The accuracy of Goldmann applanation tonometry over silicone hydrogel contact lenses in patients with glaucoma

PurposeTo investigate the accuracy of measuring intraocular pressure over a silicone hydrogel contact lens using Goldmann applanation tonometry in eyes with glaucoma.MethodsThis was a prospective, randomized study and enrolled 28 patients (28 right eyes) with primary open angle glaucoma. Intraocular pressure was taken with and without a silicone hydrogel contact lens (−0.50 D), in situ (using Goldmann applanation tonometry), in a randomized order of measurements. Statistical analysis was performed using paired t-test and Bland–Altman plot.ResultsThe mean difference (± standard deviation) found between intraocular pressure measurement without (mean 16.7 ± 3.2 mmHg) and with (mean 17.3 ± 3.0 mmHg) contact lens was found to be −0.57 ± 2.3 mmHg (95% confidence interval, −1.5 to 0.3). No significant statistical difference was found between the two groups with paired t-test (p = 0.19). The Bland Altman plot showed some evidence of increasing variability of differences between two measures of intraocular pressure, with increasing intraocular pressure. The 95% limits of agreement of the Bland Altman plot were unacceptably large (−5 mmHg to 3.9 mmHg).ConclusionAgreement between Goldmann applanation tonometry with and without contact lenses seems to be poor in patients with glaucoma, especially for high intraocular pressure.     

Changes in Retinal N-Acylethanolamines and their Oxylipin Derivatives During the Development of Visual Impairment in a Mouse Model for Glaucoma

Neurons are especially susceptible to oxidative damage, which is increasingly implicated in neurodegenerative disease. Certain N‐acylethanolamines (NAEs) have been shown to protect neurons from oxidative stress. Since glaucoma may be considered a neurodegenerative disorder and the survival of retinal neurons could also be influenced by N‐acylethanolamines, our goal was to quantify changes in certain N‐acylethanolamine species and their oxylipin derivatives in the retina of a mouse model for glaucoma. We also sought to identify relationships between these and parameters of glaucoma disease development, specifically intraocular pressure, visual acuity, and contrast sensitivity. Five N‐acylethanolamine species and three NAE oxylipin derivatives were quantified in retina from young and aged DBA/2Crl mice. N‐Acylethanolamines and NAE‐oxylipins in retinal extracts were quantified against deuterated standards by isotope dilution gas chromatography–mass spectrometry. Levels (nmol/g dry weight) of N‐arachidonoylethanolamine (anandamide; NAE 20:4) were significantly (p = 0.008) decreased in aged (2.875 ± 0.6702) compared to young animals (5.175 ± 0.971). Conversely, the anandamide oxylipin, 15(S)‐HETE ethanolamide (15(S)‐HETE EA), was significantly (p = 0.042) increased in aged (0.063 ± 0.009) compared to young animals (0.039 ± 0.011). Enzymatic depletion of the anandamide pool by 15‐lipoxygenase and consequent accumulation of 15(S)‐HETE ethanolamine may contribute to decreased visual function in glaucomatous mice. Since N‐acylethanolamines effectively attenuate glaucoma pathogenesis and associated visual impairment, our data provides additional rationale and novel targets for glaucoma therapies.     

Comparative amperometry on ocular-surgery electrolytes in eye-splinter trauma from galvanized-steel electrochemistry

Metal foreign bodies in the eye are commonly removed utilizing a surgical approach through the vitreous cavity, which requires a maintained ocular pressure by infusion of replacement “irrigation solution”, i.e., electrolyte. However, when in contact with aerated electrolyte, if the fragment comprises galvanized steel, the component metals can act as a bimetallic zinc/steel cell, thereby electrochemically generating injurious amounts of hydroxyl ion OH⁻. The effect on this electrochemical reaction of the compositions of the irrigation solutions in use, and of their analogues, has thus been investigated, to seek the least damaging. The inter-metallic current relates directly to the rate of the injurious reaction, hence amperometry has been the principal probe employed in our study. Establishing reproducible conditions of contact between electrolyte and the steel–zinc combination forms a major focus of the study, which is to attain amperometric reproducibility in the comparison of the electrolytes. Geometry-sensitive directed injection of test solution into a cell with pre-fixed separate steel and Zn electrodes achieved the desiderata. Besides potentiometry and amperometry, pH and buffering by the various test solutions, and the effects of surfactants, were also examined. Free-radical intermediates in the oxygen processes are further injurious suspects. Anaerobic conditions that would preclude both intermediates and OH⁻ are unfortunately damaging to the structures of the eye, so alternative surgical procedures are needed. Anti-corrosion aspects are considered.

