Queratouveítis y conjuntivitis causadas por Euphorbia ingens. Revisión de un caso

Euphorbia ingens is a ubiquitous plant who has a milky sap. It can accidentally harm human's eye by its caustic nature, causing conjunctivitis, keratitis, uveitis, anterior staphyloma and corneal scarring in untreated patients. We present the case of a patient whose eye came into contact with the milky sap. He suffered conjunctivitis, corneal epithelial defect and uveitis. After intensive treatment, his eye made a complete recovery. We recommend gloves and protecting glasses before handling these types of plants.     

Euphorbia lactea sap keratouveitis: case report and review of the literature

PURPOSE: To describe a case of Euphorbia lactea sap keratouveitis and to review all reported cases of ocular toxicity caused by Euphorbia species. METHODS: Case report and review of literature. RESULTS: A 79-year-old woman presented 34 hours after she felt some sap of an E. lactea plant spray into her right eye. Visual acuity was counting fingers at 1 m. Examination revealed ciliary injection, 90% corneal epithelial defect, marked stromal edema with Descemet folds, and anterior-chamber flare with a 1-mm hypopyon. There was no vitreitis, and funduscopy was unremarkable. No foreign body was seen on B scan ultrasound or computed tomography scan of the orbits. Corneal scraping excluded bacterial and herpetic keratitis. Intensive topical antibiotic therapy was started with cephalothin 5% and gentamicin 0.9%, and the pupil was dilated with atropine. Topical steroids were started once the epithelial defect had healed. Examination 11 weeks after the injury revealed minimal subepithelial corneal haze and marked improvement in visual acuity. CONCLUSIONS: To the best of our knowledge, this is only the third reported case of E. lactea sap keratouveitis. The clinical course of E. lactea sap keratouveitis is compared with that reported for other Euphorbia species.     

PV角膜接触镜的治疗应用观察

目的:评估连续过夜配戴博士伦PV接触镜的治疗应用的指征与疗效。方法:非随机选用中山眼科中心的门诊与住院病例29例31只眼,包括需要缓解疼痛与刺激症,保护角膜和促进角膜创面愈合等病例。采用PV镜片连续过夜配戴治疗的同时,根据眼病性质、局部适当给予抗生素或人工泪液,定期检查或询问疼痛缓解情况、眼部改变、镜片的配适状态、镜片沉淀物以及眼部并发症。结果:病例共29例(31只眼),观察时间3～57d。平均20.9d,眼病包括大泡性角膜病变(6例6只眼),角膜炎合并小穿孔或后弹力层膨出5例(5只眼),化学烧伤上皮缺损6例(7只眼),角膜移植术或创伤缝线刺激3例(3只眼),丝状角膜炎3例(3只眼),角膜上皮糜烂2例(3只眼),反复性角膜上皮剥脱症1例(1只眼),角膜板层裂伤与上皮缺损1例(1只眼),外伤性白内障摘除术后持续上皮溃疡1例(1只眼),角膜缘移植联合羊膜移植术后1例(1只眼)。用于缓解疼痛与刺激症为目的者21例(22只眼),疼痛完全缓解或部分缓解达100%。促进角膜愈合者20例(22只眼);完全治愈15例(16只眼)占72.7%,部分改善者4例(5只眼)占22.7%。绷带保护角膜21例(23只眼),其中20例22只眼(95.7%)均有满意的保护作用,仅1例因配适不良无效。结论:PV角膜接触镜对于多种角膜病、眼表病、及角膜术后角膜保护、促进角膜愈合和缓解疼痛刺激等有显著疗效;镜片具有高透氧性能及抗沉淀性好,可大大减少眼部合并症发生的危险,这种新型的镜片可作为理想的首选的治疗性应用镜片。     

