Use of Techniques for Scleral and Iris Fixation in Secondary Implantation of Intraocular Lenses.

Scleral and iris fixation of intraocular lenses (IOL) are useful in the treatment of surgical or traumatic aphakia, luxation, and subluxation of IOL if the patient does not present appropriate capsular support. However, there is no consensus in the literature about which of these 2 methods is safer and better. The authors performed a literature review searching the main postoperative outcomes obtained with the use of each surgical method. Scleral and iris fixation of IOL are efficient in correction of the patients' visual acuity, even though each technique presents distinct complications which depend especially on the experience of the surgeon with the performed surgical method. It is important to understand that individuals submitted to scleral or iris fixation present previous preoperative complications in their eyes. Besides, both procedures are very complex, involving intense manipulation of the eye globe. The success rate of these surgical techniques is highly variable and has a close relation to the preoperative conditions of the patient's eye and the improvement of the surgeon's learning curve.

Short-Wavelength (Violet) Light Protects Mice From Myopia Through Cone Signaling.

Purpose: Exposure to short-wavelength light influences refractive development and inhibits myopic development in many animal models. Retinal mechanisms underlying this response remain unknown. This study used a mouse model of lens-induced myopia to evaluate the effect of different wavelength light on refractive development and dopamine levels in the retina. A possible retinal pathway is tested using a mutant mouse with dysfunctional cones. Methods: Wild-type C57BL/6J (WT) and ALS/LtJ/Gnat2cpfl3 (Gnat2-/-) mice were exposed to one of three different light conditions beginning at postnatal day 28: broad-spectrum "white" (420-680 nm), medium wavelength "green" (525 ± 40 nm), and short wavelength "violet" (400 ± 20 nm). One-half of the mice received hyperopic lens defocus. All mice were exposed to the light for 4 weeks; animals were measured weekly for refractive error and axial parameters. Retinal dopamine and the dopamine metabolite 3,4-dihydroxyphenylacetic acid were measured by HPLC. Results: In WT mice, short-wavelength violet light induced hyperopia and violet light inhibited lens-induced myopia when compared with mice exposed to white light. Hyperopia could be attributed to shallower vitreous chambers in WT animals. There were no changes in the levels of dopamine or its metabolite. In Gnat2-/- mice, violet light did not induce hyperopia or inhibit lens-induced myopia. Conclusions: These findings show that short-wavelength light slows refractive eye growth, producing hyperopic responses in mice and inhibiting lens-induced myopia. The lack of inhibition in mice with dysfunctional cones suggests that cone signaling plays a role in the hyperopic response to short-wavelength (violet) light.

Objective assessment of visual acuity: a refined model for analyzing the sweep VEP.

PURPOSE: The aim of this study was to develop a simple and reliable method for the objective assessment of visual acuity by optimizing the stimulus used in commercially available systems and by improving the methods of evaluation using a nonlinear function, the modified Ricker model. METHODS: Subjective visual acuity in the normal subjects was measured with Snellen targets, best-corrected, and in some cases also uncorrected and with plus lenses (+ 1 D, + 2 D, + 3 D). In patients, subjective visual acuity was measured best-corrected using the Freiburg Visual Acuity Test. Sweep VEP recordings to 11 spatial frequencies, with check sizes in logarithmically equidistant steps (0.6, 0.9, 1.4, 2.1, 3.3, 4.9, 7.3, 10.4, 18.2, 24.4, and 36.5 cpd), were obtained from 56 healthy subjects aged between 17 and 69 years (mean 42.5 ± 15.3 SD years) and 20 patients with diseases of the lens (n = 6), retina (n = 8) or optic nerve (n = 6). The results were fit by a multiple linear regression (2nd-order polynomial) or a nonlinear regression (modified Ricker model) and parameters compared (limiting spatial frequency (sflimiting) and the spatial frequency of the vertex (sfvertex) of the parabola for the 2nd-order polynomial fitting, and the maximal spatial frequency (sfmax), and the spatial frequency where the amplitude is 2 dB higher than the level of noise (sfthreshold) for the modified Ricker model. RESULTS: Recording with 11 spatial frequencies allows a more accurate determination of acuities above 1.0 logMAR. Tuning curves fitted to the results show that compared to the normal 2nd-order polynomial analysis, the modified Ricker model is able to describe closely the amplitudes of the sweep VEP in relation to the spatial frequencies of the presented checkerboards. In patients with a visual acuity better than about 0.5 (decimal), the predicted acuities based on the different parameters show a good match of the predicted visual acuities based on the models established in healthy volunteers to the subjective visual acuities. However, for lower visual acuities, both models tend to overestimate the visual acuity (up to ~ 0.4 logMAR), especially in patients suffering from AMD. CONCLUSIONS: Both models, the 2nd-order polynomial and the modified Ricker model performed equally well in the prediction of the visual acuity based on the amplitudes recorded using the sweep VEP. However, the modified Ricker model does not require the exclusion of data points from the fit, as necessary when fitting the 2nd-order polynomial model making it more reliable and robust against outliers, and, in addition, provides a measure for the noise of the recorded results.

