Global metrics on ocular biometry: representative averages and standard deviations across ten countries from four continents.

BACKGROUND/OBJECTIVES: We provide global averages and standard deviations for ocular biometry-axial length (AL), corneal radius of curvature (CR), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), and central corneal thickness (CT). We hope a better understanding of normal and abnormal values will help clinicians gain further insight into their surgical outcomes, especially for off-target eyes. SUBJECTS/METHODS: We searched the MEDLINE database using keywords "axial length, corneal power, anterior chamber depth, lens thickness, white to white, and corneal thickness." We included studies that reported averages and standard deviations on eye biometry for at least 1300 eyes. Global weighted averages and standard deviations were calculated using the Cochrane method. RESULTS: Fourteen studies were included, originating from Asia (Japan, Singapore, Myanmar, Iran, South Korea, China), Europe (Germany, United Kingdom, Portugal), Australia, and North America (United States). Global ocular biometry metrics were: AL-23.49 mm ± 1.35 mm, CR-7.69 mm ± 0.28 mm, ACD-3.10 mm ± 0.47 mm, WTW-11.80 mm ± 0.42 mm, LT-4.37 mm ± 0.43 mm, and CT-544 µm ± 38 µm. Total eyes per value ranged from 19,538 to 90,814. CONCLUSIONS: We report global ocular biometry averages and standard deviations. No eyes were from studies in Africa or South America, highlighting the need to publish eye biometry data from these continents. We hope that promoting a deeper understanding of biometry values will help clinicians gain insight into surgical outcomes and drive innovations in lens calculations.

Propionibacterium acnes endophthalmitis following transplantation of contaminated Descemet's membrane endothelial keratoplasty graft.

PURPOSE: To report the clinical outcomes of a case of Propionibacterium acnes (P. acnes) endophthalmitis following Descemet's membrane endothelial keratoplasty (DMEK) surgery. OBSERVATIONS: Transplantation of non-sterile DMEK tissue led to development of a retrolenticular white plaque confirmed through PCR testing to be the result of P. acnes endophthalmitis. Intraocular antimicrobial therapy, surgical scraping of the white plaque, and repeat DMEK tissue transplantation resulted in an excellent visual outcome (20/20). CONCLUSION: This is the first reported case of P. acnes endophthalmitis following DMEK surgery. Re-transplantation may be a viable option for DMEK patients who experience post-operative endophthalmitis.

Effect of over-the-counter brimonidine tartrate 0.025% ophthalmic solution on pupil size in healthy adults.

PURPOSE: To evaluate the effect of brimonidine tartrate 0.025% ophthalmic solution on pupil size under scotopic conditions in healthy adults METHODS: Pupil size was measured in 56 eyes of 28 volunteer participants using a pupillometer under scotopic conditions. Age, gender, and iris color were recorded. Subjects using any ophthalmic medications other than artificial tears were excluded. The pupil size was subsequently measured again under scotopic conditions 60 min after instillation of brimonidine tartrate 0.025% ophthalmic solution. RESULTS: Statistically significant miosis was seen after instillation of brimonidine tartrate 0.025% (p = 0.04). Average pupil size prior to brimonidine 0.025% instillation was 7.28 ± 1.05 mm, and average pupil size after instillation of brimonidine 0.025% was 6.36 ± 1.68 mm, a reduction of - 23.7% in pupil area. Subjects with light irides demonstrated a greater miotic effect than subjects with dark irides (1.55 mm vs. 0.67 mm, p < 0.0001), with a pupil area reduction of - 37.6% and - 17.4%, respectively. The amount of miosis was independent of initial pupil size. CONCLUSIONS: Brimonidine tartrate 0.025% causes significant miosis in scotopic settings, although the effect is not as great in darker colored eyes. Further studies are needed to determine the latency and duration of the effect and whether the amount of miosis is clinically significant.

Improvement of Multiple Generations of Intraocular Lens Calculation Formulae with a Novel Approach Using Artificial Intelligence.