亲水角膜接触镜治疗眼前段术后持续性角膜上皮缺损疗效

目的:探讨高亲水性软性角膜接触镜治疗眼前段术后持续性角膜上皮缺损的效果。方法:回顾性病例分析,回顾2011-01/2013-06我院行眼前段术后出现持续性角膜上皮缺损患者28例28眼。采取常规治疗2wk后角膜上皮持续不愈,予高亲水性软性角膜接触镜,至角膜上皮完全愈合后摘镜,同一软镜持续佩戴不超过3wk,否则需更换新镜。随诊观察6mo,主要观察指标:角膜上皮愈合情况、角膜荧光素钠染色情况及眼部症状改善情况。结果:其中治愈21眼(75.00%),显效5眼(17.86%),有效2眼(7.14%),无无效病例,总有效率100.00%。25例(89.29%)眼部不适症状在2d内基本缓解,3例(10.71%)眼部不适症状在1wk内缓解;6例(21.43%)在佩戴3wk内上皮愈合,13例(46.43%)在佩戴6wk内愈合,7例(25.00%)在佩戴9wk内修复,2例(7.14%)佩戴超过12wk,角膜上皮较前修复。均无继发感染迹象。观察6mo无明显复发迹象。结论:高亲水性软性角膜接触镜能明显促进眼前段术后持续性角膜上皮缺损的修复,同时迅速有效缓解各种伴随的眼部刺激症状。     

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.     

前节OCT辅助准分子激光治疗性角膜切削术治疗真菌性角膜溃疡

目的 评价前节OCT辅助准分子激光治疗性角膜切削术(excimer laser phototherapeutic,PTK)治疗真菌性角膜溃疡的临床效果.方法 回顾性分析已确诊为真菌性角膜溃疡且应用局部和全身抗真菌药物治疗7d后无效或病情加重的24例(24眼)患者,角膜溃疡深度均未超过1/3角膜厚度,将患者分为两组,治疗组接受前节OCT辅助的PTK治疗,共14例(14眼),对照组采用角膜病灶板层切除手术治疗,共10例(10眼).随访至少6个月.记录治疗前后最佳矫正视力(best corrected visual a-cuity,BCVA)、角膜厚度、共焦显微镜检查情况.观察术后角膜上皮修复时间、治疗时间及并发症情况.结果 两组术后BCVA均较术前明显提高,差异均有统计学意义(均为P＜0.01),治疗组BCVA提高程度明显优于对照组,差异有统计学意义(P＜0.05).治疗组术后治疗持续时间为(19.43±5.68)d,短于对照组的(34.40±5.38)d,差异有统计学意义(P＜0.05).治疗组术后剩余角膜厚度与对照组相比差异无统计学意义(P＞0.05).共焦显微镜检查亦治疗组术后残余菌丝较对照组明显减少.治疗组术后上皮修复时间为(4.00±1.11)d,短于对照组的(6.20±1.39)d,差异有统计学意义(P＜0.05).随访期内,治疗组术后无一眼复发,对照组术后0.5a有3眼复发,1眼药物控制有效,另2眼病情加重,进一步行角膜移植手术.结论 前节OCT辅助PTK治疗真菌性角膜溃疡可以有效清除病灶、加速上皮愈合,为治疗早期浅层真菌性角膜溃疡提供了一个全新的选择.     

Implantation of preserved human amniotic membrane for the treatment of shield ulcers and persistent corneal epithelial defects in chronic allergic keratoconjunctivitis

PURPOSE: To determine whether amniotic membrane implantation is a safe and effective alternative treatment for shield ulcers and persistent corneal epithelial defects associated with ulcers in chronic allergic keratoconjunctivitis (vernal or atopic keratoconjunctivitis). METHODS: Amniotic membrane implantation was performed in four consecutive patients with persistent corneal epithelial defects or vernal plaques unresponsive to conventional medical treatment lasting an average of 18 weeks. Surgery was done under general anesthesia using amniotic membrane as a therapeutic contact lens. RESULTS: A significant decrease in symptoms and complete reepithelialization of the corneal ulcers were observed in all cases within the first 7 days. These remained stable during a mean follow-up of 12 weeks, with no intraoperative or postoperative complications. Early detachment occurred in all cases with no negative consequences on ulcer healing. CONCLUSION: Patients with severe chronic allergic keratoconjunctivitis derive benefits from amniotic membrane implantation used as a therapeutic contact lens in the treatment of persistent corneal epithelial defects and vernal plaques unresponsive to conventional medical treatment.     

