Decreased keratocyte density and central corneal thickness in primary open-angle glaucoma patients undergoing treatment with topical prostaglandin analogues

Purpose:

To evaluate whether prostaglandin (PG) analogue use is associated with alterations in keratocyte density and central corneal thickness (CCT) in subjects with primary open-angle glaucoma (POAG).

Materials and Methods:

Thirty-five POAG patients treated with PG analogues for >2 years and 35 control subjects without glaucoma were included in this cross-sectional study. All subjects were underwent CCT measurements using ultrasound pachymetry. Keratocyte densities of each stromal layer were determined by in vivo confocal microscopy. Student''s t-test and Chi-square test were used for statistical evaluations. Correlations between keratocyte densities and CCT were analyzed using Pearson''s correlation analysis.

Results:

Keratocyte densities in each stromal layer were significantly lower in glaucoma patients receiving PG analogues as compared to those of controls (P < 0.001). The mean CCT was also lower in glaucoma patients (515.2 ± 18.8 μ) than control subjects (549.6 ± 21.1 μ, P < 0.001). A positive correlation between keratocyte densities in each stromal layer and CCT was observed in POAG patients.

Conclusions:

Long-term administration of topical PG analogues may adversely influence keratocyte densities and CCT. Further prospective studies are required clarify the relationship between PG analogues and their effects on the cornea.     

Effect of topical anaesthesia on corneal epithelial fragility

The effect of topical anaesthetics on human corneal integrity was assessed by measurement of the alterations they cause in corneal damage threshold. The anaesthetics investigated were 1.0% Amethocaine HCl, assessed immediately after instillation and after delays of 20 min and 60 min, and 0.5% Amethocaine HCl and 0.4% Benoxinate HCl, assessed 20 min after instillation. At 20 min after instillation of 1.0% Amethocaine HCl, the corneal damage threshold was significantly decreased. At other times for this anaesthetic, and for 0.5% Amethocaine HCl and 0.4% Benoxinate HCl, the corneal damage threshold was unaltered.     

Effect of topical mitomycin C on corneal endothelium

PURPOSE: To evaluate patients with ocular surface squamous neoplasia (OSSN) on treatment with topical mitomycin C (MMC) with regard to changes in corneal thickness and endothelial count. DESIGN: Prospective, nonrandomized, interventional series. METHODS: In this prospective evaluation, 25 patients with OSSN with different clock hours of involvement (range, one to eight), age varying from 19 to 76 years, were treated with topical MMC 0.04% in a cyclic manner. Preoperative corneal thickness measurement and endothelial cell density were obtained, and the tests were repeated after one, three, and six months of complete resolution. The fellow eyes of the same patients served as controls. RESULTS: Mean +/- standard deviation (SD) pachymetry and endothelial cell counts before and after instillation were 504.48 +/- 5.45 microm and 2325.76 +/- 192.52 cells/mm2 and 503.52 +/- 5.75 microm and 2297.60 +/- 192.08 cells/mm2, respectively, suggesting no significant difference in the above two parameters. Similarly, in the fellow control eyes, mean +/- SD pachymetry and endothelial cell counts before and after instillation were 502.80 +/- 4.34 microm and 2326.72 +/- 191.93 cells/mm2 and 504.64 +/- 5.19 microm and 2313.60 +/- 192.03 cells/mm2, respectively. CONCLUSIONS: Topical 0.04% MMC drops do not significantly affect the corneal endothelium. However, its judicious use and long-term follow-up are mandatory.     

The influence of central corneal thickness on response to topical prostaglandin analogue therapy

ObjectiveCentral corneal thickness (CCT) affects intraocular pressure (IOP) readings; however, CCT influence on topical medication efficacy is unknown. We evaluated the IOP-lowering effect of topical prostaglandin analogues (PGAs) in relation to CCT.DesignPost hoc analysis of a randomized prospective trial.MethodSubjects randomized to a PGA were followed for 24 weeks and were analyzed for relationship between CCT and IOP lowering.ParticipantsPatients with either newly diagnosed ocular hypertension or open-angle glaucoma.Results75 subjects were enrolled. The mean age was 62.7 ± 10.5 years; 48 were Caucasian. The mean CCT was 562.4 ± 41.4 μ. At repeated measures, ANCOVA analysis showed a significant effect of both baseline IOP (p < 0.0001) and CCT (p = 0.003) on IOP. At week 12, a regression analysis of the effect of CCT on baseline IOP showed that for every 10 μ increase in CCT there was 0.3 mm Hg less IOP decrease from baseline.ConclusionsWe found a statistically significantly association between a lower mean IOP and a thinner cornea when baseline IOP is controlled for. The magnitude of the relationship is small but may be clinically significant in patients with either very thin or very thick corneas.     