Purpose: Cataract surgery is the most common eye surgery. Appropriate optimization of intraocular lens (IOL) calculation formulae can result in improved patient outcomes. The purpose of this article is to describe a methodology of optimizing existing IOL formulae and develop hybrid formulae based on artificial intelligence (AI). Methods: Preoperative biometric and postoperative outcomes data were obtained from medical records at a single institution. A numeric computing environment was used to analyze these data and refine IOL formulae using supervised learning AI. The mean absolute error of each IOL formulae with and without AI enhancement was determined, as well as the number of eyes within 0.5 diopter of the predicted refraction. Results: AI algorithms improved the mean absolute error as well as number of eyes within 0.5 diopters of predicted refraction for each of the formulae tested (P < 0.05). Conclusions: A novel methodology is described that uses AI to improve existing IOL formulae. This methodology has the potential to improve clinical outcomes for cataract surgery patients. Translational Relevance: Artificial intelligence can be used to improve existing IOL formulae.

The era of artificial intelligence and virtual reality: transforming surgical education in ophthalmology.

Training the modern ophthalmic surgeon is a challenging process. Microsurgical education can benefit from innovative methods to practice surgery in low-risk simulations, assess and refine skills in the operating room through video content analytics, and learn at a distance from experienced surgeons. Developments in emerging technologies may allow us to pursue novel forms of instruction and build on current educational models. Artificial intelligence, which has already seen numerous applications in ophthalmology, may be used to facilitate surgical tracking and evaluation. Within immersive technology, growth in the space of virtual reality head-mounted displays has created intriguing possibilities for operating room simulation and observation. Here, we explore the applications of these technologies and comment on their future in ophthalmic surgical education.

Method for IOL Power Calculation in the Second Eye of Patients With Previous Keratorefractive Surgery.

PURPOSE: To describe and evaluate a method for calculating intraocular lens (IOL) power in the second operative eye of patients with a history of keratorefractive surgery. METHODS: All eyes had undergone cataract surgery by a single surgeon from 2015 to 2018. Postoperative outcomes on the first eye (eg, IOL power implanted and postoperative refractive error) were used to back calculate a "Real K" for the first eye. The difference (delta) between the second and first eye topographic simulated keratometry values was then added to the first eye Real K to calculate the second eye Real K. This Real K value was inputted into the Holladay IOL Consultant software as an "alternate K" to derive an accurate IOL power for the second eye. Mean absolute error, mean error, and percentage of eyes on target using the Delta K method were compared with results obtained with intraoperative abserrometry and the Haigis-L and Barrett True-K No History formulas. RESULTS: The mean error for the Delta K method was significantly better than the Haigis-L (P = .00001) and Barrett True-K No History (P = .027) formulas, and on par with intra-operative aberrometry (P = .25). The mean absolute error of the Delta K method was significantly better than the Haigis-L formula (P = .03). The Delta K mean absolute error was on par with intraoperative aberrometry (P = .81) and the Barrett True-K No History formula (P = .56). CONCLUSIONS: The Delta K mean absolute error is comparable to the Barrett True-K No History formula. The mean error is lower than that calculated with the Barrett True-K No History formula and comparable to intraoperative aberrometry. [J Refract Surg. 2020;36(12):826-831.].

A corneal ring ulcer.

PURPOSE: The aim of this report is to present the case of a corneal ring ulcer that presented with diagnostic and therapeutic challenges. OBSERVATIONS: A 52-year-old woman was referred by her retina doctors for ulceration of the left cornea and pain 8 days after intravitreal ranibizumab injection for diabetic macular edema. She had been treated with erythromycin ointment, topical moxifloxacin, and therapeutic soft contact lens, which she tolerated for less than 24 hours prior to referral. Visual acuity of the left eye was counting fingers. Slit lamp examination revealed a ring-shaped corneal ulcer. CONCLUSIONS: Neurotrophic corneal ulceration can mimic acanthamoeba keratitis. Neurotrophic disease should be considered in patients with underlying risk factors in whom infectious etiology cannot be confirmed and/or who don't respond to anti-microbial therapy.

