Illumination levels in commonly used ophthalmic devices.

Pupil diameter is a key parameter for corneal and multifocal intraocular lens surgery. Many devices are dedicated to measure the pupil size, but do not specify the illumination during capture. The aim of this study was to present illumination levels in routinely used ophthalmic devices which present pupil sizes. To obtain measurements, the lux meter was placed in the chin rest in the corneal plane and the room was completely dimmed. Ten measurements were taken for each device. The illumination levels for white and red Placido disk corneal topographers were 1253.1 ± 0.2 and 329.0 ± 0.2 lux, respectively (both photopic conditions). Scheimpflug corneal tomography should be considered as a mesopic measurement (14.5 ± 0.1 lux). Optical coherence tomography and autorefractometry are scotopic measurements (0.4-0.6 lux). We postulate that producers should provide illumination levels of their devices measuring pupil size. Moreover, when mentioning a pupil size, one should consider presenting to what lighting conditions it refers to.

Agreement in non-cycloplegic and cycloplegic refraction between a photoscreener and a calibrated autorefractor.

INTRODUCTION: Photoscreeners have been shown to provide excellent measurements of the refractive error. However, whether they could be used for assessing cycloplegic refraction has not been examied. This study aimed to evaluate the agreement between cycloplegic and non-cycloplegic measurements obtained using a photoscreener and stationary autorefractor, respectively. METHODS: This study included all patients undergoing routine ophthalmic examination at the Hygeia Clinic (Poland) from June to July 2022. Each patient underwent non-cycloplegic and cycloplegic refraction assessments using the 2WIN photoscreener (Adaptica SRL, Padova, Italy) and an ARK-1 stationary autorefractor ARK-1 (Nidek Co Ltd., Tokyo, Japan), respectively. Each pair of assessments was conducted in random order, and all values were determined at a vertical distance of 12 mm. The agreement between cycloplegic and non-cycloplegic measurements was assessed using paired t-tests, Bland-Altman and ABCD ellipsoids. RESULTS: This analysis included 82 patients, of which 52 were female. Their mean age was 34.39 ± 13.13 years. The non-cycloplegic spherical equivalent (SE) did not differ significantly between the 2WIN (- 1.22 ± 2.45) and ARK-1 (- 1.19 ± 2.96) devices (p = 0.580). However, the cycloplegic SE values demonstrated more negative values with the 2WIN device (- 1.13 ± 2.19) than with the ARK-1 device (- 0.75 ± 3.03; p = 0.007). The non-cycloplegic and cycloplegic measurements were strongly correlated between the devices (r = 0.9473 and 0.9411, respectively). However, the correlation between their cycloplegic shifts in SE was low (r = 0.2645). Ellipsoid refraction aligned better non-cycloplegic (ARK-1 = 1.00; 2WIN = 1.74) than with cycloplegic refraction (ARK-1 = 1.43; 2WIN = 1.90). CONCLUSION: While the cycloplegic measurements obtained with the 2WIN photoscreener were strongly correlated with those obtained with the ARK-1 stationary autorefractor for most of the analyzed parameters, they should not be considered interchangeable.

Corneal Tomography in a Commercially Available Optical Coherence Tomography Device and Comparison With a Rotating Scheimpflug Camera.