Effect of topical vitamin E on ethanol-induced corneal epithelial apoptosis

PURPOSE: Ethanol is used to loosen the corneal epithelium before photoablation in laser subepithelial keratomileusis (LASEK). In this study, the apoptotic index of corneal epithelium after ethanol exposure and the effects of topical vitamin E were evaluated. METHODS: The study was performed on 28 rabbit eyes in four groups. Group 1 comprised the controls. In group 2, 20% ethanol was applied topically for 20 seconds. In group 3, topical vitamin E was applied following 20% ethanol application. In group 4, only topical vitamin E was applied. Apoptosis was evaluated with TUNEL assay and transmission electron microscopy. RESULTS: Epithelial apoptosis was detected in all specimens in group 2. No apoptosis was detected in other groups except for one eye in group 1. The apoptotic index in group 2 was statistically higher than other groups (P < .001).     

贝伐单抗抑制角膜新生血管的实验研究

目的评价贝伐单抗（avastin）局部应用对小鼠角膜新生血管（CNV）的抑制作用。方法通过碱烧伤建立CNV模型,将30只Balb／c小鼠随机分成5组,A组贝伐单抗1mg／mL每日点眼2次;B组贝伐单抗3mg／mL每日点眼2次;C组贝伐单抗5mg／mL每日点眼2次;D组0．1％地塞米松每日点眼2次;E组生理盐水每日点眼2次。分别于术后3、7、14d观察CNV情况并拍照。术后第14天,处死全部小鼠,行CNV内皮细胞荧光标记,计算CNV所占全角膜面积的比例。结果各组CNV面积为A组（37．11±3．17）％、B组（29．75±3．56）％、C组（18．76±2．55）％、D组（20．91±2．75）％,E组（41．65±2．11）％。各组小鼠CNV面积依次为c组〈D组〈B组〈A组〈E组,C组同A、B、E组比较差异均有统计学意义（P〈0．01）,c组与D组比较差异无统计学意义（P=0．694）。结论局部应用贝伐单抗对小鼠角膜化学烧伤后的CNV有抑制作用。     

Effect of topical anti-inflammatory drugs on corneal and limbal wound healing

PURPOSE: To examine the effect of topical treatment with either steroidal or nonsteroidal anti-inflammatory drugs (NSAIDs) on the wound healing of corneal and limbal incisions using histologic criteria. SETTING: Loyola University Medical Center, Maywood, Illinois, USA. METHODS: Eighteen eyes of 9 cats were used for the study. All right eyes received a temporal limbal incision and the left eyes, a clear corneal incision. All eyes were treated with ofloxacin 0.3% postoperatively for 3 days. The animals were equally divided among 3 groups. Group 1 received topical steroid drops (prednisolone acetate 1%) for 7 days maximum; Group 2 received topical NSAID drops (ketorolac tromethamine 0.5%) for 7 days maximum; Group 3 received no additional treatment. One animal from each group was killed and the eye enucleated 3, 7, or 28 days postoperatively. The eyes were processed for staining with hematoxylin-eosin and smooth muscle actin, and corneal sections were evaluated in a blind fashion by an ophthalmic pathologist. RESULTS: Three and 7 days after surgery (1) the limbal incision exhibited more prominent wound healing than the similarly treated clear corneal incision, and (2) the steroid-treated corneas had less wound healing than untreated or NSAID-treated corneas. At 28 days, the wounds in all eyes were almost completely healed. CONCLUSIONS: Limbal incisions heal faster than clear corneal incisions. Steroids, but not NSAIDs, inhibit wound healing. Cataract surgery using limbal incisions and postoperative topical NSAIDs may result in faster wound healing and provide a reduced risk of related postoperative complications.     

