Visual Cross-Modal Re-Organization in Children with Cochlear Implants

Background

Visual cross-modal re-organization is a neurophysiological process that occurs in deafness. The intact sensory modality of vision recruits cortical areas from the deprived sensory modality of audition. Such compensatory plasticity is documented in deaf adults and animals, and is related to deficits in speech perception performance in cochlear-implanted adults. However, it is unclear whether visual cross-modal re-organization takes place in cochlear-implanted children and whether it may be a source of variability contributing to speech and language outcomes. Thus, the aim of this study was to determine if visual cross-modal re-organization occurs in cochlear-implanted children, and whether it is related to deficits in speech perception performance.

Methods

Visual evoked potentials (VEPs) were recorded via high-density EEG in 41 normal hearing children and 14 cochlear-implanted children, aged 5–15 years, in response to apparent motion and form change. Comparisons of VEP amplitude and latency, as well as source localization results, were conducted between the groups in order to view evidence of visual cross-modal re-organization. Finally, speech perception in background noise performance was correlated to the visual response in the implanted children.

Results

Distinct VEP morphological patterns were observed in both the normal hearing and cochlear-implanted children. However, the cochlear-implanted children demonstrated larger VEP amplitudes and earlier latency, concurrent with activation of right temporal cortex including auditory regions, suggestive of visual cross-modal re-organization. The VEP N1 latency was negatively related to speech perception in background noise for children with cochlear implants.

Conclusion

Our results are among the first to describe cross modal re-organization of auditory cortex by the visual modality in deaf children fitted with cochlear implants. Our findings suggest that, as a group, children with cochlear implants show evidence of visual cross-modal recruitment, which may be a contributing source of variability in speech perception outcomes with their implant.     

Cataract Surgery Visual Outcomes and Associated Risk Factors in Secondary Level Eye Care Centers of L V Prasad Eye Institute,India

Purpose

To evaluate cataract surgery visual outcomes and associated risk factors in rural secondary level eye care centers of L V Prasad Eye Institute (LVPEI), India.

Methods

The Eye Health pyramid of LVPEI has a network of rural secondary care centres (SCs) and attached vision centres (VCs) that provide high quality comprehensive eye care with permanent infrastructure to the most disadvantaged sections of society. The most common procedure performed at SCs is cataract surgery. We audited the outcome of a random sample of 2,049 cataract surgeries done from October 2009-March 2010 at eight rural SCs. All patients received a comprehensive ophthalmic examination, both before and after surgery. The World Health Organization recommended cataract surgical record was used for data entry. Visual outcomes were measured at discharge, 1–3 weeks and 4–11 weeks follow up visits. Poor outcome was defined as best corrected visual acuity <6/18.

Results

Mean age was 61.8 years (SD: 8.9 years) and 1,133 (55.3%) surgeries were performed on female patients. Pre-existing ocular co-morbidity was present in 165 patients (8.1%). The most common procedure was small incision cataract surgery (SICS) with intraocular lens (IOL) implantation (91.8%). Intraoperative complications were seen in 29 eyes (1.4%). At the 4–11 weeks follow-up visit, based on presenting visual acuity (PVA), 61.8% had a good outcome and based on best-corrected visual acuity (BCVA), 91.7% had a good outcome. Based on PVA and BCVA, those with less than 6/60 were only 2.9% and 1.6% respectively. Using multivariable analysis, poor visual outcomes were significantly higher in patients aged ≥70 (OR 4.63; 95% CI 1.61, 13.30), in females (OR 1.58; 95% CI 1.04, 2.41), those with preoperative comorbidities (odds ratio 4.68; 95% CI 2.90, 7.57), with intraoperative complications (OR 8.01; 95% CI 2.91, 22.04), eyes that underwent no IOL or anterior chamber-IOL (OR 12.63; 95% CI 2.65, 60.25) and those undergoing extracapsular cataract extraction (OR 9.39; 95% CI 1.18, 74.78).

Conclusions

This study demonstrates that quality cataract surgeries can be achieved at rural SCs. The concept of the LVPEI SCs can be applied to other developing countries, allowing rural patients to attain better vision through cataract surgery. Despite improvements in quality of cataract surgery, gender discrimination in terms of outcome continues to be an issue and needs further investigation.     