Safety and Efficacy of Colored Iris Reconstruction Lens Implantation.

PURPOSE: We sought to evaluate the 1- to 9-year safety and efficacy of colored iris reconstruction lens implantation in eyes with visual disturbances caused by partial or complete aniridia. DESIGN: Prospective, interventional case series. METHODS: Thirty-eight patients were implanted with Ophtec 311 colored iris reconstruction lenses at the University of California, Los Angeles as part of a larger U.S. Food and Drug Administration clinical trial. Patients in group 1 lacked corneal pathology. Patients in group 2 patients had corneal pathology, such as endothelial failure, previous transplants, or scarring. Safety measures included loss of corrected distance visual acuity (CDVA), surgical complications, adverse events, secondary interventions, and corneal endothelial cell loss. Efficacy measures included improvement in uncorrected distance visual acuity (UDVA) and subjective visual disturbances. RESULTS: Groups 1 (n = 8) and 2 (n = 30) showed improvements in CDVA (P = .155 and .038), UDVA (P = .002 and P < .001), and subjective visual disturbance scores at year 3. Median CDVA and UDVA declined slightly for both groups after 1-2 years. Group 2 experienced more adverse events, surgical complications, and secondary interventions. Endothelial cell loss was greater for group 2 (19.7%) than group 1 (8.05%), although this difference was not statistically significant (P = .067). CONCLUSIONS: Colored iris reconstruction lens implantation improved CDVA, UDVA, and subjective visual disturbances 3 years postoperatively and beyond. Adverse events, complications, and subsequent declines in visual acuity were common, however, in these eyes with complex medical and surgical histories.

A Review of Machine Learning Techniques for Keratoconus Detection and Refractive Surgery Screening.

Various machine learning techniques have been developed for keratoconus detection and refractive surgery screening. These techniques utilize inputs from a range of corneal imaging devices and are built with automated decision trees, support vector machines, and various types of neural networks. In general, these techniques demonstrate very good differentiation of normal and keratoconic eyes, as well as good differentiation of normal and form fruste keratoconus. However, it is difficult to directly compare these studies, as keratoconus represents a wide spectrum of disease. More importantly, no public dataset exists for research purposes. Despite these challenges, machine learning in keratoconus detection and refractive surgery screening is a burgeoning field of study, with significant potential for continued advancement as imaging devices and techniques become more sophisticated.

Comparison of Endothelial Keratoplasty Techniques in Patients With Prior Glaucoma Surgery: A Case-Matched Study.

PURPOSE: To compare the outcomes of Descemet membrane endothelial keratoplasty (DMEK) with those of Descemet's stripping endothelial keratoplasty (DSEK) in eyes with prior glaucoma surgery. DESIGN: Case-matched retrospective comparative case series. METHODS: Setting/study population: 46 DMEK procedures were matched with 46 DSEK procedures at a single institution. OBSERVATION PROCEDURES: cases were matched based on preoperative visual acuity, lens status, and surgical indication. MAIN OUTCOME MEASUREMENTS: the outcome measurements included visual acuity improvement, primary and secondary graft failure, endothelial rejection, intraocular pressure (IOP) elevation, and the need for additional glaucoma intervention. RESULTS: Best-corrected visual acuity (BCVA) improved by -0.89 logMAR in the DMEK group and -0.62 logMAR in the DSEK group (P = 0.005) at 1 year follow-up. Visual acuity was significantly better in the DMEK group at postoperative months 1, 3, and 12 and at last follow-up. The percentage of patients achieving 20/40 or better best-corrected visual acuity was higher in the DMEK group at all time points, notably 47% in the DMEK group versus 15% in the DSEK group at 1 year (P = 0.002). Secondary graft failure was lower in the DMEK group (DMEK 0% vs. DSEK 17%; P = 0.006). Primary graft failure rates and rebubling rates were similar. There were no differences in the rates of postoperative IOP elevation or in the need for additional glaucoma intervention. CONCLUSIONS: In complex eyes with prior glaucoma surgery, DMEK offers faster visual recovery, better final visual acuity, and a lower rate of secondary graft failure compared to DSEK during the first postoperative year and beyond.

