Gene Kim

Corneal confocal microscopy is efficient, well-tolerated, and reproducible

In order to develop an efficient, reproducible, and well‐tolerated protocol for assessing corneal innervation, 11 normal subjects underwent corneal confocal microscopy (CCM) using a Heidelberg Retinal Tomography III microscope. Five standardized locations were sampled in the left eye and one centrally in the right. The protocol was repeated 1–4u2009weeks later. A blinded technician measured nerve fiber length (NFL) and tortuosity coefficient (TC). The relationship between image location and NFL and TC was assessed using one‐way analysis of variance, and reproducibility determined using relative intertrial variability and intraclass correlation coefficients. NFL reproducibility was maximized by averaging four or more images from the left eye, or one central image from both eyes. TC was less reproducible. CCM is a rapid, well‐tolerated, and reproducible method for assessing corneal innervation.

Assessing the Reproducibility of Quantitative In Vivo Confocal Microscopy of Corneal Nerves in Different Corneal Locations.

Purpose: To evaluate the reproducibility of in vivo confocal microscopy for quantitative corneal nerve analysis in different corneal locations. Methods: Corneal confocal microscopy was performed on 10 healthy participants, and the corneal nerve fiber length, corneal nerve fiber density, corneal nerve branch density, and tortuosity coefficient were measured at 5 predetermined locations for only the right eye. Bland–Altman plots, intraclass correlation coefficient (ICC), and coefficient of variation of all 4 corneal nerve measurements were compared between 2 visits and between readers to assess reproducibility. Two technicians performed a masked analysis of images from both visits. Results: Ten participants with a mean age of 31.3 ± 2.8 years were imaged at 2 different time points separated by a mean of 4.3 ± 4.3 weeks. The interobserver agreements were better than the intervisit agreements for all the 4 corneal nerve measurements as evaluated using Bland–Altman plots. The intervisit ICC ranged from 0.13 to 0.45, and the interobserver ICC ranged from 0.55 to 0.94. The differences between observers and the differences between sessions were not statistically different among all the 5 locations (P > 0.1) for each corneal nerve measurement. Conclusions: Single confocal images have poor reliability for any of the 4 corneal nerve measurements, and there is no single location on the cornea that has improved reproducibility. Averaging 5 images, from different locations, improves the reproducibility and is essential for obtaining clinically meaningful data.

Comparison of the ratio of keratometric change to refractive change induced by myopic ablation.

PURPOSEnTo compare the ratio of keratometric change (ΔK) to refractive change (ΔSE) induced by refractive laser ablation.nnnMETHODSnThe charts of 3337 eyes that underwent LASIK or photorefractive keratectomy (PRK) from 2002 to 2011 were retrospectively reviewed, and the ratio ΔK/ΔSE measured at 3 months postoperatively was compared between eyes with low ΔSE (0.00 to 2.99 diopters [D]), moderate ΔSE (3.00 to 5.99 D), and high ΔSE (6.00 to 8.99 D). Eyes were further stratified by LASIK vs PRK; custom vs conventional treatments; microkeratome vs IntraLase (Abbott Medical Optics Inc) femtosecond laser-created flaps; and flat (38.00 to 41.99 D) vs moderate (42.00 to 45.99 D) vs steep (46.00 to 49.99 D) preoperative keratometry, and the ratio ΔK/ΔSE was similarly compared.nnnRESULTSnSignificant differences were found in the ratio ΔK/ΔSE among eyes with low ΔSE (1.00±0.50 D), moderate ΔSE (0.83±0.19 D), and steep ΔSE (0.80±0.15 D) (P<.001), and between eyes with moderate and high ΔSE in LASIK vs PRK, custom vs conventional treatments, and microkeratome vs IntraLase flaps. Significant differences in the ratio ΔK/ΔSE were also found in eyes with low, moderate, and high ΔSE regardless of preoperative keratometry. The ratio ΔK/ΔSE compared with ΔSE follows a nonlinear pattern and tended to be higher and more variable at lower amounts of correction.nnnCONCLUSIONSnThe change in simulated keratometry required to achieve 1.00 D of myopic refractive correction decreased as the amount of refractive change increased, was more variable with lower amounts of correction, and followed a nonlinear relationship. Many variables, such as LASIK vs PRK, custom vs conventional, and microkeratome vs IntraLase flaps, affected the ratio of ΔK/ΔSE for moderate and high myopic corrections.