Difference in Outcomes between First-Operated vs. Fellow-Operated Eyes in Patients Undergoing Bilateral Trabeculectomies

Main Objective

To compare the course and outcome of first- and fellow-operated eyes in patients who underwent bilateral trabeculectomies and to investigate the factors associated with the difference.

Methods

Preoperative characteristics, including the interval between surgeries, were compared between the first- and fellow-operated eyes in 42 patients who underwent bilateral trabeculectomies. Postoperative intraocular pressure and bleb vascularity, using postoperative anterior segment photos, were compared at various time points between the first- and fellow-operated eyes. Surgical success was evaluated at 1 year after surgery and at the final follow-up. Factors affecting the difference between the first and fellow eyes were analyzed.

Results

There was no significant difference in success or failure rates at 1 year postoperatively and at the final follow-up between the first- and fellow-operated eyes. Early postoperative IOP and the degree of bleb vascularity were higher in the fellow-operated eyes (P = 0.001 and 0.003, respectively at week 1 postoperative). The difference in IOP between the first- and fellow-operated eyes was greater in patients whose interval between surgeries was shorter than 3 weeks (P = 0.026).

Conclusions

In patients undergoing bilateral trabeculectomies, early postoperative IOP was higher in the fellow-operated eyes than the first-operated eyes; the difference was greater when the interval between surgeries was shorter. The first-operated eye may influence the early postoperative inflammatory response in the fellow-operated eye. Our findings have clinical implications for planning treatment of patients who may need bilateral surgery.     

Improved Visualization of Intracranial Vessels with Intraoperative Coregistration of Rotational Digital Subtraction Angiography and Intraoperative 3D Ultrasound

Introduction

Ultrasound can visualize and update the vessel status in real time during cerebral vascular surgery. We studied the depiction of parent vessels and aneurysms with a high-resolution 3D intraoperative ultrasound imaging system during aneurysm clipping using rotational digital subtraction angiography as a reference.

Methods

We analyzed 3D intraoperative ultrasound in 39 patients with cerebral aneurysms to visualize the aneurysm intraoperatively and the nearby vascular tree before and after clipping. Simultaneous coregistration of preoperative subtraction angiography data with 3D intraoperative ultrasound was performed to verify the anatomical assignment.

Results

Intraoperative ultrasound detected 35 of 43 aneurysms (81%) in 39 patients. Thirty-nine intraoperative ultrasound measurements were matched with rotational digital subtraction angiography and were successfully reconstructed during the procedure. In 7 patients, the aneurysm was partially visualized by 3D-ioUS or was not in field of view. Post-clipping intraoperative ultrasound was obtained in 26 and successfully reconstructed in 18 patients (69%) despite clip related artefacts. The overlap between 3D-ioUS aneurysm volume and preoperative rDSA aneurysm volume resulted in a mean accuracy of 0.71 (Dice coefficient).

Conclusions

Intraoperative coregistration of 3D intraoperative ultrasound data with preoperative rotational digital subtraction angiography is possible with high accuracy. It allows the immediate visualization of vessels beyond the microscopic field, as well as parallel assessment of blood velocity, aneurysm and vascular tree configuration. Although spatial resolution is lower than for standard angiography, the method provides an excellent vascular overview, advantageous interpretation of 3D-ioUS and immediate intraoperative feedback of the vascular status. A prerequisite for understanding vascular intraoperative ultrasound is image quality and a successful match with preoperative rotational digital subtraction angiography.     

Acute Zonal Occult Outer Retinopathy in Japanese Patients: Clinical Features,Visual Function,and Factors Affecting Visual Function

Purpose

To evaluate the clinical features and investigate their relationship with visual function in Japanese patients with acute zonal occult outer retinopathy (AZOOR).

