Potentially compromised systemic and local lactate metabolic balance in glaucoma, which could increase retinal glucose and glutamate concentrations.

To investigate the association between lactate metabolism and glaucoma, we conducted a multi-institutional cross-sectional clinical study and a retinal metabolomic analysis of mice with elevated intraocular pressure (IOP) induced by intracameral microbead injection. We compared lactate concentrations in serum and aqueous humor in age-matched 64 patients each with primary open-angle glaucoma (POAG) and cataract. Neither serum nor aqueous humor lactate concentrations differed between the two groups. Multiple regression analysis revealed that only body mass index showed a significant positive correlation with serum and aqueous humor lactate concentration in POAG patients (rs = 0.376, P = 0.002, and rs = 0.333, P = 0.007, respectively), but not in cataract patients. L-Lactic acid was one of the most abundantly detected metabolites in mouse retinas with gas chromatography and mass spectrometry, but there were no significant differences among control, 2-week, and 4-week IOP elevation groups. After 4 weeks of elevated IOP, D-glucose and L-glutamic acid ranked as the top two for a change in raised concentration, roughly sevenfold and threefold, respectively (ANOVA, P = 0.004; Tukey-Kramer, P < 0.05). Glaucoma may disrupt the systemic and intraocular lactate metabolic homeostasis, with a compensatory rise in glucose and glutamate in the retina.

Aqp9 Gene Deletion Enhances Retinal Ganglion Cell (RGC) Death and Dysfunction Induced by Optic Nerve Crush: Evidence that Aquaporin 9 Acts as an Astrocyte-to-Neuron Lactate Shuttle in Concert with Monocarboxylate Transporters To Support RGC Function and Survival.

Aquaporin 9 (AQP9) is an aquaglyceroporin that can transport lactate. Accumulating evidence suggests that astrocyte-to-neuron lactate shuttle (ANLS) plays a critical role in energy metabolism in neurons, including retinal ganglion cells (RGCs). To test the hypothesis that AQP9, in concert with monocarboxylate transporters (MCTs), participates in ANLS to maintain function and survival of RGCs, Aqp9-null mice and wild-type (WT) littermates were subjected to optic nerve crush (ONC) with or without intravitreal injection of an MCT2 inhibitor. RGC density was similar between the Aqp9-null mice and WT mice without ONC, while ONC resulted in significantly more RGC density reduction in the Aqp9-null mice than in the WT mice at day 7. Positive scotopic threshold response (pSTR) amplitude values were similar between the two groups without ONC, but were significantly more reduced in the Aqp9-null mice than in the WT mice 7days after ONC. MCT2 inhibitor injection accelerated RGC death and pSTR amplitude reduction only in the WT mice with ONC. Immunolabeling revealed that both RGCs and astrocytes expressed AQP9, that ONC predominantly reduced astrocytic AQP9 expression, and that MCTs 1, 2, and 4 were co-localized with AQP9 at the ganglion cell layer. These retinal MCTs were also co-immunoprecipitated with AQP9 in the WT mice. ONC decreased the co-immunoprecipitation of MCTs 1 and 4, but did not impact co-immunoprecipitation of MCT2. Retinal glucose transporter 1 expression was increased in Aqp9-null mice. Aqp9 gene deletion reduced and increased the intraretinal L-lactate and D-glucose concentrations, respectively. Results suggest that AQP9 acts as the ANLS to maintain function and survival of RGCs.

Dimethyl Fumarate Promotes the Survival of Retinal Ganglion Cells after Optic Nerve Injury, Possibly through the Nrf2/HO-1 Pathway.

This study aimed to verify whether dimethyl fumarate (DMF) promotes the survival of retinal ganglion cells (RGCs) after optic nerve crush (ONC) accompanied by activation of the NF-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. We examined changes in the densities of tubulin ß3 (TUBB3)-positive RGCs and the amplitudes of the positive scotopic threshold response (pSTR), reflecting the functional activity of RGCs, recorded on an electroretinogram, with daily administration of DMF, on day 7 after ONC. Furthermore, immunohistochemical and immunoblotting analyses were performed to study the activation of the Nrf2/HO-1 pathway using retinas treated with daily administration of DMF. Daily administration of DMF increasedthe density of TUBB3-positive RGCs in a dose-dependent fashion and significantly increased the amplitude of the pSTR. Immunohistochemical analysis showed that DMF administration increased the immunoreactivity for Nrf2 and HO-1, a potent antioxidant enzyme, in RGCs immunolabeled with RNA-binding protein with multiple splicing (RBPMS). Immunoblotting analysis revealed an increase in the nuclear expression of Nrf2 and marked upregulation of HO-1 after DMF administration. These results suggest that DMF has survival-promoting effects in RGC after ONC, possibly via the Nrf2/HO-1 pathway.

