups was that the non-symptomatic wearers had a greater wearing time (ANOVA, p = 0.005). Lens deposits and pre-lens tear thinning time (PLTTT) were assessed for each group. Results: The median PLTTT for the control group was three seconds (25th percentile, two seconds; 75th percentile five seconds); the study group had a median PLTTT of 3.5 seconds (25th percentile, 1.5 seconds; 75th percentile, four seconds). There was no significant difference in lens deposits and PLTTT between the comfortable and uncomfortable lens wearing groups, in particular, subjects with a short PLTTT (for example, less than four seconds) could still be comfortable. However, there was a significant inverse correlation between the grade of lens deposits and PLTTT (Spearman rank correlation, p = 0.01); a positive correlation between the grade of lens deposits and lens age (Spearman rank correlation, p = 0.001). Conclusions: The findings suggest that pre-lens tear stability is not necessarily an influence on comfort. It may be that the source of soft lens discomfort arises more from the exposed bulbar conjunctiva than the interaction between anterior lens surface and the tarsal conjunctiva. (Clin Exp Optom 1995; 78: 5: 168–175)     

Contact Lenses for Drug Delivery

The majority of ocular medications are delivered to the eye topically, often in the form of a solution, or eye drop. Contact lenses could potentially also be used to deliver medications to the eye. Recently, progress has been made in developing a drug-eluting contact lens. Different designs have been proposed and several offer the hope of expanding the therapeutic armamentarium for eye care providers.     

Feasibility of multifocal intra‐ocular lens exchange and conversion to the bag‐in‐the‐lens implantation

Purpose: Our purpose was to evaluate the surgical outcome after intra‐ocular lens exchange in patients who presented impairing visual complaints after primary multifocal intra‐ocular lens (MIOL) implantation. In particular, the study was undertaken to look at the number of eyes that could be equipped with the bag‐in‐the‐lens (BIL) IOL after MIOL exchange. Methods: This series consisted of 30 eyes of 21 consecutive patients scheduled for MIOL exchange. In 15 out of the 30 eyes, IOL misalignment was measured on slit lamp anterior segment photo’s after defining the mathematical centres of the IOL optic, pupil and limbus. Results: Diffractive MIOL was more frequently explanted (25; 83%) when compared with refractive MIOL (4; 13%) and progressive optic IOL (1; 4%). In 21 out of the 30 eyes (70%) a bag‐in‐the‐lens could be implanted. In 7 out of the 30 eyes (23%), the capsule was not considered sufficiently stable to accommodate an IOL. An iris‐fixated IOL or a sulcus‐fixated IOL was then implanted. In 2 out of the 30 eyes (6%) the remaining capsular bag could accommodate a traditional lens‐in‐the‐bag only. Eyes that underwent Nd:YAG laser capsulotomy prior to the MIOL exchange needed anterior vitrectomy peroperatively (11 eyes; 37%). Visual acuity improved postoperatively in 13 out of the 30 eyes and remained stable in 17 out of the 30 eyes. Conclusions: Since the BIL technique requires a very well‐preserved capsular bag for the purpose of the IOL implantation, the success rate of BIL implantation after MIOL is a good indicator to evaluate the degree of difficulty to exchange MIOL.     

两种角膜绷带镜在LASEK术后配戴的临床观察

目的：评价两种角膜绷带镜 Senofilcon A 和 Balafilcon A 在准分子激光上皮下角膜磨镶术(laser-assisted subepithelial keratomileusis, LASEK)术后应用的临床安全性和有效性。方法：行 LASEK 患者38例76眼,术后38眼配戴senofilcon A 角膜绷带镜,38眼配戴 Balafilcon A,连续配戴7d。术后第3、7d 由患者对两眼主观症状(眼痛、异物感、流泪)进行评分。7d 摘镜后检查视力和角膜染色情况。结果：配戴两种镜片术后主观症状中眼痛感和流泪两眼存在差异,Senofilcon A 眼症状更轻,眼痛感在术后3、7d 两组比较差异有统计学意义(Z=-4.146,P=0.000;Z=-2.814,P=0.005)。流泪在术后3、7d 时两组比较差异有统计学意义为(Z=-2.309,P=0.021;Z=-3.276,P=0.001)。而干涩感在术后3、7d 时两组比较无统计学差异(Z =-0.447, P=0.655;Z =-0.966,P =0.334)。术后7d 摘除镜片后, Senofilcon A 眼视力优于 Balafilcon A 眼,差异有统计学意义( t =3.800,P =0.001)。两组摘镜后,角膜染色大多为1~2个象限的少量点染,对比有统计学差异( Z =-2.384,P=0.017)。
　　结论：Senofilcon A 以及 Balafilcon A 角膜绷带镜在 LASEK术后应用是安全有效的,Senofilcon A 对角膜上皮瓣的恢复更优些。     