OBJECTIVE: To compare the outcomes of corneal tomography obtained with an anterior-to-posterior segment optical coherence tomography device (Revo, Optopol Technologies Sp. z o.o.) and a rotating Scheimpflug camera (Pentacam AXL, Oculus Optikgeräte, Wetzlar, Germany). METHODS: In healthy subjects, agreement in stereometric parameters commonly used in cataract and refractive surgery was assessed. Comparison between the devices was performed using correlation coefficients, the Bland-Altman method, and a paired t test. RESULTS: Results of right eyes of 78 patients (47 women) aged 25.24±5.56 years were analyzed. The flat and steep anterior keratometry values were significantly higher for Revo than Pentacam (43.65±1.58 D vs. 42.99±1.47 D; P = 0.000, and 44.53±1.57 D vs. 43.82±1.49 D; P =0.000, respectively) and showed excellent correlation ( r =0.978 and 0.974, respectively). The results for maximal keratometry manifested a higher difference (45.89±1.69 D vs. 44.27±1.51 D for Revo and Pentacam, P =0.000) but were also strongly correlated ( r =0.871). Revo showed significantly lower corneal thickness values than Pentacam, both for apex pachymetry (535.54±32.45 vs. 550.74±31.55 µm; P =0.000) and for thinnest pachymetry (522.58±32.16 vs. 547.25±31.95 µm; P =0.000). The correlation coefficients for anterior and posterior corneal elevation at the thinnest point showed weak positive correlation ( r =0.179 and 0.185), while the correlation for corneal asphericity was moderate ( r =0.317). CONCLUSIONS: There was a significant difference between keratometric values obtained with Revo and the Pentacam AXL, although the measurements showed excellent correlation. Similar results were found for corneal thickness measurements, but not for corneal surface elevation and corneal asphericity.

Does the introduction of streamlight decrease refractive surgery operating time?

PURPOSE: The aim of the study was to analyze the time-savings associated with introduction of Streamlight™ (Alcon Laboratories, Fort Worth, TX, USA) transepithelial photorefractive keratectomy (PRK) in surface corneal ablations. METHODS: All refractive surgeries were performed using the Alcon WaveLight® EX500 at the ArtLife Clinic, Gdansk, Poland. The study included patients treated for refractive errors with transepithelial PRK between April 2019 and October 2021, who were matched with patients treated with alcohol-assisted PRK during the same period. Only results for the left eye were analyzed. RESULTS: One-hundred-five patients underwent transepithelial PRK (age 33.42 ± 8.67 years) and were matched with 105 patients that underwent alcohol-assisted PRK (age 33.05 ± 10.16 years; p = 0.11). The mean preoperative spherical equivalent refraction was - 2.04 ± 2.28 D, and - 1.9 ± 1.71 D for the transepithelial and alcohol-assisted PRK group, respectively (p = 0.20). The total surgery time was non-significantly shorter in transepithelial PRK (349.46 ± 47.83 s) than in alcohol-assisted PRK (354.93 ± 137.63 s; p = 0.7); however, the variance of surgical time was significantly lower in transepithelial PRK (p < 0.001). The laser treatment duration was greater in transepithelial PRK (41.78 ± 17.2 s) than in alcohol-assisted PRK (8.48 ± 6.12 s; p < 0.001), and so was the number of breaks during the laser treatment (0.95 ± 0.63 vs. 0.53 ± 0.88, respectively; p < 0.001). CONCLUSION: The introduction of transepithelial PRK did not bring significant time-associated savings into the refractive surgery suite.

Tear film stability in patients with symptoms of dry eye after instillation of dual polymer hydroxypropyl guar/sodium hyaluronate vs single polymer sodium hyaluronate.

PURPOSE: This study evaluated the tear film stability in patients with symptoms of dry eye after installation of dual polymer hydroxypropyl guar/sodium hyaluronate (DPHG/SH) vs single polymer SH. METHODS: Patients with recently diagnosed mild to moderate dry eye disease (OSDI score 23-32 points) were included. For each patient, the right eye was randomized to receive DPHG/SH or 0.15% SH. Just after the administration of the drop to the right eye, the fellow eye received the other eye drop. The first non-invasive Keratograph first break-up time (NIKBUT), average NIKBUT and tear meniscus height (TMH) were measured before administration of the eye drops, at 1-min, 15 min, 30 min, 60 min, 90 min, and 120 min after instillation. RESULTS: A total of 29 patients aged 22.8 ± 2.2 years participated in the study (21 women). No differences between the eye receiving DPHG/SH and single polymer SH were observed for the first NIKBUT (p = 0.45) and average NIKBUT (p = 0.24) variables at any time point. Both DPHG/SH and single polymer SH increased the TMH (p of time effect < 0.001), but with no difference between groups (p = 0.95). CONCLUSION: Both DPHG/SH and single polymer SH solutions provide lubrication of the eye surface, however, with no difference in NIKBUT and TMH evaluations for up to two hours following administration.