Comparison of Fellow Eyes of Acute Primary Angle Closure and Phacomorphic Angle Closure.

PURPOSE: To compare anterior segment parameters in fellow eyes of acute primary angle closure (APAC) and fellow eyes of phacomorphic angle closure (AC) and to identify parameters that could be used to differentiate fellow eyes of the 2 entities. METHODS: This cross-sectional study included 55 unaffected fellow eyes of APAC, 48 unaffected fellow eyes of phacomorphic AC, and 52 eyes of control subjects. All patients underwent anterior segment optical coherence tomography imaging. Anterior chamber depth, anterior chamber area, anterior chamber width (ACW), iris thickness (IT), iris curvature, lens vault (LV), and angle parameters including angle-opening distance (AOD750) were measured in qualified images using customized software and compared among the groups using a linear mixed model. RESULTS: Fellow eyes of APAC had the smallest axial length, AOD, anterior chamber depth, anterior chamber area, ACW, and the greatest LV, and IT (P≤0.002 for all), followed by fellow eyes of phacomorphic AC, after adjustment for age, sex, and pupil diameter. IT and curvature were comparable between fellow eyes of phacomorphic AC and controls. Angle parameters had the highest area of the receiver-operator characteristic curve for discrimination of fellow eyes of APAC eyes and phacomorphic AC (0.795, P=0.001 for AOD750). In a multivariable analysis, AOD750<0.161 µm [odds ratio (OR), 23.43; P=0.001], LV>768.6 µm (OR, 16.76; P=0.001), ACW<11.07 mm (OR, 8.93; P=0.023) and younger age (P=0.001) were the factors that discriminated fellow eyes of APAC from phacomorphic AC. CONCLUSIONS: Differences in ocular biometric parameters can be detected between fellow eyes of APAC and phacomorphic AC. Narrower angle, more anteriorly displaced lens, and thicker iris are the main parameters that distinguish fellow eyes of APAC and phacomorphic AC.

Dysfunctional lens syndrome.

PURPOSE: To report the pre- and post-operative findings of a case with dysfunctional lens syndrome. METHODS: An adult patient was evaluated using iTrace aberrometer, Tomey topographer and slitlamp biomicroscopy to confirm dysfunctional lens syndrome. RESULTS: A 45-year-old male patient presented with the chief complaint of poor visual quality; uncorrected visual acuity 20/40 in the right eye, best spectacle corrected visual acuity 20/25 in the right eye with refraction Plano/-1.50 × 80 (SE = -0.75D). Pre- and post-operative root-mean-square (RMS) of total higherorder aberrations in the entire eye, the internal optics and the cornea were 0.350 & 0.257, 0.311 & 0.236 and 0.214 & 0.191 micron (µ), respectively. Also, the magnitude of preoperative total, internal and corneal coma was 0.254 µ × 222°, 0.274µ×242° and 0.097µ × 131° and postoperative values were 0.170 µ × 162°, 0.131 µ × 177°, 0.054 µ × 125°, respectively. CONCLUSION: These results show that sometime the HOAs of the internal optics, mainly crystalline lens, are not compensated by the cornea and this may cause visual discomfort in the absence of any significant cataract, this situation is known as dysfunctional lens syndrome (DLS).

Perceptual training yields rapid improvements in visually impaired youth.

Visual function demands coordinated responses to information over a wide field of view, involving both central and peripheral vision. Visually impaired individuals often seem to underutilize peripheral vision, even in absence of obvious peripheral deficits. Motivated by perceptual training studies with typically sighted adults, we examined the effectiveness of perceptual training in improving peripheral perception of visually impaired youth. Here, we evaluated the effectiveness of three training regimens: (1) an action video game, (2) a psychophysical task that combined attentional tracking with a spatially and temporally unpredictable motion discrimination task, and (3) a control video game. Training with both the action video game and modified attentional tracking yielded improvements in visual performance. Training effects were generally larger in the far periphery and appear to be stable 12 months after training. These results indicate that peripheral perception might be under-utilized by visually impaired youth and that this underutilization can be improved with only ~8 hours of perceptual training. Moreover, the similarity of improvements following attentional tracking and action video-game training suggest that well-documented effects of action video-game training might be due to the sustained deployment of attention to multiple dynamic targets while concurrently requiring rapid attending and perception of unpredictable events.