Methods

Fifty-two eyes of 38 Japanese AZOOR patients (31 female and 7 male patients; mean age at first visit, 35.0 years; median follow-up duration, 31 months) were retrospectively collected: 31 untreated eyes with good visual acuity and 21 systemic corticosteroid-treated eyes with progressive visual acuity loss. Variables affecting the logMAR values of best-corrected visual acuity (BCVA) and the mean deviation (MD) on Humphrey perimetry at initial and final visits were examined using multiple stepwise linear regression analysis.

Results

In untreated eyes, the mean MD at the final visit was significantly higher than that at the initial visit (P = 0.00002). In corticosteroid-treated eyes, the logMAR BCVA and MD at the final visit were significantly better than the initial values (P = 0.007 and P = 0.02, respectively). The final logMAR BCVA was 0.0 or less in 85% of patients. Variables affecting initial visual function were moderate anterior vitreous cells, myopia severity, and a-wave amplitudes on electroretinography; factors affecting final visual function were the initial MD values, female sex, moderate anterior vitreous cells, and retinal atrophy.

Conclusions

Our data indicated that visual functions in enrolled patients significantly improved spontaneously or after systemic corticosteroids therapy, suggesting that Japanese patients with AZOOR have good visual outcomes during the follow-up period of this study. Furthermore, initial visual field defects, gender, anterior vitreous cells, and retinal atrophy affected final visual functions in these patients.     

Retinal Neurodegeneration in Wilson’s Disease Revealed by Spectral Domain Optical Coherence Tomography

Background/Objective

In addition to cirrhosis of the liver, Wilson’s disease leads to copper accumulation and widespread degeneration of the nervous system. Delayed visual evoked potentials (VEPs) suggest changes to the visual system and potential structural changes of the retina.

Methods

We used the latest generation of spectral domain optical coherence tomography to assess the retinal morphology of 42 patients with Wilson’s disease and 76 age- and sex-matched controls. We measured peripapillary retinal nerve fiber layer (RNFL) thickness and total macular thickness and manually segmented all retinal layers in foveal scans of 42 patients with Wilson’s disease and 76 age- and sex-matched controls. The results were compared with VEPs and clinical parameters.

Results

The mean thickness of the RNFL, paramacular region, retinal ganglion cell/inner plexiform layer and inner nuclear layer was reduced in Wilson’s disease. VEPs were altered with delayed N75 and P100 latencies, but the N140 latency and amplitude was unchanged. An analysis of the laboratory parameters indicated that the serum concentrations of copper and caeruloplasmin positively correlated with the thickness of the outer plexiform layer and with N75 and P100 VEP latencies.

Conclusion

Neuronal degeneration in Wilson’s disease involves the retina and changes can be quantified by optical coherence tomography. While the VEPs and the thickness of the outer plexiform layer appear to reflect the current copper metabolism, the thicknesses of the RNFL, ganglion cell/inner plexiform layer, inner nuclear layer and the total paramacular thickness may be the best indicators of chronic neuronal degeneration.     

Retropupillary Fixation of Iris-Claw Intraocular Lens for Aphakic Eyes in Children

Purpose

To report outcome, complications and safety of retropupillary fixated iris-claw intraocular lenses in a pediatric population.

Design

Retrospective study.

Patients and Methods

Ten consecutive pediatric patients (15 eyes) underwent placement of retropupillary fixated iris-claw intraocular lenses between October 2007 and July 2013 at the Department of Ophthalmology, Medical University Graz and General Hospital Klagenfurt, Austria. Postoperative visual acuity and complications were analyzed.

Results

Median final best-corrected visual acuity improved by 0.12 logMAR from preoperative baseline. Mean postoperative spherical equivalent was -0.05 ± 1.76 D. No serious complications were observed intra- or postoperatively during the entire follow-up period of up to 40 months. One patient experienced a haptic disenclavation with IOL subluxation immediately after a car accident.

Conclusion

Our study demonstrates that iris-claw intraocular lens implantation behind the iris is safe in children with lack of capsular support and yields excellent visual outcome with low complication rate.     

Retroperitoneal Laparoscopic Management of Paraganglioma: A Single Institute Experience

Objectives

To explore the feasibility and safety of retroperitoneal laparoscopic resection of paraganglioma (RLPG) in a large study population.