Keratouveitis caused by sap of Euphorbia myrsinites plant

BACKGROUND: Euphorbia plants grow in many gardens. Their milky latex is, however, a strong irritant which may induce various ocular lesions from keratoconjunctivitis to severe uveitis. HISTORY AND SIGNS: A 86-year-old woman developed a unilateral severe anterior chamber inflammation associated with descemtic folds after direct contact with sap of Euphorbia. Visual acuity was limited to counting fingers. Her eye was operated from filtering surgery ten years previously. The patient was closely followed to rule out the diagnosis of bacterial endophthalmitis. THERAPY AND OUTCOME: Symptoms progressively resolved after topical administration of 3 mg/mL ofloxacine and 1 % prednisolone acetate. CONCLUSIONS: Euphorbia sap toxicity may take different forms from keratoconjunctivitis to severe uveitis. Euphorbia sap-induced uveitis should be kept in mind when the patient has seen in contact with freshly cut plants.     

Boston keratoprosthesis restoring vision in an unusual case of end-stage limbal stem cell deficiency following exposure to Euphorbia latex

We report the functional outcome of a patient who had undergone Boston keratoprosthesis type I for extensive ocular surface damage caused by latex of Euphorbia. The milky sap or latex of the Euphorbia plant is highly toxic and an irritant to the skin and eye. Damage to the eye ranges from mild to severe corneal edema, epithelial defects, anterior uveitis, secondary elevated intraocular pressure and, rarely, limbal stem cell deficiency with corneal neovascularization. A restrospective review was conducted of this patient for more than 1 year. During this period he was given subconjunctival bevacizumab injection to regress the corneal vascularization without much benefit, before finally performing Boston keratoprosthesis type I. The patient was evaluated periodically for both anatomical and visual outcome. At the end of 1-year follow-up the keratoprosthesis is well retained with a best-corrected visual acuity of 20/40 in the affected eye.     

Epithelial healing and ocular discomfort after photorefractive keratectomy in children

OBJECTIVE: To document the rate of healing of the corneal epithelial defect created by photorefractive keratectomy (PRK) and the degree of discomfort experienced by children treated with PRK. SETTING: Baylor College of Medicine, Texas Children's Hospital, Houston, Texas, USA. METHODS: Ten patients between 3 and 10 years of age were treated with PRK for severe anisometropia. All had anisometropic amblyopia refractory to conventional therapy with glasses or contact lenses and occlusion therapy. The size of the corneal epithelial defect was documented daily until the defect healed completely. Postoperative discomfort was documented daily using a pain-assessment scale until the epithelial defect healed completely. RESULTS: Two children were treated with PRK for hyperopic anisometropia; the rest were treated for myopic anisometropia. Cumulatively, the corneal epithelium had healed completely by day 3 in 6 patients (60%), by day 4 in 9 patients (90%), and by day 5 in all patients. The mean healing time was 3.5 days. Patients experienced mild discomfort on the day of surgery and on the first postoperative day. They had minimal pain on day 2. After day 2, no patient reported pain or other discomfort. CONCLUSIONS: The corneal epithelial defect created by PRK healed promptly and was associated with minimal postoperative discomfort in children treated with the protocol described.     

绷带镜治疗持续性角膜上皮缺损的临床观察

目的:通过博士伦PureVision纯视角膜接触镜在眼科的应用,观察绷带镜在持续性角膜上皮缺损中的应用及临床效果,评估绷带镜在眼表疾病中的治疗价值及意义.方法:非随机选取持续性角膜上皮缺损患者30例38眼,配戴绷带镜3d ～ 3mo,观察配戴前后各时段角膜刺激症状、角膜上皮愈合情况、视力及不良反应情况.结果:所选患者30例38眼中完全缓解23眼(61％),部分缓解11眼(29％),有效率89％.促进角膜上皮愈合:完全愈合11眼(29％),部分愈合21眼(55％),有效率84.2％;视力提高22眼,有效率58％.结论:绷带镜能有效缓解角膜上皮缺损引起的疼痛,保护角膜,维持局部湿润度,加速持续性角膜上皮病变的愈合,缩短病程,安全、有效,可广泛应用于临床,在基层医院推广.     