The Impact of Visual Guided Order Picking on Ocular Comfort, Ocular Surface and Tear Function.

PURPOSE: We investigated the effects of a visual picking system on ocular comfort, the ocular surface and tear function compared to those of a voice guided picking solution. DESIGN: Prospective, observational, cohort study. SETTING: Institutional. STUDY POPULATION: A total of 25 young asymptomatic volunteers performed commissioning over 10 hours on two consecutive days. MAIN OUTCOME MEASURES: The operators were guided in the picking process by two different picking solutions, either visually or by voice while their subjective symptoms and ocular surface and tear function parameters were recorded. RESULTS: The visual analogue scale (VAS) values, according to subjective dry eye symptoms, in the visual condition were significantly higher at the end of the commissioning than the baseline measurements. In the voice condition, the VAS values remained stable during the commissioning. The tear break-up time (BUT) values declined significantly in the visual condition (pre-task: 16.6 sec and post-task: 9.6 sec) in the right eyes, that were exposed to the displays, the left eyes in the visual condition showed only a minor decline, whereas the BUT values in the voice condition remained constant (right eyes) or even increased (left eyes) over the time. No significant differences in the tear meniscus height values before and after the commissioning were observed in either condition. CONCLUSION: In our study, the use of visually guided picking solutions was correlated with post-task subjective symptoms and tear film instability.

Visual outcomes in patients with zonular dialysis following cataract surgery.

PurposeTo evaluate the visual outcomes of patients with zonular dialysis following cataract surgery.Patients and methodsMedical records of all patients with documented zonular dialysis, either pre- or peri-operatively, undergoing cataract surgery between 2004-2010 at Queen Alexandra Hospital, Portsmouth, were retrospectively reviewed. Baseline demographics and biometry were analysed, and ocular co-morbidities documented. Intraoperative complications and the use of a capsular tension ring (CTR) were identified. Early and late best-corrected visual acuity (BCVA) post surgery were determined using LogMar values. Univariate and multivariate linear regression analysis was performed to determine associations with BCVA post surgery, and further subgroup analysis performed in groups determined by CTR use.ResultsThe records of 22 312 consecutive eyes undergoing cataract surgery were reviewed. The incidence of zonular dialysis was 0.50% (111 eyes). A CTR was inserted in 46 eyes. Using a multivariate linear regression model, better initial pre-operative BCVA (P=0.019), the use of a CTR (P=0.014), and the absence of vitreous loss during surgery (P=0.008, ß 0.45) were associated with improved early postoperative BCVA (mean follow-up 6.6 weeks). Better medium-term postoperative BCVA was significantly associated with preoperative BCVA (P=0.002) and the use of a CTR during surgery (P=0.004, ß -0.41).ConclusionsThe overall incidence of zonular dialysis is low. CTR use intra-operatively suggests improved early and medium-term BCVA and should be considered in all cases of zonular dialysis.

The Impact of Lens Vault on Visual Acuity and Refractive Error: Implications for Management of Primary Angle-closure Glaucoma.

PURPOSE: To investigate the relationship between lens vault (LV), visual acuity (VA), and refraction. METHODS: This was a cross-sectional study of 2047 subjects aged 50 years and older recruited from a community polyclinic. Anterior segment optical coherence tomography was performed, and customized software was used to measure LV. VA was measured using a logarithm of minimum angle of resolution chart (logMAR chart; Lighthouse Inc.), and was classified as normal (logMAR<0.3), mild impairment (0.30.6). Refraction was measured with an autorefractor machine and spherical equivalent was defined as sphere plus half cylinder. Angle closure was defined as posterior trabecular meshwork not visible for ≥2 quadrants on nonindentation gonioscopy. RESULTS: Complete data were available for 1372 subjects including 295 (21.5%) with angle closure. Angle-closure subjects were significantly older (P<0.001), with shorter axial length (P<0.001), shallower anterior chamber depth (P<0.001), and greater LV (P<0.001). There was no significant difference in VA (P=0.12) compared with those without angle closure. After adjusting for age, sex, axial length, anterior chamber depth, and spherical equivalent, there was no significant association between LV and VA (P=0.35) or between LV and spherical equivalent (P=0.06). CONCLUSIONS: The magnitude of LV was not associated with VA or spherical equivalent. Lens extraction may be a consideration in eyes with angle closure with large LV in the absence of visually significant cataract.

