Days In Eyes Research Articles

Анализ эффективности анти-VEGF терапии диабетического макулярного отека в авитреальных глазах

Aim. To analyze the clinical efficacy of anti-VEGF therapy for diabetic macular edema (DME) in avitreal eyes. Methods. 34 patients (38 eyes) with vitreous loss and DME on the background of preproliferative diabetic retinopathy (PPDR) (18 eyes) and proliferative diabetic retinopathy (PDR) (20 eyes) were examined in the main study group. The comparison group consisted of 40 patients (40 eyes) with native vitreous body and DME on the background of PPDR (20 eyes) and PDR (20 eyes). Intravitreal injections of Lucentis 0.5 mg (IVIL) were carried out according to «three monthly injections» scheme, then – to «on demand» scheme. Results. Complete regression of DME in avitreal eyes occurred in 74 % of cases; in eyes with native vitreous body – in 75 %. The duration of postoperative reaction in eyes with vitreous loss was up to 10–14 days, compared with 1–3 days in eyes with native vitreous body. The results of the study revealed that number of IVIL was significantly less in patients with DME on the background of PPDR than PDR. Conclusion. Presence of local neuroepithelial detachment on the background of diffuse DME is prognostically favorable factor for anti-VEGF therapy. The effectiveness of IVIL in DME treatment is comparable in eyes with native vitreous body and avitreal eyes. Key words: diabetes mellitus; diabetic macular edema; preproliferative diabetic retinopathy; proliferative diabetic retinopathy; avitria; Lucentis intravitreal injections.

Клиническая эффективность лечения диабетического макулярного отека в авитричных глазах путем применения анти-VEGF терапии

Purpose. To analyze clinical efficacy of anti-VEGF therapy for diabetic macular edema (DME) in eyes with vitreous loss. Material and methods. 34 patients (38 eyes) with vitreous loss and DME were examined: on the background of pre-proliferative diabetic retinopathy (PPDR) (18 eyes) and proliferative diabetic retinopathy (PDR) (20 eyes) (the main group). The comparison group consisted of 40 patients (40 eyes) with native vitreous body and DME on the background of PPDR (20 eyes) and PDR (20 eyes). Intravitreal injection of Lucentis 0.5 mg (IVIL) was carried out according to scheme «three monthly injections», then — to scheme «on demand». Results. Complete regression of DME in eyes with vitreous loss occurred in 74 % of cases; in eyes with native vitreous body — in 75 %. The duration of postoperative reaction in eyes with vitreous loss was up to 10–14 days, compared with 1–3 days in eyes with native vitreous body. The results of the study revealed, that number of IVIL was significantly less in patients with DME on the background of PPDR, than with PDR. Conclusions. The presence of local neuroepithelial detachment on the background of diffuse DME is prognostically favorable factor for anti-VEGF therapy. The effectiveness of IVIL in treatment of DME is comparable in eyes with native vitreous body and vitreous loss. Keywords: diabetes mellitus, diabetic macular edema, pre-proliferative diabetic retinopathy, proliferative diabetic retinopathy, vitreous loss, Lucentis intravitreal injection

The Inhibitory Effect of Connective Tissue Growth Factor Antibody on Postoperative Fibrosis in a Rabbit Model of Trabeculectomy.

To compare the efficacy of subconjunctival injection of an anti-connective tissue growth factor antibody (anti-CTGF) versus mitomycin-C (MMC) and placebo in reducing scar formation in a rabbit model of trabeculectomy. A total of 14 rabbits were included. Nine rabbits underwent trabeculectomy with subconjunctival injections of either anti-CTGF antibody, MMC, or balanced salt solution (BSS), each administered in three eyes, before peritomy. The anti-CTGF group received a repeated dose of the antibody five days after surgery. All nine rabbits were euthanized on day 14; the globes were stained with hematoxylin & eosin, Masson's Trichrome, and immunohistochemistry for detecting alpha-smooth muscle (α-SMA) actin. RNA extraction was performed on five eyes of the remaining rabbits which included one eye without any surgery, one eye 5 hr after trabeculectomy without any injection, one eye five days after trabeculectomy without any injection, and two eyes five days after trabeculectomy with administration of MMC and BSS, respectively. The mean bleb area in the anti-CTGF, MMC, and control groups was 3.8 1.45, 5.9 1.4, and 3.5 1.9 mm2, respectively. Collagenous tissue was found to occupy the bleb area by 13.7%, 13.5%, and 18.5%, respectively. This ratio was significantly higher in the BSS group (P = 0.04). The expression of CTGF mRNA after 5 hr and five days in eyes undergoing trabeculectomy were significantly more pronounced as compared to the unoperated eye. The mean H-SCORE of α-SMA-immune reactive cells calculated as the grade of staining multiplied by the percentage of immune stained cells was 14.6, 10.22, and 140.58 in the anti-CTGF, MMC, and control groups, respectively. While the control eyes had a significantly higher score (Ps 0.001), the anti-CTGF and MMC groups were comparable (P = 0.87). Based on the results of this animal study, the anti-CTGF antibody injection resulted in a significant reduction in collagenous tissue and myofibroblast cells after trabeculectomy.

