87 research outputs found
Effect of corneal light scatter on vision: a review of the literature
The cornea is the transparent connective tissue window at the front of the eye. The physiological role of the cornea is to conduct external light into the eye, focus it, together with the lens, onto the retina, and to provide rigidity to the entire eyeball. Therefore, good vision requires maintenance of the transparency and proper refractive shape of the cornea. The surface structures irregularities can be associated with wavefront aberrations and scattering errors. Light scattering in the human cornea causes a reduction of visual quality. In fact, the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye. In most cases, a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering. In fact, clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades. The measurement of corneal back scattering qualifies the degree of corneal transparency. The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency. The aim of this study was to review scattering in the human cornea and methods of measuring it
Capecitabine-Related Fourth Nerve Palsy: A Case Report
Introduction: Capecitabine has rarely been associated with neurotoxicity. Cerebellar ataxia, multifocal leukoencephalopathy, and sensorimotor peripheral neuropathy have been reported in the literature. A case of 6th nerve palsy associated with capecitabine has also been described. This article reports the first case of capecitabine-related 4th nerve palsy. Case presentation: A 72-year-old Caucasian woman was referred by the Oncology Department because she had been complaining of binocular diplopia for 6 months. The symptoms started 1 month after the introduction of capecitabine. A diagnosis of right 4th nerve palsy was made using the Parks three-step test and the Hess test. Neuroimaging analysis was negative. A slow but progressive deterioration of function was confirmed during a year of follow-up. On suspicion of a chemotherapy-related palsy, capecitabine was discontinued and switched to vinorelbine. Subsequent improvement of the clinical picture was confirmed within 2 months. Conclusion: The recognition of chemotherapy-related neurotoxicity is of paramount importance in the management of oncology patients. Once secondary invasion of the brain or the orbit by the tumor itself is ruled out, it must be suspected to prevent further deterioration
Phacoemulsification Wound Burn and Its Management
Introduction: The production of ultrasonic energy during phacoemulsification is associated with heat generation that could damage ocular tissues, particularly at the corneoscleral wound site. Case presentation: This study presents an 89-year-old patient with senile hypermature cataract and Fuchs endothelial dystrophy developing severe thermal corneoscleral injury during phacoemulsification. At presentation, visual acuity was finger count at 40 cm and there was a 1 × 2-mm area of corneal melting at the corneal tunnel with diffuse corneal oedema. After 1 month, a temporal circular corneal patch graft was applied to the corneal burn. A penetrating keratoplasty was performed 16 months after the first surgery. Conclusion: Corneal surgery, including lamellar patch grafts and full-thickness penetrating grafts, could be used, when necessary, to restore the cornea's integrity. These procedures could eliminate corneal scarring, decrease astigmatism, and improve vision in patients with phacoemulsification burns
Subretinal recombinant tissue plasminogen activator and pneumatic displacement for the management of subretinal hemorrhage occurring after anti-VEGF injections for wet AMD
We describe three cases of submacular hemorrhage that occurred two to four days after anti-VEGF intravitreal injection for occult choroidal neovascularisation in age-related macular degeneration and their management with 25 gauge pars plana vitrectomy with injection of subretinal recombinant tissue plasminogen activator (rTPA) followed by fluid-air exchange and postoperative prone position. Vitrectomy, subretinal rTPA injection and fluid-gas exchange apply as a safe and effective treatment in these cases. Functional results seem to be positive especially if surgical treatment is promptly performed
Vitreoretinal interface disorders
This article is designed to bridge the knowledge gap for Doctors, shedding light on retinal pathologies that have long dwelled in the shadows of ultra-specialization. It delves into the identification and management of atypical conditions affecting the vitreomacular interface, encompassing disorders like vitreomacular traction, epiretinal membrane, full thickness macular holes and lamellar holes. Optical coherence tomography emerges as a crucial diagnostic tool, significantly enhancing our capacity to recognize abnormalities at the vitreoretinal junction, offering clinical insights unattainable through conventional ophthalmic methods. While vitrectomy remains the predominant choice for treating these conditions, alternative approaches are being explored
Hitting the refractive target in corneal endothelial transplantation triple procedures: A systematic review
In phakic patients Descemet stripping automated endothelial keratoplasty (DSAEK) or Descemet membrane endothelial keratoplasty (DMEK) are frequently combined with phacoemulsification and intraocular lens (IOL) implantation (triple procedure). This surgery might cause a refractive shift difficult to predict. Early DMEK and DSAEK results have shown a tendency toward a hyperopic shift. Myopic postoperative refraction is typically intended to correct this postoperative refractive defect and to bring all eyes as close to emmetropia as possible. We sought to understand the mechanism underlying the hyperopization and to identify predictive factors for poorer refractive outcomes, the most suitable target refraction and IOL calculation methods in patients undergoing combined cataract extraction and lamellar endothelial corneal transplantation (DSAEK or DMEK) for endothelial dysfunctions. Of the 407 articles analyzed, only 18 were included in the analysis. A myopic target between -0.50 D and -0.75 was the most common (up to -1.50 for DSAEK triple procedures), even though no optimum target was found. Hyperopic surprises appeared more frequently in corneas that were flatter in the center than in the periphery (oblate posterior profile). Among the numerous IOL calculation formulas, there was no apparent preference