Change in keratometry after myopic laser in situ keratomileusis and photorefractive keratectomy

Purpose To compare the change in keratometry (K), spherical equivalent (SE), and visual acuity after myopic laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK). Setting Academic tertiary care center. Design Retrospective review. Methods The postoperative K, SE, and uncorrected and corrected distance visual acuities were measured 6 months, 9 months, 1 year, 2 years, 3 years, 4 to 5 years, 6 to 7 years, and 8+ years postoperatively. A difference (&Dgr;) for each variable was calculated from its 6‐month postoperative baseline. The rates of change were grouped based on the magnitude of myopic correction (0.00 to 2.99 diopters [D]; 3.00 to 5.99 D; 6.00 to 8.99 D), type of surgery (LASIK versus PRK), and age (<34 years; 34 to 45 years; >45 years). Results Statistically significant differences were found in the rates of change between low and moderate corrections to high corrections for &Dgr;Kavg (P = .0472 and P = .0091, respectively) and &Dgr;SE (both P < .0001). Statistically significant differences were found in the rate of change in &Dgr;Kavg between all 3 ages groups (P = .0330, P = .0051, and P <.0001) and in &Dgr;SE between ages less than 34 years and 34 to 45 years to ages over 45 years (P = .0158 and P = .0015, respectively). There was no significant difference in the rate of change in &Dgr;Kavg and &Dgr;SE between LASIK and PRK (P = .3599 and P = .9403, respectively). Conclusion There was keratometric and refractive regression for myopic LASIK, with the rate of regression depending on treatment magnitude and age. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Amnion doughnut: a novel method for sutureless fixation of amniotic membrane to the bulbar and palpebral conjunctiva in acute ocular-involving Stevens-Johnson syndrome.

Purpose: The aim of this study was to describe a novel surgical method for the sutureless placement of amniotic membrane on the bulbar and palpebral conjunctiva in the setting of ocular-involving acute Stevens–Johnson syndrome. Methods: Within 6 days of an acute Stevens-Johnson episode, a 27-year-old male developed early symblepharon, despite aggressive lubrication and topical steroid therapy. He underwent symblepharon lysis and placement of an amniotic membrane wrapped around a symblepharon ring. Results: The patient maintained 20/20 vision in each eye with no recurrent symblepharon formation except for the temporal canthus (which was not covered with amniotic membrane). Conclusions: Symblepharon rings covered in amniotic membrane provide a sutureless way to fixate amniotic membrane to the bulbar and palpebral conjunctiva. This gave very good anatomic and functional outcomes in a patient with acute Stevens–Johnson syndrome. Future research could be directed toward the development of a symblepharon ring that will be able to better protect the far temporal conjunctiva.

Re: “Topical Tetracaine Used for 24 Hours Is Safe and Rated Highly Effective by Patients for the Treatment of Pain Caused by Corneal Abrasions: A Double‐blind, Randomized Clinical Trial”