Technical failure rates for biometry between swept-source and older-generation optical coherence methods: a review and meta-analysis.

PURPOSE: Precise ocular measurements are fundamental for achieving excellent target refraction following both cataract surgery and refractive lens exchange. Biometry devices with swept-source optical coherence tomography (SS-OCT) employ longer wavelengths (1055-1300 nm) in order to have better penetration through opaque lenses than those with partial coherence interferometry (PCI) or low-coherence optical reflectometry (LCOR) methods. However, to date a pooled analysis showing the technical failure rate (TFR) between the methods has not been published. The aim of this study was to compare the TFR in SS-OCT and in PCI/LCOR biometry. METHODS: PubMed and Scopus were used to search the medical literature as of Feb 1, 2022. The following keywords were used in various combinations: optical biometry, partial coherence interferometry, low-coherence optical reflectometry, swept-source optical coherence tomography. Only clinical studies referring to patients undergoing routine cataract surgery, and employing at least two (PCI or LCOR vs. SS-OCT) optical methods for optical biometry in the same cohort of patients were included. RESULTS: Fourteen studies were included in the final analysis, which presented results of 2,459 eyes of at least 1,853 patients. The overall TFR of all included studies was 5.47% (95% confidence interval [CI]: 3.66-8.08%; overall I2 = 91.49%). The TFR was significantly different among the three methods (p < 0.001): 15.72% for PCI (95% CI: 10.73-22.46%; I2 = 99.62%), 6.88% for LCOR (95% CI: 3.26-13.92%; I2 = 86.44%), and 1.51% for SS-OCT (95% CI: 0.94-2.41%; I2 = 24.64%). The pooled TFR for infrared methods (PCI and LCOR) was 11.12% (95% CI: 8.45-14.52%; I2 = 78.28%), and was also significantly different to that of SS-OCT: 1.51% (95% CI: 0.94-2.41%; I2 = 24.64%; p < 0.001). CONCLUSIONS: A meta-analysis of the TFR of different biometry methods highlighted that SS-OCT biometry resulted in significantly decreased TFR compared to PCI/LCOR devices.

Evaluation of Ocular Diameter Parameters Using Swept-Source Optical Coherence Tomography.

Purpose: To investigate the iridocorneal angle-to-angle (ATA), sclera spur-to-sclera spur (STS), and white-to-white (WTW) ocular diameters and their potential influence on anterior chamber intraocular lens (ACIOL) and implantable collamer lens (ICL) sizing in Chinese subjects by using a swept-source optical coherence tomography system (SS-OCT). Design: A retrospective, observational, cross-sectional study. Methods: In 60 right eyes (60 subjects), the ATA, STS, and WTW were measured in six axes (0°-180°, 30°-210°, 60°-240°, 90°-270°, 120°-300°, and 150°-330°) using SS-OCT. The ACIOL and ICL sizes were calculated based on horizontal and vertical axes anterior segment data. A paired sample t-test was used to test the differences in each parameter across the six axes, the potential difference between each pair of parameters in a given axis, and the artificial lens size difference between the horizontal and vertical directions. Pearson's correlation analysis was used to determine the potential correlation between age and AL, WTW, STS, and ATA distances. Results: ATA and STS were the longest on the vertical and shortest on the horizontal axis, while WTW was similar on both axes. These three parameters differed only in the vertical axis (F = 4.910, p = 0.008). ATA and STS were by 0.23 ± 0.08 mm (p = 0.005) and 0.21 ± 0.08 mm wider (p = 0.010) than WTW, respectively. ICL size was 0.27 ± 0.23 mm smaller when based on the horizontal than on the vertical axis parameters (p < 0.001), while ACIOL remained similar (p = 0.709). Age correlated negatively and axial length positively with all measured values. ATA, STS, and WTW correlated positively in the same axis (all p < 0.001). Conclusions: ATA and STS were longer in the vertical than in the horizontal direction, while WTW measurements remained similar. ATA and STS diameters more accurately depicted anatomic relationships for phakic IOL sizing than WTW.

A review of late intraocular lens opacifications.