Relationship between Vision-Related Quality of Life and Central 10° of the Binocular Integrated Visual Field in Advanced Glaucoma.

To investigate the relationships between sensitivity loss in various subfields of the central 10° of the binocular integrated visual field (IVF) and vision-related quality of life (VRQoL) in 172 patients with advanced glaucoma. Using the Random Forest algorithm, which controls for inter-correlations among various subfields of the IVF, we analysed the relationships among the Rasch analysis-derived person ability index (RADPAI), age, best-corrected visual acuity (BCVA), mean total deviations (mTDs) of eight quadrant subfields in the IVF measured with the Humphrey Field Analyzer (HFA) 10-2 program (10-2 IVF), and mTDs of the upper/lower hemifields in the IVF measured with the HFA 24-2 program (24-2 IVF). Significant contributors to RADPAIs were as follows: the inner and outer lower-right quadrants of the 10-2 IVF contributed to the dining and total tasks; the lower-left quadrant of the 10-2 IVF contributed to the walking, going out and total tasks; the lower hemifield of the 24-2 IVF contributed to the walking, going out, dining, miscellaneous and total tasks; and BCVA contributed more to the letter, sentence, dressing and miscellaneous tasks than to others. The impact of damage in different 10-2 IVF subfields differed significantly across daily tasks in patients with advanced glaucoma.

Efficacy and safety of brinzolamide/timolol fixed combination compared with timolol in Japanese patients with open-angle glaucoma or ocular hypertension.

PURPOSE: To evaluate the efficacy and safety of brinzolamide 1%/timolol 0.5% fixed-combination (BRINZ/TIM-FC) therapy compared with timolol 0.5% (TIM) monotherapy in Japanese patients with open-angle glaucoma or ocular hypertension. METHODS: This randomized, double-masked, multicenter study included Japanese patients aged ≥20 years. Patients were treated during a 4-week observation period with TIM monotherapy in advance of randomization to treatment with topical BRINZ/TIM-FC or TIM monotherapy twice daily for 8 weeks. The primary endpoint was mean reduction in intraocular pressure (IOP) from baseline to week 8 at 2 hours postinstillation. Adverse events (AEs) were recorded at each visit. RESULTS: A total of 301 patients (BRINZ/TIM-FC, n=150; TIM, n=151; age [mean ± standard deviation], 61±13 years) were enrolled. Mean IOP reductions from baseline were greater with BRINZ/TIM-FC than with TIM at weeks 4 and 8 at 0 and 2 hours postinstillation (all P≤0.0001), with mean reductions of -3.2 mmHg with BRINZ/TIM-FC and -1.4 mmHg with TIM at week 8, 2 hours postinstillation. Although AEs were observed in 19% of all patients (BRINZ/TIM-FC, 20%; TIM, 19%), all AEs were mild or moderate. CONCLUSION: BRINZ/TIM-FC therapy was associated with significantly greater reductions in IOP compared with TIM, and it was well tolerated in Japanese patients with open-angle glaucoma or ocular hypertension.

Intraocular pressure lowering effect of once daily versus once weekly latanoprost instillation in the same normal individuals.

This study tested whether once weekly instillation of latanoprost exerts the similar IOP lowering effect as once daily instillation in the same individuals. Latanoprost was administered on right eyes of eight healthy male volunteers once daily first for 24 days, which was followed by the 31-day washout and the subsequent once weekly instillation for another 24 days. The mean baseline IOP was 12.06 +/- 1.50 (range, 10.0 to 14.0) mmHg, whereas the mean IOP during once daily treatment was 9.87 +/- 1.71 mmHg, which was significantly lower than the former (p=0.025). The mean washout IOP was 12.56 +/- 2.16 mmHg, which was similar to the baseline IOP. The mean IOP during once weekly instillation of latanoprost was 11.34 +/- 1.51 mmHg, which was not statistically different from the washout IOP. Four of the 8 subjects showed 15% or more reduction in IOP both during once daily and once weekly instillations, two of whom were overlapped. Since the magnitude of the IOP reduction with once daily use was higher than that with once weekly use even in the responders, the current protocol of once daily instillation should be respected.

