Yaniv Barkana

Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low-coherence reflectometry pachymeter, and ultrasound pachymetry

PURPOSE: To assess the intraoperator repeatability and interoperator reproducibility of central corneal thickness measurements by the Pentacam Scheimpflug imaging system (Oculus) and the optical low‐coherence reflectometer (OLCR) pachymeter (Haag‐Streit) and to compare them with those of ultrasound (US) pachymetry. SETTING: Assaf Harofe Medical Center Ophthalmology Outpatient Clinic, Zerifin, Israel. METHODS: Repeatability was determined from 10 successive measurements in each of 4 healthy patients. Reproducibility for the Pentacam Scheimpflug system was determined from measurements by 2 operators in each of 24 patients; in these 24 patients, central corneal thickness measurements were compared between the Pentacam and US pachymetry. For the OLCR pachymeter, reproducibility was determined from measurements by 2 operators in each of 16 patients, in whom central corneal thickness was also measured with the Pentacam. RESULTS: Mean coefficient of repeatability was 0.84% for the Pentacam Scheimpflug system and 0.33% for the OLCR pachymeter. For the Pentacam, the coefficient of interoperator reproducibility was 1.10% and the 95% limits of agreement were −10.2 μm to +11.9 μm. Mean difference between Pentacam and US was 6.09 μm. For the OLCR pachymeter, the coefficient of interoperator reproducibility was 0.59% and the 95% limits of agreement were −5.4 μm to +7.0 μm. Mean difference between central corneal thickness values obtained with the OLCR pachymeter and Pentacam Scheimpflug system was 1.7 μm. CONCLUSIONS: Objective, noncontact measurement of central corneal thickness with the Pentacam Scheimpflug system and OLCR pachymeter was convenient and yielded excellent intraoperator repeatability and interoperator reproducibility. Central corneal thickness values obtained with the Pentacam were similar to those obtained with both the OLCR pachymeter and an US pachymeter. Further research is needed to corroborate whether central corneal thickness measurements by the Pentacam and OLCR devices can be used interchangeably and are more clinically useful than US pachymetry.

Laser Eye Injuries

Laser instruments are used in many spheres of human activity, including medicine, industry, laboratory research, entertainment, and, notably, the military. This widespread use of lasers has resulted in many accidental injuries. Injuries are almost always retinal, because of the concentration of visible and near-infrared radiation on the retina. The retina is therefore the body tissue most vulnerable to laser radiation. The nature and severity of this type of retinal injury is determined by multiple laser-related and eye-related factors, the most important being the duration and amount of energy delivered and the retinal location of the lesion. The clinical course of significant retinal laser injuries is characterized by sudden loss of vision, often followed by marked improvement over a few weeks, and occasionally severe late complications. Medical and surgical treatment is limited. Laser devices hazardous to the human eye are currently in widespread use by armed forces. Furthermore, lasers may be employed specifically for visual incapacitation on future battlefields. Adherence to safety practices effectively prevents accidental laser-induced ocular injuries. However, there is no practical way to prevent injuries that are maliciously inflicted, as expected from laser weapons.

Effect of diabetes mellitus on biomechanical parameters of the cornea.

PURPOSE: To compare parameters of biomechanical response of the human cornea measured as corneal hysteresis (CH) and corneal resistance factor (CRF) in patients with diabetes mellitus and healthy control subjects. SETTING: Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin, Israel. METHODS: In the right eye of each participant, the CH, CRF, Goldmann‐correlated intraocular pressure (IOPg), and corneal‐compensated intraocular pressure (IOPcc) were measured with the Ocular Response Analyzer. Central corneal thickness (CCT) was measured by ultrasonic pachymetry and intraocular pressure by Goldmann applanation tonometry (IOP GAT). Findings were compared between the 2 groups (control and diabetic). RESULTS: Forty diabetic patients (17 women, 23 men) and 40 healthy subjects (19 women, 21 men) were prospectively recruited. The mean CH was 9.3 mm Hg ± 1.4 (SD) and 10.7 ± 1.6 mm Hg and the mean CRF was 9.6 ± 1.6 mm Hg and 10.9 ± 1.7 mm Hg in the control group and diabetic group, respectively (both P < .0001). Diabetic corneas were significantly thicker (P = .019); the mean CCT was 530.3 ± 35.9 μm in the control group and 548.7 ± 33.0 μm in the diabetic group. The CH and CRF remained significantly different in multivariate analysis that included CCT. There was no statistically significant difference between the 2 groups in IOPcc, IOPg, or IOP GAT measurements. CONCLUSIONS: Diabetes mellitus affected biomechanical parameters of the human corneas, including increased CH, CRF, and CCT. Whether this observation has implications in the clinical management and understanding of corneal ectasia and glaucoma requires further study.