PURPOSE OF REVIEW: Phacoemulsification cataract surgery is one of the most commonly performed surgical procedure worldwide. In the majority of cases, intraocular lenses (IOLs) are implanted. Due to the increasing life expectancy and the fact that cataract surgery is performed in earlier stages, the anticipated IOL duration in the eye has increased over the last decades. The aim of this study was to review the types and describe the characteristics of late intraocular lens opacifications. RECENT FINDINGS: Calcification was the most commonly reported type of opacification in hydrophilic IOLs; it usually negatively impacted the visual function and required IOL explantation. Glistening manifested in hydrophobic acrylic lenses and was frequent in some IOL models. In most cases glistening and subsurface nanoglistenigs do not lead to a decline in visual acuity or require IOL exchange. Current studies indicate that fluid-related phenomena may induce straylight, leading to a decrease of comfort and quality of vision. SUMMARY: Several reports on late IOL opacifications have been published in recent years. In some cases, particularly in glistening, the development of the opacifications might be related to IOL aging. The influence of the fluid-related microvacuoles on the quality of vision requires further research.

EARLY DESCRIPTIONS OF VITREOUS SURGERY.

BACKGROUND: Vitreoretinal surgical techniques have evolved during the last decades because of the development and evolution of pars plana vitrectomy. The introduction of modern vitrectomy is credited to Robert Machemer (1933-2009). The aim of this review is to characterize the early developments of vitreous removal. METHODS: We used the PubMed web platform to search the terms: complications of cataract surgery, vitrectomy, vitreous body, vitreous humor, vitreous humour, vitreous tap, and vitreous transplantation. Other publications were also considered as a potential source of information when referenced in relevant articles. RESULTS: The first description of vitreous removal for treatment of eye disorders dates the 17th century; it was conducted by a Dutch surgeon Anton Nuck (1650-1692) in a case of hydrophthalmia. In English literature, the first description of vitrectomy is attributed to the American surgeon John Collins Warren (1778-1856). This method was implemented in the spontaneous dislocation of the crystalline lens. As the fibrillar structure of the vitreous once destroyed could not be regenerated, the researchers aimed to restore the chemical composition of the vitreous. For several decades, vitreous transplantation was performed for the treatment of vitreous hemorrhages and retinal detachment. CONCLUSION: Although the achievements of vitreoretinal surgery preceding Machemer's inventions are uncommonly reported, they have contributed to the concept and understanding of the treatment modalities.

Methods for achieving adequate pupil size in cataract surgery.

PURPOSE OF REVIEW: Cataract surgery is the most common surgical procedure performed worldwide. Small pupils have been an eternal challenge for cataract surgeons; insufficient pupil dilation is associated with increased complication rates, including capsule rupture, vitreous loss, iris trauma or postoperative inflammation. The aim of the current review is to present the methods for pupil dilation and the risk factors for a small pupil in a cataract patient. RECENT FINDINGS: Risk factors for intraoperative small pupil include diabetes, intraoperative floppy iris syndrome, pseudoexfoliation syndrome, receiving glaucoma medications, having undergone previous ocular surgery and iris sphincter sclerosis from aging. There is a wide range of options to manage the small pupil, including pharmacological treatment, mechanical stretching, dilation with iris hooks or pupil expanders. We recommend a stepwise approach for intraoperative pupil dilation, from pharmacological mydriasis to pupil expanders. SUMMARY: The current article discusses risk factors for a small pupil and the methods for pupil dilation in a cataract patient. Every cataract surgeon needs to be ready to cope with a small pupil, both manifesting preoperatively and intraoperatively.

Multifocal intraocular lenses and retinal diseases.