Methods

In a six-year period, 49 patients with primary retroperitoneal paragangliomas (PG) underwent retroperitoneal laparoscopic surgery in a single center. Medical records were reviewed, and collected the following data, which were clinical characteristics, perioperative data (operative time, estimated blood loss, intraoperative hemodynamic changes, intraoperative and postoperative complications, and open conversions), and follow-up data (recurrence or distant metastases).

Results

All PGs were removed with negative tumor margin confirmed by postoperative histopathology. The operative time of RLPG was 101.59±31.12 minutes, and the estimated blood loss was 169.78±176.70ml. Intraoperative hypertensive and hypotensive episodes occurred in 25 cases and 27 cases, respectively. Two open conversions occurred. Two intraoperative complications occurred but were successfully managed endoscopically. Postoperative complications were minor and unremarkable. No local recurrence or distant metastasis were observed during the follow-up period.

Conclusions

Our experience indicates the feasibility and safety of resection of PGs in a relatively large study population.     

Transient but Significant Visual Field Defects after Robot-Assisted Laparoscopic Radical Prostatectomy in Deep Trendelenburg Position

Background

Robot-assisted laparoscopic radical prostatectomy (RALP) is a minimally invasive surgical procedure for prostate cancer. During RALP, the patient must be in a steep Trendelenburg (head-down) position, which leads to a significant increase in intraocular pressure (IOP). The association of RALP with visual field sensitivity, however, has not been prospectively studied. The purpose of this study was to evaluate prospectively the visual field, retinal nerve fiber layer (RNFL) thickness, and optic disc morphology in 50 normal eyes of 25 male patients that underwent RALP.

Methods

The subjects were 25 males among 33 consecutive patients who underwent uneventful RALP under general anesthesia in our hospital. Visual field tests using the Humphrey visual field analyzer 30-2 SITA-standard program were performed before, 7 days after, and 1-3 months after RALP. IOP was measured before, during, and after RALP; and ophthalmologic examinations, including slit-lamp, fundus examination, and optical coherence tomography (OCT), were scheduled before and 7 days after surgery.

Results

IOP was significantly increased during RALP up to 29.4 mmHg (P<0.01). Postoperative local visual field defects were detected in 7 eyes of 7 subjects dominantly in the lower hemifield without abnormal findings in the optic nerve head or retina, and the visual field recovered to normal within 3 months after surgery. General factors associated with RALP, IOP, RNFL thickness, or optic disc parameters did not differ significantly between eyes with and without postoperative visual field defects, and parameters of OCT measurements were not altered after surgery.

Conclusion

Transient but significant unilateral visual field defects were found in 28% of the subjects examined. The probable cause are the increased IOP and altered perfusion during surgery and ophthalmologic examinations are therefore suggested before and after RALP.     

Comparison of Combined and Sequential Surgery for Proliferative Diabetic Retinopathy: A Single Surgeon Study

Purpose

To compare the results of combined and consecutive surgeries to treat proliferative diabetic retinopathy and cataract.

Methods

Retrospective comparative study. Forty-one patients with proliferative diabetic retinopathy (PDR) were enrolled. Twenty-nine eyes for the combined surgery group and twelve eyes for the sequential group were included. All surgeries were performed by one surgeon. Phacoemulsification was performed using a clear cornea incision. The vitrectomy was performed using a 20-gauge vitreous cutter.

Results

The best corrected visual acuity (BCVA) and intra- and post-operative complications were the main outcome measures. In the combined surgery group, the BCVA increased in 18 (62.1%) eyes, while eight (27.6%) eyes remained stable and three (10.3%) eyes decreased. Postoperative complications included fibrinous exudation in nine eyes, macular edema in three eyes and vitreous hemorrhage in three eyes. In the sequential surgery group, the BCVA increased in seven (58.3%) eyes, remained the same in four (33.3%) eyes and was reduced in one (8.3%) eye. Postoperative complications included macular edema in two eyes, neovascular glaucoma in two eyes and vitreous hemorrhage in one eye.

Conclusions

Both combined and sequential surgeries are safe and effective for treating PDR and cataracts. The combined surgery had a higher incidence of fibrinous exudation.     

