Laser-Assisted Subepithelial Keratectomy versus Laser In Situ Keratomileusis in Myopia: A Systematic Review and Meta-Analysis

This systematic review was to compare the clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK) for myopia. Primary parameters included mean manifest refraction spherical equivalent (MRSE), MRSE within ±0.50 diopters, uncorrected visual acuity (UCVA) ≥20/20, and loss of ≥1 line of best-corrected visual acuity (BCVA). Secondary parameters included flap complications and corneal haze. Twelve clinical controlled trials were identified and used for comparing LASEK (780 eyes) to LASIK (915 eyes). There were no significant differences in visual and refractive outcomes between the two surgeries for low to moderate myopia. The incidence of loss of ≥1 line of BCVA was significantly higher in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The efficacy (MRSE and UCVA) of LASEK appeared to be a significant worsening trend in the long-term followup. Corneal haze was more severe in moderate to high myopia treated by LASEK than LASIK in the mid-term and long-term followup. The flap-related complications still occurred in LASIK, but the incidence was not significantly higher than that in LASEK. LASEK and LASIK were safe and effective for low to moderate myopia. The advantage of LASEK was the absence of flap-related complications, and such procedure complication may occur in LASIK and affect the visual results. The increased incidence of stromal haze and regression in LASEK significantly affected the visual and refractive results for high myopia.

A Physiological Neural Controller of a Muscle Fiber Oculomotor Plant in Horizontal Monkey Saccades

A neural network model of biophysical neurons in the midbrain is presented to drive a muscle fiber oculomotor plant during horizontal monkey saccades. Neural circuitry, including omnipause neuron, premotor excitatory and inhibitory burst neurons, long lead burst neuron, tonic neuron, interneuron, abducens nucleus, and oculomotor nucleus, is developed to examine saccade dynamics. The time-optimal control strategy by realization of agonist and antagonist controller models is investigated. In consequence, each agonist muscle fiber is stimulated by an agonist neuron, while an antagonist muscle fiber is unstimulated by a pause and step from the antagonist neuron. It is concluded that the neural network is constrained by a minimum duration of the agonist pulse and that the most dominant factor in determining the saccade magnitude is the number of active neurons for the small saccades. For the large saccades, however, the duration of agonist burst firing significantly affects the control of saccades. The proposed saccadic circuitry establishes a complete model of saccade generation since it not only includes the neural circuits at both the premotor and motor stages of the saccade generator, but also uses a time-optimal controller to yield the desired saccade magnitude.

Present and Possible Therapies for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the most common cause of blindness in the elderly population worldwide and is defined as a chronic, progressive disorder characterized by changes occurring within the macula reflective of the ageing process. At present, the prevalence of AMD is currently rising and is estimated to increase by a third by 2020. Although our understanding of the several components underpinning the pathogenesis of this condition has increased significantly, the treatment options for this condition remain substantially limited. In this review, we outline the existing arsenal of therapies available for AMD and discuss the additional role of further novel therapies currently under investigation for this debilitating disease.

Orbital Volumetry in Graves' Orbitopathy: Muscle and Fat Involvement in relation to Dysthyroid Optic Neuropathy

Purpose. We wanted to investigate the relative significance of fat and muscle enlargement in the development of dysthyroid optic neuropathy (DON) in Graves’ orbitopathy (GO). Methods. Preoperative coronal CT scans of 13 patients with and without DON who subsequently underwent orbital decompression were retrospectively analyzed. Thirteen patients imaged for unilateral orbital fractures served as controls. Results. The retrobulbar muscle volume was 2.1 ± 0.5 cm3 (mean ± SD) in controls, 4.3 ± 1.5 cm3 in GO without DON, and 4.7 ± 1.7 cm3 in GO with DON. The retrobulbar fat volume was 5.4 ± 1.6 cm3 in controls, 8.7 ± 8.0 cm3 in GO without DON, and 9.4 ± 3.1 cm3 in GO with DON. The muscle and fat volumes were higher in patients with GO than in controls (P<0.001), but the volumes in orbits with and without DON were not significantly different. The volume of the optic nerve were similar in the 3 groups. The number of apical, coronal 2 mm thick slices with no fat was 2.9 ± 0.9 in normal orbits, it was 4.1 ± 1.0 in GO orbits without DON and 5.3 ± 0.8 in GO orbits with DON (P=0.007). Conclusion. Apical muscle enlargement may be more important than orbital fat enlargement in the development of DON. However, the fact that apical crowding and muscle enlargement also occur in orbits without DON suggests that other factors also play a role in the development of DON.