Rapidly progressing subperiosteal orbital abscess: an unexpected complication of a group-A streptococcal pharyngitis in a healthy young patient
INTRODUCTION: Complications associated to group-A streptococcal pharyingitis include non-suppurative complications such as acute rheumatic fever and glomerulonephritis and suppurative complications such as peritonsillar or retropharyngeal abscess, sinusitis, mastoiditis, otitis media, meningitis, brain abscess, or thrombosis of the intracranial venous sinuses. CASE PRESENTATION: We described a case of a 15-year-old patient with a history of acute pharyngodinia early followed by improvise fever and a progressive formation of a diffuse orbital edema, corneal hyperaemia, diplopia and severe decrease of visual acuity. The patient was surgically treated with functional endoscopic sinus surgery (FESS) after the response of a maxillofacial computed tomography scans that showed a pansinusitis complicated by a left orbital cellulites. Numerous colonies of Streptococcus pyogenes were found in the samples of pus and an antibiotic therapy with meropenem was initiated on the basis of the sensitivity test to antibiotics. The patient was finally discharged with diagnosis of left orbital cellulites with periorbital abscess, endophtalmitis and acute pansinusitis as a consequence of streptococcal pharyngitis. CONCLUSION: The case highlights the possible unusual complication of a group-A streptococcal pharyingitis in a immunocompetent child and the needing of a prompt surgical and medical approach toward the maxillofacial complications associated to the infection
LONG-TERM INTRAOCULAR PRESSURE AFTER UNCOMPLICATED PARS PLANA VITRECTOMY FOR IDIOPATHIC EPIRETINAL MEMBRANE
\u2019Purrpose:
To investigate long-term intraocular pressure trends after uncomplicated pars
plana vitrectomy for idiopathic epiretinal membrane.
Methods:
Three hundred and sixty-eight eyes of 368 consecutive patients were enrolled.
Changes in intraocular pressure 1, 3, 6, and 12 months after surgery and during the
fi
nal
follow-up visit were evaluated in vitrectomized eyes and nonvitrectomized fellow eyes.
Results:
The median follow-up period was 36 months (range 12
\u2013
92 months). Longitudinal
data analysis evidenced a 2.5-mmHg (2.2 mmHg; 2.7 mmHg, 95% con
fi
dence interval) statis-
tically signi
fi
cant difference in intraocular pressure 30 days after surgery between treated and
fellow untreated eyes, gradually recovering to a not signi
fi
cant 0.2-mmHg (
2
0.1 mmHg; 0.4
mmHg, 95% con
fi
dence interval) difference within 26 months. The incidence of late-onset
ocular hypertension was 5.7% (21 over 347, 2%; 12%, 95% con
fi
dence interval) without
difference between the treated eyes and the group control. No signi
fi
cant difference in the
incidence of late-onset ocular hypertension and
sex, lens status, or gauge of vitrectomy instru-
ments was detected. Only patient
\u2019
sagewassigni
fi
cantly higher (mean difference 4.2 years;
0.1
\u2013
8.0 years, Monte Carlo, 95% con
fi
dence interval) in those who de
veloped late-onset ocular
hypertension in the vitrectomized eye.
Conclusion:
Uncomplicated pars plana vitrectomy for idiopathic epiretinal membrane
seems not to increase the risk of late-onset ocular hypertension or open-angle glaucoma
development.
Analysis of the optical quality of intraocular lenses.
PURPOSE. To evaluate the optical quality of different intraocular lenses (IOLs). METHODS. An optical test bench and suitable software were used to assist in analysis of the optical Fourier transform (OFT) of a test image and to determine the quality of the lens in terms of spatial frequency response. The OFT was automatically converted, by means of an optical– electronic calibration procedure, into a modulation transfer function (MTF) for each lens. The passband value calculated by computer analysis of the MTF is an objective index of the lens quality. Three randomly acquired samples of 24 different models of foldable IOLs were compared. Statistical analysis was performed with twoway and one-way ANOVA for repeated measurements and with the Ryan-Einot-Gabriel-Welsch multiple F test. RESULTS. The method was demonstrated to be precise and accurate. A large range of passband values was found. Statistically significant differences between the mean passband values for different lenses were found. The lowest passband value (125.60 line pairs [lp]/mm) was measured for the IOL (Lenstec LH3000; Lenstec, Inc., St. Petersburg, FL) and the highest (191.48 lp/mm) for the Acrysof SA30AL (Alcon, Fort Worth, TX). CONCLUSIONS. Different IOLs can transmit different spectra of spatial frequencies. The best frequency response was provided by acrylic IOLs, particularly those with an asymmetrically biconvex profile. This could be due to a reduction of optical degradation provided by this type of profile. A lens with a higher frequency response should determine a better quality of vision once implanted and the frequency response should therefore be considered when choosing the intraocular lens model. (Invest Ophthalmol Vis Sci. 2004;45:2682–2690) DOI: 10.1167/iovs.03-102
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