No-Reflow Phenomenon in Central Retinal Artery Occlusion: Incidence,Risk Factors,and Clinical Implications

Purpose

To investigate the incidence and risk factors of the no-reflow phenomenon in central retinal artery occlusion (CRAO) patients and to determine its effects on visual and anatomic outcomes.

Methods

In 102 eyes with CRAO in which arterial recanalization was obtained within 1 week from baseline, fluorescein angiography images obtained at baseline and 1 week were retrospectively reviewed. The no-reflow phenomenon in the retina was defined as macular capillary nonperfusion following arterial recanalization on fluorescein angiographs. We investigated the incidence and risk factors for the no-reflow phenomenon and compared the anatomical and visual outcomes between eyes with and without the phenomenon.

Results

Among the 102 CRAO eyes with arterial recanalization, 39 exhibited the no-reflow phenomenon, resulting in an incidence of 38.2%. The incidence among the eyes with treatment-induced and spontaneous recanalization was 43.4% and 15.8%, respectively, and it increased with the CRAO stage. CRAO stage and increased central macular thickness were risk factors for the phenomenon, with an odds ratio of 4.47 [95% confidence interval (CI), 1.19–16.8; P = 0.027] and 1.69 (95% CI, 1.12–2.55; P = 0.012) per 100-μm increase, respectively. The visual outcome was significantly poorer and retinal atrophy and photoreceptor disruption was greater in eyes with the no-reflow phenomenon than in those without.

Conclusions

The no-reflow phenomenon may occur after arterial recanalization in approximately one-third of CRAO patients and can affect anatomical and visual outcomes. This phenomenon may provide an additional explanation regarding the permanent retinal damage and vision loss in eyes with CRAO.     

Microcystic Inner Nuclear Layer Changes and Retinal Nerve Fiber Layer Defects in Eyes with Glaucoma

Objective

To examine microcystic inner nuclear layer (INL) changes in glaucomatous eyes and to determine associated factors.

Design

Retrospective, cross-sectional, observational study.

Methods

Two hundred seventeen eyes of 133 patients with primary open angle glaucoma (POAG), 41 eyes of 32 patients with preperimetric glaucoma and 181 normal eyes of 117 subjects were ultimately included. Microcystic INL lesions were examined with infrared fundus images and with 19 vertical spectral domain optical coherence tomography (SD-OCT) images in the macular area.

Results

Microcystic INL changes were observed in 6.0% of eyes with POAG, but none of the normal eyes or eyes with preperimetric glaucoma showed microcystic INL changes. The proportion of eyes with advanced glaucoma was significantly larger (P = 0.013) in eyes with microcystic lesions than without. The visual field mean deviation (MD) slope was also significantly worse (P = 0.027) in eyes with microcystic lesions. No significant differences were observed in age, sex, refraction, axial length, intraocular pressure, or MD value between eyes with and without microcystic INL lesions. In several cases, microcystic INL lesions occurred along with glaucomatous visual field progression. The retinal nerve fiber layer (RNFL) thickness (P = 0.013) and ganglion cell layer (GCL) + inner plexiform layer thickness (P = 0.023) were significantly lower in areas with microcystic lesions than without. The INL was also significantly thicker (P = 0.002) in areas with microcystic lesions.

Conclusions

Microcystic INL lesions in glaucomatous eyes are closely associated with RNFL and GCL thinning and correlated with worse MD slope. These INL lesions may indicate focal and progressive damage in glaucoma.     

Specific EEG Sleep Pattern in the Prefrontal Cortex in Primary Insomnia

Objective

To assess the specific prefrontal activity in comparison to those in the other main cortical areas in primary insomnia patients and in good sleepers.

Methods

Fourteen primary insomnia patients and 11 good sleepers were included in the analysis. Participants completed one night of polysomnography in the sleep lab. Power spectra were calculated during the NREM (Non-rapid eyes movements) and the REM (Rapid eyes movements) sleep periods at prefrontal, occipital, temporal and central electrode positions.

