Glaucoma Surgery Shifts Among Medicare Beneficiaries After 2022 Reimbursement Changes in the United States.

PRCIS: This study revealed the best-estimated surgical procedural counts for 2021 and 2022 and suggests a direct influence of coding and reimbursement changes on surgical device selection. PURPOSE: To analyze utilization rates of glaucoma surgeries and minimally invasive (microinvasive) glaucoma surgery among US Medicare beneficiaries between 2021 and 2022. DESIGN: Retrospective comparative analysis of 68,118 unique patients. METHODS: National claims data from a 5% sample of all Medicare beneficiaries were utilized to compare glaucoma procedure counts between the first quarter of 2021 and the first quarter of 2022. Duplicate claims were excluded, and 50 modifiers were counted as 2 distinct procedures. A multiplier was applied to estimate annual utilization for the entire Medicare population. χ 2 analysis was employed to compare categorical data from the 2 time periods. RESULTS: Current Procedural Terminology codes for angle-based stenting decreased by an estimated 20,960 procedures between 2021 and 2022 (28.60%). Goniotomy increased by an estimated 11,680 procedures (66.97%) and canaloplasty increased by an estimated 6640 procedures (47.43%). Glaucoma surgeries decreased by an estimated 5760 procedures (4.25%) despite an increase of cataract surgery by 234,960 procedures (15.63%), an increase in YAG capsulotomy by 19,280 procedures (3.31%), and an increase in intravitreal injections by 146,320 procedures (3.86%). CONCLUSION: Despite overall surgical volume increases among the ophthalmology procedures, angle-based stenting utilization decreased significantly with an accompanying trend change following the coding and reimbursement changes implemented in January 2022. Of the minimally invasive (microinvasive) glaucoma surgery procedures, goniotomy and canaloplasty counts increased the most between these periods. Trabeculectomy and glaucoma drainage device procedures continued to decrease, following well-established trends. Future studies are warranted to examine how these shifts in utilization may impact patient care outcomes.

Impact of Fellowship Training on Practice Patterns of Glaucoma Surgeons Treating Medicare fee-for-service Beneficiaries.

PURPOSE: Analyze practice patterns of glaucoma surgeons with and without fellowship training. MATERIALS AND METHODS: Physician-specific 2017 Medicare data were obtained from the Centers for Medicare & Medicaid Services website. Current Procedural Terminology codes identified procedures including iStent, tube shunts, trabeculectomy, complicated trabeculectomy, endoscopic cyclophotocoagulation, internal Xen Implant, external Xen or Express shunt, Gonioscopy-Assisted Transluminal Trabeculotomy, and Kahook Dual Blade Goniotomy. Physicians with fellowship training were identified via the American Glaucoma Society website. RESULTS: A total of 1547 glaucoma surgeons were identified, of which 319 had completed fellowship training. Overall, fellowship-trained glaucoma surgeons performed more services (50.4 ± 47.0 vs 40.5 ± 35.3, P < .001) with a larger variety of procedures (1.8 ± 1.0 vs 1.3 ± 0.6, P < .001) than those without fellowship training. Surgeons without fellowship training were more likely to perform iStent and endoscopic cyclophotocoagulation and less likely to perform the remaining procedures than their fellowship-trained counterparts. Medicare payments did not differ between groups and the number of Medicare beneficiaries only differed for internal Xen implant (P = .03). Patient comorbidity burden was similar between groups with about one-third of patients being diagnosed with ischemic heart disease. CONCLUSIONS: Surgeons without fellowship training can treat a similar volume of glaucoma patients as those with fellowship training. However, based on surgical procedures employed, their practices are skewed towards mild and moderate glaucoma and they are more limited in their breadth of procedures. In addition, ischemic heart disease was prevalent in the glaucoma patient population.

The Vision Detroit Project: Integrated Screening and Community Eye-Health Education Interventions Improve Eyecare Awareness.