We have read the recent study “Topical tetracaine used for 24 hours is safe and rated highly effective by patients for the treatment of pain caused by corneal abrasions: a double-blind, randomized clinical trial” by Waldman et al. with great concern. While tetracaine temporarily anesthetizes pain, its routine usage to treat traumatic corneal abrasions in an emergency department is dangerous and can lead to blinding ocular complications. In this study, there was no statistically significant difference in the recalled pain between the tetracaine drops and placebo. Also, patients found to have alternate diagnoses on follow-up were excluded from analysis. After reanalyzing the data to include these patients, the rate of infiltrate in the tetracaine group is actually 1 in 46, or 2.2%. According to Upadhyay et al., the incidence of corneal ulcers in the setting of traumatic corneal abrasion among patients presenting within 24 hours with antibiotic prophylaxis was 1 in 393 or 0.26%—or an entire order of magnitude less than the tetracaine group in this study. Given the entire log unit of increased risk of infection with minimal benefit in regards to pain, it seems unwise to recommend a drop that is only likely to harm the eye. The methodology used to diagnose corneal abrasions is ambiguous. None of the corneal evaluations were performed by an ophthalmologist, and some of the evaluations were not even done by a physician. “Fluorescein uptake” is a very general term and includes etiologies from simple corneal abrasion to small corneal perforation and open globe. This study only noted the presence or absence of staining. There is no quantification of the size of epithelial defect, type and pattern of staining, and no slit-lamp examination, which could have found the subtle differences in ocular surface toxicity between the tetracaine and placebo groups. Along this line, prescription of tetracaine for more serious pathologies occurred in six of 122 patients (roughly 5%). Extrapolating the author’s data, this particular center is, on average, sending out 14 to 15 misdiagnosed large corneal lacerations per year, roughly five of which develop infiltrates and scars. Tetracaine’s possible contribution to a delay in diagnosis of these more serious pathologies is concerning. The abuse and addiction potential for topical anesthetics in this situation is also high. Many patients who develop topical anesthetic abuse start by using topical anesthetic for a 24-hour period. At one institution, one in eight (12.5%) anesthetic abuse cases started from a posttraumatic corneal abrasion; 11 of 12 eyes that had anesthetic abuse developed infiltrates or scars in an average time of 15 days. The complications of anesthetic abuse can cause significant visual morbidities, including corneal infections, ulcerations, and perforations, which can require major surgical intervention and occasionally removal of the eye. Given the minimal benefit in pain, and the serious consequences of prolonged tetracaine use, we would provide strong caution in using topical anesthetics for traumatic corneal abrasions. We would recommend the usage of antibiotic ointments, which have a better safety profile and still provide some comfort. doi: 10.1111/acem.12470

Complications related to the explantation of cosmetic iris implants

The number of times an OVD was injected is also a valuable question that reflects the experience and mastery of the surgeon. As Smith et al. mentioned in the article, if the cystotome tip was on the OVD syringe, the OVD could easily be instilled or reinstilled without removing the tip. Considering that many surgeons in the world would use a cystotome separately, this step of the study could be reevaluated using a cystotomewithout anOVD syringe. Another possibility is to include or exclude this question in the evaluation tool in accordance with the type of syringe that is attached to the cystotome. Although it is not possible to evaluate verbal intervention of the attending surgeon by raters on video records, after validating a standard tool, it may be possible to add whether there was verbal intervention and the level of verbal intervention by the attending surgeon as another question in the scale. As Smith et al. mentioned, to establish a basis for evaluating videos independently, exemplifying specific grades for each question would be efficacious and it would also be possible for surgeons to share their records with the authors or other surgeons investigating this method.

Accuracy of Computed Tomography Imaging Criteria in the Diagnosis of Adult Open Globe Injuries by Neuroradiology and Ophthalmology

OBJECTIVEnThe objective was to evaluate the sensitivity and specificity of computed tomography (CT) diagnosis of open globes, determine which imaging factors are most predictive of open globe injuries, and evaluate the agreement between neuroradiologist and ophthalmologist readers for diagnosis of open and closed globes.nnnMETHODSnThis study was a retrospective cohort study. Patients who presented to Memorial Hermann-Texas Medical Center with suspicion for open globes were reviewed. One neuroradiologist and two ophthalmologists masked to clinical information reviewed CT images for signs concerning for open globe including change in globe contour, anterior chamber deformation, intraocular air, vitreous hemorrhage, subretinal fluid indicating retinal or choroidal detachment, dislocated or absent lens, intraocular foreign body, and orbital fracture. Using the clinically or surgically confirmed globe status as the true globe status, sensitivity, specificity, and agreement (kappa) were calculated and used to investigate which imaging factors are most predictive of open globe injuries.nnnRESULTSnA total of 114 patients were included: 35 patients with open globes and 79 patients with closed globes. Specificity was greater than 97% for each reader, and sensitivity ranged from 51% to 77% among readers. The imaging characteristics most consistently used to predict an open globe injury were change in globe contour and vitreous hemorrhage (sensitivityxa0= 43% to 57%, specificityxa0>xa098%). The agreement of impression of open globe between the neuroradiologist and ophthalmologists was good and excellent between ophthalmologists.nnnCONCLUSIONSnComputed tomography imaging is not absolute, and the sensitivity is still inadequate to be fully relied upon. The CT imaging findings most predictive of an open globe injury were change in globe contour and vitreous hemorrhage. Clinical examination or surgical exploration remains the most important component in evaluating for a suspected open globe, with CT imaging as an adjunct.