PURPOSE: Multifocal intraocular lenses (MIOLs) are often discouraged in patients with or at risk of retinal disorders (including diabetic retinopathy, age-related macular degeneration, and epiretinal membranes), as MIOLs are believed to reduce contrast sensitivity (CS). Concerns with MIOLs have also been raised in individuals with visual field defects, fixation instability or eccentric preferred retinal locations. The aim of this study is to review the influence of MIOL on quality of vision in patients with retinal diseases. METHODS: We reviewed the PubMed and Web of Science databases to identify relevant studies using the following keywords: multifocal intraocular lens, cataract surgery, cataract extraction, lens exchange, diabetic retinopathy, age-related macular degeneration, and contrast sensitivity. RESULTS: Studies evaluating CS in MIOLs present conflicting results: MIOLs either did not influence CS or resulted in worse performance under low-illuminance conditions and higher spatial frequencies when compared to monofocal IOLs. Nevertheless, MIOLs preserved CS levels within the age-matched normal range. Two studies reported that patients with concurrent retinal diseases receiving a MIOL, both unilaterally and bilaterally, reported a significant improvement in visual-related outcomes. Individuals with a monofocal IOL in one eye and a MIOL in the fellow eye reported greater subjective satisfaction with the MIOL. CONCLUSION: We were unable to find evidence suggesting that patients with retinal diseases should be advised against MIOLs. Nevertheless, more research is needed to address the aforementioned concerns and to optimize the use of MIOLs in eyes with retinal disease.

A review on the epidemiology of myopia in school children worldwide.

BACKGROUND: Due to high prevalence myopia has gained importance in epidemiological studies. Children with early onset are at particular risk of complications associated with myopia, as progression over time might result in high myopia and myopic macular degeneration. Both genetic and environmental factors play a role in the increasing prevalence of myopia. The aim of this study is to review the current literature on epidemiology and risk factors for myopia in school children (aged 6-19 years) around the world. MAIN BODY: PubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 2013 and Mar 2019 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Eighty studies were included in this literature review. Myopia prevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non-cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (73%), and high rates in North America (42%). Low prevalence under 10% was described in African and South American children. In recent studies, risk factors for myopia in schoolchildren included low outdoor time and near work, dim light exposure, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment. CONCLUSION: Low levels of outdoor activity and near work are well-established risk factors for myopia; this review provides evidence on additional environmental risk factors. New epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia. As the myopia prevalence rates in non-cycloplegic studies are overestimated, we recommend considering only cycloplegic measurements.

Ocular surgery after herpes simplex and herpes zoster keratitis.

PURPOSE: The recurrence of herpetic stromal keratitis (HSK) and herpes zoster ophthalmicus (HZO) has been reported after a variety of ocular surgeries. The aim of this study was to review the evidence on the preventive methods employed in the perioperative period in patients having undergone HSK/HZO. METHODS: The PubMed and Web of Science databases were the main resources used to conduct the medical literature search. An extensive search was performed to identify relevant articles concerning the prophylaxis against and risk of HSK/HZO recurrence in patients undergoing ocular surgery up to December 31, 2019. RESULTS: The disturbance of the corneal nerve plexus occurs during several ocular surgeries including penetrating keratoplasty, lamellar keratoplasty, corneal cross-linking, cataract surgery, as well as photorefractive and phototherapeutic procedures. Such trauma, as well as modulation of the ocular immunological response caused by steroids applied postoperatively, might engender the HSK/HZO reactivation which is not uncommon. There is strong evidence that oral prophylaxis should be recommended just after surgery in patients undergoing penetrating keratoplasty and having suffered from HSK/HZO. For other types of surgeries, the evidence is less compelling; nevertheless, a period of disease quiescence and oral prophylaxis should still be considered. CONCLUSIONS: Within the article, we discuss the available evidence for HSK/HZO prophylaxis in ocular surgery. Additional studies would be required to define the real risk of HSK/HZO recurrence following eye surgeries, and particularly cataract surgery, and to confirm the utility of perioperative HSK/HZO prophylaxis.

Early postoperative intraocular pressure elevation following cataract surgery.

PURPOSE OF REVIEW: The aim of this review was to assess the risk factors and course of postoperative intraocular pressure (IOP) increase in order to determine the optimal the treatment. RECENT FINDINGS: Early postoperative IOP elevation following cataract surgery is a frequent adverse event, and might represent 88% early postoperative complications. The risk factors for IOP elevation following phacoemulsification cataract surgery include residual viscoelastic material, resident performed surgery, glaucoma, pseudoexfoliation syndrome, axial length over 25 mm, tamsulosin intake, topical steroid application in steroid responders. A day-1 postoperative follow-up might be questioned, even in glaucoma patients, as in IOP spikes the topmost IOP elevation occurs 3-4 h postoperatively. SUMMARY: Several IOP-lowering agents have been evaluated, but none has completely prevented the occurrence of IOP spikes. We recommend applying a combination of dorzolamide/timolol and brinzolamide topically in high-risk patients, particularly with preexisting optic nerve damage. Corticosteroid cessation usually results in a reduction of the IOP to normal levels in steroid responders. Additional studies are required to assess the optimal treatment, especially in glaucoma patients.