PURPOSE: Poor eye-health knowledge and health literacy are pervasive, contributing to worse outcomes. This study aims to examine short- and long-term eye-health knowledge retention following eye-health education interventions in adults. METHODS: Vision Detroit was an outreach vision screening program that integrated a 5-Point Teaching Intervention (5PTI), at a Southwest Community Center (SW-CC) from 2015-2017. The 5PTI consists of eye-health learning points developed to verbally educate patients. During vision screenings, eye-health knowledge tests were administered before and after 5PTI (Test 1 and Test 2, respectively). In 2016, Community Eye-Health Education Interventions (CHEI) were initiated at the SW-CC. During CHEI, bilingual healthcare students taught voluntary SW-CC members the 5PTI learning points, regardless of participant interest to attend future screenings. CHEI sessions occurred on separate dates prior to vision screening events. Test 1 and Test 2 scores were compared for all participants. Test 1 scores were compared for those who underwent CHEI prior to vision screening (CHEI positive) versus those who did not (CHEI negative). RESULTS: Two-hundred-seventeen adult patients met inclusion criteria, with 75.8% women, 82.6% Hispanic, mean age 50.4 ± 16.2 years, 74.6% had high school or less education, and 49.2% had health insurance. Test 1 to Test 2 scores improved after 5PTI (71.2 ± 26.4% vs. 97.2 ± 9.9%, p < .00001). Forty-eight participants attended CHEI and subsequent vision screening. Test 1 scores were higher among those CHEI positive versus CHEI negative (81.1 ± 2.1% vs. 68.3 ± 3.4%, p = .0027). CONCLUSION: Simple eye-health education interventions, delivered during vision screenings and via community-based education, can improve eye-health knowledge.

Analysis of ophthalmology subspecialty opioid prescribing patterns during the opioid public health crisis.

OBJECTIVE: To describe opioid prescribing practices of ophthalmology subspecialties and determine whether opioid prescribing has decreased during the public health crisis. DESIGN: Retrospective cohort study. PARTICIPANTS: Ophthalmologists prescribing at least 11 medications billed to the Medicare Part D prescription drug plan. METHODS: Publicly available Medicare data sets based on claims from the years 2016, 2017, and 2018 were used. Fellowship status was assumed based on subspecialty society membership or use of specified Current Procedural Terminology codes. The main outcome was the percentage of physicians in each subspecialty prescribing opioids. RESULTS: The database included 19,762, 19,790, and 19,840 ophthalmologists in the years 2016, 2017, and 2018, respectively. Only the subspecialties of comprehensive ophthalmology (43.5% vs 39.6% vs 35.7%; p < 0.001; φc = 0.066), retina (66.5% vs 60.7% vs 54.5%; p < 0.001; φc = 0.101), cornea (82.8% vs 83.9% vs 77.2%; p = 0.03; φc = 0.076), and glaucoma (53.4% vs 46.4% vs 42.0%; p < 0.001; φc = 0.094) underwent a small but significant reduction in the proportion of physicians prescribing opioids. The subspecialties of oculoplastics (86%-88.8%), cornea (77.2%-82.8%), retina (54.5%-66.5%), and pediatrics (51.5%-57.9%) had the highest percentage of physicians prescribing opioids. The subspecialties of glaucoma, uveitis, and comprehensive ophthalmology had the lowest percentage of opioid prescribers. Among physicians with more than 10 opioid claims, median opioid claims did not change drastically. Opioids contributed only a small proportion of medication claims for all subspecialties. CONCLUSION: All subspecialties experienced either a small reduction or no significant change in the percentage of opioid prescribers during the period analyzed. We hope to encourage collaboration between ophthalmology subspecialties in striving to reduce opioid prescribing. Further studies are needed to better fine-tune opioid prescribing practices.

Consensual Ophthalmotonic Reaction Following Selective Laser Trabeculoplasty.