Effect of topical steroids on corneal epithelial healing after vitreoretinal surgery

PURPOSE: Topical steroid use is usually avoided in cases of corneal epithelial defect. We evaluated the effect of topical steroid treatment on corneal epithelial healing after epithelial debridement in vitreoretinal surgery. METHODS: Our study population included 85 eyes undergoing vitreoretinal surgeries in our clinic. We prospectively compared the duration of corneal epithelial wound healing in 43 eyes in which topical dexamethasone was used with that in 42 eyes in which topical dexamethasone was not used in the early postoperative period after epithelial debridement. Factors that may retard corneal epithelial healing, including pre- and intraoperative topical solutions, median operative time, the presence of diabetes mellitus, prior ocular surgeries, pseudophakia, aphakia and the presence of intraocular gas or silicone oil in aphakic patients, were not significantly different between the two groups. RESULTS: The mean corneal epithelial defect closure time was 59.7 +/- 2.6 hours (mean +/- SEM) in the group receiving topical steroid treatment, and 61.9 +/- 2.6 hours in the group that did not receive steroids. CONCLUSION: Topical dexamethasone administered five times/day did not significantly retard corneal epithelial healing in subjects undergoing vitreoretinal surgery with postoperative topical steroid treatment, compared with subjects who did not receive steroid treatment.     

Effectiveness of 0.1% topical salicylic acid on blepharoconjunctivitis affecting glaucoma patients treated with topical prostaglandin analogues: a prospective randomized trial

AIM: To evaluate the efficacy of 0.1% topical salicylic acid (TSA) to treat iatrogenic chronic blepharoconjunctivitis in patients with primary open angle glaucoma (POAG), treated with topical prostaglandin analogues (TPAs). METHODS: Totally 60 patients were randomly distributed into 3 equal size groups, two of which treated with 0.1% TSA (OMKASA®) and 0.1% topical clobetasone butyrate (TCB; VISUCLOBEN®) respectively, and one consisting of untreated controls. The parameters taken into account at baseline (T0) and after 30d (T1) of therapy were: conjunctival hyperemia, lacrimal function tests [Schirmer I test and break up time (BUT)] and intraocular pressure (IOP). RESULTS: Conjunctival hyperemia showed a substantial improvement in both treated groups (P<0.001) but not among controls. Similarly, lacrimal function tests displayed an improvement of Schirmer I test in both treated groups (P<0.05) and an extension of BUT only in the group treated with 0.1% TSA (P<0.05). The IOP increase was statistically significant only in those patients treated with 0.1% TCB (P<0.001). CONCLUSION: The 0.1% TSA has proved to be an effective anti-inflammatory treatment of blepharoconjunctivitis affecting glaucoma patients on therapy with TPAs, leading to a sizeable decrease of inflammation as well as both quantitative and qualitative improvement of tear film. Furthermore, differently from 0.1% TCB, it does not induce any significant IOP increase.     

Experimental assessment of human corneal hysteresis

PURPOSE: Hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis using experimental means. METHODS: Twenty-nine human corneas with 50-95 year age were subjected to cycles of pressure loading and unloading. Two pressure application rates were adopted to approximate static and dynamic loading conditions. RESULTS: The behavior under both loading and unloading was found to stiffen with increased age. The unloading behavior appeared to be largely independent of the pressure level at which unloading started. The difference between the behavior patterns under loading and unloading was quantified and used as a measure of corneal hysteresis. The hysteresis area was significantly larger with faster loading and with decreased age. CONCLUSIONS: The trend for hysteresis to decrease with age is in agreement with previous clinical observations. Hysteresis was also found to increase with faster pressure application.     

角膜滞后量在青光眼中的作用

青光眼是全球首位不可逆致盲性眼病,其具体发病机制尚不清楚,但颇受重视的是眼压和房水流出通道等方面。近年,研究人员开始越来越多地关注非压力依赖因素如角膜滞后量(CH)在青光眼中的作用。CH是角膜的生物力学参数,它反映了角膜的黏性阻力,即吸收和分散能量的能力。CH在临床上很容易获得,可作为眼后部组织生物力学特性的替代标志物,如筛板和乳头周围巩膜,这些组织可能与青光眼损伤的易感性有关。有研究提供了CH与青光眼临床相关结果之间的联系的证据。本文综述了CH在青光眼中的作用的最新发现,从CH的测量方法、CH与中央角膜厚度、青光眼性视野进展、视盘损害、视网膜神经纤维层缺失等方面进行了归纳和总结。