Intravitreal bevacizumab to treat retinopathy of prematurity in 865 eyes: a study to determine predictors of primary treatment failure and recurrence.

This study aimed to evaluate the rate and risk factors for primary failure and recurrence after intravitreal anti-VEGF injection in retinopathy of prematurity (ROP). This retrospective study was performed on 865 eyes from 441 patients with retinopathy of prematurity receiving intravitreal bevacizumab from 2012 to 2019. Medical records of patients were evaluated. Mean gestational age (GA) and birth weight of patients were 28 ± 2weeks and 1121 ± 312g, respectively. Thirty-five eyes (4.04%) had a primary failure, including 18 eyes from 187 eyes in zone 1 (9.6%) and 17 eyes from 678 eyes in zone 2 (2.5%). The mean time of retreatment was 16.64 ± 13.68days in eyes without regression ROP. The remaining 830 eyes (95.95%) were included in recurrence analysis. The recurrence occurred in 33 eyes (3.97%) of them in 20 patients, with the meantime of 77.52days after the first treatment (IVB). The presence of plus disease, history of oxygen therapy or phototherapy, and GA less than 32 were associated with significantly increased prevalence of treatment failure. The risk factors predicting recurrence are lower birth weight, zone 1 pretreatment, history of intubation, anemia, and sepsis. Intravitreal anti-VEGF is a successful treatment for ROP with a low rate of primary failure and recurrence. Awareness of risk factors for treatment failure and recurrence may help clinicians to schedule more vigilant approach in susceptible cases.

COMPETITIVE ENVIRONMENT AND MYOPIA PROGRESSION IN YOUNG PEOPLE: A PROSPECTIVE STUDY

Purpose: The aim of the study was to determine the effect of duration and distance of reading and writing over myopia progression in young people. Methods: This prospective, observational, and single-centered study was conducted on 400 eyes of 200 myopic patients. Eyes were categorized into three groups based on degree of myopia (low, moderate, and high) at the time of presentation. Cycloplegic autorefraction followed by subjective refinement of refraction was done and spherical equivalent (SE) was calculated at baseline (Time 1), and then after 6 months (Time 2), and at 1 year (Time 3). Progression of myopia was calculated as increase in SE of subject’s eye between Time 1 and Time 3. Questionnaire survey about the amount of time spent on reading and writing and their preferred working distance in centimeters for each task was filled. Task specific diopter hours per day was calculated. Multivariate analysis was done to estimate the adjusted odds ratio for time spent on reading and writing and their preferred working distance in centimeters for each task and task specific diopter hours per day for reading and writing associated with myopia progression was calculated. Results: Mean task specific reading and writing diopter hours per day in eyes with progression was 40±12 whereas that in eyes with no progression was 30±10. The observed difference was statistically highly significant (p<0.01). Task specific reading and writing diopter hours per day was significantly higher in eyes with progression as compared to no progression in low and moderate as well as in high myopes (p<0.01). Conclusion: Risk of progression of myopia was significantly (<0.05) higher in patients engaged in longer duration of reading and writing (>6 h) and at near distance (<25 cm).

Five-Year Occurrence and Management of Central Toxic Keratopathy After Femtosecond Laser-Assisted LASIK.