Do we need day-1 postoperative follow-up after cataract surgery?

PURPOSE: The aim of our study was to evaluate the current nature and frequency of complications present on the first postoperative day (POD1) and to verify whether the completion of a follow-up visit at this time is justified after standard phacoemulsification cataract surgery (PCS). METHODS: We used the PubMed literature database to identify relevant studies using the following keywords: postoperative, follow-up visit, complications, outcome, intraocular pressure, IOP, intraocular pressure spikes, IOP spikes, wound leakage, wound dehiscence, intraocular lens, IOL, dislocation, exchange, phacoemulsification, cataract surgery, and cataract extraction. RESULTS: We collected and analyzed 45 articles published between 1994 and 2017. The most common complications after PCS include corneal edema, postoperative uveitis, intraocular pressure (IOP) elevation, cystoid macular edema, and posterior capsule opacification. The IOP typically peaks at 3 to 7 h after surgery; however, none of the assessed treatment regimens were sufficient to protect glaucomatous eyes from IOP spikes. The majority of postoperative complications do not require early surgical intervention. Alternatives to POD1 follow-up after PCS include a nurse-administered telephone questionnaire, shared care with non-ophthalmologists, and seeing the patients at a low threshold in cases of complaints. CONCLUSIONS: The current literature does not support the concept of a POD1 follow-up after uneventful PCS in patients without posterior synechiae or chronic/recurrent uveitis and operated on by experienced surgeons. When eliminating the POD1, visit individuals should receive topically a potent steroid (preferably prednisolone or dexamethasone). Applying a combination of topical dorzolamide/timolol and brinzolamide postoperatively in patients with glaucoma would be recommended, particularly in eyes with preexisting optic nerve damage. Eliminating the routine POD1 follow-up could result in significant health care savings without an increased risk to the patient.

Methods for evaluating quality of life and vision in patients undergoing lens refractive surgery.

PURPOSE: Cataract surgery has evolved into a procedure that generally yields the best postoperative refractive result attainable. Patients with multifocal intraocular lenses (IOLs) present higher rates of spectacle independence, although reduced intermediate vision, dysphotopsias, and a loss of image quality might also be experienced. The aim of the study was to review the methods for assessing quality of life and vision in patients undergoing lens refractive surgery in randomized controlled trials. METHODS: We reviewed the PubMed web platform to identify relevant studies using the following keywords: quality of life, quality of vision, lens surgery, lens exchange, refractive lens exchange, cataract, cataract surgery, intraocular lens, IOL, multifocal, and monovision. RESULTS: An increasing number of studies have focused on patient-reported outcomes (PROs). Only a few of the available visual function questionnaires can be regarded as useful in lens refractive surgery with multifocal IOL implantation. Many self-developed questionnaires have emerged that have not been adequately validated or found to feature properly evaluated repeatability, hampering the possibility of comparing outcomes. CONCLUSIONS: This review describes the existing PROs instruments and informs the choice of an appropriate measure in lens refractive surgery. Rasch-developed tools should be utilized for measuring quality of life and vision in patients undergoing lens refractive surgery and there is a number of highly robust tools available.

The use of povidone-iodine in ophthalmology.