Postreceptoral contributions to the light-adapted ERG of mice lacking b-waves.

The purpose of this study was to determine the contributions of postreceptoral neurons to the light-adapted ERG of the Nob mouse, a model for complete-type congenital stationary night blindness (CSNB1) that lacks a b-wave from depolarizing bipolar cells. Ganzfeld ERGs were recorded from anesthetized adult control mice, control mice injected intravitreally with L-2-amino-4-phosphonobutyric acid (Control APB mice) to remove On pathway activity, and Nob mice. ERGs also were recorded after PDA (cis-2,3-piperidine-dicarboxylic acid, 3-5mM) was injected to block transmission to hyperpolarizing (Off) bipolar and horizontal cells, and all third-order neurons. Stimuli were brief (<4ms, 0.4-2.5log sc td s) and long (200ms, 2.5-4.6log sc td) LED flashes (lambda(max)=513nm, on a rod suppressing background (2.6log sc td). Sinusoidal modulation of the LEDs (mean, 2.6log sc td; contrast, 100%; 3-36Hz) was used to study flicker ERGs. Brief-flash ERGs of Nob mice presented as long-lasting negative waves with a positive-going intrusion that started about 50ms after the flash and peaked around 120ms. Control APB mice had similar responses, and in both cases, PDA removed the positive-going intrusion. For long flashes, PDA removed a small, slow "d-wave" after light offset. With sinusoidal stimulation, the fundamental (F1) amplitude of control mice ERG peaked at 8Hz ( approximately 70microV). For Nob mice the peak was approximately 20microV at 6Hz before PDA and approximately 10muV at 3Hz or lower after PDA. F1 responses were present up to 21Hz in control and Nob eyes and 15Hz in Nob eyes after PDA. Between 3 and 6Hz, F1 phase was 170-210 degrees more delayed in Nob than control mice; phase was hardly altered by PDA. With vector analysis, a substantial postreceptoral input to the Nob flicker ERG was revealed. In control mice, the second harmonic (F2) response showed peaks of approximately 10mocrpV at 3Hz and 13Hz. Nob mice showed almost no F2. In summary, in this study it was found that in Nob mice, postreceptoral neurons from the Off pathway make a positive-going contribution to the light-adapted flash ERG, and contribute substantially to sinusoidal flicker ERG.

Near complete loss of retinal ganglion cells in the math5/brn3b double knockout elicits severe reductions of other cell types during retinal development.

Retinal ganglion cells (RGCs) are the first cell type to differentiate during retinal histogenesis. It has been postulated that specified RGCs subsequently influence the number and fate of the remaining progenitors to produce the rest of the retinal cell types. However, several genetic knockout models have argued against this developmental role for RGCs. Although it is known that RGCs secrete cellular factors implicated in cell proliferation, survival, and differentiation, until now, limited publications have shown that reductions in the RGC number cause significant changes in these processes. In this study, we observed that Math5 and Brn3b double null mice exhibited over a 99% reduction in the number of RGCs during development. This severe reduction of RGCs is accompanied by a drastic loss in the number of all other retinal cell types that was never seen before. Unlike Brn3b null or Math5 null animals, mice null for both alleles lack an optic nerve and have severe retinal dysfunction. Results of this study support the hypothesis that RGCs play a pivotal role in the late phase of mammalian retina development.

Test of the paired-flash electroretinographic method in mice lacking b-waves.