Long-term changes in straylight induced by corneal refractive therapy: A pilot study

PurposeTo assess long-term intraocular straylight changes induced by corneal refractive therapy (CRT) and to determine whether these changes persist after cessation of CRT lens wear.MethodsA single-center, prospective, longitudinal study was performed in 22 subjects (group 1) undergoing overnight corneal refractive therapy for 1 year. Ten right eyes of 10 subjects (group 2) with emmetropia served as controls. In each subject, high contrast visual acuity (HCVA), manifest refraction and intraocular straylight were determined at several time points during treatment and 1 month after discontinuing treatment. Straylight was measured using the van den Berg straylight meter (third generation). EDTRS charts (logMAR units) were used to assess HCVA. For both groups, only data for the right eyes were analyzed.ResultsStraylight (mean ± standard deviation) significantly fell from baseline (0.98 ± 0.13) to values recorded after 1 month (0.88 ± 0.13, p = 0.011), 3 months (0.88 ± 0.13, p = 0.004), 6 months (0.88 ± 0.13, p = 0.000) and 12 months (0.76 ± 0.12, p = 0.003) of treatment. One month after discontinuing CRT lens wear, straylight was still significantly lower than baseline (0.89 ± 0.13, p = 0.003). No correlations were observed between intraocular straylight and HCVA.ConclusionsGood refractive outcomes and reductions in straylight were observed in response to corneal refractive therapy for myopia. The reduction in straylight observed after discontinuing CRT warrents further investigation.     

Applanation tonometry in silicone hydrogel contact lens wearers

INTRODUCTION: Previous studies have investigated intraocular pressure (IOP) measurements through conventional soft (hydrogel) therapeutic contact lenses, and have found that an accurate IOP can be recorded in normal eyes, and in eyes with abnormal anterior segments. The IOP measurement through soft contact lenses may be affected by the water content and centre thickness of the lens. Silicone hydrogel contact lenses are now being used as therapeutic contact lenses due to their high oxygen permeability. The purpose of this study is to investigate if IOP can be accurately measured in a subject wearing a silicone hydrogel contact lens. METHODS: In a cohort study, the IOP was measured with a Goldmann applanation tonometer without a contact lens and then repeated with a hydrogel contact lens in situ. RESULTS: The IOP of 20 eyes of 10 volunteers with no ocular pathology was measured. The mean difference (+/-S.D.) found between IOP measurement with (mean 15.55+/-1.70 mmHg) and without (mean 16.05+/-1.90 mmHg) contact lens was found to be -0.5+/-0.89 mmHg. Statistical analysis was performed which revealed a correlation coefficient of 0.89. No significant statistical difference was found between the two groups with paired t-test (p=0.19). CONCLUSION: Accurate measurement of IOP by applanation tonometry can be achieved through a silicone hydrogel contact lens.     

Visual performance and patient satisfaction of multifocal contact lenses in eyes undergoing monofocal intraocular Lens implantation