To report the 5-year occurrence, management, and outcomes of 12 eyes diagnosed as having central toxic keratopathy (CTK) after femtosecond laser-assisted in situ keratomileusis (FS-LASIK). A retrospective chart review was conducted on 20,622 FS-LASIK procedures performed at a single site from January 2015 to December 2019 to identify patients diagnosed as having central toxic keratopathy. Preoperative and postoperative visual acuity, refraction, and imaging were recorded and analyzed. CTK occurred in 12 eyes of 8 patients after FSLASIK. A total of 75% of eyes were diagnosed during an outbreak that happened over 2 months and the remaining 25% were considered sporadic. Five eyes were treated with flap lift and irrigation and 7 eyes were treated non-surgically. The average time to resolution of CTK in eyes that underwent flap lift and irrigation was 53 days compared to 33 days in eyes treated non-surgically. All 5 eyes treated with flap lift and irrigation ultimately achieved uncorrected distance visual acuity of 0.1 logMAR or better, whereas only 3 of 7 eyes treated non-surgically achieved the same. At the final postoperative visit, the eyes treated with flap lift and irrigation measured on average 14 µm thinner and 1.60 diopters (D) flatter than the expected postoperative pachymetry and keratometry, respectively. Those treated non-surgically were on average 28 µm thinner and 1.70 D flatter than expected. CTK is a rare complication of FS-LASIK but can occur in clusters. Although management of CTK is debated, flap lift and irrigation may lead to better visual acuity and refractive and anatomic outcomes in some cases. [J Refract Surg. 2021;37(1):25-31.].

The effects of brief high intensity light on ocular growth in chicks developing myopia vary with time of day

Evidence suggests that the relevant variable in the anti-myopigenic effect of increased time spent outdoors is the increase in light intensity. Because light is the strongest Zeitgeber, it is plausible that the effects of bright light exposure depend on time of day, and may impact circadian rhythms. In these studies, we asked whether the effects on eye growth rates and ocular rhythms of brief daily exposures to bright light differed depending on time of day in eyes developing myopia in response to form deprivation (FD) or negative lens-induced hyperopic defocus (LENS). We also studied the effects of concurrent exposures to brief hyperopic defocus and bright light. Exp. 1: Starting at 12d, chicks wearing monocular diffusers or −10 D lenses were exposed to 3 daily hours (h) of bright light (30K lux) in the morning (FD: n = 12; LENS: n = 7) or evening (FD: n = 21; LENS: n = 7) for a total of 6 exposures. Controls wore diffusers or lenses but weren't exposed to bright light ("not bright" FD: n = 14; LENS: n = 9). Exp. 2: Untreated chicks were exposed to 3 h bright light in the morning (n = 12) or evening (n = 14) for a total of 6 exposures. Controls were not exposed to bright light (n = 11). Exp. 3: Chicks were exposed to 2 h simultaneous monocular hyperopic defocus and bright light in the morning (n = 11), mid-day (n = 7) or evening (n = 8) for 5 exposures. “Not bright” lens-wearing controls were data from published work (Nickla et al., 2017). High frequency A-scan ultrasonography was done at the start and end to measure growth rates. The FD group in Exp. 1 and the morning and evening groups in Exp. 3 were measured at 6-h intervals over the final 24 h to determine parameters for the rhythms in axial length and choroidal thickness. 1. Brief bright light in the evening inhibited eye growth in eyes wearing diffusers or lenses relative to "not bright" controls(interocular differences: FD: 316 vs 468 μm, p = 0.026; LENS: 233 vs 438 μm, p = 0.03); morning bright light had no effect. There was no differential effect of time of day of exposure on the rhythm in axial length; for choroid thickness, “time” accounted for the variance between groups (2-way ANOVA interaction p = 0.027). 2. In binocularly untreated chicks, bright light in the morning had a small but significant growth stimulatory effect relative to evening exposures (803 vs 679 μm/7d; post-hoc p = 0.048). 3. Eyes exposed to simultaneous hyperopic defocus and bright light were significantly more inhibited relative to “not bright” controls for morning exposures (interocular differences: −207 vs 69 μm; p < 0.01). In conclusion, the effects of brief periods of bright light on the growth controller depended on the time of day of exposure and on the contemporaneous state ofocular growth .

Duration of room air tamponade after vitrectomy.