Previous studies of rod photoreceptors in vivo have employed a paired-flash electroretinographic (ERG) technique to determine rod response properties. To test whether absence versus presence of the ERG b-wave affects the photoreceptor response derived by the paired-flash method, we examined paired-flash-derived responses obtained from nob mice, a mutant strain with a defect in signal transduction between photoreceptors and ON bipolar cells that causes a lack of the b-wave. Normal littermates of the nob mice served as controls. The normalized amplitude-intensity relation of the derived response determined in nob mice at the near-peak time of 86 ms was similar to that determined for the controls. The full time course of the derived rod response was obtained for test flash strengths ranging from 0.11 to 17.38 scotopic cd s m(-2) (sc cd s m(-2)). Time-course data obtained from nob and control mice exhibited significant but generally modest differences. With saturating test flash strengths, half-recovery times for the derived response of nob versus control mice differed by approximately 60 ms or less about the combined (nob and control) average respective values. Time course data also were obtained before versus after intravitreal injection of L-2-amino-4-phosphonobutyrate (APB) (which blocks transmission from photoreceptors to depolarizing bipolar cells) and of cis 2,3-piperidine dicarboxylic acid (PDA) (which blocks transmission to OFF bipolar cells, and to horizontal, amacrine and ganglion cells). Neither APB nor PDA substantially affected derived responses obtained from nob or control mice. The results provide quantitative information on the effect of b-wave removal on the paired-flash-derived response in mouse. They argue against a substantial skewing effect of the b-wave on the paired-flash-derived response obtained in normal mice and are consistent with the notion that, to good approximation, this derived response represents the isolated flash response of the photoreceptors in both nob and normal mice.

Comparison of Pentacam Scheimpflug camera with ultrasound pachymetry and noncontact specular microscopy in measuring central corneal thickness.

PURPOSE: Although central corneal thickness (CCT) can be measured by several methods, interchangeability of different modalities has not been fully investigated. CCT is known to correlate with intraocular pressure (IOP). The aim of this study was to evaluate the agreement of Pentacam Scheimpflug system with noncontact specular microscopy (NCSM) and ultrasound (US) pachymetry in measuring CCT and the relation between IOP taken with Goldmann applanation tonometer (GAT) and the CCT measured with these three methods. METHODS: The right eyes of 135 enrolled persons without antiglaucoma drug use (100 females and 35 males), who comprised 32 patients with primary open-angle glaucoma, 14 with ocular hypertension, 45 with primary angle-closure glaucoma, and 44 controls, were studied. Intermethod comparison of CCT was made by the 95% limits of agreement analysis according to Bland and Altman. Linear regression analysis was used to assess the relationship between IOP and CCT taken with each modality. RESULTS: The mean CCT (+/-SD) taken with Scheimpflug, US, and NCSM was 559.49 +/- 38.44 microm, 553.01 +/- 39.33 microm, and 552.04 +/- 42.95 microm, respectively. The average values of CCT taken with the three instruments were not significantly different (one-factor ANOVA; p = 0.26), although the marginal mean difference between Scheimpflug and US or NCSM was statistically significant (paired t test; p = 0.0009 and 0.005, respectively). The 95% limits of agreement were 6.47 +/- 43.21 microm between Scheimpflug and US, 7.45 +/- 58.86 microm between Scheimpflug and NCSM, and 0.98 +/- 51.69 microm between US and NCSM. There was a positive association between IOP and CCT measured with US or NCSM, whereas there was no correlation between IOP and CCT measured with Scheimpflug. CONCLUSIONS: Although CCT values measured with Scheimpflug, US, and NCSM are closely similar, clinicians should keep in mind that these methods are not simply interchangeable.

Quantification of retinal nerve fiber layer thickness reduction associated with a relative afferent pupillary defect in asymmetric glaucoma.

AIM: The relative afferent pupillary defect (RAPD) is an important clinical sign of asymmetrical retinal ganglion cell and axonal damage. Although glaucoma essentially affects bilateral eyes, a subset of patients manifests asymmetrical glaucomatous optic neuropathy (GON), which exhibits an RPAD in the more advanced eyes. However, the degree to which axonal loss occurs before an RAPD is clinically detectable has not been substantiated. The purpose of this study is to assess the relationship between the depth of a clinically detectable RAPD and the reduction ratio of retinal nerve fiber layer (RNFL) thickness in the more advanced eyes relative to that in the contralateral less advanced eyes of patients with asymmetrical GON. METHODS: Enrolled were 29 consecutive glaucoma patients with the clinically detectable RAPD. An RAPD was quantified by placing log-scaled neutral density filters over the less advanced eyes while performing the swinging flashlight test. Average RNFL thickness was determined using the Fast RNFL thickness programme of optical coherence tomography 3000. Correlation coefficient and Linear regression analyses were used in assessing the relationship between the RAPD and the ratio of RNFL thickness in the more advanced eyes relative to that in the less advanced. RESULTS: RAPD ranged from 0.6 to 2.4 log units. The log-scaled RAPD had a statistically significantly inversed correlation with the average RNFL thickness ratio (r(s) = -0.729, p<0.0001). Linear regression analysis found an equation that the average RNFL thickness ratio in the more affected eyes relative to that in the less advanced (%) = (0.827-0.169xRAPD (log units))x100 (R(2) = 0.557, p<0.0001). CONCLUSIONS: When an RAPD is clinically detected, the RNFL thickness in the more advanced eyes was in average reduced to about 73% of that in the less advanced.