Results

During the NREM sleep, the power spectra did not differ between groups in the prefrontal cortex; while primary insomnia patients exhibited a higher beta power spectrum and a lower delta power spectrum compared to good sleepers in other areas. During the REM sleep, the beta1 power spectrum was lower in the prefrontal cortex in primary insomnia patients compared to good sleepers; while no significant difference between groups was obtained for the other areas.

Conclusions

The present study shows a specific prefrontal sleep pattern during the whole sleep period. In addition, we suggest that primary insomnia patients displayed a dysfunction in the reactivation of the limbic system during the REM sleep and we give additional arguments in favor of a sleep-protection mechanism displayed by primary insomnia patients.     

Morphology and Function over a One-Year Follow Up Period after Intravitreal Dexamethasone Implant (Ozurdex) in Patients with Diabetic Macular Edema

Background

To investigate changes in macular morphology and function after an intravitreal dexamethasone implant for diabetic macular edema (DME).

Methods

Twenty-seven eyes in 27 treatment-naive patients affected by DME were treated with intravitreal Ozurdex® injections (IVOI) and followed up 12 months to evaluate morphological and functional changes by means of best-corrected visual acuity (BCVA), microperimetry (MP1), multifocal electroretinography (mfERG), pattern electroretinography (PERG) and spectral domain optical coherence tomography (SD-OCT).

Results

Both BCVA and retinal sensitivity improved significantly at one month after the IVOI (p = 0.031 and p<0.0001, respectively). After five months, the improvement of BCVA remained statistically significant compared with baseline values (p = 0.022); retinal sensitivity improvement was statistically significant for up to four months after the IVOI (p = 0.059). Moreover, central macular thickness significantly decreased for up to four months. Interestingly, PERG and mfERG values did not change significantly for up to four months post-IVOI, but then began to worsen.

Conclusions

In eyes with DME, intravitreal dexamethasone implant determined morphological and functional improvement as soon as one month and for up to four months after the treatment.     

Immediate versus Delayed Sequential Bilateral Cataract Surgery: A Systematic Review and Meta-Analysis

Background

Immediately sequential bilateral cataract surgery (ISBCS), the cataract surgery that is performed in both eyes simultaneously, is gaining popularity worldwide compared to the traditional treatment paradigm: delayed sequential bilateral cataract surgery (DSBCS), the surgery that is performed in each eye on a different day as a completely separate operation. ISBCS provides advantages to patients and patients’ families in the form of fewer hospital visits. Additionally, patients enjoy rapid rehabilitation, lack of anisometropia - potentially reducing accidents and falls, and avoid suboptimal visual function in daily life. The hospital may benefit due to lower cost.

Objective

To perform a systematic review and meta-analysis to evaluate ISBCS and DSBCS.

Data Sources

Databases including MEDLINE, EMBASE, BIOSIS, CINAHL, Health Economic Evaluations Database (HEED), ISI Web of Science (Thomson-Reuters) and the Cochrane Library were searched.

Participants

Not applicable.

Methods

Literature was systematically reviewed using EPPI-Reviewer 4 gateway. Meta-analysis was conducted using STATA v. 13.0. Standardized mean difference (SMD) and 95% confidence intervals (CI) were calculated and heterogeneity was assessed using I² statistics. Fixed-effect and random-effect models were computed based on heterogeneity. Meta-analysis was done by instrument used to calculate utility score.

Results

In total, 9,133 records were retrieved from multiple databases and an additional 128 records were identified through grey literature search. Eleven articles with 3,657 subjects were included for analysis. Our meta-analysis results indicated significant improvement in post-operative utility score using TTO, EQ5D, HUI3, VF-7, and VF-14 and a non-significant improvement using Catquest questionnaire for both surgeries. For ISBCS versus DSBCS, utility-specific fixed-effect model provided an overall SMD of the utility score using the TTO method as 0.12 (95% CI: -0.15, 0.40), EQ5D as 0.14 (95% CI: -0.14, 0.41), HUI3 as 0.12 (95% CI: -0.15, 0.40), VF-7 as -0.02 (95% CI: -0.15, 0.10), and Catquest Questionnaire as 1.45 (95% CI: -0.88, 2.01). The results for utility score, which were measured using various instruments, indicated non-significant improvement in the utility due to DSBCS compared to ISBCS. However, a significant improvement in post-operative utility score was seen using Catquest questionnaire for ISBCS compared to DSBCS. The included studies using VF-14 instrument were highly heterogeneous (I² = 97.1%). Results provided SMD of -0.25 (95% CI:-1.06, 0.57) using VF-14 indicating non-significant improvement in the utility due to DSBCS compared to ISBCS surgery. Best corrected visual acuity (BCVA) significantly improved after both surgeries (overall SMD of BCVA due to ISBCS was -1.79 (95% CI: -2.45, -1.14) and due to DSBCS was -1.53 (95% CI: -2.25, -0.81)). A non-significant improvement was seen in BCVA due to ISBCS when compared to DSBCS (SMD = -0.18; 95% CI: -0.37, 0.01).