To evaluate the duration of room air tamponade and its associated factors. Retrospective cohort study METHODS: The present study reviewed the medical records of patients who received room air tamponade after vitrectomy between Jun 2015 and Dec 2016. The room air duration was assessed by patient interviews 2weeks after surgery. Relationships between the variables and tamponade duration were determined using logistic regression analysis. The remaining air level was determined from medical records. The room air tamponade had dissipated by 11.1 ± 1.3days after surgery. The duration was 11.2 ± 1.3days for eyes with a spared posterior capsule, longer than the duration in other eyes (10.1 ± 0.9days). Increased axial length was correlated with increased duration. Axial length and a spared posterior capsule were significantly correlated with tamponade duration. Its half-life was presumed about 3.3days. The room air seems to be absorbed at a constant rate. The data suggest that room air tamponade remains in the vitreous cavity for an average of 11.1days. Axial length and posterior capsule status were associated with duration.

Robust real-time emotion detection system using CNN architecture

As the human–robot interaction is catching eye day by day with the increase in need of automation in every field, personal robots are increasing in every area which may be coping needs of elderly people, treating autistic patients or child therapy, even in the area of babysitting the child. As robots are helping human being in all such cases, robots need to understand human emotion in order to treat human in a more customized manner. Predicting human emotion has been a difficult problem which is being solved over a decade’s time. In this paper, we have built a model which can predict human emotion from an image in real time. The network build is based on convolutional neural network which has reduced parameters by 90× from that of Vanilla CNN and also 50× from the latest state-of-the-art research carried out to the best of our knowledge. The network build is tested robustly on 8 different datasets, namely Fer2013, CK and CK+, Chicago Face Database, JAFFE Dataset, FEI face dataset, IMFDB, TFEID and custom dataset build in our laboratory having different angles, faces, backgrounds and age groups. The network achieves 74% accuracy which is an improved accuracy from the state-of-the-art accuracy with reduced computation complexity.

Preoperative anti-inflammatory treatment of diabetic patients does not improve recovery from cataract surgery when postoperatively treated with a combination of prednisolone acetate and nepafenac.

To examine preoperative anti-inflammatory treatment on recovery from cataract surgery in eyes of diabetic patients. A Prospective randomized clinical trial. One hundred and three eyes of 103 patients with diabetes undergoing routine cataract surgery were randomized (1:1) not to receive any preoperative anti-inflammatory medication or to receive preoperative topical anti-inflammatory medication with a combination of prednisolone acetate (10mg/ml) and nepafenac (1mg/ml). All eyes received postoperative anti-inflammatory combination therapy for 3weeks. Recovery from surgery was recorded by a structured home questionnaire. Clinical outcome parameters were recorded at 28days and 3months. Patient age and gender distribution, and all baseline ophthalmic and systemic parameters were comparable between the study groups. After surgery, conjunctival injection lasted 2.4±1.7days (mean±SD) and irritation of the eye 3.3±3.9days in eyes without preoperative treatment, when compared to 1.6±1.6days (p=0.067) and 2.4±4.0days (p=0.431), respectively, in eyes with preoperative treatment. At 28days, central subfield macular thickness (CSMT) increased 2.2±20.2μm in eyes without preoperative treatment, when compared 0.1±25.2μm (p=0.670) in eyes with preoperative treatment. At 3months, the respective CSMT change from baseline was -1.5±26.9μm and -3.4±26.2μm (p=0.762). None of the eyes were reported with pseudophakic cystoid macular oedema (PCME) in either group. Lack of preoperative anti-inflammatory treatment does not impair recovery from surgery or predispose diabetic patients to increased risk of PCME in eyes postoperatively treated with combination therapy of prednisolone acetate and nepafenac.

INCREASED INTRAOCULAR PRESSURE IS A RISK FACTOR FOR UNEXPLAINED VISUAL LOSS DURING SILICONE OIL ENDOTAMPONADE.

To identify the incidence rate and risk factors for unexplained visual loss associated with silicone oil endotamponade used during primary repair of macula-sparing rhegmatogenous retinal detachments. This retrospective cohort study included patients undergoing pars plana vitrectomy for primary surgical repair of macula-sparing rhegmatogenous retinal detachments in whom silicone oil endotamponade was used. The primary outcome measure was the incidence rate of unexplained visual loss and identification of risk factors associated with vision loss. Of 1,218 eyes undergoing pars plana vitrectomy for primary retinal detachment repair, 44 eyes were included for analysis. In 9 eyes (20%), an unexplained vision loss occurred. Logistic regression identified increased intraocular pressure (IOP) (prospectively defined as IOP readings during silicone oil endotamponade ≥21 mmHg on two consecutive visits or ≥25 mmHg at any time during this period) as significant predictor (odds ratio = 4.9; P = 0.04) and a classification tree ranked IOP as the most important variable for vision loss. Incidence rate of vision loss in eyes experiencing IOP increase was 4.5 vision loss events per 1,000 days at risk compared with 1 event per 1,000 days in eyes without IOP increase, yielding an incidence rate ratio of 4.5 (95% confidence interval: 1.1-17.9; P = 0.02). Sufficient control of IOP during silicone oil endotamponade for primary retinal detachment repair is warranted to reduce the probability of vision loss.