Aim: "Consensual ophthalmotonic reaction" refers to changes in intraocular pressure (IOP) in one eye, which is accompanied by a corresponding change in IOP in the contralateral eye. This study evaluates whether monocular administration of selective laser trabeculoplasty (SLT) leads to a consensual ophthalmotonic reaction and how long this effect lasts. Materials and methods: A retrospective chart review was performed on patients receiving SLT at Kresge Eye Institute in Detroit, MI, from January 2015 to August 2016. Patients were excluded if they had previous history of glaucoma incisional and/or laser procedures; required additional laser trabeculoplasty; had glaucoma medication changes during the follow-up period; experienced no decrease in IOP during the follow-up period; or had a diagnosis of angle closure on gonioscopy. Various demographic, clinical, and surgical data were collected. IOP measurements were collected at baseline and postoperatively at 1-3 months, 4-9 months, and 12-15 months. Results: At all follow-up periods, the IOP of the treated eye was decreased from baseline IOP (p ≤ 0.05, paired t-test). For the fellow eye, there was a statistically significantly decrease from baseline up to the 4-9 months follow-up period (p ≤ 0.05, paired t-test). Linear regression analysis of the percent reduction in IOP from baseline in the SLT-treated eye with the fellow eye shows a mild correlation at all-time points: R2 = 0.284 (p < 0.001) at 1-3 months; R2 = 0.348 (p < 0.001) at 4-9 months; R2 = 0.118 (p = 0.054) at 12-15 months. Conclusion: This study showed that monocular administration of SLT results in a consensual ophthalmotonic reaction. The consensual ophthalmotonic reaction appears to last for up to 4-9 months. Clinical significance: Therefore, although SLT does lead to a consensual ophthalmotonic reaction, monocular administration of SLT is not a reliable method of long-term IOP control for the contralateral non-SLT-treated eye. How to cite this article: Nassiri N, Mei F, Tokko H, et al. Consensual Ophthalmotonic Reaction Following Selective Laser Trabeculoplasty. J Curr Glaucoma Pract 2022;16(1):36-40.

Factors Associated with 5-year Glaucomatous Progression in Glaucoma Suspect Eyes: A Retrospective Longitudinal Study.

Purpose: Using demographic, clinical, visual field, and optical coherence tomography (OCT) variables to study the association of 5-year glaucomatous progression in glaucoma suspect eyes. Patients and methods: This is a retrospective longitudinal clinical study. Inclusion criteria consisted of glaucoma suspect eyes (i.e., concerning cup-to-disk ratio and/or intraocular pressure (IOP) >21 mm Hg), age ≥ 30 years old, follow-up time of 5 years, best-corrected visual acuity (BCVA) of 20/100 or better, spherical equivalent (SE) higher than 8 diopters and an astigmatism less than 3 diopters. Eyes with glaucoma-determined by two consecutive, reliable visual field tests-were excluded, as well as any eyes with any clinically significant retinal or neurological disease. The percentage of glaucoma suspect eyes, which progressed to glaucoma within a 5-year period, was calculated. Study subjects were divided into the following groups: eyes that progressed to glaucoma and those that did not. Results: In the 288 patients which we looked at, 365 total eyes, 323 eyes had concerning cup-to-disk ratio and 42 had ocular hypertension. Bivariate analysis showed that the eyes which progressed to glaucoma had significantly worse mean deviation, increased pattern standard deviation (PSD), and less visual field index (VFI). Our bivariate analysis also showed a thinner average, superior and inferior retinal nerve fiber layer thickness (RNFL), and more severe average, superior, and inferior RNFL damages (i.e., color grading scale) at baseline. Logistic regression analysis showed that only PSD and severe inferior RNFL damage (i.e., red color) to be significantly associated with 5-year glaucomatous progression. Conclusion: Segmental RNFL damage and pattern standard deviation are associated with 5-year glaucomatous progression in glaucoma suspect eyes. How to cite this article: Nassiri N, Das S, Patel V, et al. Factors Associated with 5-year Glaucomatous Progression in Glaucoma Suspect Eyes: A Retrospective Longitudinal Study. J Curr Glaucoma Pract 2022;16(1):11-16.

Three-year outcomes of trabeculectomy and Ahmed valve implant in patients with prior failed filtering surgeries.