Conclusion

Both surgeries, ISBCS and DSBCS significantly improve patients’ quality of life and visual acuity. Further, ISBCS may deliver certain additional benefits at the individual and societal levels as well.     

Aging Dogs Manifest Myopia as Measured by Autorefractor

Objective

Dogs, like humans, experience eye changes with aging: hardening and clouding of the lens and accumulated oxidative damage from UV sunlight. It has been debated whether such changes could be affecting the visual function of dogs. The objective of this study was to determine if autorefractometry could be used to measure visual function in dogs.

Animals and Methods

Nine Beagle dogs (ages 1 to 14 years) were examined by a veterinary ophthalmologist and their eyes determined to be free of cataracts. Spherical equivalent refractive error was measured by handheld autorefractor (Welch Allyn SureSight) under both indirect and direct lighting conditions with five measurements per condition, per eye. Measures were repeated on three different days for each dog within six weeks. Nonparametric statistics were used to detect differences among lighting conditions and test days, and between eyes. Spearmen correlation assessed the visual measurement outcomes’ association with age.

Results

There was no difference for day-to-day or between-eye measurements. Significantly, the Beagles showed a myopic shift with aging (average spherical equivalent ranged from plano to -3.00 diopters), suggesting that dogs become more near-sighted as they age (r = -0.48 and -0.73 under direct and indirect lights; p<0.05 both). Younger dogs were able to make larger accommodation changes from indirect light to direct light conditions, indicating a more flexible lens (r = -0.50, p<0.05).

Conclusions

Although designed for humans, the hand-held autorefractor technique is applicable to dogs and sensitive to light conditions. The age-associated myopic shift could be expected to compromise dogs’ visual functions.     

Functional Visual Acuity of Early Presbyopia

Purpose

To evaluate visual function in patients with early presbyopia using the functional visual acuity (FVA) test.

Methods

This study included 27 eyes of 27 healthy older volunteers (mean age, 44.1 ± 2.6 years) and 14 eyes of 14 healthy young volunteers (mean age, 28.4±4.8 years). The distance-corrected visual acuity (DCVA), distance-corrected near VA (DCNVA), subjective amplitude of accommodation (AA), and distance and near pupillary diameters were measured. The distance FVA and distance-corrected near FVA (DCNFVA) were measured using the FVA Measurement System. The standard Schirmer test and standard tear break-up time measurement also were performed.

Results

The logarithm of the minimum angle of resolution (logMAR) DCVA was better than 0 in all subjects. The percentages of subjects with logMAR DCNVA below 0 was significantly lower in the presbyopia group than in the young group. The DCNFVA in the presbyopia group was significantly (P < 0.001) poorer than the DCNVA in that group. Significant linear negative correlations were seen between the DCNVA and AA (r = -0.507, P < 0.001) and the DCNFVA and AA (r = -0.681, P < 0.001) in the older subjects. Stepwise regression analysis showed that only the AA was a significant factor predictive of the DCNFVA in the presbyopia group. Tear function parameters were not adopted in the regression model.

Conclusions

Measurement of the DCNFVA can detect decreased AA in early presbyopia better than measurement of the conventional near VA. The DCNFVA is a good index for early presbyopia.     

Intraoperative Electroretinograms before and after Core Vitrectomy

Purpose

To evaluate retinal function by intraoperative electroretinograms (ERGs) before and after core vitrectomy.