Orbital granulomatosis with polyangiitis masquerading as invasive fungal sinusitis.

A 55-year-old man presented with unilateral orbital inflammation and no light perception vision. Imaging revealed infiltrative enhancement of the optic nerve, orbit, and intracranial tissue. The case was suspicious for invasive fungal disease, but ultimate workup and orbital biopsy revealed granulomatosis with polyangiitis. The patient's inflammation resolved with corticosteroid and rituximab therapy. Granulomatosis with polyangiitis is a systemic vasculitis that can mimic a number of orbital pathologies.

Lessons Learned from Implantation of Morcher 50D and 96S Artificial Iris Diaphragms.

PURPOSE: To discuss problems associated with the implantation of two Morcher iris diaphragm models. METHODS: We describe the history, intraoperative complications, and postoperative complications of 5 patients with specific Morcher iris implants. RESULTS: We implanted Morcher 50D devices in 1 patient and Morcher 96S devices in 4 patients. Complications included postoperative rotation, device mis-sizing, difficult intraoperative rotation, zonular dehiscence, and intraoperative hemorrhage. CONCLUSION: Artificial iris implantation has a steep learning curve. With widespread availability on the horizon in the United States, the sharing of surgical experiences is key to achieving the best outcomes for patients.

Quantitative measurement of fixation stability during RareBit perimetry and Humphrey visual field testing.

PURPOSE: To compare fixation stability and fixation loss between the Humphrey Field Analyzer (HVF, static fixation target) and the RareBit computer-based perimeter (RBP, kinetic fixation target) during visual field testing. METHODS: Fourteen healthy volunteer subjects wore an ASL Mobile Gaze Tracker as they completed HVF 10-2 and RareBit central field tests in a random order. Fixation stability, defined as the average distance from the fixation target to the subject's gaze location, was calculated using data from the processed video capture. Fixation loss, defined as eye closure or a deviation of >20 degrees from the fixation target, was also measured. All subjects were surveyed regarding test preference. RESULTS: Use of the RBP kinetic target was associated with 18% improved fixation stability compared with the HVF static target (P=0.02). Nine of 14 study subjects demonstrated better fixation with RBP compared with HVF. Subjects demonstrated decreased fixation loss during RBP (0.9 s) compared with HVF (10.0 s) (P=0.002). Eighty-six percent of study subjects preferred RBP over HVF. CONCLUSIONS: Use of the RBP kinetic fixation target is associated with consistent fixation stability and decreased fixation loss compared with the HVF static target. This improvement in fixation stability may result from decreased perception interference (Ganzfeld, Troxler, and binocular rivalry effects), and may help account for the greater comfort reported with RBP compared with HVF.

Parallel rarebits: a novel, large-scale visual field screening method.

BACKGROUND: Rarebit perimetry (RBP) is a computer-based perimetric testing program with sensitivity and specificity for detection of visual field defects comparable to traditional automated perimetry. To make large-scale screening more efficient, we developed a parallel rarebit perimetric method to screen groups of subjects simultaneously. We then used this method to report the mean hit rate (MHR) among subjects aged 13 to 19 years. METHODS: Rarebit perimetry was installed on computers in an existing school computer laboratory. All subjects provided medical and demographic information and underwent a basic visual examination. Testing instructions were provided to groups of up to 35 subjects and rarebit perimetry was subsequently administered. Two or three test supervisors answered questions and ensured that subjects were well aligned with their test screens. Mean hit rate, reaction times, error rates and testing time were calculated, and time estimates for rarebit, frequency doubling perimetry and Humphrey 24-2 Swedish Interactive Thresholding Algorithm (SITA) fast test were compared. RESULTS: A total of 364 rarebit perimetric tests were conducted on 182 subjects. Of these, 154 subjects met our inclusion criteria for the reference range (three testing errors or less and visual acuity 6/9 or better). The average mean hit rate was 94.3 ± 4.63 per cent. Screening of 500 subjects using this parallel rarebit perimetric method would require approximately nine hours, which is far less than an estimated 77 hours required for frequency doubling perimetry C-20 screening tests or an estimated 127 hours required for Humphrey 24-2 SITA fast tests. CONCLUSION: Using our methods, rarebit perimetry can be administered in parallel to groups of subjects. The mean hit rate was comparable to that reported in previously published studies. This parallel technique may improve the efficiency of large-scale visual field screenings.