Agreement of rebound tonometer in measuring intraocular pressure with three types of applanation tonometers.

PURPOSE: To evaluate the agreement of iCare rebound tonometer in measuring intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), Tonopen XL, and noncontact tonometer, and the influence of the central corneal thickness (CCT) on IOP measurements made with these four tonometers in 45 (12 control and 33 glaucomatous or ocular hypertensive) eyes. DESIGN: Clinically relevant experimental study. METHODS: Tonometer intermethod agreement was assessed by the Bland-Altman method. The relations of CCT with absolute IOP values and intertonometer differences were analyzed by linear regression. RESULTS: The mean differences (95% limits of agreement) in IOP readings between iCare and GAT, Tonopen XL, and noncontact tonometer were 1.40 +/- 4.29, 0.00 +/- 4.78, and 2.22 +/- 4.19 mm Hg, respectively. All tonometries had a marked association with CCT. As the CCT got thicker, iCare considerably overestimated GAT and Tonopen XL. CONCLUSIONS: Although influenced by CCT, iCare agrees well with applanation tonometers.

[Correlations among GDx-variable corneal compension, optical coherence tomography, and Heidelberg retina tomograph and relationships between these structural parameters and visual field indices].

PURPOSE: In glaucoma patients, to compare the correlations among parameters measured by Heidelberg Retina Tomography(HRT) and retinal nerve fiber layer thickness (RNFLT) measured by GDx-variable corneal compensation (GDx-VCC) and optical coherence tomography (OCT), and to assess the relationship among these structural parameters, and visual field damage. METHODS: A unilateral eye of 110 patients with open-angle glaucoma were included in this study. Each individual was analyzed by HRT (version 3.04), GDx-VCC (version 5.3.2), and OCT-1 (version A6 X1). The correlations among these parameters regarding global area, superior sector, and inferior sector were obtained from the 3 instruments and compared. The correlations among the mean deviation (MD) in the Humphrey field analysis and the parameters in global area from the 3 instruments were calculated. RESULTS: The MD showed quadratic regressions to each global parameter (GDx-VCC; 0.625 (nerve fiber indicator): OCT 0.616 (average RNFLT); HRT, 0.501 (rim area)). Most parameters in OCT and GDx-VCC had highly significant correlations. The rim area showed the highest correlation in each sector to RNFLT with GDx-VCC or OCT among HRT parameters. CONCLUSIONS: These structural parameters derived from GDx-VCC, OCT and HRT analyses had bilinear correlation to the MD. Retinal nerve fiber loss detected on GDx-VCC and OCT correlated linearly with the neuroretinal rim area measured by HRT. These instruments may be useful in monitoring structural changes in glaucoma.

Comparison of confocal scanning laser ophthalmoscopy, scanning laser polarimetry and optical coherence tomography to discriminate ocular hypertension and glaucoma at an early stage.

