Thrombospondin 1 polymorphism associated with decreased expression and increased risk of pterygium.

PURPOSE: To assess the potential association of a thrombospondin 1 gene (THBS1) single-nucleotide polymorphism (rs1478604) with thrombospondin 1 (TSP-1) mRNA expression, as well as the risk of pterygium, in a pilot study. METHODS: DNA and RNA were isolated from peripheral blood samples collected from normal volunteer subjects (n = 39). In addition, DNA was isolated from conjunctival tissue samples collected during pterygium excision surgeries (n = 42). Relative expression of TSP-1 mRNA was measured by quantitative RT-PCR, and rs1478604 genotype was determined using a TaqMan SNP genotyping assay. Genotype frequencies were compared with mRNA expression and between pterygium samples and normal controls. RESULTS: Expression of TSP-1 mRNA was significantly lower in the peripheral blood of normal subjects who were homozygous for the C allele of rs1478604 (CC) compared to TT and CT genotypes (p = 0.004). When we compared rs1478604 genotypes between normal and pterygium patients, we found that the CC genotype was also associated with an increased risk of pterygium compared to TT (odds ratio (OR) = 5.39, 95% CI [1.26-22.99], p = 0.028), CT (OR = 7.86, 95% CI [1.92-32.17], p = 0.003), and combined CT and TT genotypes (OR = 6.67; 95% CI = [1.75-25.37]; p = 0.003). CONCLUSIONS: We found that the C allele of rs1478604 was associated with both lower TSP-1 expression and higher risk of pterygium, possibly implicating TSP-1 in the pathogenesis of pterygium.

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.

Rate of Unplanned Vitrectomies in Femtosecond Laser-Assisted Cataract Surgery Compared to Conventional Phacoemulsification.

PURPOSE: To assess the rate of unplanned vitrectomies with femtosecond laser-assisted cataract surgery (FLACS) compared to conventional phacoemulsification at a single, high-volume, multi-surgeon ambulatory surgical center. METHODS: Retrospective, comparative study of phacoemulsification cases performed in a community-based ambulatory surgical center. A chart review of 2,480 consecutive FLACS procedures performed by 30 surgeons and 36,865 consecutive conventional phacoemulsification surgeries performed by 47 surgeons was conducted. The rate of unplanned vitrectomies was evaluated. In eyes with unplanned vitrectomy, the rates of posterior capsule tear, anterior capsule tear, and zonular dehiscence were analyzed. The unplanned vitrectomy rates between early and late FLACS cases were compared using thresholds of greater than 10, 20, and 50 cases. RESULTS: There were 230 (0.62%) and 16 (0.65%) unplanned vitrectomies in the conventional phacoemulsification and FLACS groups, respectively (P = .89). Of the cases requiring unplanned vitrectomy, posterior capsule tear, anterior capsule tear, and zonular dehiscence rates (conventional phacoemulsification vs FLACS) were 70.9% versus 56.3%, 8.3% versus 12.5%, and 20.9% versus 31.3%, respectively (P = .35). The difference in unplanned vitrectomy rates between early and late cases did not reach statistical significance in any threshold group. CONCLUSIONS: FLACS had a rate of unplanned vitrectomy comparable to conventional phacoemulsification. There was no statistically significant difference in unplanned vitrectomy rates between early and late FLACS cases suggesting a short learning curve. [J Refract Surg. 2018;34(9):610-614.].

Assessment of surgeon experience with femtosecond laser-assisted cataract surgery.

PURPOSE: To evaluate the collective user experience with an image-guided femtosecond laser (FSL) for cataract surgery in a high-volume, multi-surgeon, ambulatory surgical center. SUBJECTS AND METHODS: A detailed online survey was distributed to all surgeons in a single ambulatory surgical center who had performed cataract surgery using a FSL since its acquisition in December 2012. Information collected included the number of cases performed, typical surgical techniques and parameters, satisfaction with individual features of the laser (rated on a scale from 1=completely unsatisfied to 10=extremely satisfied) and commentary on ease of use and suggested improvements. RESULTS: Seventeen of 30 surgeons (56.7%) completed the survey, representing a case volume of 1,967 eyes. Fourteen surgeons (82.4%) felt they required ≤10 cases with the FSL to operate with the same safety and control as in standard phacoemulsification surgery. Satisfaction was highest for capsulotomies, lens fragmentation, lens softening, arcuate incisions and the graphic user interface (mean scores 9.4, 8.7, 8.7, 7.2 and 8.9, respectively). Preferred capsulotomy diameter was 4.8-5.2 mm (64.7% of respondents). About half (52.9%) of respondents centered the capsulotomy on the pupil and the other 47.1% centered the capsulotomy using optical coherence tomography. Most respondents (81.3%) preferred transepithelial arcuate incisions compared to intrastromal incisions. Satisfaction was lowest with FSL-created, main, clear corneal incisions and paracenteses (mean scores 4.4 and 4.2, respectively). CONCLUSION: Laser-assisted cataract surgery has a short learning curve and a high rate of user satisfaction. Further software and hardware development is warranted to improve user satisfaction with peripheral and clear corneal incisions.

A novel nomogram for the treatment of astigmatism with femtosecond-laser arcuate incisions at the time of cataract surgery.

PURPOSE: The purpose of this study was to determine an arcuate incision (AI) nomogram to treat astigmatism during femtosecond laser-assisted cataract surgery. METHODS: This is a retrospective, cohort study. Femtosecond laser (FSL)-assisted transepithelial AIs were created at a 9.0 mm optical zone, 80% depth, centered on the limbus. We modified the manual Donnenfeld limbal relaxing incision nomogram to 70% for with-the-rule (WTR), 80% for oblique (OBL), and 100% for against-the-rule (ATR) astigmatism. The correction index (CI) equaled AI-induced astigmatism/target-induced astigmatism. Measures included preoperative keratometric corneal cylinder (Pre Kcyl), postoperative Kcyl (Post Kcyl), and postoperative residual refractive astigmatism (Post RRA). RESULTS: Mean Pre Kcyl and 1-2 months Post RRA in 161 eyes of 116 patients were 0.626±0.417 diopters (D) (range 0.5-2 D), and 0.495±0.400 D (range 0-1.5 D), respectively. Mean absolute astigmatic changes (Pre Kcyl-Post Kcyl) without accounting for axis change in the WTR, ATR, and OBL groups were 0.165±0.383 D (P<0.001), 0.374±0.536 D (P<0.001), and 0.253±0.416 D (P=0.02), respectively. Mean absolute astigmatic changes using RRA as the postoperative measurement (Pre Kcyl-Post RRA) without accounting for axis change were 0.440±0.461 D (P<0.001), 0.238±0.571 D (P<0.05), 0.154±0.450 (P=0.111) in WTR, ATR, and OBL groups, respectively. CIs for WTR, ATR, and OBL were 0.53, 1.01, and 0.95, respectively. There were no intraoperative or postoperative complications related to the AIs. CONCLUSION: Transepithelial FSL-AIs using the modified Donnenfeld nomogram show potential for management of mild to moderate corneal astigmatism. An increase in the magnitude or reduction of the optical zone size for the treatment of WTR and ATR astigmatism for this nomogram may further improve refractive accuracy.