Chest wall reconstruction using implantable cross-linked porcine dermal collagen matrix (Permacol).

BACKGROUND/PURPOSE: Chest wall reconstruction in children is typically accomplished with either primary tissue repair or synthetic mesh prostheses. Primary tissue repair has been associated with high rates of scoliosis, whereas synthetic prostheses necessitate the placement of a permanent foreign body in growing children. This report describes the use of biologic mesh (Permacol; Covidien, Mansfield, MA) as an alternative to both tissue repair and synthetic prostheses in pediatric chest wall reconstruction. METHODS: A retrospective chart review was performed identifying patients undergoing chest wall reconstruction with biologic mesh at our tertiary referral children's hospital between 2007 and 2011. Data collection included patient demographics, indication for chest wall resection, number of ribs resected, the administration of postoperative radiation, length of follow-up, postoperative complications, and the degree of spinal angulation (preoperatively and at most recent follow-up). RESULTS: Five patients (age, 9.0-21.7 years; mean, 15.4 years) underwent resection for primary chest wall malignancy followed by reconstruction with biologic mesh (Permacol) during the study period. There were no postoperative mesh-related complications, and none of the patients developed clinically significant scoliosis (follow-up, 1.1-2.6 years; mean 1.9 years). CONCLUSION: Biologic mesh offers a safe and dependable alternative to both primary tissue repair and synthetic mesh in pediatric patients undergoing chest wall reconstruction.

Genetic selection reveals the role of a buried, conserved polar residue.

The burial of nonpolar surface area is known to enhance markedly the conformational stability of proteins. The contribution from the burial of polar surface area is less clear. Here, we report on the tolerance to substitution of Ser75 of bovine pancreatic ribonuclease (RNase A), a residue that has the unusual attributes of being buried, conserved, and polar. To identify variants that retain biological function, we used a genetic selection based on the intrinsic cytotoxicity of ribonucleolytic activity. Cell growth at 30 degrees C, 37 degrees C, and 44 degrees C correlated with residue size, indicating that the primary attribute of Ser75 is its small size. The side-chain hydroxyl group of Ser75 forms a hydrogen bond with a main-chain nitrogen. The conformational stability of the S75A variant, which lacks this hydrogen bond, was diminished by DeltaDeltaG = 2.5 kcal/mol. Threonine, which can reinstate this hydrogen bond, provided a catalytically active RNase A variant at higher temperatures than did some smaller residues (including aspartate), indicating that a secondary attribute of Ser75 is the ability of its uncharged side chain to accept a hydrogen bond. These results provide insight on the imperatives for the conservation of a buried polar residue.

A ribonuclease zymogen activated by the NS3 protease of the hepatitis C virus.

Translating proteases as inactive precursors, or zymogens, protects cells from the potentially lethal action of unregulated proteolytic activity. Here, we impose this strategy on bovine pancreatic ribonuclease (RNase A) by creating a zymogen in which quiescent ribonucleolytic activity is activated by the NS3 protease of the hepatitis C virus. Connecting the N-terminus and C-terminus of RNase A with a 14-residue linker was found to diminish its ribonucleolytic activity by both occluding an RNA substrate and dislocating active-site residues, which are devices used by natural zymogens. After cleavage of the linker by the NS3 protease, the ribonucleolytic activity of the RNase A zymogen increased 105-fold. Both before and after activation, the RNase A zymogen displayed high conformational stability and evasion of the endogenous ribonuclease inhibitor protein of the mammalian cytosol. Thus, the creation of ribonuclease zymogens provides a means to control ribonucleolytic activity and has the potential to provide a new class of antiviral chemotherapeutic agents.