Avaliação da opacidade da cápsula posterior, após facoemulsificação e implante de lente intraocular modificada com plasma de flúor ou polietilenoglicol com coelhos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Ocorrência de opacidade de cápsula posterior em cães pós-facoemulsificação, com ou sem a utilização de lente intraocular dobrável e efeitos do Nd: Yag Laser

Pós-graduação em Cirurgia Veterinária - FCAV

Reprodutibilidade da curva de pressão intraocular de 24 horas em pacientes com glaucoma e suspeita de glaucoma

Pós-graduação em Bases Gerais da Cirurgia - FMB

Pressure-cornea-vascular index (PCVI) for predicting disease progression in normal tension glaucoma

It has been shown that the pressure-to-cornea index (PCI), which estimates the relative effects of intraocular pressure (IOP) and central corneal thickness (CCT), may differentiate between glaucoma and non-glaucoma states. The authors investigated the utility of the pressure-cornea-vascular index (PCVI) in predicting field-progression in patients with normal tension glaucoma (NTG).

Novel pressure-to-cornea index in glaucoma

BACKGROUND: Several conversion tables and formulas have been suggested to correct applanation intraocular pressure (IOP) for central corneal thickness (CCT). CCT is also thought to represent an independent glaucoma risk factor. In an attempt to integrate IOP and CCT into a unified risk factor and avoid uncertain correction for tonometric inaccuracy, a new pressure-to-cornea index (PCI) is proposed. METHODS: PCI (IOP/CCT(3)) was defined as the ratio between untreated IOP and CCT(3) in mm (ultrasound pachymetry). PCI distribution in 220 normal controls, 53 patients with normal-tension glaucoma (NTG), 76 with ocular hypertension (OHT), and 89 with primary open-angle glaucoma (POAG) was investigated. PCI's ability to discriminate between glaucoma (NTG+POAG) and non-glaucoma (controls+OHT) was compared with that of three published formulae for correcting IOP for CCT. Receiver operating characteristic (ROC) curves were built. RESULTS: Mean PCI values were: Controls 92.0 (SD 24.8), NTG 129.1 (SD 25.8), OHT 134.0 (SD 26.5), POAG 173.6 (SD 40.9). To minimise IOP bias, eyes within the same 2 mm Hg range between 16 and 29 mm Hg (16-17, 18-19, etc) were separately compared: control and NTG eyes as well as OHT and POAG eyes differed significantly. PCI demonstrated a larger area under the ROC curve (AUC) and significantly higher sensitivity at fixed 80% and 90% specificities compared with each of the correction formulas; optimum PCI cut-off value 133.8. CONCLUSIONS: A PCI range of 120-140 is proposed as the upper limit of "normality", 120 being the cut-off value for eyes with untreated pressures or=22 mm Hg. PCI may reflect individual susceptibility to a given IOP level, and thus represent a glaucoma risk factor. Longitudinal studies are needed to prove its prognostic value.

Hydrogel intraocular lens exchange: five-year experience

BACKGROUND: This study presents an evaluation of the preoperative and postoperative best corrected visual acuity (BCVA), as well as of the incidence of perioperative and postoperative complications after opacified hydrogel intraocular lens (IOL) exchange. PATIENTS AND METHODS: We exchanged opacified hydrogel IOLs (Hydroview H 60 M, Bausch ; Lomb) in 55 patients (55 eyes). Preoperative and postoperative BCVA were compared. Intraoperative and postoperative complications were recorded. Follow-up period ranged from 3 months to 24 months. RESULTS: Mean BCVA improved significantly from 0.05 preoperatively to 0.4 at 3 months postoperatively and to 0.2 at the end of the follow-up period. Forty patients (72.7 %) reported visual improvement. The procedure was uneventful in 30 eyes (54.5 %) with complete removal of the opacified IOL optics and haptics. Intraoperative complications included partial zonular dehiscence in 10 eyes (18.2 %), en block capsular bag-IOL extraction in 2 eyes (3.6 %), posterior capsule rupture in 2 eyes (3.6 %), hyphema in 3 eyes (5.5 %), retained haptics in 8 eyes (14.5 %). Postoperative complications included corneal decompensation in 5 eyes (9.1 %), cystoid macular edema in 15 eyes (27.3 %), elevated intraocular pressure in 6 eyes (10.9 %), and retinal detachment in 1 eye (1.8 %). CONCLUSIONS: Visual acuity improved after opacified hydrogel IOL exchange, however, coexistent ocular morbidity as well as the appearance of serious postoperative complications may not yield the expected results. For these reasons extensive informed consent is mandatory.

Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature

BACKGROUND Low levels of testosterone in men and changes in retinal microvascular calibre are both associated with hypertension and cardiovascular disease risk. Sex hormones are also associated with blood flow in microvascular beds which might be a key intermediate mechanism in the development of hypertension. Whether a direct association between endogenous testosterone and retinal microvascular calibre exists is currently unknown. We aimed to determine whether testosterone is independently associated with ocular perfusion via a possible association with retinal vascular calibre or whether it plays only a secondary role via its effect on blood pressure in a bi-ethnic male cohort. PROBANDS AND METHODS A total of 72 black and 81 white men (28-68 years of age) from the follow-up phase of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study were included in this sub-study. Ambulatory pulse pressure and intraocular perfusion pressures were obtained, while metabolic variables and testosterone were measured from fasting venous blood samples. Retinal vascular calibre was quantified from digital photographs using standardised protocols. RESULTS The black men revealed a poorer cardiometabolic profile and higher pulsatile pressure (>50 mm Hg), intraocular pressure and diastolic ocular perfusion pressure than the white men (p≤0.05). Only in the white men was free testosterone positively associated with retinal calibre, i.e. arterio-venular ratio and central retinal arterial calibre and inversely with central retinal venular calibre. These associations were not found in the black men, independent of whether pulse pressure and ocular perfusion pressure were part of the model. CONCLUSIONS These results suggest an independent, protective effect of testosterone on the retinal vasculature where an apparent vasodilatory response in the retinal resistance microvessels was observed in white men.

Relationship between ocular perfusion pressure and retrobulbar blood flow in patients with glaucoma with progressive damage

PURPOSE: To evaluate the relationship between ocular perfusion pressure and color Doppler measurements in patients with glaucoma. MATERIALS AND METHODS: Twenty patients with primary open-angle glaucoma with visual field deterioration in spite of an intraocular pressure lowered below 21 mm Hg, 20 age-matched patients with glaucoma with stable visual fields, and 20 age-matched healthy controls were recruited. After a 20-minute rest in a supine position, intraocular pressure and color Doppler measurements parameters of the ophthalmic artery and the central retinal artery were obtained. Correlations between mean ocular perfusion pressure and color Doppler measurements parameters were determined. RESULTS: Patients with glaucoma showed a higher intraocular pressure (P <.0008) and a lower mean ocular perfusion pressure (P <.0045) compared with healthy subjects. Patients with deteriorating glaucoma showed a lower mean blood pressure (P =.033) and a lower end diastolic velocity in the central retinal artery (P =.0093) compared with normals. Mean ocular perfusion pressure correlated positively with end diastolic velocity in the ophthalmic artery (R = 0.66, P =.002) and central retinal artery (R = 0.74, P <.0001) and negatively with resistivity index in the ophthalmic artery (R = -0.70, P =.001) and central retinal artery (R = -0.62, P =.003) in patients with deteriorating glaucoma. Such correlations did not occur in patients with glaucoma with stable visual fields or in normal subjects. The correlations were statistically significantly different between the study groups (parallelism of regression lines in an analysis of covariance model) for end diastolic velocity (P =.001) and resistivity index (P =.0001) in the ophthalmic artery, as well as for end diastolic velocity (P =.0009) and resistivity index (P =. 001) in the central retinal artery. CONCLUSIONS: The present findings suggest that alterations in ocular blood flow regulation may contribute to the progression in glaucomatous damage.

Diurnal variation of corneal shape and thickness

Purpose: To investigate associations between the diurnal variation in a range of corneal parameters, including anterior and posterior corneal topography, and regional corneal thickness. ----- Methods: Fifteen subjects had their corneas measured using a rotating Scheimpflug camera (Pentacam) every 3-7 hours over a 24-hour period. Anterior and posterior corneal axial curvature, pachymetry and anterior chamber depth were analysed. The best fitting corneal sphero-cylinder from the axial curvature, and the average corneal thickness for a series of different corneal regions were calculated. Intraocular pressure and axial length were also measured at each measurement session. Repeated measures ANOVA were used to investigate diurnal change in these parameters. Analysis of covariance was used to examine associations between the measured ocular parameters. ----- Results: Significant diurnal variation was found to occur in both the anterior and posterior corneal curvature and in the regional corneal thickness. Flattening of the anterior corneal best sphere was observed at the early morning measurement (p < 0.0001). The posterior cornea also underwent a significant steepening (p < 0.0001) and change in astigmatism 90/180° at this time. A significant swelling of the cornea (p < 0.0001) was also found to occur immediately after waking. Highly significant associations were found between the diurnal variation in corneal thickness and the changes in corneal curvature. ----- Conclusions: Significant diurnal variation occurs in the regional thickness and the shape of the anterior and posterior cornea. The largest changes in the cornea were typically evident upon waking. The observed non-uniform regional corneal thickness changes resulted in a steepening of the posterior cornea, and a flattening of the anterior cornea to occur at this time.