United Kingdom National Ophthalmology Database Study of Cataract Surgery: Report 3: Pseudophakic Retinal Detachment

To investigate time to pseudophakic retinal detachment (RD) after cataract surgery with posterior capsule rupture (PCR) to provide an evidence-based guide for postoperative management. Retrospective case series. A total of 61 907 eyes of 46 824 patients undergoing cataract surgery. Subanalysis of the United Kingdom Royal College of Ophthalmologists' National Ophthalmology Database from 13 sites where data on both cataract and vitreoretinal surgery were recorded on the same electronic medical records system. Overall, 61 907 cataract operations were performed between October 2006 and August 2010. Analyses were restricted to cases with at least 3 months of potential postoperative follow-up. Pseudophakic RD surgery was performed on 131 eyes of 129 patients (0.21%; 95% confidence interval [CI], 0.18%-0.25%). Of these, 36 were in eyes that had PCR during cataract surgery (3.27%; 95% CI, 2.37%-4.50%) and 95 were in eyes that did not have PCR (0.16%; 95% CI, 0.13%-0.19%). For eyes that progressed to RD surgery, the median time to pseudophakic RD surgery was 44 days for eyes with PCR, and 6.3 months for eyes without PCR. For all eyes (both with and without PCR), pseudophakic RD occurred earlier in cases performed by a trainee cataract surgeon. Pseudophakic RD occurs earlier after cataract surgery complicated by PCR. Surgeon grade is a risk factor for pseudophakic RD. Posterior vitreous detachment and RD symptoms should be discussed withpatients who undergo cataract surgery and have PCR to facilitate early attendance, and careful dilatedpostoperative examination for retinal tears is recommended in the first 2 months after surgery.

In Vivo Assessment of Pharmacologic Vitreolysis in Rabbits With the Digital Fluoroscopy System.

The purpose of this study was to demonstrate the efficacy of the digital fluoroscopy system (DFS) for the in vivo assessment of pharmacologically induced posterior vitreous detachment (PVD) and vitreous liquefaction in a rabbit model. Twenty eyes from 10 New Zealand white rabbits were divided into 5 groups. In each group, one rabbit received an intravitreal injection of 2.0 U plasmin in the right eye and 0.5 U plasmin in the left eye. Intravitreal injection of 0.1 mL balanced salt solution (BSS) was given in the right eye, and no injection was given in the left eye of another rabbit used as a control. Intraocular fluid dynamics were assessed by the DFS, using a contrast agent in each group at different time intervals (6 hours, 12 hours, 1 day, 3 days, and 7 days). After rabbits were killed, both eyes were enucleated. Scanning electron microscopy was used to confirm the morphological alterations of the vitreoretinal interface as observed in the DFS. Complete PVD was observed after 12 hours with 2.0 U plasmin injection, whereas complete PVD was observed only after 3 days in eyes injected with 0.5 U plasmin. Eyes that received BSS injection or did not receive an injection failed to show complete PVD even after 7 days. Complete vitreous liquefaction was observed after 7 days with 2.0 U plasmin injection, but no eyes with 0.5 U plasmin or BSS injection showed complete liquefaction. We could clearly confirm the presence of PVD and the degree of vitreous liquefaction by using DFS. Digital fluoroscopy system appears to be a useful tool for the evaluation of pharmacological vitreolysis in rabbits with clear in vivo visualization of PVD and vitreous liquefaction.