Aspheric Intraocular Lenses Implantation for Cataract Patients with Extreme Myopia

Objective. To evaluate the postoperative visual quality of cataract patients with extreme myopia after implantation of aspheric intraocular lenses (IOLs). Methods. Thirty-three eyes were enrolled in this prospectivestudy. Eighteen eyes with an axial length longer than 28 mm were included in the extreme myopia group, and the other 15 eyes were included in the nonextreme myopia group. Phacoemulsification and aspheric IOL implantation were performed. Six months after cataract surgery, best-corrected visual acuity (BCVA), contrast sensitivity, and wavefront aberrations were measured, and subjective visual quality was assessed. Results. The BCVA improved significantly after surgery for both groups, and patients in the nonextreme myopia group achieved better postoperative BCVA due to better retinal status of the eyes. The evaluation of contrast sensitivity without glare was the same in both groups, whereas patients in the nonextreme myopia group performed better at intermediate spatial frequencies under glare conditions. The two groups did not show a significant difference in high-order aberrations. With regard to subjective visual quality, the composite scores of both groups did not differ significantly. Conclusions. Aspheric IOLs provided good visual outcomes in cataract patients with extreme myopia. These patients should undergo careful evaluation to determine the maculopathy severity level before surgery.

Effects of Ocular Dominance on Contrast Sensitivity in Middle-Aged People

Purpose. Our aim was to compare contrast sensitivity values of the dominant and nondominant eyes of healthy middle-aged subjects. Material and Methods. Ninety eyes of 45 healthy middle-aged subjects (30 males and 15 females) were included in this study. Patients were aged between 40 and 60 years, having uncorrected visual acuity (UCVA) of 20/25 or better (Snellen chart). Ocular dominance was determined by hole-in-the-card test. Functional acuity contrast testing (F.A.C.T.) was measured using the Optec 6500 vision testing system (Stereo Optical Co. Inc., Chicago, IL, USA) under both photopic and mesopic conditions. Results. At all spatial frequencies (1.5, 3, 6, 12, and 18 cpd), under mesopic conditions, the contrast sensitivity values of the dominant eyes were slightly greater than those of the nondominant eyes; but only 18 cpd spatial frequency measurements’ difference was statistically significant (P=0.035). Under photopic conditions, the contrast sensitivity values of the dominant eyes and non-dominant eyes were similar at all spatial frequencies (P>0.05). Conclusions. The photopic and mesopic contrast sensitivity values of dominant and nondominant eyes of healthy middle-aged people were similar at all spatial frequencies, except at mesopic 18 cpd spatial frequency.

Outcomes and Control Rates for I-125 Plaque Brachytherapy for Uveal Melanoma: A Community-Based Institutional Experience

Purpose. To evaluate our community-based institutional experience with plaque brachytherapy for uveal melanomas with a focus on local control rates, factors impacting disease progression, and dosimetric parameters impacting treatment toxicity. Methods and Materials. Our institution was retrospectively reviewed from 1996 to 2011; all patients who underwent plaque brachytherapy for uveal melanoma were included. Follow-up data were collected regarding local control, distant metastases, and side effects from treatment. Analysis was performed on factors impacting treatment outcomes and treatment toxicity. Results. A total of 107 patients underwent plaque brachytherapy, of which 88 had follow-up data available. Local control at 10 years was 94%. Freedom from progression (FFP) and overall survival at 10 years were 83% and 79%, respectively. On univariate analysis, there were no tumor or dosimetric treatment characteristics that were found to have a prognostic impact on FFP. Brachytherapy treatment was well tolerated, with clinically useful vision (>20/200) maintained in 64% of patients. Statistically significant dosimetric relationships were established with cataract, glaucoma, and retinopathy development (greatest P=0.05). Conclusions. Treatment with plaque brachytherapy demonstrates excellent outcomes in a community-based setting. It is well tolerated and should remain a standard of care for COMS medium sized tumors.