PURPOSE: To compare three-year surgical outcomes of trabeculectomy versus Ahmed valves in patients with prior failed trabeculectomy. METHODS: This is a longitudinal retrospective comparative study of one-hundred twenty adult patients with prior failed trabeculectomy who underwent a repeat trabeculectomy or Ahmed valve implant. Demographic and clinical data were collected up to 3 years on all study participants at the Kresge Eye Institute from 2004 to 2016. Visual acuity, intraocular pressure, number of intraocular pressure reducing medications, and success rates at various time points up to 3 years after repeat surgery were the main outcome variables. RESULTS: Sixty-five and sixty eyes were included in the trabeculectomy and the Ahmed valve groups, respectively. Baseline intraocular pressure significantly decreased in both groups at 3 years (p < 0.01). The number of medications was relatively similar to baseline in both study groups at 3 years (p > 0.05). There was no statistically significant difference between the two groups in visual acuity, percentage of intraocular pressure reduction, number of medications, or success rates at any follow-up time points (p > 0.05 for all). CONCLUSIONS AND RELEVANCE: After 3 years, both trabeculectomy and Ahmed valves significantly reduced intraocular pressure from baseline, but with relatively similar number of medications compared to baseline. There was no significant difference in any outcome measure between trabeculectomy and Ahmed valves at any follow-up time points. These results may suggest neither trabeculectomy or Ahmed valves are superior in patients with previously failed trabeculectomies.

SLC26A7 constitutes the thiocyanate-selective anion conductance of the basolateral membrane of the retinal pigment epithelium.

Anion channels in the retinal pigment epithelium (RPE) play an essential role in the transport of Cl- between the outer retina and the choroidal blood to regulate the ionic composition and volume of the subretinal fluid that surrounds the photoreceptor outer segments. Recently, we reported that the anion conductance of the mouse RPE basolateral membrane is highly selective for the biologically active anion thiocyanate (SCN-), a property that does not correspond with any of the Cl- channels that have been found to be expressed in the RPE to date. The purpose of this study was to determine the extent to which SLC26A7, a SCN- permeable-anion exchanger/channel that was reported to be expressed in human RPE, contributes to the RPE basolateral anion conductance. We show by quantitative RT-PCR that Slc26a7 is highly expressed in mouse RPE compared with other members of the Slc26 gene family and Cl- channel genes known to be expressed in the RPE. By applying immunofluorescence microscopy to mouse retinal sections and isolated cells, we localized SLC26A7 to the RPE basolateral membrane. Finally, we performed whole cell and excised patch recordings from RPE cells acutely isolated from Slc26a7 knockout mice to show that the SCN- conductance and permeability of its basolateral membrane are dramatically smaller relative to wild-type mouse RPE cells. These findings establish SLC26A7 as the SCN--selective conductance of the RPE basolateral membrane and provide new insight into the physiology of an anion channel that may participate in anion transport and pH regulation by the RPE.

Factors Associated with the Development of Posterior Capsule Opacification Requiring Yttrium Aluminum Garnet Capsulotomy.

SIGNIFICANCE: Determining risk factors for posterior capsule opacification will allow for further interventions to reduce the risk of development and thus additional procedures. PURPOSE: The purpose of this study was to investigate risk factors associated with development of clinically significant posterior capsule opacification requiring yttrium aluminum garnet (YAG) capsulotomy. METHODS: Medical records of patients (≥18 years) who underwent cataract surgery between January 1, 2011, and March 31, 2014, at Kresge Eye Institute were reviewed. Three hundred eyes requiring YAG capsulotomy up to 3 years after cataract surgery were included in the YAG capsulotomy group. Three hundred eyes not requiring YAG capsulotomy up to 3 years after cataract surgery were selected via age-matched simple randomization (control group). RESULTS: The YAG capsulotomy group included patients with younger age (65.8 ± 11.3 vs. 70.1 ± 10.6 years, P < .001), more men (42.67 vs. 34.67%, P = .04), fewer patients with hypertension (73.00 vs. 83.00%, P < .001), and more patients with hydrophilic intraocular lenses (74.67 vs. 47.00%, P < .001). Logistic regression analysis demonstrated a negative association between YAG capsulotomy and age (coefficient, -0.04; 95% confidence interval [CI], 0.95 to 0.98; P < .001) and hydrophobic intraocular lenses (coefficient, -1.50; 95% CI, 0.15 to 0.33; P < .001), and a positive association with presence of glaucoma (coefficient, 0.88; 95% CI, 1.39 to 4.17; P = .002). Elapsed time to YAG capsulotomy was sooner in patients with a history of uveitis (95% CI, 5.10 to 9.70 months; P = .02) and insertion of hydrophilic intraocular lenses (95% CI, 18.67 to 21.57 months; P < .001). CONCLUSIONS: Results of this study suggest that development of visually significant posterior capsule opacification is associated with younger age, glaucoma, and hydrophilic intraocular lenses, and it occurs earlier among those with hydrophilic intraocular lenses and a history of uveitis.