Peripapillary retinal nerve fibre layer thickness measurement with SD-OCT in normal and glaucomatous eyes:distribution and correlation with age

AIM:To determine peripapillary retinal fiber layer thickness (RNFL) measured with spectral domain optical coherence tomography (SD-OCT) in normal and glaucomatous eyes in a large sample of exclusively white population and compare results with other similarly constructed studies.METHODS:Average, maximum, minimum and per quadrant RNFL thickness were measured in normal and glaucomatous Greek patients with a scanning laser ophthalmoscope (SLO)/SD-OCT device. The effect of age in normal RNFL thickness was also determined.RESULTS: A total of 278 normal (278 patients) and 67 glaucomatous (67 patients) eyes were included in the study. Average RNFL thickness was 114.8±13.3μm in normal and 92.1±18.5μm in glaucomatous eyes (P<0.001). In normal discs, superior quadrant was the thickest, followed by the inferior, nasal and temporal. Decline of normal RNFL thickness with age was statistically significant for average RNFL thickness (1.92μm per decade of life) and for the superior and inferior quadrants of the disc.CONCLUSION:SD-OCT peripapillary RNFL measurements can be used to distinguish between normal and glaucomatous eyes and establish normative databases, since normal disc measurements differ between different ethnic groups and between different SD-OCT devices.     

Hydrogen peroxide disinfection of hydrogel contact lenses: An overview

Many hydrogen peroxide systems have recently been introduced to the contact lens market. No two systems are identical, and practitioners are confronted with a great deal of information from the various solution companies. When considered en musse, this information is complex and often contradictory. Here, we review the principles of hydrogen peroxide disinfection and neutralization, and critically examine the major differences in the systems with a view to the development of guidelines for the safe and effective use of this disinfecting agent. Attention is drawn to a number of important issues which are yet to be resolved.     

Contact lens practice in Australia 1988–1989

Contact lens practitioners completed an annual survey of their prescribing patterns, usage of care solutions and attitudes to extended wear (EW). The survey period was July 1 1988 to June 30 1989 and the results were compared to those of previous, similar surveys. Many results were close to those in previous surveys, including the average number of pairs of lenses prescribed (95 new, 30 replacement), the proportion of contact lens fittings which were refits (40 per cent), the percentage of lenses prescribed which were soft (83 per cent) and the proportions of toric (soft 23 per cent, hard five per cent) and tinted (soft 39 per cent, hard 71 per cent) lenses prescribed. Results which differed markedly from previous surveys included the number of pairs of replacement lenses sold and the percentage of contact lens patients who were presbyopic. More than 90 per cent of lenses prescribed for EW were soft, although approximately 20 per cent of practitioners indicated that they would prefer to fit rigid gas permeable materials for EW. EW lenses were worn only on a true EW basis in six per cent of cases.     

Late in‐the‐bag intraocular lens dislocation in eyes with pseudoexfoliation syndrome

Purpose:  To assess preoperative features, frequency, surgical approaches and outcomes of late in‐the‐bag dislocation of posterior chamber intraocular lenses (IOLs) in eyes with pseudoexfoliation syndrome. Methods:  Seventy‐seven patients (81 eyes) were enrolled. Inclusion criteria were patients with pre‐existing pseudoexfoliation syndrome who underwent surgery for late in‐the‐bag IOL dislocation between March 2004 and April 2010. Medical records were reviewed. Data from before and after secondary surgery were analysed. Results:  Mean time between cataract extraction and secondary surgery for late in‐the‐bag dislocation of posterior chamber IOLs was 8.5 years. The increase in frequency within the reviewed period was statistically significant, ranging from six patients in the first year to 25 patients in the final year (p = 0.004). When surgical correction was performed within 1 month of referral, deterioration of the dislocation occurred in only one of 23 patients (4.3%). Complications, especially vitreous loss, occurred significantly more frequently during exchange surgery (n = 23) when compared with scleral suturing (n = 50) (p < 0.0001). After surgery, however, no differences in complications (p = 0.98) or best‐corrected visual acuity (p = 0.74) was found. In general, following secondary surgery, there was a statistically significant improvement in best‐corrected visual acuity (p < 0.0001). Conclusion:  The frequency of late in‐the‐bag dislocation of posterior chamber IOLs in eyes with pseudoexfoliation syndrome increased during the observation period. Our study suggests that surgical repair should not be delayed beyond 1 month and that scleral suturing is preferable to exchange surgery, because of less intraoperative complications.