BACKGROUND: The aim was to compare the ability of confocal scanning laser ophthalmoscopy (CSLO), scanning laser polarimetry (SLP), and optical coherence tomography (OCT) to discriminate eyes with ocular hypertension (OHT), glaucoma-suspect eyes (GS) or early glaucomatous eyes (EG) from normal eyes. METHODS: Ocular hypertension, GS, and EG were defined as normal disc with intraocular pressure >21 mmHg, glaucomatous disc without visual field loss, and glaucomatous disc accompanying the early glaucomatous visual filed loss respectively. Ninety-three normal eyes, 26 OHT, 55 GS, and 67 EG were enrolled. Optic disc configuration was analyzed by CSLO (version 3.04), whereas retinal nerve fiber layer thickness was analyzed by SLP (GDx-VCC; version 5.3.2) and OCT-1 (version A6X1) in each individual. The measurements were compared in the four groups of patients. Receiver operating characteristic curve (ROC) and area under the curve (AUC) discriminating OHT, GS or EG from normal eyes were compared for the three instruments. RESULTS: Most parameters in GS and EG eyes showed significant differences compared with normal eyes. However, there were few significant differences between normal and OHT eyes. No significant differences were observed in AUCs between SLP and OCT. In EG eyes, the greatest AUC parameter in OCT (inferior--120; 0.932) had a higher AUC than that in CSLO (vertical cup/disc ratio; 0.845; P=0.017). In GS, the greatest AUC parameter in OCT (average retinal nerve fiber layer [RNFL] thickness; 0.869; P=0.002) and SLP (nerve fiber indicator [NFI]; 0.875; P=0.002) had higher AUC than that in CSLO (vertical cup/disc ratio; 0.720). CONCLUSIONS: Three instruments were useful in identifying GS and EG eyes. For glaucomatous eyes with or without early visual field defects, SLP and OCT performed similarly or had better discriminating abilities compared with CSLO.

Intrinsically photosensitive retinal ganglion cells detect light with a vitamin A-based photopigment, melanopsin.

In mammals, intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate non-image-forming visual functions such as pupillary light reflex (PLR) and circadian photoentrainment. This photosensitivity requires melanopsin, an invertebrate opsin-like protein expressed by the ipRGCs. The precise role of melanopsin remains uncertain. One suggestion has been that melanopsin may be a photoisomerase, serving to regenerate an unidentified pigment in ipRGCs. This possibility was echoed by a recent report that melanopsin is expressed also in the mouse retinal pigment epithelium (RPE), a key center for regeneration of rod and cone pigments. To address this question, we studied mice lacking RPE65, a protein essential for the regeneration of rod and cone pigments. Rpe65-/- ipRGCs were approximately 20- to 40-fold less photosensitive than normal at both single-cell and behavioral (PLR) levels but were rescued by exogenous 9-cis-retinal (an 11-cis-retinal analog), indicating the requirement of a vitamin A-based chromophore for ipRGC photosensitivity. In contrast, 9-cis-retinal was unable to restore intrinsic photosensitivity to melanopsin-ablated ipRGCs, arguing against melanopsin functioning merely in photopigment regeneration. Interestingly, exogenous all-trans-retinal was also able to rescue the low sensitivity of rpe65-/- ipRGCs, suggesting that melanopsin could be a bistable pigment. Finally, we detected no melanopsin in the RPE and no changes in rod and cone sensitivities due to melanopsin ablation. Together, these results strongly suggest that melanopsin is the photopigment in the ipRGCs.

Ganglion cells are required for normal progenitor- cell proliferation but not cell-fate determination or patterning in the developing mouse retina.

The vertebrate retina develops from an amorphous sheet of dividing retinal progenitor cells (RPCs) through a sequential process that culminates in an exquisitely patterned neural tissue. A current model for retinal development posits that sequential cell-type differentiation is the result of changes in the intrinsic competence state of multipotent RPCs as they advance in time and that the intrinsic changes are influenced by continuous changes in the extracellular environment. Although several studies support the proposition that newly differentiated cells alter the extrinsic state of the developing retina, it is still far from clear what role they play in modifying the extracellular environment and in influencing the properties of RPCs. Here, we specifically ablate retinal ganglion cells (RGCs) as they differentiate, and we determine the impact of RGC absence on retinal development. We find that RGCs are not essential for changing the competence of RPCs, but they are necessary for maintaining sufficient numbers of RPCs by regulating cell proliferation via growth factors. Intrinsic rather than extrinsic factors are likely to play the critical roles in determining retinal cell fate.

Regulation of retinal cone bipolar cell differentiation and photopic vision by the CVC homeobox gene Vsx1.