Electrophysiological impact of thiocyanate on isolated mouse retinal pigment epithelial cells.

Our recent electrophysiological analysis of mouse retinal pigment epithelial (RPE) cells revealed that in the presence of 10 mM external thiocyanate (SCN-), voltage steps generated large transient currents whose time-dependent decay most likely results from the accumulation or depletion of SCN- intracellularly. In the present study, we investigated the effects of more physiologically relevant concentrations of this biologically active anion. In whole cell recordings of C57BL/6J mouse RPE cells, we found that, over the range of 50 to 500 µM SCN-, the amplitude of transient currents evoked by voltage steps was proportional to the extracellular SCN- concentration. Transient currents were also produced in RPE cells when the membrane potential was held constant and the external SCN- concentration was rapidly increased by pressure-ejecting 500 µM SCN- from a second pipette. Other results indicate that the time dependence of currents produced by both approaches results from a change in driving force due to intracellular SCN- accumulation or depletion. Finally, by applying fluorescence imaging and voltage-clamping techniques to BALB/c mouse RPE cells loaded with the anion-sensitive dye MQAE, we demonstrated that in the presence of 200 or 500 µM extracellular SCN-, depolarizing voltage steps increased the cytoplasmic SCN- concentration to an elevated steady state within several seconds. Collectively, these results indicate that, in the presence of physiological concentrations of SCN- outside the RPE, the conductance and permeability of the RPE cell membranes for SCN- are sufficiently large that SCN- rapidly approaches electrochemical equilibrium within the cytoplasm when the membrane voltage or external SCN- concentration is perturbed.

RETINAL AND CHOROIDAL VASCULAR OCCLUSION FOLLOWING AQUEOUS MISDIRECTION SYNDROME IN A PATIENT WITH SICKLE CELL TRAIT.

PURPOSE: To report a patient with retinal and choroidal vascular occlusion as a presenting sign of sickle cell trait following the development of aqueous misdirection syndrome. METHODS: Retrospective chart review. RESULTS: A patient treated for bilateral chronic angle-closure glaucoma with sequential EX-PRESS glaucoma filtration device surgery developed sequential bilateral aqueous misdirection syndrome. The left eye developed retinal arterial and localized choroidal vascular occlusions subsequent to an acute elevation in intraocular pressure and possibly the use of oral acetazolamide. The patient was subsequently found to have sickle cell trait. The right eye developed aqueous misdirection with acute elevation of intraocular pressure as well, but the patient was not treated with oral acetazolamide and did not develop vascular occlusion. CONCLUSION: Retinal and choroidal vascular occlusions can be the presenting sign of a patient with sickle cell trait. Sickle cell screening may be beneficial in African American or Middle Eastern patients after an acute rise in intraocular pressure, particularly before initiation of treatment with oral carbonic anhydrase inhibitors.

A platform for assessing outer segment fate in primary human fetal RPE cultures.