Design

Retrospective consecutive case series.

Method

Full-field photopic ERGs were recorded prior to the beginning and just after core vitrectomy using a sterilized contact lens electrode in 20 eyes that underwent non-complicated vitreous surgery. A light-emitted diode was embedded into the contact lens, and a stimulus of 150 ms on and 350 ms off at 2 Hz was delivered. The amplitudes and latencies of the a-, b-, and d-waves, photopic negative response (PhNR), and oscillatory potentials (OPs) were analyzed. The intraocular temperature at the mid-vitreous was measured at the beginning and just after the surgery with a thermoprobe.

Results

The intraocular temperature was 33.2 ± 1.3°C before and 29.4 ± 1.7°C after the vitrectomy. The amplitudes of the PhNR and OPs were significantly smaller after surgery, and the latencies of all components were prolonged after the surgery. These changes were not significantly correlated with the changes of the temperature.

Conclusion

Retinal function is reduced just after core vitrectomy in conjunction with significant temperature reduction. The differences in the degree of alterations of each ERG component suggests different sensitivity of each type of retinal neuron.     

The Role of Anterior Nuclei of the Thalamus: A Subcortical Gate in Memory Processing: An Intracerebral Recording Study

Objective

To study the involvement of the anterior nuclei of the thalamus (ANT) as compared to the involvement of the hippocampus in the processes of encoding and recognition during visual and verbal memory tasks.

Methods

We studied intracerebral recordings in patients with pharmacoresistent epilepsy who underwent deep brain stimulation (DBS) of the ANT with depth electrodes implanted bilaterally in the ANT and compared the results with epilepsy surgery candidates with depth electrodes implanted bilaterally in the hippocampus. We recorded the event-related potentials (ERPs) elicited by the visual and verbal memory encoding and recognition tasks.

Results

P300-like potentials were recorded in the hippocampus by visual and verbal memory encoding and recognition tasks and in the ANT by the visual encoding and visual and verbal recognition tasks. No significant ERPs were recorded during the verbal encoding task in the ANT. In the visual and verbal recognition tasks, the P300-like potentials in the ANT preceded the P300-like potentials in the hippocampus.

Conclusions

The ANT is a structure in the memory pathway that processes memory information before the hippocampus. We suggest that the ANT has a specific role in memory processes, especially memory recognition, and that memory disturbance should be considered in patients with ANT-DBS and in patients with ANT lesions.ANT is well positioned to serve as a subcortical gate for memory processing in cortical structures.     

Defects of the Lamina Cribrosa in High Myopia and Glaucoma

Purpose

We evaluated the prevalence and characteristics of the defects of the lamina cribrosa (LC) in high myopia and glaucoma, and compared them with control eyes using swept-source optical coherence tomography (SS-OCT).

Methods

One hundred fifty-nine eyes of 108 participants were divided into four subgroups; high myopia with glaucoma (MG, 67 eyes of 46 subjects), glaucoma without high myopia (G, 22 eyes of 13 subjects), high myopia without glaucoma (M, 35 eyes of 29 subjects), and a control group with neither glaucoma nor high myopia (C, 35 eyes of 20 subjects). The LC defects were identified and located using a standardized protocol in serial horizontal OCT scans. The prevalence rates of the defects were compared among the groups. Demographic and ocular factors were compared between eyes with and without defects.

Results

LC defects were observed in one eye (0.03%) in the C group, 8 eyes (22.9%) in the M group, 11 eyes (50%) in the G group, and 28 eyes (41.8%) in the MG group. The prevalence rates of the defects differed significantly among the groups (P = 0.0009). Most eyes with defects in the G and MG groups (79.5%) had damage in the corresponding visual hemifields. Other factors such as visual acuity, intraocular pressure, axial length, refractive error, disc ovality, or parapapillary atrophy area did not differ significantly between eyes with and without LC defects.

Conclusions

High myopia and glaucoma significantly increased the risk of LC damage. The LC damage in non-glaucomatous highly myopic eyes may at least partly explain the increased risk of developing glaucoma in myopic eyes.