Water drinking influences eye length and IOP in young healthy subjects

This study aimed to investigate the influence of water loading upon intraocular pressure (IOP), ocular pulse amplitude (OPA) and axial length. Twenty one young adult subjects who were classified based on their spherical equivalent refraction as either myopes (n=11), or emmetropes (n=10) participated. Measures of IOP, OPA and ocular biometrics were collected before, and then 10, 15, 25 and 30 minutes following the ingestion of 1000 ml of water. Significant increases in both IOP and OPA were found to occur following water loading (p<0.0001), with peaks in both parameters occurring at 10 minutes after water loading (mean ± SEM increase of 2.24 ± 0.31 mmHg in IOP and 0.46 ± 0.06 mmHg in OPA). Axial length was found to reduce significantly following water loading (p=0.0005), with the largest reduction in axial length evident 10 minutes after water drinking (mean decrease 12 ± 3 µm). A significant time by refractive error group interaction (p=0.048) was found in axial length, indicative of a different pattern of change in eye length following water loading between the myopic and emmetropic populations. The largest difference in axial length change was evident at 10 minutes after water loading with a 17 ± 5 µm reduction in axial length evident in the myopes and only a 6 ± 2 µm reduction in the emmetropes. These findings illustrate significant changes in ocular parameters in young adult subjects following water loading.

Assessment of corneal dynamics with high-speed swept source optical coherence tomography combined with an air puff system

We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as the anterior lens surface. The dynamics of the measurement are driven by the biomechanical properties of the human eye as well as its intraocular pressure. Thus, the analysis of the M-scan may provide useful information about the biomechanical behavior of the anterior segment during the applanation caused by the air puff. An initial set of controlled clinical experiments are shown to comprehend the performance of the instrument and its potential applicability to further understand the eye biomechanics and intraocular pressure measurements. Limitations and possibilities of the new apparatus are discussed.

Heat strain, hydration status, and symptoms of heat illness in surface mine workers

The aim of the research program was to evaluate the heat strain, hydration status, and heat illness symptoms experienced by surface mine workers. An initial investigation involved 91 surface miners completing a heat stress questionnaire; assessing the work environment, hydration practices, and heat illness symptom experience. The key findings included 1) more than 80 % of workers experienced at least one symptom of heat illness over a 12 month period; and 2) the risk of moderate symptoms of heat illness increased with the severity of dehydration. These findings highlight a health and safety concern for surface miners, as experiencing symptoms of heat illness is an indication that the physiological systems of the body may be struggling to meet the demands of thermoregulation. To illuminate these findings a field investigation to monitor the heat strain and hydration status of surface miners was proposed. Two preliminary studies were conducted to ensure accurate and reliable data collection techniques. Firstly, a study was undertaken to determine a calibration procedure to ensure the accuracy of core body temperature measurement via an ingestible sensor. A water bath was heated to several temperatures between 23 . 51 ¢ªC, allowing for comparison of the temperature recorded by the sensors and a traceable thermometer. A positive systematic bias was observed and indicated a need for calibration. It was concluded that a linear regression should be developed for each sensor prior to ingestion, allowing for a correction to be applied to the raw data. Secondly, hydration status was to be assessed through urine specific gravity measurement. It was foreseeable that practical limitations on mine sites would delay the time between urine collection and analysis. A study was undertaken to assess the reliability of urine analysis over time. Measurement of urine specific gravity was found to be reliable up to 24 hours post urine collection and was suitable to be used in the field study. Twenty-nine surface miners (14 drillers [winter] and 15 blast crew [summer]) were monitored during a normal work shift. Core body temperature was recorded continuously. Average mean core body temperature was 37.5 and 37.4 ¢ªC for blast crew and drillers, with average maximum body temperatures of 38.0 and 37.9 ¢ªC respectively. The highest body temperature recorded was 38.4 ¢ªC. Urine samples were collected at each void for specific gravity measurement. The average mean urine specific gravity was 1.024 and 1.021 for blast crew and drillers respectively. The Heat Illness Symptoms Index was used to evaluate the experience of heat illness symptoms on shift. Over 70 % of drillers and over 80 % of blast crew reported at least one symptom. It was concluded that 1) heat strain remained within the recommended limits for acclimatised workers; and 2) the majority of workers were dehydrated before commencing their shift, and tend to remain dehydrated for the duration. Dehydration was identified as the primary issue for surface miners working in the heat. Therefore continued study focused on investigating a novel approach to monitoring hydration status. The final aim of this research program was to investigate the influence dehydration has on intraocular pressure (IOP); and subsequently, whether IOP could provide a novel indicator of hydration status. Seven males completed 90 minutes of walking in both a cool and hot climate with fluid restriction. Hydration variables and intraocular pressure were measured at baseline and at 30 minute intervals. Participants became dehydrated during the trial in the heat but maintained hydration status in the cool. Intraocular pressure progressively declined in the trial in the heat but remained relatively stable when hydration was maintained. A significant relationship was observed between intraocular pressure and both body mass loss and plasma osmolality. This evidence suggests that intraocular pressure is influenced by changes in hydration status. Further research is required to determine if intraocular pressure could be utilised as an indirect indicator of hydration status.