Anterior amorphous corneal opacity and corneal thinning

PurposeTo present the clinical features of four cases with bilateral anterior amorphous corneal opacity.MethodsA retrospective study in four patients with bilateral anterior amorphous corneal opacity was conducted. Examinations included visual acuity, keratometry, slit-lamp biomicroscopy, confocal microscopy, anterior segment optical coherence topography, and histology.ResultsThree female and one male patients (mean age, 52.3 ± 8.9 years) showed bilaterally oval, amorphous sheetlike corneal opacities with central depression and thinning. Superior limbal opacities were observed in two of these patients. The best-corrected visual acuity ranged from 20/50 to 20/400, and the mean of the keratometry was 39.81 ± 3.97 D (diopters). They had mild dry eyes. The anterior segment optical coherence topography demonstrated hyporeflective abnormalities in the anterior depressed stroma in these four patients. Confocal microscopy revealed large round cells at the epithelial layer in one patient, and amorphous opacities with some strand-shaped opacities in the anterior stroma in all four patients. The mean of the corneal endothelial cells density in the eight eyes was 1521 ± 402 cells/mm². Central corneal stromalysis occurred in three patients, and descemetocele developed in two eyes. One patient received penetrating keratoplasty and two underwent lamellar keratoplasty. The histology of the corneal specimen revealed edematous basal epithelial cells, focal collagen disorganization in the thin stroma, and wartlike excrescences in a thickened Descemet's membrane.ConclusionAnterior amorphous corneal opacity is a rare keratopathy and may be one kind of rare corneal degeneration or dystrophy. Corneal stromalysis may occur in hyporefrective amorphous opacities and progress to descemetocele.     

Topical mitomycin-C for subepithelial fibrosis after refractive corneal surgery

OBJECTIVE: To determine the effectiveness of mitomycin-C (MMC), 0.02%, in preventing recurrence of corneal subepithelial fibrosis after debridement and/or keratectomy in patients who have undergone refractive corneal surgery. DESIGN: Noncomparative case series. PARTICIPANTS: Eight eyes of five patients with corneal subepithelial fibrosis who had previously undergone radial keratotomy (n = 4) or photorefractive keratectomy (n = 4). INTERVENTION: All eyes underwent epithelial debridement followed by a single intraoperative application of MMC (0.02%) for 2 minutes followed by saline irrigation. The eyes were then patched, or a bandage contact lens placed until epithelial healing was complete. MAIN OUTCOME MEASURES: Corneal clarity and best-corrected visual acuity (BCVA). RESULTS: In all cases, the cornea remained clear with no recurrence throughout the follow-up period (6-25 mos., mean, 13.8 mos). No adverse reactions were reported. BCVA improved in all cases. CONCLUSIONS: Subepithelial fibrosis can be a visually disabling condition after refractive corneal surgery. Topical application of MMC (0.02%) may be a successful method of preventing recurrence of subepithelial fibrosis after debridement.     