Femtosecond laser-assisted cataract surgery in Alport syndrome with anterior lenticonus.

PURPOSE: To report the surgical treatment of 3 eyes of 2 patients with bilateral anterior lenticonus due to Alport syndrome using femtosecond laser-assisted cataract surgery (FLACS). METHODS: Two patients with Alport syndrome presented to our department due to anterior lenticonus in both eyes. We performed FLACS with posterior chamber lens implantation in both eyes of one patient and in one eye of the other patient. Anterior segment morphologic changes were visualized with a Scheimpflug camera, and anterior segment optical coherence tomography preoperatively and 3 months after surgery. Ultrastructure of the cut capsule edges was observed with scanning electron microscopy and compared to the edge of femtosecond laser capsulotomy performed on an otherwise healthy patient with cataract (control). RESULTS: The intraocular lens (IOL) postoperative positioning parameters met the international requirements of aspherical and wavefront customized IOLs (tilt <10 degree, decentration <800 µm). Scanning electron microscopy revealed the same characteristics of the cut capsule edges in the Alport and in the control eyes. CONCLUSIONS: Femtosecond laser cataract surgery can be a safe and successful method for optical rehabilitation of anterior lenticonus in patients with Alport syndrome.

Bilateral congenital cataract with suspected lens-induced granulomatous uveitis.

A healthy newborn baby girl presented with congenital bilateral cataract. Within a few days of presenting she also developed bilateral granulomatous uveitis, a condition generally linked in newborns to congenital infections, most frequently TORCHES syndrome (toxoplasmosis, rubella, cytomegalic inclusion disease, herpesvirus, including Epstein-Barr, syphilis). Extensive investigation did not reveal any underlying etiologic mechanism. Treatment with topical and systemic steroids did not improve the uveitis. However, bilateral lens extraction resulted in a quick resolution of the uveitis.

Role of lens vault in subtypes of angle closure in Iranian subjects.

PURPOSE: The purpose of this study is to quantify anterior chamber (AC) parameters and to determine the proportion of eyes with exaggerated lens vault (LV) in different subtypes of angle closure disease using anterior segment optical coherence tomography (AS-OCT). PATIENTS AND METHODS: In this prospective study, 115 eyes of 115 Iranian patients with angle closure disease were included and categorized into three groups: (1) fellow eyes of acute angle closure (AAC; 40 eyes); (2) primary angle closure glaucoma (PACG; 39 eyes); and (3) primary angle closure suspect (PACS; 36 eyes). Complete ophthalmic examination including gonioscopy, A-scan biometry, and AS-OCT were performed. Angle parameters, LV, and iris thickness (IT) were measured using AS-OCT. An exaggerated LV was defined as LV more than one-third the distance between the corneal endothelium and a line drawn to connect the nasal and temporal scleral spurs. RESULTS: Fellow eyes of AAC had the shallower AC (P=0.01), greater iris curvature (I-curve; P=0.01), and higher LV (P=0.02) as compared with PACS and PACG eyes. There was no statistically significant difference in the mean IT at 750 µm from scleral spur among the three groups (P=0.45). Exaggerated LV was found in 67.5, 35.9, and 40% of fellow eyes of AAC, PACG, and PACS, respectively, (P=0.008) with an odds ratio of 1.92 (P=0.005) for fellow vs PACG and 1.68 (P=0.01) for fellow vs PACS. CONCLUSIONS: Exaggerated LV is highly prevalent in fellow eyes of AAC. These eyes have shallower AC depth, greater I-curve, and higher LV when compared with PACG and PACS.

Clear lens phacoemulsification in Alport syndrome: refractive results and electron microscopic analysis of the anterior lens capsule.

PURPOSE: To report the ocular findings of patients with Alport syndrome and the results of clear lens extraction in this patient group. METHODS: Twenty-three eyes of 15 patients with a diagnosis of Alport syndrome were included in this study. Clear corneal phacoemulsification and intraocular foldable lens implantation was performed in eyes with indeterminate refractive errors and/or poor visual acuity and anterior capsule samples were analyzed with electron microscopy. RESULTS: All patients had a history of hereditary nephritis and/or deafness as systemic involvement. Ophthalmologic examination revealed anterior lenticonus with high myopia and/or irregular astigmatism in all patients. The mean best-corrected visual acuity (BCVA) was 0.67 ± 0.17 logMAR (range 1.0-0.4) preoperatively and 0.17 ± 0.08 logMAR (range 0.3-0.0) postoperatively. Postoperative refractive lenticular astigmatism dramatically decreased and no ocular complications arose during the follow-up period. Transmission electron microscopic analysis of the lens capsules supported the diagnosis of Alport syndrome. CONCLUSIONS: Clear lens phacoemulsification and foldable intraocular lens implantation is a safe and effective therapeutic choice for the management of uncorrectable refractive errors and low visual acuity due to anterior lenticonus in patients with Alport syndrome.