The daily shedding and renewal of photoreceptor outer segments (OS) is critical for maintaining vision. This process relies on the efficient uptake, degradation, and sorting of shed OS material by the retinal pigment epithelium (RPE). Poor OS degradation has been linked to retinal degenerations such as Stargardt disease and may contribute to macular degeneration. While primary human fetal RPE cultures have emerged as a valuable model of in vivo human RPE function, surprisingly few studies have utilized the model for tracking the degradation and fate of OS components in the RPE. Here, we establish an improved platform for studying this topic by modifying existing protocols and creating new methods. Our human fetal culture model facilitates studies of RPE secretion in response to OS ingestion, preserves RPE differentiation and polarization during live-cell imaging of OS phagocytosis, and minimizes costs. We optimize Mer tyrosine kinase-dependent OS phagocytosis assays specifically in human fetal cultures and provide a simple and accurate method for measuring total OS consumption by the RPE. Finally, we utilize chemical transfection, dextran labeling, and immunocytochemistry to evaluate key players in OS degradation, including lysosomes and autophagy proteins. To facilitate quantification of autophagy vesicles, we develop customized image analysis macros in the Fiji/ImageJ software environment. These protocols will facilitate a broad range of studies in human fetal RPE cultures aimed at determining the ultimate fate of OS components after ingestion, a critical step in understanding the pathogenesis of numerous retinal diseases.

Factors Associated with Conjunctival Erosions after Ahmed Glaucoma Valve Implantation.

PURPOSE: To investigate the frequency of conjunctival erosions in a series of patients who underwent Ahmed valve implantation in a tertiary referral center and to study risk factors associated with the conjunctival erosions. METHODS: This is a single-center, retrospective case-control study of all patients who underwent Ahmed valve implantation between October 2006 and July 2016 at the Kresge Eye Institute in Detroit, Michigan. The series consisted of 306 eyes (277 patients) that underwent Ahmed valve implantation. The rate of conjunctival erosions was determined. Univariate, bivariate, and Cox-proportional hazard analyses were performed to identify factors associated with conjunctival erosions. RESULTS: During the study period, 23 erosions occurred in 306 eyes (7.52%). Aphakia was significantly more common in eyes with erosions (P < 0.05). Aphakia (P = 0.02), uveitic glaucoma (P = 0.03), and longer post-operative use of topical steroids (P < 0.04) significantly increased the risk of erosions based on the Cox model. There were similar rates of erosions with each type of patch graft. No conjunctival erosion was observed after using the modified scleral tunnel method (n = 10). CONCLUSIONS: The overall erosion rate was 7.52% in our series. Uveitic glaucoma, aphakia, and longer post-operative use of topical steroids were significantly associated with conjunctival erosions.

Mouse retinal pigment epithelial cells exhibit a thiocyanate-selective conductance.

The basolateral membrane anion conductance of the retinal pigment epithelium (RPE) is a key component of the transepithelial Cl- transport pathway. Although multiple Cl- channels have been found to be expressed in the RPE, the components of the resting Cl- conductance have not been identified. In this study, we used the patch-clamp method to characterize the ion selectivity of the anion conductance in isolated mouse RPE cells and in excised patches of RPE basolateral and apical membranes. Relative permeabilities ( PA/ PCl) calculated from reversal potentials measured in intact cells under bi-ionic conditions were as follows: SCN- >> ClO4- > [Formula: see text] > I- > Br- > Cl- >> gluconate. Relative conductances ( GA/ GCl) followed a similar trend of SCN- >> ClO4- > [Formula: see text] > I- > Br- ≈Cl- >> gluconate. Whole cell currents were highly time-dependent in 10 mM external SCN-, reflecting collapse of the electrochemical potential gradient due to SCN- accumulation or depletion intracellularly. When the membrane potential was held at -120 mV to minimize SCN- accumulation in cells exposed to 10 mM SCN-, the instantaneous current reversed at -90 mV, revealing that PSCN/ PCl is approximately 500. Macroscopic current recordings from outside-out patches demonstrated that both the basolateral and apical membranes exhibit SCN- conductances, with the basolateral membrane having a larger SCN- current density and higher relative permeability for SCN-. Our results suggest that the RPE basolateral and apical membranes contain previously unappreciated anion channels or electrogenic transporters that may mediate the transmembrane fluxes of SCN- and Cl-.