PurposeTo assess visual performance and patient satisfaction of multifocal contact lenses in eyes having monofocal intraocular lens (IOL) implantation.MethodsWe prospectively assessed uncorrected visual acuity at all distances (0.3, 0.4, 0.5, 0.7, 1, and 5 m), higher-order aberrations (HOAs), objective scattering index (OSI), contrast sensitivity, and patient satisfaction, before and during multifocal contact lenses wear in IOL-implanted eyes.ResultsVisual acuity at 0.3, 0.4, 0.5, 0.7, 1, and 5 m during wearing multifocal contact lenses was 0.21 ± 0.08, 0.11 ± 0.06, 0.01 ± 0.08, -0.02 ± 0.10, -0.02 ± 0.08, and -0.01 ± 0.07, respectively. We found a significant improvement at near to intermediate distances (30, 40, and 50 cm), but no significant change at intermediate to far distances (70 cm, 1 m, and 5 m). Log contrast sensitivity significantly decreased at 6 and 12 cycles/degrees, but did not significantly change at 1.5, 3, and 18 cycles/degrees. Third-order aberrations significantly increased after CL treatment, but fourth-order aberrations or total higher-order aberrations did not significantly change during CL treatment. The OSI and log(s) did not significantly change during CL treatment. The patient satisfaction score for overall vision significantly improved during CL treatment.ConclusionsMultifocal contact lenses significantly improved visual acuity at near to intermediate distances, and subsequent patient satisfaction, even though contrast sensitivity function slightly decreased, suggesting its viability of presbyopic correction in monofocal IOL-implanted eyes.     

白内障超声乳化术后前囊环与人工晶状体位置的变化

目的观察超声乳化白内障术后前囊环大小、形态与折叠式人工晶体匹配的情况以及对后者位置的影响,探讨前囊环与人工晶体最佳匹配的方式。方法散大瞳孔,在裂隙灯显微镜下观察到122例(132只眼)年龄相关性白内障患者做5.0～5.5mm直径中央连续环形撕囊术后行超声乳化伴折叠式人工晶体植入3个月后晶状体囊结构、前囊环与囊袋内人工晶体位置的变化。结果全部术眼整个晶状体囊袋塌陷、缩小,前囊环呈灰白色环状(Soemmering环),前囊环将人工晶状体光学面完全包埋,无夹持(67眼);不完全包埋,部分夹持(43眼);没有包埋,完全夹持(22眼)3种状态。其中完全夹持眼组后囊膜中央区混浊发生率(50.0%)明显高于部分夹持眼组(18.6%)和无夹持眼组(8.96%),差异均有显著性意义(P<0.05);无夹持眼组人工晶体正位率(94.0%)与部分夹持眼组人工晶体正位率(41.9%)、完全夹持组人工晶体正位率(77.3%)差异均有非常显著性意义(P<0.05)。结论超声乳化白内障吸除折叠式人工晶体植入术后晶状体囊结构发生一系列的变化,其中前囊环将人工晶状体光学面完全包埋的匹配方式是维持晶体后囊膜透明和人工晶体居中的最佳位置的方式。     

Evaluation of central corneal thickness after cataract surgery,penetrating keratoplasty and long-term soft contact lens wear

PurposeThe aim of this study was to compare central corneal thickness (CCT) between corneas of normal healthy eyes (cNHE), corneas of eyes that had undergone cataract surgery by clear corneal phacoemulsification with implantation of an intracapsular intraocular lens (cIOL), corneal grafts after penetrating keratoplasty (gPK) and corneas of long-term soft contact lens wearers (cCL).MethodsThe study design was a consecutive cross-sectional trial. CCT was measured using rotating Scheimpflug camera (Pentacam, software version 1.16r04) in 80 cNHE, 79 cIOL, 46 gPK and 78 cCL. Analysis of variance (one-way ANOVA) was performed to compare differences of mean values between these four groups. Pearson's or Spearman's correlation coefficient (r) was determined between CCT value and age, follow up time after penetrating keratoplasty (timePK) or contact lens wearing time (timeCL).ResultsMeans of CCT measurements were comparable between cNHE (mean CCT ± standard deviation, 554 ± 36 μm), cIOL (551 ± 40 μm) and gPK (534 ± 52 μm) as determined by one-way ANOVA. Mean CCT values in cCL (537 ± 37 μm) were statistically significantly lower in comparison to cNHE (p = 0.026, 95% CI = 1.43–31.44). There was no linear correlation between age and CCT values of cNHE and cIOL (p = 0.841, r = −0.031 and p = 0.931, r = 0.011, respectively). No linear relationship was determined between CCT values of cCL and timeCL (p = 0.315, r = −0.125). CCT values of gPK did not correlate with timePK (p = 0.738, r = 0.054).ConclusionsThe data reported here indicate that in the same statistical model among CCT values of cNHE, cIOL and gPK only long-term soft contact lenses (CL) wearer have significantly lower CCT measurements.