Ocular characteristics in myopic anisometropia

PURPOSE: To investigate the interocular symmetry of ocular optical, biometric and biomechanical characteristics between the more and less ametropic eyes of myopic anisometropes. METHODS: Thirty-four young, healthy myopic anisometropic adults (≥ 1 D spherical equivalent difference between eyes) without amblyopia or strabismus were recruited. A range of biometric and optical parameters were measured in the more and less ametropic eye of each subject including; axial length, ocular aberrations, intraocular pressure and corneal topography, thickness and biomechanics. Morphology of the anterior eye in primary and downward gaze was examined using custom software analysis of high resolution digital images. Ocular sighting dominance was assessed using the hole-in-the-card test. RESULTS: Mean absolute spherical equivalent anisometropia was 1.74 ± 0.74 D. There was a strong correlation between the degree of anisometropia and the interocular difference in axial length (r = 0.81, p < 0.001). The more and less ametropic fellow eyes displayed a high degree of interocular symmetry for the majority of biometric, biomechanical and optical parameters measured. When the level of anisometropia exceeded 1.75 D (n = 10), the more myopic eye was the dominant sighting eye in nine of these ten subjects. Subjects with greater levels of anisometropia (> 1.75 D) also showed high levels of correlation between the dominant and non-dominant eyes in their biometric, biomechanical and optical characteristics. CONCLUSIONS: Although significantly different in axial length, anisometropic eyes display a high degree of interocular symmetry for a range of anterior eye biometrics and optical parameters. For higher levels of anisometropia, the more myopic eye tends to be the dominant sighting eye.

Interocular symmetry in myopic anisometropia

Purpose: To investigate the interocular symmetry of optical, biometric and biomechanical characteristics between the fellow eyes of myopic anisometropes. Methods: Thirty-four young, healthy myopic anisometropic adults (≥ 1 D spherical equivalent difference between eyes) without amblyopia or strabismus were recruited. A range of biometric and optical parameters were measured in both eyes of each subject including; axial length, ocular aberrations, intraocular pressure (IOP), corneal topography and biomechanics. Ocular sighting dominance was also measured. Results: Mean absolute spherical equivalent anisometropia was 1.70 ± 0.74 D and there was a strong correlation between the degree of anisometropia and the interocular difference in axial length (r = 0.81, p < 0.001). The more and less myopic eyes displayed a high degree of interocular symmetry for the majority of biometric, biomechanical and optical parameters measured. When the level of anisometropia exceeded 1.75 D, the more myopic eye was more likely to be the dominant sighting eye than for lower levels of anisometropia (p=0.002). Subjects with greater levels of anisometropia (> 1.75 D) also showed high levels of correlation between the dominant and non-dominant eyes in their biometric, biomechanical and optical characteristics. Conclusions: Although significantly different in axial length, anisometropic eyes display a high degree of interocular symmetry for a range of anterior eye biometrics and optical parameters. For higher levels of anisometropia, the more myopic eye tends to be the dominant sighting eye.

Improving cyclodiode - a risk factor analysis of complications

PURPOSE: The purpose of this study is to identify risk factors for developing complications following treatment of refractory glaucoma with transscleral diode laser cyclophotocoagulation (cyclodiode), to improve the safety profile of this treatment modality. METHOD: A retrospective analysis of 72 eyes from 70 patients who were treated with cyclodiode. RESULTS: The mean pre-treatment IOP was 37.0 mmHg (SD 11.0), with a mean post-treatment reduction in intraocular pressure (IOP) of 19.8 mmHg, and a mean IOP at last follow-up of 17.1 mmHg (SD 9.7). Mean total power delivered during treatment was 156.8 Joules (SD 82.7) over a mean of 1.3 treatments (SD 0.6). Sixteen eyes (22.2% of patients) developed complications from the treatment, with the most common being hypotony, occurring in 6 patients, including 4 with neovascular glaucoma. A higher pre-treatment IOP and higher mean total power delivery also were associated with higher complications. CONCLUSIONS: Cyclodiode is an effective treatment option for glaucoma that is refractory to other treatment options. By identifying risk factors for potential complications, cyclodiode can be modified accordingly for each patient to improve safety and efficacy.