Characterization of the R162W Kir7.1 mutation associated with snowflake vitreoretinopathy.

KCNJ13 encodes Kir7.1, an inwardly rectifying K(+) channel that is expressed in multiple ion-transporting epithelia. A mutation in KCNJ13 resulting in an arginine-to-tryptophan change at residue 162 (R162W) of Kir7.1 was associated with snowflake vitreoretinal degeneration, an inherited autosomal-dominant disease characterized by vitreous degeneration and mild retinal degeneration. We used the Xenopus laevis oocyte expression system to assess the functional properties of the R162W (mutant) Kir7.1 channel and determine how wild-type (WT) Kir7.1 is affected by the presence of the mutant subunit. Recordings obtained via the two-electrode voltage-clamp technique revealed that injection of oocytes with mutant Kir7.1 cRNA resulted in currents and cation selectivity that were indistinguishable from those in water-injected oocytes, suggesting that the mutant protein does not form functional channels in the plasma membrane. Coinjection of oocytes with equal amounts of mutant and WT Kir7.1 cRNAs resulted in inward K(+) and Rb(+) currents with amplitudes that were ∼17% of those in oocytes injected with WT Kir7.1 cRNA alone, demonstrating a dominant-negative effect of the mutant subunit. Similar to oocytes injected with WT Kir7.1 cRNA alone, coinjected oocytes exhibited inwardly rectifying Rb(+) currents that were more than seven times larger than K(+) currents, indicating that mutant subunits did not alter Kir7.1 channel selectivity. Immunostaining of Xenopus oocytes or Madin-Darby canine kidney cells expressing mutant or WT Kir7.1 demonstrated distribution of both proteins primarily in the plasma membrane. Our data suggest that the R162W mutation suppresses Kir7.1 channel activity, possibly by negatively impacting gating by membrane phosphadidylinositol 4,5-bisphosphate.

KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium.

Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this ß-subunit may contribute to M-type K(+) channels in this membrane.

Combined posterior chamber intraocular lens, vitrectomy, Retisert, and pars plana tube in noninfectious uveitis.

OBJECTIVE: To assess the safety and efficacy of combined cataract extraction, posterior chamber intraocular lens placement, pars plana vitrectomy, fluocinolone acetonide intravitreal implant (Retisert), and Ahmed valves with pars plana tube (CPR-PT) in eyes with chronic, posterior, noninfectious uveitis. METHODS: Retrospective study of patients who underwent CPR-PT. Outcome measures included visual acuity, intraocular pressure, inflammation, and complications. RESULTS: Eight eyes were included, with a mean follow-up of 18 months. Mean visual acuity improved from 1.89 to 0.14 logMAR (Snellen, counting fingers at 2 ft [0.6 m]) to 20/30; P=.01). Mean intraocular pressure remained stable at 16 to 17 mm Hg (P=.35). The number of glaucoma medications per eye decreased from 2.9 to 0.25 (P=.01). Systemic prednisone therapy was discontinued in all patients by 9 months postoperatively. Inflammation was well controlled in all eyes. CONCLUSION: The CPR-PT procedure allows rapid visual rehabilitation without major short-term complications.

Effects of KCNQ channel modulators on the M-type potassium current in primate retinal pigment epithelium.

Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in monkey retinal pigment epithelium (RPE) and showed that the M-type current in RPE cells is blocked by the specific KCNQ channel blocker XE991. Using patch-clamp electrophysiology, we investigated the pharmacological sensitivity of the M-type current in isolated monkey RPE cells to elucidate the subunit composition of the channel. Most RPE cells exhibited an M-type current with a voltage for half-maximal activation of approximately -35 mV. The M-type current activation followed a double-exponential time course and was essentially complete within 1 s. The M-type current was inhibited by micromolar concentrations of the nonselective KCNQ channel blockers linopirdine and XE991 but was relatively insensitive to block by 10 µM chromanol 293B or 135 mM tetraethylammonium (TEA), two KCNQ1 channel blockers. The M-type current was activated by 1) 10 µM retigabine, an opener of all KCNQ channels except KCNQ1, 2) 10 µM zinc pyrithione, which augments all KCNQ channels except KCNQ3, and 3) 50 µM N-ethylmaleimide, which activates KCNQ2, KCNQ4, and KCNQ5, but not KCNQ1 or KCNQ3, channels. Application of cAMP, which activates KCNQ1 and KCNQ4 channels, had no significant effect on the M-type current. Finally, diclofenac, which activates KCNQ2/3 and KCNQ4 channels but inhibits KCNQ5 channels, inhibited the M-type current in the majority of RPE cells but activated it in others. The results indicate that the M-type current in monkey RPE is likely mediated by channels encoded by KCNQ4 and KCNQ5 subunits.