Optic Disc Hemorrhage after Phacoemulsification in Patients with Glaucoma

Background. Optic disk hemorrhage is known to be a risk factor for glaucoma progression. Cataract surgery by phacoemulsification results in large intraocular pressure fluctuations. We aim to investigate whether phacoemulsification is associated with optic disc hemorrhage in patients with glaucoma. Methods. This is a retrospective review of consecutive university clinic based glaucoma patients undergoing phacoemulsification alone, with at least 3 visits in the year before and at least 5 visits in the year following phacoemulsification. The presence of optic disk hemorrhage was evaluated with slit lamp biomicroscopy at each clinic visit prior to and following phacoemulsification. Results. We evaluated 158 eyes of 158 subjects; 15 (9.5%) had ODH noted at least once during the 2-year study period. Four eyes had ODH identified on postoperative day 1, for a cross-sectional prevalence of 2.5%. Fourteen ODH episodes were noted preoperatively versus 12 episodes postoperatively (P=0.68). Aspirin use was associated with ODH (P=0.015). Conclusions. Our cross-sectional study found a prevalence of ODH immediately after CE that was similar to other published rates, and our longitudinal study did not find an increase in ODH in the year after phacoemulsification when compared to the year prior to surgery.

Corneal Biomechanical Properties in Different Ocular Conditions and New Measurement Techniques

Several refractive and therapeutic treatments as well as several ocular or systemic diseases might induce changes in the mechanical resistance of the cornea. Furthermore, intraocular pressure measurement, one of the most used clinical tools, is also highly dependent on this characteristic. Corneal biomechanical properties can be measured now in the clinical setting with different instruments. In the present work, we review the potential role of the biomechanical properties of the cornea in different fields of ophthalmology and visual science in light of the definitions of the fundamental properties of matter and the results obtained from the different instruments available. The body of literature published so far provides an insight into how the corneal mechanical properties change in different sight-threatening ocular conditions and after different surgical procedures. The future in this field is very promising with several new technologies being applied to the analysis of the corneal biomechanical properties.

Retinopathy of Prematurity in Port Harcourt, Nigeria

Purpose. With many preterm babies now surviving as a result of improvement in neonatal care in Nigeria, the incidence of visual impairment/blindness as a result of retinopathy of prematurity (ROP) may rise. We describe our findings after screening starts for the first time in a 15-year-old special care baby unit so as to establish the incidence and risk factors for developing ROP. Methods. A prospective study carried out at the Special Care Baby Unit (SCBU) and Pediatric Outpatient Clinics of the University of Port Harcourt Teaching Hospital between January 1 and October 31, 2012. Fifty-three preterm babies (of 550 neonates admitted within the study period) delivered before 32 completed weeks and weighing less than 1500 g were included in the study following informed consent and the main outcome measure was the development of any stage of ROP. Results. Mean gestational age at birth was 28.98±1.38 weeks. Mean birth weight was 1411±128 g. Out of 550 babies admitted at SCBU, 87 of 100 preterms survived with 53 included in study. Twenty-five (47.2%) had different degrees of ROP with prevalence found to be 47.2%. Prevalence was higher (75%) in babies weighing <1300 g and those delivered before 30-week gestation (58%). Twenty-one (84%) had stage 1 no plus disease and 3 (12%) had stage 2 no plus disease. Only 1 (4%) had threshold disease in Zone 1. None had disease at stage 4 or 5 or AP-ROP. Receiving supplemental oxygen (χ2=6.17; P=0.01), presence of sepsis (χ2=7.47; P=0.006), multiple blood transfusions (χ2=5.11; P=0.02), and delivery by caesarian section (χ2=4.22; P=0.04) were significantly associated with development of ROP. There were no significant differences with gender, apneic spells, jaundice, or phototherapy. Conclusions and Relevance. All live infants with ROP were noted to regress spontaneously in this study. Though it may not be cost effective to acquire treatment facilities at the moment (the only child with treatable disease died), facilities for screening preterm infants displaying high risk features may be essential as smaller babies are saved.