Endoscopic photocoagulation of the ciliary body after repeated failure of trans-scleral diode-laser cyclophotocoagulation

PURPOSEnTo report the successful control of intraocular pressure with endoscopic cyclophotocoagulation after repeated failure of trans-scleral diode-laser cyclophotocoagulation.nnnDESIGNnInterventional case report.nnnMETHODSnA 3 1/2-year-old child had intraocular pressure around 30 mm Hg in one eye despite full medical treatment and three procedures of trans-scleral diode laser photocoagulation.nnnRESULTSnEndoscopic view of the ciliary body revealed many misplaced laser burns in the pars plana region. Using direct endoscopic visualization of the ciliary body, precise, confluent burns were applied to the ciliary body. Six months after the procedure, intraocular pressure has remained under 20 mm Hg.nnnCONCLUSIONnEndoscopic cyclophotocoagulation can effectively lower intraocular pressure after recurrent external diode-laser photocoagulation has failed to do so. The direct visualization during the endoscopic procedure is particularly advantageous in cases with atypical ciliary body morphology, such as in pediatric glaucoma.

Neuroprotection in ophthalmology: a review

Evidence has accumulated that damaged neural cells may not inevitably degenerate, and that in vivo cells which are not directly injured by an insult may be adversely affected by adjacent dying cells. Neuroprotection is a strategy which aims to maximize recovery of injured neural cells and minimize secondary damage to neighboring cells. In this work, we review the current knowledge from neuroprotection research using in vitro and animal models of eye diseases, and clinical data.

Ocular parameters as an objective tool for the assessment of truck drivers fatigue

Ocular parameters are influenced by sleep derivation and the use of chemical substances which are two major causes for traffic accidents. We assessed the use of these parameters as an objective screening tool for a drivers fitness for duty. Pupillary diameter, pupil reaction to light and saccadic velocity were measured in 29 army truck drivers every morning for two months and compared to baseline measurements taken while the subjects were alert. An index which expressed the difference between study and baseline measurements was calculated, and drivers with significant deviation from baseline were disqualified and interviewed. Non-disqualified drivers served as controls. Twenty-nine percent of disqualified drivers reported sleeping less than the minimum of 7h required by army regulations compared with 8% of control drivers (p=0.01). Disqualified drivers had worse sleep quality the night before the test (Groningen Sleep Quality Scale, p=0.03) and incurred more accidents per driving day during their service (0.023 vs. 0.015 accidents/day, p=0.03). Two disqualified drivers admitted to using alcohol or sleeping pills. Thus, these ocular parameters may serve as a screening tool for drivers that are at high risk for driving. Drivers who were disqualified even once, tend to be involved in more motor vehicle accidents than their peers.

Prediction of visual outcome after penetrating keratoplasty for pseudophakic corneal edema

OBJECTIVEnTo evaluate the ability to predict visual outcome after penetrating keratoplasty (PKP) in patients with pseudophakic corneal edema (PCE) or aphakic corneal edema (ACE) based on preoperative parameters available from the patient history and ocular examination.nnnDESIGNnRetrospective noncomparative case series.nnnPARTICIPANTSnForty-eight patients who underwent 59 PKP procedures for PCE between 1997 and 2000 by two cornea specialists.nnnMETHODSnMedical records were retrospectively analyzed for variables in the history and ocular examination before PKP and visual outcome after PKP. Variables included age, gender, presence of diabetes or cardiovascular disease, method of intraocular lens (IOL) implantation during cataract surgery, vitreous loss during cataract surgery, time between cataract and PKP surgery, and maximal visual acuity reached after cataract surgery. The predictive value of each preoperative variable on post-PKP visual outcome was assessed using both univariate and multiple regression analyses.nnnMAIN OUTCOME MEASURESnStatistical significance for the predictive value of each preoperative variable on post-PKP visual outcome.nnnRESULTSnBest-corrected visual acuity (BCVA) of 20/40 or better was achieved in 13 patients (27%). The strongest predictor of this outcome was implantation of a bag-fixated or sulcus-fixated IOL at the time of cataract surgery (P = 0.007; odds ratio, 15.8; 95% confidence interval, 1.2-208). Less significant variables included BCVA after cataract surgery, time between cataract surgery and PKP, and gender.nnnCONCLUSIONSnIn planning and advising patients with pseudophakic or aphakic corneal edema who are candidates for PKP, the method of IOL implantation during the cataract surgery is the single most significant predictor of visual acuity after corneal transplantation. Bag-fixated or sulcus-fixated posterior chamber IOL was associated with a better visual outcome than anterior chamber IOL, scleral-fixated posterior chamber IOL, or aphakia.