Detection and influencing factors of capsular bag distention syndrome after cataract surgery using the Pentacam Scheimpflug system.

PURPOSE: To investigate the prevalence and morphologic changes of capsular bag distention syndrome after cataract surgery using the Pentacam and to analyze its clinical characteristics and influencing factors. DESIGN: Retrospective, cross-sectional study. METHODS: Clinical records of 239 consecutive patients who underwent cataract surgery were reviewed. Demographic data, use of intraoperative ophthalmic viscosurgical devices, type of intraocular lens implanted, axial length, and white-to-white corneal diameter were recorded. One month after surgery, dilated Scheimpflug imaging was performed. Prevalence, morphologic changes, and characteristic clinical findings of this syndrome were evaluated. RESULTS: Using Scheimpflug imaging, the prevalence of capsular bag distention syndrome was high at 26.8% (64/239), and it was possible to classify its morphologic changes into 3 types. Patients with the syndrome had poorer best-corrected visual acuity and lower satisfaction scores than those without the syndrome (P = .041 and P = .008, respectively). Although there was no significant difference observed in rate of this syndrome between the 2 ophthalmic viscosurgical devices used in our study (P > .05), implantation of 4-haptic intraocular lenses was associated with a high prevalence of the syndrome (odds ratio, 2.07; 95% confidence interval, 1.05 to 4.07; P = .0346). Patients with this syndrome had significantly longer AL (26.26 ± 2.84 mm) and white-to-white diameter (12.02 ± 0.34 mm) than those without (AL, 24.63 ± 2.89 mm; white-to-white diameter, 11.81 ± 0.32 mm; P = .0002 and P < .0001, respectively). CONCLUSIONS: Scheimpflug imaging revealed the prevalence of capsular bag distention syndrome to be high, and these patients generally had poorer visual outcomes. Intraocular lens design and dimensions of the eyes significantly influenced the prevalence of this syndrome.

Flashes, floaters and fuzz.

Flashing lights (photopsia) and floaters are common visual phenomena and patients frequently present to hospital with these symptoms. This article provides a guide for the non-specialist to the different pathologies that may result in photopsia and floaters.

Retinal ganglion cell survival and axon regeneration in WldS transgenic rats after optic nerve crush and lens injury.

BACKGROUND: We have previously shown that the slow Wallerian degeneration mutation, whilst delaying axonal degeneration after optic nerve crush, does not protect retinal ganglion cell (RGC) bodies in adult rats. To test the effects of a combination approach protecting both axons and cell bodies we performed combined optic nerve crush and lens injury, which results in both enhanced RGC survival as well as axon regeneration past the lesion site in wildtype animals. RESULTS: As previously reported we found that the Wld(S) mutation does not protect RGC bodies after optic nerve crush alone. Surprisingly, we found that Wld(S) transgenic rats did not exhibit the enhanced RGC survival response after combined optic nerve crush and lens injury that was observed in wildtype rats. RGC axon regeneration past the optic nerve lesion site was, however, similar in Wld(S) and wildtypes. Furthermore, activation of retinal glia, previously shown to be associated with enhanced RGC survival and axon regeneration after optic nerve crush and lens injury, was unaffected in Wld(S) transgenic rats. CONCLUSIONS: RGC axon regeneration is similar between Wld(S) transgenic and wildtype rats, but Wld(S) transgenic rats do not exhibit enhanced RGC survival after combined optic nerve crush and lens injury suggesting that the neuroprotective effects of lens injury on RGC survival may be limited by the Wld(S) protein.

The lens as a model for fibrotic disease.

Fibrosis affects multiple organs and is associated with hyperproliferation, cell transdifferentiation, matrix modification and contraction. It is therefore essential to discover the key drivers of fibrotic events, which in turn will facilitate the development of appropriate therapeutic strategies. The lens is an elegant experimental model to study the processes that give rise to fibrosis. The molecular and cellular organization of the lens is well defined and consequently modifications associated with fibrosis can be clearly assessed. Moreover, the avascular and non-innervated properties of the lens allow effective in vitro studies to be employed that complement in vivo systems and relate to clinical data. Using the lens as a model for fibrosis has direct relevance to millions affected by lens disorders, but also serves as a valuable experimental tool to understand fibrosis per se.