Cone bipolar cells of the vertebrate retina connect photoreceptors with ganglion cells to mediate photopic vision. Despite this important role, the mechanisms that regulate cone bipolar cell differentiation are poorly understood. VSX1 is a CVC domain homeoprotein specifically expressed in cone bipolar cells. To determine the function of VSX1, we generated Vsx1 mutant mice and found that Vsx1 mutant retinal cells form but do not differentiate a mature cone bipolar cell phenotype. Electrophysiological studies demonstrated that Vsx1 mutant mice have defects in their cone visual pathway, whereas the rod visual pathway was unaffected. Thus, Vsx1 is required for cone bipolar cell differentiation and regulates photopic vision perception.

Goniosynechialysis with lens aspiration and posterior chamber intraocular lens implantation for glaucoma in spherophakia.

A 17-year-old girl presented with bilateral angle-closure glaucoma associated with spherophakia. A previous bilateral laser iridotomy failed to control intraocular pressure (IOP). Goniosynechialysis with lens aspiration and posterior chamber intraocular lens implantation were performed in both eyes. Peripheral iridoplasty was performed 3 days later. The postoperative IOP was controlled without medication for 12 months in the right eye and 24 months in the left eye. By restructuring the physiologic aqueous outflow route, goniosynechialysis safely and effectively treated secondary glaucoma from spherophakia.

Diabetes has an additive effect on neural apoptosis in rat retina with chronically elevated intraocular pressure.

PURPOSE: Diabetes mellitus (DM) is a risk factor for open-angle glaucoma, although the mechanistic interrelationship of the two is debatable. The purpose of this study is to test whether DM augments neural apoptosis in rat retina with chronically elevated intraocular pressure (IOP). METHODS: Sprague-Dawley rats were made diabetic by intraperitoneal injection of streptozotocin (STZ). At one month after STZ injection, three episcleral veins in one eye were cauterized to elevate IOP. Rats without STZ injection were treated likewise as diabetic controls. At 2 weeks, 1 month, and 2 months after cauterization, the retina was dissected, flat-mounted, and subjected to terminal dUTP nick end labeling (TUNEL) staining. TUNEL positive cells per unit area of the whole retina were measured. RESULTS: DM did not affect base line IOP or augment IOP elevation due to episcleral vein cauterization. TUNEL positive cells, which primarily consisted of the neurons and glial cells in the inner retina including retinal ganglion cell (RGC), were counted consistently eight times more in the diabetic retina without IOP elevation than diabetic controls (n = 9, p < 0.001). The cauterization significantly elevated IOP up to 28.9 mmHg (p < 0.001), which was reduced over time, and substantially induced apoptosis in a IOP-dependent fashion (p < 0.001). Ocular hypertensive retinas with DM had significantly more TUNEL positive cells than those without DM despite of the similar time course of IOP changes (p < 0.001). CONCLUSIONS: DM has an additive effect on apoptosis induction by chronic elevation of IOP. Diabetes may act as a risk factor of open-angle glaucoma by increasing susceptibility of retinal cells including retinal ganglion cells to apoptosis triggered by additional stresses such as elevated IOP.

Evaluation of the effect of aging on retinal nerve fiber layer thickness measured by optical coherence tomography.

PURPOSE: To evaluate the relationship between age and retinal nerve fiber layer (RNFL) thickness in normal subjects, as measured by optical coherence tomography (OCT). METHODS: One hundred and forty-four normal subjects (144 eyes), ranging from 16 to 84 years of age, were enrolled in this cross-sectional study. The RNFL thickness was determined using OCT with three circle scans 3.4 mm in diameter. RESULTS: The average RNFL thickness was inversely correlated with age (r = -0.348, p < 0.001). Analyzing the quadrants as a parameter, RNFL thickness in the superior, temporal and inferior quadrants also decreased with age. Using 30-degree segments, there were significant correlations between age and the RNFL thickness of temporal segments (7-11 o'clock). The average RNFL thickness had the highest correlation among all parameters (r = -0.348, p < 0.001). Regarding nasal quadrant thickness, RNFL ratios (average, superior, temporal and inferior RNFL thickness relative to the nasal quadrant thickness) were not significantly correlated with age. The refractive error did not affect RNFL thickness (r = 0.091, p = 0.276). CONCLUSION: Our study revealed that RNFL thickness, in particular in the temporal quadrant, measured by OCT significantly decreased with age. Age has to be taken into consideration when we compare RNFL thickness between normal and glaucomatous eyes.