生物羊膜联合治疗性角膜软接触镜治疗角膜溃疡

目的:探讨角膜溃疡患者行生物羊膜联合治疗性角膜软接触镜的治疗效果及可行性。方法:对33例35眼角膜溃疡患者进行削除病变组织,在植床平铺与溃疡面大小相仿生物羊膜(溃疡较深行多层羊膜覆盖填塞),将稍大于溃疡灶的外层生物羊膜与周围正常角膜组织间断缝合,术后第2d配戴治疗性角膜软接触镜,并针对不同病因的角膜溃疡点用治疗性眼药水。结果:所有患者1～2d内恢复前房,1wk左右局部刺激症状明显好转,溃疡平均愈合时间30～45d,5例患者见新生血管长入,角膜不同程度的瘢痕形成,2例角膜溃疡前房反复消失,后行穿通性角膜移植。治疗后视力均有不同程度的提高。结论:此方法能有效修复角膜溃疡组织,为后期角膜移植创造良好的局部条件。     

Sloughing of corneal epithelium and wound healing complications associated with laser in situ keratomileusis in patients with epithelial basement membrane dystrophy

PURPOSE: To report sloughing of corneal epithelium during laser in situ keratomileusis and subsequent wound healing complications in patients with epithelial basement membrane dystrophy. METHODS: In a retrospective study, the surgical procedures, postoperative course, and visual acuities of 16 eyes of nine patients with epithelial basement membrane dystrophy who underwent laser in situ keratomileusis complicated with epithelial sloughing at three centers were reviewed. The mean follow-up period was 23 weeks (range, 4 to 52 weeks). RESULTS: In 13 (81%) of 16 eyes with epithelial basement membrane dystrophy, epithelial sloughing occurred during laser in situ keratomileusis. In eight of the 13 eyes, epithelial growth beneath the flap was observed. The flap was lifted and the interface epithelium scraped in six eyes. Flap melt or keratolysis occurred in four eyes. At the last follow-up visit, 13 of 16 eyes had an uncorrected visual acuity of 20/30 or better, and all eyes had a best-corrected visual acuity of 20/30 or better. CONCLUSIONS: Patients with epithelial basement membrane dystrophy have poorly adherent corneal epithelium and are predisposed to epithelial sloughing during the microkeratome pass of laser in situ keratomileusis. This may lead to flap distortion, interface epithelial growth, flap keratolysis, and corneal scarring. It is not recommended that laser in situ keratomileusis be performed in patients with classic, symptomatic epithelial basement membrane dystrophy. In patients who present with mild and asymptomatic epithelial basement membrane dystrophy, laser in situ keratomileusis should be performed with caution, or photorefractive keratectomy may be the preferred refractive procedure.     

Corneal hazards in use of Simmons shell

A Simmons tamponade shell was used in 10 cases of post-trabeculectomy overfiltration leading to shallow (iridocorneal touch) or flat anterior chamber. The Simmons shell was an unqualified success in only three cases. Corneal abscess (one case) and corneal abrasion/epithelial loss (four cases) necessitated premature removal of the shell. Three of the patients with corneal abrasions had a formed anterior chamber at the time of shell removal but this shallowed again within 12 hours. Two of these required surgical reformation of the anterior chamber and one reformed spontaneously. Air entrapment causing corneal dessication was probably responsible for the abrasion/epithelial loss. The patient who developed a corneal abscess was grossly malnourished. Use of the Simmons shell needs close monitoring and it should be removed at the first sign of corneal toxicity (abrasion/epithelial loss). Extreme care is necessary in malnourished cases.     

Amniotic membrane transplantation in severe corneal epithelial diseases. Preliminary results

PURPOSE: To evaluate amniotic membrane transplantation (AMT) in severe corneal epithelial diseases. METHODS: Amniotic membrane transplantation was performed in 14 eyes of 14 patients from four groups: A, five severe ocular burns; B, four cases of cicatricial keratoconjunctivitis; C, three persistent epithelial defects after penetrating keratoplasty; D, two cases of pseudophakic bullous keratopathy. Five patients underwent AMT alone; two patients underwent AMT combined with limbal transplantation; the other three patients had limbal transplantation performed before AMT. Eight patients required combined penetrating keratoplasty. Patients with corneal stable reepithelialization, no corneal neovascularization, and no recurrence of the initial pathology were considered successful. RESULTS: The mean follow-up was 7+/-3 months. All but three patients underwent corneal reepithelialization within 6 weeks of AMT, with a mean healing time of 31+/-23 days. The success rate was 75% at 6 months (Kaplan-Meier method). Three of four procedures in group B failed. In eight patients, visual acuity improved, in one it worsened, and in the last five patients it remained unchanged. Visual acuity increased by an average of 7+/-9 lines. CONCLUSION: AMT is a useful technique for ocular surface reconstruction, especially in association with limbal transplantation. It could also improve the prognosis of penetrating keratoplasty in patients with severe corneal conditions.     