KCNQ5/K(v)7.5 potassium channel expression and subcellular localization in primate retinal pigment epithelium and neural retina.

Previous studies identified in retinal pigment epithelial (RPE) cells an M-type K(+) current, which in many other cell types is mediated by channels encoded by KCNQ genes. The aim of this study was to assess the expression of KCNQ genes in the monkey RPE and neural retina. Application of the specific KCNQ channel blocker XE991 eliminated the M-type current in freshly isolated monkey RPE cells, indicating that KCNQ subunits contribute to the underlying channels. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE and all five KCNQ transcripts in the neural retina. At the protein level, KCNQ5 was detected in the RPE, whereas both KCNQ4 and KCNQ5 were found in neural retina. In situ hybridization in frozen monkey retinal sections revealed KCNQ5 gene expression in the ganglion cell layer and the inner and outer nuclear layers of the neural retina, but results in the RPE were inconclusive due to the presence of melanin. Immunohistochemistry revealed KCNQ5 in the inner and outer plexiform layers, in cone and rod photoreceptor inner segments, and near the basal membrane of the RPE. The data suggest that KCNQ5 channels contribute to the RPE basal membrane K(+) conductance and, thus, likely play an important role in active K(+) absorption. The distribution of KCNQ5 in neural retina suggests that these channels may function in the shaping of the photoresponses of cone and rod photoreceptors and the processing of visual information by retinal neurons.

Activation of P2X receptors induces apoptosis in human retinal pigment epithelium.

PURPOSE: The retinal pigment epithelium (RPE) is considered a primary site of pathology in age-related macular degeneration (AMD), which is the most prevalent form of irreversible blindness worldwide in the elderly population. Extracellular adenosine triphosphate (ATP) acts as a key signaling molecule in numerous cellular processes, including cell death. The purpose of this study was to determine whether extracellular ATP induces apoptosis in cultured human RPE. METHODS: RPE apoptosis was evaluated by caspase-3 activation, Hoechst staining, and DNA fragmentation. Intracellular Ca(2+) levels were determined by both a cell-based fluorometric Ca(2+) assay and a ratiometric Ca(2+) imaging technique. P2X(7) mRNA and protein expression were detected by reverse transcription-polymerase chain reaction (RT-PCR) and confocal microscopy, respectively. RESULTS: The authors found that both the endogenous P2X(7) agonist ATP and the synthetic, selective P2X(7) agonist 2',3'-O-(4-benzoylbenzoyl)-ATP (BzATP) induced RPE apoptosis, which was significantly inhibited by P2X(7) antagonist oxidized ATP (oATP) but not by the P2 receptor antagonist suramin; both ATP and BzATP increase intracellular Ca(2+) via extracellular Ca(2+) influx; both ATP- and BzATP-induced Ca(2+) responses were significantly inhibited by oATP but not by suramin; ATP-induced apoptosis was significantly inhibited or blocked by BAPTA-AM or by low or no extracellular Ca(2+); and P2X(7) receptor mRNA and protein were expressed in RPE cells. CONCLUSIONS: These findings suggest that P2X receptors, especially P2X(7) receptors, contribute to ATP- and BzATP-induced Ca(2+) signaling and apoptosis in the RPE. Abnormal Ca(2+) homeostasis through the activation of P2X receptors could cause the dysfunction and apoptosis of RPE that underlie AMD.