Selective laser trabeculoplasty for primary angle closure with persistently elevated intraocular pressure after iridotomy.

PurposeTo determine whether selective laser trabeculoplasty (SLT) can lower intraocular pressure (IOP) in eyes with chronic primary angle closure, elevated IOP, and a patent iridotomy. Patients and MethodsPatients with chronic angle closure who had underwent iridotomy, had an IOP greater than 21u2009mm Hg and a gonioscopically visible pigmented trabecular meshwork for at least 90 degrees were enrolled. SLT was applied to open angle segments. Duration of follow-up was 6 months. ResultsSixty eyes of 60 patients were enrolled. The mean baseline IOP was 24.6±2.5u2009mm Hg. At 6 months, IOP reduction of ≥3u2009mm Hg or 4u2009mm Hg was measured in 82% and 72% of eyes, respectively, and IOP reduction of ≥20% or 30% was measured in 54% and 24% of eyes, respectively. When only eyes that were treated with the same number or fewer medications were considered, these IOP reductions were measured in 67%, 58%, 43%, and 15%, respectively. During the study period 1 eye (1.7%) required trabeculectomy owing to IOP elevation shortly after the SLT. There were no other significant complications attributable to SLT. ConclusionsSLT seems to be a safe and effective method of reducing IOP in many eyes with primary angle closure and a patent iridotomy in which there is a sufficient extent of visible trabecular meshwork.

Correlation between asthenopic symptoms and different measurements of convergence and reading comprehension and saccadic fixation eye movements.

PURPOSEnThe aim of this study was to evaluate the relationship between asthenopic symptoms, convergence amplitude, reading comprehension, and saccadic eye movements in children 8 to 10 years of age.nnnMETHODSnSixty-six children age 8 to 10 years were examined. Convergence was evaluated using (1) nonaccommodative target at near and distance, (2) a near computerized stereogram, and (3) measurement of the near point of convergence (NPC). Reading ability was examined by (1) a reading comprehension test in which children had to answer questions regarding a paragraph they read and (2) the Developmental Eye Movement Test (DEM), which evaluates saccadic speed and accuracy. Asthenopic symptoms were scored by an Asthenopic Symptoms Questionnaire.nnnRESULTSnAsthenopic symptoms score was correlated with the near point of convergence (r = -0.4; P = 0.003), convergence on a near stereogram (r = 0.38; P = 0.01) and distant light (r = 0.27; P = 0.04), but not with convergence on a near nonaccommodative target (r = 0.07; P = 0.6). The DEM ratio score was correlated with the asthenopic symptoms score (r = -0.32; P = 0.01), but the reading comprehension test score was not (r = 0.12; P = 0.4). There was correlation, however, between the time for completion of the reading comprehension test and the asthenopic symptoms score (r = 0.39; P = 0.006).nnnCONCLUSIONnAsthenopic symptoms score was correlated with convergence amplitude as measured, whereas accommodation is controlled and the ratio score calculated based upon DEM results. Further study is needed to evaluate the usefulness of the integration between symptom survey and objective reading examinations as screening tool for the diagnosis of convergence insufficiency.

Balloon catheter dilatation versus probing as primary treatment for congenital dacryostenosis.

Aim To compare the success rate of balloon catheter dilatation of the nasolacrimal duct with probing and irrigation as primary treatment for congenital dacryostenosis. Methods Charts of all children who were operated on for the first time for congenital dacryostenosis during the years 2004 to 2006 were analysed and the outcomes compared. Surgical success was defined as absence of epiphora and mucous discharge, and of increased tear lake, at the last visit. Results 68 children (114 eyes) underwent balloon catheter dilatation and 37 children (60 eyes) had probing. Children who had balloon dilatation were significantly older: mean age 55.98±113.6 (range 9.0–728.0)u2005months as opposed to 18.5±6.5 (range 7.0–60.0)u2005months, p<0.01). After a mean follow-up time of 15.4 (range 4–32)u2005months, 102 of 114 eyes were defined as successfully treated following balloon catheter dilatation (89.5% success rate) compared with 52 of 60 eyes following probing (86.7% success rate, p=0.581). Five of six patients (80%) in which the #00 probe could only hardly be inserted into the nasolacrimal duct because of firm bone resistance failed in the probing group, as opposed to only 2/10 (20%) in the balloon catheter group (p=0.03). Conclusion Children who had balloon catheter dilatation had a slightly better success rate than those who had probing; however, this difference was statistically significant only for patients who had a relatively narrow nasolacrimal bone duct.