个性化治疗角膜穿孔的临床观察

目的:探讨应用不同手术方法治疗角膜穿孔的适应证及疗效。方法:采用非随机回顾性系列病例研究,选择2005-10/2007-08在沈阳军区总医院住院的20例20眼角膜穿孔患者,分别选择穿透性角膜移植术(6例,30%)、眼前节重建术(4例,20%)、板层角膜移植术(6例,30%)、羊膜移植术(4例,20%),术后随访6～30mo,观察患者穿孔愈合情况、术后视力、角膜植片透明度及并发症。结果:所有病例均在手术后封闭穿孔。术后增视者有16眼,手术增视率为80%;穿透性角膜移植者植片7例透明,1例半透明,1例混浊。眼前节重建术植片半透明或混浊(Ⅱ期行新鲜角膜移植)。板层角膜移植术3例透明,3例混浊。并发症:虹膜粘连4例;继发性青光眼3例;排斥反应2例;原病复发1例;双前房1例。结论:根据角膜穿孔的原因、位置、大小等综合因素,对角膜穿孔患者灵活选用不同手术方法,能够达到保存眼球完整性、增进视力的要求。     

Amniotic membrane transplantation for ocular surface reconstruction

AIMS: To evaluate the efficacy of amniotic membrane transplantation (AMT) for ocular surface reconstruction. METHODS: 10 consecutive patients who underwent AMT were included. The indications were: group A, cases with persistent epithelial defect after corneal abscess (n = 1), radiation (n = 1), or chemical burn (n = 3); group B, cases with epithelial defect and severe stromal thinning and impending or recent perforation, due to chemical burn (two patients, three eyes) or corneal abscess (n = 2); group C, to promote corneal epithelium healing and prevent scarring after symblepharon surgery with extensive corneo-conjunctival adhesion (n = 1). Under sterile conditions amniotic membrane was prepared from a fresh placenta of a seronegative pregnant woman and stored at -70 degrees C. This technique involved the use of amniotic membrane to cover the entire cornea and perilimbal area in groups A and B, and the epithelial defect only in group C. RESULTS: The cornea healed satisfactorily in four of five patients in group A, but the epithelial defect recurred in one of these patients. After AMT three patients underwent limbal transplantation and one penetrating keratoplasty and cataract extraction. In group B amniotic membrane transplantation was not helpful, and all cases underwent an urgent tectonic corneal graft. Surgery successfully released the symblepharon, promoted epithelialisation and prevented adhesions in the case of group C. CONCLUSION: AMT was effective to promote corneal healing in patients with persistent epithelial defect, and appeared to be helpful after surgery to release corneo-conjunctival adhesion. Most cases required further surgery for visual and ocular surface rehabilitation. Amniotic membrane used as a patch was not effective to prevent tectonic corneal graft in cases with severe stromal thinning and impending or recent perforation.     

Effects of diabetes on anterior ocular structure and function

Diabetes is a systemic disease that affects multiple organs including the entire eye. Although diabetic retinopathy is the main cause for vision loss in patients with diabetes, many anterior segment abnormalities have been described, including structural changes in the tear film, the conjunctiva, and the corneal epithelial and endothelial cells. Functional alterations in corneal wound healing, corneal sensitivity, and recovery from contact lens-induced edema also accompany diabetes, and this raises the issue of whether contact lens wear may be contraindicated in these patients. To address this issue, eye care providers must be able to recognize the effects of diabetes on the anterior ocular surface, understand the biochemical mechanism(s) believed to be responsible for these alterations, and determine the relevance of observed changes with respect to contact lens wear.