Vitreous hemorrhage in children and adolescents in India

To report the clinical profile, etiologies, treatment modalities, and outcomes for vitreous hemorrhage in patients <18 years of age in India. The medical records of patients presenting with vitreous hemorrhage between January 2000 and January 2010 were retrospectively reviewed. A total of 261 eyes of 246 patients (201 males) were included. Of these patients, 231 (94%) were unilateral. Trauma was the leading cause of injury in 179 eyes (68.5%); blunt trauma was more common than penetrating trauma in both males (64.7%) and females (57.7%). Wooden sticks were the most common cause of trauma (20.7%). Spontaneous causes accounted for 82 (31.5%) eyes, including 33 eyes (40%) with Eales disease, and 16 eyes (19.7%) with sequelae of retinopathy of prematurity. Trauma was most common cause of vitreous hemorrhage in all age groups, except in children <4 years of age, in whom spontaneous hemorrhage predominated. Overall, the most common management was surgery, performed in 173 (66.2%) eyes; 63 (24.1%) eyes were observed. Male sex, age >8 years, unilateral presentation, surgical treatment (P<0.001), and blunt trauma (P=0.047) were associated with severe visual loss. Mean follow-up was 636.5±802.0 days overall, 597.0±749.0 days for eyes observed and 638.8±802.6 days for eyes that underwent surgery. Posttraumatic vitreous hemorrhage comprises almost two-thirds of children and adolescents presenting with vitreous hemorrhage. Blunt trauma is more common than penetrating trauma. Male sex, age >8 years, unilateral presentation, and surgical treatment were all significantly associated with severe visual loss.

The effects of autologous serum eye drops in the treatment of ocular surface diseases : a retrospective study

AbstractPurpose To evaluate the efficiency of autologous serum eyedrops in the treatment of severe dry eye (DE) and persistent epithelial defects (PED).Methods Ninety‐seven patients with PED or DE, unresponsive to conventional treatment, were studied. Functional symptoms and slit‐lamp findings were recorded.Results The mean LogMAR visual acuity significantly improved from 1.81 (20/1291) +/‐ 9 lines before to 1.69 (20/980) +/‐ 6 lines after treatment (p = 0.01). Visual acuity increased by 2 lines or more in 29 out of 97 eyes (30%) and it decreased by 2 lines or more in 15 eyes (15%). Resolution of 3 subjective symptoms was noticed in 14 out of 97 eyes (14%), resolution of 2 in 22 (23%), resolution of 1 in 29 (30%), and no subjective improvement was found in 32 eyes (33%). Among 75 eyes with PED, ulcer healing was observed in 31 (41%) at 1 month and 61 (81%) at 3 months. In multivariate analysis only presence of limbal deficiency significantly influenced the healing time. The average time from treatment onset to ulcer healing was 213 days in eyes with limbal deficiency and 59 days in eyes with no limbal deficiency (p&lt;0.0001). Among 22 eyes with DE, improvement of subjective symptoms was observed in 8 (36%) at 1 month and 12 (55%) at 3 months. At the end of follow‐up improvement of subjective symptoms was observed in 20 (91%) eyes.Conclusion Cicatrisation of PED and improvement of DE symptoms were observed in most eyes under autologous serum.

HOW TO USE FIDUCIAL-BASED PHOTOGRAMMETRY TO TRACK LARGE-SCALE OUTDOOR MOTION

The concept for the use of vision-based tracking is that precise knowledge of the motions of many material points on the surface of interest can be obtained and used to discriminate between different types of landslides and patterns of behavior. Fiducial-based photogrammetry is inexpensive and robust, requires onetime placement of markers, and allows the user to determine temporal and spatial acquisition of digital images of marked slopes over extended time. Motions determined from analyses of serial images of day (boards and spheres) and night (LEDs) visible markers can be expressed in terms of displacement per day or weekly variation in the daily rate or in terms of total, vertical, downslope, or across-slope velocity, all depending on the needs of the user. By quantifying motion, the underlying processes driving a landslide can be understood, allowing appropriate mitigation or management strategies to be designed. Using markers that can be seen by the naked eye day and night provides communities in landslide-prone areas with a simple method to detect change in a pattern of markers on a slope.

RETINAL FUNCTION AFTER VITRECTOMY

To study retinal function after vitrectomy. Core vitrectomy was performed in 12 rabbits under standardized conditions using a vitreous cutting rate of either 600 or 1200 cuts/min. Full-field electroretinography (ERG) and multifocal electroretinography (mfERG) were performed pre- and postoperatively. Morphologic change was monitored by immunohistochemistry directed against glial fibrillary acidic protein (GFAP). Three days postoperatively, the b-wave amplitudes of all cone and rod responses of the ERG were significantly reduced in all vitrectomized eyes. At 28 days, the rod response was still reduced, but returned to normal by 58 days. No correlation was found between vitreous cutting speed and ERG findings. No reduction in the central cone function was detected in the mfERG. GFAP upregulation was found in the entire retina of vitrectomized eyes 3 days after surgery. GFAP expression was present after 28 and 58 days in eyes in which the vitreous cutting rate had been set to 600 cuts/min, but not in the 1200 cuts/min eyes. Pars plana vitrectomy transiently affects retinal function in rabbit eyes. Vitreous cutting speed is not related to the reduced function but appears inversely correlated to Müller cell activation, indicating that high-speed vitreous cutters are more lenient to the retina.