PURPOSE OF REVIEW: Povidone-iodine (PVI) is a disinfectant and antiseptic agent used for preoperative preparation of the skin and mucous membranes, as well as for the treatment of contaminated wounds. Currently regimens for prophylaxis against postsurgical endophthalmitis are being modified, including a total withdrawal of antibiotics in intravitreal injections. The aim of this study was to evaluate the use of PVI in ophthalmology. RECENT FINDINGS: As a result of its broad spectrum of microbicidal activity, PVI is routinely used in ophthalmic surgery. However, various protocols are applied worldwide and within different procedures. Additional indications include prophylaxis against ophthalmia neonatorum, acute conjunctivitis, adenoviral conjunctivitis, bacterial keratitis or corneal ulcer, endophthalmitis, giant fornix syndrome, and antimicrobial prophylaxis in patients with Boston type I keratoprosthesis. SUMMARY: Despite the introduction of new antiseptics in surgery, PVI is still the preeminent antiseptic measure in ophthalmology. Its use is economically reasonable. There have been no reports of resistance to PVI or anaphylaxis with topical ophthalmic use. Furthermore, it does not induce resistance or cross-grztance to antibiotics. With these advantages the range of indications for topical use of antibiotics might decrease, with PVI as the sole perioperative antiseptic measure. Additional studies are required to assess the optimal timing, concentration and exposure time within different ophthalmic procedures.

Acute and chronic fluid misdirection syndrome: pathophysiology and treatment.

PURPOSE: To summarize our current understanding of the specific pathogenic mechanisms of the fluid misdirection syndrome and possible treatment methods. METHODS: We used the PubMed web platform to find relevant studies using the following keywords: infusion misdirection syndrome, aqueous misdirection syndrome, ciliary block, ciliovitreal block, capsular block, intraoperative fluid misdirection, subcapsular fluid entrapment, acute intraoperative rock-hard eye syndrome, positive vitreous pressure glaucoma, and malignant glaucoma. Other publications were also considered as a potential source of information when referenced in relevant articles. RESULTS: We collected and analyzed 55 articles dated from 1951 to 2016. Acute intraoperative rock-hard eye syndrome is characterized by a very shallow anterior chamber with the absence of suprachoroidal effusion or hemorrhage and no noticeable pathology of the iris-lens diaphragm. It usually occurs during uneventful phacoemulsification, particularly in hyperopic eyes. The pathophysiology of acute fluid misdirection syndrome is based on inappropriate movement of balanced salt solution via the zonular fibers. This syndrome has also been described as occurring from hours to months, or years, after the initial surgery. The pathophysiology of malignant glaucoma is based on similar mechanisms of cilio-lenticular block of aqueous flow leading to the misdirection of aqueous posteriorly into or besides the vitreous gel. Faced with these situations, vitreous decompression is required, preferably with hyaloido-capsulo-iridectomy. In phakic eyes, concomitant cataract extraction would be desirable. CONCLUSIONS: We believe both of these clinical conditions should be considered as one syndrome. We suggest the term acute fluid misdirection syndrome for the cascade of events during phacoemulsification surgery. Chronic fluid misdirection syndrome better describes the nature of malignant glaucoma.

Beginnings of Astigmatism Understanding and Management in the 19th Century.

Within the last 200 years, the perception of astigmatism has evolved from that of an infrequent and peculiar defect of the eye to a distortion almost as common as spherical refractive errors. Most of the significant findings on this condition were made in the 19th century, including the first description by Thomas Young (1773-1829) and the introduction of the treatment methods used today. The purpose of this study was to investigate the milestones in the understanding and management of astigmatism that occurred up to the year 1900. This fascinating history illustrates how knowledge evolves across time, geographical areas, and interdisciplinary boundaries. The first article looking at the use of a cylindrical lens to correct astigmatism was written by George Airy (1801-1892) in 1825. The term "astigmatism" was introduced in by William Whewell (1794-1866) in 1846. Methods for subjective and objective evaluation were subsequently established, including the introduction of a cross cylinder, keratoscope, astigmatic dial, and the development of retinoscopy and ophthalmoscopy. In the last two decades of the 19th century, the first attempt to alter the refraction in astigmatic patients by changing the shape of the cornea was made. It must be noted that diverse challenges were encountered in this field on the way to the development of a treatment, including the technical manufacture of a lens, the precise measurement of the refractive error, and understanding the optical properties of the eye. The importance of the 19th century was that interdisciplinary cooperation, such as that seen in this study, between physicists and astronomers, and mathematicians and physicians, led to the development of comprehensive knowledge on astigmatism.