Neuroprotective Effect of Sulfhydryl Reduction in a Rat Optic Nerve Crush Model

The signaling of retinal ganglion cell (RGC) death after axotomy is partly dependent on the generation of reactive oxygen species. Shifting the RGC redox state toward reduction is protective in a dissociated mixed retinal culture model of axotomy. The hypothesis for the current study was that tris(2-carboxyethyl)phosphine (TCEP), a sulfhydryl reductant, would protect RGCs in a rat optic nerve crush model of axotomy. RGCs of postnatal day 4 to 5 Long-Evans rats were retrogradely labeled with the fluorescent tracer DiI. At approximately 8 weeks of age, the left optic nerve of each rat was crushed with forceps and, immediately after, 4 muL of TCEP (or vehicle alone) was injected into the vitreous at the pars plana to a final concentration of 6 or 60 microM. The right eye served as the control. Eight or 14 days after the crush, the animals were killed, retinal wholemounts prepared, and DiI-labeled RGCs counted. Bandeiraea simplicifolia lectin (BSL-1) was used to identify microglia. The mean number of surviving RGCs at 8 days in eyes treated with 60 microM TCEP was significantly greater than in the vehicle group (1250 +/- 156 vs. 669 +/- 109 cells/mm(2); P = 0.0082). Similar results were recorded at 14 days. Labeling was not a result of microglia phagocytosing dying RGCs. No toxic effect on RGC survival was observed with TCEP injection alone. The sulfhydryl-reducing agent TCEP is neuroprotective of RGCs in an optic nerve crush model. Sulfhydryl oxidative modification may be a final common pathway for the signaling of RGC death by reactive oxygen species after axotomy.

Diurnal variations in keratometry and refraction with intracorneal ring segments

Purpose To study refraction variations during the day in eyes with intrastromal corneal ring segments (ICRS) to correct low myopia. Setting Monticelli Clinic, Marseille, France Methods Thirteen eyes with ICRS were included in the study; the ICRS was explanted from 3 eyes because of undercorrection. The minimum follow-up in all eyes was 1 year. The same observer measured refraction and keratometry at 9:00 am, 1:00 pm, and 7:00 pm with the same autokeratorefractometer. To validate the analysis method, these eyes were compared with a group of emmetropic control eyes that had not had surgery and with a group of eyes that had photorefractive keratectomy for a similar degree of myopia. All measurements were done under the same conditions. Results After 1 year, the ICRS eyes showed a tendency toward an evening myopic shift. This was confirmed by the objective keratometry study, which showed variations closely correlated with the myopia observed. These phenomena were not observed in the other groups. Conclusion The ICRS had satisfactory predictability in eyes with up to –3.50 diopters of myopia. However, the evening myopic shift appeared similar to that observed after radial keratotomy.

Ascorbic Acid Therapy in a Thermal Burn Model of Corneal Ulceration in Rabbits

We studied the effect of topical and systemic ascorbic acid on a rabbit model of corneal ulceration produced by thermal burn. Central stromal ulceration occurred in 77% to 100% of eyes in all treatment groups. The rate of ulceration was accelerated in animals treated with systemic ascorbic acid. Ulceration began after 5.80 +/- 2.14 days in control eyes and 2.75 +/- 1.26 days in the eyes of rabbits treated with both topical and systemic ascorbic acid (P less than .02). Subconjunctival ascorbic acid alone did not affect the rate of ulceration (average onset, 6 +/- 1 days). Once ulceration occurred in animals treated with both topical and systemic ascorbic acid, the incidence of perforation and descemetocele formation was increased and that of healing was decreased. The time required for healing was not significantly altered by treatment (9.50 +/- 2.28 days for control eyes vs 5.75 +/- 2.78 days for treated eyes) (P greater than .05).